Journal article

Zinc Bromide Promoted Coupling of Isonitriles with Carboxylic Acids To Form 2,4,5-Trisubstituted Oxazoles

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.


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