Molecular and crystal structures of stereoisomeric 2R,3R,6S-2-(1 ' S-hydroxy-1 '-biphenylyl)- and 2R,3R,6S-2-(1 ' R-hydroxy-1 '-biphenylyl)methyl-3-methyl-6-isopropylcyclohexanones

It was established by X-ray diffraction analysis that 2-(1'-hydroxy-1'-biph enylyl)methyl-3-methyl-6-isopropylcyclohexanone, one of the minor products of the directed aldol reaction of (-)-menthone bromomagnesium enolate with 4-phenylbenzaldehyde, has the 2R,3R,6S,1'R configuration. The characteristi c features of the spatial structure of this beta-hydroxyketone were compare d with those of the major stereoisomeric product of the above-mentioned rea ction. The latter has the 2R,3R,6S,l'S configuration. In the crystals, both stereoisomer; have the cyclohexanone ring in a chair-like conformation wit h the three substituents in equatorial positions and are characterized by t he presence of the annelated (cis-fused) pseudoring with an -OH...O=C< intr amolecular hydrogen bond. The structures of the stereoisomers differ in the orientation of the aryl group and the hydrogen atom at the C(1') chiral ce nter with respect to the cyclohexanone ring. The results of X-ray diffracti on analysis were compared with the data of molecular mechanics calculation for the energetically most favorable conformations of the isolated molecule s of beta-hydroxyketones under study.