Process for the stereoselective hydrogenation of cyclic compounds

摘要

The process of hydrogenation by means of elemental gaseous hydrogen in the presence of a hydrogenation catalyst applies to any cyclic compound possessing nonaromatic unsaturation, having a hydroxyl substituent at an asymmetric centre of the ring, and a carbon-carbon double bond which, after saturation by hydrogen, gives rise to an additional asymmetric centre in the ring. A stereoselective hydrogenation is produced which consists in the increased ease with which the H2 atom can approach the ring from the side where the -OH group is situated when working in the presence of a nickel catalyst whose active surface has, to a substantial degree, been deactivated by treatment with a modifier. The process applies, for example, to the preparation of d-isomenthol from d-trans-piperitol.