80245-09-6

Upstream product

• 95821-86-6 methyl-(O²,O³-diacetyl-O⁴,O⁶-dibenzoyl-β-D-glucopyranoside) 
• 98-88-4 benzoyl chloride 
• 71117-37-8 (2R,4aR,6R,7R,8R,8aS)-6-Methoxy-2-phenyl-hexahydro-pyrano[3,2-d][1,3]dioxine-7,8-diol 
• 6605-40-9 methyl 2,3,4,6-tetra-O-benzyl-β-D-glucopyranoside 

Relevant academic research and scientific papers

Site-selective and stereoselective O-alkylation of glycosides by Rh(II)-catalyzed carbenoid insertion

Carbohydrates are synthetically challenging molecules with vital biological roles in all living systems. Selective synthesis and functionalization of carbohydrates provide tremendous opportunities to improve our understanding on the biological functions of this fundamentally important class of molecules. However, selective functionalization of seemingly identical hydroxyl groups in carbohydrates remains a long-standing challenge in chemical synthesis. We herein describe a practical and predictable method for the site-selective and stereoselective alkylation of carbohydrate hydroxyl groups via Rh(II)-catalyzed insertion of metal carbenoid intermediates. This represents one of the mildest alkylation methods for the systematic modification of carbohydrates. Density functional theory (DFT) calculations suggest that the site selectivity is determined in the Rh(II)-carbenoid insertion step, which prefers insertion into hydroxyl groups with an adjacent axial substituent. The subsequent intramolecular enolate protonation determines the unexpected high stereoselectivity. The most prevalent trans-1,2-diols in various pyranoses can be systematically and predictably differentiated based on the model derived from DFT calculations. We also demonstrated that the selective O-alkylation method could significantly improve the efficiency and stereoselectivity of glycosylation reactions. The alkyl groups introduced to carbohydrates by OH insertion reaction can serve as functional groups, protecting groups, and directing groups.

Catalytic Site-Selective Acylation of Carbohydrates Directed by Cation-n Interaction

Site-selective functionalization of hydroxyl groups in carbohydrates is one of the long-standing challenges in chemistry. Using a pair of chiral catalysts, we now can differentiate the most prevalent trans-1,2-diols in pyranoses systematically and predictably. Density functional theory (DFT) calculations indicate that the key determining factor for the selectivity is the presence or absence of a cation-n interaction between the cation in the acylated catalyst and an appropriate lone pair in the substrate. DFT calculations also provided a predictive model for site-selectivity and this model is validated by various substrates.

A facile chemoselective deacetylation in the presence of benzoyl and p-bromobenzoyl groups using p-toluenesulfonic acid

The acetyl group was chemoselectively cleaved in the presence of p-toluenesulfonic acid (p-TsOH) in CH2Cl2/MeOH without affecting the benzoyl (benzoate and p-bromobenzoate) groups and no transesterification product was observed. The treatment of protected carbohydrates with p-TsOH·H2O at room temperature usually required a longer reaction time than at 40°C. Other types of sulfonic acid such as 10-camphorsulfonic (CSA) led to similar results.

REGIOSELECTIVE O-DEACYLATION OF FULLY ACYLATED GLYCOSIDES AND 1,2-O-ISOPORPYLIDENEALDOFURANOSE DERIVATIVES WITH HYDRAZINE HYDRATE

On hydrazinolyis in 1:4 acetic acid-pyridine, and in pyridine, partisl O-deacylation of fully acylated methyl glycosides and some other glycosyl compounds ( 23 compounds ) was found to be induced, to give, in good yields, products bearing one free hydroxy