TRANS-2-PHENYLTETRAHYDROPYRAN-3-YLMETHYL P-TOLUENESULFONATE

trans-2-Phenyltetrahydropyran-3-ylmethyl p-toluene-sulfonate, C19H22O4S, (6), crystallizes with two molecules (A, B) in the asymmetric unit. The shortest intermolecular distance between the independent species involving non-H atoms only (C...O) is 3.138 (4) angstrom. The bulky substituents in (6) are oriented trans to each other and, as expected, occupy equatorial positions (ee). However, semi-empirical calculations on one precursor of (6), 2-phenyltetra-hydropyran-3-carbaldehyde (4), indicate that at least in the case of isolated molecules the energy difference between an ee species and its isomer with both substituents in axial positions (aa) might be quite low (< 13 kJ mol-1).