Synthesis of 1-thioglycosides

Triflic acid-mediated synthesis of thioglycosides

An efficient synthesis of thioglycosides from per-acetates in the presence of triflic acid is described. The developed protocol features high reaction rates and product yields. Some reactive sugar series give high efficiency in the presence of sub-stoichiometric trifluoromethanesulfonic acid (TfOH) in contrast to other known protocols that require multiple equivalents of Lewis acids to reach high conversion rates.

The Ramberg–Bäcklund reaction for the synthesis of C-glycosides, C-linked-disaccharides and related compounds

The discovery of the Ramberg-Bäcklund procedure for preparing exo-glycals from S-glycoside dioxides, developed independently in (Old) York and New York, is reviewed. The methodology is successful with glucose, galactose, mannose, xylose, fucose, ribose, altrose, 2-deoxy-arabino-hexose (2-deoxy-glucose) and daunosamine derivatives, and has been used to prepare di-, tri- and tetra-substituted exo-glycals. More recent developments, such as one-pot variants, and protecting group-free procedures, are also covered. Synthetic applications of the exo-glycals, for example, to prepare beta-glycosidase inhibitors, spirocyclic glucose derivatives, beta-C-glycosides, C-glycosyl porphyrin glycoconjugates and C-glycosyl amino acids, are also discussed. Finally, applications of the Ramberg-Bäcklund process for the synthesis of known and novel C-glycosides, and in natural product synthesis, are reviewed.

Synthesis and antiangiogenic activity of exo -olefinated deoxoartemisinin derivatives

10-exo-Bromoalkylidene and benzylidene deoxoartemisinin derivatives with antiangiogenic activity were synthesized from corresponding 10-alkanesulfonyl dihydroartemisinin and 10-phenylmethanesulfonyl dihydroartemisinin using a highly efficient, mild, and simple Ramberg-Bäcklund rearrangement.

Efficient Synthesis of exo-Olefinated Deoxoartemisinin Derivatives by Ramberg−Bäcklund Rearrangement

10-exo-Bromoalkylidene- and benzylidenedeoxoartemisinins were synthesized from corresponding 10-alkanesulfonyldihydroartemisinin and 10-phenylmethanesulfonyldihydroartemisinin using a highly efficient, mild, and simple Ramberg-Bäcklund rearrangement.

A mild and convenient indium(III) chloride-catalyzed synthesis of thioglycosides

The efficiency of glycosidation reactions generally involves a high chemical yield, as well as high/complete stereo- and regioselectivity. All these depend on the compatibility of the reactivity of glycosyl donors and acceptors. Among glycosyl donors, thioglycosides are widely used because of their high degree of stability in many organic reactions. Although there are number of methods available for the preparation of thioglycosides, all of them have one or more disadvantages, especially concerning the time factor and cumbersome workup procedures. Here we report a convenient and high-yielding method for the preparation of thioglycosides.