Three different fluoro- or chloro-substituted 1′-deoxy-1′-phenyl-β-D-ribofuranoses

Abstract

Crystal structures are reported for three fluoro- or chloro-substituted 1′-deoxy-1′-phenyl-β-D-ribofuranoses, namely 1′-deoxy-1′-(2,4,5-trifluorophenyl)-β-D-ribofuranose, C11H11F3O4, (I), 1′-deoxy-1′-(2,4,6-trifluorophenyl)-β-D-ribofuranose, C11H11F3O4, (II), and 1′-(4-chlorophenyl)-1′-deoxy-β-D-ribofuranose, C11H13ClO4, (III). The five-membered furanose ring of the three compounds has a conformation between a C2′-endo,C3′-exotwist and a C2′-endoenvelope. The ribofuranose groups of (I) and (III) are connected by intermolecular O—H...O hydrogen bonds to six symmetry-related molecules to form double layers, while the ribofuranose group of (II) is connected by O—H...O hydrogen bonds to four symmetry-related molecules to form single layers. The O...O contact distance of the O—H...O hydrogen bonds ranges from 2.7172 (15) to 2.8895 (19) Å. Neighbouring double layers of (I) are connected by a very weak intermolecular C—F...π contact. The layers of (II) are connected by one C—H...O and two C—H...F contacts, while the double layers of (III) are connected by a C—H...Cl contact. The conformations of the molecules are compared with those of seven related molecules. The orientation of the benzene ring is coplanar with the H—C1′ bond or bisecting the H—C1′—C2′ angle, or intermediate between these positions. The orientation of the benzene ring is independent of the substitution pattern of the ring and depends mainly on crystal-packing effects.