Construction of 4-(Methylthio)isochromenones Skeleton through Regioselective Intramolecular Cyclization of 2-Alkynylbenzoate Mediated by DMSO/[D-6]DMSO and SOCl2

摘要

DMSO/SOCl2 was found to be an effective system for the intramolecular cyclization of 2-alkynylbenzoates or 2-alkynylbenzoic acids, which can afford biologically interesting 4-(methylthio)isochromenones through regioselective electrophilic 6-endo-dig cyclization. DMSO plays the roles of both solvent and sulfur source and can also be replaced with its deuterated counterpart [D-6]DMSO, enabling the incorporation of the SCD3 moiety into the isochromenone skeleton.