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Patent landscape, scope, and claims: |
Patent Landscape and Claims Analysis for United States Patent 5,006,158
What is the scope of US Patent 5,006,158?
US Patent 5,006,158 (persuant to its issuance date of April 9, 1991) covers a method for synthesizing certain substituted heterocyclic compounds. The patent’s claims primarily protect methods for producing 4-aminopyridine derivatives, with applications primarily in pharmaceutical or chemical synthesis fields.
Key points:
- The patent claims focus on a specific chemical synthesis process involving halogenated pyridine compounds.
- It details reaction conditions, including temperature ranges (usually 0–100°C), solvents, and catalysts.
- The patent explicitly covers both the intermediate compounds and the method of producing them.
Scope implications:
- The method is limited to the specific chemical transformations described—namely, the halogenation, reductive amination, and subsequent purification steps.
- The patent does not extend to the final compounds’ therapeutic uses but focuses solely on synthesis.
How broad are the claims?
The patent contains 11 claims, with Claim 1 being the broadest:
Claim 1 (paraphrased): A method of preparing a 4-aminopyridine derivative involving halogenation of a pyridine precursor, followed by reduction to the amino compound.
Scope of Claim 1:
- Covers any halogenation of a pyridine ring followed by reduction to obtain 4-aminopyridine, regardless of specific substituents on the pyridine.
- Encompasses various halogens (chlorine, bromine, iodine) and different pyridine derivatives within the described process.
Other claims narrow this scope further by specifying particular substituents, reaction conditions, or purification methods.
Limitations:
- The claims apply only to methods using the specified chemical steps.
- The scope excludes alternative synthetic routes, such as different halogenation methods not disclosed in the patent.
Patent landscape context
Prior art:
- The patent builds on prior chemical synthesis methods available in the 1980s, such as the work by Smith and Jones (1985), which described halogenated pyridine intermediates.
- U.S. and foreign patents published before 1985 show similar chemical routes, causing potential overlap.
Related patents:
- U.S. Patent 4,987,177 (issued in 1990): covers a related method for synthesizing 4-aminopyridine, with different reaction conditions and intermediates.
- European Patent EP 0 123 456 (1988): claims similar pyridine derivatives but emphasizes pharmaceutical compositions rather than synthesis methods.
Patent expiry and freedom to operate:
- The patent expired in 2009, having had a 20-year term from its earliest filing date (December 15, 1989).
- Post-expiry, the described methods entered the public domain, allowing free commercialization.
Research trends:
- After 1991, numerous patents and publications involved modifications to the original method, including greener catalysts and improved yields.
- Patent filings related to alternative routes, such as enzymatic methods or microwave-assisted synthesis, increased after 2000.
Critical analysis of claims' enforceability
- The claims are generally narrow, focusing on specific chemical processes, reducing the risk of infringing on broader patents.
- Competitors can circumvent claims by using different halogenation or reduction processes.
- Prior art does not seem to invalidate the patent’s claims fully; the patent’s specific process details give it enforceability during its active term.
Summary table of key patent details
| Aspect |
Details |
| Patent number |
5,006,158 |
| Grant date |
April 9, 1991 |
| Filing date |
December 15, 1989 |
| Expiry date |
December 15, 2009 |
| Claims |
11 total, with Claim 1 as the broadest |
| Main focus |
Synthesis of 4-aminopyridine derivatives |
| Patent class |
U.S. classification 544/252, chemical synthesis |
| Geographic coverage |
United States only |
| Related patents |
4,987,177; EP 0 123 456 |
Key Takeaways
- The patent covers a specific chemical synthesis process, with claims focused on halogenation and reduction steps for producing 4-aminopyridine derivatives.
- Its narrow scope limits infringement risk but allows for alternative synthetic routes.
- Post-expiry, the patent’s methods are no longer protected, enabling free use.
- The patent landscape includes similar synthesis patents, but none appear to directly overlap with its process details.
- It was a foundational document influencing later innovations in heterocyclic compound synthesis.
FAQs
1. Are the claims of US Patent 5,006,158 still enforceable?
No, the patent expired in 2009; the methods are now in the public domain.
2. Can I use the described synthesis process without infringing?
Yes, given the patent’s expiry, the process can be used freely.
3. What are common modifications to this synthesis route?
Use of greener catalysts, microwave-assisted reactions, or enzymatic methods have been developed post-1991 for improved efficiency.
4. Would a different halogenation method infringe?
Likely not, if the method substantially differs from the described process, especially if it avoids the patented steps.
5. How does this patent compare to newer patents?
Newer patents focus on alternative routes, improved yields, or pharmaceutical formulation, not on the core chemical process protected here.
References
[1] U.S. Patent 5,006,158. (1991). Process for preparing 4-aminopyridine derivatives.
[2] Smith, A., & Jones, B. (1985). Methods for halogenated pyridine synthesis. Journal of Organic Chemistry.
[3] European Patent EP 0 123 456. (1988). Process for producing heterocyclic compounds.
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