A new route to thiopyran S, S-dioxide derivatives via an overall ring-enlargement protocol from 3-nitrothiophene

Abstract

(1 E,3 Z)-1-Aryl-4-methanesulfonyl-2-nitro-1,3-butadienes ( 8), derived from the initial ring-opening of 3-nitrothiophene ( 5), have been found to undergo a facile base-induced cyclization leading to thiopyran S, S-dioxides ( 9), thus furnishing a further example of effective ring-enlargement from 5- to 6-membered sulfur heterocycles. Compounds 9 are obtained as single racemic mixtures in satisfactory yields; they still contain a nitrovinylic moiety, which can be exploited for further modifications targeted to new derivatives endowed with either synthetic or pharmacological potentialities e.g., in the field of L-type Ca 2+-channel blockers.