Reaction of benzyne with carbon disulphide: formation and reaction of 1,3-benzodithiol-2-ylidene

Abstract

Benzyne, generated by oxidation of 1-aminobenzotriazole and by decomposition of benzenediazonium-2-carboxylate or 2-carboxybenzenediazonium chloride, reacts with carbon disulphide to give the resonance-stabilized and nucleophilic carbene 1,3-benzodithiol-2-ylidene. This carbene can be effectively trapped by protic substrates by protonation to give the 1,3-benzodithiolylium ion, which further reacts with nucleophiles to yield final products, although in the absence of protic substrates it dimerizes to give bi-(1,3-benzodithiol-2-ylidene). However, the reaction of carbon disulphide with benzyne generated from 1-(2-carboxyphenyl)-3,3-dimethyltriazene gives products unexplainable in terms of the carbene intermediate.