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Patent landscape, scope, and claims: |
United States Patent 5,494,903: Scope, Claim Architecture, and Practical Patent-Barrier Analysis
What is US Patent 5,494,903 protecting in the US?
US 5,494,903 claims a broad genus of compounds defined by a single core scaffold with variable substituents, plus salt forms, plus compositions (pharmaceutical and veterinary). The independent claim (claim 1) is a structural Markush-style formula with tightly enumerated options for key groups, scaled by internal constraints on substituent combinations and a “R cannot have conflicting definitions” style proviso. Dependent claims (claims 2-98) narrow to narrower sub-genera (limited X/R/R5/R6 options) and then to a very large set of specific stereochemically defined exemplified compounds, with salts and specific acyl or sulfonyl substituents.
How broad is claim 1’s chemical space?
Claim 1 uses a central formula (depicted as “##STR223##” in your text) with substituent variables that, in practice, create a constrained but still very wide genus. The main “dial” parameters are X, R, and R (with sub-definitions for R4/R4’ and chain length n), plus a large enumerated set of allowable substituents on R4 and R4’ (amine, aryl, heteroaryl, aminoalkoxy, aminoxy, thio, sulfone, acyloxy, hydroxy, etc.), then salt/complex forms.
Key scope drivers in claim 1
-
X (attachment substituent on the scaffold nitrogen or equivalent position)
- X ∈ { amino, NR1R2, halogen }
- Halogen ∈ { Br, Cl, F, I }
- For X = NR1R2, R1 and R2 are individually enumerated and then further constrained by multiple “if” combinations (see below).
-
R (linker/functional group class)
- R ∈ { R4 (CH2)n CO-- , R4’ (CH2)n SO2-- }
- n ∈ 0-4
- Two large families:
- Carboxamide-acyl family: R = R4 (CH2)n CO--
- Sulfonamide-acyl family: R = R4’ (CH2)n SO2--
-
R4 vs R4’ substitution sets
- R4 is defined by an extremely large Markush list including:
- substituted C3-C6 cycloalkyl with cyano/amino/acyl substitution,
- substituted C6-C10 aryl with halo/alkoxy/trihaloalkyl/nitro/amino/cyano/alkoxycarbonyl/alkylamino/carboxy,
- multiple amino-acid like and protected amine like motifs,
- heterocycles (5- and 6-membered rings with N/O/S/Se heteroatoms),
- multiple carbonyl/acyloxy/alkoxycarbonyl groups,
- aryl oxy groups, thio groups, sulfonyl groups,
- hydroxy and mercapto,
- mono- or di-alkylamino (C1-C6) with explicit allowed alkyls,
- azacycloalkyl (C2-C5),
- alkylthio/arylthio/sulfonyl variants,
- and multiple “RaRb amino(C1-C4)alkoxy” and “RaRb aminoxy” variants where RaRb is enumerated.
- R4’ is similarly defined but with additional differences aligned with the sulfonyl branch.
-
R5 and R6 constraints (important “guardrails”)
- R5 ∈ { hydrogen, C1-C3 alkyl, C6-C10 aryl, C7-C9 aralkyl, or --(CH2)n COOR7 }
- R6 ∈ { hydrogen, C1-C3 alkyl, C6-C10 aryl, C7-C9 aralkyl, or --CH2)n (COOR7’) }
- Proviso:
- R5 and R6 cannot both be hydrogen
- Or R5 and R6 taken together are a specific linking pattern: --(CH2)2 W(CH2)2-- where W ∈ { (CH2)q q=0-1, --NH, --N(C1-C3)-alkyl, --N(C1-C4)alkoxy, oxygen, sulfur, or substituted congeners such as L/D proline, prolinate esters, morpholine, pyrrolidine, piperidine }.
Embedded combination constraints on X = NR1R2
Claim 1 does not allow arbitrary R1 and R2 pairing. It lists multiple conditional bands, for example:
- When X = NR1R2 and R1 = hydrogen, then R2 can be any of { methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl }.
- When R1 = methyl or ethyl, R2 is restricted to { methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl }.
- Additional conditional sets apply for R1 = n-propyl, R1 = 1-methylethyl, R1 = n-butyl, and R1 = 1-methylpropyl, each with narrower R2 lists.
This is a real scope limiter: even with wide individual definitions, the claim has “pairwise” constraints.
n range creates 5 discrete linker lengths per family
- For both R families (CO-- and SO2--) the chain length n = 0-4 is allowed (with later dependent-claim subsets narrowing n).
What do claims 2-5 do to the scope?
Claims 2-5 carve out narrower structural subranges:
Claim 2 (narrowed R/X subset)
- Tightens conditions where X and R are limited to specific R4/R4’ and n settings and limits R4 substituent options (for some R4 definitions, only select C6-C10 aryl substitution patterns are permitted at n=0 and only a smaller subset at n=1-4).
- Also narrows R4/R4’ aryl/alkoxy groups and permitted acyl/acyloxy, and restricts the allowed R5/R6 patterns to a similar constrained scheme with the “R5 and R6 cannot both be hydrogen” guardrail.
Claims 3-5 (salts and metal complexes)
- Claim 3: inorganic salts include hydrochloric, hydrobromic, hydroiodic, phosphoric, nitric, sulfate.
- Claim 4: organic salts include acetate, benzoate, citrate, cysteine and “other amino acids,” fumarate, glycolate, maleate, succinate, tartrate, alkylsulfonate, arylsulfonate.
- Claim 5: metal complexes include aluminium, calcium, iron, magnesium, manganese and “complex salts.”
These claims do not expand the core chemical structure, but they broaden legal coverage to salt and coordination forms of the genus.
What are claims 6-96 in practical scope terms?
Claims 6-96 are a high-density list of specific exemplified compounds with defined stereochemistry and explicit substituents on the R4/R4’ and acyl/sulfonyl moieties, plus many corresponding salts and free-base forms.
Structural pattern in the exemplified claims
Across claims 6-96, the recurring core is:
- A saturated polycyclic scaffold with multiple hydroxyls (“octahydro ... tetrahydroxy ... dioxo ... naphthacenecarboxamide” style naming).
- Two dimethylamino groups at fixed positions (“bis(dimethylamino)”).
- A variable substituent at a defined position via amido linkage to either:
- trifluoroacetyl, methoxyacetyl, benzoyl derivatives, sulfonyl/mesyl, tosyl derivatives, furanylcarbonyl, thienylcarbonyl, nitrobenzoyl derivatives, etc.
- or haloalkyl carbonyls such as chloroacetyl, bromoacetyl, bromo-oxoalkyl (e.g., “4-bromo-1-oxobutyl)amino”.
The claims differ mainly by which acyl/sulfonyl group is attached and which salts are present (sulfate, hydrochloride, hydrobromide, mono- vs di-salts, free base).
Examples of substituent classes actually covered in dependent claims
From your list, the exemplified set includes (non-exhaustive but directly evidenced):
- Acyl: trifluoroacetyl, methoxyacetyl, hydroxyacetyl, dimethylaminoacetyl, diethylaminoacetyl, aminoacetyl, chloroacetyl, bromoacetyl, benzoyl and substituted benzoyl (methoxybenzoyl, methylbenzoyl, fluorobenzoyl, pentafluorobenzoyl, trifluoromethylbenzoyl, aminobenzoyl, dimethylaminobenzoyl), formylamino, ethyl( and other) substituted carbonyl/acyl groups.
- Sulfonyl: phenylsulfonyl, chlorophenylsulfonyl, nitrophenylsulfonyl, thiophene(2-thienyl)sulfonyl, ethylsulfonyl, methanesulfonyl, phenylmethoxyacetyl style (acyl), and sulfonyl variants with heteroaryl or substituted aryl rings.
- Haloalkyl carbonyls: 2-bromo-1-oxopropyl, bromoacetyl, chloroacetyl.
- Protecting/side-chain variants: carbamic acid esters and multiple “carbamic acid methyl ester” style attachments (claim 22 and related).
- N-substituted acetamides: multiple examples where the amide nitrogen is morpholineacetamide, piperidineacetamide, pyrrolidineacetamide, imidazole-1-acetamide, azetidineacetamide.
This matters for freedom-to-operate because these are the “landmarks” the patent likely expects you to land on if your R group or R4/R4’ substituent is within the described pattern.
What do claims 97-98 cover?
- Claim 97: pharmaceutical composition comprising a claim 1 compound with a pharmaceutically acceptable carrier.
- Claim 98: veterinary composition comprising a pharmacologically effective amount with a pharmaceutically acceptable carrier.
These are standard formulation claims that expand infringement to dosage forms and non-API embodiments (subject to the same compound coverage).
Claim construction risk points for competitors (where enforcement pressure concentrates)
1. The R5/R6 guardrail blocks “trivial” alternatives
The proviso “R5 and R6 cannot both be hydrogen” prevents competitors from arguing they only need a hydrogen/hydrogen variant. If your target compound relies on both being hydrogen, it is outside the literal claim 1 coverage as written.
2. The X = NR1R2 pairwise constraints are non-trivial
Because claim 1 uses conditional statements for allowed R1/R2 pairings, a competitor can design around by selecting a disallowed R1/R2 pairing even if both R1 and R2 are separately listed. From an enforcement perspective, this shifts validity and infringement analysis from “is R1 allowed” to “is the pairing allowed.”
3. The “R family” choice is bifurcated (CO-- vs SO2--)
A competitor may use a different functional group identity (carboxylate-type vs sulfone-type) that maps to CO-- vs SO2-- and then choose n and R4/R4’ accordingly. This reduces ambiguity: infringement depends on whether the compound’s functional group sits in the CO-- family or SO2-- family and matches the corresponding R4 or R4’ substitution sets.
Patent landscape implications (US enforceability posture)
Because your prompt provides only the claims text and not the specification or prosecution history, the landscape conclusions must be tied to the claim architecture you provided.
What the patent is likely doing strategically
- Claim 1 is a broad genus with many enumerated substituents. This is typical for defending a chemical class while accommodating multiple final products (e.g., different prodrugs, different acyl/sulfonyl side chains, different salt forms).
- Claims 6-96 provide a long list of specific stereodefined examples and salts. This supports:
- stronger enforcement against known marketed or lead compounds that match the exemplified variants,
- and a broader argument that the genus is enabled and supported by actual embodiments.
What competitors should treat as high-risk design space
Based on the enumerated exemplars:
- Benzoyl and substituted benzoyl at the defined “amino acyl” position (chloro, fluoro, methoxy, nitro, trifluoromethyl, pentafluoro, aminobenzoyl, dimethylaminobenzoyl).
- Sulfonyl groups (phenylsulfonyl, chlorophenylsulfonyl, nitrophenylsulfonyl, methanesulfonyl, benzenesulfonyl substituted with halo and nitro patterns, and thiophene-derived sulfonyl).
- Haloacetyl and bromo/oxoalkyl derivatives (chloroacetyl, bromoacetyl, bromo-oxoalkyl).
- Aminoacetyl and substituted aminoacetyl derivatives (dimethylaminoacetyl, diethylaminoacetyl, aminoacetyl, hydroxyacetyl, formylamino, and other acylated amino variants).
- Multiple salt forms (sulfate, hydrochloride, hydrobromide, mono/dihydrochloride, free base).
Scope summary table (what is included vs structurally restricted)
| Claim element |
Allowed scope in claim 1 (per your text) |
Built-in restriction / practical effect |
| X |
amino OR NR1R2 OR halogen (Br/Cl/F/I) |
For NR1R2, allowed R1/R2 pairings are conditional (not any combination). |
| NR1R2 substituents |
R1 ∈ {H, Me, Et, n-Pr, i-Pr, n-Bu, i-Bu}; R2 ∈ enumerated alkyl set |
Conditional tables narrow R2 for each R1 choice. |
| R family |
R = R4(CH2)nCO-- OR R = R4’(CH2)nSO2-- |
Two distinct families; mapping to CO vs SO2 matters. |
| n |
0-4 |
Dependent claims narrow n for certain R4 definitions. |
| R5/R6 |
H, C1-C3 alkyl, C6-C10 aryl, C7-C9 aralkyl, or esterified “COOR” patterns |
“R5 and R6 cannot both be hydrogen.” Also allows a tether form where R5 and R6 together form --(CH2)2W(CH2)2-- with W list. |
| Salts |
inorg: HCl, HBr, HI, phosphoric, nitric, sulfate; org: acetate, benzoate, citrate, cysteine/amino acids, fumarate, glycolate, maleate, succinate, tartrate, alkyl/aryl sulfonates |
Expands infringement to salt forms of covered compounds. |
| Metal complexes |
Al, Ca, Fe, Mg, Mn |
Expands infringement to coordination complexes of covered structures. |
| Compositions |
pharmaceutical + veterinary |
Expands to formulated dosage products carrying covered compounds. |
Key Takeaways
- US 5,494,903 is a structural genus patent with claim 1 as the primary barrier: it covers a wide set of substituted compounds built on a fixed scaffold with enumerated substituent options and explicit pairwise constraints on X = NR1R2 and a hard guardrail on R5/R6.
- Enforcement leverage concentrates in claims 6-96, which list many stereodefined exemplified compounds with explicit acyl and sulfonyl substituents (benzoyl derivatives, haloacetyl derivatives, aminoacetyl derivatives, phenylsulfonyl and substituted aryl/heteroaryl sulfonyl variants) plus salts.
- Coverage extends beyond API to salts, metal complexes, and compositions (claims 3-5, 97-98). This increases the number of legally infringing product forms competitors must clear.
FAQs
1) Does claim 1 cover both carboxyl and sulfonyl side-chain variants?
Yes. Claim 1 allows R = R4(CH2)nCO-- and R = R4’(CH2)nSO2--, with n = 0-4, and each branch has its own R4/R4’ substitution set.
2) Can competitors select any listed R1 and any listed R2 for X = NR1R2?
No. Claim 1 provides conditional “when R1 = … then R2 ∈ …” rules, so the R1/R2 pairing is constrained.
3) Is the hydrogen/hydrogen case for R5 and R6 allowed?
No. Claim 1 includes the proviso that R5 and R6 cannot both be hydrogen.
4) What product forms are explicitly covered beyond the free base?
The claims expressly cover inorganic and organic salts (claims 3-4) and metal complexes (claim 5), plus pharmaceutical and veterinary compositions (claims 97-98).
5) Do claims 6-96 matter if a competitor targets a non-exemplified variant?
Yes. They are not required for literal infringement because claim 1 provides the genus. But claims 6-96 are critical for enforcement planning because they identify concrete stereodefined, substituent-specific embodiments that likely track actual compounds.
References
[1] United States Patent 5,494,903 (claim text provided in prompt).
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