[(Ph)2(NMe2)C(OLi)⋅THF]2: Crystal Structure of the Tetrahedral Intermediate Formed in the Reaction of N,N-Dimethylbenzamide and Phenyllithium

Abstract

Information on the reaction path for the 1,2-eliminiation of LiNMe₂ to form benzophenone is provided by the X-ray crystal structure analysis of the tetrahedral adduct [(Ph)₂ (NMe₂ )C(OLi)⋅THF]₂ (a portion of the structure is shown schematically), which is prepared from N,N-dimethylbenzamide and phenyllithium. A N1-Li1 interaction, which is not observed, would lead to loss of the anomeric effect (n_N →σ^*_C-O ) as well as high conformational strain along the C1-N1 bond.