4-Cyano-4'-[(4R)-4,5-epoxypentyloxy]biphenyl: a Pseudosymmetry Problem Solved with Synchrotron Data

Abstract

The title compound, 4′-[(4R)-4,5-epoxypentyloxy]-4-biphenylcarbonitrile, C18H17NO2, crystallizes in space group P21 with two independent molecules of identical chirality. The molecules differ significantly only in the conformation of the substituent containing the epoxide ring. With the exception of this ring, the structure approximates closely to the centrosymmetric space group P21/n, in which refinement can be achieved with the assumption of twofold disorder of orientation of the epoxide ring and a racemic material. The pseudosymmetry is resolved by a weak subset of h0l reflections (h + l = 2n), which are found to be significant in a synchrotron data set. The two rings of the biphenyl unit are essentially coplanar, in contrast to most 4-cyano-4′-(alkyloxy)biphenyl compounds.