Palladium-catalyzed synthesis of 5- and 5,7-substituted indole derivatives

Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry

Volumn 38, Issue 8, 1999, Pages 897-904

  Yang, Shyh Chyun ^a   Chung, Wen Hung ^a  

^a KAOHSIUNG MEDICAL UNIVERSITY   (Taiwan)

Author keywords

[No Author keywords available]

Indexed keywords

INDOLE DERIVATIVE;

ARTICLE; CATALYSIS; CATALYST; CHEMICAL ANALYSIS; CHEMICAL REACTION; CHEMICAL STRUCTURE; CYCLIZATION; SYNTHESIS;

EID: 0033505723     PISSN: 03764699     EISSN: None     Source Type: Journal    
DOI: None     Document Type: Article

References (53)

1. Manske R H F, The Alkaloids, Vol 1-17, (Wiley, New York), 1950-1979; Hesse M, Indolalkaloids in Tabellen (Springer, Berlin), 1964; Glasby J S, Encyclopedia of the Alkaloids (Plenum Press, New York), 1975.
2. Manske R H F, The Alkaloids, Vol 1-17, (Wiley, New York), 1950-1979; Hesse M, Indolalkaloids in Tabellen (Springer, Berlin), 1964; Glasby J S, Encyclopedia of the Alkaloids (Plenum Press, New York), 1975.
3. Manske R H F, The Alkaloids, Vol 1-17, (Wiley, New York), 1950-1979; Hesse M, Indolalkaloids in Tabellen (Springer, Berlin), 1964; Glasby J S, Encyclopedia of the Alkaloids (Plenum Press, New York), 1975.
4. Sundberg R J, In Comprehensive Heterocyclic Chemistry, edited by W B Clive & G W H Cheeseman (Pergamon, Oxford), 4, 1984, p 313-368; Pindur U & Adam R, J Heterocycl Chem, 25, 1988, 1.
5. Sundberg R J, In Comprehensive Heterocyclic Chemistry, edited by W B Clive & G W H Cheeseman (Pergamon, Oxford), 4, 1984, p 313-368; Pindur U & Adam R, J Heterocycl Chem, 25, 1988, 1.
6. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
7. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
8. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
9. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
10. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
11. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
12. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
13. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
14. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
15. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
16. 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 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: Labadie S S & Teng E, J Org Chem, 59, 1994, 4250; Palmisano G & Santagostino M, Synlett, 1993, 771; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Heterocycles, 36, 1993, 941; Kondo Y, Takazawa N, Yoshida A & Sakamoto T, J Chem Soc Perkin Trans 1, 1995, 1207; Ciattini G, Morera E & Ortar G, Tetrahedron Lett, 35, 1994, 2405; Amat M, Hadida S & Bosch J, Tetrahedron Lett, 35, 1994 793 and references therein; Sakamoto T, Kondo Y, Takazawa N & Yamanaka H, Tetrahedron Lett, 34, 1993, 5955; Yokoyama Y, Ikeda M, Saito M, Yoda T, Suzuki H & Murakami Y, Heterocycles, 31, 1990, 1505. Substitution at C-4: Iwao M, Heterocycles, 36, 1993, 29; Sermmelhack M F, Knochel P & Singleton T, Tetrahedron Lett, 34, 1993, 5051 and references therein; Somei M, Ohta T, Shinoda J & Somada Y, Heterocycles, 29, 1989, 653. Substitution at C-3/C-4: Iwao M & Motoi O, Tetrahedron Lett, 36, 1995, 5929; Tidwell J, Peat A J & Buchwald S L, J Org Chem, 59, 1994, 7164; Hegedus L S, Sestrick M R, Michaelson E T & Harrington P J, J Org Chem, 54, 1989, 4141 and references therein. Substitution at C-4/C-5 and C-5/C-6: Griffen E J, Roe D G & Snieckus V, J Org Chem, 60, 1995, 1484. Substitution at C-6: Hirano S, Akai R, Shinoda Y & Nakatsuka S, Heterocycles, 41, 1995, 255; Telanishi K, Nakatsuka S & Goto T, Synthesis, 1994, 1018; Nakatsuka S, Telanishi K & Goto T, Tetrahedron Lett, 35, 1994, 2699. Substitution at C-7: Carrera G M & Sheppard G S, Synlett, 1994, 93; Somei M, Yamada F, Hamada H & Kawasaki T, Heterocycles, 29, 1989, 643; Somei M & Saida Y, Heterocycles, 23, 1985, 3113.
27. See, for instance: Tietze L F & Buhr W, Angew Chem, 107, 1995, 1485; Angew Chem Int Ed Engl, 34, 1995,1366; Boger D L, Acc Chem Res, 28, 1995, 20; Tidwell J & Buchwald S L, J Am Chem Soc, 116, 1994, 11797; Fukuyama T & Chen X, J Am Chem Soc, 116, 1994, 3125; Tietze L F & Grote T, J Org Chem, 59, 1994, 192.
28. See, for instance: Tietze L F & Buhr W, Angew Chem, 107, 1995, 1485; Angew Chem Int Ed Engl, 34, 1995,1366; Boger D L, Acc Chem Res, 28, 1995, 20; Tidwell J & Buchwald S L, J Am Chem Soc, 116, 1994, 11797; Fukuyama T & Chen X, J Am Chem Soc, 116, 1994, 3125; Tietze L F & Grote T, J Org Chem, 59, 1994, 192.
29. See, for instance: Tietze L F & Buhr W, Angew Chem, 107, 1995, 1485; Angew Chem Int Ed Engl, 34, 1995,1366; Boger D L, Acc Chem Res, 28, 1995, 20; Tidwell J & Buchwald S L, J Am Chem Soc, 116, 1994, 11797; Fukuyama T & Chen X, J Am Chem Soc, 116, 1994, 3125; Tietze L F & Grote T, J Org Chem, 59, 1994, 192.
30. See, for instance: Tietze L F & Buhr W, Angew Chem, 107, 1995, 1485; Angew Chem Int Ed Engl, 34, 1995,1366; Boger D L, Acc Chem Res, 28, 1995, 20; Tidwell J & Buchwald S L, J Am Chem Soc, 116, 1994, 11797; Fukuyama T & Chen X, J Am Chem Soc, 116, 1994, 3125; Tietze L F & Grote T, J Org Chem, 59, 1994, 192.
31. See, for instance: Tietze L F & Buhr W, Angew Chem, 107, 1995, 1485; Angew Chem Int Ed Engl, 34, 1995,1366; Boger D L, Acc Chem Res, 28, 1995, 20; Tidwell J & Buchwald S L, J Am Chem Soc, 116, 1994, 11797; Fukuyama T & Chen X, J Am Chem Soc, 116, 1994, 3125; Tietze L F & Grote T, J Org Chem, 59, 1994, 192.
32. See, for instance: Tietze L F & Buhr W, Angew Chem, 107, 1995, 1485; Angew Chem Int Ed Engl, 34, 1995,1366; Boger D L, Acc Chem Res, 28, 1995, 20; Tidwell J & Buchwald S L, J Am Chem Soc, 116, 1994, 11797; Fukuyama T & Chen X, J Am Chem Soc, 116, 1994, 3125; Tietze L F & Grote T, J Org Chem, 59, 1994, 192.
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36. For recent examples of palladium-assisted indole ring formation, see: Samizu K & Ogasawara K, Heterocycles, 41, 1995, 1627; Jeschke T, Wensbo D, Annby U, Gronowitz S & Cohen L, Tetrahedron Lett, 34, 1993, 6471; Larock R C & Yum E K, J Am Chem Soc, 113, 1991, 6689; Rudisill D & Stille J K, J Org Chem, 54, 1989, 5856; Arcadi A, Cacchi S & Marinelli F, Tetrahedron Lett, 30, 1989, 2581; Iritani K, Matsubara S & Utimoto K, Tetrahedron Lett, 29, 1988, 1799; Sakamoto T, Kondo Y, Iwashita S, Nagano T & Yamanaka H, Chem Pharm Bull, 36, 1988, 1305; Krolski M E, Renaldo A F, Rudisill D E & Stille J K, J Org Chem, 53, 1988, 1170.
37. For recent examples of palladium-assisted indole ring formation, see: Samizu K & Ogasawara K, Heterocycles, 41, 1995, 1627; Jeschke T, Wensbo D, Annby U, Gronowitz S & Cohen L, Tetrahedron Lett, 34, 1993, 6471; Larock R C & Yum E K, J Am Chem Soc, 113, 1991, 6689; Rudisill D & Stille J K, J Org Chem, 54, 1989, 5856; Arcadi A, Cacchi S & Marinelli F, Tetrahedron Lett, 30, 1989, 2581; Iritani K, Matsubara S & Utimoto K, Tetrahedron Lett, 29, 1988, 1799; Sakamoto T, Kondo Y, Iwashita S, Nagano T & Yamanaka H, Chem Pharm Bull, 36, 1988, 1305; Krolski M E, Renaldo A F, Rudisill D E & Stille J K, J Org Chem, 53, 1988, 1170.
38. For recent examples of palladium-assisted indole ring formation, see: Samizu K & Ogasawara K, Heterocycles, 41, 1995, 1627; Jeschke T, Wensbo D, Annby U, Gronowitz S & Cohen L, Tetrahedron Lett, 34, 1993, 6471; Larock R C & Yum E K, J Am Chem Soc, 113, 1991, 6689; Rudisill D & Stille J K, J Org Chem, 54, 1989, 5856; Arcadi A, Cacchi S & Marinelli F, Tetrahedron Lett, 30, 1989, 2581; Iritani K, Matsubara S & Utimoto K, Tetrahedron Lett, 29, 1988, 1799; Sakamoto T, Kondo Y, Iwashita S, Nagano T & Yamanaka H, Chem Pharm Bull, 36, 1988, 1305; Krolski M E, Renaldo A F, Rudisill D E & Stille J K, J Org Chem, 53, 1988, 1170.
39. For recent examples of palladium-assisted indole ring formation, see: Samizu K & Ogasawara K, Heterocycles, 41, 1995, 1627; Jeschke T, Wensbo D, Annby U, Gronowitz S & Cohen L, Tetrahedron Lett, 34, 1993, 6471; Larock R C & Yum E K, J Am Chem Soc, 113, 1991, 6689; Rudisill D & Stille J K, J Org Chem, 54, 1989, 5856; Arcadi A, Cacchi S & Marinelli F, Tetrahedron Lett, 30, 1989, 2581; Iritani K, Matsubara S & Utimoto K, Tetrahedron Lett, 29, 1988, 1799; Sakamoto T, Kondo Y, Iwashita S, Nagano T & Yamanaka H, Chem Pharm Bull, 36, 1988, 1305; Krolski M E, Renaldo A F, Rudisill D E & Stille J K, J Org Chem, 53, 1988, 1170.
40. For recent examples of palladium-assisted indole ring formation, see: Samizu K & Ogasawara K, Heterocycles, 41, 1995, 1627; Jeschke T, Wensbo D, Annby U, Gronowitz S & Cohen L, Tetrahedron Lett, 34, 1993, 6471; Larock R C & Yum E K, J Am Chem Soc, 113, 1991, 6689; Rudisill D & Stille J K, J Org Chem, 54, 1989, 5856; Arcadi A, Cacchi S & Marinelli F, Tetrahedron Lett, 30, 1989, 2581; Iritani K, Matsubara S & Utimoto K, Tetrahedron Lett, 29, 1988, 1799; Sakamoto T, Kondo Y, Iwashita S, Nagano T & Yamanaka H, Chem Pharm Bull, 36, 1988, 1305; Krolski M E, Renaldo A F, Rudisill D E & Stille J K, J Org Chem, 53, 1988, 1170.
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