Synthesis Of α-(1â†'6)-S-Linked-glucans

A new simple method for the highly stereo selective synthesis of α-(1â†'6)-S-linked-glucans is described. Glycosylation of configurationally pure α-glucosyl thiol with6-deoxy-6-iodo-a-D-thioglycosides in the presence of phase transfer conditions, afforded α-(1â†'6)-S-linked-D-glucosinolate in excellent a-stereoselectivity and high yield. Subsequently our work is the achievement of α-(1â†'6)-S-linked-glucans through a similarly iterative assembly of carbohydrate units in excellent a-stereoselectivity.Chapter one is the preface, mainly introduces the natural carbohydrate material st-ructure and its characteristics which1,6-glucoside bond exists; Synthesis of α-(1â†'6)-g-lucans; Construction of (1â†'6)-thio-linked glycoside bond; Synthetic routes to a-glucos y1thiol and deoxyhalogeno sugars.Chapter two retrosynthetic analysis of α-(1â†'6)-S-linked-glucans was undertaken. The key is the synthesis of a-glucosyl thiol:ring-opening of1,6-anhydrosugars with c-ommercially available bis(trimethylsilyl)sulfide, and on the basis of this to get6-deoxy-6-iodo-a-D-thioglycosides. Then glycosylation of the a-glucosyl thiol with deoxyhaloge no sugars in a two-phase system in the presence of a phase transfer catalyst (PTC) le-d to the desired disaccharide part in excellent a-stereoselectivityChapter three introduces the synthesis of α-(1â†'6)-S-linked-glucans in detail, mai nly through a similarly iterative assembly of carbohydrate units.