Template-directed intramolecular C-glycosidation. cation-mediated synthesis of ketooxetanes from thioglycosides

Bicyclic ketooxetanes may be assembled using cation-mediated cyclisation reactions of thioglycosides possessing silyl enol ether-containing side-chains.     

An olefin cross metathesis approach to C-disaccharide analogs of the α-d-arabinofuranosyl-(1→5)-α-d-arabinofuranoside motif found in the mycobacterial cell wall

Reported is the synthesis of a C-disaccharide analog of the α-d-Araf-(1→5)-α-d-Araf motif present in the cell wall of mycobacteria, including the human pathogen Mycobacterium tuberculosis. The key step is an olefin cross metathesis reaction that proceeds in excellent yield and which can be carried out on mmol scale.     

Hydrolytically stable arabinofuranoside analogs for the synthesis of arabinosyltransferase inhibitors

The first members of two new families of arabinosyltransferase inhibitors, derived from previously reported hybrid compounds covalently associating an iminoalditol with an α-d-arabinofuranoside, have been prepared. In place of the arabinofuranoside moiety, they incorporate in their structure a suitably substituted tetrahydrofuran (C-glycoside family) or a cyclopentane (carba-sugar family) for mimicking the α-d-arabinofuranoside ring.     

Improved synthesis of the C-glucuronide/glycoside of 4-hydroxybenzylretinone (4-HBR)

Improvements in the synthesis of carbon-linked glucuronide/glucoside conjugates of cancer chemopreventive retinoids have been achieved starting with 2,3,4,6-tetra-O-benzyl-D-glucopyranose. The revised approach demonstrates better yields, eliminates the use of an expensive, carcinogenic protecting group reagent, and avoids much painstaking chromatography. The new approach should allow synthesis of larger quantities of the agents for detailed animal and mechanistic studies.     

Versatile Glycosyl Sulfonates in β-Selective C-Glycosylation

C-Glycosides are both a common motif in many bioactive natural products and important glycoside mimetics. We demonstrate that activating a hemiacetal with a sulfonyl chloride, followed by treating the resultant glycosyl sulfonate with an enolate results in the stereospecific construction of β-linked C-glycosides. This reaction tolerates a range of acceptors and donors, including disaccharides. The resulting products can be readily derivatized into C-glycoside analogues of β-glycoconjugates, including C-disaccharide mimetics.     

The Copper Halide-Catalyzed Mono-Substitution of Bromine in α,-dibromoalkanes by Grignard reagents. A Reinvestigation

α,ω-Dibromoalkanes have been converted into mono-bromides R(CH₂)_nBr by reaction with the Grignard compounds RMgBr in THF in the presence of 5 mol % of copper(I)bromide. In contrast to what is suggested in the original literature, this method has a limited scope.