Meerwein–Ponndorf–Verley reduction of cycloalkanones over magnesium–aluminium oxide

Abstract

MgO–Al₂O₃ obtained from layered double hydroxide has been studied as a catalyst in the Meerwein–Ponndorf–Verley (MPV) reduction of cycloalkanones and substituted cyclohexanones in the liquid phase. Conversions for cycloalkanones always exceeded 95% and the selectivity was 100% within the first 10 h of reaction. In the MPV reduction of 4-tert-butylcyclohexanone to 4-tert-butylcyclohexanol a high stereoselectivity (cis : trans ratio > 12) was obtained. This stereoselectivity is explained by the transition-state selectivity imposed by the adsorption complex. For the reduction of cyclohexanone, a recycling test showed that the catalyst can be reused up to four times without losing more than 10% catalytic activity.