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Synthesis of 1,2,4-thiadiazoles

An electro-oxidative intramolecular dehydrogenative N-S bond formation of imidoyl thioureas provides a broad range of 3-substituted 5-amino-1,2,4-thiadiazoles derivatives in good to excellent yields with excellent functional group tolerance under catalyst- and oxidant-free conditions at room temperature.
Z. Yang, J. Zhang, L. Hu, L. Li, K. Liu, T. Yang, C. Zhou, J. Org. Chem., 2020, 85, 3358-3363.

I2-mediated oxidative C-N and N-S bond formations in water enable a metal-free, environmentally benign and convenient strategy for the synthesis of 4,5-disubstituted/N-fused 3-amino-1,2,4-triazoles and 3-substituted 5-amino-1,2,4-thiadiazoles from isothiocyanates. The scalable protocols exhibited excellent substrate tolerance.
N. Jatangi, N. Tumula, R. K. Palakodety, M. Nakka, J. Org. Chem., 2018, 83, 5715-5723.

An intramolecular oxidative S-N bond formation of imidoyl thioureas mediated by phenyliodine(III) bis(trifluoroacetate) enables an efficient, metal-free synthesis of 3-substituted-5-arylamino-1,2,4-thiadiazoles. The protocol offers broad substrate scope, very short reaction times and very good yields.
A. Mariappan, K. Rajaguru, N. M. Chola, S. Muthusubramanian, N. Bhuvanesh, J. Org. Chem., 2016, 81, 6573-6579.