Dissolving metal reduction of esters to alkanes. A method for the deoxygenation of alcohols

Abstract

Diverse carboxylic esters have been reduced with dissolving Group 1A metals. Using lithium in ethylamine, sterically hindered esters (RCO₂R′) were deoxygenated giving the alkane (R′H) whereas non-hindered esters regenerated the parent alcohol (R′OH). This permitted the selective deoxygenation of diesters. Conversely, potassium–sodium eutectic solubilised with 18-crown-6 in t-butylamine and tetrahydrofuran (THF) efficiently deoxygenated both hindered and non-hindered esters. In the absence of nucleophiles at ambient temperature the principal reaction of carboxylic ester radical anions was deoxygenation.