Convenient synthesis of N-sulfonyl α-hydroxyamides via DMSO oxidation of N-alk-1-ynylsulfonamides

Abstract

ABSTRACT N-Arenesulfonyl α-hydroxyamides are conveniently synthesized from N-arylethynylsulfonamides (ynamides) via oxidation with dimethyl sulfoxide (DMSO) in the presence of equivalent of trifluoromethanesulfonic acid (TfOH) followed by treatment with water. In this reaction, ynamides are activated by protonation with TfOH and then undergo double DMSO nucleophilic addition and subsequent hydrolysis. Investigations on the substrate scope indicate N-arenesulfonyl and arylethynyl substituted ynamides proceed the oxidation well. Compared to the previous methods, the current method realizes the direct conversion from N-arylethynylsulfonamides to N-arenesulfonyl α-hydroxyamides with mild DMSO as a nucleophilic oxidant in the presence of strong acid trifluoromethanesulfonic acid.