One-Pot Synthesis of 2,5-Disubstituted Oxazoles

Significance

Reported is a concise one-pot three-step amidation, Pd-catalyzed acylation, and cycloisomerization procedure for the synthesis of 1-(hetero)aryl-2-[2-(hetero)aryloxazol-5-yl] ethanones from propargyl amine and acid chlorides in moderate to good overall yields. Anhydrides may be used as replacements of acid chlorides in the first step allowing access to 2-trifluoromethyl derivatives; carbonylative Sonogashira coupling can be used equally well in the second step. The structures have been confirmed by X-ray crystal structure analysis of one of the products.