novel ring-expansion of thiochroman-4-one sulfonium methanides to tetrahydro-1-benzothiepin-5-ones

ABSTRACT

Heating thiochroman-4-ones with dimethyl diazomalonate in refluxing toluene in presence of copper sulphate gave the corresponding bismetho-xycarbonylmethanides [4] and ring-expansion product 2, 3, 4, 5-tetrahydro-1-benzothienpin-5-ones [5]. Treatment of [4] with triethylamine afforded ring-expansion product [5]