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Methyl 1,2,3,4-tetrahydroquinoxaline-6-carboxylate and preparation method thereof

A technology of tetrahydroquinoxaline and methyl carboxylate, applied in the direction of organic chemistry, can solve the problems of expensive raw materials, low yield, high pressure, etc., and achieve the effect of simple preparation method, short synthetic route and mild reaction

Inactive Publication Date: 2018-12-14
ZHENGZHOU UNIVERSITY OF LIGHT INDUSTRY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, if the synthesis of tetrahydroquinoxaline compounds is prepared by ring formation, the steps are longer, the yield is low, there are many by-products, and the raw materials are expensive, so it is difficult to prepare in batches, which greatly limits the development of tetrahydroquinoxaline compounds. Inexpensive preparation and applications require
In particular, there are few reports on the types and synthesis methods of carboxylic acid tetrahydroquinoxalines, and there are few reports on the synthesis methods of tetrahydroquinoxalines found in searches (Journal of the Chemical Society, 1963, p. 4763-4766), but the used The method is catalytic hydrogenation, which requires high pressure and is not easy to operate

Method used

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Examples

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preparation example Construction

[0018] The preparation method of 1,2,3,4-tetrahydroquinoxaline-6-carboxylic acid methyl ester of the present invention, the steps are as follows:

[0019] (1) Suspend 3,4-diaminobenzoic acid (1) in anhydrous methanol, then add concentrated sulfuric acid, heat the reaction solution in an oil bath at 80-90°C for 10-12 hours, wait until the reaction is complete, reduce Remove methanol by pressure steaming, pour the residue into ice water, and filter with suction to obtain methyl 3,4-diaminobenzoate (2);

[0020] (2) Dissolve methyl 3,4-diaminobenzoate (2) in DMF, then add [1,4]dioxane-2,3-diol (a), then heat to 80~90°C for reaction 6 to 8 hours, then extracted, washed with water, and dried to obtain methyl quinoxaline-6-carboxylate (3);

[0021] (3) Redissolve methyl quinoxaline-6-carboxylate (3) in methanol, add sodium borohydride, react at 80-90°C for 1-2 hours, and evaporate under reduced pressure to remove excess Methanol, then extracted and dried to obtain methyl 1,2,3,4-t...

Embodiment 1

[0028] The preparation method of the 1,2,3,4-tetrahydroquinoxaline-6-carboxylic acid methyl ester of the present embodiment is as follows:

[0029] (1) Synthesis of methyl 3,4-diaminobenzoate (2)

[0030] Take a 100ml single-necked bottle, add 3.04g (0.02mol) of 3,4-diaminobenzoic acid (1), add 50mL of methanol, stir to dissolve, then add concentrated sulfuric acid 19.6g (0.2mol), stir at 90°C for 12 Hour. After the reaction was completed, the methanol was distilled off under reduced pressure, the residue was poured into ice water, and dried by suction to obtain 3.26 g of methyl 3,4-diaminobenzoate (2), with a yield of 98.1%.

[0031] ESI-MS: m / z: [M+1]:167.

[0032] 1 H NMR (300 MHz, CDCl 3 ): δ 7.44 (d, 1H), 7.38 (d, 1H), 6.64 (d, 1H), 3.82 (s, 3H), 3.52 (s, 4H).

[0033] 13 C NMR (75 MHz, DMSO-d 6 ): δ 51.62, 114.86, 118.31, 121.03, 123.22, 133.08, 140.39, 167.33.

[0034] (2) Synthesis of methyl quinoxaline-6-carboxylate (3)

[0035] Take a 100ml single-necked bot...

Embodiment 2

[0043] The preparation method of the 1,2,3,4-tetrahydroquinoxaline-6-carboxylic acid methyl ester of the present embodiment is as follows:

[0044] (1) Synthesis of methyl 3,4-diaminobenzoate (2)

[0045] Take a 100ml single-necked bottle, add 3.04g (0.02mol) of 3,4-diaminobenzoic acid, and add 50mL of methanol, stir to dissolve, then add 9.8g (0.1mol) of concentrated sulfuric acid, and stir at 90°C for 12 hours. After the reaction was completed, the methanol was distilled off under reduced pressure, the residue was poured into ice water, and dried by suction to obtain 3.17 g of methyl 3,4-diaminobenzoate (2), with a yield of 95.4%.

[0046] (2) Synthesis of methyl quinoxaline-6-carboxylate (3)

[0047]Take a 100ml single-necked bottle, add 3.32g (0.02mol) of methyl 3,4-diaminobenzoate (2) and 30ml of N,N-dimethylformamide, stir to dissolve, and then add [1, 4] Dioxane-2,3-diol (a) 2.4 g (0.02 mol). Stir at 90°C for 8 hours. Then, 3.4 g of methyl quinoxaline-6-carboxylate ...

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Abstract

The invention discloses methyl 1,2,3,4-tetrahydroquinoxaline-6-carboxylate and a preparation method thereof. The structure formula of methyl 1,2,3,4-tetrahydroquinoxaline-6-carboxylate is defined in the specification. The preparation method comprises the following steps: firstly, a cheap starting raw material 3,4-diaminobenzoic acid is suspended in anhydrous methanol, and then methyl 3,4-diaminobenzoate is obtained by catalytic esterification with concentrated sulfuric acid; secondly, quinoxaline-6-methyl carboxylate is synthesized by cyclic condensation of methyl 3,4-diaminobenzoate with [1,4] dioxane-2,3-diol; and finally, quinoxaline-6-methyl carboxylate is reduced by a common reductant sodium borohydride to obtain methyl 1,2,3,4-tetrahydroquinoxaline-6-carboxylate. The preparation route and method have the advantages of cheap reagents, mild reaction conditions, and easy purification treatment of intermediate steps and products. Provided is the new method for preparing methyl 1,2,3,4-tetrahydroquinoxaline-6-carboxylate.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a preparation method of methyl 1,2,3,4-tetrahydroquinoxaline-6-carboxylate. Background technique [0002] Tetrahydroquinoxaline compounds have very diverse pharmacological activities, such as better anticancer activity and antitumor activity, many drug molecules and natural products contain tetrahydroquinoxaline structures or fragments, so tetrahydroquinoxaline Oxaline derivatives are important pharmaceutical intermediates. However, if the synthesis of tetrahydroquinoxaline compounds is prepared by ring formation, the steps are longer, the yield is low, there are many by-products, and the raw materials are expensive, so it is difficult to prepare in batches, which greatly limits the development of tetrahydroquinoxaline compounds. Inexpensive preparation and application needs. In particular, there are few reports on the types and synthesis methods of carbox...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D241/42
CPCC07D241/42
Inventor 靳清贤李争光胡路平唐佳利白向阳甄摇摇
Owner ZHENGZHOU UNIVERSITY OF LIGHT INDUSTRY
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