Selective ortho-alkylation of phenols with sulphoxides via[2,3]sigmatropic rearrangement: synthesis of coumarins

Abstract

ortho-Alkylphenols have been prepared from phenol and dialkyl sulphoxides via[2,3]sigmatropic rearrangement, using thionyl chloride or phenyl chlorosulphinate as an activator of sulphoxides. In the same manner, ortho-phenylthiomethylphenol has been prepared in good yield. When ethyl phenyl sulphoxide, diallyl sulphoxide, and methyl methylsulphinylacetate were used as sulphoxides, none of the expected products were obtained. Salicylaldehyde has been prepared in moderate yield, when methyl methylthiomethyl sulphoxide was used as a sulphoxide. 3-(2-Hydroxyphenyl)propionic acid derivatives, which were obtained from substituted phenols and dimethyl 3,3′-sulphinyldipropionate, have been cyclized to give the corresponding coumarins in good yields.