United States Patent 7,491,719 Landscape: What the Claims Cover, How Broad the Chemical Scope Is, and Where Generics and Licensors Can Hit or Design Around

US Patent 7,491,719 claims a family of closely related R-configured, benzo[1,4]oxazin-3-one hydrochloride/acid-addition salts with specific aryl substituent variants and defined side-chain stereochemistry. Claim scope is dominated by: (i) a core heterocycle scaffold, (ii) a constrained “R” stereochemical assignment, (iii) a limited aryl substitution menu (one anisole-type methoxyphenyl plus four fluorinated/alkoxy phenyl variants), (iv) defined secondary alcohol + tertiary amine patterns, and (v) broad coverage for acid addition salts across a large anion set. Anhydride forms and crystalline/tautomer options extend coverage into solid-state and prodrug-adjacent space.

The claims you provided are claim-set-level, but they are enough to map the chemical boundary, likely claim construction posture, design-around levers, and typical litigation attack surfaces (indefiniteness/enablement rarely succeeds in clean scaffold chemistry, while obviousness and non-infringement via structure or salt form are the primary risk vectors).

What does US Patent 7,491,719 protect: scope of the benzo[1,4]oxazin-3-one claims?

Short answer: It protects a specific class of R-6-hydroxy / R-8-hydroxy benzo[1,4]oxazin-3-one derivatives, each bearing a hydroxy-ethyl side chain with a tert-alkyl amino substituent linked to a substituted phenyl, sold or formulated as anhydrides, crystalline tautomers, and acid-addition salts.

Core scaffold and stereochemical constraint

Across the independent-looking structures in your claims, the protected motif is:

Benzo[1,4]oxazin-3-one core
Hydroxy substituent(s) at positions 6 or 8
A side chain of the type:
- 1-hydroxy-2-[2-(aryl)-1,1-dimethylethylamino]ethyl (for claim 1)
- or 2-[2-(aryl)-1,1-dimethylethylamino]-1-hydroxyethyl plus corresponding ring hydroxy position (claims 3/5/7/9)
Strong emphasis on “R” configuration in the name (claims 1, 3, 5, 7, 9 and the later salt claims that inherit the same descriptor).

This means literal infringement likely turns on whether the accused structure:

falls within the benzo[1,4]oxazin-3-one scaffold,
has the same positional hydroxy pattern,
preserves the defined R stereochemistry, and
uses the same side-chain connectivity pattern (secondary alcohol position, ethyl linkage, and tert-alkyl amino substitution pattern).

What aryl variants are actually covered?

Your claims list only these aryl substitution patterns on the phenyl ring attached to the tert-butylamino moiety:

4-methoxyphenyl (claim 1; and later salt claims 13–15)
2,4-difluorophenyl (claim 3; salt claims 16–21)
3,5-difluorophenyl (claim 5)
4-ethoxyphenyl (claim 7; and salt claims 22–27)
4-fluorophenyl (claim 9)

So the structural boundary is not “any substituted phenyl,” it is a finite menu in the asserted claim set you provided.

What’s covered by the “anhydride” dependent claims?

Claims 2, 4, 6, 8, 10 cover “the anhydride of” the compound of the immediately preceding claim(s). In practice, this usually captures:

a dehydrated ester/acid form (often from adjacent hydroxyl functionality), or
a specific internal dehydration product.

Operationally, anhydride coverage raises infringement risk for process-improper drying or storage where dehydration yields a stable anhydride. It also raises a typical prosecution-history argument for claim construction: whether “anhydride” is limited to one chemical species or includes multiple dehydration states. Given the claim language is functional (“the anhydride of the compound”), litigation often focuses on what “anhydride” means in the patent record and whether the accused material is that dehydration product.

Crystalline/tautomer option extends solid-state coverage

Claim 11 adds “crystalline form” and “optionally… crystalline tautomers.” That creates a second infringement axis:

if a manufacturer sells the same chemical entity but a different solid form, they still risk capture if that solid form is a “crystalline tautomer” within the scope.

How many different compounds are covered by claim 1–10 and what structural variations do they map to?

Short answer: The set you provided covers five parent chemical entities (claims 1, 3, 5, 7, 9) plus their anhydrides (claims 2, 4, 6, 8, 10).

Compound inventory by claim

Claim	Ring hydroxy position	Side chain aryl substituent	Protected entity type
1	6-hydroxy	4-methoxyphenyl	hydrochloride (explicit in name)
2	6-hydroxy	4-methoxyphenyl	anhydride of claim 1
3	6-hydroxy	2,4-difluorophenyl	hydrochloride (explicit in name)
4	6-hydroxy	2,4-difluorophenyl	anhydride of claim 3
5	6-hydroxy	3,5-difluorophenyl	hydrochloride (explicit in name)
6	6-hydroxy	3,5-difluorophenyl	anhydride of claim 5
7	6-hydroxy	4-ethoxyphenyl	hydrochloride (explicit in name)
8	6-hydroxy	4-ethoxyphenyl	anhydride of claim 7
9	6-hydroxy	4-fluorophenyl	hydrochloride (explicit in name)
10	6-hydroxy	4-fluorophenyl	anhydride of claim 9

Key point: your dependent claims 2/4/6/8/10 are tied to each parent. That means freedom to operate cannot simply design around “the base,” because dehydration products can remain inside the asserted claim language.

What formulations are protected by US 7,491,719: composition, excipients, salts, and solid forms?

Short answer: It protects a broad pharmaceutical composition that includes the claimed compound(s) with “pharmaceutically acceptable excipient,” plus specific protection for acid addition salts and potentially different crystalline tautomers.

Claim 12: composition claim

Claim 12:

“A pharmaceutical composition comprising a compound according to one of claims 1 to 10 and a pharmaceutically acceptable excipient.”

This is typical “composition of matter” breadth in formulation. It matters for litigation because it allows a patentee to target not only API structure but also finished dosage forms that contain any of the claimed APIs, regardless of excipient composition.

Salt strategy: acid addition salt framework

Claims 13–27 introduce:

“in the form of an acid addition salt with an acid HX”
where “X− denotes an anion with a single negative charge”
and each dependent claim enumerates a list of acceptable anions.

This is important because many generics and branded manufacturers switch salt forms to optimize:

solubility,
crystallinity and polymorph behavior,
hygroscopicity,
manufacturability,
and patent avoidance.

Here, the asserted claim set narrows the API scaffold but widens salt coverage.

Which acid addition salts are covered: what anions are explicitly included?

Short answer: For each of the five base structures (methoxyphenyl; difluoro; difluoro; ethoxyphenyl; fluoro phenyl), the claims list a large and overlapping anion menu, including halides, sulfonates, nitrates, and common organic/inorganic carboxylates.

Claim 14: anion list for methoxyphenyl salt series

Claim 14 (based on claim 13) includes:
chloride, bromide, iodide, sulphate, phosphate, methanesulphonate, nitrate, maleate, acetate, benzoate, citrate, salicylate, trifluoroacetate, fumarate, tartrate, oxalate, succinate, p-toluenesulphonate.

Claim 15 narrows slightly to a subset (removes some items relative to claim 14, but still includes chloride, bromide, sulphate, methanesulphonate, maleate, acetate, benzoate, citrate, salicylate, trifluoroacetate, fumarate, tartrate, succinate, and others listed in the claim text you provided).

Claims 17 and 18: anion lists for 2,4-difluorophenyl salt series

Claim 17 (based on claim 16) lists:
chloride, bromide, iodide, sulphate, phosphate, methanesulphonate, nitrate, maleate, acetate, benzoate, citrate, salicylate, trifluoroacetate, fumarate, tartrate, oxalate, succinate, p-toluenesulphonate.
Claim 18 (based on claim 17) uses a slightly reduced list (keeps chloride, bromide, sulphate, methanesulphonate, maleate, acetate, benzoate, citrate, salicylate, trifluoroacetate, fumarate, tartrate, succinate).

Claims 19–21: anion lists for 2,4-difluorophenyl salt series (another dependent tier)

Claims 19–21 repeat the salt framework:

Claim 20 enumerates a large list (essentially the same set as claim 17, minus/altered items as shown in your text).
Claim 21 further narrows to:
chloride, bromide, sulphate, methanesulphonate, maleate, acetate, benzote, citrate, salicylate, trifluoroacetate, fumarate, tartrate, succinate (your claim text includes the “benzote” spelling; treat as benzoate in claim construction unless the patent record uses a different term).

Claims 22–27: anion lists for 4-ethoxyphenyl salt series

Claim 23 lists:
chloride, bromide, iodide, sulphate, phosphate, methanesulphonate, nitrate, maleate, acetate, benzoate, citrate, salicylate, trifluoroacetate, fumarate, tartrate, oxalate, succinate, p-toluenesulphonate.
Claim 24 narrows to:
chloride, bromide, sulphate, methanesulphonate, maleate, acetate, benzote, citrate, salicylate, trifluoroacetate, fumarate, tartrate, succinate.
Claim 26 and 27 repeat essentially the same salt framework for the same base compound tier (as provided).

Practical consequence: salt-form switching is not a clean design-around because the asserted claim set enumerates many commercially common acid anions. A generic designer would have to pick an anion outside the enumerated set and ensure other structural elements are not implicated (stereochemistry, ring substitution pattern, and aryl variant).

Is US 7,491,719 limited to “hydrochloride,” or does it cover other acid salts broadly?

Short answer: It covers hydrochloride as part of the base compound definitions (claims 1, 3, 5, 7, 9) and then separately covers a wide acid addition salt universe in claims 13–27.

Your claim language is not “only hydrochloride.” Instead, it appears to:

define specific “hydrochloride” members at claims 1/3/5/7/9, then
add additional claim layers that cover the same API scaffold as acid addition salts with anion X− from a defined list.

So a competitor cannot avoid infringement by changing from HCl to, say, sulfate or maleate if those anions are listed in the dependent claims tied to the correct base scaffold.

How strong is the patent estate for blocking generics: what are the likely infringement and validity fault lines?

Short answer: Strength is structurally anchored in a narrow chemical class (specific aryl variants and scaffold) but is broadened through:

a composition claim,
solid-state crystalline/tautomer coverage,
dehydration product coverage (anhydrides),
and broad salt anion enumeration.

That mix generally increases enforcement leverage against “same chemistry” competitors. Validity challenges tend to focus on obviousness from close structural analogs and on whether the salt/crystal forms were enabled and supported.

Enforcement leverage points created by the claim set

Composition claim (12): targets finished products with any of the claimed APIs.
Salt enumeration (13–27): blocks common formulation salt pivots within the listed anions.
Crystalline tautomer inclusion (11): blocks some solid-form avoidance tactics.
Anhydride inclusion (2/4/6/8/10): blocks dehydration-induced product variants.

Likely non-infringement design-around levers

Swap to an aryl substituent outside the five listed variants (e.g., replace methoxy with another substituent, replace difluoro pattern with tri-fluoro, etc.).
Change the benzo[1,4]oxazin-3-one substitution pattern or hydroxy position(s) so the scaffold is not literally met.
Use a salt anion not included in the enumerated X− list in the relevant dependent claims.
Change stereochemistry so the descriptor “R” is not met (though stereochemical swaps are nontrivial in synthesis and may still risk doctrine-of-equivalents arguments, depending on claim construction).

What generic entry risks exist for competitors under US 7,491,719?

Short answer: Risks are highest for entrants using the same API family and a listed salt form. Lower risk exists only if the entrant uses a non-listed aryl variant or a non-enumerated anion salt, or if they can credibly avoid the crystalline/anhydride forms addressed in the claim set.

Highest-risk infringement scenarios

Launching a product containing one of the five base chemical entities (claims 1/3/5/7/9) in any of the enumerated salt forms covered by the appropriate dependent claims.
Launching with an API that can form the claimed anhydride during manufacture, storage, or administration, if that anhydride is within “the anhydride of” the base compound as construed.
Marketing a crystalline tautomer form that fits claim 11’s crystalline tautomer coverage.

Lower-risk entry scenarios (from a literal claim standpoint)

Using the same scaffold but an excluded anion not listed (requires careful selection and characterization).
Using a different aryl substitution pattern outside the five listed claim variants.
Using different ring substitution/hydroxy arrangement not meeting the claim-defined scaffold.

How does US 7,491,719 compare with typical chemical patents: what is broad vs narrow in claim strategy?

Short answer: This patent is “narrow on chemistry, broad on form.” It narrows by scaffold and aryl substituent selection, then broadens by covering salts and multiple solid-state variants.

Narrow elements

Defined heterocycle: benzo[1,4]oxazin-3-one
Defined R stereochemistry
Defined hydroxy position(s) and side chain architecture
Limited aryl substitution menu (five patterns)

Broad elements

Salt coverage across many anions (in dependent claims)
Crystalline forms and crystalline tautomers
Anhydride derivatives
Composition claim without excipient limitation

That profile is consistent with litigation posture where the patentee focuses on demonstrating that the accused product contains the same chemical entity (and acceptable salt/crystal form) rather than litigating broad Markush over generically “all derivatives.”

What patents commonly co-exist with US 7,491,719 for this scaffold: where would you expect related estate coverage?

Even without the patent family document set, the claim design implies typical co-existing IP layers around the same scaffold:

Earlier process patents covering synthesis routes to the R-configured benzo[1,4]oxazin-3-one intermediates and final API.
Polymorph/crystal form patents beyond the generic “crystalline form” language in claim 11.
Specific salt form patents that may further distinguish one or more anions within the enumerated list.
Method-of-treatment / use patents if the scaffold maps to a known therapeutic indication.

The provided claims themselves are chemistry/formulation-centric. For full estate mapping across “how many patents cover” the scaffold, you would normally query the entire patent family and forward citations, but the required dataset is not included here.

What is the litigation and Orange Book status of US 7,491,719?

No Orange Book listing, Paragraph IV record, court docket, or settlement term set is included in the information provided. Without those external identifiers, a status call for “Orange Book listed,” “pediatric exclusivity,” or “generic challenges filed” cannot be made from the claim text alone.

Patent landscape timeline: how to read exclusivity and expiration impact for this claim set

No filing dates, priority dates, grant date confirmation, or patent term adjustment inputs were provided beyond the patent number. A true expiration timeline requires priority and PTA/PTE facts from the patent record and linkages to FDA approvals.

Key Takeaways

US 7,491,719 claims a defined set of R-configured benzo[1,4]oxazin-3-one derivatives with five specific aryl substitution patterns and defined hydroxy/side-chain architecture.
Coverage extends beyond the parent APIs to include anhydrides and crystalline tautomers.
The salt scope in claims 13–27 is the main breadth expansion: it enumerates many common acid anion forms, making salt-form pivoting a limited design-around tactic within the listed anion universe.
Composition claim (12) allows enforcement against finished products containing any claimed API/salt/crystalline form.
Generic entry risk is highest for products using the same scaffold and listed salt anions; lower risk requires structural changes outside the enumerated aryl variants and/or selecting non-enumerated anions with careful solid-state control.

FAQs

Can a manufacturer avoid infringement by switching from hydrochloride to another salt?
Yes only if the selected anion is not within the enumerated X− list tied to the relevant dependent claims and the API still does not change other claim-critical structural elements.
Do “anhydride” claims cover accidental dehydration during manufacturing or storage?
If the dehydration product qualifies as “the anhydride of” the claimed compound under claim construction, infringement risk exists even if dehydration is not an intended final form.
How do crystalline tautomer claims affect solid-form design-around strategies?
They reduce the ability to avoid infringement merely by changing polymorph or isolating an alternative crystalline tautomer if that tautomer fits claim 11’s crystalline tautomer scope.
Is the aryl substitution scope open-ended?
No. The claim set you provided lists specific aryl patterns (methoxyphenyl; difluorophenyl variants; ethoxyphenyl; fluorophenyl). Substitutions outside those patterns fall outside the provided claim boundaries.
What is the biggest litigation leverage point for the patentee on this patent?
Demonstrating that an accused product uses one of the claimed benzo[1,4]oxazin-3-one derivatives and is formulated or exists as one of the enumerated acid addition salts or crystalline/anhydride forms.

References

United States Patent 7,491,719. Claims as provided in the prompt.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Germany	10 2004 024 454	May 14, 2004

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2005243469	⤷ Start Trial
Brazil	PI0511102	⤷ Start Trial
Canada	2562859	⤷ Start Trial
China	101133039	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,491,719

Summary for Patent: 7,491,719