Transition-metal-free visible light-promoted photoredox oxidative dehydrogenative cyclization: expeditious approach to 1,2,4-thiadiazoles

Abstract

A novel visible-light-catalyzed oxidative N-S bond formation for the synthesis of 3,5-disubstituted 1,2,4thiadiazoles has been developed. This protocol features a metal-free approach, green oxidant, room temperature process, broad substrate scope, good functional group tolerance, excellent yields and a one-pot reaction without the isolation of the intermediates.

Directed evolution of Escherichia coli surface-displayed Vitreoscilla hemoglobin as an artificial metalloenzyme for the synthesis of 5-imino-1,2,4-thiadiazoles

“…On the basis of the previous literature 10,53,54 and our earlier study on VHb Co -catalyzed aerobic oxidation, 34,35 the mechanism of this reaction was proposed as shown in Scheme 2. First, amidines ( 1 ) and isothiocyanates ( 2 ) were coupled spontaneously to generate thiourea intermediate 4 .…”