Reductive Amination of 6-Keto Morphinans via Catalytic Transfer Hydrogenation
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Solution Overview
Problem
Current methods for synthesizing 6-amino morphinan compounds lacking the 4,5-epoxy ring fail to provide selective and efficient production of diastereomerically or epimerically enriched products, leading to the formation of unwanted epimers and diastereomers in low yield.
Innovation Solution
A process involving the reductive amination of a 6-keto morphinan compound using an amine source, a transition metal catalyst, and a hydrogen donor with an anion, in the presence of a proton acceptor, to form 6-amino morphinan compounds with reduced 6-alpha-amino epimer content, achieving diastereomeric or epimeric enrichment without the use of hydrogen gas or highly reactive reducing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used for synthesizing 6-amino morphinan compounds, then the reaction can proceed, but unwanted epimers and diastereomers are formed in high amounts, resulting in low selectivity
Solution Approach 1:
The invention changes the chemical parameters of the reaction system by introducing a transfer hydrogenation condition with a hydrogen donor and catalyst, replacing conventional reduction methods. This parameter change enables high selectivity for the desired 6-amino morphinan product while minimizing unwanted epimers and diastereomers, resolving the contradiction between selectivity and yield
Solution Approach 2:
The invention uses a hydrogen donor as an intermediary substance that mediates the reduction process. The hydrogen donor transfers hydrogen atoms to the imine intermediate formed during reductive amination, enabling selective formation of the desired product without requiring highly reactive reducing agents, thus improving both selectivity and yield
2Productivity
If highly reactive reducing agents are used, then the reduction can proceed efficiently, but unwanted side reactions occur and functional groups are reduced, resulting in low reliability
Solution Approach 1:
The invention changes the reactivity parameter of the reducing system by using transfer hydrogenation with a hydrogen donor instead of highly reactive reducing agents. This milder approach maintains reaction efficiency while significantly improving functional group tolerance and reliability, as the hydrogen transfer is more selective and controllable
Solution Approach 2:
The invention employs a hydrogen donor that can be readily consumed in the reaction, replacing expensive and hazardous highly reactive reducing agents. The hydrogen donor serves its purpose and is consumed, providing a safe, reliable, and cost-effective alternative that tolerates various functional groups
3Productivity
If hydrogen gas is used for reduction, then the reductive amination can proceed, but safety hazards and operational complexity increase, resulting in reduced ease of operation
Solution Approach 1:
The invention replaces gaseous hydrogen with a liquid or solid hydrogen donor, eliminating the need for pressurized gas handling equipment. This substitution maintains reaction efficiency while dramatically simplifying operational procedures and improving safety, as no special gas handling infrastructure is required
Solution Approach 2:
The invention uses a readily available hydrogen donor that can be handled as a simple liquid or solid reagent, replacing expensive and hazardous hydrogen gas. The hydrogen donor is consumed in the reaction, providing a safe, simple, and cost-effective alternative that improves ease of operation
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 process enables the production of 6-amino morphinan compounds with enhanced diastereomeric or epimeric enrichment, achieving yields of at least 60% and minimizing the presence of unwanted 6-alpha-amino epimers to less than 15%, thus overcoming the limitations of existing synthesis methods.
Implementation Method 1
contacting a 6-keto morphinan with an amine source, a hydrogen donor comprising an anion, a transition metal catalyst, and a proton acceptor to form a 6-amino morphinan
Implementation Method 2
reducing a compound comprising Formula (I) in the presence of an amine source, a hydrogen donor comprising an anion, a transition metal catalyst, and a proton acceptor
Data Source
AI summary
The present invention provides compositions of 6-amino morphinan compounds and process for their synthesis. In particular, the processes provide for the reductive amination of 6-keto morphinans by catalytic transfer hydrogenation, to produce 6-amino morphinan compounds, which are epimerically and/or diastereomerically enriched.