DIASTEREOSELECTIVE REDUCTION OF CYCLOHEXANONES WITH DIISOBUTYLALUMINUM PHENOXIDES IN TERMS OF THE ISOINVERSION PRINCIPLE

The diastereoselectivity of the reduction of 2-substituted cyclohexano nes 1-6 with 4-substituted diisobutylaluninium phenoxides a-d has been investigated as a function of temperature, The high-temperature regio n is found to be dominated by hydride transfer, which is controlled by steric as well as electronic effects, However, at low temperatures th e Meerwein-Pondorf-Verley reaction gains in importance, This phenomeno n is quantified by an isoinversion relationship.