Influence des interactions de torsion dans les reactions d'addition sur les cyclohexanones. interpretation generale du deroulement sterique des reactions des hydrures ou des organomagnesiens sur les cyclohexanones

The addition of allyl and butenyl Grignard reagents to 4-t-butylcyclohexanone affords a greater proportion of the equatorial alcohols than is formed from the corresponding saturated Grignard reagents (propyl and s-butyl). In the case of the allyl Grignard reagent, the equatorial alcohol is the major product. Lithium aluminium hydride reduction in ether at 0° of cis and trans 4-t-butyl-2-methyl-cyclohexanone and cis and trans 4-t-butyl-2-chlorocyclohexanone affords mixtures of epimeric alcohols in ratios of equatorial to axial OH 8.4:1, 20:1, 4.2:1, and >70:1 respectively. These results fit in well with the view that polar interactions and torsional strain are both important in determining the steric course of the reaction.