Enhanced Regioselectivity of Yang Photocyclization in the Crystalline State

Organic Letters

Volumn 4, Issue 7, 2002, Pages 1071-1073

  Vishnumurthy, Kodumuru ^a   Cheung, Eugene ^a   Scheffer, John R ^a   Scott, Carl ^a  

^a UNIVERSITY OF BRITISH COLUMBIA   (Canada)

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EID: 0038559947     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol017134h     Document Type: Article

References (17)

1. Wagner, P. J. J. Am. Chem. Soc. 1967, 89, 5898.
2. Bernard, M.; Yang, N. C. Proc. Chem. Soc. 1958, 302.
3. Sauers, R. R.; Huang, S.-Y. Tetrahedron Lett. 1990, 31, 5709.
4. (a) Gudmundsdottir, A. D.; Lewis, T. J.; Randall, L. H.; Scheffer, J. R.; Rettig, S. J.; Trotter, J.; Wu, C.-H. J. Am. Chem. Soc. 1996, 118, 6167.
5. (b) Leibovitch, M.; Olovsson, G.; Scheffer, J. R.; Trotter, J. J. Am. Chem. Soc. 1998, 120, 12755.
6. (c) Cheung, E.; Kang, T.; Raymond, J. R.; Scheffer, J. R.; Trotter, J. Tetrahedron Lett. 1999, 40, 8729.
7. Wagner, P. J.; Pabon, R.; Park, B.-S.; Zand, A. R.; Ward, D. L. J. Am. Chem. Soc. 1994, 116, 589.
8. Wagner, P. J.; Kemppainen, A. E. J. Am. Chem. Soc. 1972, 94, 7495.
9. Yang photocyclization refers to the formation of cyclobutanols in Norrish type II photochemistry, a reaction that was first reported by Yang and Yang: Yang, N. C.; Yang, D. H. J. Am. Chem. Soc. 1958, 80, 2913.
10. According to Eliel and Wilen (Eliel, E. L.; Wilen, S. H. Stereochemistry of Organic Compounds; Wiley: New York, 1994; Chapter 7, p 30), if the melting point of the enantiomerically pure compound exceeds that of the racemate by 25°C or more, the probability of conglomerate formation is high. Generally, the difference in melting point is in the range 25-35 °C, although differences of 20°C or even less are not uncommon.
11. 3, R = 0.055.
12. 3, R = 0.051.
13. 3, R = 0.046.
14. Ihmels, H.; Scheffer, J. R. Tetrahedron 1999, 55, 885.
15. Computer overlap of the X-ray structure with the calculated structure gives an average root-mean-square deviation between the two of 0.069 Å.
16. This is necessarily the case in the phenomenon of conformational polymorphism, whereby a given substance crystallizes in two or more different conformations as well as packing arrangements. For a discussion of conformational polymorphism, see: Bernstein, J. In Organic Solid State Chemistry; Desiraju, G. R., Ed.; Elsevier: Amsterdam, 1987; Chapter 13, pp 471-518. For an example of conformational dimorphs that undergo different photochemical reactions in the crystalline state, see: Lewis, T. J.; Rettig, S. J.; Scheffer, J. R.; Trotter, J. J. Am. Chem. Soc. 1991, 113, 8180.
17. This is necessarily the case in the phenomenon of conformational polymorphism, whereby a given substance crystallizes in two or more different conformations as well as packing arrangements. For a discussion of conformational polymorphism, see: Bernstein, J. In Organic Solid State Chemistry; Desiraju, G. R., Ed.; Elsevier: Amsterdam, 1987; Chapter 13, pp 471-518. For an example of conformational dimorphs that undergo different photochemical reactions in the crystalline state, see: Lewis, T. J.; Rettig, S. J.; Scheffer, J. R.; Trotter, J. J. Am. Chem. Soc. 1991, 113, 8180.