Synthesis of Imidazoles and Oxazoles by Aldimine Cross-Coupling

Significance

Reported here are the syntheses of tetrasubstituted imidazoles and trisubstituted ­oxazoles in one or two steps from α-acylamino-imines 5 which are readily obtained by 1,2-addition of N-monosubstituted α-aminonitriles 1 to N-acylimines 2. The intermediates 3 are subjected to the next DBU-catalyzed step without purification to give imidazoles 4 and intermediates 5; the cyclization directly to 4 is promoted by bulky substituents in the 5-position. The intermediates 5 are converted into oxazoles 6 in simple steps and purification is then achieved by column chromatography.