(Pyridine)(tetrahydroborato)zinc Complex, [Zn(BH4)2(py)], as a New Stable, Efficient and Chemoselective Reducing Agent for Reduction of Carbonyl Compounds

Abstract

(Pyridine)(tetrahydroborato)zinc complex, <TEX>$[Zn(BH_4)_2(py)]$</TEX>, as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and a, β-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent.