Design and synthesis of 2-acetamidomethyl derivatives of isofagomine as potential inhibitors of human lysosomal β-hexosaminidases

Simple Synthesis of 1,2-Dideoxy-2-Vinyl Carbohydrates by Tin-Free Radical Reactions of Xanthates

Vinyl-substituted carbohydrates have been synthesized from glycals derived from hexoses and pentoses. Key step is the radical reaction of xanthates in the presence of triethylborane, a non-toxic reagent. The mechanism has been investigated by isolation of various side products, which speak for a reversibility of the cyclopropylmethyl radical ring-opening. Compared to reactions with tributyltin hydride, higher regioselectivities in favor of the 2-vinyl-substituted sugars have been obtained. Yields are slightly lower with triethylborane, but all products have been isolated in analytically pure form. The new reaction is applicable to benzyl- and silyl-protected carbohydrates, which makes free sugars accessible as well. Overall, more than 15 1,2-dideoxy-2-vinyl carbohydrates have been synthesized from simple precursors in only few steps.

Contributing to the Study of Enzymatic and Chemical Glycosyl Transfer Through the Observation and Mimicry of Glycosyl Cations

This account describes our efforts dedicated to: 1) the design of glycomimetics aimed at targeting therapeutically relevant carbohydrate processing enzymes, and 2) the observation, characterization, and exploitation of glycosyl cations as a tool for studying the glycosylation reaction. These findings have brought important data regarding this key ionic species as well as innovative strategies to access iminosugars of interest.

1 Introduction

2 The Glycosyl Cation, A Central Species in Glycosciences

2.1 A Selection of the Strategies Developed so far to Gain Insights into Glycosyl Cations Structure

2.2 When Superacids Meet Carbohydrates

3 Chemical Probes to Gain Insights into the Pseudorotational Itinerary of Glycosides During Glycosidic Bond Hydrolysis

3.1 Conformationally Locked Glycosides

3.1.1 The Xylopyranose Case

3.1.2 The Mannopyranose Case

3.2 Conformationally Flexible Iminosugars

3.2.1 Nojirimycin Ring Homologues

3.2.2 Noeuromycin Ring Homologues

3.2.3 Seven-Membered Iminosugar C-Glycosides

4 N-Acetyl-d-glucosamine Mimics

5 Ring Contraction: A Useful Tool to Increase Iminosugar’s Structural Diversity

6 Regioselective Deprotection of Iminosugar C-Glycosides to Introduce Diversity at C2 Position

7 Conclusion

Amino-functionalized iminocyclitols: synthetic glycomimetics of medicinal interest

A review on the syntheses and biological activities of unnatural glycomimetics highlighting the effect of replacement of hydroxyl groups of natural iminosugars by amino functionalities is presented.

Modifying the phenyl group of PUGNAc: reactivity tuning to deliver selective inhibitors for N-acetyl-d-glucosaminidases

The synthesis of analogues of the potentN-acetylhexosamindase inhibitor PUGNAc are described and were found to vary in both potency and selectivity against a set of biologically importantN-acetyl-d-glucosaminidases.

A divergent synthesis of 2-acyl derivatives of PUGNAc yields selective inhibitors of O-GlcNAcase

A divergent route facilitating the rapid synthesis of a series of O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenylcarbamate (PUGNAc)-based inhibitors, bearing different N-acyl groups has been developed. All compounds of this series are inhibitors of both human O-GlcNAcase and human beta-hexosaminidase, yet some effectively exploit differences between the active site architectures of these two human enzymes which render them selective for O-GlcNAcase. Such inhibitors may be valuable tools in dissecting the role of the O-GlcNAc post-translational modification at the cellular and organismal level since these compounds may have different pharmacokinetic properties when compared to other inhibitors of beta-N-acetyl-glucosaminidases.

Asymmetrized tris(hydroxymethyl)methane as a precursor of N- and O-containing 6-membered heterocycles through ring-closing metathesis

A novel synthetic application of asymmetrized tris(hydroxymethyl)methane (THYM), obtained in both enantiomeric forms in high e.e. via a chemoenzymatic procedure, is described. Starting from the common precursor , N- and O-containing 6-membered heterocycles have been prepared exploiting ring-closing metathesis as the key step. Possible elaborations of the double bond in and have been explored and, in the case of , conversion into the glycosidase inhibitor isofagomine has been achieved.