Arabinoamidine synthesis and its inhibition toward β-glucosidase (sweet almonds) in comparison to a library of galactonoamidines

Sugar-Derived Amidines and Congeners: Structures, Glycosidase Inhibition and Applications

Glycosidases, the enzymes responsible for the breakdown of glycoconjugates including di-, oligo- and polysaccharides are ubiquitous through all kingdoms of life. The extreme chemical stability of the glycosidic bond combined with the catalytic rates achieved by glycosidases makes them among the most proficient of all enzymes. 
 Given their multitude of roles in vivo, inhibition of these enzymes is highly attractive with potential in the treatment of a vast array of pathologies ranging from lysosomal storage and diabetes to viral infections. Therefore great efforts have been invested in the last three decades to design and synthesize inhibitors of glycosidases leading to a number of drugs currently on the market. Amongst the vast array of structures that have been disclosed, sugars incorporating an amidine moiety have been the focus of many research groups around the world because of their glycosidase transition state-like structure. In this review we report and discuss the structure, the inhibition profile and the use of these molecules including related structural congeners as transition state analogs.

Evaluating hydrophobic galactonoamidines as transition state analogs for enzymatic β-galactoside hydrolysis

A spectroscopic examination of six galactonoamidines with inhibition constants and efficacy in the low nanomolar concentration range (Ki = 6-11 nM, IC50 = 12-36 nM) suggested only two of them as putative transition state analogs for the hydrolysis of β-galactosides by β-galactosidase (A. oryzae). A rationale for the experimental results was elaborated using docking and molecular dynamics studies. An analysis of the combined observations reveals several common factors of the compounds suggested as transition state analogs (TSAs): the putative TSAs have a similar orientation in the active site; show conserved positioning of the glycon; display a large number of H-bond interactions toward the catalytically active amino acid residues via their glycon; and exhibit hydrophobic interactions at the outer rim of the active site with small changes of the position and orientation of their respective aglycons.

Diastereoselective Ritter-like Reaction on Cyclic Trifluoromethylated N,O-Acetals Derived from l-Tartaric Acid

Despite the presence of the highly electron-withdrawing fluorinated substituent, cyclic α-trifluoromethylated N-acyliminium ions were successfully generated from fluorinated O-acetyl-N,O-acetal l-tartaric acid derivatives. The addition of nitriles on these intermediates occurred with high to excellent syn diastereoselectivity and led, in most cases, to oxazolines and amides as single diastereomers. The diastereoselectivity of the addition and the nature of the reaction product depend on the substituents on the hydroxyl groups of the tartaric acid scaffold. This methodology gave access to enantiopure, highly functionalized 5-(trifluoromethyl)pyrrolidin-2-one derivatives, bearing the fluorinated substituent on a tetrasubstituted carbon.

Discrimination of chiral copper(ii) complexes upon binding of galactonoamidine ligands

Chiral binuclear Cu(ii) complexes are differentiated upon binding top-methylbenzyl-d-galactonoamidine. A sequential binding model is elaborated reflecting the altered coordination sites.