On the behavior of bis(sulfonyl)nitrobutadienes towards primary amines: a convenient access to 1-alkyl-2-aryl-4-(phenylsulfonyl)pyrroles

Description

The conjugated bis(sulfonyl)nitrobutadienes 1 undergo, with primary amines, competitive MeSO2 replacement [vinylic substitution at C(1)] versus aza-Michael addition to the nitroethenyl C(3)–C(4) double bond. The latter pathway eventually leads to the trisubstituted pyrroles 2 and conditions have been optimized in order to maximize the yield of such polyfunctionalized heterocycles. Interestingly, in trifluoroethanol tetrasubstituted pyrroles 7 are also formed, thanks to a final aromatization via oxidation by 'endogenous' nitrite.

Additional details