The Crystal and Molecular Structure of (+)-1-Bromo-2-hydroxy-2-phenylethyl p-Tolyl Sulfoxide: The Bromohydrin of (+)-trans-β-Styryl p-Tolyl Sulfoxide

Abstract

Abstract The crystal structure of (+)-1-bromo-2-hydroxy-2-phenylethyl p-tolyl sulfoxide, a major isomer formed by the electrophilic addition of BrOH to (+)-trans-β-styryl p-tolyl sulfoxide (1), has been determined by the X-ray diffraction method. The crystal is hexagonal; space group, P62; a=15.61, c=10.82 Å, and Z=6. The final R value is 0.079. A helical chain of the hydrogen bond between hydroxyl and sulfinyl groups (O···O, 2.63 Å) is formed around the threefold screw axis. The absolute configuration has been determined to be Ss, Sc(1), Sc(2) from the Mo Kα anomalous scattering of bromine and sulfur atoms. The bromine atom is gauche to the sulfinyl oxygen across the C(1)–S bond and trans to the hydroxyl oxygen across the C(1)–C(2) bond. Based on the established absolute configuration of the title compound, a mechanism which involves the preferential formation of an intermediary bromonium ion is proposed for the addition of BrOH to 1.