US RE37314 (US Reissue): What the Claims Actually Cover and How It Sits in the US Patent Landscape
What does RE37314 claim cover at the molecule level?
US RE37314 is a reissue with claims drafted as a Markush-style genus around a defined structural scaffold, where the claim scope is driven by three classes of substituent variables (R1, R2/R3, and R4) plus a core heteroatom/functional group variable X. The claims then narrow in dependent claim steps and by explicit stereochemistry.
Core structure and the three degrees of variation
Claim 1 recites “a compound represented by formula (I)” with the following variable definitions:
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R1 can be one of:
1) Lower alkyl (1 to 3 substituents allowed), substituents chosen from halogen, amino, cyano
2) C6 to C12 aromatic group (1 to 3 substituents allowed), substituents chosen from lower alkyl, halogen, amino, cyano
3) C1 to C6 lower alkyl substituted by C6 to C12 aromatic group (1 to 3 substituents allowed) with substituents chosen from lower alkyl, halogen, amino, cyano
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R2 and R3 each independently can be:
1) Hydrogen
2) Lower alkyl (1 to 3 substituents allowed), substituents chosen from halogen, amino, cyano
3) C6 to C12 aromatic group (1 to 3 substituents allowed), substituents chosen from lower alkyl, halogen, amino, cyano
-
R4 can be:
1) Hydrogen
2) lower alkyl
3) a cation capable of forming a non-toxic pharmaceutically acceptable salt
X is the key functional-group switch
- X can be:
- Sulfur, oxygen, or sulfonyl, or imino
- If imino, it can be substituted by: formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl
- “amino substituted by sulfonyl or alkyl-sulfonyl”
- “sulfonyl substituted by alkyl, amino or alkylamino”
- The claim also notes a dotted line indicating “presence or absence of a double bond,” or “corresponding ring-closed lactone.”
Net effect on scope: claim 1 is a broad chemistry genus constrained by the underlying formula (I) scaffold. The breadth is largely controlled by (i) allowed substituent classes and (ii) how broadly “imino substituted” is interpreted, but it is still tethered to the scaffold of formula (I) and to the structural presence/absence of the double bond or lactone correspondence.
What are the exact narrowing steps in dependent claims?
Dependent claims tighten the genus around the imino variant and then around specific stereochemistry.
Claim 2: X is imino with a defined substitution set
Claim 2 limits claim 1 by requiring:
- X = imino, substituted by:
- formyl
- acetyl
- propionyl
- butyryl
- isobutyryl
- valeryl
- isovaleryl
- amino substituted by sulfonyl or alkylsulfonyl
- sulfonyl substituted by alkyl, amino or alkylamino
Claim 3: further narrows the imino substitution
Claim 3 narrows claim 2 by limiting X to:
- imino substituted by:
- formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl
- alkylsulfonylamino
- alkylsulfonyl
This is a narrower substitution vocabulary than claim 2 because it separates “amino substituted by sulfonyl or alkylsulfonyl” down to specific “alkylsulfonylamino” and “alkylsulfonyl,” rather than keeping the broader amino/sulfonyl permutations.
Claim 4: locks stereochemistry
Claim 4 specifies:
- (3R, 5S)-dihydroxy configuration
This is a meaningful narrowing because stereoisomers can avoid literal infringement, depending on whether formula (I) without stereodefinition is read as covering multiple stereochemical embodiments.
How directly does the claim set map to a specific known compound?
Claims 6-8 are explicit product recitations and salt forms that typically function as “center-of-gravity” infringement targets, not just theoretical genus coverage.
Claim 6: explicit compound identity
Claim 6 recites a named chemical structure:
- 7-(4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl)-(3R,5S)-dihydroxy-(E)-6-heptenoic acid
- “in the form of a non-toxic pharmaceutically acceptable salt thereof.”
Claim 7 and 8: explicit salts
- Claim 7: sodium salt
- Claim 8: calcium salt
Net effect: even if claim 1 is interpreted broadly, the claim set also includes direct coverage of the specific scaffold instantiation (the compound in claim 6) and two concrete salt embodiments (sodium and calcium). That structure is the anchor for enforcement and design-around planning: if an entity makes the same stereochemistry and functional pattern but changes only the salt, claim 7/8 narrows options but does not necessarily eliminate claim 6 (salt still implied). If it changes the cation class, claim 1’s R4 “cation capable of forming a non-toxic pharmaceutically acceptable salt” can still create literal read-through, depending on the exact embodiment.
What is the functional “claim geography” (genus vs. product vs. formulation)?
The set is layered:
1) Genus claim (1): formula (I) with R1/R2/R3/R4 and X variables plus double-bond/lactone correspondence
2) Genus-to-subgenus constraints (2-3): require X = imino with specific imino substitution types
3) Stereochemical lock (4): (3R,5S)-dihydroxy
4) Composition claim (5): pharmaceutical composition using the claimed compound as active ingredient with an excipient
5) Product definition (6): explicit structure of a particular compound in non-toxic salt form
6) Salt embodiments (7-8): sodium and calcium salts
This structure matters for freedom-to-operate (FTO): a competitor cannot assume that avoiding a “named compound” stops exposure if the competitor still falls inside the genus or subgenus and shares the same X substitution class and stereochemistry.
How broad is the chemical search space implied by claim 1?
Claim 1’s breadth comes from the combination of:
- R1: three disjoint options (lower alkyl, aromatic, or aryl-substituted alkyl), each allowing 1 to 3 substituents selected from halogen, amino, cyano (and in the aromatic option also allowing lower alkyl)
- R2/R3: independently H, lower alkyl with up to 3 substituents from halogen/amino/cyano, or aromatic with up to 3 substituents from lower alkyl/halogen/amino/cyano
- R4: H, lower alkyl, or a salt-forming cation
- X: heteroatom/sulfonyl group or imino with a large enumerated substitution universe (including specific acyl substituents and sulfonyl/sulfonamide patterns)
- Double bond presence/absence or lactone correspondence: indicates the claim contemplates multiple tautomeric/cyclized forms of the core
Practical read: claim 1 is engineered to be robust against substituent variation while keeping the scaffold fixed. Claim 2-4 then constrain X to “imino with enumerated substitutions” and fix stereochemistry.
What is the infringement-relevant boundary between claim 1 and claim 2/3?
- If a candidate compound uses X ≠ imino (for example sulfur/oxygen/sulfonyl), claim 2 and claim 3 do not apply, but claim 1 still may.
- If X = imino but the substitution is not among the enumerated imino substituents, claim 2 and 3 do not apply; claim 1 may still apply only if the substitution still fits the broader “imino which may be substituted by…” language. In this text, the substitution list in claim 1 already includes the same enumerated items as claim 2, plus additional language about sulfonyl/amino/alkyl-sulfonyl substitution. Claim 3 then narrows further.
What is the likely “patent landscape” shape in the US around RE37314?
Within US practice, a reissue like RE37314 typically indicates one of two landscape patterns:
- A broadened or corrected claim set relative to the original patent that is now reissued, or
- A claim set that preserves enforceable coverage while addressing prosecution history or claim clarity
In terms of landscape positioning, this reissue claim set functions as a gate around:
1) The exact chemical entity (claim 6) and its sodium and calcium salts (claims 7-8)
2) Closely related imino-substituted and stereochemically defined analogs (claims 2-4 plus claim 1)
3) Formulation coverage tied to the same active ingredient (claim 5)
Even without mapping all co-existing continuations, divisionals, and later filings, the internal structure of the claims signals that RE37314 is intended to control both commercial product embodiments (especially the explicit structure and salts) and workable analog space around the same scaffold.
What design-arounds are directly suggested by the claim text (not by inference)?
Based on literal claim elements, avoidance routes are constrained to changing at least one material requirement:
- Stereochemistry: switching away from (3R,5S)-dihydroxy can defeat claim 4, and in many claim constructions may defeat claim 6 if the explicit stereochemistry is part of the definition.
- X identity: changing X from imino to sulfur/oxygen/sulfonyl avoids claim 2/3, while potentially remaining in claim 1 depending on scaffold fit.
- Imine/imino substitution type: selecting imino substitution not within the enumerated list can defeat claims 2/3, while claim 1 may still read if the substitution still falls inside claim 1’s broader “may be substituted by” wording.
- Salt form: using salt forms other than sodium or calcium avoids claim 7/8, but claim 6 still captures “non-toxic pharmaceutically acceptable salt thereof.” Claim 1’s R4 also includes “a cation capable of forming” such salts.
Key Takeaways
- RE37314 claim 1 is a formula (I) genus with explicit substituent classes for R1, independent variation for R2/R3, and an X variable that covers imino (with extensive enumerated substitutions) and other heteroatom/sulfonyl options, plus double-bond/lactone correspondence.
- Claims 2-3 narrow to X = imino with enumerated acyl and sulfonyl/sulfonamide-related substitutions; claim 4 fixes (3R,5S)-dihydroxy.
- Claims 6-8 provide direct, product-level coverage of a specific compound identity and its sodium and calcium salts; claim 5 adds composition coverage tied to the same active ingredient.
- The enforcement target is dual: the explicit commercial structure and salt embodiments, plus a surrounding analog space limited by the scaffold, X substitution category, and stereochemistry.
FAQs
1) Does RE37314 mainly protect a specific drug or a broad chemical family?
It protects both: claim 1 is a genus over formula (I), while claims 6-8 specifically recite an explicit compound and its sodium and calcium salts.
2) What element is most likely to be used to narrow infringement analysis in practice?
X (especially whether it is imino) and the (3R,5S)-dihydroxy stereochemistry, because dependent claims 2-4 attach directly to those requirements.
3) If a product changes from a sodium salt to another salt, is it automatically out of scope?
No. Claim 7 is sodium-specific and claim 8 is calcium-specific, but claim 6 covers the compound “in the form of a non-toxic pharmaceutically acceptable salt,” and claim 1’s R4 includes salt-forming cations.
4) If a candidate changes only aromatic substituents on the scaffold, is it still potentially covered?
Potentially. Claim 1 allows substantial variation in R1 and R2/R3 through permitted aromatic/lower alkyl/halogen/amino/cyano substituent patterns, while keeping the scaffold and functional definition intact.
5) Do the composition claims add protection beyond the active ingredient?
Claim 5 adds protection for a pharmaceutical composition containing an effective amount of the claimed compound with a pharmaceutical excipient.
References
[1] United States Patent and Trademark Office. “US RE37314” (reissue patent record).
