CS240332B1 - Preparation of methyl 3,5,6-tri-O-benzoyl-aa-D-glucofuranosides - Google Patents

Abstract

Method for preparing methyl-3,5,6-tri-O-benzoyl- -D-glucofuranoside. The essence is that 1,2-O-isopropylidene-3,5,6-tri-O-benzoyl-D-glucofuranoside is treated with a solution of 0.3 to 1% by weight of hydrogen chloride in methanol at a temperature of 55 to 65 °C for 1 to 3 hours, or with an ion exchanger with functional groups in methanol for 6 hours. The method can find wide application in basic biochemical and chemical research of carbohydrates.

Description

The present invention relates to the preparation of methyl-tri-O-benzoyl-D-glucofuranoside.

The starting material for the preparation of methyl-3,5,6-tri-O-benzoyl-α-D-gtokofuranoside and methyl-3,5,6-tri-O-benzoyl- [beta] -D-glucofuranoside is 1,2-O-isopropylidene -D-glucofuranose, from which benzoyl chloride is prepared by its 3,5,6-tri-O-benzoyl derivative. J. W. H. O. Oldham, J. K. Ruhherford prepared methyl 3,5,6-tri-O-benzoyl-D-glucofuranoside as an intermediate in the synthesis of 2-O-methyl-D-glucose, which was one step longer by first carrying out hydrolysis

1,2-O-isopropylidene group in 1,2-O-isopropylidene-3,5,6-tri-O-benzoyl-D-glucofuranose and obtained 3,5,6-tri-O-benzoyl-D-glucofuranose in the next step glycosidized [J. W.H. Oldham, J.K. Rutherford: J. Am. Chem. Soc. 54, 1086 (1932)].

The essence of the invention lies in the fact that

1,2-O-isopropylidene-3,5,6-tri-O-benzoyl-D-glucofuranose is treated with a solution of 0.3 to 1 wt. hydrogen chloride in methanol at a temperature of 55 to 65 ^° C for 1 to 3 h, or a sulfo-functional ion exchanger in methanol for 6 to 14 h.

The advantage of the invention is that it shortens the synthesis of 2-O-methyl-D-glucose by one reaction step over the known synthesis.

EXAMPLE

13.7 g of 1,2-O-isopropylidene-D-glucofuranose are dissolved in 350 ml of 0.3 wt. methanolic hydrogen chloride solution and refluxed under reflux for 3 hours. After neutralizing the reaction mixture with the sulfonated ion exchanger (Amberlite IR-402) in the bicarbonate cycle, the filtrate is concentrated to give a syrupy mixture of α-α-methyl-3,5,6-tri-O-benzoyl-D-glucofuranoside. The yield is 78.2% t. j. 10.7 g.

Example 1 a d 2

The procedure was as described in Example 1 except that 1 wt. methanolic hydrogen chloride and the reaction time is reduced to 1 h. Yield 78.2%, m.p. j. 10.7 g.

EXAMPLE 3 g of 1,2-O-isopropylidene-D-glucofuranose was dissolved in 300 mim of ethanol, 10 g of sulfonated ion exchanger were added and refluxed for 6 h. After completion of the reaction, the ion exchanger is filtered off, the filtrate is treated with charcoal and concentrated to give a syrupy mixture of the α- and β-anomers of methyl-3,5,6-tri-O-benzoyl-D-glucofuranoside. The yield is 80.1% t. j. 7.9 g.

attaches

The procedure is as in Example 1, except that 5 g of a sulfonated ion exchanger is added and refluxed for 14 h. The yield is 78.3% t. j. 7.8 g.

The starting 1,2-O-isopropylidene-D-glucofuranose for the preparation of methyl-3,5,6-tri-O-benzoyl-α- and β-D-glucofuranosides is obtained by the following known method (RL Whistler, ML Wolfrom Methods in Carbohydrate Chemistry II, 321).

Example 5

To 20 g of D-glucose is added 400 ml of acetone, the mixture is cooled to 5 ° C and 16 ml of 96 wt. sulfuric acid. After the addition, the reaction mixture was stirred for an additional 5 hours. After neutralization of the reaction mixture 50 wt. aqueous sodium hydroxide solution, the resulting inorganic salts are filtered off and the filtrate is concentrated. The distillation residue is dissolved in 200 ml of 0.05 mol. Γ ¹ hydrochloric acid and heated at 40 ° C for 4 hours. The reaction solution is then / neutralized with 20 wt. sodium hydroxide solution, filtered and concentrated. The syrup obtained is crystallized from a mixture of methanol and petroleum ether. Yield: 8.8 g of 1,2-O-isopropylidene-D-glucofuranose, m.p. 161 DEG C. to an optical otáčavostl [a] _D ²⁰ -12 ° (c = 2, water). 8.8 g of 1,2-O-isopropylidene-D-glucofuranose are dissolved in 40 ml of pyridine and 18 g of benzoyl chloride are added over 1 hour with stirring at 20 ° C. The reaction mixture is then poured into 300 ml of water, the resulting syrup is extracted twice with 100 ml of chloroform. The chloroform extract is dried over sodium sulfate, concentrated and the distillation residue is crystallized from ethanol. 1,2-O-isopro is obtained. pylidene-3,5,6-tri-O-benzoyl-D-glucofuranose in 85.9% yield, ie 18.3 g, melting point 119 ° C and optical rotation [α] b ²⁰ '-9Q, 2 ^P , (c 1, chloroform).

The mixture of α- and (β-anomers of methyl-3,5,6-tri-O-benzoyl-D-glucofuranosides prepared according to Examples 1 to 4 is an intermediate in the preparation of 2-O-methyl-D-glucose. .

EXAMPLE 6 g of a mixture of .alpha.-.alpha.-methyl-3,5,6-tri-O-benzoyl-D-glucofuranosides are dissolved in 20 g of methyl iodide, 15 g of silver oxide are added and the reaction mixture is stirred. at 20 ° C. The progress of the reaction was monitored by thin layer chromatography of silica hydrate (silica gel) in benzene: ethyl acetate in 2: 1 v / v. . The distillation residue is re-methylated with 10 g of methyl iodide and 7 g of silver oxide. After working up the reaction mixture, a mixture of the α- and β-anomers of methyl-2-O-me240332 tyl-3,5,6-tri-O-benzoyl-D-glucofuranoside is obtained in a yield of 92.1%, ie 3.8 g, which used without further processing to prepare 2-O-methyl-O-glucose. 2 g of a mixture of α- and β-methyl-2-O-methyl-3,5,6-tri-O-benzoyl-D-glucofuranoside are dissolved in 30 ml of anhydrous methanol and 10 mg of sodium are added to the solution. After 4 hours debenzoylation proceeds to 100%. The reaction mixture is concentrated, and the residue is dissolved in 40 ml of 0.025 mol. 1 · ¹ sulfuric acid and heated at 90 ° C for 6 hours. After the hydrolysis is complete, the solution is neutralized with barium carbonate and filtered. Concentration of the filtrate yielded in 86.7% yield, i.e. 0.69 g of syrup, which, by crystallization from ethanol, gave 2-O-methyl-D-glucose of melting point 156-158 ° C, optical rotation [α] _D + 36.3 ° after 2 min and + 64.0 ° after 24 h (c = 1, water).

The invention may find wide application in the theoretical study of carbohydrate glycosidation as well as in the preparation of 2-O-methyl-D-glucose. These derivatives, since they have a free hydroxyl group at the C-2- position, are important intermediates in the synthesis of disaccharides with 1-2 bonds (cojibiosis, sophoros, 2-amino-2-deoxy-D-glucose, or other derivatives). we used them to prepare 2-O-methyl-D-glucose, a substance important in determining the structure of polysaccharides.

Claims (2)

240332 tyl-3,5,6-tri-O-benzoyl-D-glucofuranoside yield 92.1%, i.e. 3.8 g, which is used for the preparation of 2-O-methyl-O-glucose without further treatment. 2 g of a mixture of α- and β-methyl-2-O-methyl-3,5,6-tri-O-benzoyl-D-glucofuranoside are dissolved in 30 ml of anhydrous methanol and 10 mg of sodium are added to the solution. After 4 hours, the debenzoylation was 100%. The reaction mixture was concentrated and the residue obtained was dissolved in 40 ml of 0.025 mol. sulfuric acid was heated at 90 ° C for 6 hours. After the hydrolysis is complete, the solution is neutralized with barium carbonate and filtered. By concentrating the filtrate, 86.7% yield is 0.69 g syrup, which crystallizes from ethanol to give 2-O-methyl-D-glucose mp 156-158 ° C, optical rotation [α] D + 36.3 ° after 2 min and -) - 64.0 ° after 24 h (c = 1, water). The present invention can find wide use in the theoretical study of carbohydrate glycosidation as well as in the preparation of 2-O-methyl-D-glucose. These derivatives, while having a free hydroxyl group at the C-2- position, are important intermediates in the synthesis of disaccharides by 1-2 bonds. (kojiblose, soforose), 2-a-mine-2-deoxy-D-glucose, optionally other derivatives. In our case, we use them to prepare 2-O-methyl-D-glucose, a substance important in the determination of polysaccharides. SUBJECT A method of preparing methyl 3,5,6-tri-O-benzoyl-α- and β-D-glucofuranosides, characterized in that 1,2-O-isopropylidene-3,5,6-tri- -O-benzoyl-D-glucofuranose causes a solution of 0.3% to 1% by weight. hydrogen chloride in the present invention at 65 ° C for 1-3 hours, or by ion exchange with functional sulfonates in methanol for 6-14 hours.