One-Pot Stereoselective Synthesis of Different Fused Multicyclic Iminosugars Based on the Iminium-lon Intermediate

Different novel fused multicyclic iminosugars were synthesized from D-ribose tosylate,aniline and vinyl ethyl ether by one-pot three-component stereoselective[4+2]reaction at different temperatures.The iminium-ion is the key intermediate for the reaction.As a result,several complex fused iminosugars 3a were obtained by aza-Diels-Alder mechanism at 60℃,while a series of aza-C-glycosides 5a were prepared by Mannich reaction at room temperature accompanied by another tetrahydroquinoline-fused iminosugars 4a(tricyclic derivatives)through aza-Diels-Alder cycloaddition.This strategy will help to construct structurally diverse and bioactive iminosugar analogues.

An Efficient and Simple Method for Stereoselective Synthesis of N-Substituted Iminosugars from D-Xylose Derivative

A series of new N-substituted iminosugars were successfully synthesized through a general synthetic route from D-xylose derivative.This approach provided a convenient access to the synthesis of N-alkylated iminosugars as po-tential glucosidase inhibitors,which included a reaction of reductive amination.Various N-alkylated iminosugars were prepared in good yields with high stereoselectivity.

Practical and concise synthesis of 2-oxo-3,4,5,6-tetraethoxyazepane from D-glucono-1,5-lactone

2-Oxo-3R,4S,5S,6S-tetraethoxyazepane was conveniently synthesized from D-glucono-1, 5-1actone with a yield of 10% overall. The key step of synthetic route-reductive 1,6-cyclization was completed efficiently by using Ph3P to give the expected lactam.

Inhibition of α-glucosidase activity by N-deoxynojirimycin analogs in several insect phloem sap feeders

Secondary metabolites and synthetic iminosugars that structurally resemble monosaccharides are potent inhibitors of a-glucosidase activity. The enzyme is core in cleaving sucrose in phloem feeding insects and it also plays a crucial role of reducing osmotic stress via the formation of oligosaccharides. Inhibition of hydrolysis by iminosug- ars should result in nutritional deficiencies and/or disruption of normal osmoregulation. Deoxynojirimycin （DNJ） and 2 N-alkylated analogs [N-butyl DNJ （NB-DNJ） and N-nonyl DNJ （NN-DNJ）] were the major iminosugars used throughout the study. The extensive experiments conducted with a-glucosidase of the whitefly Bemisia tabaci indicated the competitive nature of inhibition and that the hydrophilic DNJ is a potent inhibitor in com- parison to the more hydrophobic NB-DNJ and NN-DNJ compounds. The same inhibitory pattern was observed with the psyllid Cacopsylla bidens a-glucosidase. In contrast to the above pattern, enzymes of the aphids, Myzus persicae and Aphis gossypii were more sen- sitive to the hydrophobic iminosugars as compared to DNJ. In vivo experiments in which adult B. tabaci were fed dietary iminosugars, show that the hydrophilic DNJ was far less toxic than the lipophilic NB-DNJ and NN-DNJ. It is proposed that this pattern is attributed to the better accessibility of the hydrophobic NN-DNJ to the a-glucosidase membrane- bound compartment in the midgut. Based on the inhibitory effects of certain polyhydroxy N-alkylated iminosugars, a-glucosidase of phloem feeding hemipterans could serve as an attractive target site for developing novel pest control agents.

Synthesis of a novel C-branched polyhydroxylated cyclic nitrone

A novel C-branched polyhydroxylated cyclic nitrone 25.which could be a valuable intermediate for the synthesis of C-branched pyrrolidine iminosugars,was synthesized starting from the commercially available i.-arabinose in 29.0%total yield.

Synthesis of Iminosugar-Containing KRN7000 Analogues

Three new iminosugar-containing KRN7000 （also referred to as α-GalCer） analogues were designed and syn- thesized. In the design, the galactose moiety of KRN7000 was replaced by iminosugars and the iminosugar struc- tures were connected with ceramide in different manners with a C-glycosidic bond instead of the O-glycosidic bond. To our knowledge, this is the first report in which iminosugars are incorporated in KRN7000 structure modifica- tions. The synthetic compounds were evaluated for their ability to stimulate cytokine release. The results may benefit better understanding of structure-activity relationships and facilitate future design of more KRNT000 derivatives.