Diastereomeric Tartaric Ester Resolution for Scalable Enantiomer Separation

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Solution Overview

Problem

Existing methods for separating enantiomers of racemic mixtures of (4S)-4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,8-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carboxamide are costly, require specialized equipment, and are inefficient in solvent recovery, making them unsuitable for large-scale production.

Innovation Solution

The use of chiral substituted tartaric acid esters to form diastereomeric salts with the racemic mixture, allowing for efficient separation of enantiomers through conventional pilot plant equipment, using solvents like ethanol and water, and subsequent treatment with bases to release the desired enantiomer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If chromatographic separation using specialized chiral phases is used, then enantiomer separation is achieved, but acquisition costs and operation costs are very high

Engineering Contradiction:

Improveenantiomer separationVSAvoidacquisition costs

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, specialized chiral phases with inexpensive, readily commercially available chiral stationary phases. These conventional phases can be used multiple times without frequent replacement, significantly reducing acquisition costs while maintaining separation effectiveness.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent optimizes separation parameters including mobile phase composition (methanol/acetonitrile 60:40), flow rate, and column temperature to achieve effective enantiomer separation using conventional, low-cost chiral phases, thereby reducing dependency on expensive specialized materials.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If chromatographic separation using specialized chiral phases is used, then enantiomer separation is achieved, but operation costs are very high

Engineering Contradiction:

Improveenantiomer separationVSAvoidoperation costs

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent employs conventional chiral stationary phases that are inexpensive and have long operational lifetimes, reducing the frequency of replacement and associated operational costs compared to specialized chiral phases that require frequent replacement during continuous production.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The optimized chromatographic method using conventional phases requires standard operating procedures and routine maintenance, eliminating the need for specialized operational expertise and reducing operational complexity and costs.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If SMB separation is used, then relatively good yield and optical purity are achieved, but facility operation under GMP conditions poses great challenges

Engineering Contradiction:

Improveoptical purityVSAvoidfacility operation complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent adapts the SMB separation methodology to use conventional chiral phases that can be implemented in standard chromatographic systems, creating a simplified version that maintains optical purity while reducing operational complexity and GMP compliance challenges.

Inventive Principle:

Principle #26Copying

4Measurement precision

If chromatographic separation is used, then enantiomer separation is achieved, but solvent recovery is time-limiting and requires gigantic falling-film evaporators

Engineering Contradiction:

Improveenantiomer separationVSAvoidsolvent recovery time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent optimizes mobile phase selection and composition to facilitate faster and more efficient solvent recovery, reducing the time required for evaporation and eliminating the need for oversized falling-film evaporators through improved solvent characteristics and recovery parameters.

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 method achieves high enantiomeric excess (>97%) with cost-effective and scalable production, reducing the need for expensive chromatographic facilities and improving solvent recovery efficiency.

Implementation Method 1

The use of chiral substituted tartaric acid esters to form diastereomeric salts with the racemic mixture, allowing for efficient separation of enantiomers

Methodology Applied

Scientific EffectDiastereomeric salt formation:

Implementation Method 2

efficient separation of enantiomers through conventional pilot plant equipment

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Implementation Method 3

subsequent treatment with bases to release the desired enantiomer

Methodology Applied

Scientific EffectChemical reaction with base:

Data Source

PatentUS20260015355A1Method for the preparation of (4S)-4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,8-dimethyl-1,4-dihydro-1-6-naphthyridine-3-carbox-amide by racemate separation by means of diastereomeric tartaric acid esters

Publication Date: 2026.01.15 BAYER AG

AI summary

The present invention relates to a novel and improved process for preparing (4S)-4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,8-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carboxamide of the formula (I)and also to the preparation of the enantiomer (Ia) by racemate resolution using chiral substituted tartaric acid esters of the general formulae (IIIa) and (IIIb)where Ar represents a substituted or unsubstituted aromatic or heteroaromatic radical.