Organocatalytic asymmetric addition of aliphatic thiols to nitro olefins and nitrodienes
作者:Rafał Kowalczyk、Anna E. Nowak、Jacek Skarżewski
DOI:10.1016/j.tetasy.2013.03.007
日期:2013.4
5-bis(trifluoromethyl)phenyl thiourea derivative of readily available chiral 1-benzyl-3-aminopyrrolidine was an effective organocatalyst for the asymmetric sulfa-Michael reaction. The adducts of aliphatic thiols to nitroolefins and nitrodienes were formed in good yields and with up to 87% ee in the presence of 2.5 mol % of the organocatalyst.
The catalyst 1-[(3R,4S)-1-benzyl-4-phenyl-pyrrolidin-3-yl]-3-[3,5-bis(trifluoromethyl)phenyl]urea (8) designed based on 1-[(3R)-1-benzylpyrrolidin-3-yl]-3-[3,5-bis(trifluoromethyl)phenyl]thiourea (4) and 1,3-bis[(3R,4S)-1-benzyl-4-phenylpyrrolidin-3-yl]urea (7) exhibited potent catalytic activity for the asymmetricMichaeladdition of thiols to β-nitrostyrenes. A mere 2 mol % of the catalyst afforded