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Heterocyclic carboxylic ester reducing process

A technology of heterocyclic carboxylate and heterocycle, which is applied in the field of reduction of aromatic heterocyclic carboxylate to alcohol, can solve the problems of poor solubility, high cost and high risk of lithium aluminum hydride, and achieve easy separation and purification, good thermal The effect of stability and easy recycling

Inactive Publication Date: 2004-01-21
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The limitations of using lithium aluminum hydride to reduce ethyl 5-thiazolecarboxylate and ethyl 3-pyridinecarboxylate mainly lie in: 1) the price of lithium aluminum hydride is high; 2) the solubility of lithium aluminum hydride is poor, and the solvent selection range used for reduction is small, Only limited to ether solvents such as tetrahydrofuran or diethyl ether, the actual solvent that can be selected as industrial use is tetrahydrofuran, and the solvent price is high; 3) the reaction requires anhydrous conditions, tetrahydrofuran is easy to absorb water, and the cost of processing into anhydrous tetrahydrofuran is high and dangerous; 4) Tetrahydrofuran is miscible with water, and the recovery and treatment of the solvent used to extract and isolate the product after the reaction is inconvenient and pollutes a lot

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 15

[0013] Two (2-methoxyethoxy) sodium aluminum hydride reduction method 1 of embodiment 1.5-thiazole ethyl carboxylate

[0014] Add bis(2-methoxyethoxy)sodium aluminum hydride toluene solution (7.6ml, 7.9g, 27mmol) and 15ml toluene to a dry round bottom flask. Cool the sodium bis(2-methoxyethoxy)aluminum hydride solution to -5~0°C. A solution of ethyl 5-thiazolecarboxylate (3.59 g, 22.85 mmol) and 15 ml of toluene was added dropwise to sodium bis(2-methoxyethoxy)aluminum hydride. Incubate and react at -5~0°C for 1 hour. The reaction solution was diluted with 75 ml of ethyl acetate. Add 68ml of 15% sodium hydroxide solution to the solution, stir for 30 minutes, extract three times with ethyl acetate, 40ml each time, dry over anhydrous sodium sulfate, filter, evaporate the solvent under reduced pressure, and distill under reduced pressure to obtain yellow liquid 5-hydroxymethyl Thiazole 1.63g (98-102°C / 2mmHg), yield 62%. MS(ESI): 116(M+1); 1 H-NMR: 8.737 (s, 1H), 7.701 (s, 1H...

Embodiment 25

[0015] Two (2-methoxyethoxy) sodium aluminum hydride reduction method 2 of embodiment 2.5-thiazole carboxylic acid ethyl ester

[0016] Add bis(2-methoxyethoxy)sodium aluminum hydride toluene solution (152ml, 158g, 540mmol) and 300ml toluene to a dry round bottom flask. Cool the sodium bis(2-methoxyethoxy)aluminum hydride solution to -5~0°C. A solution of ethyl 5-thiazolecarboxylate (71.8 g, 457 mmol) and 300 ml of toluene was added dropwise to sodium bis(2-methoxyethoxy)aluminum hydride. -5 ~ 0 ℃ heat preservation reaction for 1 hour. The reaction solution was diluted with 1500 ml of ethyl acetate as a solvent. Under stirring, add 22ml of water, 44ml of 10% sodium hydroxide solution and 22ml of water accordingly, stir for 30 minutes, filter with diatomaceous earth, wash with ethyl acetate three times, each 200ml, dry over anhydrous sodium sulfate, filter, evaporate under reduced pressure To solvent. Distillation under reduced pressure gave 37.2 g of yellow liquid 5-hydrox...

Embodiment 3

[0017] Two (2-methoxyethoxy) sodium aluminum hydride reduction method 3 of embodiment 3.5-thiazole formic acid ethyl ester

[0018] Add bis(2-methoxyethoxy)sodium aluminum hydride toluene solution (38ml, 39.5g, 135mmol) and 60ml of toluene to a dry round bottom flask. Cool the sodium bis(2-methoxyethoxy)aluminum hydride solution to -5~0°C. A solution of ethyl 5-thiazolecarboxylate (7.18g, 45.7mmol) and 30ml of toluene was added dropwise to sodium bis(2-methoxyethoxy)aluminum hydride. -5 ~ 0 ℃ heat preservation reaction for 1 hour. The reaction solution was diluted with 250 ml of ethyl acetate as a solvent. Under stirring, add 5.5ml of water, 11ml of 10% sodium hydroxide solution and 5.5ml of water accordingly, stir for 30 minutes, filter with diatomaceous earth, wash with ethyl acetate three times, each 50ml, dry over anhydrous sodium sulfate, filter, reduce The solvent was removed by autoclaving. Distillation under reduced pressure gave 3.78 g of yellow liquid 5-hydroxyme...

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Abstract

The present invention relates to the method of reducing aromatic heterocyclic carboxylic ester to form alcohol. Aromatic heterocyclic carboxylic ester 5-methylol thiazole and 3-methylol pyridine are reduced with bis(2-methoxyoxethyl) sodium aluminum hydride as the reductant to obtain corresponding alcohol. Bis(2-methoxyoxethyl) sodium aluminum hydride has excellent dissolvability and this makes it possible to select solvent according to the reduced matter. Bis(2-methoxyoxethyl) sodium aluminum hydride has excellent heat stability, is stable at temperature up to 140 deg.c, will not burn spontaneously in the air and thus is safe. Bis(2-methoxyoxethyl) sodium aluminum hydride and the reduced matter 5- thiazolyl ethyl formate and 3-pyridyl ethyl formate can be dissolved well in arene, cheaper than tetrahydrofuran and easier in separation.

Description

(1) Technical field [0001] The invention relates to a method for reducing aromatic heterocyclic carboxylate to alcohol. (2) Background technology [0002] Carboxylate esters are widely used in organic synthesis as important activated functional groups. The α-position active hydrogen-containing esters can carry out a series of reactions such as α-position alkylation reaction, condensation reaction with carbonyl compounds, nucleophilic substitution reaction of α-halogenated esters, addition reaction of α, β-unsaturated esters, etc. . The ester group can be transformed into other functional groups, among which the reduction of ester group to hydroxyl is an important type of transformation. At present, ester reduction methods include catalytic hydrogenation, metal sodium-alcohol method, and metal hydride negative hydrogen transfer reduction method (including aluminum hydride and borohydride). Reduction of esters by catalytic hydrogenolysis usually requires high temperature an...

Claims

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Application Information

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IPC IPC(8): C07D213/65C07D263/42C07D277/34
Inventor 靳立人刘宝丽时晓军谭斌沈阳
Owner XIAMEN UNIV
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