STEREOCHEMICAL INVESTIGATION OF 2,3,4,6-TETRA-O-ACETYL-1-S-BENZHYDROXIMOYL-ALPHA-D-GLUCOPYRANOSE

2,3,4,6-Tetra-0-acetyl-1-S-benzhydrox-imoyl-1-thio-alpha-D-glucopyranose (alpha-GSL) is the first synthetic alpha-glucosinolate. C21H25NO10S, M(r) = 483.5, monoclinic, C2, a = 16247 (9), b = 11.182 (7), c = 13.420 (6) angstrom, beta = 91.62-(4)-degrees, V = 2437.33 angstrom3, Z = 4, D(m) = 1.309, D(x) = 1.317 Mg m-3, lambda(Mo Kalpha) = 0. 711 angstrom, F(000) = 1016, room temperature, final R = 0.052 for 3712 unique reflections. The stereochemistry around the C=N bond was determined. The glucose residue has the expected C-4(1) conformation and the hydroxyl group on the N atom is found to be syn to the sugar ring. The crystal structure is stabilized by packing interactions. The structural features at the glucosidic position are: C(1)-S = 1.838 (3), C(7) = N = 1.273 (5) angstrom, phi [0(5)-(l)-S-C(7)] = 54.9, psi [C(1)-S-C(7)-C(8)] = 42, C(1)-S-C(7) = 98.5 (2)-degrees. The observed conformational behaviour has been analyzed and compared with other known structures of thiosugars.