Optically Active Cyclopropylamine Synthesis via Hofmann Rearrangement
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Solution Overview
Problem
Existing processes for producing optically active 2-(disubstituted aryl) cyclopropylamine and 2-(disubstituted aryl) cyclopropane carboxamide derivatives are unsuitable for commercial production due to safety concerns, low yield, and economic inefficiencies, particularly involving explosive intermediates and insufficient stereoselectivity.
Innovation Solution
A process using optically active styrene oxide as a starting material and a Hofmann rearrangement with sodium hypochlorite to produce optically active cyclopropylamine derivatives, which is safer and more economical, and a method for synthesizing optically active 2-arylcyclopropane carboxamide derivatives with high optical purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Curtius rearrangement via acid azide intermediate is used to produce optically active 2-aryl cyclopropylamine derivatives, then the amine derivative can be obtained, but safety concerns arise due to the explosive properties of the acid azide intermediate
Solution Approach 1:
The patent extracts and eliminates the harmful acid azide intermediate from the synthesis pathway by employing alternative methods (Hofmann rearrangement of optically active 2-aryl cyclopropane carboxamides or direct aminocarbonylation) that bypass the formation of explosive azide compounds, thereby maintaining process feasibility while dramatically improving safety
Solution Approach 2:
The patent converts the potentially harmful Curtius rearrangement pathway into a beneficial alternative by using Hofmann rearrangement conditions with sodium hypochlorite and sodium hydroxide, which safely transform the carboxamide into the desired amine derivative without generating explosive intermediates
2Reliability
If Hofmann rearrangement using sodium hypochlorite is used to produce optically active 2-aryl cyclopropylamine derivatives, then the process is safer and more economical, but yield is reduced
Solution Approach 1:
The patent optimizes reaction parameters including the molar ratio of reactants (1:2.25:9 for carboxamide:sodium hypochlorite:sodium hydroxide), temperature control (30-40°C), and reaction time to maximize yield while maintaining the safety advantages of the Hofmann rearrangement method
Solution Approach 2:
The patent employs excess sodium hypochlorite (2.25 equivalents) and sodium hydroxide (9 equivalents) to ensure complete conversion of the carboxamide substrate, compensating for any losses and achieving satisfactory yields (67-89%) while maintaining safe reaction conditions
3Quantity of substance
If existing processes for producing optically active 2-(disubstituted aryl) cyclopropylamine and 2-(disubstituted aryl) cyclopropane carboxamide derivatives are used, then the compounds can be obtained, but economic inefficiencies and low yield occur
Solution Approach 1:
The patent employs inexpensive, readily available reagents such as sodium hypochlorite (common bleach) and sodium hydroxide, replacing costly specialized reagents and catalysts, thereby achieving cost-effective synthesis with yields ranging from 67-89%
Solution Approach 2:
The patent utilizes commercially available optically active 2-aryl cyclopropane carboxamides as starting materials that require minimal preparation, and employs simple aqueous base treatments to achieve the desired transformations, reducing both material and processing costs
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
The proposed process achieves high optical purity and is commercially viable, addressing safety and economic concerns while providing a cost-effective route for producing pharmaceutical intermediates.
Implementation Method 1
a Hofmann rearrangement with sodium hypochlorite to produce optically active cyclopropylamine derivatives
Implementation Method 2
causing to act sodium azide on this, corresponding acid azide is formed
Data Source
AI summary
This invention relates to optically active 2-(disubstituted aryl) cyclopropane carboxamide derivatives which are useful intermediates for the preparation of pharmaceutical agents, and in particular the compound [1S-(1α, 2α, 3β (1S*,2R*),5β)]-3-[7-[2-(3,4-difluorophenyl)-cyclopropyl]amino]-5-(propylthio)-3H-1,2,3-triazolo[4,5-d]pyrimidin-3-yl)-5-(2-hydroxyethoxy)-cyclopentane-1,2-diol.