The Reaction of Trimethylsilyl Esters with Metal Hydride Reducing Agents. Protection of Carboxylic Acids as Their Trimethylsilyl Ester During Hydroboration

Abstract

The previous report in the literature concerning the reduction of silyl esters of carboxylic acids used lithium aluminum hydride as the reducing agent and dealt with the reactivity and stereochemistry of the silicon atom with no mention of the fate of the carbonyl portion of the molecules.³ We felt that the reduction of trimethylsilyl esters could possibly lead to aldehydes or chemoselective reactivity and as such deserved further investigation. We wish to report here on the reaction of representative trimethylsilyl esters with sodium borohydride, lithium aluminum hydride (LAH), diisobutylaluminum hydride (DIBAH) and borane in THF (BH₃: THF). The results are shown in Table I.