Crystal and molecular structure of 2-(4-bromophenyl)-r-2,4,4,c-6-tetramethyl-1,3-dioxan

Abstract

The crystal structure of the title compound (II) has been determined from diffractometer data by the heavy-atom method and refined by full-matrix least-squares techniques to R 0·12 for 635 reflections. The crystals are orthorhombic, space group Pbca with Z= 8 in a unit cell of dimensions a= 2765(3), b= 795(1), c= 1316(1) pm. The conformation of the 1,3-dioxan ring is a deformed chair with the phenyl substituent axial. This phenyl group has a short non-bonded distance of ca. 320 pm with the axial methyl group on C(4) and there is evidence of strain in the 1,3-dioxan ring. The structure is correlated with ¹H n.m.r. data for some model 1,3-dioxans.