Gas-liquid chromatography of carbohydrates

Experimental Proof for the Structure of a Thrombin-Inhibiting Heparin Molecule

“…[29] Selective acetylation of the primary alcohol function was carried out at 0 8C in pyridine using a slight excess of acetyl chloride. The monoacetate 29 was thus isolated together with a small amount of the known [30] diacetate. The position 4 of 29 was then protected as a levulinyl ester; acetolysis of the methyl group provided the diacetate 31 which gave a mixture (a:b 7:3) of the anomeric thioglycosides 32 with ethanethiol in the presence of boron trifluoride.…”

“…; C11 H 20 O 7 : calcd for C 49.99, H 7.63; found C 49.87, H 7.73.Methyl 6-O-acetyl-4-O-levulinyl-2,3-di-O-methyl-a-d-glucopyranoside(30): Levulinic acid(2.61 g, 22.5 mmol), 1-(3-dimethylaminopropyl)-3ethylcarbodiimide hydrochloride(4.32 g, 22.5 mmol) and 4-dimethylaminopyridine (0.275 mg, 2.25 mmol) were added, at room temperature, to a solution of 29(2.98 g, 11.27 mmol) in dry dioxane (112 mL). After 3.5 h, the mixture was diluted with EtOAc (400 mL) and successively washed with 5 % aq KHSO 4 , H 2 O, sat.…”