Clopidogrel Synthesis via Kinetic Resolution and Racemization

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Solution Overview

Problem

Current methods for manufacturing Clopidogrel and its methyl tetrahydrothienopyridine acetate analogues face challenges in achieving economical, effective, and environmentally friendly industrial-scale production, with inefficiencies in chiral resolution, consumption and recycling of resolution agents, and solvent optimization.

Innovation Solution

A novel synthetic route and process involving the use of halogenphenylacetonitrile and tetrahydrothienopyridine acetonitrile intermediates, utilizing phase transfer catalysis for alkaline hydrolysis and kinetic resolution with camphor sulfonic acid, followed by racemization and recycling of chiral agents, to produce (S)-(+)-Clopidogrel and its analogues efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If indirect hydrolysis via tetrahydrothienopyridine acetamide derivatives is used, then the reaction can proceed, but the manufacturing process becomes complex and yield decreases

Engineering Contradiction:

Improvehydrolysis process simplicityVSAvoidmanufacturing yield

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The invention extracts and eliminates the unnecessary intermediate step involving tetrahydrothienopyridine acetamide derivatives from the synthesis pathway. By directly hydrolyzing compound (IV) to compound (V), the method removes the complex indirect route that reduced yield and increased process complexity, achieving both simplicity and high efficiency.

Inventive Principle:

Principle #2Taking out (Extraction)

2Productivity

If conventional chiral resolution methods are used, then Clopidogrel can be produced, but resolution efficiency is low and consumption of chiral resolution agents increases

Engineering Contradiction:

Improveproduction efficiencyVSAvoidchiral resolution agent consumption

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The invention implements a recycling system for chiral resolution agents. The unwanted (R)-enantiomer that would normally be discarded is racemized back to the racemic mixture and fed back into the resolution process. This recovery and reuse approach significantly reduces chiral agent consumption while maintaining high production efficiency of the desired (S)-Clopidogrel.

Inventive Principle:

Principle #34Discarding and recovering

3Ease of operation

If chiral resolution agents are not recycled, then the process is simpler to operate, but environmental harm increases and cost effectiveness decreases

Engineering Contradiction:

Improveprocess operational simplicityVSAvoidenvironmental impact

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The invention recycles chiral resolution agents through racemization of the unwanted enantiomer and its reintroduction into the resolution process. This recovery system reduces environmental harm by minimizing chemical waste while the integrated design keeps the operational complexity manageable, achieving both environmental protection and operational feasibility.

Inventive Principle:

Principle #34Discarding and recovering

4Ease of manufacture

If acid hydrolysis method is used as reported, then compound (V) can be obtained, but the yield is only 38% which is not competitive

Engineering Contradiction:

Improvehydrolysis method availabilityVSAvoidhydrolysis yield

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The invention changes the hydrolysis parameters by using alkaline conditions instead of acid hydrolysis. This parameter change dramatically improves the yield from 38% to 94.1%, making the process commercially competitive while maintaining the availability of a straightforward hydrolysis method.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables high-yield, cost-effective, and environmentally protective production of Clopidogrel and its analogues, with improved resolution efficiency and recycling of chiral agents, suitable for industrial-scale commercialization.

Implementation Method 1

utilizing phase transfer catalysis for alkaline hydrolysis

Methodology Applied

Scientific EffectPhase transfer catalysis: Surfactant

Implementation Method 2

kinetic resolution with camphor sulfonic acid

Methodology Applied

Scientific EffectKinetic resolution:

Implementation Method 3

racemization of unwanted chiral compounds

Methodology Applied

Scientific EffectRacemization:

Data Source

PatentUS7932391B2Method for the preparation of clopidogrel and its analogues of methyl-tetrahydrothieno[3,2-C]pyridine acetate

Publication Date: 2011.04.26 ZHEJIANG HUAHAI PHARMACEUTICAL CO LTD

AI summary

The present invention disclosed a preparation method of Clopidogrel (X=2−Cl) and its analogues of methyl tetrahydrothienopyridine acetate (I) by using halogen phenyl acetonitrile (VIII) as starting material and tetrahydrothienopyridine acetonitrile (IV), tetrahydrothienopyridine acetate (V) as key intermediates, and further using kinetic resolution to prepare the optical active Clopidogrel and compounds of methyl tetrahydrothenopridine acetate of formula (XII). The Clopidogrel of present invention is a novel high effective and safety drug for inhibition of platelet aggregation. This invention applied systematic technique of racemization of unwanted optical active enantiomer, recover recycle and reuse of resolution agent etc., with greater economic advantages and suitable for commercial scale industrial production.Wherein: X represents atoms of hydrogen, fluorine, chlorine, bromine or iodine, M represents an alkali metal ion.