Deviant behavior: In a deviation from “normal” reactivity, isocyanides underwent co-trimerization with carboxylic acids in the presence of ZnBr2 to smoothly provide oxazoles (see scheme). The reaction is thought to occur by initial nucleophilic addition of the carboxylic acid to a ligated isonitrile molecule, followed by a sequence involving double migratory insertion, metal-salt elimination, acyl migration, cyclization, and dealkylation.