MOLECULAR AND CRYSTAL-STRUCTURES OF 2,3,4,6,1',3',4',6'-OCTA-O-ACETYL-BETA-SOPHOROSE, METHYL 2,3,4,6,3',4',6'-HEPTA-O-ACETYL-BETA-SOPHOROSIDE, AND METHYL 2,3,4,6,3',4'-HEXA-O-ACETYL-6'-DEOXY-BETA-SOPHOROSIDE

The molecular and crystal structures of 2,3,4,6,1',3',4',6'-octa-O-acetyl-beta-sophorose (beta-sophorose octaacetate), methyl 2,3,4,6,3',4',6'-hepta-O-acetyl-beta-sophoroside (methyl beta-sophoroside heptaacetate), and methyl 2,3,4,6,3',4'-hexa-O-acetyl-6'-deoxy-beta-sophoroside (methyl 6'-deoxy-beta-sophoroside hexaacetate) were determined by X-ray diffraction. All structures were obtained by the direct method and refined by the full-matrix least-squares procedure. The crystal data and final R values are as follows: beta-sophorose octaacetate, C28O19H38, monoclinic, P2(1), a = 15.529(4), b = 10.958(2), c = 10.804(2) Angstrom, beta = 107.73(3)degrees, D-obsd = 1.285 g cm(-3), D-calcd = 1.288 g cm(-3), Z = 2, R = 0.052, R(w) = 0.052; methyl beta-sophoroside heptaacetate, C27O18H38, orthorhombic, P2(1)2(1)2(1), a = 20.992(5), b = 27.642(7), c = 5.730(2)Angstrom D-obsd = 1.305 g cm(-3) = 1.295 g cm(-3), Z = 4, R = 0.064, R(w) = 0.066; methyl 6'-deoxy-beta-sophoroside hexaacetate, C25O16H36, hexagonal, P6(5), a = b = 15.136(2), c = 23.534(4)Angstrom, D-calcd = 1.264 g cm(-3) Z = 6, R = 0.079, R(w) = 0.064. All the D-glucose residues have the C-4(1) PYranose conformation. These three molecules interact with their surrounding molecules by van der Waals forces, only. Conformational angles of phi and psi at the beta (1 --> 2) glycosidic Linkage of these compounds are similar to each other and close to the energetically minimum positions. AU the primary acetate substituents at C-6 take a gauche-gauche conformation.