Nuclear magnetic resonance and infrared study of lithium coordination by phosphonates and phosphine oxides R2P(O)CH2COY and their carbanions. Comparison between ketone, ester, and amide COY groups

Abstract

Lithiated carbanionic chelates α to P(O) groups are formed from four title compounds. Their infrared and 13C and 31P nuclear magnetic resonance spectra show that chelation induces peculiar structural perturbations that depend upon the nature of Y. The corresponding neutral precursors 1–4 are able to form bidentate coordinates with the Li cation, which can be observed in THF when Y = OMe or NMe2 but in benzene only when Y = Me. They are probably intermediates in the lithiated base deprotonation of neutral compounds 1–4.