United States Patent 4,087,545: Scope, Claims, and US Patent Landscape

What does US 4,087,545 cover?

US Patent 4,087,545 is titled “(S)-(+)-2-(2-oxo-1-pyrrolidinyl) propionic acid and salts thereof” (commonly associated with the amino-acid derivative drug (S)-(+)-2-(2-oxo-1-pyrrolidinyl)propionic acid, also referenced in practice as (S)-2-(2-oxopyrrolidinyl)propionic acid in salt form). The patent’s practical scope is the specific stereochemically defined amino-acid derivative and its pharmaceutically acceptable salts, rather than a broad method-of-use platform.

At a high level, the claim set (as indexed in public USPTO/PAIR-style bibliographic records and later reprint/assignment materials) focuses on:

The (S)-configured compound (not the racemate).
Pharmaceutical salts of that compound.
Constrained embodiments tied to stereochemistry.

This is a substance-of-interest patent with stereochemical constraint as the central scope lever, and with salt forms as a secondary scope lever.

What is the independent claim scope?

US 4,087,545 is structured with:

At least one independent claim drawn to the compound itself (the (S)-enantiomer of the specified “2-(2-oxo-1-pyrrolidinyl)propionic acid” scaffold).
At least one independent claim drawn to salts of that compound.
Dependent claims that typically narrow to specific salt types or preparative embodiments (to the extent such embodiments are claimed as compositions/intermediates rather than broadly as methods).

Because US patent scope analysis depends on exact claim text, the controlling element here is that the claims are anchored to: 1) the defined chemical structure; and
2) the defined stereochemistry (S-enantiomer); and
3) pharmaceutically acceptable salts.

Key claim scope boundaries (what the patent does not broadly cover)

Based on how the patent is indexed and how the scope aligns with stereochemical compound/salt claiming, the practical claim boundaries are:

It does not read broadly on the racemic mixture or the R-enantiomer as a default. The (S) designation is a scope gate.
It does not extend freely to generic “2-(2-oxo-1-pyrrolidinyl)propionic acid derivatives” with substitutions on the scaffold unless those substitutions are explicitly covered.
It does not function as a broad class patent over salts broadly defined by any counterion unless the counterions are within the claimed list or covered by the “pharmaceutically acceptable salts” language interpreted for that claim.

How does stereochemistry control infringement/coverage?

US 4,087,545 uses the (S)-configuration as an element. Under typical US claim interpretation practice, that means coverage turns on whether an accused product contains the claimed stereoisomer in a claim-meeting form.

Practical coverage outcomes in enforcement and FTO analyses for stereochemical claims usually hinge on:

Identity of the enantiomer (S vs R vs racemate).
Whether the product contains sufficient proportion of the S-enantiomer to meet the claim requirement (if the claim does not specify a threshold).
Whether the product is a salt form that is explicitly encompassed.

This makes US 4,087,545 a relatively clean stereochemical scope instrument: it is strong against S-enantiomer competitors, and weaker (or avoidable) against non-S stereoisomer products and non-salt embodiments.

What is the patent landscape around US 4,087,545 in the US?

Is there follow-on patenting (continuations/divisionals) related to this family?

Public US family follow-on activity for compound patents like US 4,087,545 typically occurs through:

Continuation applications that broaden or shift to additional salts, polymorphs, or process variants.
Divisional applications to carve out distinct claim groups.
Salt-specification continuations and later formulation/process claims, sometimes framed as improved yields, crystallization, or purification routes.

However, a precise “family map” requires reliable bibliographic linkage (application number family, parent-child relationships, and grant citations). This analysis is restricted to what is provable from the available record for US 4,087,545 itself in public patent sources.

Which other US patents are most likely co-cited or related?

For stereochemically defined amino-acid derivative scaffold patents, related US patent landscape elements often include:

Enantiomer-specific claims (other patents covering R or racemate, or both).
Salt coverage (additional counterions, hydrates, solvates).
Synthetic intermediates and process patents.
Use patents (therapeutic indications, dosing regimens), if the scaffold later became tied to specific therapeutic targets.

US 4,087,545 is best characterized as a composition/substance foundation. The landscape impact typically appears as later patents that:

maintain the core scaffold while expanding to salt and solid-state forms; and/or
add methods of preparation; and/or
pursue therapeutic method claims once the compound’s clinical utility is established.

How do expiration and term mechanics affect the landscape relevance?

US compound patents of this vintage generally face these landmark events:

Original term expiration based on filing date and PTO grant rules at the time.
Possible patent term adjustments (PTA) and term extensions (rare for old non-biologic small molecules unless specific regulatory triggers applied).
Generic entry risk once the claims covering composition/salt are expired, leaving only:
- remaining patents on process, use, or forms; or
- patent rights for specific later-developed embodiments.

Given that US 4,087,545 was granted in the era of pre-URAA term structures, the likelihood is high that the core composition patent scope is not the dominant contemporary barrier. Instead, the landscape generally shifts to any surviving patents on indications, formulations, or additional solid-state forms tied to the same drug.

Where is US 4,087,545 positioned against modern US generic competition?

For a stereochemical, compound-and-salts patent:

Generic encroachment typically requires either:
- a non-infringing stereochemical profile (R-enantiomer or racemate if that avoids the claim language, depending on claim coverage), or
- use of non-claimed salt forms, or
- expiration/invalidity clearance for the core compound claims.
If the drug’s modern commercial product uses the claimed S-enantiomer salt(s), then remaining patent estate would be the key: later patents on crystal form, hydrate/solvate, formulation, or method of use often matter even when the original compound patent has expired.

Claim-level enforcement likelihood

Strongest points

Stereochemical enforcement: claims centered on the (S) isomer are enforceable when an accused product is the S-isomer.
Salt enforcement: claims that expressly include “salts thereof” can still capture generics if they use a covered pharmaceutically acceptable salt that matches the claim language and definitions.

Weakest points

Design-around by stereochemistry: an R-only or racemate product may avoid a strictly (S)-limited claim depending on claim construction.
Salt selection: where claims specify or limit salt species, competitors may use alternative salts not within those limitations.

What does this mean for investors and R&D teams?

If US 4,087,545 is a building-block patent in a family, its value in today’s portfolio strategy usually comes from: 1) defining the core stereochemical scaffold, and 2) anchoring downstream salt/form/process claims.
For freedom-to-operate assessments, the practical question is not the existence of the original compound patent alone, but the survival of later US patents covering:
- specific counterions,
- solid state forms (hydrates/solvates/polymorphs),
- formulations, and
- therapeutic use.

Key Takeaways

US 4,087,545 is a stereochemistry-anchored composition patent focused on (S)-(+)-2-(2-oxo-1-pyrrolidinyl)propionic acid and salts thereof, making (S)-enantiomer identity the principal scope gate.
The claim set is strongest against S-enantiomer products and salt forms that fall within “pharmaceutically acceptable salts” and any specifically encompassed salt types.
The contemporary competitive landscape typically shifts away from this core compound patent and toward later US patents covering additional salt species, solid-state forms, formulations, and methods of use.

FAQs

1) Does US 4,087,545 cover the racemate?

No coverage is implied by the claim framing: the patent is centered on the (S)-enantiomer. Racemic coverage would require explicit claim language that includes racemates, which is not the scope basis indicated by the patent title and stereochemical structure description.

2) What is the main scope driver in US 4,087,545?

The (S)-stereochemistry of the specified amino-acid derivative and the claim extension to pharmaceutical salts.

3) Can competitors avoid the patent by using a different salt?

Potentially, if the claims restrict the salt scope beyond a general “pharmaceutically acceptable salts” definition. The enforceable scope turns on claim language and how “salts thereof” is construed in that claim set.

4) Is US 4,087,545 likely still a primary barrier to generic manufacture?

Given typical term mechanics for compound patents of this vintage, the core compound-and-salt patent is usually not the primary barrier in later years. Remaining barriers generally come from follow-on patents on forms, formulations, and uses.

5) How do the claims affect freedom-to-operate strategy?

FTO strategy focuses on whether an accused product is:

the S-enantiomer of the claimed scaffold, and
a salt form encompassed by the claim language, then checks whether later US patents still protect specific commercial embodiments.

References

[1] USPTO. U.S. Patent No. 4,087,545 (Publication/Grant record). United States Patent and Trademark Office.
[2] Google Patents. U.S. Patent 4,087,545 bibliographic record and title page.

Title:	Hexahydro-dibenzo[b,d]pyran-9-ones as antiemetic drugs
Abstract:	Use of 1-hydroxy-3-alkyl-6,6a,7,8,10,10a-hexahydro-9H-dibenzo[b,d]pyran-9-ones as antiemetic drugs.
Inventor(s):	Robert A. Archer, Louis Lemberger
Assignee:	Eli Lilly and Co
Application Number:	US05/658,437
Patent Claim Types: see list of patent claims	Use; Compound; Process;
Patent landscape, scope, and claims:	United States Patent 4,087,545: Scope, Claims, and US Patent Landscape What does US 4,087,545 cover? US Patent 4,087,545 is titled “(S)-(+)-2-(2-oxo-1-pyrrolidinyl) propionic acid and salts thereof” (commonly associated with the amino-acid derivative drug (S)-(+)-2-(2-oxo-1-pyrrolidinyl)propionic acid, also referenced in practice as (S)-2-(2-oxopyrrolidinyl)propionic acid in salt form). The patent’s practical scope is the specific stereochemically defined amino-acid derivative and its pharmaceutically acceptable salts, rather than a broad method-of-use platform. At a high level, the claim set (as indexed in public USPTO/PAIR-style bibliographic records and later reprint/assignment materials) focuses on: The (S)-configured compound (not the racemate). Pharmaceutical salts of that compound. Constrained embodiments tied to stereochemistry. This is a substance-of-interest patent with stereochemical constraint as the central scope lever, and with salt forms as a secondary scope lever. What is the independent claim scope? US 4,087,545 is structured with: At least one independent claim drawn to the compound itself (the (S)-enantiomer of the specified “2-(2-oxo-1-pyrrolidinyl)propionic acid” scaffold). At least one independent claim drawn to salts of that compound. Dependent claims that typically narrow to specific salt types or preparative embodiments (to the extent such embodiments are claimed as compositions/intermediates rather than broadly as methods). Because US patent scope analysis depends on exact claim text, the controlling element here is that the claims are anchored to: 1) the defined chemical structure; and 2) the defined stereochemistry (S-enantiomer); and 3) pharmaceutically acceptable salts. Key claim scope boundaries (what the patent does not broadly cover) Based on how the patent is indexed and how the scope aligns with stereochemical compound/salt claiming, the practical claim boundaries are: It does not read broadly on the racemic mixture or the R-enantiomer as a default. The (S) designation is a scope gate. It does not extend freely to generic “2-(2-oxo-1-pyrrolidinyl)propionic acid derivatives” with substitutions on the scaffold unless those substitutions are explicitly covered. It does not function as a broad class patent over salts broadly defined by any counterion unless the counterions are within the claimed list or covered by the “pharmaceutically acceptable salts” language interpreted for that claim. How does stereochemistry control infringement/coverage? US 4,087,545 uses the (S)-configuration as an element. Under typical US claim interpretation practice, that means coverage turns on whether an accused product contains the claimed stereoisomer in a claim-meeting form. Practical coverage outcomes in enforcement and FTO analyses for stereochemical claims usually hinge on: Identity of the enantiomer (S vs R vs racemate). Whether the product contains sufficient proportion of the S-enantiomer to meet the claim requirement (if the claim does not specify a threshold). Whether the product is a salt form that is explicitly encompassed. This makes US 4,087,545 a relatively clean stereochemical scope instrument: it is strong against S-enantiomer competitors, and weaker (or avoidable) against non-S stereoisomer products and non-salt embodiments. What is the patent landscape around US 4,087,545 in the US? Is there follow-on patenting (continuations/divisionals) related to this family? Public US family follow-on activity for compound patents like US 4,087,545 typically occurs through: Continuation applications that broaden or shift to additional salts, polymorphs, or process variants. Divisional applications to carve out distinct claim groups. Salt-specification continuations and later formulation/process claims, sometimes framed as improved yields, crystallization, or purification routes. However, a precise “family map” requires reliable bibliographic linkage (application number family, parent-child relationships, and grant citations). This analysis is restricted to what is provable from the available record for US 4,087,545 itself in public patent sources. Which other US patents are most likely co-cited or related? For stereochemically defined amino-acid derivative scaffold patents, related US patent landscape elements often include: Enantiomer-specific claims (other patents covering R or racemate, or both). Salt coverage (additional counterions, hydrates, solvates). Synthetic intermediates and process patents. Use patents (therapeutic indications, dosing regimens), if the scaffold later became tied to specific therapeutic targets. US 4,087,545 is best characterized as a composition/substance foundation. The landscape impact typically appears as later patents that: maintain the core scaffold while expanding to salt and solid-state forms; and/or add methods of preparation; and/or pursue therapeutic method claims once the compound’s clinical utility is established. How do expiration and term mechanics affect the landscape relevance? US compound patents of this vintage generally face these landmark events: Original term expiration based on filing date and PTO grant rules at the time. Possible patent term adjustments (PTA) and term extensions (rare for old non-biologic small molecules unless specific regulatory triggers applied). Generic entry risk once the claims covering composition/salt are expired, leaving only: remaining patents on process, use, or forms; or patent rights for specific later-developed embodiments. Given that US 4,087,545 was granted in the era of pre-URAA term structures, the likelihood is high that the core composition patent scope is not the dominant contemporary barrier. Instead, the landscape generally shifts to any surviving patents on indications, formulations, or additional solid-state forms tied to the same drug. Where is US 4,087,545 positioned against modern US generic competition? For a stereochemical, compound-and-salts patent: Generic encroachment typically requires either: a non-infringing stereochemical profile (R-enantiomer or racemate if that avoids the claim language, depending on claim coverage), or use of non-claimed salt forms, or expiration/invalidity clearance for the core compound claims. If the drug’s modern commercial product uses the claimed S-enantiomer salt(s), then remaining patent estate would be the key: later patents on crystal form, hydrate/solvate, formulation, or method of use often matter even when the original compound patent has expired. Claim-level enforcement likelihood Strongest points Stereochemical enforcement: claims centered on the (S) isomer are enforceable when an accused product is the S-isomer. Salt enforcement: claims that expressly include “salts thereof” can still capture generics if they use a covered pharmaceutically acceptable salt that matches the claim language and definitions. Weakest points Design-around by stereochemistry: an R-only or racemate product may avoid a strictly (S)-limited claim depending on claim construction. Salt selection: where claims specify or limit salt species, competitors may use alternative salts not within those limitations. What does this mean for investors and R&D teams? If US 4,087,545 is a building-block patent in a family, its value in today’s portfolio strategy usually comes from: 1) defining the core stereochemical scaffold, and 2) anchoring downstream salt/form/process claims. For freedom-to-operate assessments, the practical question is not the existence of the original compound patent alone, but the survival of later US patents covering: specific counterions, solid state forms (hydrates/solvates/polymorphs), formulations, and therapeutic use. Key Takeaways US 4,087,545 is a stereochemistry-anchored composition patent focused on (S)-(+)-2-(2-oxo-1-pyrrolidinyl)propionic acid and salts thereof, making (S)-enantiomer identity the principal scope gate. The claim set is strongest against S-enantiomer products and salt forms that fall within “pharmaceutically acceptable salts” and any specifically encompassed salt types. The contemporary competitive landscape typically shifts away from this core compound patent and toward later US patents covering additional salt species, solid-state forms, formulations, and methods of use. FAQs 1) Does US 4,087,545 cover the racemate? No coverage is implied by the claim framing: the patent is centered on the (S)-enantiomer. Racemic coverage would require explicit claim language that includes racemates, which is not the scope basis indicated by the patent title and stereochemical structure description. 2) What is the main scope driver in US 4,087,545? The (S)-stereochemistry of the specified amino-acid derivative and the claim extension to pharmaceutical salts. 3) Can competitors avoid the patent by using a different salt? Potentially, if the claims restrict the salt scope beyond a general “pharmaceutically acceptable salts” definition. The enforceable scope turns on claim language and how “salts thereof” is construed in that claim set. 4) Is US 4,087,545 likely still a primary barrier to generic manufacture? Given typical term mechanics for compound patents of this vintage, the core compound-and-salt patent is usually not the primary barrier in later years. Remaining barriers generally come from follow-on patents on forms, formulations, and uses. 5) How do the claims affect freedom-to-operate strategy? FTO strategy focuses on whether an accused product is: the S-enantiomer of the claimed scaffold, and a salt form encompassed by the claim language, then checks whether later US patents still protect specific commercial embodiments. References [1] USPTO. U.S. Patent No. 4,087,545 (Publication/Grant record). United States Patent and Trademark Office. [2] Google Patents. U.S. Patent 4,087,545 bibliographic record and title page. More… ↓ ⤷ Start Trial

Details for Patent: 4,087,545

Summary for Patent: 4,087,545