for the synthesis of 2,4,5-trisubstituted oxazoles has been developed from the direct coupling of α-diazoketones with aryl or alkyl nitriles. The reaction proceeds through the formation of nitrilium ion by the nucleophic addition of nitrile onto diazo functionality followed by an intramolecular trapping of nitrilium ion by keto group. Both aryl, and alkyl nitriles underwent smooth cyclocondensation