Categories: Synthesis of N-Heterocycles, Synthesis of S-Heterocycles >

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.

Sodium carbonate promotes a facile synthesis of 5-amino-1,2,4-thiadiazoles and 5-amino-1,2,4-selenadiazoles in good yields with elemental sulfur and selenium in the presence of air as the green oxidant. The reaction offers low cost, low toxicity, and stable sulfur and selenium sources, water as the sole byproduct, simple operation, and a broad substrate scope.
J.-X. Lin, G.-H. Liu, L.-Q. Liu, Y.-C. Wang, Y. He, J. Org. Chem., 2024, 89, 101-110.

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.