Benzoyl-substituted thiirans and oxathioles. The synthesis and properties of 2-benzoyl-5-phenyl-1,3-oxathiole

Abstract

2-Benzoyl-5-phenyl-1,3-oxathiole (8) has been prepared and characterized. The chemical and spectral properties of this compound confirm our previous assignment of the structure of 2-benzoyl-2,4,5-triphenyl-1,3-oxathiole (2a) which had earlier been reported to be 2,3-dibenzoyl-2,3-diphenylthiiran (1a). Deuterium-labelling experiments have shown that no equilibrium occurs under mild conditions (120 °C) between the 2-benzoyl-5-phenyl-1,3-oxathiole (8) and the corresponding thiiran (15). At higher temperatures decomposition occurs. Upon rapid pyrolysis at 275 °C 1,2-dibenzoylethylene is formed.