Organosilicon compounds. Part XLIII. Preparation of aryl sulphones by desilylation or destannylation

Abstract

Treatment of an aryltrimethylstannane (X·C₆H₄·SnMe₃) with a preformed arenesulphonyl chloride–aluminium chloride (Y·C₆H₄·SO₂Cl,AlCl₃) complex in methylene chloride has been used to give the diaryl sulphone X·C₆H₄SO₂·C₆H₄·Y in moderately good yield; examples are the sulphones with X and Y as follows: H, H (62%); p-Me, H (62); H, p-Me (61); p-OMe, H (65); p-F, H (58); H, p-Me₃Si (57); H, p-Ph (53). The methanesulphonyl chloride–aluminium chloride complex has been used similarly to give the aryl methyl sulphones p-X·C₆H₄·SO₂Me, with X = H (58%), F (58), or Me (55), and also mesityl methyl sulphone (31%).

Aryltrimethylsilanes similarly gave the expected sulphones when treated with Y·C₆H₄·SO₂Cl,AlCl₃ complexes, but there was sometimes contamination by isomeric products; e.g. the products from p-tolyl- or p-methoxy-phenyltrimethylsilane and the benzenesulphonyl chloride–aluminium chloride complex included some o-tolyl or o-methoxyphenyl phenyl sulphone. (However, m-tolyltrimethylsilane and benzenesulphonyl chloride in carbon disulphide in presence of aluminium chloride gave phenyl m-tolyl sulphone in 64% yield.) The disulphone 4,4′-bis(phenylsulphonyl)biphenyl was obtained (47%) from 4,4′-bistrimethylsilylbiphenyl and the benzenesulphonyl chloride–aluminium chloride complex, and (63%) from phenyltrimethylsilane and the 4,4′-bis(chloro-sulphonyl)biphenyl–bis(aluminium chloride) complex.

Treatment of p-trimethylsilylbenzenesulphonyl chloride with an excess of benzene or toluene in the presence of aluminium chloride gave phenyl p-trimethylsilylphenyl sulphone (87%) and p-tolyl p-trimethylsilylphenyl sulphone (76%), respectively.