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Active catalysts for stereoselective ring-opening reactions

A chiral catalyst, catalyst technology, applied in physical/chemical process catalysts, catalyst activation/preparation, organic compound/hydride/coordination complex catalysts, etc., can solve the problem of high cost, time-consuming solvent removal, and increased cost And other issues

Inactive Publication Date: 2005-10-12
SHASUN PHARMA SOLUTIONS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This requires the necessary washing equipment
Second, solvent removal takes time, making the process more expensive, and complete solvent removal is practically impossible, especially at larger scales
The remaining solvent must therefore be removed after the ring-opening reaction, further increasing the cost
Second, because the activation reaction is performed each time, there is an undesired variable factor in each ring-opening reaction

Method used

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  • Active catalysts for stereoselective ring-opening reactions
  • Active catalysts for stereoselective ring-opening reactions
  • Active catalysts for stereoselective ring-opening reactions

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0166] According to the following reaction scheme by making the chiral salen ligand, Co(OAc)·4H 2 The reaction of O, acetic acid and air in methanol produces an active catalyst:

[0167]

[0168] (R,R)-Jacobsen ligand 1 (82 g, 0.15 mol, 1.0 equiv) was added to a 3-liter three-necked round-bottom flask equipped with a mechanical stirrer, a thermometer, and an air-bubbling cannula, and then heated at ambient temperature MeOH (750 mL) was added to the vessel. Glacial acetic acid (18 g, 0.3 mol, 2.0 equiv) was then added to the flask. Add Co(OAc) to the reaction vessel 2 4H 2 O (41.9 g, 0.165 mol, 1.1 equiv) and an additional 75 mL (about 10 volumes total) of MeOH were used for flushing. The contents of the flask were stirred under open air for 30 minutes until most of the ligand solids had dissolved. A flow of air was then drawn through the dark green / brown mixture using a house vacuum through a cannula open to atmosphere with stirring for 2 hours. The contents of the fl...

Embodiment 2

[0170] According to the following reaction scheme by making the chiral salen ligand, Co(OAc) 2 4H 2 O, acetic acid and air react in excess acetic acid to produce an active catalyst:

[0171]

[0172] Add (S, S)-Jacobsen ligand 3 (2.2kg) in the reaction vessel equipped with high-speed stirrer, thermometer and air bubbling intubation, then add cobalt acetate tetrahydrate ( 1.06kg). The reaction vessel was purged with nitrogen. 18.5 kg of acetic acid was added to the reactor over a period of about 0.5 hr at room temperature with stirring started. The contents of the reaction vessel were stirred at room temperature while bubbling compressed air through the mixture at a rate of about 750 liters air / kg ligand / hour for 3 hours. Exhaust air is passed through a sodium hydroxide scrubber. The composition of the contents was monitored every 30 minutes by TLC. When the reaction was complete (>95% conversion), the air sparging was stopped, the vessel was purged with nitrogen and the...

Embodiment 3

[0174] Catalyst stability was assessed by monitoring the activity of the catalyst in the hydrolytic kinetic resolution ("HKR") of racemic epichlorohydrin versus the length of time the isolated catalyst was stored in a closed container at ambient temperature.

[0175] To a 125 mL jacketed vessel equipped with an overhead mechanical stirrer and a thermometer was added the (R,R)-Co(III)salen ligand-acetate-methanol catalyst produced according to the procedure given in Example 1 above Complex (1.66 g, 2.5 mmol, 0.5 mole % relative to racemic epoxide). Racemic epichlorohydrin (46.7 g, 0.5 mol) was added to the vessel and the temperature of the mixture was brought to 5°C with temperature controlled circulating liquid. Water (6.75 g, 0.375 mol, 0.75 equiv to racemic epoxide) was added over 2 hours using a syringe pump. After the addition was complete, the reaction was monitored by chiral GC analysis until completion of the reaction was indicated by an enantiomeric balance of >99% ep...

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Abstract

A method for making a chiral transition metal-ligand catalyst complex that is active in catalyzing stereoselective ring opening reactions includes contacting an asymmetric tetradentate ligand, in an excess of a Bronsted acid, with a salt of a first row transition metal, wherein the acidity of the conjugate acid of the salt is the same as or less than the acidity of the Bronsted acid, under conditions effective to allow formation of the active chiral transition metal-ligand catalyst complex, and forming a solution of the complex in a water-miscible, protic solvent from which the active complex can be precipitated by the addition of water and adding water to the solution to precipitate at least a portion of the complex.

Description

technical field [0001] The present invention relates to catalysts for catalyzing stereoselective ring-opening reactions, and more particularly to active transition metal-ligand catalyst complexes. Background technique [0002] Stereoselective reactions of various nucleophiles in epoxide ring-opening catalyzed by chiral (salen)Co(III) complexes provide ready access to many enantiomerically enriched chiral products , these enantiomerically enriched chiral products are useful in the pharmaceutical, agrochemical, and flavor and fragrance industries. These products can be obtained by kinetic resolution of racemic epoxides using substoichiometric amounts of nucleophiles, or by stereoselective stoichiometric reactions of nucleophiles with resolved epoxides. For these methods, generation of active Co(III) catalysts from inactive Co(II) catalysts or from chiral ligands and metal salts requires the use of appropriate solvents (typically chlorinated hydrocarbons such as dichloromethan...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D301/32B01J31/18B01J31/22B01J37/03C07B53/00C07B57/00C07B61/00C07C29/10C07C31/42C07D303/08C07F15/06
CPCB01J2531/0252B01J2531/845B01J31/2243B01J2531/96B01J2531/62B01J2231/487B01J37/031C07F15/065C07B53/00B01J31/18B01J31/34C07D303/02C07F13/00
Inventor 杰伊·F·拉罗卡尔·亨博格侯赛因·卡比尔菲利皮·莫雷尔
Owner SHASUN PHARMA SOLUTIONS LTD
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