First Evidence for the Existence of a Phosphathioketene

Abstract

A novel phosphacumulene, the title compound 2, is discussed as an unstable precursor of 3 in the reaction sequence outlined below. The unsymmetrical [2 + 2]-cycloaddition in the dimerization of 2 to 3 corresponds to that observed with ketenes (R = 2,4,6-tri-tert-butylphenyl).