The formation of 2-oxopropyl-2-oxopropylidenediphenylphosphorane. Crystal and molecular structure of its lithium enolate

Abstract

An assignment of the constitution of the compound obtained in the reaction of Ph₂PSiMe₃ with BrCH₂COCH₃(1) is made. Subsequent dehydrobromination is reported to give 2-oxopropyl-2-oxopropylidenediphenylphosphorane (4) instead of diphenylphosphinoacetone (2). Lithiation of (4) yields the corresponding enolate (6). The crystal and molecular structure of (6) has been resolved by X-ray diffraction analysis, and spectroscopic properties of (4) are interpreted on the basis of MNDO calculations.