Nucleophilic Displacements in Alkylphosphonates: P–O Versus P–C Bond Cleavage. A Combined DFT and Experimental Study

Abstract

Potential energy surfaces for the nucleophilic displacements at phosphorus in dimethyl methyl, chloromethyl, dichloromethyl, and trichloromethyl phosphonates have been computed by DFT methods. The results reveal that sequential introduction of chlorine substituents at the methyl group in methyl phosphonates increases the stability of transition states and intermediates, which facilitates P–C bond cleavage. While nonsubstituted dimethyl methylphosphonate may undergo exclusive P–O bond cleavage, the trichlorinated analogue reacts exclusively via P–C bond dissociation to form dichlorocarbene, which was trapped by various olefins to form the corresponding gem-dichlorocyclopropanes.

GRAPHICAL ABSTRACT

Keywords:

• Alkylphosphonates
• DFT
• potential energy surface
• dichlorocarbene
• gem-dichlorocyclopropanes