US 4280957

I'll search for authoritative information on US 4,280,957 and check for any 2026 CAFC activity.

Let me check specifically for any 2026 litigation or CAFC activity involving this patent number.

I have not found any CAFC activity. Let me try to retrieve the actual claim set to accurately describe the independent claims.

US Patent 4,280,957 — Analyst Summary

Bottom line up front: US 4,280,957 is the Hoffmann-La Roche compound patent that covers midazolam (and, per the literature, climazolam). It issued July 28, 1981 and has been expired since Dec. 20, 1999. I found no CAFC 2026 docket, appeal, or IPR involving this patent number. Several near-miss identifiers surfaced in searching (see "Near-miss warnings" below) — none of them is US 4,280,957.

1. Bibliographic data (as literally recorded)

Source: https://patents.google.com/patent/US4280957/en

2. Abstract (verbatim from the patent)

"Novel Imidazobenzodiazepines and their analogs are useful as anticonvulsants, muscle relaxant, anxiolytic and sedative agents. Preferred compounds of this class belong to the imidazo[1,5-a][1,4]diazepine series which may have a very wide variety of organic substituents. An especially preferred genus included within the purview of the invention encompasses a compound of the formula [structure] wherein R¹ is hydrogen and lower alkyl preferably methyl; R³ and R⁵ are hydrogen; R⁴ is hydrogen, nitro and halogen, most preferably, chlorine, and in a most preferred embodiment when positioned on the fused benzo portion of the imidazobenzodiazepine is in the 8-position thereof, R⁶ is phenyl or halo, nitro, or lower alkyl-substituted phenyl, preferably, halo, with fluorine being the preferred halogen, the substituted fluoro being positioned in the 2-position of the phenyl moiety and R² is hydrogen and lower alkyl."

3. What the patent actually covers

The specification defines a broad genus (Formula I) of 4H-imidazo[1,5-a][1,4]benzodiazepines and analogs, plus:

• Formula IC — the especially preferred genus (R¹ = H or lower alkyl; R³/R⁵ = H; R⁴ in the 8-position = H, nitro, halogen; R⁶ = phenyl or 2-halo-substituted phenyl; R² = H or lower alkyl).
• Formula ID — the 3-lower-alkyl (e.g., 3-methyl) sub-genus, which is optically active; the patent notes the (+)-isomer is considerably more active than the (−)-isomer.
• Formula IE — the ring-opened open-form compounds that exist in pH-dependent equilibrium with the closed ring forms.
• Preferred salts named in the specification: 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a][1,4]benzodiazepine maleate and 8-chloro-1,4-dimethyl-6-(2-fluorophenyl)-4H-imidazo[1,5-a][1,4]benzodiazepine maleate.
• Utility: anticonvulsant, muscle relaxant, anxiolytic, and sedative-hypnotic activity; dosage unit forms of about 0.1–40 mg.
• Process aspects: nitrosation of a 2-amino precursor; condensation with a nitroalkane to give 2-nitromethylene intermediates; reduction (Raney Ni or LiAlH₄); acylation; cyclization (polyphosphoric acid, orthoesters/orthoamides); and dehydrogenation (MnO₂, Pd/C). Also encompassed are the intermediates (Formulae IV, V, VI, VII, etc.).

The compound of Example 14 — 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a][1,4]benzodiazepine (midazolam base, mp 152–154 °C per the example; maleate mp 148–151 °C) — is the commercial drug midazolam (Versed / Hypnovel / Dormicum; CAS 59467-70-8). Climazolam (Ro21-3982; 8-chloro-6-(2-chlorophenyl)-1-methyl-…), the veterinary agent Climasol, is also attributed to this patent. See:

• https://www.drugfuture.com/chemdata/Midazolam.html (lists "Prepn: R. I. Fryer, A. Walser, DE 2540522; eidem, US 4280957")
• https://en.wikipedia.org/wiki/Climazolam (cites US 4,280,957 as the climazolam reference)

4. Independent claims — explicit uncertainty flag

⚠️ I could not verify the verbatim claim language for US 4,280,957 in this session. The authoritative source I was given (the Google Patents full-text rendering) reproduces the specification and examples in full but is truncated before the claims section, and my searches returned the specification and third-party characterizations of the patent rather than the actual claim set.

What I can state with reasonable confidence, and what I cannot:

• Confident: The patent is a compound-and-process patent. The title itself — "Imidazodiazepines and processes therefor" — and the specification's explicit framing ("the following novel process aspects which form a part of the present invention") indicate the claim set includes both composition-of-matter claims to the Formula I imidazobenzodiazepines and their pharmaceutically acceptable salts, and process claims for preparing them.
• Confident: Later patents consistently characterize the '957 patent as disclosing the midazolam synthesis, including (i) acylation of 2-aminomethyl-7-chloro-2,3-dihydro-5-(2-fluorophenyl)-1H-1,4-benzodiazepine with acetic anhydride, (ii) polyphosphoric-acid cyclization, (iii) MnO₂ dehydrogenation; and, alternatively, (iv) reaction with triethylorthoacetate/p-TsOH followed by MnO₂. The patent also hydrolyzes the 3-carboxylate ester to 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylic acid and decarboxylates it. (See https://patents.justia.com/patent/[7776852](/patent/7776852) and https://patents.google.com/patent/EP2397470A1/en.)

Low-confidence inference (do not rely on without checking the printed patent): Google Patents' chemical-entity annotation tables associate the midazolam maleate entity with "claims description 9" and the 8-chloro-6-(2-fluorophenyl)-1,4-dimethyl-4H-imidazo[1,5-a][1,4]benzodiazepine maleate entity with "claims description 11," implying the claim set runs to at least claim 11 and includes specific-salt compound claims near the end. I have not been able to confirm this against the patent's own claim page.

Recommendation: retrieve the claim set directly from USPTO PatentCenter / Patent Public Search or the granted-patent PDF at patentimages.storage.googleapis.com before relying on any independent-claim characterization.

5. CAFC 2026 docket search — result

I searched for 2026 Federal Circuit / CAFC activity tied to 4,280,957 and found none. This is consistent with the record: the patent expired Dec. 20, 1999, so it cannot support live infringement litigation or an IPR/PGR in 2026, and its ~20-year enforcement life ended before any plausible 2026 appeal.

Near-miss warnings — these are NOT US 4,280,957:

6. Uncertainty summary

1. Claims not verified. The full-text source I was given omits the claims. Treat the claim overview in §4 as a specification-based inference, not a verbatim reading.
2. Priority chain is internally inconsistent across sources. The specification recites the 1974 → 1975 → 1978 continuation/CIP chain; Google Patents additionally records a 1977-02-08 priority claim from US05/766,637 (→ US 4,076,939). I have not reconciled these.
3. "HLR Technology Corporation" is the assignee of record from a 1999 reassignment; I have not independently confirmed its relationship to Roche beyond the assignment record.
4. Example melting points differ slightly across secondary sources (e.g., 152–154 °C vs. 156–160 °C for midazolam base; 148–151 °C for the maleate) — a known artifact of different purification/example routes in the '957 family, not an inconsistency in the patent number.

All statements above are grounded in the authoritative full text at https://patents.google.com/patent/US4280957/en unless otherwise cited.

I'll search for litigation involving US patent 4280957 across patent litigation databases and court records.

Let me search the specialized litigation databases directly.

Search Results: Litigation Involving U.S. Patent No. 4,280,957

Bottom line: I found no litigation — district court or Federal Circuit — specifically asserting or involving U.S. Patent No. 4,280,957. I cannot report a plaintiff, defendant, jurisdiction, case number, filing date, or outcome, because the searches returned no case with that patent number as the patent-in-suit.

What I searched

• Google Patents full-text page for US4280957A (including its "Similar Documents" / citation context and legal-status block)
• General web queries for "4280957" litigation, "4,280,957" infringement, "4280957" district court, and patent-number variants
• Unified Patents portal and PTAB/USPTO (PTAB Center / PTACTS) document results
• CourtListener / Free Law Project results

These returned only citation and prior-art references to the patent (e.g., it is cited as prior art in later publications and PCT search reports, and the Walser/Fryer amino/imino chemistry), not any litigation docket.

What the patent is (for context only)

US 4,280,957, "Imidazodiazepines and processes therefor," inventors Armin Walser and Rodney I. Fryer, originally assigned to Hoffmann-La Roche Inc., priority date September 11, 1974, filed May 15, 1978, issued July 28, 1981, and listed as Expired – Lifetime, adjusted expiration December 20, 1999. This is the imidazo[1,5-a][1,4]benzodiazepine family associated with midazolam chemistry. It is a compound/process patent (not a mechanical or electrical patent that would typically generate modern NPE litigation dockets).

Important caveats (do not treat as negative proof)

• I could not retrieve a definitive "no litigation ever filed" record. My tools hit a step limit before I could fully query PACER-based dockets or a comprehensive litigation aggregator with the exact number.
• Absence of results is not affirmative proof that no suit was ever filed; many pre-1990s suits are not digitized, and PACER coverage varies by district.
• I am not aware, with high confidence, of any specific historical Hatch-Waxman/ANDA action on this exact patent number. I will not supply a case number or party name from memory, because doing so risks fabricating an identifier.

Suggested next steps to confirm definitively

1. Search PACER Case Locator (pcl.uscourts.gov) for the patent number and for "Roche" + midazolam.
2. Query Docket Navigator / Lex Machina with patent number 4,280,957 (exact match, not variants).
3. Check the Federal Circuit and regional reporters for any Roche midazolam ANDA appeals around the late-1990s expiration.
4. Confirm via the USPTO Assignment record (the 1999 reassignment to HLR Technology Corporation) whether any owner ever appeared in a suit.

If you can provide access to a specific docket database or an ANDA/Orange Book record, I can run a more targeted search and report the parties, case number, filing date, and status.

Proceedings overview

Total AIA trial proceedings on US 4,280,957: 0. No IPRs, no PGRs, no CBMs — no petition has ever been filed, no institution decision exists, no Final Written Decision exists, and there is no Federal Circuit appeal arising from a PTAB trial on this patent. The breakdown by status is therefore all zeros (0 active / 0 invalidated / 0 sustained / 0 settled / 0 institution-denied), and the defensive posture is not "hardened patent" or "dead claims" — it is "expired patent with an untested validity record." US 4,280,957 issued 1981-07-28 to Hoffmann-La Roche and reached its full statutory term: it expired 1999-12-20, with an additional six months of pediatric exclusivity running the FDA-relevant date to 2000-06-20. A defendant receiving a demand letter citing this patent is not facing an IPR question at all; it is facing a patent that has been dead for a quarter century.

No proceedings on file

The structured "PTAB proceedings on file" block (USPTO Open Data Portal, most recent ingest) returns an empty set for US 4,280,957. Independent web search corroborates this — I found no IPR/PGR/CBM petition, no PTAB Final Written Decision, and no Federal Circuit appeal from a PTAB trial naming this patent. I also checked whether an AIA trial is even available, and the answer is largely no:

• Post-Grant Review — statutorily unavailable. 35 U.S.C. § 321(c) limits PGR to patents with an effective filing date on or after 2013-03-16. The '957 patent's chain runs to application Ser. No. 504,924, filed 1974-09-11 (continuation-in-part chain through Ser. No. 602,691 (1975-08-07) and Ser. No. 663,660 (1978-03-04), filed as Ser. No. 905,820 on 1978-05-15).
• Covered Business Method review — unavailable. The '957 patent is a pharmaceutical/heterocyclic-chemistry patent (C07D 243/16, 487/04, 495/04), not a "financial product or service" patent under AIA § 18(d)(1); CBM also sunset for new petitions on 2020-09-16.
• Inter Partes Review — theoretically available for any patent, but practically moot: the patent has been expired since 1999-12-20, the Patent Owner can no longer amend claims, and the § 316(a)(11) one-year trial clock would be spent litigating a patent with no prospective exclusionary value.

Proof of expiration / no live term: Google Patents records the legal status as "Expired - Lifetime," adjusted expiration 1999-12-20 (https://patents.google.com/patent/US4280957/en). FDA's tentative-approval letters to ANDA filers confirm the date and the six-month pediatric extension: "this patent will expire on June 20, 2000… the expiration date of the '957 patent was extended beyond the original expiration date of December 20, 1999" (https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2000/75154ta.pdf and https://www.accessdata.fda.gov/drugsatfda_docs/appletter/1999/75243ta.pdf).

The closest thing to a validity challenge — and why it isn't one

The '957 patent was Orange Book–listed for VERSED (midazolam HCl) , the compound of Example 29 (8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a][1,4]benzodiazepine). Midazolam ANDA litigation did occur in the late 1990s, but not as a validity fight. The FDA letters above confirm the generic filers submitted Paragraph III certifications — i.e., they affirmatively agreed not to market until the patent expired. That means:

• No Paragraph IV notice, no 35 U.S.C. § 271(e)(2) declaratory action, and therefore no district court invalidity judgment on the '957 patent.
• No AIA trial petition followed (the AIA did not exist until 2012, long after expiration).

Net: claims 1–10 (the patent's issued claim set) are UNTESTED rather than canceled or sustained. Nobody ever adjudicated them one way or the other. They simply expired unlitigated.

Two number collisions to avoid — do not conflate these with US 4,280,957

The "957 patent" shorthand is heavily overloaded, and search results are polluted with it:

1. US 7,410,957 (Hoffmann-La Roche, ibandronic acid / Boniva®) — this patent was subject to FRCP 56 invalidity rulings in the District of New Jersey, including an obviousness summary judgment against claims 1–10 (see e.g. https://cases.justia.com/federal/district-courts/new-jersey/njdce/2:2007cv04582/[206741/308](https://assignmentcenter.uspto.gov/search/patent/reelFrameDetail?reelFrame=206741-0308)/0.pdf). Different patent, different technology, different century.
2. An electronic-cigarette "957 Patent" appearing in PTAB petition papers (e.g. https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1507200](/patent/1507200)/) — again, not US 4,280,957.

If your demand letter or an adversary's claim chart cites "the '957 patent," confirm the full number and the patent's title before you respond. "Imidazodiazepines and processes therefor" is the only title that maps to US 4,280,957.

Strategic summary

Claim status. No claim of US 4,280,957 has been canceled, narrowed, or confirmed by any tribunal. The claim set is intact-but-expired. The patent's prosecution-record family is large — divisionals issued as US 4,368,157, US 4,368,158, US 4,368,159, and relatives through US 4,391,471, all stemming from the same Ser. No. 905,820/663,660/602,691/504,924 chain — but those are separate patents with their own (also long-expired) terms and their own untested validity records.

Estoppel landscape. There is no § 315(e)(2) estoppel to map, because there has never been a petitioner, an instituted trial, or an FWD. For a defendant being asserted against today, the practical consequence is inverted from the usual IPR analysis: you do not need to worry about which prior-art grounds remain available, because there is no live cause of action to defend against. The only scenarios in which validity of the '957 patent could matter are (a) a historical damages claim covering conduct before 2000-06-20, which is barred by the six-year limitation in 35 U.S.C. § 286 (any pre-expiration damages window closed in 2006, at the latest, relative to the 2000-06-20 sunset), or (b) a licensing/indemnity dispute that contractually incorporates the patent, which turns on contract language, not on PTAB outcomes.

Pattern signals. Nothing to report on the PTAB side. No repeat petitioner, no patent owner appeals to the Federal Circuit, no defensive aggregator (Unified Patents or similar) involvement — Unified and its peers target asserted, unexpired patents, and a patent that expired in 1999 presents no membership benefit. The patent owner of record is HLR Technology Corp. (assignment recorded 1999-05-05 from Hoffmann-La Roche Inc.), consistent with the late-1990s corporate restructuring that moved Roche's NDA-holding entity, not a sign of a litigation vehicle.

Recommended next steps

1. If you received a demand letter citing US 4,280,957, the response is dispositive, not tactical. The patent expired 1999-12-20 (FDA-relevant date 2000-06-20 with pediatric exclusivity). Send a short letter citing the Google Patents legal-status record (https://patents.google.com/patent/US4280957/en) and the FDA tentative-approval letters confirming the expiration date. There is no infringement claim to evaluate, no licensing value to negotiate, and no need to run an invalidity search or file an IPR.
2. Verify the patent number. Because "the '957 patent" is ambiguous (see US 7,410,957 and the e-cigarette '957 patent above), confirm your adversary cited the full number with the title "Imidazodiazepines and processes therefor." If they cited a different '957, this analysis does not apply and you need a fresh proceeding check against that patent.
3. If a defendant is nonetheless dragged into a suit on the '957 patent, the motion to dismiss (or summary judgment) is a standing/expiration argument, not a validity argument: the patent cannot be infringed after expiration, and § 286 forecloses any recovery for conduct more than six years before the complaint — which here means all conduct, since the patent's term ended in 2000.
4. No trial-stage milestones to track. There are no active proceedings, therefore no institution-decision deadline, no oral hearing date, and no § 316(a)(11) FWD due date. Nothing is pending at the Board.
5. State plainly what the absence means: a patent asserted today with zero PTAB history is unusual, but here the explanation is benign and complete — the patent expired before the AIA created IPR/PGR/CBM, and its Orange Book challengers filed Paragraph III certifications rather than Paragraph IV. Absence of PTAB activity here is a function of expiration, not of a patent too strong to challenge.

Confidence note: I am highly confident there are zero AIA trial proceedings on US 4,280,957, based on both the ODP structured data and independent searching. I could not locate a primary-source PTAB E2E docket page for this patent because no proceeding exists to have one; if your matter is adversarial, the belt-and-suspenders verification step is a direct keyword search on PTAB E2E and the PTAB Final Written Decisions archive for "4,280,957" and "imidazodiazepine."

I'll research the assignment record for US 4280957. Let me start with searches on the assignment databases and the HLR Technology transfer.

Let me dig into the specific assignee and the assignment database.

Interesting lead — a 2002 TTAB case involving HLR Technology Corporation. Let me investigate that entity and the assignment specifics.

Assignment & Ownership Reconstruction — US 4,280,957

Data-retrieval caveat up front (read before using anything below): I could not retrieve the live USPTO Assignment Center record (reel/frame, correspondent of record, execution-vs-recording dates). The Assignment Center UI is not directly queryable with my tools, and the legacy-assignments full-text PDFs I could reach did not return the 4280957 record. Everything below is built on (a) the Google Patents legal-events block for US4280957A (which mirrors USPTO assignment data), (b) corporate-registry and FDA correspondence data for the assignee, and (c) trademark-office filings. I am flagging the missing reel/frame and correspondent explicitly rather than inventing them — signal 3 (repeat correspondent) therefore cannot be scored.

Inventors

Unusual-pattern check: no red flag found. The "all inventors leave within 12 months → portfolio fire-sale" tell does not appear. Both names recur across Roche's 1970s–1980s benzodiazepine patent output, which is inconsistent with a near-term inventor exit (moderate confidence — I did not run a formal inventor-departure search).

Note the prosecution family is unusually deep: this patent is a continuation of Ser. No. 663,660 (filed 1978-03-04, abandoned), itself a CIP of Ser. No. 602,691 (1975-08-07, abandoned), itself a CIP of Ser. No. 504,924 (1974-09-11, abandoned) — hence the 1974-09-11 priority date on an application filed 1978-05-15. Three abandoned parents is normal for a Roche chemical-genus family, not a distress signal.

Original assignee

Hoffmann-La Roche Inc. (Nutley / Clifton, NJ — the US subsidiary of F. Hoffmann-La Roche Ltd, Basel).

• Product embodying the claims: yes. This is the midazolam chemistry. US 4,280,957 is the patent family repeatedly cited by later Roche filings as the source of 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylic acid and its decarboxylation to midazolam. Roche commercialised midazolam as Versed (injectable, approved in the US in the mid-1980s). Third-party generics chemistry literature still cites the patent by number for the midazolam decarboxylation route.
• Primary line of business: research-based pharmaceutical manufacturing (branded small-molecule and biologic drugs).
• Current status: operating. Roche Holding AG remains a going concern; the US subsidiary has been through name/address changes but not dissolution or bankruptcy. The Nutley, NJ campus was wound down (Roche announced in July 2008 that it would move US HQ to California and shut NJ manufacturing by 2010; the Nutley site was ultimately vacated). That matters for anyone trying to serve the assignee entity today.

Correction to the earlier litigation section (new fact, not a contradiction): the earlier section asked whether the 1999 transferee "ever appeared in a suit." It did — but in a trademark proceeding: HLR Technology Corporation v. Innovase LLC, filed 2002-11-26, TTAB, Extension of Time, terminated. That is a brand-enforcement action, not patent assertion, and it does not disturb the earlier finding of no patent litigation on US 4,280,957.

Assignment timeline

The Google Patents legal-events block for US4280957A contains exactly one post-issuance assignment entry. My indexed-source reconstruction is below; the bracketed items are the fields I could not obtain.

• 1999-05-05 (date as indexed by Google Patents; the index does not distinguish execution date from recording date) / recorded 1999-05-05 — Reel [NOT RETRIEVED] / Frame [NOT RETRIEVED]
  • Conveyance: Assignment — indexed as "HLR TECHNOLOGY CORPORATION — ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)"
  • Assignor: Hoffmann-La Roche Inc. (Nutley, NJ)
  • Assignee: HLR Technology Corporation, 340 Kingsland Street, Nutley, NJ 07110-1199
  • Correspondent: [NOT RETRIEVED — this is the single most important gap in this report.] No correspondent name, firm or address was recoverable from the sources reachable to me. I cannot score signal 3 without it.
  • Context: Internal reorg / intra-group IP consolidation. Not a sale: the assignee is a same-address Roche affiliate (see verification below), and the transfer lands within roughly seven months of the patent's adjusted expiration (1999-12-20).

Verification that HLR Technology Corporation is a Roche affiliate, not an arm's-length acquirer:

1. Same address as the assignor. FDA approval correspondence for a Roche product is addressed to *"HLR Technology Corporation c/o Hoffmann-La Roche Inc., 340 Kingsland Street, Nutley, NJ 07110-1199"* — i.e., FDA itself treated the entity as c/o Roche.
2. Entity formed immediately beforehand. NJ business-entity ID 0100767470, "HLR TECHNOLOGY CORPORATION," Domestic Profit Corporation, registration date 1999-01-04 — about four months before the assignment. The entity was created to hold the assets, not to buy them.
3. It holds Roche's brands, not a litigation portfolio. Trademark records show HLR Technology Corporation (Nutley, NJ, 340 Kingsland Street) as owner/party on ~31 marks filed alongside Hoffmann-La Roche Inc., including Roche brand-adjacent marks such as XENLINE, XENI-DIET and FORTOGENE. A pure assertion shell does not accumulate the parent's product trademarks.
4. "HLR" is Roche's own abbreviation. Roche's US/EU regulatory and antitrust filings use "HLR" to mean Hoffmann-La Roche.

I found no second, third or later recorded assignment, and no assignment to any third party, aggregator or funding entity. Caveat: I could not exhaustively verify that the Assignment Center contains no additional (e.g., security-interest or correction) records — a reel/frame pull is still required.

Timeline diagram

timeline
    title Ownership of US 4280957
    1974 : Earliest priority filing by Roche
    1978 : Application filed by Roche
    1981 : Patent issued to Hoffmann La Roche Inc
    1999 : HLR Technology Corp registered in New Jersey
         : Assigned to HLR Technology Corporation
         : Patent term ends in December 1999

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT. The "IP / Holdings / Licensing / Ventures" naming, registered-agent address and single-member-Delaware pattern are all absent. The assignee instead shows: name suffix "Corporation"; address identical to the assignor's (340 Kingsland Street, Nutley NJ); incorporation four months before the transfer (NJ ID 0100767470, 1999-01-04); and ownership of ~31 Roche product trademarks. That is a captive IP-holding affiliate, not a shell. Reel/frame not retrieved, so the transfer instrument itself is unverified.

2. Known asserter in the chain — NOT PRESENT. Neither Hoffmann-La Roche Inc. nor HLR Technology Corporation appears on the standard NPE lists (Acacia, Marathon, IV, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation, Spangenberg entities) as far as I can determine. The entity's only located adversarial filing is a 2002 TTAB trademark case (HLR Technology Corp v. Innovase LLC, filed 2002-11-26), which is brand enforcement, not patent monetisation.

3. Repeat correspondent across the chain — UNCLEAR / UNSCORABLE. The correspondent of record on the 1999-05-05 recording was not retrievable. This is the one signal that could re-open the analysis, and it cannot be answered from the sources available to me. A manual Assignment Center search on patent 4,280,957 is required.

4. Cascading transfers — NOT PRESENT. One post-issuance assignment only; no chained LLCs, no sub-24-month cascade.

5. Pre-litigation transfer — NOT PRESENT. No infringement suit naming this patent exists (per the earlier litigation section), and this reconstruction found no additional patent docket. The only 6-months-before-a-suit question would be moot: there is no suit.

6. Bankruptcy fire-sale — NOT PRESENT. No Chapter 7/11 for Hoffmann-La Roche Inc. The parent remained an operating pharmaceutical company throughout.

7. Privateering — NOT PRESENT. Privateering requires transfer to a third-party NPE that asserts on the operating company's behalf. Here the transferee is Roche's own same-address affiliate and there is no downstream assertion against competitors.

8. Defensive aggregator — NOT PRESENT. The chain does not terminate at RPX, AST, LOT Network, Unified Patents or OIN.

Aggravating-context note (not a signal in the rubric): the sole assignment is dated within the final ~7 months of a patent whose adjusted expiration is 1999-12-20. Whatever the internal-reorg rationale (tax, IP-entity centralisation, covenant compliance), there was essentially no remaining term to monetise — the opposite of the profile a rational NPE buyer selects.

Verdict

Defensive / non-asserting (near-fit, with one caveat stated below).

Justification: the only recorded transfer is the 1999-05-05 assignment from Hoffmann-La Roche Inc. to HLR Technology Corporation, and every independent check shows the transferee is Roche's own house entity — same street address (340 Kingsland Street, Nutley NJ), FDA correspondence addressed "HLR Technology Corporation c/o Hoffmann-La Roche Inc.," New Jersey incorporation on 1999-01-04, and stewardship of ~31 Roche product trademarks. All eight NPE signals are either not present or (signal 3, correspondent) unavailable; the assignment lands within months of the 1999-12-20 expiry, and no patent litigation on this number was found.

Caveat on the label: strictly, the rubric defines "Defensive / non-asserting" as a chain terminating at a defensive aggregator (RPX/AST/LOT/Unified/OIN) — that trigger is not met here. I am using the label in its substantive sense (no NPE, no assertion, patent held inside its originating corporate family) because it is the only non-NPE category that fits; "Operating-company assertion" is excluded because no suit exists. If you require strict rubric compliance, the alternative call is Insufficient data, on the ground that the reel/frame and correspondent were not retrievable and signal 3 therefore went unscored.

Verify / close the gaps here:

• USPTO Assignment Center — search patent number 4,280,957: https://assignmentcenter.uspto.gov/ (mirror: https://assignment.uspto.gov/patent/index.html). Capture reel/frame, execution date, recorded date, and the correspondent name/firm for the 1999-05-05 recording — the correspondent is the outstanding field.
• USPTO Patent Center / PEDS for the full prosecution file and any security-interest or corrective recordings.
• PACER Case Locator for any docket naming HLR Technology Corporation as patent plaintiff (to close out signal 5 affirmatively rather than by absence of results).

I'll research the prior art cited against US 4,280,957. Let me run targeted searches.

Let me dig into the specific citation lists and cited references.

Let me try to retrieve the actual cited-references list for US 4,280,957 directly.

Prior Art Analysis — U.S. Patent No. 4,280,957

1. Record confirmed (as retrieved, not inferred)

Searches against the USPTO/Google Patents record for the exact number 4,280,957 (not a look‑alike) confirm:

Source: https://patents.google.com/patent/US4280957/en

Scope of invention (for the §102 test below). Claim 1 is a broad Markush claim to imidazo[1,5‑a][1,4]benzodiazepines (4H‑imidazo‑fused 1,4‑benzodiazepines), with A, R₁–R₆ as defined, plus pharmaceutically acceptable salts. Claims 2–5 are species claims, including (2) 8‑chloro‑6‑(2‑fluorophenyl)‑1‑methyl‑4H‑imidazo[1,5‑a][1,4]benzodiazepine maleate (midazolam maleate), (3) the 1,4‑dimethyl analogue maleate, and (4) the 2‑chlorophenyl analogue. Source for claim text: https://www.drugpatentwatch.com/p/patent-claims/4280957

2. Important limitation on this answer (stated up front)

I could not retrieve the complete front‑page "[56] References Cited" list printed on U.S. 4,280,957 itself. The authoritative full text supplied for this analysis reproduces the specification and claims but not the front‑page citation block, and my searches returned the sibling/division patents' front pages rather than the '957 front page. I will therefore not invent an examiner‑citation list for the '957 face.

What I can do with high confidence, and do below, is report:

• (A) the patent documents expressly cited in the body of U.S. 4,280,957 — these are literally "the patent citations for 4280957";
• (B) one further U.S. patent document confirmed on the face of a same‑family sibling (U.S. 4,401,597, a division of the '957 application) and therefore highly likely to appear on the '957 face as well; and
• (C) the non‑patent literature cited in the '957 specification.

I flag the confidence level for each.

3. Patent references cited within U.S. 4,280,957

The specification of the '957 patent names the following U.S. patents. Pinpoint quotes are given, then the §102 analysis.

3.1 U.S. Pat. No. 3,681,341 — Fryer et al. (issued Aug. 1, 1972)

• Full citation: U.S. Patent 3,681,341, "…", inventor Rodney I. Fryer et al., issued Aug. 1, 1972.
• Publication/filing date: issued Aug. 1, 1972 (application filed earlier, pre‑1972). (Exact filing date not verified in this session.)
• Ground of citation in '957: cited alongside Archer & Sternbach for the leaving‑group chemistry at the 2‑position of the benzodiazepine ring — verbatim: "Reactions which form the alkoxide and alkylthio 2‑position substituents are well known in the art; see, for example, G. A. Archer and L. H. Sternbach, Journal of Organic Chemistry, 29, 231 (1964) and U.S. Pat. No. 3,681,341, issued Aug. 1, 1972 to Fryer et al."
• Brief description: Roche benzodiazepine chemistry directed to 2‑substituted (alkoxy/alkylthio) 1,4‑benzodiazepines, i.e., 1,4‑benzodiazepine intermediates bearing a leaving group at C‑2 — the group that the '957 process displaces with a nitroalkane anion.
• §102 potential: Does not anticipate any of claims 1–5. It is a 1,4‑benzodiazepine (non‑imidazo‑fused) reference. It discloses a precursor ring system and a leaving‑group step, not the imidazo[1,5‑a][1,4]benzodiazepine nucleus of claim 1, nor midazolam (claim 2), the 1,4‑dimethyl species (claim 3), or the 2‑chlorophenyl species (claim 4). Relevance is as §103 background art on the process steps, not as §102 art.

3.2 U.S. Pat. No. 3,846,410 (issued Nov. 5, 1974)

• Full citation: U.S. Patent 3,846,410, issued Nov. 5, 1974. (Assignee/inventor not verified in this session.)
• Publication/filing date: issued Nov. 5, 1974.
• Ground of citation in '957: cited for ketal–ketone–alcohol interconversions at the 8‑position — verbatim: "the ketal group … may be converted to an 8‑position ketone by subjecting the ketal group to a mild acid hydrolysis. The 8‑ketone can then be converted to a 8‑position secondary or tertiary alcohol which is racemic in nature. The reaction conditions therefor, for the above two steps, are found in U.S. Pat. No. 3,846,410 issued Nov. 5, 1974."
• Brief description: Benzodiazepine process art covering hydrolysis of protected ketones (ketals) and elaboration of 8‑position alcohols.
• §102 potential: Does not anticipate claims 1–5. It addresses functional‑group transformations on the fused benzo ring, not the imidazo‑fusion or the specific R₁/R₆ combinations recited. Note the date: it issued after the listed 1974‑09‑11 priority date, so relative to claims entitled to that date it can only be §102(e) art (effective as of its own filing date, if earlier than the invention date) or §102(b) art measured against the 1978‑05‑15 filing; it is not §102(a)/(b) art as of issuance against a 1974 invention date.

3.3 U.S. Pat. No. 3,868,362 — Fryer et al. (issued Feb. 25, 1975)

• Full citation: U.S. Patent 3,868,362, inventor Rodney I. Fryer et al., issued Feb. 25, 1975.
• Ground of citation in '957: cited for ring‑forming reaction of formula IA compounds with ethylene/propylene oxide — verbatim: "Reaction parameters and conditions to effect such a reaction are known in the art, see for example U.S. Pat. No. 3,868,362 issued Feb. 25, 1975 to Fryer et al. and U.S. Pat. No. 3,905,956 issued Sept. 16, 1975 to Derieg et al."
• Brief description: Roche art on oxazolo‑type ring formation from benzodiazepine substrates with epoxides under Lewis‑acid catalysis.
• §102 potential: Does not anticipate claims 1–5. Same reasoning as 3.1/3.2 — different ring system/substituent set; the reference is directed to a ring‑closure variant (Formula IA oxazolo compounds), expressly an alternative to, not a disclosure of, the claimed imidazodiazepines. Again §103‑type background.

3.4 U.S. Pat. No. 3,905,956 — Derieg et al. (issued Sept. 16, 1975)

• Full citation: U.S. Patent 3,905,956, inventor M. E. Derieg et al., issued Sept. 16, 1975.
• Ground of citation in '957: cited jointly with U.S. 3,868,362 for the same epoxide/oxazolo reaction conditions (see quote in 3.3).
• Brief description: Benzodiazepine process art on oxazolo‑containing benzodiazepine derivatives and their formation.
• §102 potential: Does not anticipate claims 1–5. A post‑priority (Sept. 16, 1975) U.S. patent; like 3.2 and 3.3 it is at best §102(e) art and discloses a different (oxazolo) ring system. No disclosure of the imidazo[1,5‑a][1,4]benzodiazepine nucleus or of the midazolam species.

4. Patent reference confirmed on the face of a same‑family sibling (highly likely also on the '957 face)

4.1 U.S. Pat. No. 3,551,412 — Schmitt (issued December 1970)

• Full citation: U.S. Patent 3,551,412, inventor Schmitt, issued December 1970; classified at 260/239.3 D (the 1,4‑benzodiazepine class).
• Where confirmed: On the printed front page of U.S. 4,401,597 ("[56] References Cited — U.S. PATENT DOCUMENTS — 3,551,412 12/1970 Schmitt … 260/239.3 D"). U.S. 4,401,597 is a division of Ser. No. 905,820 — i.e., of the very application that issued as U.S. 4,280,957; its front page reads: "This is a division of application Ser. No. 905,820 filed May 15, 1978, now U.S. Pat. No. 4,280,957…" Source: https://patentimages.storage.googleapis.com/7f/17/e2/878a347cf00b28/[US4368157](/patent/US4368157).pdf
• Brief description: A U.S. benzodiazepine patent (Schmitt), Class 260/239.3 D. (I did not verify its title/subject matter in this session and will not guess it.)
• §102 potential: Very unlikely to anticipate any of claims 1–5. Its classification and December 1970 date place it squarely in the pre‑existing 1,4‑benzodiazepine art, which does not disclose an imidazo‑fused 1,4‑benzodiazepine. It is, however, the reference most likely to be cited against claim 1 under §103 (as the closest benzodiazepine nucleus art), and it is §102(b) art by date (Dec. 1970 > 1 year before either the 1974 priority or the 1978 filing).
• Confidence note: That the same-number reference appears on the '957 face is an inference from the sibling's front page, not a direct reading of the '957 face. Treat as probable, unverified.

5. Non‑patent literature cited in the '957 specification

Neither is anticipatory art for any claim; both are cited as enabling background for process steps the specification already assumes.

6. Overall §102 conclusion

No patent citation traceable to U.S. 4,280,957 anticipates claims 1–5 under 35 U.S.C. § 102. The reason is structural: every patent document cited in (or adjacent to) the '957 disclosure is drawn to the unfused 1,4‑benzodiazepine nucleus or to process conditions for leaving‑group displacement, ketal hydrolysis, and oxazolo ring closure. None discloses:

• the imidazo[1,5‑a][1,4]benzodiazepine fused nucleus required by claim 1; or the specific species of claims 2–5 (midazolam maleate; the 1,4‑dimethyl analogue maleate; the 2‑chlorophenyl analogue).

Their real force is § 103 obviousness (as the closest prior benzodiazepine art combined with routine process steps), not § 102 anticipation. The U.S. references cited are, by date, §102(b)/(e)-eligible art, so they are legally available — they simply do not teach the claimed subject matter.

Key dates to keep straight for the §102 analysis. The critical date is set by the priority chain. The '957 specification states: "This is a continuation, of application Ser. No. 663,660 filed Mar. 4, 1978 now abandoned which is a CIP of Ser. No. 602,691, filed Aug. 7, 1975 … which is a CIP of Ser. No. 504,924, filed Sept. 11, 1974…" If a claim is supported by the 1974 disclosure, its critical date is Sept. 11, 1974 (and §102(b) art must predate Sept. 11, 1973). This matters because U.S. 3,846,410 (Nov. 5, 1974), U.S. 3,868,362 (Feb. 25, 1975), and U.S. 3,905,956 (Sept. 16, 1975) each issued after the 1974 priority date and therefore cannot be §102(a) art as of issuance — only §102(e) (as of their own filing dates) or §102(b) measured against the 1978‑05‑15 filing.

7. Discrepancies / flags (do not silently harmonize)

1. Parent application filing date is inconsistent across the family. The '957 specification (as supplied) says Ser. No. 663,660 was "filed Mar. 4, 1978", but the sibling patents U.S. 4,368,157 and U.S. 4,401,597 both state "Ser. No. 663,660, Mar. 4, 1976." One of these is a typographical/transcription error. Given Google Patents lists the '957 priority date as 1974‑09‑11 and the filing as 1978‑05‑15, the 1976 date is the more coherent reading, but I am reporting both as found rather than correcting either.
2. "External priority" oddity. The Google Patents record shows "1977‑02‑08 Priority claimed from US05/766,637 external‑priority → patent/US4076939A." This does not match the CIP chain recited in the specification and should be verified against the actual priority document before it is relied on for any §102 date computation.
3. Unverified face citations. As stated in §2, I could not read the '[56]' list printed on the '957 face. The four U.S. patents in §3 are cited in the body of the '957 specification; U.S. 3,551,412 in §4 is confirmed on a same‑family sibling's face. I did not verify whether the '957 face lists additional references (e.g., further Sternbach/Fryer benzodiazepine patents).

Suggested verification steps

• Pull the '957 issued front page (PDF) to read the '[56] References Cited' block directly: https://patents.google.com/patent/US4280957/en (download PDF).
• Cross-check each listed number in USPTO Patent Public Search (ppubs.uspto.gov) and Espacenet for exact filing/issue dates.
• For the same-family divisionals (U.S. 4,340‑series, 4,368,157–4,368,159, 4,401,597, 4,377,523), note that these are not prior art against the '957 patent — they share the Ser. No. 905,820 priority and would be §102(b)(2)/same-family references only, not anticipatory.

If you can supply the '957 front‑page PDF or an Espacenet "Cited documents" export, I can convert this into a per‑reference anticipation chart keyed to each claim element.

I'll gather the prior-art references cited on the patent's face and in its specification, then analyze the § 103 case.

Obviousness Analysis Under 35 U.S.C. § 103 — U.S. Patent No. 4,280,957

Scope note (building on the earlier litigation section). The litigation section concluded there is no located litigation asserting this patent. Nothing in the material I retrieved for this section changes that. What follows is a technical § 103 analysis only — not a validity opinion, and not a substitute for a claim chart built on the issued claim set.

1. What I treated as the "Prior Art section," and what the record actually contains

Verification status — read this first. I could not retrieve a clean, standalone examiner "References Cited" block for US 4,280,957. The Google Patents page as fetched exposes (a) a "Prior art keywords" field — benzodiazepine, chloro, methyl, imidazo, formula — and (b) the reference set cited inside the specification itself (column text), rather than a formatted front-page citation list. Additional art surfaced through the searches I ran (Roche/Sternbach benzodiazepine filings, the Walser et al. 1978 J. Org. Chem. paper). I flag provenance for each item below so nothing is presented as an examiner citation when it is not.

Source anchor: https://patents.google.com/patent/US4280957/en

Contradiction flagged (do not smooth over). The specification of US 4,280,957 states the immediate parent is "application Ser. No. 663,660 filed Mar. 4, 1978, now abandoned." The sibling patent US 4,368,157 (same family, division of Ser. No. 905,820) is reprinted with "Ser. No. 663,660, Mar. 4, 1976, abandoned." A Mar. 4, 1978 filing cannot be the parent of a CIP filed Aug. 7, 1975 (Ser. No. 602,691), so the 1978 date in the 4,280,957 text is internally inconsistent with its own priority chain. This matters directly for § 103 — see § 3.

Separately, the Google Patents family block shows "Priority date 1974‑09‑11" while the same page shows "1977‑02‑08 Priority claimed from US05/766,637."

2. Claim scope to be tested

From the patent text and page metadata, the claims fall into these buckets:

1. Compound claims — broad genus (Formula I / IC): imidazo-fused 1,4-benzodiazepines with A being the fused-ring variants, R¹–R⁶ as defined, R₅ = alkanoyloxy/hydroxy/hydrogen, plus pharmaceutically acceptable salts.
2. Preferred sub-genus claims (Formula IC/ID): 8-position R⁴ = H/nitro/halogen (preferably Cl); R⁶ = phenyl or 2-substituted phenyl (preferably 2-halo, "with fluorine being the preferred halogen"); R² = H or lower alkyl; R³ = H or lower alkyl (ID = 1‑methyl, optically active).
3. Species/salt claims: page metadata ties the maleate of 8‑chloro‑6‑(2‑fluorophenyl)‑1,4‑dimethyl‑4H‑imidazo[1,5‑a][1,4]benzodiazepine to a claim group ("claims 11"), and the specification identifies the two most preferred salts as the maleates of 8‑chloro‑6‑(2‑fluorophenyl)‑1‑methyl‑ (and 1,4‑dimethyl‑) 4H‑imidazo[1,5‑a][1,4]benzodiazepine.
4. Process claims ("and processes therefor" per the title): nitrosation of a 2‑(alkylamino)benzodiazepine → condensation with a nitroalkane anion → reduction (Raney Ni / LiAlH₄) → acylation → cyclization (PPA/P₂O₅/concentrated H₂SO₄, or direct orthoester/orthoamide/ester-imidate route) → dehydrogenation (MnO₂, Pd/C).
5. Intermediates are carved out into divisionals (US 4,347,364; 4,368,157–4,368,159; etc., from the family block) rather than being the substance of this patent.

3. Threshold issue: which references are even available (§ 102/§ 103 date gate)

The obviousness case changes materially depending on the claims' effective filing date:

• If claims get 1974‑09‑11, then US 3,846,410, 3,868,362 and 3,905,956 are unusable as prior art (all issued after that date), and the Walser J. Org. Chem. paper (1978) is unusable as a § 102/103 reference.
• If claims depend on subject matter first added in the 1975/1976 CIP (the specification openly adds material: the thieno examples, the oxazolo/V-substituted analogs, and the entire later reaction-scheme chapter XIII→LV), those claims get the later date and the 1974–1976 references become available.
• Under the "by others" rules, note that US 3,681,341 is Fryer's own earlier patent, but a § 102(b) statutory bar is not avoided by common inventorship (In re Katz / In re Land line), so it remains art against the broad claims. Archer & Sternbach are others in any event.

This is the single biggest lever for a challenger: the broader the genus actually claimed, the more likely it straddles the CIP and exposes the 1974–1976 art.

4. Proposed § 103 combinations

Combination A — broad genus compound claims (Formula I/IC)

A1 (Archer & Sternbach 1964) + (US 3,681,341) + the known 2‑amino/2‑(methylamino)‑5‑aryl‑1,4‑benzodiazepine scaffold.

• Archer & Sternbach and US 3,681,341 establish that the 2‑position of the 1,4‑benzodiazepine is a functionalizable/leaving-group position (alkoxy, alkylthio, and — per the specification's own citation of Archer & Sternbach — nitrosoalkylamino). The specification itself concedes these are "well known in the art."
• The S. African 68 01,075 / NO 119798 art establishes the 2‑amino‑5‑phenyl‑3H‑1,4‑benzodiazepine genus as known CNS-active sedatives/anticonvulsants — i.e., the scaffold and the desired activity were known.
• Motivation: to annulate the 1,2‑positions into a fused five-membered N-heterocycle to alter metabolic stability/potency while retaining the recognized 7‑halo‑5‑aryl‑1,4‑benzodiazepine pharmacophore. The patent's own examples start from exactly these known 2‑amino intermediates.
• Result: the Formula I/IC genus, prima facie.

A2 — the cyclization step, on the specification's own admissions. The specification lists orthoesters, orthoamides (DMF dimethylacetal, hexamethylmethanetriamine), nitriles ("e.g., acetonitrile"), and ester imidates as equivalents, and states the direct reaction "occurs spontaneously." Where a patent's own specification characterizes a set of reagents as equivalent cyclizing agents, that is powerful evidence of predictable, expected results — i.e., routine optimization over a finite, identified set (KSR factors; under the older Graham/In re Dillon framework, "obvious to try" with predictable results). A challenger would argue the genus claims cover nothing more than the union of these admitted equivalents.

Combination B — preferred sub-genus (8‑Cl, 2′‑halophenyl, 1‑methyl)

B1: Combination A + the then-conventional 7/8‑halo and 5‑(2‑halophenyl) substitution on 1,4‑benzodiazepines.

• The 7‑chloro/5‑phenyl core (chlordiazepoxide/diazepam lineage, in the Roche/Sternbach art above) and 5‑(2‑halophenyl) analogs supply the "8‑Cl" and "2′‑halophenyl" elements.
• Gap I must flag explicitly: I could not verify from the retrieved prior-art material a pre‑1974 reference that expressly teaches 2′‑fluoro (as opposed to 2′‑chloro) on the 5‑phenyl of a 1,4‑benzodiazepine. The "fluorine being the preferred halogen" preference is the patent's own assertion. A challenger asserting obviousness of the 2′‑fluoro species would need a reference or a well-founded bioisostere/routine-substitution rationale (halogen interchange on an established scaffold) — that argument is available but is not yet grounded in a located reference here. Flagging rather than asserting.

Combination C — process claims (the strongest § 103 case)

C1: (Archer & Sternbach 1964) + (US 3,681,341) + the standard Henry/nitroalkane condensation + Raney‑Ni reduction + acylation + acid-mediated cyclization + MnO₂ dehydrogenation.

Each step is a textbook transformation:

• Nitrosation with NaNO₂/acid, alkyl nitrite, or NOCl/pyridine — taught ad hoc by Archer & Sternbach.
• Nitroalkane anion condensation (nitromethane/nitroethane + KOtBu, NaH, LiNH₂) — standard, and the specification lists the bases and solvents as interchangeable.
• Raney‑Ni hydrogenation of a nitro/nitromethylene group to an aminomethyl group — routine.
• Acylation (acetic/propionic anhydride) and acid-catalyzed cyclization (PPA, P₂O₅, H₂SO₄, 100–200 °C) — the specification's own ranges overlap the conventional window.
• Dehydrogenation (MnO₂ or Pd/C; KMnO₄ noted) — the specification describes it as a simple oxidation/dehydrogenation at 25–200 °C.
• Motivation: there is no disclosed alternative route from a 2‑(methylamino)benzodiazepine to the fused imidazole; the specification notes the sequence "may proceed … to compounds of formula IF without the requirement of isolating any formed intermediate compounds," i.e., it is a conventional telescoped synthesis.

Under KSR, the process claims are the most vulnerable: every step is a known technique applied to a known class of substrate with predictable outcome, and the patent itself presents the variables (leaving groups, bases, solvents, temperatures) as routine choices.

Combination D — thieno/other fused analogs

The genus also covers thieno-fused species (e.g., 8‑chlorothieno[3,2‑f]; the examples use 2‑methylamino‑5‑phenyl‑3H‑thieno[3,2‑e][1,4]diazepine and 7‑chloro‑5‑phenyl‑2‑methylamino‑3H‑thieno[2,3‑e][1,4]diazepine). Given that thieno-1,4-diazepines were known CNS-active benzodiazepine bioisosteres, applying the identical nitrosation/nitroalkane/cyclization sequence to the thieno starting material is a substitution of a known ring homolog with predictable results (In re Papesch-type reasoning). This is the cleanest obviousness attack on the scope of the genus (as opposed to the preferred species).

Combination E — 3-position variable groups, salts, and optical isomers

• The specification's chapter XV→XLIV is a systematic catalogue of routine transformations on a 3‑ester/3‑hydroxymethyl/3‑aldehyde handle: hydrolysis, amidation, hydrazinolysis, chlorination (PCl₅), amine displacement, oxidation (MnO₂, CrO₃), oxime/oxime-ether formation, Grignard addition, Curtius rearrangement. Claims reciting carboxamide, dimethylcarboxamido, carboxylic acid hydrazide, acetyl, hydroxymethyl, oxime are squarely routine derivatives of a disclosed ester/aldehyde — obvious under In re Papesch.
• Pharmaceutically acceptable salts (HCl, maleate, tartrate, etc.) and optical resolution (the specification cites Fieser & Fieser, Advanced Organic Chemistry (1961), pp. 85–88, for resolving ID) are per se conventional.

5. Motivation to combine — the affirmative case a challenger would make

1. Same field, same problem, same pharmacophore. All references are 1,4-benzodiazepine/CNS chemistry; the combination keeps the recognized 7‑halo‑5‑aryl‑1,4‑benzodiazepine activity core.
2. Known, finite, enumerated options. The specification itself calls the leaving groups and cyclizing agents "well known in the art" and "equivalents." Predictable results over identified options is the classic KSR rationale.
3. Reasonable expectation of success. The patent reports no failure of any listed cyclizing agent or leaving group; the direct orthoester route "occurs spontaneously."
4. "Obvious to try" / structural homology. Fusing a fifth ring onto a known benzodiazepine (as with other fused benzodiazepine series of that era — a background point that would need its own citations) was an established strategy for modulating benzodiazepine activity; a Papesch-style argument treats a new homolog as obvious absent unexpected properties.

6. Where the prima facie case is weak or unsupported (counter-arguments to preserve)

• No located reference discloses the imidazo[1,5-a][1,4]benzodiazepine ring system itself, pre‑1974. The strongest art in the record (Archer & Sternbach; US 3,681,341) is about 2-position functionalization of benzodiazepines, not about the fused imidazole. A challenger must bridge from "functionalize C‑2" to "cyclize onto N‑1 with a one-carbon unit" without a located teaching.
• The 1974–1976 references cut both ways. US 3,846,410, 3,868,362, 3,905,956 and the 1978 Walser paper are only available if the claims lose the 1974 priority date. Conversely, if the claims are fully supported by the 1974 disclosure, the strongest "imidazodiazepine" teaching — Walser et al. 1978 — is the inventors' own later publication and unavailable.
• 2′‑fluoro is unverified from located art (see Gap in Combination B). This is the specific feature of the commercial species (midazolam) and the most likely non-obviousness anchor for the preferred claims.
• Unexpected properties asserted but not proven. The specification states that the compounds are "particularly useful when utilized in intravenous and intramuscular preparations because of the acid addition salts' solubility in aqueous solution." That is an assertion of an advantage; the record I retrieved contains no comparative solubility/activity data (no head-to-head versus prior benzodiazepines). Without data, the argument is weak — but if in vivo solubility/short-duration data exist in the file wrapper, they are the natural non-obviousness hook.
• Secondary considerations are not in this record. Midazolam (Versed) commercial success is real and large, but § 103 requires nexus to the claimed invention over the prior art, and the patent text itself supplies no commercial-success or long-felt-need evidence. Preserve as a potential rebuttal, not as evidence in hand.
• Genus breadth is a double-edged vulnerability. A genus this broad (Formulas I/IA/IE, thieno and thiadiazole-fused variants per the C07D classes) is easier to invalidate on the broad claims, and the species-specific claims are easier to defend — exactly the usual outcome asymmetry.

7. Bottom line

• Strongest § 103 challenge: the process claims. Combination C — (Archer & Sternbach 1964) + (US 3,681,341) + routine nitrosation/nitroalkane-condensation/reduction/acylation/cyclization/dehydrogenation — has the best motivation, the best predictability, and the patent's own specification supplies the equivalency admissions.
• Moderate challenge: the broad genus compound claims, via Combination A/D (known scaffold + known cyclization strategies + known thieno homolog), with the date gate in § 3 as the swing factor.
• Weakest challenge: the preferred sub-genus and species claims (8‑Cl, 1‑methyl, 2′‑fluorophenyl, and the 3‑carboxamide/hydrazide/maleate claims), pending (i) a pre‑1974 teaching of 2′‑halo/fluoro‑5‑phenyl benzodiazepines and (ii) any unexpected-property data from the file wrapper.
• Open contradictions carried forward: (a) the parent application date for Ser. No. 663,660 is stated as Mar. 4, 1978 in US 4,280,957 but as Mar. 4, 1976 in the sibling US 4,368,157 record — unresolved and material to the § 103 date gate; (b) the family block shows a 1977‑02‑08 priority claim to Ser. No. 766,637 (US 4,076,939) that is not described in the 4,280,957 specification's own priority paragraph.

What I could not verify: the examiner's actual "References Cited" list; any pre‑1974 teaching of 2′‑fluoro substitution; and the contents of Walser, Zenchoff & Fryer, J. Med. Chem. 19, 1378 (1976) (surfaced only as a bibliography entry, likely material as 102(a)/103 art if the claims lose the 1974 date). If you can supply the file wrapper and the front-page citation list, I can convert this into a claim-by-claim chart.