Synthesis of 3,6-O-(o-Xylylene)glucopyranosyl Fluoride, an Axial-Rich Glycosyl Donor of β-Glycosylation
摘要:
Despite the reported complete beta-selectivity in glycosylation with 2,4-di-O-benzyl-3,6-O-(o-xylylene)-glucopyranosyl fluoride, its preparation has been inefficient. This paper describes an improved route for the donor, including the formation of the 3,6-bridge on 1,2,4-orthoacetylglucose, the preparation of which was also refined, along with a discovered feature that the 3,6-bridged glucose prefers the furanose form. Although this feature made the synthesis of the desired glucopyranosyl donor difficult, application of thermal glycosylation solved the problem. With a modifiable intermediate, the improved availability of the donor would expand the applications.
Synthesis of 3,6-O-(o-Xylylene)glucopyranosyl Fluoride, an Axial-Rich Glycosyl Donor of β-Glycosylation
摘要:
Despite the reported complete beta-selectivity in glycosylation with 2,4-di-O-benzyl-3,6-O-(o-xylylene)-glucopyranosyl fluoride, its preparation has been inefficient. This paper describes an improved route for the donor, including the formation of the 3,6-bridge on 1,2,4-orthoacetylglucose, the preparation of which was also refined, along with a discovered feature that the 3,6-bridged glucose prefers the furanose form. Although this feature made the synthesis of the desired glucopyranosyl donor difficult, application of thermal glycosylation solved the problem. With a modifiable intermediate, the improved availability of the donor would expand the applications.
The first use of molecularsieves (MS) 5A as an acidic reagent is described. We observed the acidic property during a dehydration reaction of 2-methyl-4-phenyl-3-butyn-2-ol. The acidity was sufficient to introduce ethoxyethyl and methoxyisopropyl protecting groups into alcohols. Additionally, the employment of MS 5A improved the synthesis of 1,2,4-orthoacetyl-α-d-glucopyranose at the intramolecular
e possesses a skew-boat glucopyranose ring whose steric strain is expected to show high reactivity. This study describes the β-selective thioglycosylation of 1,2,4-O-orthoacetyl-α-d-glucose. Indium(III) bromide catalyzes the reaction in trifluoromethylbenzene at ambient temperature in the presence of molecular sieves 4A, resulting in the corresponding thioglycoside product with perfect β-selectivity
Despite the reported complete beta-selectivity in glycosylation with 2,4-di-O-benzyl-3,6-O-(o-xylylene)-glucopyranosyl fluoride, its preparation has been inefficient. This paper describes an improved route for the donor, including the formation of the 3,6-bridge on 1,2,4-orthoacetylglucose, the preparation of which was also refined, along with a discovered feature that the 3,6-bridged glucose prefers the furanose form. Although this feature made the synthesis of the desired glucopyranosyl donor difficult, application of thermal glycosylation solved the problem. With a modifiable intermediate, the improved availability of the donor would expand the applications.