A convenient new route to piperidines, pyrrolizidines, indolizidines, and quinolizidines by cyclization of acetylenic sulfones with β- and γ-chloroamines. Enantioselective total synthesis of indolizidines (-)-167B, (-)-209D, (-)-209B, and (-)-207A

Journal of Organic Chemistry

Volumn 65, Issue 15, 2000, Pages 4543-4552

  Back, Thomas G ^a   Nakajima, Katsumasa ^a  

^a UNIVERSITY OF CALGARY   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

ALKALOID; ALKYNE; AMINE; AMINO ACID; BENZYLAMINE DERIVATIVE; CHLORINE DERIVATIVE; COPPER DERIVATIVE; INDOLIZIDINE DERIVATIVE; METHIONINE; PHENYLALANINE; PIPERIDINE DERIVATIVE; PYRROLE DERIVATIVE; PYRROLIZIDINE DERIVATIVE; QUINOLIZIDINE DERIVATIVE; SODIUM DERIVATIVE; SULFONE DERIVATIVE; TRIFLUOROACETIC ACID;

ACYLATION; ALKYLATION; ARTICLE; CHIRALITY; CHLORINATION; CONJUGATION; CYCLIZATION; ENANTIOMER; PROTON TRANSPORT; REACTION ANALYSIS; REDUCTION; STEREOCHEMISTRY; SYNTHESIS;

ACYLATION; ALKALOIDS; ALKYLATION; ANIMALS; ANIMALS, POISONOUS; ANURA; CYCLIZATION; INDOLIZINES; PIPERIDINES; PYRROLIDINES; QUINOLIZINES; STEREOISOMERISM; TOXINS, BIOLOGICAL;

EID: 0034725907     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo000080p     Document Type: Article

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2. (b) Tanaka, K.; Kaji, A. In The Chemistry of Sulphones and Sulphoxides; Patai, S.; Rappoport, Z.; Stirling, C. J. M., Eds.; Wiley: Chichester, 1988; Chapter 15.
3. For reviews, see: (a) ref 1a, Chapter 6. (b) De Lucchi, O.; Pasquato, L. Tetrahedron 1988, 44, 6755. For lead references, see: (c) Back, T. G.; Bethell, R. J.; Parvez, M.; Taylor, J. A.; Wehrli, D. J. Org. Chem. 1999, 64, 7426. (d) Shen, M.; Schultz, A. G. Tetrahedron Lett. 1981, 22, 3347.
4. For reviews, see: (a) ref 1a, Chapter 6. (b) De Lucchi, O.; Pasquato, L. Tetrahedron 1988, 44, 6755. For lead references, see: (c) Back, T. G.; Bethell, R. J.; Parvez, M.; Taylor, J. A.; Wehrli, D. J. Org. Chem. 1999, 64, 7426. (d) Shen, M.; Schultz, A. G. Tetrahedron Lett. 1981, 22, 3347.
5. For reviews, see: (a) ref 1a, Chapter 6. (b) De Lucchi, O.; Pasquato, L. Tetrahedron 1988, 44, 6755. For lead references, see: (c) Back, T. G.; Bethell, R. J.; Parvez, M.; Taylor, J. A.; Wehrli, D. J. Org. Chem. 1999, 64, 7426. (d) Shen, M.; Schultz, A. G. Tetrahedron Lett. 1981, 22, 3347.
6. For reviews, see: (a) ref 1a, Chapter 6. (b) De Lucchi, O.; Pasquato, L. Tetrahedron 1988, 44, 6755. For lead references, see: (c) Back, T. G.; Bethell, R. J.; Parvez, M.; Taylor, J. A.; Wehrli, D. J. Org. Chem. 1999, 64, 7426. (d) Shen, M.; Schultz, A. G. Tetrahedron Lett. 1981, 22, 3347.
7. For reviews of sulfone-stabilized carbanions, see: (a) ref 1a, Chapter 3. (b) Block, E. Reactions of Organosulfur Compounds; Academic Press: New York, 1978; Chapter 2. (c) Nájera, C.; Sansano, J. M. Recent Res. Dev. Org. Chem. 1998, 2, 637. For examples of sulfone-stabilized vinyl carbanions, see: (d) Eisch, J. J.; Galle, J. E. J. Org. Chem. 1979, 44, 3279. (e) Kleijn, H.; Vermeer, P. J. Organomet. Chem. 1986, 302, 1. (f) Nájera, C.; Yus, M. J. Org. Chem. 1988, 53, 4708. (g) Pelter, A.; Ward, R. S.; Little, G. M. J. Chem. Soc., Perkin Trans. 1 1990, 2775. (h) Caturla, F.; Nájera, C. Tetrahedron 1997, 53, 11449.
8. For reviews of sulfone-stabilized carbanions, see: (a) ref 1a, Chapter 3. (b) Block, E. Reactions of Organosulfur Compounds; Academic Press: New York, 1978; Chapter 2. (c) Nájera, C.; Sansano, J. M. Recent Res. Dev. Org. Chem. 1998, 2, 637. For examples of sulfone-stabilized vinyl carbanions, see: (d) Eisch, J. J.; Galle, J. E. J. Org. Chem. 1979, 44, 3279. (e) Kleijn, H.; Vermeer, P. J. Organomet. Chem. 1986, 302, 1. (f) Nájera, C.; Yus, M. J. Org. Chem. 1988, 53, 4708. (g) Pelter, A.; Ward, R. S.; Little, G. M. J. Chem. Soc., Perkin Trans. 1 1990, 2775. (h) Caturla, F.; Nájera, C. Tetrahedron 1997, 53, 11449.
9. For reviews of sulfone-stabilized carbanions, see: (a) ref 1a, Chapter 3. (b) Block, E. Reactions of Organosulfur Compounds; Academic Press: New York, 1978; Chapter 2. (c) Nájera, C.; Sansano, J. M. Recent Res. Dev. Org. Chem. 1998, 2, 637. For examples of sulfone-stabilized vinyl carbanions, see: (d) Eisch, J. J.; Galle, J. E. J. Org. Chem. 1979, 44, 3279. (e) Kleijn, H.; Vermeer, P. J. Organomet. Chem. 1986, 302, 1. (f) Nájera, C.; Yus, M. J. Org. Chem. 1988, 53, 4708. (g) Pelter, A.; Ward, R. S.; Little, G. M. J. Chem. Soc., Perkin Trans. 1 1990, 2775. (h) Caturla, F.; Nájera, C. Tetrahedron 1997, 53, 11449.
10. For reviews of sulfone-stabilized carbanions, see: (a) ref 1a, Chapter 3. (b) Block, E. Reactions of Organosulfur Compounds; Academic Press: New York, 1978; Chapter 2. (c) Nájera, C.; Sansano, J. M. Recent Res. Dev. Org. Chem. 1998, 2, 637. For examples of sulfone-stabilized vinyl carbanions, see: (d) Eisch, J. J.; Galle, J. E. J. Org. Chem. 1979, 44, 3279. (e) Kleijn, H.; Vermeer, P. J. Organomet. Chem. 1986, 302, 1. (f) Nájera, C.; Yus, M. J. Org. Chem. 1988, 53, 4708. (g) Pelter, A.; Ward, R. S.; Little, G. M. J. Chem. Soc., Perkin Trans. 1 1990, 2775. (h) Caturla, F.; Nájera, C. Tetrahedron 1997, 53, 11449.
11. For reviews of sulfone-stabilized carbanions, see: (a) ref 1a, Chapter 3. (b) Block, E. Reactions of Organosulfur Compounds; Academic Press: New York, 1978; Chapter 2. (c) Nájera, C.; Sansano, J. M. Recent Res. Dev. Org. Chem. 1998, 2, 637. For examples of sulfone-stabilized vinyl carbanions, see: (d) Eisch, J. J.; Galle, J. E. J. Org. Chem. 1979, 44, 3279. (e) Kleijn, H.; Vermeer, P. J. Organomet. Chem. 1986, 302, 1. (f) Nájera, C.; Yus, M. J. Org. Chem. 1988, 53, 4708. (g) Pelter, A.; Ward, R. S.; Little, G. M. J. Chem. Soc., Perkin Trans. 1 1990, 2775. (h) Caturla, F.; Nájera, C. Tetrahedron 1997, 53, 11449.
12. For reviews of sulfone-stabilized carbanions, see: (a) ref 1a, Chapter 3. (b) Block, E. Reactions of Organosulfur Compounds; Academic Press: New York, 1978; Chapter 2. (c) Nájera, C.; Sansano, J. M. Recent Res. Dev. Org. Chem. 1998, 2, 637. For examples of sulfone-stabilized vinyl carbanions, see: (d) Eisch, J. J.; Galle, J. E. J. Org. Chem. 1979, 44, 3279. (e) Kleijn, H.; Vermeer, P. J. Organomet. Chem. 1986, 302, 1. (f) Nájera, C.; Yus, M. J. Org. Chem. 1988, 53, 4708. (g) Pelter, A.; Ward, R. S.; Little, G. M. J. Chem. Soc., Perkin Trans. 1 1990, 2775. (h) Caturla, F.; Nájera, C. Tetrahedron 1997, 53, 11449.
13. For reviews of sulfone-stabilized carbanions, see: (a) ref 1a, Chapter 3. (b) Block, E. Reactions of Organosulfur Compounds; Academic Press: New York, 1978; Chapter 2. (c) Nájera, C.; Sansano, J. M. Recent Res. Dev. Org. Chem. 1998, 2, 637. For examples of sulfone-stabilized vinyl carbanions, see: (d) Eisch, J. J.; Galle, J. E. J. Org. Chem. 1979, 44, 3279. (e) Kleijn, H.; Vermeer, P. J. Organomet. Chem. 1986, 302, 1. (f) Nájera, C.; Yus, M. J. Org. Chem. 1988, 53, 4708. (g) Pelter, A.; Ward, R. S.; Little, G. M. J. Chem. Soc., Perkin Trans. 1 1990, 2775. (h) Caturla, F.; Nájera, C. Tetrahedron 1997, 53, 11449.
14. For reviews of sulfone-stabilized carbanions, see: (a) ref 1a, Chapter 3. (b) Block, E. Reactions of Organosulfur Compounds; Academic Press: New York, 1978; Chapter 2. (c) Nájera, C.; Sansano, J. M. Recent Res. Dev. Org. Chem. 1998, 2, 637. For examples of sulfone-stabilized vinyl carbanions, see: (d) Eisch, J. J.; Galle, J. E. J. Org. Chem. 1979, 44, 3279. (e) Kleijn, H.; Vermeer, P. J. Organomet. Chem. 1986, 302, 1. (f) Nájera, C.; Yus, M. J. Org. Chem. 1988, 53, 4708. (g) Pelter, A.; Ward, R. S.; Little, G. M. J. Chem. Soc., Perkin Trans. 1 1990, 2775. (h) Caturla, F.; Nájera, C. Tetrahedron 1997, 53, 11449.
15. (a) See ref 1a, Chapter 9.
16. (b) Nájera, C.; Yus, M. Tetrahedron 1999, 55, 10547.
17. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
18. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
19. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
20. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
21. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
22. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
23. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
24. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
25. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
26. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
27. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
28. For illustrative examples, see: (a) Ghera, E.; Maurya, R.; BenDavid, Y. J. Org. Chem. 1988, 53, 1912. (b) Grimm, E. L.; Levac, S.; Coutu, M. L. Tetrahedron Lett. 1994, 35, 5369. (c) Grimm, E. L.; Coutu, M. L.; Trimble, L. A. Tetrahedron Lett. 1993, 34, 7017. (d) Gamble, M. P.; Giblin, G. M. P.; Taylor, R. J. K. Synlett 1995, 779. (e) Magnus, P.; Booth, J.; Magnus, N.; Tarrant, J.; Thom, S.; Ujjainwalla, F. Tetrahedron Lett. 1995, 36, 5331. (f) McCombie, S. W.; Shankar, B. B.; Ganguly, A. K. Tetrahedron Lett. 1987, 28, 4123. (g) Date, M.; Watanabe, M.; Furukawa, S. Chem. Pharm. Bull. 1990, 38, 902. (h) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1995, 60, 6000. (i) Carretero, J. C.; Arrayás, R. G. J. Org. Chem. 1998, 63, 2993. (j) Carretero, J. C.; Arrayás, R. G.; Storch de Garcia, I. Tetrahedron Lett. 1997, 38, 8537. (k) Carretero, J. C.; Arrayás, R. G. Synlett 1999, 49. (l) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997, 53, 7139.
29. Back, T. G.; Nakajima, K. J. Org. Chem. 1998, 63, 6566.
30. Preliminary communication: Back, T. G.; Nakajima, K. Org. Lett. 1999, 1, 261.
31. For general reviews of dendrobatid alkaloids, see: (a) Daly, J. W.; Spande, T. F. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1986; Vol. 4, Chapter 1. (b) Witkop, B.; Gössinger, E. In The Alkaloids: Chemistry and Pharmacology; Brossi, A., Ed.; Academic Science, New York, 1983; Vol. 21, Chapter 5. (c) Daly, J. W.; Brown, G. B.; Mensah-Dwumah, M.; Myers, C. W. Toxicon 1978, 16, 163. (d) Mensah-Dwumah, M.; Daly, J. W. Toxicon 1978, 16, 189. (e) Daly, J. W.; Myers, C. W. Whittaker, N. Toxicon 1987, 25, 1023.
32. For general reviews of dendrobatid alkaloids, see: (a) Daly, J. W.; Spande, T. F. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1986; Vol. 4, Chapter 1. (b) Witkop, B.; Gössinger, E. In The Alkaloids: Chemistry and Pharmacology; Brossi, A., Ed.; Academic Science, New York, 1983; Vol. 21, Chapter 5. (c) Daly, J. W.; Brown, G. B.; Mensah-Dwumah, M.; Myers, C. W. Toxicon 1978, 16, 163. (d) Mensah-Dwumah, M.; Daly, J. W. Toxicon 1978, 16, 189. (e) Daly, J. W.; Myers, C. W. Whittaker, N. Toxicon 1987, 25, 1023.
33. For general reviews of dendrobatid alkaloids, see: (a) Daly, J. W.; Spande, T. F. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1986; Vol. 4, Chapter 1. (b) Witkop, B.; Gössinger, E. In The Alkaloids: Chemistry and Pharmacology; Brossi, A., Ed.; Academic Science, New York, 1983; Vol. 21, Chapter 5. (c) Daly, J. W.; Brown, G. B.; Mensah-Dwumah, M.; Myers, C. W. Toxicon 1978, 16, 163. (d) Mensah-Dwumah, M.; Daly, J. W. Toxicon 1978, 16, 189. (e) Daly, J. W.; Myers, C. W. Whittaker, N. Toxicon 1987, 25, 1023.
34. For general reviews of dendrobatid alkaloids, see: (a) Daly, J. W.; Spande, T. F. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1986; Vol. 4, Chapter 1. (b) Witkop, B.; Gössinger, E. In The Alkaloids: Chemistry and Pharmacology; Brossi, A., Ed.; Academic Science, New York, 1983; Vol. 21, Chapter 5. (c) Daly, J. W.; Brown, G. B.; Mensah-Dwumah, M.; Myers, C. W. Toxicon 1978, 16, 163. (d) Mensah-Dwumah, M.; Daly, J. W. Toxicon 1978, 16, 189. (e) Daly, J. W.; Myers, C. W. Whittaker, N. Toxicon 1987, 25, 1023.
35. For general reviews of dendrobatid alkaloids, see: (a) Daly, J. W.; Spande, T. F. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1986; Vol. 4, Chapter 1. (b) Witkop, B.; Gössinger, E. In The Alkaloids: Chemistry and Pharmacology; Brossi, A., Ed.; Academic Science, New York, 1983; Vol. 21, Chapter 5. (c) Daly, J. W.; Brown, G. B.; Mensah-Dwumah, M.; Myers, C. W. Toxicon 1978, 16, 163. (d) Mensah-Dwumah, M.; Daly, J. W. Toxicon 1978, 16, 189. (e) Daly, J. W.; Myers, C. W. Whittaker, N. Toxicon 1987, 25, 1023.
36. (a) Nakajima, K. Ph.D. Thesis, University of Calgary, 2000.
37. a values of sulfones compared to esters.
38. Dolfini, J. E.; Dolfini, D. M. Tetrahedron Lett. 1964, 2103.
39. Piper, J. R.; Johnston, T. P. J. Org. Chem. 1963, 28, 981.
40. Norton, T. R.; Seibert, R. A.; Benson, A. A.; Bergstrom, F. W. J. Am. Chem. Soc. 1946, 68, 1572.
41. For lead references, see March, J. In Advanced Organic Chemistry, 4th ed.; Wiley: New York, 1992; pp 1083-1085.
42. For the Arndt-Eistert homologation of (L)-proline, see: (a) Cassal, J.-M.; Fürst, A.; Meier, W. Helv. Chim. Acta 1976, 59, 1917. The preparation of racemic 8d has also been reported; see: (b) Sandoz Ltd., Neth. Appl. Patent 6,600,184; July, 13, 1966 via Chem. Abstr. 1967, 66, 2580r. (c) Mahesh, V. K.; Sharma, R.; Maheshwari, M. Indian J. Chem, Sect. B 1984, 23, 486.
43. For the Arndt-Eistert homologation of (L)-proline, see: (a) Cassal, J.-M.; Fürst, A.; Meier, W. Helv. Chim. Acta 1976, 59, 1917. The preparation of racemic 8d has also been reported; see: (b) Sandoz Ltd., Neth. Appl. Patent 6,600,184; July, 13, 1966 via Chem. Abstr. 1967, 66, 2580r. (c) Mahesh, V. K.; Sharma, R.; Maheshwari, M. Indian J. Chem, Sect. B 1984, 23, 486.
44. For the Arndt-Eistert homologation of (L)-proline, see: (a) Cassal, J.-M.; Fürst, A.; Meier, W. Helv. Chim. Acta 1976, 59, 1917. The preparation of racemic 8d has also been reported; see: (b) Sandoz Ltd., Neth. Appl. Patent 6,600,184; July, 13, 1966 via Chem. Abstr. 1967, 66, 2580r. (c) Mahesh, V. K.; Sharma, R.; Maheshwari, M. Indian J. Chem, Sect. B 1984, 23, 486.
45. Drey, C. N. C.; Mtetwa, E. J. Chem. Soc., Perkin Trans. 1 1982, 1587.
46. Bardou, A.; Célérier, J.-P.; Lhommet, G. Tetrahedron Lett. 1998, 39, 5189.
47. Chen, Z.; Trudell, M. L. Synth. Commun. 1994, 24, 3149.
48. For the preparation of acetylenic sulfones by selenosulfonation, see: (a) Back, T. G. In Organoselenium Chemistry - A Practical Approach; Back, T. G., Ed.; Oxford University Press: Oxford, 1999; Chapter 9. (b) Back, T. G.; Collins, S.; Kerr, R. G. J. Org. Chem. 1983, 48, 3077. (c) Miura, T.; Kobayashi, M. J. Chem. Soc., Chem. Commun. 1982, 438.
49. For the preparation of acetylenic sulfones by selenosulfonation, see: (a) Back, T. G. In Organoselenium Chemistry - A Practical Approach; Back, T. G., Ed.; Oxford University Press: Oxford, 1999; Chapter 9. (b) Back, T. G.; Collins, S.; Kerr, R. G. J. Org. Chem. 1983, 48, 3077. (c) Miura, T.; Kobayashi, M. J. Chem. Soc., Chem. Commun. 1982, 438.
50. For the preparation of acetylenic sulfones by selenosulfonation, see: (a) Back, T. G. In Organoselenium Chemistry - A Practical Approach; Back, T. G., Ed.; Oxford University Press: Oxford, 1999; Chapter 9. (b) Back, T. G.; Collins, S.; Kerr, R. G. J. Org. Chem. 1983, 48, 3077. (c) Miura, T.; Kobayashi, M. J. Chem. Soc., Chem. Commun. 1982, 438.
51. Back, T. G.; Lai, E. K. Y.; Muralidharan, K. R. J. Org. Chem. 1990, 55, 4595.
52. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
53. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
54. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
55. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
56. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
57. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
58. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
59. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
60. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
61. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
62. For examples of conjugate additions of amines to acetylenic sulfones, see: (a) Truce, W. E.; Brady, D. G. J. Org. Chem. 1966, 31, 3543. (b) Truce, W. E.; Markley, L. D. J. Org. Chem. 1970, 35, 3275. (c) Truce, W. E.; Onken, D. W. J. Org. Chem. 1975, 40, 3200. (d) Stirling, C. J. M. J. Chem. Soc. 1964, 5863. (e) Pink, R. C.; Spratt, R.; Stirling, C. J. M. J. Chem. Soc. 1965, 5714. (f) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. B 1966, 1217. (g) McDowell, S. T.; Stirling, C. J. M. J. Chem. Soc. B 1967, 351. (h) Cossu, S.; De Lucchi, O.; Durr, R. Synth. Commun. 1996, 26, 4597. (i) Cinquini, M.; Cozzi, F.; Pelosi, M. J. Chem. Soc., Perkin Trans. 1 1979, 1430. (j) Back, T. G.; Collins, S.; Law, K.-W. Can. J. Chem. 1985, 63, 2313. (k) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. J. Org. Chem. 1998, 63, 7908.
63. For lead references, see: piperidine alkaloids: (a) Strunz, G. M.; Findlay, J. A. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 89-183. (b) Fodor, G. B.; Colasanti, B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 1-90. Indolizidine and quinolizidine alkaloids: (c) Howard, A. S.; Michael, J. P. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1986; Vol. 28, pp 183-308. (d) Herbert, R. B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 241-274. Pyrrolizidine alkaloids: (e) Wróbel, J. T. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 327-384. For a list of other reviews of these classes of alkaloids, see: (f) Dewick, P. M. Medicinal Natural Products; Wiley: Chichester, 1997; pp 371-374.
64. For lead references, see: piperidine alkaloids: (a) Strunz, G. M.; Findlay, J. A. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 89-183. (b) Fodor, G. B.; Colasanti, B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 1-90. Indolizidine and quinolizidine alkaloids: (c) Howard, A. S.; Michael, J. P. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1986; Vol. 28, pp 183-308. (d) Herbert, R. B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 241-274. Pyrrolizidine alkaloids: (e) Wróbel, J. T. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 327-384. For a list of other reviews of these classes of alkaloids, see: (f) Dewick, P. M. Medicinal Natural Products; Wiley: Chichester, 1997; pp 371-374.
65. For lead references, see: piperidine alkaloids: (a) Strunz, G. M.; Findlay, J. A. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 89-183. (b) Fodor, G. B.; Colasanti, B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 1-90. Indolizidine and quinolizidine alkaloids: (c) Howard, A. S.; Michael, J. P. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1986; Vol. 28, pp 183-308. (d) Herbert, R. B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 241-274. Pyrrolizidine alkaloids: (e) Wróbel, J. T. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 327-384. For a list of other reviews of these classes of alkaloids, see: (f) Dewick, P. M. Medicinal Natural Products; Wiley: Chichester, 1997; pp 371-374.
66. For lead references, see: piperidine alkaloids: (a) Strunz, G. M.; Findlay, J. A. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 89-183. (b) Fodor, G. B.; Colasanti, B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 1-90. Indolizidine and quinolizidine alkaloids: (c) Howard, A. S.; Michael, J. P. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1986; Vol. 28, pp 183-308. (d) Herbert, R. B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 241-274. Pyrrolizidine alkaloids: (e) Wróbel, J. T. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 327-384. For a list of other reviews of these classes of alkaloids, see: (f) Dewick, P. M. Medicinal Natural Products; Wiley: Chichester, 1997; pp 371-374.
67. For lead references, see: piperidine alkaloids: (a) Strunz, G. M.; Findlay, J. A. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 89-183. (b) Fodor, G. B.; Colasanti, B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 1-90. Indolizidine and quinolizidine alkaloids: (c) Howard, A. S.; Michael, J. P. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1986; Vol. 28, pp 183-308. (d) Herbert, R. B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 241-274. Pyrrolizidine alkaloids: (e) Wróbel, J. T. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 327-384. For a list of other reviews of these classes of alkaloids, see: (f) Dewick, P. M. Medicinal Natural Products; Wiley: Chichester, 1997; pp 371-374.
68. For lead references, see: piperidine alkaloids: (a) Strunz, G. M.; Findlay, J. A. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 89-183. (b) Fodor, G. B.; Colasanti, B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 1-90. Indolizidine and quinolizidine alkaloids: (c) Howard, A. S.; Michael, J. P. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1986; Vol. 28, pp 183-308. (d) Herbert, R. B. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 3, pp 241-274. Pyrrolizidine alkaloids: (e) Wróbel, J. T. In The Alkaloids; Brossi, A., Ed.; Academic Press: Orlando, 1985; Vol. 26, pp 327-384. For a list of other reviews of these classes of alkaloids, see: (f) Dewick, P. M. Medicinal Natural Products; Wiley: Chichester, 1997; pp 371-374.
69. 3CN-TFA, see: Comins, D. L.; Weglarz, M. A. J. Org. Chem. 1991, 56, 2506.
70. The generally high stereoselectivity of hydride reductions of similar bicyclic iminium ions has been rationalized on the basis of conformational and stereoelectronic effects: Stevens, R. V. Acc. Chem. Res. 1984, 17, 289.
71. 3, see: Marshall, J. A.; Cleary, D. G. J. Org. Chem. 1986, 51, 858.
72. For previous syntheses of (-)-indolizidine 167B (31), see: (a) Weymann, M.; Pfrengle, W.; Schollmeyer, D.; Kunz, H. Synthesis 1997, 1151. (b) Angle, S. R.; Henry, R. M. J. Org. Chem. 1997, 62, 8549. (c) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445. (d) Fleurant, A.; Célérier, J. P.; Lhommet, G. Tetrahedron Asymmetry 1992, 3, 695. (e) Fleurant, A.; Saliou, C.; Célérier, J. P.; Platzer, N.; Moc, T. V.; Lhommet, G. J. Heterocycl. Chem. 1995, 32, 255. (f) Jefford, C. W.; Wang, J. B. Tetrahedron Lett. 1993, 34, 3119. (g) Jefford, C. W.; Tang, Q.; Zaslona, A. J. Am. Chem. Soc. 1991, 113, 3513. (h) Polniaszek, R. P.; Belmont, S. E. J. Org. Chem. 1990, 55, 4688.
73. For previous syntheses of (-)-indolizidine 167B (31), see: (a) Weymann, M.; Pfrengle, W.; Schollmeyer, D.; Kunz, H. Synthesis 1997, 1151. (b) Angle, S. R.; Henry, R. M. J. Org. Chem. 1997, 62, 8549. (c) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445. (d) Fleurant, A.; Célérier, J. P.; Lhommet, G. Tetrahedron Asymmetry 1992, 3, 695. (e) Fleurant, A.; Saliou, C.; Célérier, J. P.; Platzer, N.; Moc, T. V.; Lhommet, G. J. Heterocycl. Chem. 1995, 32, 255. (f) Jefford, C. W.; Wang, J. B. Tetrahedron Lett. 1993, 34, 3119. (g) Jefford, C. W.; Tang, Q.; Zaslona, A. J. Am. Chem. Soc. 1991, 113, 3513. (h) Polniaszek, R. P.; Belmont, S. E. J. Org. Chem. 1990, 55, 4688.
74. For previous syntheses of (-)-indolizidine 167B (31), see: (a) Weymann, M.; Pfrengle, W.; Schollmeyer, D.; Kunz, H. Synthesis 1997, 1151. (b) Angle, S. R.; Henry, R. M. J. Org. Chem. 1997, 62, 8549. (c) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445. (d) Fleurant, A.; Célérier, J. P.; Lhommet, G. Tetrahedron Asymmetry 1992, 3, 695. (e) Fleurant, A.; Saliou, C.; Célérier, J. P.; Platzer, N.; Moc, T. V.; Lhommet, G. J. Heterocycl. Chem. 1995, 32, 255. (f) Jefford, C. W.; Wang, J. B. Tetrahedron Lett. 1993, 34, 3119. (g) Jefford, C. W.; Tang, Q.; Zaslona, A. J. Am. Chem. Soc. 1991, 113, 3513. (h) Polniaszek, R. P.; Belmont, S. E. J. Org. Chem. 1990, 55, 4688.
75. For previous syntheses of (-)-indolizidine 167B (31), see: (a) Weymann, M.; Pfrengle, W.; Schollmeyer, D.; Kunz, H. Synthesis 1997, 1151. (b) Angle, S. R.; Henry, R. M. J. Org. Chem. 1997, 62, 8549. (c) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445. (d) Fleurant, A.; Célérier, J. P.; Lhommet, G. Tetrahedron Asymmetry 1992, 3, 695. (e) Fleurant, A.; Saliou, C.; Célérier, J. P.; Platzer, N.; Moc, T. V.; Lhommet, G. J. Heterocycl. Chem. 1995, 32, 255. (f) Jefford, C. W.; Wang, J. B. Tetrahedron Lett. 1993, 34, 3119. (g) Jefford, C. W.; Tang, Q.; Zaslona, A. J. Am. Chem. Soc. 1991, 113, 3513. (h) Polniaszek, R. P.; Belmont, S. E. J. Org. Chem. 1990, 55, 4688.
76. For previous syntheses of (-)-indolizidine 167B (31), see: (a) Weymann, M.; Pfrengle, W.; Schollmeyer, D.; Kunz, H. Synthesis 1997, 1151. (b) Angle, S. R.; Henry, R. M. J. Org. Chem. 1997, 62, 8549. (c) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445. (d) Fleurant, A.; Célérier, J. P.; Lhommet, G. Tetrahedron Asymmetry 1992, 3, 695. (e) Fleurant, A.; Saliou, C.; Célérier, J. P.; Platzer, N.; Moc, T. V.; Lhommet, G. J. Heterocycl. Chem. 1995, 32, 255. (f) Jefford, C. W.; Wang, J. B. Tetrahedron Lett. 1993, 34, 3119. (g) Jefford, C. W.; Tang, Q.; Zaslona, A. J. Am. Chem. Soc. 1991, 113, 3513. (h) Polniaszek, R. P.; Belmont, S. E. J. Org. Chem. 1990, 55, 4688.
77. For previous syntheses of (-)-indolizidine 167B (31), see: (a) Weymann, M.; Pfrengle, W.; Schollmeyer, D.; Kunz, H. Synthesis 1997, 1151. (b) Angle, S. R.; Henry, R. M. J. Org. Chem. 1997, 62, 8549. (c) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445. (d) Fleurant, A.; Célérier, J. P.; Lhommet, G. Tetrahedron Asymmetry 1992, 3, 695. (e) Fleurant, A.; Saliou, C.; Célérier, J. P.; Platzer, N.; Moc, T. V.; Lhommet, G. J. Heterocycl. Chem. 1995, 32, 255. (f) Jefford, C. W.; Wang, J. B. Tetrahedron Lett. 1993, 34, 3119. (g) Jefford, C. W.; Tang, Q.; Zaslona, A. J. Am. Chem. Soc. 1991, 113, 3513. (h) Polniaszek, R. P.; Belmont, S. E. J. Org. Chem. 1990, 55, 4688.
78. For previous syntheses of (-)-indolizidine 167B (31), see: (a) Weymann, M.; Pfrengle, W.; Schollmeyer, D.; Kunz, H. Synthesis 1997, 1151. (b) Angle, S. R.; Henry, R. M. J. Org. Chem. 1997, 62, 8549. (c) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445. (d) Fleurant, A.; Célérier, J. P.; Lhommet, G. Tetrahedron Asymmetry 1992, 3, 695. (e) Fleurant, A.; Saliou, C.; Célérier, J. P.; Platzer, N.; Moc, T. V.; Lhommet, G. J. Heterocycl. Chem. 1995, 32, 255. (f) Jefford, C. W.; Wang, J. B. Tetrahedron Lett. 1993, 34, 3119. (g) Jefford, C. W.; Tang, Q.; Zaslona, A. J. Am. Chem. Soc. 1991, 113, 3513. (h) Polniaszek, R. P.; Belmont, S. E. J. Org. Chem. 1990, 55, 4688.
79. For previous syntheses of (-)-indolizidine 167B (31), see: (a) Weymann, M.; Pfrengle, W.; Schollmeyer, D.; Kunz, H. Synthesis 1997, 1151. (b) Angle, S. R.; Henry, R. M. J. Org. Chem. 1997, 62, 8549. (c) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445. (d) Fleurant, A.; Célérier, J. P.; Lhommet, G. Tetrahedron Asymmetry 1992, 3, 695. (e) Fleurant, A.; Saliou, C.; Célérier, J. P.; Platzer, N.; Moc, T. V.; Lhommet, G. J. Heterocycl. Chem. 1995, 32, 255. (f) Jefford, C. W.; Wang, J. B. Tetrahedron Lett. 1993, 34, 3119. (g) Jefford, C. W.; Tang, Q.; Zaslona, A. J. Am. Chem. Soc. 1991, 113, 3513. (h) Polniaszek, R. P.; Belmont, S. E. J. Org. Chem. 1990, 55, 4688.
80. For previous syntheses of (-)-indolizidine 209D (32), see: refs 25c, 25f, 25h, and (a) Nukui, S.; Sodeoka, M.; Sasai, H.; Shibasaki, M. J. Org. Chem. 1995, 60, 398. (b)Åhman, J.; Somfai, P. Tetrahedron 1995, 51, 9747. (c) Jefford, C. W.; Sienkiewicz, K.; Thornton, S. R. Helv. Chim. Acta 1995, 78, 1511. (d) Takahata, H.; Kubota, M.; Ihara, K.; Okamoto, N.; Momose, T.; Azer, N.; Eldefrawi, A. T.; Eldefrawi, M. E. Tetrahedron: Asymmetry 1998, 9, 3289.
81. For previous syntheses of (-)-indolizidine 209D (32), see: refs 25c, 25f, 25h, and (a) Nukui, S.; Sodeoka, M.; Sasai, H.; Shibasaki, M. J. Org. Chem. 1995, 60, 398. (b)Åhman, J.; Somfai, P. Tetrahedron 1995, 51, 9747. (c) Jefford, C. W.; Sienkiewicz, K.; Thornton, S. R. Helv. Chim. Acta 1995, 78, 1511. (d) Takahata, H.; Kubota, M.; Ihara, K.; Okamoto, N.; Momose, T.; Azer, N.; Eldefrawi, A. T.; Eldefrawi, M. E. Tetrahedron: Asymmetry 1998, 9, 3289.
82. For previous syntheses of (-)-indolizidine 209D (32), see: refs 25c, 25f, 25h, and (a) Nukui, S.; Sodeoka, M.; Sasai, H.; Shibasaki, M. J. Org. Chem. 1995, 60, 398. (b)Åhman, J.; Somfai, P. Tetrahedron 1995, 51, 9747. (c) Jefford, C. W.; Sienkiewicz, K.; Thornton, S. R. Helv. Chim. Acta 1995, 78, 1511. (d) Takahata, H.; Kubota, M.; Ihara, K.; Okamoto, N.; Momose, T.; Azer, N.; Eldefrawi, A. T.; Eldefrawi, M. E. Tetrahedron: Asymmetry 1998, 9, 3289.
83. For previous syntheses of (-)-indolizidine 209D (32), see: refs 25c, 25f, 25h, and (a) Nukui, S.; Sodeoka, M.; Sasai, H.; Shibasaki, M. J. Org. Chem. 1995, 60, 398. (b)Åhman, J.; Somfai, P. Tetrahedron 1995, 51, 9747. (c) Jefford, C. W.; Sienkiewicz, K.; Thornton, S. R. Helv. Chim. Acta 1995, 78, 1511. (d) Takahata, H.; Kubota, M.; Ihara, K.; Okamoto, N.; Momose, T.; Azer, N.; Eldefrawi, A. T.; Eldefrawi, M. E. Tetrahedron: Asymmetry 1998, 9, 3289.
84. For previous syntheses of (-)-indolizidine 209B (33), see: refs 16, 26b, 26c, and (a) Michael, J. P.; Gravestock, D. Pure Appl. Chem. 1997, 69, 583. (b) Aube, J.; Rafferty, P. S.; Milligan, G. L. Heterocycles 1993, 35, 1141. (c) Satake, A.; Shimizu, I. Tetrahedron: Asymmetry 1993, 4, 1405. (d) Shishido, Y.; Kibayashi, C. J. Org. Chem. 1992, 57, 2876. (e) Holmes, A. B.; Smith, A. L.; Williams, S. F.; Hughes, L. R.; Lidert, Z.; Swithenbank, C. J. Org. Chem. 1991, 56, 1393.
85. For previous syntheses of (-)-indolizidine 209B (33), see: refs 16, 26b, 26c, and (a) Michael, J. P.; Gravestock, D. Pure Appl. Chem. 1997, 69, 583. (b) Aube, J.; Rafferty, P. S.; Milligan, G. L. Heterocycles 1993, 35, 1141. (c) Satake, A.; Shimizu, I. Tetrahedron: Asymmetry 1993, 4, 1405. (d) Shishido, Y.; Kibayashi, C. J. Org. Chem. 1992, 57, 2876. (e) Holmes, A. B.; Smith, A. L.; Williams, S. F.; Hughes, L. R.; Lidert, Z.; Swithenbank, C. J. Org. Chem. 1991, 56, 1393.
86. For previous syntheses of (-)-indolizidine 209B (33), see: refs 16, 26b, 26c, and (a) Michael, J. P.; Gravestock, D. Pure Appl. Chem. 1997, 69, 583. (b) Aube, J.; Rafferty, P. S.; Milligan, G. L. Heterocycles 1993, 35, 1141. (c) Satake, A.; Shimizu, I. Tetrahedron: Asymmetry 1993, 4, 1405. (d) Shishido, Y.; Kibayashi, C. J. Org. Chem. 1992, 57, 2876. (e) Holmes, A. B.; Smith, A. L.; Williams, S. F.; Hughes, L. R.; Lidert, Z.; Swithenbank, C. J. Org. Chem. 1991, 56, 1393.
87. For previous syntheses of (-)-indolizidine 209B (33), see: refs 16, 26b, 26c, and (a) Michael, J. P.; Gravestock, D. Pure Appl. Chem. 1997, 69, 583. (b) Aube, J.; Rafferty, P. S.; Milligan, G. L. Heterocycles 1993, 35, 1141. (c) Satake, A.; Shimizu, I. Tetrahedron: Asymmetry 1993, 4, 1405. (d) Shishido, Y.; Kibayashi, C. J. Org. Chem. 1992, 57, 2876. (e) Holmes, A. B.; Smith, A. L.; Williams, S. F.; Hughes, L. R.; Lidert, Z.; Swithenbank, C. J. Org. Chem. 1991, 56, 1393.
88. For previous syntheses of (-)-indolizidine 209B (33), see: refs 16, 26b, 26c, and (a) Michael, J. P.; Gravestock, D. Pure Appl. Chem. 1997, 69, 583. (b) Aube, J.; Rafferty, P. S.; Milligan, G. L. Heterocycles 1993, 35, 1141. (c) Satake, A.; Shimizu, I. Tetrahedron: Asymmetry 1993, 4, 1405. (d) Shishido, Y.; Kibayashi, C. J. Org. Chem. 1992, 57, 2876. (e) Holmes, A. B.; Smith, A. L.; Williams, S. F.; Hughes, L. R.; Lidert, Z.; Swithenbank, C. J. Org. Chem. 1991, 56, 1393.
89. For previous syntheses of (-)-indolizidine 207A (40), see: ref 27d and (a) Comins, D. L.; LaMunyon, D. H.; Chen, X. J. Org. Chem. 1997, 62, 8182. (b) Taber, D. F.; Rahimizadeh, M.; You, K. K. J. Org. Chem. 1995, 60, 529.
90. For previous syntheses of (-)-indolizidine 207A (40), see: ref 27d and (a) Comins, D. L.; LaMunyon, D. H.; Chen, X. J. Org. Chem. 1997, 62, 8182. (b) Taber, D. F.; Rahimizadeh, M.; You, K. K. J. Org. Chem. 1995, 60, 529.
91. (a) Lipshutz, B. H.; Crow, R.; Dimock, S. H.; Ellsworth, E. L.; Smith, R. A. J.; Behling, J. R. J. Am. Chem. Soc. 1990, 112, 4063.
92. (b) Lipshutz, B. H. In Organometallics in Synthesis; Schlosser, M., Ed.; Wiley: Chichester, 1994; p 315.
93. Back, T. G.; Krishna, M. V. J. Org. Chem. 1987, 52, 4265; the general method of ref 18 was used in the preparation of 1c.
94. 1H NMR spectra attributable to the proton at the stereocenter (C-2) of the keto tautomer. The diastereotopic nature of the methylene protons in 7a and 7b is possibly due to asymmetry caused by intramolecular hydrogen bonding between the sulfone oxygen atoms and the hydroxyl groups of the enol tautomers, resulting in torsion of the arylsulfonyl moieties relative to the pyrrole rings. The averaging of NMR signals of the keto and enol forms would occur if equilibration of the tautomers was sufficiently rapid on the NMR time scale. This appears to be unlikely but cannot be completely ruled out. For a kinetic study of the tautomerization of other 3-hydroxypyrroles, see: Capon, B.; Kwok, F. J. Am. Chem. Soc. 1989, 111, 5346.
95. Estermann, H.; Seebach, D. Helv. Chim. Acta 1988, 71, 1824.
96. The racemic amino alcohol is a known compound: Bartoli, G.; Cimarelli, C.; Marcantoni, E.; Palmieri, G.; Petrini, M. J. Org. Chem. 1994, 59, 5328.
97. (a) Back, T. G. In Organoselenium Chemistry - A Practical Approach; Back, T. G., Ed.; Oxford University Press: Oxford, 1999; Chapter 5, p 105.
98. (b) Back, T. G.; Collins, S.; Krishna, M. V. Can. J. Chem. 1987, 65, 38.
99. Compound 1d was reported previously (ref 18c), but no spectroscopic data was provided.
100. Iwata, N.; Morioka, T.; Kobayashi, T.; Asada, T.; Kinoshita, H.; Inomata, K. Bull. Chem. Soc. Jpn. 1992, 65, 1379.