Several glucosides were prepared in good yields from 2,3,4,6-tetra-o -benzyl-α-d-glucopyranosyl dimethylphosphinothioate and alcohols in the presence of silver perchlorate. By this method α-glucosides were predominantly obtained.
Several glycopyranosyl dimethylphosphinothioates having a nonparticipating group at the C-2 position could be easily prepared by reactions of the corresponding glycopyranose and dimethylphosphinothioyl chloride using butyllithium as a base in tetrahydrofuran. These dimethylphosphinothioates are stable at room temperature and gave the corresponding α-glycosides, predominantly in good yields, by reactions with alcohols using silver perchlorate as an activator in the presence of molecular seives 4A in benzene at room temperature. Also, the combined use of iodine and a catalytic amount of triphenylmethyl perchlorate was effective for this glycosidation as a new activating system instead of silver perchlorate. Further, the synthetic intermediates of H-disaccharide and the Lewis X antigen were prepared using the present method.
An algorithm for the exhaustive enumeration of all possible unique substructures from a structural formula is described. The algorithm has been implemented in a computer program called GROWSUB. The program allows the chemist to specify his definition of the substructures with a choice of graph theoretical expressions: simple graph, node(atom) weighted, or node(atom) and edge(bond) weighted one. An illustrative example using acesulfame is discussed to describe the program, and applicabilities of the program are mentioned briefly.
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