1,3-dipolar cycloaddition between hetaryl nitrones and methyl acrylate: Theoretical study and application to the synthesis of functionalized pyrrolidines

Heterocycles

Volumn 53, Issue 4, 2000, Pages 861-875

  Merino, Pedro ^a   Anoro, Sonia ^a   Merchan, Francisco ^a   Tejero, Tomas ^a  

^a UNIVERSITY OF ZARAGOZA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

NITRONE DERIVATIVE; PYRROLIDINE DERIVATIVE;

ARTICLE; QUALITATIVE DIAGNOSIS; QUANTUM CHEMISTRY; REACTION ANALYSIS; STEREOCHEMISTRY; STRUCTURE ANALYSIS; SYNTHESIS;

EID: 0034177426     PISSN: 03855414     EISSN: None     Source Type: Journal    
DOI: 10.3987/COM-99-8826     Document Type: Article

References (74)

1. J. P. Michael, Natural Prod. Rep., 1997, 14, 619; ibid., 1995, 12, 535; ibid., 1993, 10, 51; J. Steele, Contemp. Org. Synth., 1994, 1, 95; K. Burguess and I. Henderson, Tetrahedron, 1992, 48, 4045.
2. J. P. Michael, Natural Prod. Rep., 1997, 14, 619; ibid., 1995, 12, 535; ibid., 1993, 10, 51; J. Steele, Contemp. Org. Synth., 1994, 1, 95; K. Burguess and I. Henderson, Tetrahedron, 1992, 48, 4045.
3. J. P. Michael, Natural Prod. Rep., 1997, 14, 619; ibid., 1995, 12, 535; ibid., 1993, 10, 51; J. Steele, Contemp. Org. Synth., 1994, 1, 95; K. Burguess and I. Henderson, Tetrahedron, 1992, 48, 4045.
4. J. P. Michael, Natural Prod. Rep., 1997, 14, 619; ibid., 1995, 12, 535; ibid., 1993, 10, 51; J. Steele, Contemp. Org. Synth., 1994, 1, 95; K. Burguess and I. Henderson, Tetrahedron, 1992, 48, 4045.
5. J. P. Michael, Natural Prod. Rep., 1997, 14, 619; ibid., 1995, 12, 535; ibid., 1993, 10, 51; J. Steele, Contemp. Org. Synth., 1994, 1, 95; K. Burguess and I. Henderson, Tetrahedron, 1992, 48, 4045.
6. D. O'Hagan, Natural Prod. Rep., 1997, 14, 637 and references cited therein; W.-R. Li, S.-Y. Han, and M. M. Joullie, Heterocycles, 1993, 36, 359; M. Takebayashi, S. Hiranuma, Y. Kanie, T. Kjimoto, O. Kanie, and C.-H. Wong, J. Org. Chem., 1999, 64, 5280 and references cited therein.
7. D. O'Hagan, Natural Prod. Rep., 1997, 14, 637 and references cited therein; W.-R. Li, S.-Y. Han, and M. M. Joullie, Heterocycles, 1993, 36, 359; M. Takebayashi, S. Hiranuma, Y. Kanie, T. Kjimoto, O. Kanie, and C.-H. Wong, J. Org. Chem., 1999, 64, 5280 and references cited therein.
8. D. O'Hagan, Natural Prod. Rep., 1997, 14, 637 and references cited therein; W.-R. Li, S.-Y. Han, and M. M. Joullie, Heterocycles, 1993, 36, 359; M. Takebayashi, S. Hiranuma, Y. Kanie, T. Kjimoto, O. Kanie, and C.-H. Wong, J. Org. Chem., 1999, 64, 5280 and references cited therein.
9. W.-J. Koot, H. Hiemstra, and W. N. Speckamp, J. Org. Chem., 1992, 57, 1059; T. Ohta, A. Hosoi, and S. Nozoe, Tetrahedron Lett., 1988, 29, 329; H. de Koning, H. Hiemstra, M. J. Moolenaar, and W. N. Speckamp, Eur. J. Org. Chem., 1998, 1792; P. Q. Huang, S. L. Wang, J. L. Ye, Y. P. Ruan, Y. Q. Huang, H. Zheng, and J. X. Gao, Tetrahedron, 1998, 54, 12547; J. Heinz, W. H. W. Lunn, R. E. Murff, J. W. Paschal, and L. A. Spangle, J. Org. Chem., 1996, 61, 4838. For a review on the synthetic utility of 5-substituted 2-pyrrolidinones see: C. Najera and M. Yus, Tetrahedron: Asymmetry, 1999, 10, 2245.
10. W.-J. Koot, H. Hiemstra, and W. N. Speckamp, J. Org. Chem., 1992, 57, 1059; T. Ohta, A. Hosoi, and S. Nozoe, Tetrahedron Lett., 1988, 29, 329; H. de Koning, H. Hiemstra, M. J. Moolenaar, and W. N. Speckamp, Eur. J. Org. Chem., 1998, 1792; P. Q. Huang, S. L. Wang, J. L. Ye, Y. P. Ruan, Y. Q. Huang, H. Zheng, and J. X. Gao, Tetrahedron, 1998, 54, 12547; J. Heinz, W. H. W. Lunn, R. E. Murff, J. W. Paschal, and L. A. Spangle, J. Org. Chem., 1996, 61, 4838. For a review on the synthetic utility of 5-substituted 2-pyrrolidinones see: C. Najera and M. Yus, Tetrahedron: Asymmetry, 1999, 10, 2245.
11. W.-J. Koot, H. Hiemstra, and W. N. Speckamp, J. Org. Chem., 1992, 57, 1059; T. Ohta, A. Hosoi, and S. Nozoe, Tetrahedron Lett., 1988, 29, 329; H. de Koning, H. Hiemstra, M. J. Moolenaar, and W. N. Speckamp, Eur. J. Org. Chem., 1998, 1792; P. Q. Huang, S. L. Wang, J. L. Ye, Y. P. Ruan, Y. Q. Huang, H. Zheng, and J. X. Gao, Tetrahedron, 1998, 54, 12547; J. Heinz, W. H. W. Lunn, R. E. Murff, J. W. Paschal, and L. A. Spangle, J. Org. Chem., 1996, 61, 4838. For a review on the synthetic utility of 5-substituted 2-pyrrolidinones see: C. Najera and M. Yus, Tetrahedron: Asymmetry, 1999, 10, 2245.
12. W.-J. Koot, H. Hiemstra, and W. N. Speckamp, J. Org. Chem., 1992, 57, 1059; T. Ohta, A. Hosoi, and S. Nozoe, Tetrahedron Lett., 1988, 29, 329; H. de Koning, H. Hiemstra, M. J. Moolenaar, and W. N. Speckamp, Eur. J. Org. Chem., 1998, 1792; P. Q. Huang, S. L. Wang, J. L. Ye, Y. P. Ruan, Y. Q. Huang, H. Zheng, and J. X. Gao, Tetrahedron, 1998, 54, 12547; J. Heinz, W. H. W. Lunn, R. E. Murff, J. W. Paschal, and L. A. Spangle, J. Org. Chem., 1996, 61, 4838. For a review on the synthetic utility of 5-substituted 2-pyrrolidinones see: C. Najera and M. Yus, Tetrahedron: Asymmetry, 1999, 10, 2245.
13. W.-J. Koot, H. Hiemstra, and W. N. Speckamp, J. Org. Chem., 1992, 57, 1059; T. Ohta, A. Hosoi, and S. Nozoe, Tetrahedron Lett., 1988, 29, 329; H. de Koning, H. Hiemstra, M. J. Moolenaar, and W. N. Speckamp, Eur. J. Org. Chem., 1998, 1792; P. Q. Huang, S. L. Wang, J. L. Ye, Y. P. Ruan, Y. Q. Huang, H. Zheng, and J. X. Gao, Tetrahedron, 1998, 54, 12547; J. Heinz, W. H. W. Lunn, R. E. Murff, J. W. Paschal, and L. A. Spangle, J. Org. Chem., 1996, 61, 4838. For a review on the synthetic utility of 5-substituted 2-pyrrolidinones see: C. Najera and M. Yus, Tetrahedron: Asymmetry, 1999, 10, 2245.
14. W.-J. Koot, H. Hiemstra, and W. N. Speckamp, J. Org. Chem., 1992, 57, 1059; T. Ohta, A. Hosoi, and S. Nozoe, Tetrahedron Lett., 1988, 29, 329; H. de Koning, H. Hiemstra, M. J. Moolenaar, and W. N. Speckamp, Eur. J. Org. Chem., 1998, 1792; P. Q. Huang, S. L. Wang, J. L. Ye, Y. P. Ruan, Y. Q. Huang, H. Zheng, and J. X. Gao, Tetrahedron, 1998, 54, 12547; J. Heinz, W. H. W. Lunn, R. E. Murff, J. W. Paschal, and L. A. Spangle, J. Org. Chem., 1996, 61, 4838. For a review on the synthetic utility of 5-substituted 2-pyrrolidinones see: C. Najera and M. Yus, Tetrahedron: Asymmetry, 1999, 10, 2245.
15. Y. J. Kim, A. Takatsuki, N. Kogoshi, and T. Kitahara, Tetrahedron, 1999, 55, 8353; N. Langlois, Tetrahedron: Asymmetry, 1998, 9, 1333; W. G. B. van Henegouwen and H. Hiemstra, J. Org. Chem., 1997, 62, 8862; G. Rassu, L. Pinna, P. Spanu, F. Ulgheri, and G. Casiraghi, Tetrahedron Lett., 1994, 35, 4019; K.-H. Altmann Tetrahedron Lett., 1993, 34, 7221.
16. Y. J. Kim, A. Takatsuki, N. Kogoshi, and T. Kitahara, Tetrahedron, 1999, 55, 8353; N. Langlois, Tetrahedron: Asymmetry, 1998, 9, 1333; W. G. B. van Henegouwen and H. Hiemstra, J. Org. Chem., 1997, 62, 8862; G. Rassu, L. Pinna, P. Spanu, F. Ulgheri, and G. Casiraghi, Tetrahedron Lett., 1994, 35, 4019; K.-H. Altmann Tetrahedron Lett., 1993, 34, 7221.
17. Y. J. Kim, A. Takatsuki, N. Kogoshi, and T. Kitahara, Tetrahedron, 1999, 55, 8353; N. Langlois, Tetrahedron: Asymmetry, 1998, 9, 1333; W. G. B. van Henegouwen and H. Hiemstra, J. Org. Chem., 1997, 62, 8862; G. Rassu, L. Pinna, P. Spanu, F. Ulgheri, and G. Casiraghi, Tetrahedron Lett., 1994, 35, 4019; K.-H. Altmann Tetrahedron Lett., 1993, 34, 7221.
18. Y. J. Kim, A. Takatsuki, N. Kogoshi, and T. Kitahara, Tetrahedron, 1999, 55, 8353; N. Langlois, Tetrahedron: Asymmetry, 1998, 9, 1333; W. G. B. van Henegouwen and H. Hiemstra, J. Org. Chem., 1997, 62, 8862; G. Rassu, L. Pinna, P. Spanu, F. Ulgheri, and G. Casiraghi, Tetrahedron Lett., 1994, 35, 4019; K.-H. Altmann Tetrahedron Lett., 1993, 34, 7221.
19. Y. J. Kim, A. Takatsuki, N. Kogoshi, and T. Kitahara, Tetrahedron, 1999, 55, 8353; N. Langlois, Tetrahedron: Asymmetry, 1998, 9, 1333; W. G. B. van Henegouwen and H. Hiemstra, J. Org. Chem., 1997, 62, 8862; G. Rassu, L. Pinna, P. Spanu, F. Ulgheri, and G. Casiraghi, Tetrahedron Lett., 1994, 35, 4019; K.-H. Altmann Tetrahedron Lett., 1993, 34, 7221.
20. C. Pedregal, J. Ezquerra, A. Escribano, M. C. Carreno, and J. L. Garcia-Ruano, Tetrahedron Lett., 1994, 35, 2053; K.-C. Woo and K. Jones, Tetrahedron Lett., 1991, 32, 6949; O. Calvez, A. Chiaroni, and N. Langlois, Tetrahedron Lett., 1998, 39, 9447. A. Rubio, J. Ezquerra, A. Escribano, M. J. Remuinan, and J. J. Vaquero, Tetrahedron Lett., 1998, 39, 2171; B. Dudot, L. Micouin, I. Baussanne, and J. Royer, Synthesis, 1999, 688.
21. C. Pedregal, J. Ezquerra, A. Escribano, M. C. Carreno, and J. L. Garcia-Ruano, Tetrahedron Lett., 1994, 35, 2053; K.-C. Woo and K. Jones, Tetrahedron Lett., 1991, 32, 6949; O. Calvez, A. Chiaroni, and N. Langlois, Tetrahedron Lett., 1998, 39, 9447. A. Rubio, J. Ezquerra, A. Escribano, M. J. Remuinan, and J. J. Vaquero, Tetrahedron Lett., 1998, 39, 2171; B. Dudot, L. Micouin, I. Baussanne, and J. Royer, Synthesis, 1999, 688.
22. C. Pedregal, J. Ezquerra, A. Escribano, M. C. Carreno, and J. L. Garcia-Ruano, Tetrahedron Lett., 1994, 35, 2053; K.-C. Woo and K. Jones, Tetrahedron Lett., 1991, 32, 6949; O. Calvez, A. Chiaroni, and N. Langlois, Tetrahedron Lett., 1998, 39, 9447. A. Rubio, J. Ezquerra, A. Escribano, M. J. Remuinan, and J. J. Vaquero, Tetrahedron Lett., 1998, 39, 2171; B. Dudot, L. Micouin, I. Baussanne, and J. Royer, Synthesis, 1999, 688.
23. C. Pedregal, J. Ezquerra, A. Escribano, M. C. Carreno, and J. L. Garcia-Ruano, Tetrahedron Lett., 1994, 35, 2053; K.-C. Woo and K. Jones, Tetrahedron Lett., 1991, 32, 6949; O. Calvez, A. Chiaroni, and N. Langlois, Tetrahedron Lett., 1998, 39, 9447. A. Rubio, J. Ezquerra, A. Escribano, M. J. Remuinan, and J. J. Vaquero, Tetrahedron Lett., 1998, 39, 2171; B. Dudot, L. Micouin, I. Baussanne, and J. Royer, Synthesis, 1999, 688.
24. C. Pedregal, J. Ezquerra, A. Escribano, M. C. Carreno, and J. L. Garcia-Ruano, Tetrahedron Lett., 1994, 35, 2053; K.-C. Woo and K. Jones, Tetrahedron Lett., 1991, 32, 6949; O. Calvez, A. Chiaroni, and N. Langlois, Tetrahedron Lett., 1998, 39, 9447. A. Rubio, J. Ezquerra, A. Escribano, M. J. Remuinan, and J. J. Vaquero, Tetrahedron Lett., 1998, 39, 2171; B. Dudot, L. Micouin, I. Baussanne, and J. Royer, Synthesis, 1999, 688.
25. N. Ikota, H. Nakagawa, S. Ohno, K. Noguchi, and K. Okuyama, Tetrahedron, 1998, 54, 8985; J. V. Betsbrugge, W. V. D. Nest, P. Verheyden, and D. Tourwe, Tetrahedron, 1998, 54, 1753; H. Yoda, M. Kawauchi, and K. Takabe, Synlett, 1998, 137. H. Yoda, H. Yamazaki, and K. Takabe, Tetrahedron: Asymmetry, 1996, 7, 373.
26. N. Ikota, H. Nakagawa, S. Ohno, K. Noguchi, and K. Okuyama, Tetrahedron, 1998, 54, 8985; J. V. Betsbrugge, W. V. D. Nest, P. Verheyden, and D. Tourwe, Tetrahedron, 1998, 54, 1753; H. Yoda, M. Kawauchi, and K. Takabe, Synlett, 1998, 137. H. Yoda, H. Yamazaki, and K. Takabe, Tetrahedron: Asymmetry, 1996, 7, 373.
27. N. Ikota, H. Nakagawa, S. Ohno, K. Noguchi, and K. Okuyama, Tetrahedron, 1998, 54, 8985; J. V. Betsbrugge, W. V. D. Nest, P. Verheyden, and D. Tourwe, Tetrahedron, 1998, 54, 1753; H. Yoda, M. Kawauchi, and K. Takabe, Synlett, 1998, 137. H. Yoda, H. Yamazaki, and K. Takabe, Tetrahedron: Asymmetry, 1996, 7, 373.
28. N. Ikota, H. Nakagawa, S. Ohno, K. Noguchi, and K. Okuyama, Tetrahedron, 1998, 54, 8985; J. V. Betsbrugge, W. V. D. Nest, P. Verheyden, and D. Tourwe, Tetrahedron, 1998, 54, 1753; H. Yoda, M. Kawauchi, and K. Takabe, Synlett, 1998, 137. H. Yoda, H. Yamazaki, and K. Takabe, Tetrahedron: Asymmetry, 1996, 7, 373.
29. M. J. Blanco and F. J. Sardina, J. Org. Chem., 1996, 61, 4748; M. J. Blanco and F. J. Sardina, Tetrahedron Lett., 1994,35, 8493; R. Sharma and W. D. Lubell, J. Org. Chem., 1996, 61, 202.
30. M. J. Blanco and F. J. Sardina, J. Org. Chem., 1996, 61, 4748; M. J. Blanco and F. J. Sardina, Tetrahedron Lett., 1994,35, 8493; R. Sharma and W. D. Lubell, J. Org. Chem., 1996, 61, 202.
31. M. J. Blanco and F. J. Sardina, J. Org. Chem., 1996, 61, 4748; M. J. Blanco and F. J. Sardina, Tetrahedron Lett., 1994,35, 8493; R. Sharma and W. D. Lubell, J. Org. Chem., 1996, 61, 202.
32. L. Demange, A. Menez, and C. Dugave, Tetrahedron Lett., 1998, 39, 1169; M. L. Peterson and R. Vince, J. Med. Chem. 1991, 34, 2787; G. Lowe, T. Vilaivan, J. Chem. Soc., Perkin Trans. 1, 1997, 547.
33. L. Demange, A. Menez, and C. Dugave, Tetrahedron Lett., 1998, 39, 1169; M. L. Peterson and R. Vince, J. Med. Chem. 1991, 34, 2787; G. Lowe, T. Vilaivan, J. Chem. Soc., Perkin Trans. 1, 1997, 547.
34. L. Demange, A. Menez, and C. Dugave, Tetrahedron Lett., 1998, 39, 1169; M. L. Peterson and R. Vince, J. Med. Chem. 1991, 34, 2787; G. Lowe, T. Vilaivan, J. Chem. Soc., Perkin Trans. 1, 1997, 547.
35. F. Zanardi, L. Battistini, M. Nespi, G. Rassu, P. Spanu, M. Cornia, and G. Casiraghi, Tetrahedron: Asymmetry, 1996, 7, 1167; P. Spanu, G. Rassu, F. Ulgheri, F. Zanardi, L. Battistini, and G. Casiraghi, Tetrahedron, 1996, 52, 4829; P. Soro, G. Rasu, P. Spanu, L. Pinna, F. Zanardi, and G. Casiraghi, J. Org. Chem., 1996, 61, 5172.
36. F. Zanardi, L. Battistini, M. Nespi, G. Rassu, P. Spanu, M. Cornia, and G. Casiraghi, Tetrahedron: Asymmetry, 1996, 7, 1167; P. Spanu, G. Rassu, F. Ulgheri, F. Zanardi, L. Battistini, and G. Casiraghi, Tetrahedron, 1996, 52, 4829; P. Soro, G. Rasu, P. Spanu, L. Pinna, F. Zanardi, and G. Casiraghi, J. Org. Chem., 1996, 61, 5172.
37. F. Zanardi, L. Battistini, M. Nespi, G. Rassu, P. Spanu, M. Cornia, and G. Casiraghi, Tetrahedron: Asymmetry, 1996, 7, 1167; P. Spanu, G. Rassu, F. Ulgheri, F. Zanardi, L. Battistini, and G. Casiraghi, Tetrahedron, 1996, 52, 4829; P. Soro, G. Rasu, P. Spanu, L. Pinna, F. Zanardi, and G. Casiraghi, J. Org. Chem., 1996, 61, 5172.
38. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
39. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
40. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
41. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
42. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
43. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
44. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
45. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
46. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
47. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
48. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
49. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
50. P. J. Smith, D. J. Soose, and C. S. Wilcox, J. Am. Chem. Soc., 1991, 113, 7412; T. Shimo, K. Somekavva, and O. Tsuge, J. Heterocycl. Chem., 1992, 29, 927; T. Minami, T. Isonaka, Y. Okada, and J. Ichikawa, J. Org. Chem., 1993, 58, 7009; A. B. holmes, A. B. Hughes, and A. L. Smith, J. Chem. Soc., Perkin Trans. 1, 1993, 633 ; P. Herczegh, I. Kovacs, L. Szilagyi, T. Varga, Z. Dinya, and F. Sztaricskai, Tetrahedron Lett., 1993, 34, 1211; Y. M. Goo, M. H. Soo, and Y.Y. Lee, Bull. Kor. Chem. Soc., 1996, 17, 909; S. A. Ali, J. H. Khan, and M. I. M. Wazeer, Tetrahedron, 1988, 44, 5911; P. DeShong and J. M. Leginus, J. Am. Chem. Soc., 1983, 105, 1686; J. D. White, R. A. Badger, H. S. Kezar III, A. J. Pallenberg, and G. A. Schiehser, Tetrahedron, 1989, 45, 6631; G. A. Schiehser, J. D. White, G. Matsumoto, J. O. Pezzanite, and J. Clardy, Tetrahedron Lett., 1986, 27, 5587. For reviews on cycloaddition chemistry of nitrones see: D. S. C. Black, R.F. Crozier, and C.V. Davis, Synthesis, 1975, 205; J.J. Tuffariello in "1,3-Dipolar Cycloaddition Chemistry", ed. by A. Padwa, John Wiley & Sons, New York, 1984, Vol. 2, pp. 83-168; P. N. Confalone and E. M. Huie, Org. React. 1988, 36, 1.
51. E. Coutouli-Argyropoulou, E. Malamidou-Xenikaki, X. N. Stampelos, and I. N. Alexopoulou, Tetrahedron, 1997, 53, 707 and references cited therein.
52. For recent accounts see: P. Merino, S. Franco, F. L. Merchan, and T. Tejero, Synlett, 2000, in press (Manuscript A-241/06/99).
53. (b) P. Merino and T. Tejero, Molecules, 1999, 4, 165.
54. (c) P. Merino, S. Franco, F. L. Merchan, and T. Tejero, in "Recent Research Developments in Synthetic Organic Chemistry", Vol. 1, ed. by S. G. Pandalai, Transworld Research Network, Trivandum, India, 1998, p. 109.
55. Nucleophilic additions: F. L. Merchan, P. Merino, I. Rojo, T. Tejero, and A. Dondoni, Tetrahedron: Asymmetry, 1996, 7, 667. Cycloaddition reactions: T. Tejero, A. Dondoni, F. L. Merchan, P. Merino, and I. Rojo, Tetrahedron, 1997, 53, 3301. For a comprehensive review of the synthetic utility of thiazole see: A. Dondoni and P. Merino, Thiazoles In "Comprehensive Heterocyclic Chemistry", 2nd edition, ed. by A. R. Katritzky, C. W. Rees, and E. F. V. Scriven, Elsevier, 1996, Vol. 3, Chapter 6, pp. 373.
56. Nucleophilic additions: F. L. Merchan, P. Merino, I. Rojo, T. Tejero, and A. Dondoni, Tetrahedron: Asymmetry, 1996, 7, 667. Cycloaddition reactions: T. Tejero, A. Dondoni, F. L. Merchan, P. Merino, and I. Rojo, Tetrahedron, 1997, 53, 3301. For a comprehensive review of the synthetic utility of thiazole see: A. Dondoni and P. Merino, Thiazoles In "Comprehensive Heterocyclic Chemistry", 2nd edition, ed. by A. R. Katritzky, C. W. Rees, and E. F. V. Scriven, Elsevier, 1996, Vol. 3, Chapter 6, pp. 373.
57. Nucleophilic additions: F. L. Merchan, P. Merino, I. Rojo, T. Tejero, and A. Dondoni, Tetrahedron: Asymmetry, 1996, 7, 667. Cycloaddition reactions: T. Tejero, A. Dondoni, F. L. Merchan, P. Merino, and I. Rojo, Tetrahedron, 1997, 53, 3301. For a comprehensive review of the synthetic utility of thiazole see: A. Dondoni and P. Merino, Thiazoles In "Comprehensive Heterocyclic Chemistry", 2nd edition, ed. by A. R. Katritzky, C. W. Rees, and E. F. V. Scriven, Elsevier, 1996, Vol. 3, Chapter 6, pp. 373.
58. For previous reports concerning hetaryl nitrones see: C. Camiletti, L. Poletti, and C. Trombini, J. Org. Chem., 1994, 59, 6843; J. C. Rohlof, T. V. Alfredson, and M. A. Schwartz, Tetrahedron Lett., 1994, 35, 1011; A. Basha, R. Henry, M. A. Mclaughlin, J. D. Ratajczyck, and S. J. Wittenberger, J. Org. Chem., 1994, 59, 6103; see also ref. 11.
59. For previous reports concerning hetaryl nitrones see: C. Camiletti, L. Poletti, and C. Trombini, J. Org. Chem., 1994, 59, 6843; J. C. Rohlof, T. V. Alfredson, and M. A. Schwartz, Tetrahedron Lett., 1994, 35, 1011; A. Basha, R. Henry, M. A. Mclaughlin, J. D. Ratajczyck, and S. J. Wittenberger, J. Org. Chem., 1994, 59, 6103; see also ref. 11.
60. For previous reports concerning hetaryl nitrones see: C. Camiletti, L. Poletti, and C. Trombini, J. Org. Chem., 1994, 59, 6843; J. C. Rohlof, T. V. Alfredson, and M. A. Schwartz, Tetrahedron Lett., 1994, 35, 1011; A. Basha, R. Henry, M. A. Mclaughlin, J. D. Ratajczyck, and S. J. Wittenberger, J. Org. Chem., 1994, 59, 6103; see also ref. 11.
61. A. Dondoni, S. Franco, F. Junquera, F. Merchan, P. Merino, and T. Tejero, Synth. Commun., 1994, 24, 2537.
62. H. G. Aurich, M. Franzke, and H. P. Kesselheim, Tetrahedron, 1992, 48, 663.
63. 2Ph) resonances.
64. K. N. Houk, J. Sims, C. R. Watts, and L. Luskus, J. Am. Chem. Soc., 1973, 95, 7301; I. Fleming, Frontier Orbitals and Organic Chemical Reactions, John Wiley & sons, New York, 1976, p. 32.
65. K. N. Houk, J. Sims, C. R. Watts, and L. Luskus, J. Am. Chem. Soc., 1973, 95, 7301; I. Fleming, Frontier Orbitals and Organic Chemical Reactions, John Wiley & sons, New York, 1976, p. 32.
66. HOMO-LUMO calculations (PM3, MOPAC97) were performed using the WinMOPAC 2.0 package. Fujistsu Ltd. Japan. 1998.
67. Semiempirical calculations were were performed using the WinMOPAC 2.0 package. Fujistsu Ltd., Japan, 1998. For the ab initio calculations Gaussian98 was used (Gaussian 98, Revision A.3, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, V. G. Zakrzewski, J. A. Montgomery, Jr., R. E. Stratmann, J. C. Burant, S. Dapprich, J. M. Millam, A. D. Daniels, K. N. Kudin, M. C. Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi, R. Cammi, B. Mennucci, C. Pomelli, C. Adamo, S. Clifford, J. Ochterski, G. A. Petersson, P. Y. Ayala, Q. Cui, K. Morokuma, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. Cioslowski, J. V. Ortiz, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. Gomperts, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara, C. Gonzalez, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W. Wong, J. L. Andres, C. Gonzalez, M. Head-Gordon, E. S. Replogle, and J. A. Pople, Gaussian, Inc., Pittsburgh PA, 1998.)
68. In all calculations, Bn was replaced with Me
69. R. Annunziata, M. Benaglia, M. Cinquini, F. Cozzi, and L. Raimondi, J. Org. Chem., 1995, 60, 4697.
70. Y. L. Pascal, J. Chanet-Ray, R. Vessiere, and A. Zeroual, Tetrahedron, 1992, 48, 7197; R. Sustmann, W. Sicking, and R. Huisgen, J. Am. Chem. Soc., 1995, 117, 9679.
71. Y. L. Pascal, J. Chanet-Ray, R. Vessiere, and A. Zeroual, Tetrahedron, 1992, 48, 7197; R. Sustmann, W. Sicking, and R. Huisgen, J. Am. Chem. Soc., 1995, 117, 9679.
72. (a) H. K. Desai, B. S. Joshi, A. M. Panu, and S. W. Pelletier, J. Chromatography, 1985, 322, 223.
73. (b) K. Hostettmann, M. Hostettmann-Kaldas, and O. Sticher, J. Chromatography, 1980, 202, 154.
74. (c) M. Ferrari and L. Verotta, J. Chromatography, 1988, 437, 328.