Solid-phase synthesis of 3-amino-1,2,4-triazoles

A solid-phase synthesis of 3-amino-1,2,4-triazoles is described. Reaction of resin bound S-methylisothiourea 2 with carboxylic acids yielded resin-bound S-methyl-N-acylisothioureas 3, which reacted with hydrazines under mild conditions to afford the corresponding resin-bound 3-amino-1,2,4-triazoles 4 with regioselectivity. Following cleavage, the desired products 5 were obtained in good yields and purities.