Comparative Mechanistic Study of the Reaction of Benzophenone with n-BuMgBr and n-BuLi

Article abstract of DOI:10.1021/jo00007a056

Substituent effects on reactivity and product distribution (addition vs reduction) were determined for the reactions of benzophenones with n-BuMgBr and n-BuLi at 0 deg C.In case of the reaction with n-BuMgBr, meta and para-substituted benzophenones gave a reasonably linear Hammet plot, from which the ρ value of 1.45 was calculated, while ortho-substituted derivatives deviated downward from the correlation line.In contrast, the reaction with n-BuLi exhibit very small substituent effects on reactivity.The product distrubution is highly dependent on substituents in the n-BuMgBr reaction, whereas it is essentially independent of substituents in the n-BuLi reaction.Mechanistic differences between the reactions of these two reagents are discussed on the basis of these experimental results.