Réactions induites par les halogénures de pyridinium. XXIV. Sur la synthése de dibenzofurannes à partir de diméthoxy-2,2′ biphényles

Dibenzofurans were obtained by the cyelization of 2,2′-dihydroxybiaryls using pyridinium bromide. The 2,2′-dihydroxy-biaryls were obtained by demethylation via pyridinium chloride from 2,2′-dimethoxybiaryls. The dealkylation which is followed by cyelization into the dibenzofurans with pyridinium bromide is complicated by indirect transmethylation. Acyl derivatives of 2,2′-dimethoxybiaryles lose their acyl group when dealkylated by pyridinium halides, whether or not cyelization follows this process.