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

trans-2-Phenyltetrahydropyran-3-ylmethyl p-toluene-sulfonate, C19H22O4 S, (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 su bstituents in (6) are oriented trans to each other and, as expected, o ccupy 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 di fference between an ee species and its isomer with both substituents i n axial positions (aa) might be quite low (< 13 kJ mol-1).