Regio- and stereo-controlled synthesis of β-Xyl(1–4)Rbo-5P1-Rbo, the partial structure of O-mannosyl glycan

Chemical and Chemo-Enzymatic Syntheses of Glycans Containing Ribitol Phosphate Scaffolding of Matriglycan

“…5- O -Allyl-2,3-di- O -benzyl-1- O - tert -butyldiphenylsilyl- d -ribitol ( 12 ) was benzylated with benzyl 2,2,2-trichloroacetimidate and trimethylsilyl trifluoromethanesulfonate (TMSOTf) in CH 2 Cl 2 at −20 to 7 °C to give 13 in 77% yield. The allyl group of 13 was isomerized in the presence of an iridium complex, and the vinyl ether obtained was removed with I 2 to give 14 in 71% yield.…”

“…We also speculate that 7 had higher reactivity than triacetate (10) positions were then benzylidenated with PhCH(OMe) 2 in the presence of p-toluenesulfonic acid (p-TsOH) in tetrahydrofuran (THF) to afford 9 in 78% yield in 2 steps. 12 was benzylated with benzyl 2,2,2-trichloroacetimidate and trimethylsilyl trifluoromethanesulfonate (TMSOTf) in CH 2 Cl 2 at −20 to 7 °C to give 13 in 77% yield. The allyl group of 13 was isomerized in the presence of an iridium complex, and the vinyl ether obtained was removed with I 2 to give 14 in 71% yield.…”

“…However, the underlying molecular mechanisms remain unclear because a sufficient amount of the core M3 OMG cannot be purified from natural sources. To overcome this issue, our group has already successfully synthesized some of the pivotal structures of the core M3 OMG: Xylβ1-4Rbo, 12 Xylβ1-4Rbo5P, 12 Xylβ1-4Rbo5P-1Rbo, 12 Xylα1-3GlcAβ1-4Xylβ1-4Rbo5P, 13 and Xylα1-3GlcAβ and the dimer, 13 in order to identify the reported structures. As an extension of our series of studies, we herein report the chemical synthesis of the oligosaccharide series containing Rbo5P: Rbo5P-3GalNAcβ1-OC 2 H 4 NHAc (1), Rbo5P-1Rbo5P-3GalNAcβ1-OC 2 H 4 NHAc (5), and Xylβ1-4Rbo5P-1Rbo5P-3GalNAcβ1-OC 2 H 4 NHAc (6), in regio-and stereo-controlled manners (Figure 2).…”

Stereo- and Regioselective Synthesis of O-Mannosyl Glycan Containing Matriglycan and a Part of Tandem Ribitol Phosphate

“…On the other hand, the linkage region of the O-mannosyl glycan with the ribitol residue was synthesized as shown in Scheme 6. The levulinoyl group of the previously synthesized xylosyl ribitol derivative (24) 26 was chemoselectively removed with hydrazine acetate to give the desired disaccharide (25) with triol on the xylosyl residue in 75% yield. Isopropylidene formation at the 2-and 3-positions of xylose of 25 was performed with 2-methoxypropene in the presence of camphorsulfonic acid in dimethylformamide (DMF) 25 The coupling of 21 and 26 was similarly achieved as the synthesis of 23 in a regio-and stereocontrolled manner (Scheme 7).…”

“…H 2 NNH 2 ·AcOH (112 mg) was added to a solution of 24 (274 mg, 252 μmol) in toluene (6.0 mL) and EtOH (3.0 mL) with stirring overnight. Volatiles were removed under diminished pressure.…”