Evidence for a concerted [4 + 1]-cycloaddition between electron-rich carbenes and electron-deficient dienes

Organic Letters

Volumn 9, Issue 26, 2007, Pages 5361-5363

  Boisvert, Luc ^a   Beaumier, Francis ^a   Spino, Claude ^a  

^a UNIVERSITÉ DE SHERBROOKE   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 38349097983     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol702172t     Document Type: Article

References (18)

1. (a) Carruthers, W. Cycloaddition Reactions in Organic Synthesis; Pergamon Press: Oxford, U.K., 1990.
2. (b) Oppolzer, W. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Paquette, L. A., Eds.; Pergamon Press: Oxford, U.K., 1991; Vol. 5, p 315.
3. (c) Nicolaou, K. C.; Snyder, S. A.; Montagnon, T.; Vassilikogiannakis, G. Angew. Chem., Int. Ed. 2002, 41, 1668-1698.
4. Spino, C.; Rezaei, H. K. Dupont-Gaudet, F. Bélanger, J. Am. Chem. Soc. 2004, 126, 9926-9927.
5. Rigby, J. H.; Wang, Z. Org. Lett. 2003, 5, 263-264.
6. (a) Rigby, J. H.; Cavezza, A.; Ahmed, G. J. Am. Chem. Soc. 1996, 118, 12848-12849.
7. (b) Rigby, J. H.; Cavezza, A.; Heeg, M. J. J. Am. Chem. Soc. 1998, 120, 3664-3670.
8. For a review on many uses of such carbenes as well as mechanistic considerations, see: Warkentin, J. J. Chem. Soc., Perkin Trans. 1 2000, 2161-2169 and references therein.
9. See ref 5 and: (a) El-Saidi, M.; Kassam, K.; Pole, D. L.; Tadey, T.; Warkentin, J. J. Am. Chem. Soc. 1992, 114, 8751-8752.
10. (b) Kassam, K.; Pole, D. L.; El-Saidi, M.; Warkentin, J. J. Am. Chem. Soc 1994, 116, 1161-1162.
11. Nair has intercepted ionic intermediates derived from dimethoxy-carbene 2 with a variety of electrophiles. See: (a) Nair, V.; Vinod, R. A. U.; Bindu, S.; Sreekanth, A. R.; Mathen, J. S.; Balagopal, L. Acc. Chem. Res. 2003, 36, 899-907.
12. (b) Nair, V.; Bindu, S.; Sreekumar, V.; Balagopal, L. Synlett 2003, 1446-1456. See also:
13. (c) Nakamura, M.; Isobe, H.; Nakamura, E. Chem. Rev. 2003, 103, 1295-1326.
14. We wish to note that, if these cycloadditions were proceeding via ionic intermediates, such as 21, that would collapse before any bond rotation occurred, the stereochemical result would be equivalent to that of a concerted reaction. Proving or disproving "true concertedness" will require many more experiments and calculations, and it is beyond the scope of this study.
15. Fujimoto, H.; Hoffmann, R. J. Phys. Chem. 1974, 78, 1167-1173.
16. There are few examples of [4 + 1 ]-cycloadditions involving carbenes believed to be concerted. See: (a) Burger, U.; Gandillon, G. Tetrahedron Lett. 1979, 20, 4281-4284.
17. (b) Le, N. A.; Jones, M., Jr.; Bickelhaupt, F.; de Wolf, W. H. J. Am. Chem. Soc. 1989, 111, 8941-8943.
18. (c) Kraakmna, P. A.; de Wolf, W. H.; Bickelhaupt, F. J. Am. Chem. Soc. 1989, 111, 8534-8535 and references cited therein.