RECENT PROGRESS IN O-GLYCOSIDE SYNTHESIS - METHODOLOGICAL ASPECTS

The present article deals with a short review on the recent methodological progress in O-glycoside synthesis. Particular stress is laid on the design of newer classes of glycosyl donor, which allow the selective activation/O-glycoside formation under specific reaction conditions. Based on the anomeric leaving group, glycosyl donors are classified into nine classes, 1) fluoride, 2) thioglycoside, 3) 0-acylate, 4) O- and S-carbonate derivatives, 5) phosphate derivatives, 6) trichloroacetimidate, 7) 1-hydroxyl sugar, 8) 4-pentenyl glycoside, 9) glycal, and their selective activation methods are tabulated. Also described are the other approaches based on different principles, e.g., glycosylidene carbene, anomeric O-alkylation, internal cyclization or glycoside synthesis based on physical means ; light, electric, thermal, and high pressure. Recent topics in this field are also included, 1) new protecting groups, 2) stereochemical control in manno- and 2-deoxy-sugars, and 3) the armed/disarmed concept,