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Preparation process of methyl-methyl-3, 4-dihydro-2H-pyran-5-carboxylate

A kind of technology of carboxylate and methyl, applied in the field of preparation technology of methyl-methyl-3,4-dihydro-2H-pyran-5-carboxylate, can solve the problem of expensive raw materials, difficult to obtain, expensive And other issues

Active Publication Date: 2016-02-03
SPC LIFESCI PVT LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] (v) the raw materials used are expensive and not readily available;
[0014] (vi) it becomes very expensive and time consuming to perform these reaction steps at a commercial level; and

Method used

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  • Preparation process of methyl-methyl-3, 4-dihydro-2H-pyran-5-carboxylate
  • Preparation process of methyl-methyl-3, 4-dihydro-2H-pyran-5-carboxylate
  • Preparation process of methyl-methyl-3, 4-dihydro-2H-pyran-5-carboxylate

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preparation example Construction

[0048] (1) The preparation of the necessary side chains starts from the condensation of 1-bromo-3-chloropropane of formula (I) with methyl acetoacetate of formula (II) to prepare haloketones of formula (VII).

[0049]

[0050] (2) O-alkylation of haloketones of formula (VII) with sodium methoxide under variable reaction conditions to yield the desired molecule, methyl-methyl- 3,4-Dihydro-2H-pyran-5-carboxylate with simultaneous production of methanol.

[0051]

[0052] (3) The crude product is then purified by fractional distillation, methyl-methyl-3,4-dihydro-2H-pyran-5-carboxylate of formula (IV).

[0053]

[0054] In this improved process, the reaction is carried out in the presence of an alcohol solvent selected from the group consisting of methanol, ethanol, isopropanol or n-propanol, pentanol, hexanol and propanol, preferably methanol. The improved process can be carried out with sodium methoxide in solution and powder form, said solution being suitably selecte...

Embodiment -1

[0058] Add 315.0g (2.0mol) of 1-bromo-3-chloropropane and 250.0g (2.15mol) of methyl acetoacetate to 780.0ml of alcohol solvent (preferably methanol) at 30-40°C without maintaining a nitrogen atmosphere . To the above contents, 160.0 g (2.96 mol) of sodium methoxide in the form of powder was slowly added in batches at 30-40°C under a nitrogen atmosphere. Since the reaction was exothermic, a nitrogen atmosphere had to be maintained and the temperature of the reaction mass rose immediately. The reaction is maintained at a reflux temperature of 70°C (limit) for 10-12 hours, preferably 6-8 hours, the reaction mass is cooled to 55-60°C. At this stage approximately 315.0 g of water was added at atmospheric pressure to dissolve any salts formed during the reaction in the water. Fractional distillation of the crude product yields unreacted compound of formula (I) and methanol, the solvent used in the reaction. The solvent methanol recovered by fractional distillation is not in pure...

Embodiment -2

[0060] Add 315.0g (2.0mol) of 1-bromo-3-chloropropane and 250.0g (2.15mol) of methyl acetoacetate to 780.0ml of alcohol solvent (preferably methanol) at 30-40°C without maintaining a nitrogen atmosphere . To the above contents, 184.0 g (3.4 mol) of sodium methoxide in the form of powder was slowly added in portions at 30-40°C under a nitrogen atmosphere. Since the reaction was exothermic, a nitrogen atmosphere had to be maintained and the temperature of the reaction mass rose immediately. The reaction is maintained at a reflux temperature of 70°C (limit) for 10-12 hours, preferably 6-8 hours, the reaction mass is cooled to 55-60°C. At this stage approximately 315.0 g of water was added at atmospheric pressure to dissolve any salts formed during the reaction in the water. Fractional distillation of the crude product yields unreacted compound of formula (I) and methanol, the solvent used in the reaction. The solvent methanol recovered by fractional distillation is not in pure...

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Abstract

The present invention provides an improved process for the preparation of methyl-methyl-3,4-dihydro-2H-pyran-5-carboxylate of formula (IV), comprising the steps of: (IV) (i) alkylating 1-Bromo-3-chloropropane of formula (I) with Methylacetoacetate of formula (II) to prepare haloketone of formula (VII) in presence of an alcoholic solvent; (I) (II) (VII) (ii) O-alkylating the compound of formula (VII) with sodium methoxide to obtain the desired molecule methyl-methyl-3,4-dihydro-2H-pyran-5-carboxylate of formula (IV) in its crude form; (VII) (IV) (iii) Purifying the content of step (ii) above by fractional distillation to obtain the purified molecule of formula (IV).

Description

technical field [0001] The present invention relates to a simple, economical, environmentally friendly and improved preparation of methyl-methyl-3,4-dihydro-2H-pyran-5-carboxylate of formula (IV), which It can be used as an intermediate in the synthesis of 6-chlorohexanone of the main compound chemical formula (V). [0002] Background technique [0003] Methyl-methyl-3,4-dihydro-2H-pyran-5-carboxylate of formula (IV) is also known as methyl 3,4-dihydro-6-methyl-2H-pyran- 5-carboxylate or 2H-pyran-5carboxylic acid, 3,4-dihydro-6-methyl, methyl ester or 5,6-dihydro-3-methoxycarbonyl-2-methyl-4H- pyran. Much research has been carried out in the field of preparation of said compounds. However, such compounds have been found to be widely useful as intermediates for the synthesis of the main compound, 6-chlorohexanone of formula (V), which is an important component in the preparation of the pharmaceutically active ingredient pentoxifylline. [0004] current technology [0...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D309/28
CPCC07D309/28
Inventor 斯内哈尔·R·帕特尔P·N·罗山·拉克什
Owner SPC LIFESCI PVT LTD
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