Van Leusen reaction

Van Leusen, the reaction is a reaction, and the name describes the reaction between a ketone of tosylmethyl isocyanide ( TosMIC ) in a nitrile. It was first described in 1977 and named after its discoverer Van Leusen. , The reaction with an aldehyde in place of the ketone so obtained an oxazole or imidazole.

Reaction mechanism

The reaction starts by the deprotonation of TosMIC to a carbanion, which is stabilized by the adjacent sulfone and nitrile groups. Nucleophilically attacks the carbanion at the carbon atom of the carbonyl. By one, by the Baldwin rules, 5 -endo -dig cyclization to a five-membered heterocycle which further reacts by cleavage of the tosyl moiety to give the oxazole forms. An aldimine, instead of an aldehyde ( for example from a Mannich reaction ) is responsive in a manner analogous to the imidazole.

A ketone used as the carbonyl component, no elimination can take place. The reaction proceeds through a tautomerism and ring opening. The open-chain intermediate finally eliminated the tosyl and by hydrolysis of the nitrile is formed as an end product.