3,3′-(Phenylphosphinylidene)bis[2(3H)-benzoxazolone] and 3,3′-(Phenylphosphinylidene)bis[2(3H)-benzothiazolone]. New Activating Agents

New activating agents, 3,3′-(phenylphosphinylidene)bis[2(3H)-benzoxazolone] (4) and 3,3′-(phenylphosphinylidene)bis[2(3H)-benzothiazolone] (5), were readily prepared by the reaction of phenylphosphonic dichloride (3) with 2(3H)-benzoxazolone (1) and 2(3H)-benzothiazolone (2) respectively in the presence of triethylamine at room temperature. The new activating agents 4 and 5 were found to be useful for the preparation of amides, esters, and dipeptides under mild conditions. Furthermore, the direct poly-condensation of isophthalic acid with aromatic diamines using the activating agent 4 in the presence of pyridine proceeded fast at room temperature to produce polyamides with inherent viscosities up to 0.80 dL/g.