Reactions of Aryldiazomethanes with Chloranil

Article abstract of DOI:10.1246/bcsj.53.726

The reactions of several aryldiazomethanes (1a: p-tolyl; 2b: phenyl; 1c: p-chlorophenyl) with chloranil gave stilbenes (3) and spiro-oxetanes (4) at 20 deg C in tetrahydrofuran or 1,2-dichloroethane.The isomer ratios of 3 were ca. 2 to 3:1 in favor of cis, depending on the solvents and on the substituents 1.In the case of 4, however, stable trans-isomers were selectively formed.On the other hand, the presence of added CH3OH supressed the formation of 3 and 4 and, instead induced redox reactions giving α,α-dimethoxyarylmethanes and tetrachlorohydroquinone (6).In these redox reactions, the acid decompositions of 1 with 6 were also found.However, the presence of CF3CH2OH allowed the formation of considerable amount of 3 and 4, along with the redox products.The mechanism of these reactions will be discussed.