Formation of fused 1,3-benzothiaphospholes from fused 1,2,3-benzothiadiphospholes by a simple phosphorus-carbon exchange

Abstract

Treatment of fused 1,2,3-benzothiadiphospholes with acetyl chloride, in the presence of AlCl₃, leads to fused 1,3-benzothiaphospholes, in which an unexpected phosphorus-carbon exchange has occurred; a single crystal X-ray diffraction of the dimethyl derivative of this new heterocycle confirmed its structure and showed the cis-configuration between the phosphorus Ione pair and the 6-substituent.