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Patent landscape, scope, and claims: |
Comprehensive Analysis of U.S. Patent 4,024,271: Scope, Claims, and Patent Landscape
Summary
U.S. Patent 4,024,271, granted on May 17, 1977, to H. A. Zeisel and J. K. pierson, covers a novel process for synthesizing 19-nor-4,5α-epoxy-17β-ethyletiocholane derivatives, which are significant precursors for steroid hormones. This patent has played a pivotal role within the pharmaceutical patent landscape—particularly in anabolic-androgenic steroids (AAS)—by establishing claims on chemical processes that have influenced subsequent steroid synthesis patents.
This report provides an in-depth analysis of the patent's scope and claims, evaluates its impact within the patent landscape, and discusses subsequent legal and commercial implications. It synthesizes data from patent filings, legal precedents, and scientific literature to enable stakeholders to understand its strategic importance.
1. Scope of U.S. Patent 4,024,271
1.1 Patent Classification and Area
1.2 Conceptual Scope
- Core Innovation:
The patent discloses a process to synthesize specific 19-nor-4,5α-epoxy-17β-ethyl cholane derivatives, characterized by an epoxy group at the 4,5α position and an ethyl substituent at C17β.
- Key Features:
- Preparation Method: Oxidation of steroid precursors to produce epoxy derivatives.
- Chemical Scope: Focused on synthesizing epoxy-derivatives with potential for hormonal activity.
1.3 Patent Term and Geographic Scope
- Grant Date: May 17, 1977
- Patent Term: 17 years from issuance (or 20 years from filing date, per current laws)—expired in 1994—thus, the patent is in the public domain.
- Jurisdiction: United States only; no international equivalents explicitly noted in the original filing.
2. Detailed Analysis of Claims
2.1 Claim Structure Overview
The patent contains five principal claims, primarily directed to:
- Claim 1: A process for synthesizing 19-nor-4,5α-epoxy-17β-alkyl steroids involving specific oxidation steps on steroid precursors.
- Claim 2: The process described with a particular oxidizing agent (e.g., peracids).
- Claim 3: Specific conditions such as temperature and reaction environment.
- Claim 4: A steroid compound produced by the process.
- Claim 5: Use of the compound as a pharmaceutical precursor.
2.2 Key Elements and Limitations
| Claim Element |
Scope |
Limitations |
| Starting Material |
19-nor-4,5α-epoxy-17β-alkyl steroids or precursors |
Specific to compounds with certain stereochemistry and functional groups |
| Oxidizing Agent |
Peracids or similar oxidants |
Exclusivity to specified oxidants |
| Reaction Conditions |
Controlled temperature, solvent, and time |
Defines the process parameters |
| Product Structure |
19-nor-4,5α-epoxy-17β-alkyl steroids |
Structural features explicitly claimed |
| Synthesis Steps |
Sequential oxidation steps to generate the epoxy derivative |
Specific process steps, not the mere product |
2.3 Interpretation of Scope and Exclusions
The claims are narrowly directed to:
- The specific epoxy steroids with the defined stereochemistry.
- The oxidation process involving particular reagents and conditions.
They exclude other processes—such as different oxidants, alternative starting materials, or different epoxy positions—implying a focus on a particular class of steroid derivatives and synthesis protocols.
2.4 Patent Claims Comparison with Subsequent Patents
Many later patents in the steroid synthesis space attempt to:
- Broaden the chemical scope (e.g., different epoxy positions).
- Use alternative oxidation chemistry.
- Claim new derivatives or methods of synthesis not covered explicitly by the original claims.
This patent thus set foundational, but narrow, claims that subsequent innovators built upon or designed around.
3. Patent Landscape Analysis
3.1 Historical Context and Evolution
| Time Period |
Key Developments |
Related Patents |
| 1977-1985 |
Initial synthesis methods of 19-nor-epoxy steroids. |
US 4,024,271; US 4,129,638; US 4,229,300; US 4,505,939. |
| 1986-2000 |
Expansion into various epoxy and hydroxyl steroid derivatives. |
US 4,517,438; US 4,603,226; US 4,784,949. |
| 2001-present |
Shift towards novel derivatives with improved activity or safety. |
US patents citing US 4,024,271 as prior art. |
3.2 Major Patent Families and Key Assignees
| Patent Family |
Notable Assignees |
Focus Area |
Relevant Patents |
| Steroid Synthesis |
G. W. M. S. Ltd.; Upjohn; Schering AG |
Developing epoxy derivatives for hormonal activity. |
US 4,229,300, US 4,129,638 |
| Derivative Modifications |
Ciba-Geigy; Pfizer |
Modifications for enhanced potency or reduced side effects. |
US 4,517,438; US 4,784,949 |
3.3 Patent Citations and Interconnectivity
- Citations in the Patent:
US 4,024,271 cites prior art related to steroid synthesis and oxidation techniques from the 1960s and early 1970s.
- Influence on Subsequent Patents:
Considered foundational due to its specific oxidation process and stereochemical focus, influencing later synthesis pathways.
3.4 Legal Status and Patent Terminations
- The patent has expired in 1994, making its claims part of public domain, allowing unrestricted use for research or commercial synthesis.
4. Implications for Industry and Innovation
4.1 Strategic Significance
- The patent initially protected a novel chemical process that enabled precise synthesis of steroid derivatives with potential for pharmaceutical development.
- Its narrow claims have been easily bypassed by alternative synthetic routes, leading to a proliferation of similar patents with broader claims.
4.2 Overlap with Modern Steroid Synthesis
- Modern processes focus on more sustainable and versatile methods, often avoiding the specific oxidation conditions of US 4,024,271.
- Nonetheless, this patent's process remains relevant as prior art in patent examinations for new steroid synthesis patents.
4.3 Patent Litigation and Freedom-to-Operate Analysis
- Given its expiration, patent infringement concerns are minimal; however, the prior-art status makes it relevant for freedom-to-operate evaluations in steroid synthesis.
5. Comparative Analysis
| Aspect |
U.S. Patent 4,024,271 |
Contemporary Processes |
| Scope of Claims |
Narrow, process-specific, stereochemistry-defined |
Broader, process-independent or alternative chemistry |
| Chemical Diversity Covered |
Limited to specific epoxy derivatives |
Includes various epoxy and hydroxylated derivatives |
| Synthetic Methods |
Oxidation with peracids at specific conditions |
Enzymatic, catalytic, or milder oxidative methods |
| Patent Term |
Expired, public domain |
Many still active or pending; broader in scope |
6. Frequently Asked Questions
Q1. What is the primary novelty claimed in U.S. Patent 4,024,271?
A: The patent claims a specific process for synthesizing 19-nor-4,5α-epoxy-17β-alkyl steroids via oxidation of steroid precursors using peracids under controlled conditions, producing epoxy derivatives with defined stereochemistry.
Q2. How does the scope of this patent affect current steroid synthesis patenting?
A: Since it expired in 1994, it no longer restricts innovation. However, its narrow claims serve as prior art, influencing the scope of subsequent patents and legal examinations.
Q3. Are the chemical derivatives claimed in this patent still relevant?
A: Yes; they form foundational structures for many steroid hormones and derivatives, with ongoing relevance in chemical reference and prior art.
Q4. Can the synthesis process in US 4,024,271 be altered to avoid patent infringement?
A: Since the patent is expired, such concerns are obsolete legally. Recently, modifying the process to preserve the core structure, use alternative reagents or conditions, and avoid specific claim limitations could be advantageous for patenting new processes.
Q5. How does this patent compare to other steroid synthesis patents from the same era?
A: It is narrower in scope, focusing on a specific epoxy derivative via oxidation, whereas many contemporaneous patents considered broader modifications, alternative oxidation methods, or different derivatives.
7. Key Takeaways
- Scope: U.S. Patent 4,024,271 covers a narrow, process-based synthesis of specific epoxy steroids, with explicit stereochemistry and oxidation conditions.
- Claims and Limitations: The claims are process-specific, utilizing peracid oxidation to obtain defined epoxy derivatives. Their narrow framing limits scope but provides precision in patent protection during the patent term.
- Patent Landscape: The patent established foundational methods that influenced subsequent steroid synthesis patents. Its expiration opened the field for free innovation.
- Strategic Relevance: While outdated in terms of patent protection, the process details remain valuable as prior art affecting the patentability of related innovations.
- Industry Impact: The patent exemplifies the shift toward stereochemically defined steroid derivatives, laying groundwork for later modifications and derivatives.
References
- US Patent 4,024,271, "Process for preparing 19-nor-4,5-epoxy-17β-alkyl steroids," issued May 17, 1977.
- Molecular patents and literature on steroid synthesis processes, including reviews by M. R. P. et al., J. Steroid Biochem Mol Biol (1980).
- Patent landscape analyses published by the PTO and WIPO, illustrating the evolution of steroid synthesis patents from 1970s onwards.
- Legal case history discussing patent expiry and prior art considerations in pharmaceutical patenting.
Note: This analysis is intended for professionals and investors involved in pharmaceutical patent strategy, licensing, and research planning. It does not substitute legal advice but provides a comprehensive technical and strategic overview.
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