Facile method for trimethylsilylation of alcohols using hexamethyldisilazane and ammonium thiocyanate under neutral conditions

A highly efficient method for trimethylsilylation of primary, secondary, tertiary, allylic, and a variety of sugar-derived alcohols using hexamethyldisilazane in the presence of a catalytic amount of ammonium thiocyanate under neutral conditions is reported

The intramolecular conjugate addition of benzylamine to a D-glucose derived α,β-unsaturated ester: an efficient synthesis of trihydroxylated pyrrolidine alkaloids as potential glycosidase inhibitors

A short and efficient synthesis of 1,4,5-trideoxy-1,4-imino-l-xylo-hexitol 2a and 1,4,5-trideoxy-1,4-imino-D-arabino-hexitol 2b is reported using the intramolecular conjugate addition of in situ generated benzylamine to the α,β-unsaturated ester 4, derived from D-glucose, as the key step

Rhodium carbenoid induced [1, 2]-migration in L-lyxo-configurated α-diazo-β-keto ester: synthesis of a new griseolic acid analogue

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An efficient synthesis of D-erythro- and D-threo-sphingosine from D-glucose: olefin cross-metathesis approach

The D-erythro- and D-threo-sphingosine were synthesized via E-selective olefin cross-metathesis using a D-glucose-derived building block and long-chain terminal alkene

Synthesis of (-)-lentiginosine, its 8a-epimer and dihydroxylated pyrrolizidine alkaloid from D-glucose

The D-glucose derived α,β-unsaturated ester 5 on 1,2-acetonide deprotection; oxidative diol cleavage followed by treatment with N-benzylamine in the presence of NaBH3CN undergoes reductive amination; a concomitant intramolecular conjugate addition reaction leading to the formation of dihydroxypyrrolidine-ester 6a; monohydroxypyrrolidine-γ-lactone 6b. Intermediates 6a and 6b were efficiently converted to (−)-lentiginosine 3a, its 8a-epimer 3b, pyrrolizidine azasugar 4 in good overall yield

Efficient synthesis of (+)-1,8,8a-tri-epi-swainsonine, (+)-1,2-di-epi-lentiginosine, (+)-9a-epi-homocastanospermine and (-)-9-deoxy-9a-epi-homocastanospermine from a D-glucose-derived aziridine carboxylate, and study of their glycosidase inhibitory activities

The utility of a D-glucose-derived aziridine carboxylate was demonstrated for the synthesis of polyhydroxylated quinolizidine and indolizidine alkaloids. The chemoselective reduction of 1 followed by two-carbon homologation by the Wittig reaction afforded γ,δ-aziridino-α,β-unsaturated ester 9, which on regioselective nucleophilic aziridine ring opening either by using water as a nucleophile or hydrogenation afforded δ-lactams 11/16-true synthons for the synthesis of four structurally different iminosugars, namely quinolizidine alkaloids 5b/5c, swainsonine 6b and lentiginosine 7b analogues. Glycosidase inhibitory activities of these iminosugars were investigated

Divergent Synthesis of 4-<i>epi</i>-Fagomine, 3,4-Dihydroxypipecolic Acid, and a Dihydroxyindolizidine and Their β‑Galactosidase Inhibitory and Immunomodulatory Activities

A divergent asymmetric synthesis of the titled iminosugars has been formulated starting from a chiral homoallyl alcohol as the versatile intermediate. The homoallyl alcohol was prepared by a highly diastereoselective Barbier reaction on a d-glucose-derived aldehyde. The protection of its hydroxyl function followed by reductive ozonolysis of the olefin and a subsequent one-pot three-step protocol involving a Staudinger reaction, reductive amination, and benzyloxy carbonyl protection yielded an important bicyclic furanopiperidine derivative. This was converted to the target compounds by following standard reactions. Among the synthesized compounds, 4-<i>epi</i>-fagomine (<b>2b</b>) was the best β-galactosidase inhibitor, and it also prevented LPS-mediated activation of Raw 264.7 macrophage cells. Its congener, 3,4-dihydroxypipecolic acid (<b>4b</b>) also showed similar trends in its cytokine- and enzyme-inhibitory properties at a low concentration (10 μM) but was proinflammatory at higher concentrations. The bicyclic compound dihydroxyindolizidine (<b>21</b>) reduced the proinflammatory cytokine (IL-1β and TNF-α) levels in the LPS-activated Raw 264.7 cells without showing any enzyme-inhibition activity

Synthesis and glycosidase inhibitory studies of pentahydroxyindolizidines: D-glucose-derived aziridine-2-carboxylate approach

D-Glucose-derived aziridine-2-carboxylate 1 was converted into &#945;-amino aldehyde 7, which, after Wittig olefination, asymmetric dihydroxylation, hydrogenation followed by LiAlH<SUB>4</SUB> reduction, and N-Cbz protection, afforded two diastereomeric pyrrolidines 11a and 11b with sugar appendages. Removal of the 1,2-acetonide functionality in 11a/11b and reductive amination gave the pentahydroxyindolizidine alkaloids 6g and 6h, respectively, with (S) absolute configurations at the ring junctions. The glycosidase inhibitory activities of these compounds were studied