Synthesis of Dipeptide, Amide, and Ester without Racemization by Oxalyl Chloride and Catalytic Triphenylphosphine Oxide

An efficient triphenylphosphine oxide-catalyzed amidation and esterification for the rapid synthesis of a series dipeptides, amides, esters is described. This reaction applicable to challenging couplings hindered carboxylic acids with weakly nucleophilic amines or alcohols, giving products in good yields (67–90%) without racemization. system employs highly reactive intermediate Ph3PCl2 as activator carboxylate catalytic manner drives completion short time (less than 10 min).