Application of Carbohydrates with Methylene or Vinyl Groups in Heck–Mizoroki Cross-Coupling Reactions with O-Heterocycles

Structurally novel carbohydrate–O-heterocycle derivatives linked by various unsaturated carbon bridges were synthesized by palladium-catalyzed cross-coupling reactions

Photoinitiated Thiol-Ene Reactions of Various 2,3-Unsaturated O-,C- S- and N-Glycosides – Scope and Limitations Study

The photoinitiated thiol-ene addition reaction is a highly stereo- and regioselective, and environmentally friendly reaction proceeding under mild conditions, hence it is ideally suited for the synthesis of carbohydrate mimetics. A comprehensive study on UV-light-induced reactions of 2,3- unsaturated O-, C-, S- and N-glycosides with various thiols was performed. The effect of experimental parameters and structural variations of the alkenes and thiols on the efficacy and regio- and stereoselectivity of the reactions was systematically studied and optimized. The type of anomeric heteroatom was found to profoundly affect the reactivity of 2,3-unsaturated sugars in the thiol-ene couplings. Hydrothiolation of 2,3-dideoxy O-glycosyl enosides efficiently produced the axially C2-S-substituted addition products with high to complete regioselectivity. Moderate efficacy and varying regio- and stereoselectivity were observed with 2,3- unsaturated N-glycosides and no addition occurred onto the endocyclic double bond of C-glycosides. Upon hydrothiolation of 2,3-unsaturated S-glycosides, the addition of thiyl radicals was followed by elimination of the thiyl aglycone resulting in 3-S-substituted glycals

Short synthesis of idraparinux by applying a 2-O-methyl-4,6-O-arylmethylene thioidoside as a 1,2-trans α-selective glycosyl donor

The fully O-sulfated, O-methylated, heparin-related anticoagulant pentasaccharide idraparinux was prepared by a new synthetic pathway in 38 steps using D-glucose and methyl α-D-glucopyranoside as starting materials, with 23 steps for the longest linear route. The L-idose-containing GH fragment was obtained by a short and straightforward synthesis whereby a 4,6-cyclic-acetal-protected L-idosyl thioglycoside bearing a C2-nonparticipating group was used as the α-selective glycosyl donor. The novel L-idose donor was prepared with high chemo- and stereoselectivity by hydroboration–oxidation-based C5 epimerization starting from an orthogonally protected α-thioglucoside. The assembly of the pentasaccharide backbone was achieved by an F+GH and DE+FGH coupling sequence with full stereoselectivity in each glycosylation step

A low-temperature, photoinduced thiol-ene click reaction: a mild and efficient method for the synthesis of sugar-modified nucleosides

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Photoinitiated Thiol-Ene Reactions of Various 2,3-Unsaturated O-, C- S- and N-Glycosides: scope and Limitations Study

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