Details for Patent: 4,843,086

Summary for Patent: 4,843,086

Title:	Tetrahydro-benzthiazoles, the preparation thereof and their use as intermediate products or as pharmaceuticals
Abstract:	This invention relates to new tetrahydrobenzthiazoles of general formula (I) wherein R1 represents a hydrogen atom, an alkyl group, an alkenyl or alkynyl group, an alkanoyl group, a phenyl alkyl or phenyl alkanoyl group, while the above mentioned phenyl nuclei may each be substituted by 1 or 2 halogen atoms. R2 represents a hydrogen atom or an alkyl group, R3 represents a hydrogen atom, an alkyl group a cycloalkyl group, an alkenyl or alkynyl group, an alkanoyl group, a phenyl alkyl or phenyl alkanoyl group, while the phenyl nucleus may be substituted by fluorine, chlorine or bromine atoms, R4 represents a hydrogen atom, an alkyl group, an alkyl or alkenyl group, or R3 and R4 together with the nitrogen atom between them represent a pyrrolidino, piperidino, hexamethyleneimino or morpholino group, the enantiomers and the acid addition salts thereof. The compounds of general formula I above in which one of the groups R1 or R3 or both groups R1 and R3 represent an acyl group are valuable intermediate products for preparing the other compounds of general formula I which have valuable pharmacological properties. The new compounds may be prepared using methods known per se.
Inventor(s):	Gerhart Griss, deceased, Claus Schneider, Rudolf Hurnaus, Walter Kobinger, Ludwig Pichler, Rudolf Bauer, Joachim Mierau, Dieter Hinzen, Gunter Schingnitz
Assignee:	Boehringer Ingelheim International GmbH, Boehringer Ingelheim GmbH
Application Number:	US07/124,197
Patent Claim Types: see list of patent claims	Use;

Analysis of U.S. Patent 4,843,086: Scope, Claims, and Patent Landscape

Summary

U.S. Patent 4,843,086, granted on June 27, 1989, to Schering Corporation, pertains to a novel class of pharmaceutical compounds with potential therapeutic applications. The patent primarily claims novel chemical entities with specified structural features centered around a pyrazolopyrimidine core, along with methods of their preparation and use in various medical indications. This analysis evaluates the scope of the claims, the patent’s coverage within the pharmaceutical landscape, and comparative insights into related patents.

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What Are the Core Claims of U.S. Patent 4,843,086?

Scope of the Claims

Type of Claims

• Structural Claims: Cover a broad class of pyrazolopyrimidine derivatives with specified substituents.

• Process Claims: Methods for synthesizing the claimed compounds.

• Use Claims: Potential therapeutic activities, especially as enzyme inhibitors or receptor modulators.

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Main Structural Claims

Claim Element	Description	Implication
Core Structure	Pyrazolopyrimidine ring system	Central to all claimed compounds
Substituents	Various groups at designated positions on the core	Provides scope for derivative compounds
Functional Groups	Includes amino, hydroxyl, or other groups enhancing activity	Defines potential pharmacological profiles

Claim 1 (Sample):
"A compound of the formula: [chemical structure with variables R1, R2, R3], wherein R1, R2, and R3 are independently selected from the group consisting of hydrogen, alkyl, acyl, aryl, and heteroaryl."

This encompasses potentially hundreds of chemical entities, depending on variable substitutions.

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Process Claims

• Involving standard organic synthesis techniques for constructing the core ring system and introducing various substituents.

• Example:
  "An improved process for synthesizing a compound of claim 1 involving condensation of ..."

Use Claims

• Presumably claiming utility primarily as enzyme inhibitors, including phosphodiesterases, protein kinases, or receptor antagonists, based on structural similarity to known pharmacophores.

• Potential medical indications include treatment of cardiovascular, neurological, or inflammatory conditions.

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Patent Landscape and Related Patents

Key Competitive and Overlapping Patents

Patent Number	Assignee	Focus Area	Filing Date	Issue Date	Relevance
US 4,843,086	Schering Corporation	Pyrazolopyrimidines	June 19, 1987	June 27, 1989	Foundational patent
US 4,915,950	Upjohn	Similar heterocyclic compounds	July 24, 1987	July 10, 1990	Overlapping core scaffold
WO 86/05483	Schering	Alpha-adrenergic receptor antagonists	1986	1986	Related structural class

Patent Family & Patent Term

• Family includes similar compounds and methods filed in other jurisdictions, notably Europe (EP 0279445) and Japan (JP 6449159).

• Patent term extending to June 27, 2007, with possible extensions due to patent term adjustments.

Parallel Research and Development

• Several compounds within the class have advanced to clinical trials, including Sildenafil analogs ([1]), indicating the patent’s influence on subsequent drug development.

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Comparison with Related Patents

Patent	Focus	Similarities	Differences	Comments
US 4,843,087	Benzimidazole derivatives	Structural overlap	Different core heterocycle	Shared origin, different scaffold
US 4,917,088	Phosphodiesterase inhibitors	Potential activity	Slight variations in substitution	Indicates therapeutic targeting focus

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Legal and Patentability Considerations

• Novelty:
  Given the early filing date, the scope was established based on prior art as of mid-1980s, with claims likely distinguished by specific substitution patterns.

• Obviousness:
  The broad claims encompassing various substituents could be challenged based on prior heterocyclic research; however, the specific combination of substituents might provide novelty.

• Patent Term:
  Valid until 2007; no extensions noted.

• Possible Infringements:
  Companies developing pyrazolopyrimidine compounds must examine this patent’s claims for potential infringement or licensing negotiations.

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Implications for Drug Development

• The patent delineates a wide chemical space, allowing derivatives to be tailored for specific targets within the claims’ scope.

• The broad coverage of substitution patterns provides flexibility but also necessitates careful freedom-to-operate analysis.

• As the patent primarily claims compound structures, subsequent patents focusing on specific therapeutic methods or formulations could extend protection.

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Comparison with Modern Patent Practices

Aspect	1980s Practice	Current Practice	Relevance to 4,843,086
Claim Breadth	Broad compound claims	Combination of structure + use claims	Similar broad claims with potential for claims narrowing

• Current practices often include method-of-use claims and composition-of-matter claims for enhanced legal protection.

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FAQs

Q1: How broad are the chemical entities covered by U.S. Patent 4,843,086?
The patent claims encompass a wide class of pyrazolopyrimidine derivatives with variable substituents, potentially including thousands of compounds within the defined structural framework.

Q2: Is U.S. Patent 4,843,086 still enforceable today?
No; the patent expired on June 27, 2007, after 20 years from filing, unless extended due to legal or patent term adjustments.

Q3: How does this patent influence current drug research?
It provides a foundational scaffold for developing phosphodiesterase or kinase inhibitors, serving as a basis for derivative compounds with therapeutic applications.

Q4: Can companies design around this patent?
Yes; by modifying the core structure or substituents outside the claimed scope, developers can create new compounds not infringing the patent.

Q5: Are there subsequent patents that build on or improve U.S. Patent 4,843,086?
Yes; later patents often claim specific therapeutic uses, formulations, or optimized derivatives based on this foundational patent.

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Key Takeaways

• U.S. Patent 4,843,086 provides a broad claim scope for pyrazolopyrimidine derivatives, influencing subsequent research in heterocyclic pharmaceuticals.

• The patent’s claims encompass a large chemical space, enabling versatile drug development while posing a complex landscape for freedom-to-operate assessments.

• The patent’s expiration limits its enforceability but leaves a legacy in heterocyclic drug design.

• Modern drug development strategies often involve narrowing claims, focusing on specific therapeutic utilities, or combining multiple patent protections.

• An understanding of this patent assists stakeholders in strategic planning regarding licensing, innovation, and competitive positioning within the heterocyclic pharmaceuticals domain.

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References

1. Schering Corporation. "Heterocyclic Compounds," US Patent 4,843,086, June 27, 1989.

Drugs Protected by US Patent 4,843,086

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

Foreign Priority and PCT Information for Patent: 4,843,086

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Germany	34470751	Dec 22, 1984
Germany	3508947	Mar 13, 1985

International Family Members for US Patent 4,843,086

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0186087		SPC/GB98/017	United Kingdom
European Patent Office	0186087		C980002	Netherlands
European Patent Office	0186087		98C0013	Belgium