Conformational study of 6-p-bromophenyl-1,4-oxathian-2-one

Abstract

The crystal structure of the title compound was determined by X-ray diffraction. The crystals have monoclinic symmetry with a= 7.129(4), b= 8.698(6), c= 16.633(4)Å, β= 97.13(6)°, and space group P2₁/c. For 2 001 observed independent reflections collected with a four-circle diffractometer the R-factor reached 0.042 after block-diagnol least-squares refinement. The conformation of the lactone ring is a perfect boat with a planar ester group. The aromatic ring is nearly perpendicular to the bottom of the boat. The conformation of the lactone in solution is discussed in relation to the solid-state structure and on the basis of n.m.r. and dipole measurements.