THE ROLE OF O_2p-P(IV), N_2p-P(IV) AND SIMILAR INTERACTIONS IN HETEROATOM CHEMISTRY

Abstract

Phosphines having o-methoxyphenyl or o-(N,N-dimethylaminophenyl) groups bonded to the phosphorus atom exhibit moderate anchimeric assistance effects, attributable to through space O_2p-P(IV) or N_2p-P(IV) interactions, in reactions with alkyl halides. These S_N2 reactions have early transition states, and that is why the anchimeric assistance effects are only moderate. Quaternary phosphonium salts having o-methoxyphenyl groups bonded to phosphorus undergo slow alkaline decomposition reactions as expected because of O_2p-P(IV) interactions, but unusual effects are operative when o-(N,N-dimethylaminophenyl) groups are bonded to the phosphorus atom. Spectra of these types of compounds also show unusual characteristics. This review article provides rationalizations of these unusual data partly in terms of through space O_2p-P(IV) and N_2p-P(IV) interactions

Key Words:

• Anchimeric assistance
• alkylation
• phosphines
• phosphonium salts
• phosphoranes
• neighboring group interactions.