Synthesis of trehazolin beta-anomer

Potential trehalase inhibitors: syntheses of trehazolin and its analogues

Trehazolin is a natural pseudodisaccharide obtained from Micromonospora strain SANK 62390 and Amycolaptosis trehalostatica, and later on it was found to be widely distributed in microorganisms, insects, plants, and animals. It has received much attention because of its importance as an inhibitor of the enzyme trehalase. This article is focused on the synthesis of natural trehazolin and its analogues, with details of the synthetic methods. Sufficient information is given to permit the selection of a suitable synthetic route for trehazolin and/or its analogues. Various approaches are provided for the synthesis of natural trehazolin and its analogues in a way that enables the researcher to decide whether to use a certain procedure, modify it, or propose a new synthetic methodology.

Synthesis and Evaluation of Isourea-Type Glycomimetics Related to the Indolizidine and Trehazolin Glycosidase Inhibitor Families

A practical synthesis of reducing isourea-derived azasugar glycomimetics related to the indolizidine and trehazolin glycosidase inhibitor families with different pK(a) values is disclosed. The polyhydroxylated bicyclic system was built from readily accessible hexofuranose derivatives through a synthetic scheme that involves the preparation of a 5-deoxy-5-carbodiimido adduct by triphenylphosphine-mediated tandem Staudinger--aza-Wittig-type coupling of azide and isothiocyanate precursors, intramolecular cyclization of a transient vic-hydroxycarbodiimide derivative, and nucleophilic addition of the endocyclic nitrogen atom of the generated 2-amino-2-oxazoline intermediate, with a pseudo-C-nucleoside structure, to the masked aldehyde group of the monosaccharide. The last step is pH-dependent so that the final compounds can pivot between the furanose and the 2-oxaindolizidine forms. Nevertheless, the indolizidine tautomer having the R configuration at the aminoacetalic center, fitting the anomeric effect, was the only species detected in solution at neutral or slightly acidic pH when starting from solutions at basic pH. Glycosidase inhibition tests (K(i) values down to 1.9 microM) showed a marked dependence of the selectivity and potency toward alpha- and beta-glucosidases upon the nature of the substituent at the exocyclic isourea nitrogen, shifting from alpha- to beta-selectivity when going from hydrophilic to hydrophobic substituents. Enzyme inhibition is also pH dependent, supporting a dominant role for the uncharged form of the polyhydroxyiminoindolizidine system in the inhibition of beta-glucosidases.

A Highly Efficient Pinacol Coupling Approach to Trehazolamine Starting from D-Glucose

A short and very efficient synthesis of trehazolamine (3), the aglycon of the potent trehalase inhibitor trehazolin (2), has been achieved starting from D-glucose. The key transformation in this approach is a high-yielding two-step, one-pot sequence consisting of a Swern oxidation of a 1,5-diol followed by a reductive carbocyclization of the resultant 1,5-dicarbonyl compound promoted by samarium diiodide. The overall yield of 3 is 39% over nine steps from 2,3,4,6-tetra-O-benzyl-D-glucose (5). An even shorter synthesis of 30, a diastereoisomeric analogue of 3, is also described starting from 5. The key transformation in this second route is a highly stereoselective ketone oxime ether reductive carbocyclization promoted also by samarium diiodide. The overall yield of 30 is 57% over four steps from 5.