Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

Addition of Lithiated 1,3-Dithiane and Nitronate to Sugar-Derived Imines: Synthesis of Homoiminosugars and Pipecolic Acid Analogues

The one-pot two-step stereoselective synthesis of 1,2-trans-1-C-1,3-dithian-2-yl and 1,2-cis-1-C-nitromethyl iminosugars from sugar lactams is disclosed, exploiting Schwartz's reagent triggered amide to imine reduction followed by Corey-Seebach or nitro-Mannich-mediated functionalizations. Processing of the dithiane moiety provided the naturally occurring β-HNJ and α-HMJ homoiminosugars, while processing of the nitromethyl group gave access to α-HNJ and pipecolic acid derivatives. Epimerization of this function was also successfully examined. Final hydrogenolysis furnished a set of known and new glycomimetics, amongst which two compounds displayed potent glycosidase inhibition.

Sugars in Multicomponent Reactions: A Toolbox for Diversity-Oriented Synthesis

Multicomponent reactions (MCRs) cover strategically employed chemical transformations that incorporate three or more reactants in one pot leading to a functionalized final product. Thus, it is an ideal tool to achieve high levels of complexity, diversity, yields of desired products, atom economy, and reduced reaction times. Sugars belong to the class of naturally occurring compounds with fascinating applications in the field of drug discovery due to the presence of various hydroxy groups and well-defined stereochemistry. However, their potential in MCRs has been realized only recently. This account describes recent advances in the synthesis of sugar-derived heterocycles synthesized by MCRs. We hope to encourage the synthetic and medicinal chemistry community to apply this powerful MCR chemistry to generate novel glycoconjugate challenges.

1 Introduction

2 Synthesis of Various Functionalized Sugar Compounds

2.1 Passerini and Ugi Multicomponent Reactions

2.2 Petasis Reaction

2.3 Hantzsch Reaction

2.4 Domino Ferrier–Povarov Reaction

2.5 Marckwald Reaction

2.6 Groebke–Blackburn–Bienaymé (GBB) Reaction

2.7 Prins–Ritter Reaction

2.8 Debus–Radziszewski Imidazole Synthesis Reaction

2.9 Mannich Reaction

2.10 A3-Coupling Reaction

2.11 [3+2]-Cycloaddition Reactions

2.12 Miscellaneous Reactions

3 Conclusion

The Ugi three-component reaction and its variants

A broad variety of α-aminoamide-based compounds have been synthesized via the three-component version of the Ugi reaction (U-3CR) or by any of its variants (Ugi-Zhu-3CR, Orru-3CR, Ugi-4C-3CR, Ugi-Joullié-3CR, GBB-3CR, Ugi-Reissert-3CR, and so on).