No abstract

Zeolite BEA is found to be the first stereoselective and regenerable heterogeneous catalyst for the Meerwein-Ponndorf-Verley reduction of 4-tert-butylcyclohexanone to cis-4-tert-butylcyclohexanol.The Meenvein-Ponndorf-Verley (MPV) reduction of aldehydes and ketones is a highly selective reaction that can be performed under mild conditions, without affecting other reducible functional groups. The hydrogen donors are easily oxidizable secondary alcohols and the reductions are usually catalysed by metal alkoxides such as A1(OPrl)3. The catalytic activity of metal alkoxides is related to their Lewis acidic character in combination with ligand exchangeability. A major advantage of heterogeneous over homogeneous catalysts is that they can easily be separated from the liquid reaction mixture. However, only a few examples of heterogeneously catalysed MPV reductions have been reported.'The stereoselective reduction of 4-tert-butylcyclohexanone to cis-4-tert-butylcyclohexanol is a commercially interesting conversion. The cis-alcohol is in use on a substantial scale as an intermediate in the fragrance industry. However, the homogeneous MPV reduction of 4-tert-butylcyclohexanone cata-

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