Rearrangement of 4-oxothiochroman-1-io(bismethoxycarbonyl)methanides to tetrahydro-1-benzothiepin-5-ones
Abstract
Heating thiochroman-4-ones with dimethyl diazomalonate without solvent or in refluxing toluene in the presence of copper(II) sulphate gave the corresponding bismethoxycarbonylmethanides (4) and dimethyl 5-oxo-2,3,4,5-tetrahydro-1-benzothiepin-2,2-dicarboxylates (5). Treatment of the sulphonium methanides (4) with triethylamine afforded (5).