p-Cresyl 2,3-anhydro-5-deoxy-5-phthalimido-1-thio-alpha-D-lyxofuranoside

The crystal structure of the title compound, C20H17NO4S, (I), was determine d in order to compare the solution and solid-state conformations. The molec ule was synthesized as a building block for incorporation into oligosacchar ides comprised of conformationally restricted furanose residues. The furano se ring adopts an envelope conformation with the ring O atom displaced abov e the plane (an E-o conformation). The pseudorotational phase angle (P) is 88.6 degrees and the puckering amplitude (tau(m)) is 31.5 degrees. The C-2- C-1-S-C(Ph) torsion angle is - 163.2 (2)degrees, which places the aglycone in the exo-anomeric effect preferred position. The C1-S-C14 bond angle is 9 9.02 (13)degrees and the plane of the cresyl moiety is oriented nearly para llel to the four in-plane atoms of the furanose ring envelope. The orientat ion about the C4-C5 bond is gauche-gauche [Bock & Duus (1994). J. Carbohydr . Chem. 13, 513-543].