Cyclization of 1,2,4-triazenes to 1,2,4-triazoles using oxidizing reagents—NaClO, Ca(ClO)2, Dess–Martin periodinane and Leyʹs TPAP/NMO

A simple and efficient approach to 1,3,5-trisubstituted 1,2,4-triazoles via cyclization of 1,2,4-triazenes employing commonly used oxidizing agents such as NaClO, Ca(ClO)2, Dess–Martin periodinane and Leyʹs oxidizing agent (TPAP/NMO) is described. The reaction proceeds under mild conditions and is compatible with various functional groups. Extension of this approach to prepare triazoles on solid support has also been investigated.