Homolytic aromatic substitution of heterocyclic compounds. Part I. Decomposition of phenylazotriphenylmethane in thiophen

Abstract

The reaction of thiophen with phenylazotriphenylmethane has been investigated. The percentage of the 2-phenyl-thiophen relative to that of the 3-isomer is considerably lower than those obtained with other phenylating agents and is highly dependent on the experimental conditions as well as on the working-up of the reaction mixtures. This is attributed to the trapping of the σ-complex leading to the 2-phenylthiophen by the triphenylmethyl radical to give two isomeric 2,5-dihydro-2-phenyl-5-triphenylmethylthiophens.