PRACTICAL PROCEDURE FOR THE CHEMOSELECTIVE REDUCTION OF ESTERS BY SODIUM BOROHYDRIDE. EFFECT OF THE SLOW ADDITION OF METHANOL.

Article abstract of DOI:10.1246/bcsj.57.1948

The effect of solvents on the reduction of esters was examined with readily available sodium borohydride which is known to be incapable of reducing such functional groups. In mixed solvents of t-butyl alcohol-methanol or tetrahydrofuran-methanol, various carboxylic esters and lactones were found to be reduced by sodium borohydride to the corresponding alcohols or diols in high yields. Slow addition of methanol to the refluxing mixture of ester and sodium borohydride in t-butyl alcohol or tetrahydrofuran was essential to achieve effective reduction. On the other hand, each individual solvent, methanol or t-butyl alcohol, was not effective for the reduction.