This work reports stannous chloride (SnCl2)-catalyzed regio/site-selective acylation with unusually broad substrate scope. In addition to 1,2- and 1,3-diols and glycosides containing cis-vicinal diol, the substrate scope also includes glycosides...

An improved method to synthesize 1-glycosyl thioacetates was developed, where per-O-acetylated glycoses were allowed to directly react with potassium thioacetate (KSAc) in the presence of BF 3 • Et 2 O in ethyl acetate under mild conditions. This method not only overcomes the disadvantage of the traditional onestep method, which is that the odorous and toxic thioacetic acid has to be used, but also overcomes the disadvantage of the traditional two-step method, which is that the unstable intermediate, glycosyl halide, has to be synthesized from the per-O-acetylated glycose in advance. Based on this, the per-O-acetylated glucosyl disulfide and the per-O-acetylated glucosyl 1-thiol were efficiently synthesized in high yields (91 % and 90 % respectively) starting from per-O-acetylated glycoses in two-step without the need to isolate intermediate products.Through metal-catalyzed cross-coupling of per-O-acetylated glucosyl 1-thiol with aryl-iodide under very mild conditions, two thioglucoside gliflozin analogues were efficiently synthesized in high yields for the first time. These two thioglucoside gliflozin analogues were further confirmed to be stable to hydrolysis of β-glucosidase.

A relatively green method for synthesizing 1-thioalkyl glycosides has been developed, where sodium alkanethiolates were used to react with per-O-acetylated sugars instead of odorous alkyl mercaptans in the presence of BF3·Et2O without the use of solvents under mild conditions. Furthermore, we found that 1,2-trans-β-thioglycosides can be converted into corresponding 1,2-cis-α-thioglycosides in the presence of trifluoromethanesulfonic acid in nonpolar solvents under mild conditions. This provides a simple and efficient new approach for synthesizing challenging 1,2-cis-α-thioglycosides.

Based on SnCl2‐catalyzed acetalation and selective benzoylation, a one‐pot strategy to efficiently synthesize orthogonally protected glycosyl acceptors with 2‐OH/3‐OH was developed. Consequently, 2‐OBz or 3‐OBz 4,6‐O‐benzylidene galactosides and glucosides were efficiently prepared in moderate to high yields starting from free galactosides and glucosides, and were used as valuable glycosyl acceptors for the synthesis of blood group antigens O and B analogues in this study.

An improved method to efficiently synthesize 2-OH thioaryl glycosides starting from corresponding per-protected glycals was developed, where 1,2-anhydro sugars were prepared by the oxidation of glycals with oxone, followed by reaction of crude crystalline 1,2-anhydro sugars with NaBH4 and aryl disulfides. This method has been further used in a one-pot reaction to synthesize glycosyl donors having both “armed” and “NGP (neighboring group participation)” effects.