Electrochemical Oxidative Intramolecular N–S Bond Formation: Synthesis of 3-Substituted 5-Amino-1,2,4-Thiadiazoles

Abstract

A facile and efficient protocol for the synthesis of 3-substituted 5-amino-1,2,4-thiadiazoles has been developed through the electro-oxidative intramolecular dehydrogenative N–S bond formation of imidoyl thioureas. Various 1,2,4-thiadiazole derivatives were synthesized in good to excellent yields with broad substrate scope and excellent functional group tolerance under catalyst- and oxidant-free electrolytic conditions at room temperature.

H2O2‐Mediated Synthesis of 1,2,4‐Thiadiazole Derivatives in Ethanol at Room Temperature

“…In 2020, Liu, Yang, and Zhou et al. developed an electrochemical method for the synthesis of 1,2,4‐ thiadiazoles [14f] …”

Electrifying green synthesis: recent advances in electrochemical annulation reactions

“…169 Yang and co-workers describe a facile and efficient protocol for the synthesis of 3-substituted 5-amino-1,2,4-thiadiazoles 143 that avoids the use of metal catalysts and stoichiometric oxidants (Scheme 39). 170 The thiadiazoles were obtained via electrochemical oxidative intramolecular dehydrogenative N-S bond formation with imidoyl thioureas 142, in yields of up to 92%. The reaction was carried out using various imidoyl thioureas in the presence of MeCN at room temperature, and an undivided cell was equipped with a carbon rod anode and a Pt plate cathode under a 10 mA constant current using 0.03 M n-Bu 4 NBF 4 as the electrolyte.…”

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

“…[24][25][26][27][28][29][30][31] Most recently, an elegant protocol has been published via the electro-oxidative intramolecular dehydrogenative N-S bond formation of imidoyl thioureas (Scheme 1, c). 32 Despite major progress in the field, the use of transition-metal catalysts or oxidants is still standard, which affects atom economy and environmental issues. Therefore, it is desirable to develop a more pratical and environmentally friendly method for the synthesis of 3,5disubstituted 1,2,4-thiadiazoles.…”