(1S,2R,2 ' S)- and (1S,2S,2 ' S)-1-phenyl-2-phenylthio-2-(tetrahydropyran-2 '-yl-thio)ethanol diastereoisomers at 193 K

In the synthesis of 1-phenyl-2-phenylthio-2-(tetrahydropyran-2-ylthio)ethan ol, C19H22O2S2, four diastereoisomers are formed. Two non-centrosymmetric e nantiomeric forms which crystallize in space groups P2(1)2(1)2(1) and Pna2( 1) are presented. The former has an intramolecular hydrogen bond between th e hydroxyl group and the O atom of the tetrahydropyran ring. In the latter isomer, the hydroxyl group forms an intermolecular hydrogen bond to the O a tom of the tetrahydropyranyl group of a neighbouring molecule, joining the molecules into chains in the c-axis direction; the O . . .O distances are 2 .962 (4) and 2.764 (3) Angstrom, respectively. The tetrahydropyran rings ar e in chair conformations in both isomers and the S side chain has an equato rial orientation in the former, but an axial orientation in the latter mole cule.