EFFECT OF THE STRUCTURE OF DIMETHYLCYCLOHEXANONES ON THE RATE AND STEREOSELECTIVITY OF THEIR REDUCTION BY 2-PROPANOL IN THE PRESENCE OF RHCL(PPH3)3 AND RUCL2(PPH3)3

1. The rate of proton transfer from 2-propanol to the C=O groups of 3,4-, 3,5-, and 2,5-dimethylcyclohexanone in the presence of RhCl(PPh3)3 and RuCl2(PPh3)3 depends on the conformation and position of the substituents on the ring and the configuration of the ketone molecule. 2. A stereoisomer of dimethylcyclohexanone which has an axialmethyl group is reduced more slowly than the corresponding isomer with an equatorial substituent. The rate of the reaction is reduced most drastically in the case of the 2, 5-dimethylcyclohexanones. 3. The reduction of trans-3,4-and cis-3,5-dimethylcyclohexanones in the presence of RhCl(PPh3)3 results mainly in the formation of the thermodynamically less stable isomers, while approximately equal amounts of the eee and eea conformers of the alcohols form in a solution of RuCl2 (PPh3)3. The thermodynamically less stable eea isomer of 2, 5-dimethylcyclohexanol is preferentially synthesized from trans-2,5-dimethylcyclohexanone. © 1978 Plenum Publishing Corporation.