Allyl 4,6-O-benzylidene-1-β-D-glucopyranoside

Allyl 4,6-O-benzylidene-1-β-D-glucopyranoside Allyl 4,6-O-benzylidene-1-β-D-glucopyranoside is a protected carbohydrate derivative used as a key intermediate in stereoselective glycosylation and oligosaccharide synthesis. Its structure combines an allyl group at the anomeric position with a benzylidene acetal protecting the 4,6-hydroxyl groups, enabling precise functionalization of the glucopyranoside ring. Chemical Identity Molecular Formula : C₁₆H₂₀O₆ Molecular Weight : 308.32 g/mol Protection Groups : Benzylidene acetal (4,6-O), allyl ether (anomeric position) Synthesis The compound is synthesized from 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide via mercury-mediated allylation, followed by benzylidene acetal formation. Key steps include: Regioselective Protection : THF solvent promotes C-2 benzylation in α-anomers, while β-anomers (like this compound) form stable intermediates due to reduced steric hindrance. Crystallization : Purification often avoids chromatography, leveraging crystallization from solvents like methanol. Structural Features Benzylidene Acetal : Locks the 4,6-hydroxyls in a rigid bicyclic structure, leaving 2- and 3-positions reactive for further modifications. Allyl Group : Enhances stability and serves as a glycosyl donor in coupling reactions. The β-configuration at the anomeric center ensures stereochemical control during glycosidic bond formation. Applications Glycosylation : Used in TMSOTf-mediated reactions to construct α-linked disaccharides (e.g., α-D-Gal-(1→2)-D-Glc) with high stereoselectivity. Intermediate for Glycolipids : Derivatives like 2-O-allyl-3,4,6-tri-O-benzyl-D-glucopyranose are precursors for bacterial membrane glycolipids. Chiral Building Block : Facilitates synthesis of complex sugars and pharmaceutical intermediates. Reactivity and Functionalization The allyl group can undergo ozonolysis or hydrogenation for deprotection. Selective deprotection of the benzylidene acetal (e.g., using acidic conditions) regenerates 4,6-hydroxyls for further derivatization This compound's strategic protection pattern and stereochemical integrity make it invaluable in carbohydrate chemistry for targeted synthesis of bioactive molecules. Citations: https://www.beilstein-journals.org/bjoc/articles/3/26 https://www.chemicalbook.com/ChemicalProductProperty_EN_CB7209242.htm https://www.taylorfrancis.com/chapters/synthesis-4-6-benzylidene-acetals-methyl-glucopyranoside-ethyl-1-thio-gluco-galactopyranoside-gijsbert-van-der-marel-jeroen-codee/10.1201/b16602-26 https://pubchem.ncbi.nlm.nih.gov/compound/4_6-O-Benzylidene-D-glucopyranose https://pubmed.ncbi.nlm.nih.gov/963695/ https://pubmed.ncbi.nlm.nih.gov/21550022/