Synthesis of Kojitriose using Silicon-Tethered Glycosidation.
作者:Mikael Bols、Christian Orrenius、Niklas Öhrner、C. Rikard Unelius、Karl Hult、Torbjörn Norin、Muhammed Nour Homsi、Frank K. H. Kuske、Monika Haugg、Nathalie Trabesinger-Rüf、Elmar G. Weinhold
DOI:10.3891/acta.chem.scand.50-0931
日期:——
Reaction of 3,4,6-tri-O-acetyl-beta-D-glucopyranosyl chloride (1) with potassium phenylselenate gave phenyl 3,4,6-tri-O-acetyl-1-seleno-alpha,beta-D-glucopyranoside (2) in 59% yield. Silylation of benzyl 3,4,6-tri-O-benzyl-beta-D-glucopyranoside (4) with ethyl 3,4,6-tri-O-benzyl-2-O-chlorodimethylsilyl-1-thio-beta-D-glucopyranoside gave benzyl 2-O-(3,4,6-tri-O-benzyl-1-S-ethyl-1-thio-beta-D-glucopyranos-2-O-yldimethylsilyl)-3,4,6-tri-O-benzyl-beta-D-glucopyranoside (5) in 35% yield. Reaction of 5 with N-iodosuccinimide in nitromethane gave benzyl 2-O-(3,4,6-tri-O-benzyl-alpha-D-glucopyranosyl)-3,4,6-tri-O-benzyl-beta-D-glucopyranoside (6) in 45% yield. Chlorodimethylsilylation of phenyl 3,4,6-tri-O-acetyl-1-seleno-alpha-D-glucopyranoside (2 alpha) and reaction with 6 gave benzyl 2-O-[2-O-(3,4,6-tri-O-acetyl-1-Se-phenyl-1-seleno-alpha-D-glucopyranos-2-O-yldimethylsilyl) -3,4,6-tri-O-benzyl-alpha-D-glucopyranosyl]-3,4,6-tri-O-benzyl-beta-D-glucopyranoside (7) in 82% yield. Intramolecular glycosidation of 7 using N-iodosuccinimide in nitromethane gave benzyl 2-O-[2-O-(3,4,6-tri-O-acetyl-alpha-D-glucopyranosyl)-3,4,6-tri-O-benzyl-alpha-D-glucopyranosyl]-3,4,6-tri-O-benzyl-beta-D-glucopyranoside (8) in 45% yield. Deprotection of 8 gave kojitriose (9) in quantitative yield. Chlorodimethylsilylation of 1,3,4,6-tetra-O-benzyl-alpha,beta-D-fructofuranose (10) with dimethyldichlorosilane and pyridine followed by reaction with ethyl 3,4,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside (3) gave ethyl 2-O-(1,3,4,6-tetra-O-benzyl- alpha,beta-D-fructofuranosyloxydimethylsilyl)-3,4,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside (11) in 85% yield. Chlorodimethylsilylation of 1,3,4,6-tetra-O-benzoyl-alpha-D-fructofuranose (12) with dimethyldichlorosilane and triethylamine followed by reaction with phenyl 3,4,6-tri-O-acetyl-1-thio-alpha-D-glucopyranoside (13) gave phenyl 2-O-(1,3,4,6-tetra-O-benzoyl-alpha-D-fructofuranosyloxydimethylsilyl)-3,4,6-tri-O-acetyl-1-thio-alpha-D-glucopyranoside (14) in 62% yield. Both 11 and 14 failed to undergo intramolecular glycosidation.