The Alkylation of Ketone Enolates in the Presence of Triethanolamineborate. Control of Polyalkylation

Abstract

The formation of polyalkylated products is a major source of difficulty in the alkylation of ketone enolates. To some extent, this difficulty can be minimized by the use of lithium rather than sodium or potassium enolates.³ We have observed that triethylboron serves as an effective additive to minimize polyalkylation.⁴ For example, treatment of a THF solution of the sodium enolate of cyclohexanone with one equivalent of methyl iodide produces major amounts of dimethylated ketones, while the same reaction conducted in the presence