Stereo-controlled approach to pyrrolidine iminosugar C-glycosides and 1,4-dideoxy-1,4-imino-l-allitol using a d-mannose-derived cyclic nitrone

Stereocontrolled total synthesis of iminosugar 1,4-dideoxy-1,4-imino-D-iditol

The first stereocontrolled total synthesis of iminosugar 1,4-dideoxy-1,4-imino-D-iditol is described. The key step in our approach was the double diastereoselection in the asymmetric dihydroxylation (AD) of suitable optically active olefin, the chiral vinyl azido alcohol 9. Performing the AD using the most common Cinchona alkaloids as ligands enabled us to identify the ligand of choice for the stereodivergent synthesis of 1,4-dideoxy-1,4-imino-D-iditol and 1,4-dideoxy-1,4-imino-D-galactitol. These type of iminosugars, both natural and unnatural, are intensively studied for their promising chemotherapeutic properties against viral infections, diabetes, cancer, and tuberculosis.

Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin-Anh and Chelation-Control Models

This review describes the additions of allylmagnesium reagents to carbonyl compounds and to imines, focusing on the differences in reactivity between allylmagnesium halides and other Grignard reagents. In many cases, allylmagnesium reagents either react with low stereoselectivity when other Grignard reagents react with high selectivity, or allylmagnesium reagents react with the opposite stereoselectivity. This review collects hundreds of examples, discusses the origins of stereoselectivities or the lack of stereoselectivity, and evaluates why selectivity may not occur and when it will likely occur.

Asymmetric routes toward polyhydroxylated pyrrolidines: Synthesis of 1,4-dideoxy-1,4-imino-d-galactitol and 1,4-dideoxy-1,4-imino-d-glucitol

Herein the total synthesis of the pyrrolidine alkaloids 1,4-dideoxy-1,4-imino-d-galactitol and its diastereoisomer 1,4-dideoxy-1,4-imino-d-glucitol is described, starting from a common optically active precursor. The key step in our approach was the double diastereoselection in the asymmetric dihydroxylation of chiral vinyl azido alcohols, obtained by means of two different regio- and stereoselective nucleophilic openings of the corresponding chiral vinyl epoxide.

Design, synthesis and bioactivity evaluation of Galf mimics as antitubercular agents

A series of novel Galf mimics has been synthesized and characterized by IR, (1)H NMR, (13)C NMR, mass spectral and element analysis. All the newly prepared compounds were screened for their antitubercular activities. Bioactivity assays manifested that most of Galf mimics exhibited good antitubercular activities. Especially compound 4d and 4e displayed remarkable antitubercular efficacies, which were comparable to ethambutol.

An efficient synthesis of aldohexose-derived piperidine nitrones: precursors of piperidine iminosugars

d-Glucopyranose-derived and l-idopyranose-derived piperidine nitrones were synthesized in good overall yields through six-step reaction sequence starting from readily available 2,3,4,6-tetra-O-benzyl-d-glucopyranose. The method is efficient and could be general for the synthesis of aldohexose-derived piperidine nitrones which are precursors of piperidine iminosugars.

Synthesis, computational study and glycosidase inhibitory activity of polyhydroxylated conidine alkaloids--a bicyclic iminosugar

New bicyclic conidine iminosugars 1d and 1e were synthesized from D-glucose. Thus, D-glucose was converted to sugar beta-amino acids 3a and 3b in good yields. Individual treatment of 3a/3b with the Mukaiyama reagent afforded sugar beta-lactams 4a/4b that on reduction with LiAlH(4)/AlCl(3) gave azetidines 5a/5b with a sugar appendage. Reductive aminocyclization of sugar azetidines 5a/5b afforded the corresponding conidine iminosugars 1d/1e. Based on the (1)H NMR and DFT calculation studies the conformation of 1d was assigned as half chair A2 and that of 1e as a boat B2. The glycosidase inhibitory activities of 1d and 1e such as alpha-mannosidase, alpha-glucosidase and alpha-galactosidase were studied. The alpha-amylase activity was compared with acarbose. Compound 1d was found to be a moderate inhibitor of glycosidases while 1e was noticed to be a good inhibitor of alpha-mannosidase and a moderate inhibitor of other glycosidases. These results were substantiated by molecular docking studies using WHAT IF software and the AUTODOCK 3.0 program.