Generation of di-isopropylcarbamoyl-lithium from NN-di-isopropylformamide and t-butyl-lithium. Syntheses of α-hydroxy- and α-oxo-amides

Abstract

Detailed investigations of reaction conditions for optimum formation of di-isopropylcarbamoyl-lithium from NN-di-isopropylformamide and organolithium reagents have led to the development of a nearly quantitative procedure, using t-butyl-lithium in diethyl ether–tetrahydrofuran–pentane (4 : 4 : 1) at –95 °C. The species so formed reacts with electrophiles such as aldehydes, ketones, esters, and D₂O to give high yields of the expected products. Less reactive electrophiles such as alkyl iodides also react, but yields are lower and these reactions are of little synthetic significance. Benzyl bromide is sufficiently reactive, but the initial product is acidic, so that deprotonation and further alkylation occur.