A Facile Method for Activation of Carboxylic Acids

1,1′-Oxalyldiimidazole, -1,2,4-triazole, and -1,2,3,4-tetrazole were prepared in situ from oxalyl dichloride and corresponding 1H-azoles. The 1,1′-oxalyldiazoles converted carboxylic acids and their salts into 1-acylazoles.