Neramexane Synthesis via Intermediate Extraction

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Solution Overview

Problem

Current methods for preparing Neramexane are inefficient, resulting in low yields and significant waste production, making large-scale industrial production economically unfeasible.

Innovation Solution

A method that omits traditional purification steps such as distillation and recrystallization by using non-purified intermediates in the reaction sequence, employing reactions like isophorone conversion to 3,3,5,5-tetramethylcyclohexanone with methylmagnesium chloride and copper(I) halides, followed by subsequent conversions without intermediate purification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional purification steps (distillation, recrystallization) are performed at each reaction step, then product purity is maintained, but manufacturing complexity and production time increase significantly

Engineering Contradiction:
Improveproduct purityVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts and removes the purification steps from the traditional five-step synthesis process, performing only essential workup procedures (washing, drying, concentration) while omitting intermediate distillation and recrystallization steps. This reduces process complexity from five full purification cycles to minimal processing at each stage, while the final product still achieves sufficient purity for pharmaceutical use.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention maintains continuous production flow by eliminating interruptive purification steps between reactions. Each reaction step proceeds directly to the next without breaking the production sequence for purification, thereby reducing overall manufacturing time and operational complexity while maintaining acceptable product quality.

Inventive Principle:
Principle #20Continuity of useful action

2Manufacturing precision

If traditional purification steps are performed at each reaction step, then product quality is ensured, but production time and manufacturing cost increase

Engineering Contradiction:
Improveproduct qualityVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The invention removes time-consuming purification operations (distillation, recrystallization) from the synthesis pathway, retaining only essential workup steps. This extraction of non-essential purification activities reduces total production time from the traditional multi-day process to a more efficient timeline while still delivering product of sufficient quality for pharmaceutical application.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention applies partial purification action - performing only the minimum necessary workup steps (washing, drying, concentration) at each stage rather than complete purification. This partial approach is sufficient to maintain adequate product quality while dramatically improving production efficiency and reducing manufacturing costs.

Inventive Principle:
Principle #16Partial or excessive action

3Loss of substance

If complete purification is performed at each step, then waste from purification processes is minimized, but the number of processing steps and resource consumption increase

Engineering Contradiction:
Improvewaste reductionVSAvoidprocessing time
Core Design Contradiction:
Loss of substanceVSLoss of time

Solution Approach 1:

The invention extracts and eliminates waste-generating purification steps (distillation, recrystallization) from the synthesis process. By removing these resource-intensive operations, the process reduces both material waste and energy consumption associated with heating, cooling, and solvent recovery, while also reducing the time required for each production cycle.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The reaction conditions and workup procedures are optimized to allow the process to self-purify to a sufficient degree without requiring additional purification interventions. The sequential reactions and selective workup steps enable the process to maintain adequate purity levels through its own inherent chemistry rather than requiring external purification assistance.

Inventive Principle:
Principle #25Self-service

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 increases the yield of Neramexane to at least 60% by weight, allowing for economical industrial-scale production while minimizing waste and maintaining product quality sufficient for medicinal use.

Implementation Method 1

converting isophorone to 3,3,5,5-tetramethylcyclohexanone with methylmagnesium chloride and copper(I) halides

Methodology Applied
Scientific EffectNucleophilic addition: Chemical Bonding

Implementation Method 2

converting 3,3,5,5-tetramethylcyclohexanone to 1,3,3,5,5-pentamethylcyclohexanol by Grignard reaction with methylmagnesium iodide

Methodology Applied
Scientific EffectGrignard reaction: Chemical Bonding

Implementation Method 3

converting 1,3,3,5,5-pentamethylcyclohexanol to 1-chloroacetamido-1,3,3,5,5-pentamethylcyclohexane by chloroacetonitrile in a Ritter reaction

Methodology Applied
Scientific EffectRitter reaction: Chemical Bonding

Implementation Method 4

subsequent cleavage of the chloroacetamido group in amide with thiourea

Methodology Applied
Scientific EffectNucleophilic substitution: Chemical Bonding

Data Source

PatentEP2448910B1Method of preparing neramexane
Publication Date: 2013.05.15 MERZ PHARMA GMBH & CO KGAA
  • EP2448910B1 patent drawingFigure 1~2
  • EP2448910B1 patent drawingFigure 3
  • EP2448910B1 patent drawingFigure 4~5

AI summary

Method of producing a salt of 1-amino-1,3,3,5,5-pentamethylcyclohexane comprising steps (i) to (v): (i) converting isophorone to 3,3,5,5-tetramethylcyclohexanone; (ii) converting 3,3,5,5-tetramethylcyclohexanone obtained in step (i) to 1- hydroxy-1,3,3,5,5-pentamethylcyclohexane; (iii) converting 1-hydroxy-1,3,3,5,5-pentamethylcyclohexane obtained in step (ii) to 1-chloroacetamido-1,3,3,5,5-pentamethylcyclohexane; (iv) converting 1-chloroacetamido-1,3,3,5,5-pentamethylcyclohexane obtained in step (iii) to 1-amino-1,3,3,5,5-pentamethylcyclohexane; wherein at least one of 3,3,5,5-tetramethylcyclohexanone, 1-hydroxy-1,3,3,5,5- pentamethylcyclohexane, 1-chloroacetamido-1,3,3,5,5-pentamethylcyclohexane, is not subjected to a purification step.