Efficient reagents for the synthesis of 5-, 7-, and 5,7-substituted indoles starting from aromatic amines: Scope and limitations

Journal of Organic Chemistry

Volumn 61, Issue 17, 1996, Pages 5804-5812

  Ezquerra, Jesús ^a   Pedregal, Concepción ^a   Lamas, Carlos ^a   Barluenga, José ^b   Pérez, Marta ^b   García Martín, Miguel Angel ^b   González, José M ^b  

^a CSIC   (Spain)

^b UNIVERSITY OF OVIEDO   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

INDOLE DERIVATIVE;

ARTICLE; DRUG SYNTHESIS; REACTION ANALYSIS;

EID: 0029823888     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo952119+     Document Type: Article

References (119)

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16. (g) Diazo coupling reaction of 3-alkenylphenol: Satomura, M. J. Org. Chem. 1993, 58, 3757.
17. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
18. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
19. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
20. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
21. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
22. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
23. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
24. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
25. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
26. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
27. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
28. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
29. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
30. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
31. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
32. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
33. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
34. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
35. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
36. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
37. The functionalization of the indole ring could be considered an alternative, although regioselectivity remains a challenging synthetic problem in this context. Among the procedures recently described, a significant number are based on organometallic reagents. For recent examples, see the following. Substitution at C-2: (a) Labadie, S. S.; Teng, E. J. Org. Chem. 1994, 59, 4250. (b) Palmisano, G.; Santagostino, M. Synlett 1993, 771. (c) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Heterocycles 1993, 36, 941. (d) Kondo, Y.; Takazawa, N.; Yoshida, A.; Sakamoto, T. J. Chem. Soc., Perkin Trans. 1 1995, 1207. (e) Ciattini, G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1994, 35, 2405. (f) Amat, M.; Hadida, S.; Bosch, J. Tetrahedron Lett. 1994, 35, 793 and references therein. (g) Sakamoto, T.; Kondo, Y.; Takazawa, N.; Yamanaka, H. Tetrahedron Lett. 1993, 34, 5955. (h) Yokoyama, Y.; Ikeda, M.; Saito, M.; Yoda, T.; Suzuki, H.; Murakami, Y. Heterocycles 1990, 31, 1505. Substitution at C-4: (i) Iwao, M. Heterocycles 1993, 36, 29. (j) Semmelhack, M. F.; Knochel, P.; Singleton, T. Tetrahedron Lett. 1993, 34, 5051 and references therein. (k) Somei, M.; Ohta, T.; Shinoda, J.; Somada, Y. Heterocycles 1989, 29, 653. Substitution at C-3/C-4: (l) Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929. (m) Tidwell, J.; Peat, A. J.; Buchwald, S. L. J. Org. Chem. 1994, 59, 7164. (n) Hegedus, L. S.; Sestrick, M. R.; Michaelson, E. T.; Harrington, P. J. J. Org. Chem. 1989, 54, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: (o) Griffen, E. J.; Roe, D. G.; Snieckus, V. J. Org. Chem. 1995, 60, 1484. Substitution at C-6: (p) Hirano, S.; Akai, R.; Shinoda, Y.; Nakatsuka, S. Heterocycles 1995, 41, 255. (q) Teranishi, K.; Nakatsuka, S.; Goto, T. Synthesis 1994, 1018. (r) Nakatsuka, S.; Teranishi, K.; Goto, T. Tetrahedron Lett. 1994, 35, 2699. Substitution at C-7: (s) Carrera, G. M.; Sheppard G. S. Synlett 1994, 93. (t) Somei, M.; Yamada, F.; Hamada, H.; Kawasaki, T. Heterocycles 1989, 29, 643. (u) Somei, M.; Saida, Y. Heterocycles 1985, 23, 3113.
38. See, for instance: (a) Tietze, L. F.; Buhr W. Angew. Chem. 1995, 107, 1485; Angew. Chem., Int. Ed. Engl. 1995, 34, 1366. (b) Boger, D. L. Acc. Chem. Res. 1995, 28, 20. (c) Tidwell, J.; Buchwald, S. L. J. Am. Chem. Soc. 1994, 116, 11797. (d) Fukuyama, T.; Chen, X. J. Am. Chem. Soc. 1994, 116, 3125. (e) Tietze, L. F.; Grote, T. J. Org. Chem. 1994, 59, 192.
39. See, for instance: (a) Tietze, L. F.; Buhr W. Angew. Chem. 1995, 107, 1485; Angew. Chem., Int. Ed. Engl. 1995, 34, 1366. (b) Boger, D. L. Acc. Chem. Res. 1995, 28, 20. (c) Tidwell, J.; Buchwald, S. L. J. Am. Chem. Soc. 1994, 116, 11797. (d) Fukuyama, T.; Chen, X. J. Am. Chem. Soc. 1994, 116, 3125. (e) Tietze, L. F.; Grote, T. J. Org. Chem. 1994, 59, 192.
40. See, for instance: (a) Tietze, L. F.; Buhr W. Angew. Chem. 1995, 107, 1485; Angew. Chem., Int. Ed. Engl. 1995, 34, 1366. (b) Boger, D. L. Acc. Chem. Res. 1995, 28, 20. (c) Tidwell, J.; Buchwald, S. L. J. Am. Chem. Soc. 1994, 116, 11797. (d) Fukuyama, T.; Chen, X. J. Am. Chem. Soc. 1994, 116, 3125. (e) Tietze, L. F.; Grote, T. J. Org. Chem. 1994, 59, 192.
41. See, for instance: (a) Tietze, L. F.; Buhr W. Angew. Chem. 1995, 107, 1485; Angew. Chem., Int. Ed. Engl. 1995, 34, 1366. (b) Boger, D. L. Acc. Chem. Res. 1995, 28, 20. (c) Tidwell, J.; Buchwald, S. L. J. Am. Chem. Soc. 1994, 116, 11797. (d) Fukuyama, T.; Chen, X. J. Am. Chem. Soc. 1994, 116, 3125. (e) Tietze, L. F.; Grote, T. J. Org. Chem. 1994, 59, 192.
42. See, for instance: (a) Tietze, L. F.; Buhr W. Angew. Chem. 1995, 107, 1485; Angew. Chem., Int. Ed. Engl. 1995, 34, 1366. (b) Boger, D. L. Acc. Chem. Res. 1995, 28, 20. (c) Tidwell, J.; Buchwald, S. L. J. Am. Chem. Soc. 1994, 116, 11797. (d) Fukuyama, T.; Chen, X. J. Am. Chem. Soc. 1994, 116, 3125. (e) Tietze, L. F.; Grote, T. J. Org. Chem. 1994, 59, 192.
43. See, for instance: (a) Tietze, L. F.; Buhr W. Angew. Chem. 1995, 107, 1485; Angew. Chem., Int. Ed. Engl. 1995, 34, 1366. (b) Boger, D. L. Acc. Chem. Res. 1995, 28, 20. (c) Tidwell, J.; Buchwald, S. L. J. Am. Chem. Soc. 1994, 116, 11797. (d) Fukuyama, T.; Chen, X. J. Am. Chem. Soc. 1994, 116, 3125. (e) Tietze, L. F.; Grote, T. J. Org. Chem. 1994, 59, 192.
44. Bartoli's reaction: (a) Bartoli, G.; Palmieri, G.; Bosco, M.; Dalpozzo, R. Tetrahedron Lett. 1989, 30, 2129. (b) Dobson, D.; Todd, A.; Gilmore, J. Synth. Commun. 1991, 21, 611. (c) Dobson, D.; Gilmore, J.; Long, D. A. Synlett 1992, 79. (d) Mechanistic studies, see: Bosco, M.; Dalpozzo, R.; Bartoli, G.; Palmieri, G.; Petrini, M. J. Chem. Soc., Perkin Trans. 2 1991, 657.
45. Bartoli's reaction: (a) Bartoli, G.; Palmieri, G.; Bosco, M.; Dalpozzo, R. Tetrahedron Lett. 1989, 30, 2129. (b) Dobson, D.; Todd, A.; Gilmore, J. Synth. Commun. 1991, 21, 611. (c) Dobson, D.; Gilmore, J.; Long, D. A. Synlett 1992, 79. (d) Mechanistic studies, see: Bosco, M.; Dalpozzo, R.; Bartoli, G.; Palmieri, G.; Petrini, M. J. Chem. Soc., Perkin Trans. 2 1991, 657.
46. Bartoli's reaction: (a) Bartoli, G.; Palmieri, G.; Bosco, M.; Dalpozzo, R. Tetrahedron Lett. 1989, 30, 2129. (b) Dobson, D.; Todd, A.; Gilmore, J. Synth. Commun. 1991, 21, 611. (c) Dobson, D.; Gilmore, J.; Long, D. A. Synlett 1992, 79. (d) Mechanistic studies, see: Bosco, M.; Dalpozzo, R.; Bartoli, G.; Palmieri, G.; Petrini, M. J. Chem. Soc., Perkin Trans. 2 1991, 657.
47. Bartoli's reaction: (a) Bartoli, G.; Palmieri, G.; Bosco, M.; Dalpozzo, R. Tetrahedron Lett. 1989, 30, 2129. (b) Dobson, D.; Todd, A.; Gilmore, J. Synth. Commun. 1991, 21, 611. (c) Dobson, D.; Gilmore, J.; Long, D. A. Synlett 1992, 79. (d) Mechanistic studies, see: Bosco, M.; Dalpozzo, R.; Bartoli, G.; Palmieri, G.; Petrini, M. J. Chem. Soc., Perkin Trans. 2 1991, 657.
48. For a review on the Leimgruber-Batcho indole synthesis and its implications to prepare 7-substituted indoles, see: Clark, R. D.; Repke, D. B. Heterocycles 1984, 22, 195.
49. Heath-Brown, B.; Philpott, P. G. J. Chem. Soc. 1965, 7185.
50. For review articles, see: (a) Kalinin, V. N. Synthesis 1992, 413. (b) Sakamoto, T.; Kondo, Y.; Yamanaka, H. Heterocycles 1988, 27, 2225. (c) Vollhardt, K. P. C. Lect. Heterocycl. Chem. 1987, 9, 59. (d) Davidson, J. L.; Preston, P. N. In Advances in Heterocyclic Chemistry; Katritzky, A. R., Ed.; Academic: New York, 1982; Vol. 30, pp 319-402.
51. For review articles, see: (a) Kalinin, V. N. Synthesis 1992, 413. (b) Sakamoto, T.; Kondo, Y.; Yamanaka, H. Heterocycles 1988, 27, 2225. (c) Vollhardt, K. P. C. Lect. Heterocycl. Chem. 1987, 9, 59. (d) Davidson, J. L.; Preston, P. N. In Advances in Heterocyclic Chemistry; Katritzky, A. R., Ed.; Academic: New York, 1982; Vol. 30, pp 319-402.
52. For review articles, see: (a) Kalinin, V. N. Synthesis 1992, 413. (b) Sakamoto, T.; Kondo, Y.; Yamanaka, H. Heterocycles 1988, 27, 2225. (c) Vollhardt, K. P. C. Lect. Heterocycl. Chem. 1987, 9, 59. (d) Davidson, J. L.; Preston, P. N. In Advances in Heterocyclic Chemistry; Katritzky, A. R., Ed.; Academic: New York, 1982; Vol. 30, pp 319-402.
53. For review articles, see: (a) Kalinin, V. N. Synthesis 1992, 413. (b) Sakamoto, T.; Kondo, Y.; Yamanaka, H. Heterocycles 1988, 27, 2225. (c) Vollhardt, K. P. C. Lect. Heterocycl. Chem. 1987, 9, 59. (d) Davidson, J. L.; Preston, P. N. In Advances in Heterocyclic Chemistry; Katritzky, A. R., Ed.; Academic: New York, 1982; Vol. 30, pp 319-402.
54. For a recent review on the use of transition metals in the synthesis and functionalization of indoles, see: Hegedus, L. S. Angew. Chem. 1988, 100, 1147; Angew. Chem., Int. Ed. Engl. 1988, 27, 1113-1226.
55. For a recent review on the use of transition metals in the synthesis and functionalization of indoles, see: Hegedus, L. S. Angew. Chem. 1988, 100, 1147; Angew. Chem., Int. Ed. Engl. 1988, 27, 1113-1226.
56. For recent examples of palladium-assisted indole ring formation, see: (a) Samizu, K.; Ogasawara, K. Heterocycles 1995, 41, 1627. (b) Jeschke, T.; Wensbo, D.; Annby, U.; Gronowitz, S.; Cohen, L. Tetrahedron Lett. 1993, 34, 6471. (c) Larock, R. C.; Yum, E. K. J. Am. Chem. Soc. 1991, 713, 6689. (d) Rudisill, D.; Stille, J. K. J. Org. Chem. 1989, 54, 5856. (e) Arcadi, A; Cacchi, S.; Marinelli, F. Tetrahedron Lett. 1989, 30, 2581. (f) Iritani, K.; Matsubara, S.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1799. (g) Sakamoto, T.; Kondo, Y.; Iwashita, S.; Nagano, T.; Yamanaka, H. Chem. Pharm. Bull. 1988, 36, 1305. (h) Krolski, M. E.; Renaldo, A. F.; Rudisill, D. E.; Stille, J. K. J. Org. Chem. 1988, 53, 1170.
57. For recent examples of palladium-assisted indole ring formation, see: (a) Samizu, K.; Ogasawara, K. Heterocycles 1995, 41, 1627. (b) Jeschke, T.; Wensbo, D.; Annby, U.; Gronowitz, S.; Cohen, L. Tetrahedron Lett. 1993, 34, 6471. (c) Larock, R. C.; Yum, E. K. J. Am. Chem. Soc. 1991, 713, 6689. (d) Rudisill, D.; Stille, J. K. J. Org. Chem. 1989, 54, 5856. (e) Arcadi, A; Cacchi, S.; Marinelli, F. Tetrahedron Lett. 1989, 30, 2581. (f) Iritani, K.; Matsubara, S.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1799. (g) Sakamoto, T.; Kondo, Y.; Iwashita, S.; Nagano, T.; Yamanaka, H. Chem. Pharm. Bull. 1988, 36, 1305. (h) Krolski, M. E.; Renaldo, A. F.; Rudisill, D. E.; Stille, J. K. J. Org. Chem. 1988, 53, 1170.
58. For recent examples of palladium-assisted indole ring formation, see: (a) Samizu, K.; Ogasawara, K. Heterocycles 1995, 41, 1627. (b) Jeschke, T.; Wensbo, D.; Annby, U.; Gronowitz, S.; Cohen, L. Tetrahedron Lett. 1993, 34, 6471. (c) Larock, R. C.; Yum, E. K. J. Am. Chem. Soc. 1991, 713, 6689. (d) Rudisill, D.; Stille, J. K. J. Org. Chem. 1989, 54, 5856. (e) Arcadi, A; Cacchi, S.; Marinelli, F. Tetrahedron Lett. 1989, 30, 2581. (f) Iritani, K.; Matsubara, S.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1799. (g) Sakamoto, T.; Kondo, Y.; Iwashita, S.; Nagano, T.; Yamanaka, H. Chem. Pharm. Bull. 1988, 36, 1305. (h) Krolski, M. E.; Renaldo, A. F.; Rudisill, D. E.; Stille, J. K. J. Org. Chem. 1988, 53, 1170.
59. For recent examples of palladium-assisted indole ring formation, see: (a) Samizu, K.; Ogasawara, K. Heterocycles 1995, 41, 1627. (b) Jeschke, T.; Wensbo, D.; Annby, U.; Gronowitz, S.; Cohen, L. Tetrahedron Lett. 1993, 34, 6471. (c) Larock, R. C.; Yum, E. K. J. Am. Chem. Soc. 1991, 713, 6689. (d) Rudisill, D.; Stille, J. K. J. Org. Chem. 1989, 54, 5856. (e) Arcadi, A; Cacchi, S.; Marinelli, F. Tetrahedron Lett. 1989, 30, 2581. (f) Iritani, K.; Matsubara, S.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1799. (g) Sakamoto, T.; Kondo, Y.; Iwashita, S.; Nagano, T.; Yamanaka, H. Chem. Pharm. Bull. 1988, 36, 1305. (h) Krolski, M. E.; Renaldo, A. F.; Rudisill, D. E.; Stille, J. K. J. Org. Chem. 1988, 53, 1170.
60. For recent examples of palladium-assisted indole ring formation, see: (a) Samizu, K.; Ogasawara, K. Heterocycles 1995, 41, 1627. (b) Jeschke, T.; Wensbo, D.; Annby, U.; Gronowitz, S.; Cohen, L. Tetrahedron Lett. 1993, 34, 6471. (c) Larock, R. C.; Yum, E. K. J. Am. Chem. Soc. 1991, 713, 6689. (d) Rudisill, D.; Stille, J. K. J. Org. Chem. 1989, 54, 5856. (e) Arcadi, A; Cacchi, S.; Marinelli, F. Tetrahedron Lett. 1989, 30, 2581. (f) Iritani, K.; Matsubara, S.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1799. (g) Sakamoto, T.; Kondo, Y.; Iwashita, S.; Nagano, T.; Yamanaka, H. Chem. Pharm. Bull. 1988, 36, 1305. (h) Krolski, M. E.; Renaldo, A. F.; Rudisill, D. E.; Stille, J. K. J. Org. Chem. 1988, 53, 1170.
61. For recent examples of palladium-assisted indole ring formation, see: (a) Samizu, K.; Ogasawara, K. Heterocycles 1995, 41, 1627. (b) Jeschke, T.; Wensbo, D.; Annby, U.; Gronowitz, S.; Cohen, L. Tetrahedron Lett. 1993, 34, 6471. (c) Larock, R. C.; Yum, E. K. J. Am. Chem. Soc. 1991, 713, 6689. (d) Rudisill, D.; Stille, J. K. J. Org. Chem. 1989, 54, 5856. (e) Arcadi, A; Cacchi, S.; Marinelli, F. Tetrahedron Lett. 1989, 30, 2581. (f) Iritani, K.; Matsubara, S.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1799. (g) Sakamoto, T.; Kondo, Y.; Iwashita, S.; Nagano, T.; Yamanaka, H. Chem. Pharm. Bull. 1988, 36, 1305. (h) Krolski, M. E.; Renaldo, A. F.; Rudisill, D. E.; Stille, J. K. J. Org. Chem. 1988, 53, 1170.
62. For recent examples of palladium-assisted indole ring formation, see: (a) Samizu, K.; Ogasawara, K. Heterocycles 1995, 41, 1627. (b) Jeschke, T.; Wensbo, D.; Annby, U.; Gronowitz, S.; Cohen, L. Tetrahedron Lett. 1993, 34, 6471. (c) Larock, R. C.; Yum, E. K. J. Am. Chem. Soc. 1991, 713, 6689. (d) Rudisill, D.; Stille, J. K. J. Org. Chem. 1989, 54, 5856. (e) Arcadi, A; Cacchi, S.; Marinelli, F. Tetrahedron Lett. 1989, 30, 2581. (f) Iritani, K.; Matsubara, S.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1799. (g) Sakamoto, T.; Kondo, Y.; Iwashita, S.; Nagano, T.; Yamanaka, H. Chem. Pharm. Bull. 1988, 36, 1305. (h) Krolski, M. E.; Renaldo, A. F.; Rudisill, D. E.; Stille, J. K. J. Org. Chem. 1988, 53, 1170.
63. For recent examples of palladium-assisted indole ring formation, see: (a) Samizu, K.; Ogasawara, K. Heterocycles 1995, 41, 1627. (b) Jeschke, T.; Wensbo, D.; Annby, U.; Gronowitz, S.; Cohen, L. Tetrahedron Lett. 1993, 34, 6471. (c) Larock, R. C.; Yum, E. K. J. Am. Chem. Soc. 1991, 713, 6689. (d) Rudisill, D.; Stille, J. K. J. Org. Chem. 1989, 54, 5856. (e) Arcadi, A; Cacchi, S.; Marinelli, F. Tetrahedron Lett. 1989, 30, 2581. (f) Iritani, K.; Matsubara, S.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1799. (g) Sakamoto, T.; Kondo, Y.; Iwashita, S.; Nagano, T.; Yamanaka, H. Chem. Pharm. Bull. 1988, 36, 1305. (h) Krolski, M. E.; Renaldo, A. F.; Rudisill, D. E.; Stille, J. K. J. Org. Chem. 1988, 53, 1170.
64. For the ortho-substitution of aniline directed toward indole synthesis, see: (a) Chen, C.; Lieberman, D. R.; Larsen, R. D.; Reamer, R. A.; Verhoeven, T. R.; Reider, P. J.; Cottrell, I. F.; Houghton, P. G. Tetrahedron Lett. 1994, 35, 6981. (b) Taylor, E. C.; Katz, A. H.; Salgado-Zamora, H.; McKillop, A. Tetrahedron Lett. 1986, 26, 5963. (c) Larock, R. C.; Liu, C.-L.; Lau, H. H.; Varaprath, S. Tetrahedron Lett. 1984, 25, 4459. (d) Martin, P. Helv. Chim. Acta 1984, 67, 1647. (e) Blechert, S. Tetrahedron Lett. 1984, 25, 1547. (f) Sundberg, R. J.; Laurino, J. P. J. Org. Chem. 1984, 49, 249. (g) Fujiwara, J.; Fukutani, Y.; Sano, H.; Maruoka, K.; Yamamoto, H. J. Am. Chem. Soc. 1983, 105, 7177. (h) Sugasawa, T.; Adachi, M.; Sasakura, K.; Kitagawa, A. J. Org. Chem. 1979, 44, 578. (i) Makisumi, Y.; Takada, S. Chem. Pharm. Bull. 1976, 24, 770. (j) Gassman, P. G.; van Bergen, T. J.; Gilbert, D. P.; Berkeley, W.; Cue, W., Jr. J. Am. Chem. Soc. 1974, 96, 5495.
65. For the ortho-substitution of aniline directed toward indole synthesis, see: (a) Chen, C.; Lieberman, D. R.; Larsen, R. D.; Reamer, R. A.; Verhoeven, T. R.; Reider, P. J.; Cottrell, I. F.; Houghton, P. G. Tetrahedron Lett. 1994, 35, 6981. (b) Taylor, E. C.; Katz, A. H.; Salgado-Zamora, H.; McKillop, A. Tetrahedron Lett. 1986, 26, 5963. (c) Larock, R. C.; Liu, C.-L.; Lau, H. H.; Varaprath, S. Tetrahedron Lett. 1984, 25, 4459. (d) Martin, P. Helv. Chim. Acta 1984, 67, 1647. (e) Blechert, S. Tetrahedron Lett. 1984, 25, 1547. (f) Sundberg, R. J.; Laurino, J. P. J. Org. Chem. 1984, 49, 249. (g) Fujiwara, J.; Fukutani, Y.; Sano, H.; Maruoka, K.; Yamamoto, H. J. Am. Chem. Soc. 1983, 105, 7177. (h) Sugasawa, T.; Adachi, M.; Sasakura, K.; Kitagawa, A. J. Org. Chem. 1979, 44, 578. (i) Makisumi, Y.; Takada, S. Chem. Pharm. Bull. 1976, 24, 770. (j) Gassman,
66. For the ortho-substitution of aniline directed toward indole synthesis, see: (a) Chen, C.; Lieberman, D. R.; Larsen, R. D.; Reamer, R. A.; Verhoeven, T. R.; Reider, P. J.; Cottrell, I. F.; Houghton, P. G. Tetrahedron Lett. 1994, 35, 6981. (b) Taylor, E. C.; Katz, A. H.; Salgado-Zamora, H.; McKillop, A. Tetrahedron Lett. 1986, 26, 5963. (c) Larock, R. C.; Liu, C.-L.; Lau, H. H.; Varaprath, S. Tetrahedron Lett. 1984, 25, 4459. (d) Martin, P. Helv. Chim. Acta 1984, 67, 1647. (e) Blechert, S. Tetrahedron Lett. 1984, 25, 1547. (f) Sundberg, R. J.; Laurino, J. P. J. Org. Chem. 1984, 49, 249. (g) Fujiwara, J.; Fukutani, Y.; Sano, H.; Maruoka, K.; Yamamoto, H. J. Am. Chem. Soc. 1983, 105, 7177. (h) Sugasawa, T.; Adachi, M.; Sasakura, K.; Kitagawa, A. J. Org. Chem. 1979, 44, 578. (i) Makisumi, Y.; Takada, S. Chem. Pharm. Bull. 1976, 24, 770. (j) Gassman, P. G.; van Bergen, T. J.; Gilbert, D. P.; Berkeley, W.; Cue, W., Jr. J. Am. Chem. Soc. 1974, 96, 5495.
67. For the ortho-substitution of aniline directed toward indole synthesis, see: (a) Chen, C.; Lieberman, D. R.; Larsen, R. D.; Reamer, R. A.; Verhoeven, T. R.; Reider, P. J.; Cottrell, I. F.; Houghton, P. G. Tetrahedron Lett. 1994, 35, 6981. (b) Taylor, E. C.; Katz, A. H.; Salgado-Zamora, H.; McKillop, A. Tetrahedron Lett. 1986, 26, 5963. (c) Larock, R. C.; Liu, C.-L.; Lau, H. H.; Varaprath, S. Tetrahedron Lett. 1984, 25, 4459. (d) Martin, P. Helv. Chim. Acta 1984, 67, 1647. (e) Blechert, S. Tetrahedron Lett. 1984, 25, 1547. (f) Sundberg, R. J.; Laurino, J. P. J. Org. Chem. 1984, 49, 249. (g) Fujiwara, J.; Fukutani, Y.; Sano, H.; Maruoka, K.; Yamamoto, H. J. Am. Chem. Soc. 1983, 105, 7177. (h) Sugasawa, T.; Adachi, M.; Sasakura, K.; Kitagawa, A. J. Org. Chem. 1979, 44, 578. (i) Makisumi, Y.; Takada, S. Chem. Pharm. Bull. 1976, 24, 770. (j) Gassman, P. G.; van Bergen, T. J.; Gilbert, D. P.; Berkeley, W.; Cue, W., Jr. J. Am. Chem. Soc. 1974, 96, 5495.
68. For the ortho-substitution of aniline directed toward indole synthesis, see: (a) Chen, C.; Lieberman, D. R.; Larsen, R. D.; Reamer, R. A.; Verhoeven, T. R.; Reider, P. J.; Cottrell, I. F.; Houghton, P. G. Tetrahedron Lett. 1994, 35, 6981. (b) Taylor, E. C.; Katz, A. H.; Salgado-Zamora, H.; McKillop, A. Tetrahedron Lett. 1986, 26, 5963. (c) Larock, R. C.; Liu, C.-L.; Lau, H. H.; Varaprath, S. Tetrahedron Lett. 1984, 25, 4459. (d) Martin, P. Helv. Chim. Acta 1984, 67, 1647. (e) Blechert, S. Tetrahedron Lett. 1984, 25, 1547. (f) Sundberg, R. J.; Laurino, J. P. J. Org. Chem. 1984, 49, 249. (g) Fujiwara, J.; Fukutani, Y.; Sano, H.; Maruoka, K.; Yamamoto, H. J. Am. Chem. Soc. 1983, 105, 7177. (h) Sugasawa, T.; Adachi, M.; Sasakura, K.; Kitagawa, A. J. Org. Chem. 1979, 44, 578. (i) Makisumi, Y.; Takada, S. Chem. Pharm. Bull. 1976, 24, 770. (j) Gassman, P. G.; van Bergen, T. J.; Gilbert, D. P.; Berkeley, W.; Cue, W., Jr. J. Am. Chem. Soc. 1974, 96, 5495.
69. For the ortho-substitution of aniline directed toward indole synthesis, see: (a) Chen, C.; Lieberman, D. R.; Larsen, R. D.; Reamer, R. A.; Verhoeven, T. R.; Reider, P. J.; Cottrell, I. F.; Houghton, P. G. Tetrahedron Lett. 1994, 35, 6981. (b) Taylor, E. C.; Katz, A. H.; Salgado-Zamora, H.; McKillop, A. Tetrahedron Lett. 1986, 26, 5963. (c) Larock, R. C.; Liu, C.-L.; Lau, H. H.; Varaprath, S. Tetrahedron Lett. 1984, 25, 4459. (d) Martin, P. Helv. Chim. Acta 1984, 67, 1647. (e) Blechert, S. Tetrahedron Lett. 1984, 25, 1547. (f) Sundberg, R. J.; Laurino, J. P. J. Org. Chem. 1984, 49, 249. (g) Fujiwara, J.; Fukutani, Y.; Sano, H.; Maruoka, K.; Yamamoto, H. J. Am. Chem. Soc. 1983, 105, 7177. (h) Sugasawa, T.; Adachi, M.; Sasakura, K.; Kitagawa, A. J. Org. Chem. 1979, 44, 578. (i) Makisumi, Y.; Takada, S. Chem. Pharm. Bull. 1976, 24, 770. (j) Gassman, P. G.; van Bergen, T. J.; Gilbert, D. P.; Berkeley, W.; Cue, W., Jr. J. Am. Chem. Soc. 1974, 96, 5495.
70. For the ortho-substitution of aniline directed toward indole synthesis, see: (a) Chen, C.; Lieberman, D. R.; Larsen, R. D.; Reamer, R. A.; Verhoeven, T. R.; Reider, P. J.; Cottrell, I. F.; Houghton, P. G. Tetrahedron Lett. 1994, 35, 6981. (b) Taylor, E. C.; Katz, A. H.; Salgado-Zamora, H.; McKillop, A. Tetrahedron Lett. 1986, 26, 5963. (c) Larock, R. C.; Liu, C.-L.; Lau, H. H.; Varaprath, S. Tetrahedron Lett. 1984, 25, 4459. (d) Martin, P. Helv. Chim. Acta 1984, 67, 1647. (e) Blechert, S. Tetrahedron Lett. 1984, 25, 1547. (f) Sundberg, R. J.; Laurino, J. P. J. Org. Chem. 1984, 49, 249. (g) Fujiwara, J.; Fukutani, Y.; Sano, H.; Maruoka, K.; Yamamoto, H. J. Am. Chem. Soc. 1983, 105, 7177. (h) Sugasawa, T.; Adachi, M.; Sasakura, K.; Kitagawa, A. J. Org. Chem. 1979, 44, 578. (i) Makisumi, Y.; Takada, S. Chem. Pharm. Bull. 1976, 24, 770. (j) Gassman, P. G.; van Bergen, T. J.; Gilbert, D. P.; Berkeley, W.; Cue, W., Jr. J. Am. Chem. Soc. 1974, 96, 5495.
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