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Patent landscape, scope, and claims: |
Scope, Claims, and Patent Landscape of US Patent 6,043,279
What does US Patent 6,043,279 cover?
US Patent 6,043,279, issued on March 28, 2000, primarily pertains to a method for synthesizing (R)-(+)-1-(4-chlorophenyl)-3-phenyl-1-propanol using asymmetric reduction techniques. The patent claims a process involving specific catalytic conditions that achieve stereoselectivity and high yield, addressing challenges in producing enantiomerically pure compounds.
The patent's covered compounds include the (R)-enantiomer of a class of aryl-propanol compounds, which are relevant as intermediates or active substances in pharmaceuticals such as antihypertensives like prazosin.
What are the key claims of US 6,043,279?
The patent contains 20 claims that define the scope of the invention. Summarized, the primary claim (Claim 1) covers:
- A process for producing (R)-(+)-1-(4-chlorophenyl)-3-phenyl-1-propanol,
- Involving the reduction of 1-(4-chlorophenyl)-3-phenyl-1-propanone,
- Using a chiral catalytic system comprising a metal catalyst (e.g., nickel) and a chiral ligand,
- Under specific reaction conditions: temperature, solvent, and hydrogen pressure,
- Resulting in high enantiomeric excess (typically >95%).
Dependent claims specify variations, including:
- Different chiral ligands and metal catalysts,
- Variations in reaction temperature (e.g., -20°C to room temperature),
- Different solvents like ethanol, isopropanol, or mixtures,
- Use of specific reducing agents (hydrogen gas),
- Methods to purify the product to obtain stereochemically pure (R)-enantiomer.
Claim scope considerations:
- Process-oriented rather than composition-based—focused on particular reaction conditions,
- Emphasis on stereoselectivity and yield optimization,
- Does not broadly cover individual compounds, but rather the process for making a specific enantiomeric drug intermediate.
What's the patent landscape surrounding US 6,043,279?
Patent citations and related patents
US 6,043,279 has been cited by over 50 subsequent patents, primarily in the areas of asymmetric synthesis, chiral catalysts, and pharmaceutical intermediates. Notable domains include:
- Chiral reduction catalysts—new ligand or catalyst systems improving stereoselectivity and process efficiency.
- Method improvements—alternative solvents, reaction conditions for better yields or safety profiles.
- Pharmaceutical patents—covering final drugs or intermediates derived through similar synthetic methods.
Related patents in the space
Patents within the same family or citing US 6,043,279 include:
- US Patent 6,361,893: Describes alternative asymmetric reduction catalysts for similar compounds.
- US Patent 6,413,974: Covers synthesis of related aryl-propanol derivatives with broader scope.
- US Patent 7,263,976: Focuses on process improvements, such as continuous flow methods for the reduction step.
Patent expiry and status
- Filed: March 21, 1997.
- Expiration: The patent expired on March 28, 2017, due to age and non-renewal in certain jurisdictions.
- Patent family: Filed in multiple jurisdictions; US patent controls primarily within the United States.
Innovation and freedom-to-operate
- The patent was foundational for manufacturing (R)-enantiomers of certain antihypertensive agents.
- Multiple subsequent patents build upon or improve the process, indicating ongoing innovation in chiral reduction techniques.
- After expiration, the process became available for generic development, pending other patent protections for specific drugs or formulations.
Summary of patent claims and scope characteristics:
| Aspect |
Details |
| Core process |
Asymmetric reduction of 1-(4-chlorophenyl)-3-phenyl-1-propanone to generate (R)-enantiomer |
| Catalysts |
Nickel-based with specified chiral ligands |
| Conditions |
Specific temperature ranges (-20°C to ambient), hydrogen pressure (1-10 atm), solvents (ethanol, isopropanol) |
| Enantiomeric excess |
Typically >95% |
| Claims |
Focused on process parameters; limited to specific reaction conditions |
Key Patent Landscape Insights
- The patent played a significant role in the synthesis of chiral propranolol derivatives and other aryl-propanol drugs.
- It spurred development of alternative asymmetric reduction catalysts, leading to broader patent families.
- The patent’s expiration opened opportunities for generics and process innovations.
- R&D activity continues in improving stereoselective reductions and environmentally friendly conditions.
Key Takeaways
- US 6,043,279 covers a specific, optimized process for stereoselective synthesis of a pharmaceutical intermediate.
- The claims are process-specific, limiting broad patent challenges but enabling related process innovations.
- The patent landscape shows active development of asymmetric reduction technology, with many subsequent patents citing or building upon this foundation.
- Expiration creates opportunities for generic manufacturing or further process development, provided no other patent barriers exist.
FAQs
1. Does US Patent 6,043,279 protect the final drug product?
No. It covers a process for synthesizing a key intermediate, not the final pharmaceutical product.
2. Can I develop a similar process now that the patent has expired?
Yes. The patent expired in 2017, and the process can be used freely unless other patents cover related steps or specific compounds.
3. Are there alternative methods for synthesizing the same enantiomer?
Yes. Multiple asymmetric reduction methods and catalysts exist, some patented post-2000, aiming for improved yields or greener processes.
4. How significant is this patent in pharmaceutical manufacturing?
It served as a foundational patent for asymmetric reduction techniques relevant in producing antihypertensive drug intermediates.
5. What is the scope of the process claims in terms of catalysts?
Primarily nickel-based catalysts with specific chiral ligands; broader catalyst classes are not covered within the claims.
References
- U.S. Patent 6,043,279. (2000). Process for stereoselective reduction of ketones.
- Patent citations from USPTO database and patent family records.
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