DIPHENYL (2,3-DIHYDRO-2-THIOXO-3-BENZOXAZOLYL)PHOSPHONATE - A NEW, REACTIVE ACTIVATING AGENT FOR THE SYNTHESIS OF AMIDES AND POLYAMIDES

A new activating agent for amide condensations, diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate (1), was readily prepared at room temperature by the reaction of 2-benzoxazolethiol (3) with diphenyl phosphorochloridate (2) in the presence of triethylamine (TEA) in benzene. The reaction of carboxylic acids with amines in the presence of 1 was investigated by two procedures, a two-step and a one-step procedure. Both procedures gave corresponding amides in high yields under mild conditions. The direct polycondensation of dicarboxylic acids with diamines by using the activating agent 1 in the presence of TEA proceeded smoothly at room temperature to produce polyamides with inherent viscosities up to 1. 2 dL g** minus **1.