Regiochemistry and stereochemistry of intramolecular [2+2] photocycloaddition of carbon-carbon double bonds to cyclohexenones
作者:D. Becker、M. Nagler、Y. Sahali、N. Haddad
DOI:10.1021/jo00014a040
日期:1991.7
The intramolecular [2 + 2] photocycloaddition mechanism of alkenes tethered by a three-methylene chain to cyclohexenones has been studied. It was found that the reversion from a 1,4-diradical intermediate to starting material is slow relative to the rate of photoadduct formation. Only ''straight'' closure was observed in the systems studied. For compounds 1-3 and 5, the assumption that the first bond is formed between the beta-carbon of the enone and C-4' leading to a 1,4-diradical is supported. For the formation of compounds 6-11, possible mechanisms are discussed.
Lewis Base Catalyzed, Enantioselective, Intramolecular Sulfenoamination of Olefins
作者:Scott E. Denmark、Hyung Min Chi
DOI:10.1021/ja5046296
日期:2014.6.25
A method for the enantioselective, intramolecular sulfenoamination of various olefins has been developed using a chiral BINAM-based selenophosphoramide, Lewis base catalyst. Terminal and trans disubstituted alkenes afforded pyrrolidines, piperidines, and azepanes in high yields and high enantiomeric ratios via enantioselective formation and subsequent stereospecific capture of the thiiranium intermediate with the pendant tosyl-protected amine.