65932-75-4

Upstream product

• 1125-88-8 benzaldehyde dimethyl acetal 
• 14155-23-8 methyl 4,6-O-benzylidene-β-D-glucopyranoside 
• 64482-53-7 (4aR,6R,7S,8aR)-7-Hydroxy-6-methoxy-2-phenyl-tetrahydro-pyrano[3,2-d][1,3]dioxin-8-one 
• 30923-29-6 1,2:5,6-Di-O-isopropyliden-α-D-glucofuranose-3-d 

Relevant academic research and scientific papers

α-Hydrogen elimination in some 3- and 4-triflates of α-D- glycopyranosides

In previous papers [A. El Nemr and T. Tsuchiya, Tetrahedron Lett., 36 (1995) 7665-7668; A. El Nemr, T. Tsuchiya, and Y. Kobayashi, Carbohydr. Res., 293 (1996) 31-59] we reported new reactions that occur when some carbohydrate triflates are treated with MeLi (or BuLi) in ether, giving C-methyl (or butyl) or unsaturated compounds. Both reactions may be explained by α-hydrogen elimination in the triflates. This paper is an extension of the previous work and describes the mechanism of unsaturation of some 3- or 4-triflylates of α-D-glycopyranosides. By using deuterated analogs, it was found that methyl 2-O-benzyl-4,6-O-benzylidene-3-O-triflyl-α-D-glucopyranoside gives the 2,3- and 3,4-unsaturated compounds through a-hydrogen elimination, and the corresponding allopyranoside gives the 2,3-unsaturated compound through α- and β- (for 14) and α-hydrogen eliminations (for 19). Carbene formation is proposed as the key intermediate for the former eliminations, and a 1 → 2 proton-shift is proposed as the key reaction for the latter.

Regioselective mono-oxidation of Non-protected carbohydrates by brominolysis of the tin intermediates

Most of the glycosides examined were smoothly oxidized by the bis-tributyltin oxide-bromine method without protection of the other hydroxyl groups to the mono-oxo derivatives in high yield and with high regioselectivity.The regioselectivity (position of oxidation) can be predicted from two independent rules: anomeric control (the oxidation takes place at C-3 for the glycosides which have an equatorial glycosidic linkage and at C-4 for those which have an axial glycosidic linkage) and axial oxidation for cis-1,2 glycols.Keywords - carbohydrate; glycoside; oxidation; regioselective oxidation; bis-tributyltin oxide-bromine; dibutyltin oxide-bromine; brominolysis; oxo-glycoside; 13C-NMR.