US 4973679

I'll search for this specific patent number and related litigation/docket information.

Let me search for the claims text and any litigation/docket references.

US 4,973,679 — Verified Patent Record

Caveat on sources: Everything below is grounded in the authoritative full text of US4973679A supplied in the prompt (Google Patents, fetched 2026-09-30) plus live search results. Two important limitations: (a) the supplied Google Patents text does not include the claims section, so I cannot quote claim language verbatim — I flag this explicitly below; (b) I found no CAFC 2026 docket, PTAB proceeding, or district-court case naming this patent. I have not fabricated any.

Bibliographic data (as recorded)

Continuity chain (from the specification): This is a divisional of Ser. No. 637,927, filed Aug. 6, 1984, now US 4,668,777; that application was a continuation of Ser. No. 358,589, filed Mar. 16, 1982, now abandoned; which was a continuation-in-part of Ser. No. 248,450, filed Mar. 27, 1981, now US 4,415,732. (One third-party aggregator page lists a priority date of 1981-03-26; the authoritative record says 1981-03-27.)

Abstract (verbatim)

"A new class of nucleoside phosphoramidites which are relatively stable to permit isolation thereof and storage at room temperature. The phosphoramidites are derivatives of saturated secondary amines."

Plain-language overview of the disclosure

The patent covers the phosphoramidite approach to solid-phase oligonucleotide synthesis — the chemistry that became the industry-standard DNA synthesis method. The core inventive point is a stability/reactivity trade-off:

• Older phosphoramidites bearing unsaturated nitrogen heterocycles (tetrazole, imidazole, benzimidazole, indole, etc.) are extremely reactive but correspondingly unstable — they hydrolyze with water and oxidize in air, requiring inert atmosphere and storage well below 0 °C.
• The patent claims phosphoramidites derived from saturated secondary amines (dimethylamino, diethylamino, diisopropylamino, pyrrolidino, morpholino, piperidino, etc.). These are less reactive but stable enough to be isolated as dry powders, stored at room temperature under nitrogen, and still react readily with an unblocked 3′- or 5′-OH of a nucleoside during chain assembly.
• Supporting subject matter includes: preparation of the chloro-(secondary amino)alkoxyphosphine reagent; activation of the amidite by mild protic acids (tetrazole, amine hydrochlorides); oxidation of the phosphite triester to phosphate (iodine, peroxides, N-chlorosuccinimide); and use of triarylmethyl ("trityl"-type) blocking groups that are color-coded — each triarylmethyl group gives a characteristic color on acid (e.g., ZnBr₂) cleavage, enabling step-by-step spectrophotometric monitoring of coupling yield and sequence. Table I lists dozens of triarylmethyl variants with their observed colors.

Definitions used in the formulas (from the specification): ⌀P = inorganic polymer (e.g., silica gel) linked via a base-hydrolyzable covalent bond; R = H or a blocking group; R¹′ = hydrocarbyl up to 10 carbons; B = nucleoside/deoxynucleoside base; A = H, OH or OR⁴; and X = halogen (Cl, Br) or NR²′R³′, the saturated secondary amino group that is the claimed point of novelty.

Independent claims — what I can and cannot say

I do not have the verbatim claim text, and I will not reconstruct it. The supplied authoritative document includes the abstract, description, and examples but the claims set itself was not captured. Based on the specification and the Google Patents "prior art keywords" extract derived from claim vocabulary — "sub," "process according," "nucleoside," "group," "anisylphenylmethyl" — the independent claims appear to be directed to two statutory classes:

1. A composition-of-matter claim to a phosphoramidite compound of structure II/IIa (nucleoside 3′- or 5′-phosphoramidite bearing an alkoxy group R¹′ and a saturated secondary amino substituent X = NR²′R³′, as defined above, including the ring-forming definitions covering saturated N-, O-, and S-heterocycles).
2. A process claim ("process according to…") for forming an internucleotide linkage by activating such a phosphoramidite with a proton donor and condensing it with a blocked nucleoside/oligonucleotide, oxidizing the resulting phosphite to phosphate, and repeating to build a defined-sequence oligonucleotide.

The recurrence of "anisylphenylmethyl" in the claim vocabulary strongly indicates the claims recite the dimethoxytrityl (di-p-anisylphenylmethyl, DMT) 5′-blocking group expressly.

If you need exact claim language, obtain it from the USPTO PatentCenter/PatFT full-text for US 4,973,679 (or the patent PDF). I can summarize the claims precisely once the claim sheet is supplied.

Litigation / CAFC 2026 check

• No CAFC 2026 docket, appeal, or district-court action for US 4,973,679 was found. The patent has been expired since 2007-11-27, which makes current infringement litigation essentially implausible.
• The Google Patents record does carry a "Family has litigation" flag ("First worldwide family litigation filed," sourced to Darts-IP for family 27400129), meaning some member of this patent family has been litigated at some point historically — it does not identify a 2026 CAFC proceeding, and I could not verify any specific case from that flag. Treat it as a family-level indicator only.
• This patent is heavily cited as prior art and as the foundational reference for the standard phosphoramidite DNA-synthesis method (it appears in the "patent documents cited" lists of numerous later patents, including US 5,132,418 and many modern oligonucleotide filings).

Confidence statement

High confidence on: patent number, title text, inventors, assignee, application number, filing date (1986-09-18), issue date (1990-11-27), priority date (1981-03-27), expired status, abstract, and the continuity chain. Low/uncertain on: the exact wording and count of the claims (not present in the supplied text) and any specific litigation history beyond the family-level flag.

I'll research litigation involving US patent 4973679. Let me run several targeted searches.

Let me dig deeper with more specific searches.

I found a relevant lead involving University Patents, Inc. Let me investigate further.

Summary of findings

I could not identify any litigation in which U.S. Patent No. 4,973,679 ("the '679 patent") was itself asserted as a patent‑in‑suit with a citable case name, docket number, or outcome. Nothing in the searches returned a complaint, judgment, or docket naming the '679 patent specifically. What I can document is (a) a family-level litigation flag on the patent record itself, and (b) a closely related, real case involving the same patent owner and the same Caruthers/Beaucage phosphoramidite patent family. Details and caveats follow.

1. The '679 patent's own record carries a litigation flag

The Google Patents record for US4973679A states:

"Family has litigation — First worldwide family litigation filed"
https://patents.darts-ip.com/?family=27400129&...&patent=[US4973679](/patent/US4973679)(A)

This is a Darts‑IP family flag. It indicates that at least one member of the worldwide family (priority chain rooted in US 4,415,732, through 4,668,777, with 4,973,679 as a divisional of 4,668,777) has been involved in litigation somewhere. It does not establish that the '679 patent specifically was asserted, nor does it give a case name, court, or docket number. Google Patents itself disclaims any legal conclusion on status.

Treat this as a lead requiring paid‑database verification, not as a case citation.

2. Documented related litigation (same patent owner, same family)

Outcome/status: The reported decision resolved UPI's motion to dismiss (denied) and motion to transfer (denied). I have no verified information on the ultimate outcome of the case, the patents finally adjudicated, or any appeal. Do not represent this as a '679 case without checking the full docket.

3. Evidence the '679 patent sits inside a defined patent portfolio

Justia's contracts dictionary contains a defined term:

"PEB DNA Synthesis and Purification Patents. U.S. Patent Nos. 4,997,927 (GBF), 4,458,066, 5,132,418, 5,153,319, 4,973,679 (Caruthers Process), and 4,415,732, 4,668,777, 4,500,707 (Caruthers Reagents), including any Related Patent."
https://dictionary.contracts.justia.com/peb-dna-synthesis-and-purification-patents/

This shows the '679 patent was expressly named (as "Caruthers Process") in an agreement defining a DNA‑synthesis patent portfolio — consistent with licensing/settlement activity in this technology space, but it is a contract definition, not a litigation record.

4. False positives to exclude (different patents — do not conflate)

Several search hits involve patents with similar but different numbers:

• Warsaw Orthopedic, Inc. v. NuVasive, Inc., No. 3:08‑cv‑01512 (S.D. Cal.), $101.2M verdict (Sept. 20, 2011), appeal Nos. 2013‑1576,‑1577 (Fed. Cir.) — this concerns the ''973 patent' = U.S. 5,860,973, a spinal‑implant patent. Not 4,973,679.
• Warsaw v. NuVasive also involved '933 (6,945,933), '586, '236, '661, '051, '050, '320, '390, '542.
• D. Del. opinion No. 19‑1410 — patents '681, '703, '176, '097. Unrelated.
• EP 0022645 / IT 4973679 — an Italian priority number for a heat‑storage patent. Unrelated to the US patent.

5. What I could not obtain (and why)

My tool access was limited to web search and was capped before I could query the litigation databases directly. I did not successfully search:

• Unified Patents litigation portal (portal.unifiedpatents.com/litigation/caselist)
• PACER / CourtListener docket search for the patent number
• Darts‑IP family 27400129
• RPX Insight / midpage litigation records

I therefore cannot state with high confidence that no litigation exists. The correct statement is: no litigation specifically asserting US 4,973,679 was identified in the sources I could reach.

6. Recommended verification steps

To definitively answer this, check (in order):

1. Darts‑IP family 27400129 (linked from the patent's Google Patents page) — the flagging source.
2. Unified Patents litigation portal — search "4973679".
3. RPX Insight (insight.rpxcorp.com) — free litigation search by patent number.
4. PACER / CourtListener RECAP — full‑text docket search for "4,973,679".
5. LexisNexis/Westlaw — Millipore Corp. v. University Patents, Inc. full docket (D. Del.), to see whether 4,973,679 was ever added after its 1990 issuance.
6. Justia/JPTOS assignment records for University Patents Inc. — to trace the litigation‑related licensees.

Bottom line

• No specific case asserting US 4,973,679 was found. I am not aware, from the information available, of any reported decision naming it as a patent‑in‑suit.
• The patent's official record carries a "Family has litigation" flag (Darts‑IP family 27400129), indicating some family member was litigated — the specific case and patent are not identified by that flag.
• The best‑documented related case is Millipore Corp. v. University Patents, Inc., 682 F. Supp. 227 (1988), a DJ action against the same owner over the earlier Caruthers phosphoramidite patents; the '679 patent issued two years after that decision.
• The '679 patent does appear as "Caruthers Process" in a defined patent portfolio ("PEB DNA Synthesis and Purification Patents") in a Justia contract record — evidence of licensing activity, not of litigation.

Caveat: I have not verified any of the above against a primary litigation database, and patent‑number identifiers have been interpreted literally as instructed (e.g., '973 ≠ 4,973,679).

I'll start by verifying the structured data with targeted searches for any PTAB or litigation activity on this patent.

Let me check for PTAB activity, reexaminations, and the litigation history more specifically.

No PTAB hits so far. Let me check the enforcement/reexamination history and confirm whether AIA trials were even possible.

PTAB / AIA-Trial Analysis — U.S. Patent No. 4,973,679

Data sources: structured "PTAB proceedings on file" block (USPTO ODP, no AIA trials indexed) + open-web verification (PTAB E2E captures, docket aggregators, Google Patents family data, CourtListener). Verification date: 2026-09-30.

Proceedings overview

Total AIA trial proceedings on file: 0 — 0 active, 0 with claims canceled, 0 with claims sustained, 0 settled, 0 institution denials. The structured ODP block is confirmed by open-web checking: no IPR, PGR, or CBM docket references to U.S. 4,973,679 surfaced anywhere, and Google Patents' family record flags litigation only (Darts-IP family 27400129), not PTAB trials.

The defensive posture is unusual, and it is not "hardened vs. untested" — it is moot. U.S. 4,973,679 issued 1990-11-27 and reached its anticipated expiration on 2007-11-27 ("Expired – Lifetime" in ODP). The patent's entire enforceable life preceded the AIA: IPR practice did not even begin until 2012-09-16. Any assertion today is a document-collection exercise, not a litigation threat — see "Recommended next steps."

Proceedings

None to enumerate. No IPR, PGR, or CBM proceeding has ever been filed against U.S. 4,973,679, and none was legally available in the window that mattered:

For completeness on the prior-art background that would have been the basis of any challenge: the patent's own specification and prosecution history are built on the Caruthers/Beaucage phosphoramidite work (Beaucage & Caruthers, Tetrahedron Lett. 1981, 22, 1859–1862), and the family was litigated in district court in the late 1980s/1990s rather than at the Board.

Non-AIA activity worth flagging (not PTAB proceedings):

• Millipore Corp. v. University Patents, Inc., 682 F. Supp. 227 (D. Mass. 1987) — declaratory-judgment action arising from UPI's threatened enforcement of the Caruthers patents through Applied Biosystems (ABI) sublicensing offers; UPI's motion to dismiss denied on reasonable apprehension of suit. Full text
• A later opinion addressing the '679 patent directly — it treats '679 as the sole patent of the "C & B line," and discusses UPI's non-disclosure of the Feb. 19, 1980 Caruthers/Matteucci Tetrahedron Letters article to the USPTO and EPO, with Applera/Applied Biosystems as defendant. Retrieved from CourtListener, but I could not confirm the caption or exact filing year from the excerpt I retrieved — treat the date and caption as unverified and pull the docket before relying on it: storage.courtlistener.com/harvard_pdf/2526031.pdf
• ABI–Cruachem sublicense (1991-10-01) referencing a consent judgment/settlement agreement over the licensed patents, materially showing the family was resolved commercially rather than through AIA-style validity trials. Agreement

I found no reissue and no ex parte reexamination record for 4,973,679 in the sources searched, but I did not exhaustively query the USPTO reexamination database — flag that as an open item if you need certainty.

Strategic summary

Claim status: every claim of 4,973,679 is UNTESTED at any validity tribunal. No claim has been canceled, disclaimed, or confirmed by a PTAB final written decision, and there is no FWD to link to. I have not stated which claims are canceled or sustained because none are — and I am deliberately not enumerating claim numbers, because the claim text of '679 was not part of the record supplied to me and I will not guess at independent/dependent structure. Practically, the point is academic: the patent's 17-year term from the 1990-11-27 grant ran out on 2007-11-27, so the entire claim set is expired.

Estoppel landscape: § 315(e)(2) estoppel is inapplicable. IPR estoppel attaches only to petitioners who were party to an IPR that reached a final written decision under § 318(a). No IPR exists → no petitioner is estopped from anything, and no individual or entity has been barred. Conversely, the patent owner gained nothing either: there is no PTAB-tested, court-validated core to shelter behind. All prior art — including the 1980 Tetrahedron Letters article, the Letsinger/Lunsford phosphorochloridite work, the Köster silica-gel/triaryl linkage work, and the intervening Sinha/Köster phosphoramidite art — remains fully available in any forum. (If you are looking at the later Caruthers-line patents that manufactured oligos through the 1990s–2000s, e.g. U.S. 5,043,524 / 5,132,418 / 5,153,319 / 5,262,530, those are separate patents with separate expiration dates and must be cleared individually — don't infer anything about them from this analysis.)

Pattern signals: none of the usual ones. No serial petitioner, no defensive aggregator (Unified Patents, RPX, etc.) anywhere in the chain, no PTAB-to-Federal-Circuit appeal trail from this patent, and no sovereign-immunity or joinder activity. Patent Owner (University Patents, Inc.; original assignee of record) enforced the portfolio by licensing through ABI and litigating in district court in the late 1980s, and the last visible enforcement/settlement artifact is the 1991 ABI–Cruachem sublicense. The absence of IPRs is not the "well-asserted patents eventually attract IPRs" signal — it's a chronological impossibility, because AIA trials postdate the patent's death by five years.

Recommended next steps

1. If you are a defendant facing a demand letter citing U.S. 4,973,679: the patent is expired and unenforceable as of 2007-11-27. There is no live AIA proceeding to track, no FWD to cite, and no possibility of an injunction. The only theoretically available remedy would be pre-expiration damages, and the six-year limitations period of 35 U.S.C. § 286 (plus laches) closed years ago — the practical cutoff passed in 2013. Respond on that basis rather than building an IPR strategy around a dead patent. (There is, accordingly, no FWD for me to link and quote — the disposition is the expiration shown on the Google Patents record, not a Board ruling.)
2. If a counterparty is asserting the family, identify the actual asserted patent number first. The Caruthers/UPI family includes U.S. 4,415,732 (issued 1983-11-15), 4,668,777 (issued 1987-05-26), 5,043,524, 5,132,418, 5,153,319, and 5,262,530. Several of those have different expiration dates. Confirm the asserted patent and its expiration before doing anything else; a demand letter that recites '679 while the real claim is to a later patent is a red flag worth calling out.
3. If you nonetheless need a board-side kill for a different, unexpired family member: the prior-art backbone is well documented (Beaucage & Caruthers 1981; Letsinger & Lunsford, JACS 98:12, 3655–3661; Köster, Tetrahedron Lett. 1972, 1527–1530), and the same panel-relevant record is available. But note § 315(b)'s one-year bar runs from service of a complaint alleging infringement — calendar it from the complaint date, and remember Fintiv-era discretionary-denial practice is applied in a shifting Director-level framework; check the current guidance before filing.
4. Verify the two open items before you rely on this memo in a brief: (a) whether any ex parte reexamination was ever filed against 4,973,679, and (b) the caption/date of the CourtListener opinion at 2526031.pdf, which I could not fully identify from the retrieved excerpt.

Flag on the canonical source: I searched specifically for proceedings the ODP ingest might have missed (PTAB E2E docket captures, aggregator pages, litigation-family records) and surfaced none. The "no PTAB activity on file" default therefore holds on the facts, not just on the ingest gap.

I'll research the assignment chain for US 4,973,679 before writing anything up.

The initial searches didn't surface assignment records. Let me dig into the specific ownership history and legal events.

Let me look for the specific assignment records and the ownership status of University Patents, Inc.

Ownership & Assignment Analysis — US 4,973,679

Patent? "Process for oligonucleotide synthesis using phosphoramidite intermediates" — Caruthers & Beaucage, filed 1986‑09‑18 (Appl. 06/909,070), issued 1990‑11‑27, anticipated expiration 2007‑11‑27 ("Expired – Lifetime" per Google Patents). This is the Beaucage/Caruthers foundational phosphoramidite chemistry patent — the method underlying essentially all automated DNA/RNA synthesis.

Verification caveat up front. I was not able to retrieve any Assignment Center record (reel/frame, correspondent, conveyance type) for this patent during this session. Every reel/frame number, correspondent name, and execution date that would normally go in the "Assignment timeline" below is therefore absent rather than inferred. I have not filled gaps with plausible-looking numbers. What follows separates (a) hard documentary facts, (b) records I could not confirm, and (c) the specific search strings needed to close the gap.

Inventors

Unusual patterns worth flagging:

1. Inventor is also a principal of the exclusive licensee. Caruthers invented the chemistry, assigned it to University Patents, Inc., and co‑founded the company (ABI) that took the exclusive license and later sublicensed it. This is an inventor‑to‑licensee self‑dealing structure, not an arm's‑length inventor grant — the practical opposite of the "inventors silently depart before a fire‑sale" pattern.
2. No inventor departure signal. Caruthers remained a CU Boulder faculty member for decades and continued filing in the same family (US 5,132,418; 5,153,319; 5,262,530; 5,278,302; 5,602,244, etc.), all still credited to University Patents, Inc. There is no 12‑month post‑filing exodus.
3. Federal funding string. The specification states the inventions "were made in the course of work under a grant or award from the Department of Health, Education and Welfare." A Bayh‑Dole government license therefore encumbers the chain — relevant to chain‑of‑title completeness but not an assignment record per se.

Original assignee

University Patents, Inc. (UPI) — Norwalk, Connecticut. Google Patents lists UPI as both Original Assignee and Current Assignee, with no reassignment events shown.

• Line of business: a university technology‑transfer and patent‑licensing company — i.e., a patent‑holding, non‑manufacturing entity by design, not an operating company. Its portfolio spans multiple universities (this CU/Boulder DNA‑synthesis family; later Thomas R. Cech ribozyme and Caruthers phosphorodithioate patents issued 1993–1997 are still assigned to "University Patents, Inc." per Justia's assignee profile). UPI remained an active named assignee on new grants into at least 1997.
• Did it ship a product embodying the claims? No. UPI was a licensor. The practicing entity was Applied Biosystems, Inc. (ABIO/ABI), which held an exclusive license and granted sublicenses (e.g., the ABI → Cruachem Holdings Ltd. sublicense dated 1991‑10‑01, reproduced in a Transgenomic SEC exhibit, which recites "the name or other designation of UPI, The University of Colorado, or employees thereof"). Commercial DNA synthesizers and phosphoramidite reagents were sold by ABI and its sublicensees, not by UPI.
• Current status: not verified. UPI was clearly alive and enforcing/licensing through the early 1990s and still taking assignments of new patents through 1997. I could not confirm from a primary source whether UPI was later wound up, merged, or sold its portfolio. Treat "UPI still owns it" as the default reading of the Google Patents record, but as unconfirmed.
• Enforcement history (documented): UPI and ABIO ran a real mid‑1980s assertion campaign against DNA‑synthesizer competitors. The D. Del. declaratory‑judgment decision in Millipore Corp. v. University Patents, Inc. (CourtListener, opinion 1583542) recites UPI/ABIO "letters sent throughout the industry threatening suit to those who infringed UPI's patents," a pending California infringement action, an ABIO sublicense offer to Millipore with "the alternative … was litigation with UPI," and a January/February 1987 Millipore DJ complaint and amended complaint. Google Patents also carries a "Family has litigation" flag linking the Darts‑IP global litigation dataset for this family.

Assignment timeline

Finding: no post‑issuance assignment record was located, and the Assignment Center record could not be pulled during this session. Stated plainly, as required:

• Reel/frame, conveyance type, execution date, recording date, and correspondent of record: NOT RETRIEVED. I will not fabricate these.
• The publicly indexed evidence (Google Patents legal events / assignee fields) shows University Patents, Inc. as assignee at grant and as "current assignee," with no recorded reassignment, security interest, merger, or change‑of‑name event. Google Patents legal‑events data is known to lag actual USPTO Assignment Center records, so this is weak evidence of an unchanged chain, not proof of one.
• The only chain‑of‑title events I can document are provenance events, not USPTO reel/frame recordings:

To close the gap, in this order (each field above is retrievable):

1. https://assignmentcenter.uspto.gov/ → Patent Number search → 4973679; also search application 06/909,070 and the parent apps 06/637,927, 06/358,589, 06/248,450 (pre‑issuance inventor→UPI assignments are frequently recorded only against the application number).
2. Retrieve the Correspondent field on each record — that is the artifact you asked me to capture, and it is the one I could not obtain.
3. Cross‑check the same chains for the sibling patents US 4,415,732 / 4,458,066 / 4,500,707 / 4,668,777 / 5,132,418 / 5,153,319 / 5,262,530, which share a title chain; a single recorded transfer off UPI would almost certainly appear across the family, not on one patent.
4. USPTO ODP/PEDS for the application, plus the Transgenomic SEC exhibits for the ABI sublicense chain.

Timeline diagram

timeline
    title Ownership of US 4973679
    1981 : Invented at University of Colorado
         : Priority application filed
         : Assigned to University Patents Inc
    1983 : Parent patent US 4415732 issued
    1984 : Continuation application filed
    1986 : Divisional application filed
    1987 : Millipore files declaratory judgment suit
    1990 : US 4973679 issued to University Patents Inc
    1991 : ABI sublicense to Cruachem Holdings
    2007 : Patent expired

NPE / troll-pattern signals

Verdict

Insufficient data — with a documented non‑practicing‑owner overlay.

Justification: I could not pull a single Assignment Center record for US 4,973,679, so there is no reel/frame, no correspondent, and no conveyance type to support any NPE finding; the only ownership fact establishable from indexed sources is the original assignment to University Patents, Inc. (reflected in Google Patents' assignee fields at grant and as "current assignee," with no reassignment events), plus a federal‑funding string (DHHS), a 1981–1986 prosecution/priority chain, an ABI→Cruachem sublicense dated 1991‑10‑01, and 1987 declaratory‑judgment litigation (Millipore Corp. v. University Patents, Inc., https://www.courtlistener.com/opinion/1583542/millipore-corp-v-university-patents-inc/). Against your enumerated rubric, zero of the eight signals are present as strong signals: no shell‑entity transfer (UPI was non‑practicing from day one), no listed NPE assignee, no cascading LLC hops, no pre‑litigation transfer, no bankruptcy sale, no defensive aggregator. The one real "non‑practicing assertion" fact — UPI + exclusive licensee ABI enforcing against competitors with the inventor as ABI's co‑founder — is a mid‑1980s university tech‑transfer enforcement model, not a modern troll chain, and by itself does not clear the "NPE — moderate confidence" bar under your rules. Bottom line: this patent is expired (2007‑11‑27), the last verifiable owner is University Patents, Inc., and I could not confirm any transfer off UPI.

Verify here: https://assignmentcenter.uspto.gov/ (patent 4973679; also application 06/909,070) · https://assignment.uspto.gov/patent/index.html · https://patents.google.com/patent/US4973679/en

If you re‑run this with Assignment Center access, the three things to capture are: (1) every reel/frame for the family including the pre‑issuance inventor→UPI records; (2) the correspondent on each — a single recurring UPI/tech‑transfer‑shop attorney across the 1981–1997 filings would be the expected benign pattern, whereas a modern NPE firm name would be the actual finding; and (3) any record executed after 1997, which is the only window in which this chain could have become a troll asset — the patent had ~10 years of life left at that point.

I'll research US patent 4973679 and its cited prior art. Let me search.

Let me search specifically for the citation list of US 4973679.

Let me target the actual citation record for US 4973679 specifically.

US 4,973,679 — Prior-Art / Citation Analysis

1. Identification of the patent (literal numbers as given)

Source: https://patents.google.com/patent/US4973679/en

Continuity chain recited inside the patent's own description (authoritative):
US 4,973,679 is a divisional of Ser. No. 637,927 (filed 1984-08-06, now US 4,668,777), which is a continuation of Ser. No. 358,589 (filed 1982-03-16, now abandoned), which is a continuation-in-part of Ser. No. 248,450 (filed 1981-03-27, now US 4,415,732). The disclosure states the work was made under a Department of Health, Education and Welfare grant.

2. Important methodological caveat — please read before using this

You asked me to pull the citation record from the USPTO database and map each cited reference to specific claims under § 102. I must be explicit about a limitation rather than paper over it:

• I was not able to retrieve the enumerated examiner-citation table ("References Cited — U.S. Patent Documents / Foreign Patent Documents / Other Publications") for US 4,973,679 itself in this session. The citation tables that surfaced in search are from later patents that cite '679 (e.g. US 6,147,200, US 6,858,722, US 6,120,475, US 6,239,220, US 5,750,666, US 9,558,458, and various EP equivalents). Those lists record references cited by the later applicant, not by the '679 examiner. Cite them as such; do not represent them as the '679 prosecution record.
• The claim text of US 4,973,679 was not in the text supplied to me — only counts ("claims description 52 … 31") and fragments. An anticipation analysis under § 102 requires element-by-element comparison against actual claim language. Everything in § 5 below is therefore provisional and must be verified against the granted claims and the file wrapper (via USPTO PatentCenter / Global Dossier).
• Any statement I cannot ground in the supplied patent text or a retrieved URL is flagged as uncertain. I have not invented citation numbers.

3. Category A — Prior art acknowledged in the specification itself (verifiable from the patent text)

These three are the references the patent expressly identifies as prior art, all with effective dates well before the 1981-03-27 priority date, so all are potentially pre-AIA § 102(b) art.

A1. H. Köster, Tetrahedron Letters, 1972, pp. 1527–1530

• The patent states: "The attachment of nucleosidephosphates to silica gel using a trityl linking group is described in the prior art (H. Koster, Tetrahedron Letters, 1527-1530, 1972) but the method is apparently applicable only to pyrimidine nucleosides. The cleavage of the nucleoside from the silica support can only be accomplished with acid to which the purine nucleosides are sensitive."
• Potential § 102 exposure: limited to any claim drawn solely to (i) a silica-gel–bound nucleoside through a trityl-type linking group, or (ii) acid-mediated cleavage of such a bond. It does not disclose saturated-secondary-amino nucleoside phosphoramidites.

*A2. R. L. Letsinger & W. B. Lunsford, J. Am. Chem. Soc., 98(12), 3655–3661 (1976)*

• Patent's characterization: "production of phosphotriester derivatives of oligothymidylates … by reaction of a phosphorodichloridite with a 5'-O blocked thymidine and subsequent reaction of the product with a 3'-O blocked thymidine followed by oxidation … Unfortunately, the process requires separation and purification of products at each stage…"
• Potential § 102 exposure: any claim drawn to a method of forming an internucleotide phosphite/triester bond using a halophosphorodichloridite and oxidation. The patent distinguishes this art on the basis of the amino-substituted (amidite) reagents; the distinguishing feature is the reaction of the chloridite with a secondary amine, which Letsinger does not teach. Anticipation of the amidite claims is therefore unlikely; § 103 is the realistic risk.

A3. V. Amarnath & A. D. Broom, Chemical Reviews 77, 183–217 (1977)

• Patent's characterization: review of polymer supports for polynucleotide synthesis; problems of slow diffusion, excessive swelling, sorption of reagent.
• Potential § 102 exposure: none to the compound claims; it is background/§ 103 art on the "polymer-supported synthesis" limitation only.

4. Category B — Same-family / same-inventor documents (not third-party art)

These are the documents most likely to be cited against '679 during prosecution, but they are family members, so the correct analysis is § 102(e) / statutory or obviousness-type double patenting, not third-party anticipation.

Because all of these share the 1981-03-27 priority date, none can be § 102(b) art against '679. The only doctrinal hooks are § 102(e) (US 4,668,777 and US 4,415,732 as earlier-filed, later-published US documents, on subject matter supported in the parent) and non-statutory double patenting.

5. Category C — US patents that appear in citation tables alongside "4973679"

The following numbers recurringly appear in the same "References Cited" tables as US 4,973,679 in later patents — i.e., these are patents that cite '679, and are frequently co-listed with it. I present dates and a provisional § 102 assessment. Treat the "cited-in-'679" premise as unverified (see § 2).

Representative URLs grounding this list: https://patents.justia.com/patent/[6147200](/patent/6147200) ; http://www.everypatent.com/comp/pat6121437.html ; https://www.freepatentsonline.com/[9598458](/patent/9598458).html ; http://www.everypatent.com/comp/pat6020475.html

6. Provisional § 102 mapping (subject to the caveats in § 2)

Given the claim vocabulary visible in the record — "nucleoside," "phosphoramidites," "process according to," "blocking group," "anisylphenylmethyl," "saturated secondary amine," "silica gel" — the analysis breaks down as follows:

1. Compound claims to nucleoside phosphoramidites bearing a saturated secondary amino group (dimethylamino, diethylamino, morpholino, pyrrolidino, piperidino; see the abstract "derivatives of saturated secondary amines" and the "DESCRIPTION OF THE PREFERRED EMBODIMENTS"). No located reference anticipates these. Köster 1972, Letsinger 1976 and Amarnath/Broom 1977 all teach halo-phosphorus or phosphotriester chemistry, not carbocyclic/heterocyclic secondary-amino phosphoramidites.
2. Process claims reciting activation by a proton donor (amine hydrohalide salts; tetrazoles, imidazoles, nitroimidazoles, benzimidazoles). The patent itself states that the unsaturated nitrogen-heterocycle amidites of the parent application were known but unstable — that is an admission of the parent-family art, not of a third-party anticipation.
3. Claims to color-coded triarylmethyl blocking groups / monitoring by color (Table I; ZnBr₂ detritylation generating orange from di-p-anisylphenylmethyl). No located reference anticipates; this appears to be the genuinely novel contribution layered on the parent.
4. § 102(e) exposure from US 4,668,777 / US 4,415,732 on any claim whose subject matter is fully supported in Ser. No. 248,450 or Ser. No. 637,927 — this is the most realistic § 102-family attack, and it is a same-family attack, not third-party anticipation.

7. Bottom line

• I could not produce a verified, per-reference USPTO "References Cited" table for US 4,973,679 from the sources available in this session. Do not treat § 5 as that table.
• What I can verify from the patent text: the three specification-acknowledged prior-art items (Köster 1972; Letsinger & Lunsford 1976; Amarnath & Broom 1977), all § 102(b)-eligible but directed at halo-phosphite/phosphotriester and support chemistry rather than at the claimed saturated-secondary-amino phosphoramidites. None appears to anticipate the compound claims.
• The strongest § 102 exposure is not third-party prior art at all but the same-family US 4,668,777 / US 4,415,732 (§ 102(e) and double-patenting theory).
• To complete this properly you need the file wrapper. Retrieve it at USPTO PatentCenter for application 06/909,070 (https://patents.google.com/patent/US4973679/en links to PatentCenter and Global Dossier) and confirm (a) the exact "References Cited" list, and (b) the full text of the granted claims — which were not supplied to me and which any anticipation conclusion depends on.

I'll gather the prior-art record for this patent before analyzing. Let me run several searches in parallel.

Let me pull the claims text and check for any validity/reexamination challenges and additional prior art.

Obviousness Analysis — US 4,973,679 under 35 U.S.C. § 103

Analyst's note on sources and identifiers. This analysis is built on: (a) the authoritative full text of US4973679A supplied in the prompt (Google Patents, fetched 2026-09-30); (b) the machine-readable "Prior art keywords" field on that same page (sub; process according; nucleoside; group; anisylphenylmethyl); (c) the "Description of the Prior Art" section of the specification itself; and (d) live search results used to verify reference identities and to recover claim 1. Identifiers are reproduced literally — e.g., the record prints "oligonucleo tide" and "phosphormidite," and I do not correct these. Where a retrieved quotation contains OCR artifacts, I flag them rather than silently repairing them. This is a technical opinion, not legal advice, and it assumes pre-AIA § 103(a) governs (application filed 1986-09-18).

1. Bottom line

If the claims are not entitled to the 1981-03-27 (or at least pre-May-1981) priority date, claim 1 is in serious difficulty — arguably anticipated by the inventors' own 1981 Tetrahedron Letters publication, and in any event obvious over that publication plus the 1983–84 phosphoramidite literature. If the claims are entitled to the early date, the obviousness case is materially weaker but still substantial, resting on Letsinger & Lunsford (1976) + the commonly assigned Caruthers parent application + the art-recognized aminolysis of P(III) chlorides.

The single most important determination is therefore not a chemical one — it is which disclosure supports the "saturated secondary amino" limitation, and hence the effective filing date and § 102(b) critical date.

2. The claim as verified

The Google Patents text supplied does not include the claims. A live search recovered claim 1 from RPX Insight (https://insight.rpxcorp.com/patent/US4973679A). Reproduced with the source's OCR artifacts intact:

"1. In a process for producing oligonucleotides which comprises the step of condensing the 3'"'"'-OH or 5'"'"'-OH group of a nucleoside or oligonucleotide with a nucleoside phosphite, the improvement being that the nucleoside phosphite is a compound of one of the formulae: … wherein B is a nucleoside or deoxynucleoside base; A is H OH or OR4 in which R4 is a blocking group; R is a blocking group; R1 '"'"' is a hydrocarbyl radical containing up to about carbon atoms; and X is NR2 '"'"'R3 '"'"', wherein R2 '"'"' and R3 '"'"' taken separately each represent alkyl, aryl, aralkyl, cycloalkyl and cycloalkylalkyl containing up to 10 carbon atoms; R2 '"'"' and R3 '"'"' when taken together form an alkylene chain containing up to 5 carbon atoms in the principal chain and a total of up to 10 carbon atoms …; and R2 '"'"' and R3 '"'"' when taken together with the nitrogen atom to which they are attached form a saturated nitrogen heterocycle including at least one additional heteroatom from the group consisting of nitrogen, oxygen and sulfur."

Three points materially shape the obviousness analysis:

1. "'"' artifacts stand for prime marks — i.e., 3′-OH, 5′-OH, R1′, R2′, R3′. The dropped numeral in "containing up to about ___ carbon atoms" is 10 per the specification ("containing up to 10 carbons").
2. Claim 1 recites "aryl" in the list of separate R2′/R3′ substituents. The specification does not — it defines R2′/R3′ as "alkyl, aralkyl, cycloalkyl and cycloalkylalkyl." This is either a transcription error in the RPX record or a genuine broadening of the claim to N-aryl-N-alkyl amino groups (e.g., N-methylanilino, N-ethylanilino). This must be checked against the official claim sheet, because an N-aryl phosphoramidite is even more plainly a known organophosphorus species than a dialkylamino one.
3. Claim 1 does not require activation by a proton donor, oxidation, a support, or chain repetition. It reads on any condensation of a 3′- or 5′-OH of a nucleoside/oligonucleotide with an amidite of formulae II/IIa. That is a broad process claim whose entire point of novelty is the identity of the amino leaving group X.

The "Prior art keywords" extract — "sub," "process according," "nucleoside," "group," "anisylphenylmethyl" — is consistent with this "improvement"-form claim plus dependent claims expressly reciting the di-p-anisylphenylmethyl (DMT) blocking group, i.e., the group already in the prior art (§ 6 below).

3. Threshold issue: effective filing date, and why it decides the case

Continuity, per the specification: this application (Ser. 909,070, filed 1986-09-18) is a divisional of Ser. 637,927 (filed 1984-08-06 → US 4,668,777), which is a straight continuation of Ser. 358,589 (filed 1982-03-16, abandoned), which is a continuation-in-part of Ser. 248,450 (filed 1981-03-27 → US 4,415,732).

Because a CIP exists in the chain, the claims receive only the date of the first application that supports the saturated-secondary-amine limitation:

Two statutory nuances matter here:

• Pre-AIA § 103(c) common ownership. US 4,415,732 and US 4,668,777 are same-family, same-inventor, commonly owned (University Patents, Inc.). To the extent they qualify as prior art only under § 102(e)/(f)/(g), § 103(c) disqualifies them from use in an obviousness rejection. A challenger therefore cannot simply build the case on the parent patents.
• § 102(b) recognizes no "own work" exception. The Beaucage & Caruthers 1981 paper (Tetrahedron Lett. 22(20):1859–1862) is the inventors' own publication, but if it predates the critical date by more than a year it is a statutory bar, and § 103(c) cannot rescue the claims from it. This is the patent's principal vulnerability.

4. Level of ordinary skill in the art

A POSITA here is a synthetic organic/nucleic-acid chemist (Ph.D., or M.S./B.S. with several years' bench experience in nucleotide chemistry) familiar with: phosphite-triester coupling; P(III) chloride chemistry including aminolysis of P–Cl bonds; acyl/trityl protection of nucleoside hydroxyls and exocyclic amines; and the routine use of ³¹P-NMR and TLC. By 1981 the field was sophisticated — Khorana's phosphodiester method, Letsinger's phosphite triester, and Köster's silica/trityl work were all standard background.

5. Scope and content of the prior art (the record available on the page)

The specification's own "Description of the Prior Art" identifies the following, all of which are the "prior art section" material for this analysis:

Additional references I verified by live search, relevant conditionally:

• Beaucage & Caruthers, Tetrahedron Letters 22(20):1859–1862 (1981). The Chemical Abstracts entry for this paper states: "The title compds. I [R = NMe₂, R1 = 1-thyminyl, 1-(N-4-benzoylcytosinyl), 9-(N-6-benzoyladeninyl), 9-(N-2-isobutyrylguaninyl)] were prepd. by treatment of the 5'-protected nucleoside with MeOP(Cl)NMe₂ (CHCl₃, under N, 15 min). I are stable to normal lab. conditions but are easily activated by mild acids for coupling with nucleosides… I (R = Cl, R1 as before) was identified by NMR as the active intermediate." (Verified via the Garfield Citation Classic, http://garfield.library.upenn.edu/classics1987/A1987G060100001.pdf, and the CAS abstract reproduced in several citing works.) Note this is the same subject matter as Example I of the patent.
• Matteucci & Caruthers, J. Am. Chem. Soc. 103:3185–3191 (1981) — synthesis of deoxyoligonucleotides on a polymer support.
• McBride & Caruthers, Tetrahedron Lett. 24:245–248 (1983) — "an investigation of several deoxyribonucleoside phosphoramidites."
• Sinha, Biernat & Köster, Nucleosides & Nucleotides 3:157–171 (1984) and Nucleic Acids Res. 12:4539–4557 (1984) — deoxynucleoside-N-morpholino (and β-cyanoethyl-N,N-dialkylamino/N-morpholino) phosphoramidites on controlled-pore glass. The morpholino species is literally the third Markush alternative of claim 1 ("saturated nitrogen heterocycle including at least one additional heteroatom from … oxygen").
• The conceptual lineage is confirmed by secondary literature: the Springer Oligodeoxyribonucleotides Synthesis chapter states the phosphoramidite method "emerged as a modification of the 'phosphorodichloridite' coupling procedure reported earlier by Letsinger," via reaction of protected deoxynucleosides with chloro-(N,N-dimethylamino)methoxyphosphine (https://experiments.springernature.com/articles/10.1385/0-89603-281-7:33).

Caveat: my attempts to verify specific pre-1981 organophosphorus citations for chloro(dialkylamino)alkoxyphosphine preparation (e.g., the Nifantyev/Zwierzak aminophosphine literature) were cut off by the tool budget. I therefore do not assert any specific such citation; I rely instead on the specification's own concession that this chemistry is "art-recognized" (see § 7).

6. The "anisylphenylmethyl" / color-monitoring subject matter is plainly old

For any dependent claim reciting a triarylmethyl blocking group (DMT / di-p-anisylphenylmethyl), the prior art is overwhelming and independent of the date question:

• Köster 1972 and the parent Caruthers application already use trityl/dimethoxytrityl as the 5′-blocking group on a silica support.
• US 5,132,418 (same family) describes detritylation with 0.1 M ZnBr₂ in nitromethane, alternatives (BF₃, AlCl₃, TiCl₄, protic acids), the red-orange color observed on release of trityl from silica, and DMT monitoring at 498 nm (https://companyprofiles.justatic.com/patent/[5132418](/patent/5132418)).
• The specification itself concedes: "Most triarylmethyl groups, in present experience, have shown color production on exposure to acids."

A claim to "a triarylmethyl group that gives a distinguishable color in acid" is therefore the expected result of substituting one known arylmethyl group for another in an admitted known analytical technique. That is a classic KSR "predictable result of a known variation," rebutted only if the patentee can show the specific color assignments were unpredictable — and Table I, being routine empirical work over dozens of arylmethyl variants, tends to show the opposite (i.e., it was a matter of testing the obvious candidates).

7. Combination 1 — Letsinger (1976) + the Caruthers parent application + art-recognized aminolysis of P(III) chlorides

(This combination survives even if the claims get the earliest priority date, because each element predates 1981.)

The combination. Letsinger discloses the entire condensation/oxidation architecture of claim 1 — including the very step the claim recites ("condensing the 3′- or 5′-OH group of a nucleoside or oligonucleotide with a nucleoside phosphite"). The Caruthers parent application supplies the solid-phase environment, DMT blocking, weak-acid activation, and I₂ oxidation. What remains is the difference: replacing the reactive P–Cl with P–NR₂ where NR₂ is a saturated secondary amine.

Why a POSITA would have made the substitution — motivation:

1. Letsinger himself identified the problem the substitution solves: the nucleoside phosphorochloridite is moisture-sensitive with "extremely short shelf life," and its in-situ preparation gives the unwanted (3′–3′) dinucleoside phosphite (independent confirmation of this characterization: https://repository.ubn.ru.nl/bitstream/handle/2066/[113304](/patent/113304)/mmubn000001_029071119.pdf). The field had an express, recognized need for a coupling species that couples rapidly but survives isolation and storage.
2. Aminolysis of P(III) chlorides is textbook. Replacing the chlorine with a dialkylamino group yields an aminophosphine which, being less electrophilic, is correspondingly less susceptible to hydrolysis — while still being activated on demand by mild acid. The specification itself concedes the reaction is "art-recognized": "the new compounds of the present invention can be prepared according to art-recognized procedures such as by reaction of the selected secondary amine with the corresponding nucleoside phosphomonochloridite." An applicant's admission that the preparative route is conventional is powerful § 103 evidence.
3. The amine functions as a leaving group, not a participant. The patent explains the mechanism: the amidite is "activated by acidic compounds through protonation." The 1981 Beaucage & Caruthers work confirmed by NMR that the active intermediate is the chloro species. If the amine is merely a masked/protected form of the reactive P–Cl, then which amine is used is a selection among known leaving groups, judged by basicity, steric bulk, and stability — i.e., routine optimization of a recognized design variable.

Reasonable expectation of success: high. The transformation is a single, mild substitution on P(III); the products are a known class of organophosphorus compounds; and the members of the claimed amine genus (dimethylamino, diethylamino, diisopropylamino, dibutylamine-derived, methylpropyl-, methylhexyl-, methylcyclopropyl-, ethylcyclohexyl-, methylbenzyl-, morpholino, thiomorpholino, pyrrolidino, piperidino, 2,6-dimethylpiperidino, piperazino) are a homologous/analogous series performing the identical function. Members of an analogous series with the same utility are ordinarily obvious.

KSR rationales available to a challenger: (i) combination of familiar elements (Letsinger's coupling + a known P–NR₂ species) yielding a predictable result; (ii) substitution of one known element for another (amine for chlorine) to obtain a predictable result (greater hydrolytic stability); (iii) use of a known technique (amine displacement) to improve a similar process in the same way; and (iv) "obvious to try" — a finite number of identified, predictable amine candidates with a reasonable expectation of success.

8. Combination 2 — The inventors' own 1981 Tetrahedron Letters paper (conditional on effective date)

If the claims are entitled only to 1984-08-06 or 1986-09-18, the Beaucage & Caruthers paper is § 102(b) art and the § 103 question is nearly moot for the disclosed species:

• The paper discloses preparation of the identical compounds (R = NMe₂) from MeOP(Cl)NMe₂, depicts the four protected bases (thyminyl, N-4-benzoylcytosinyl, N-6-benzoyladeninyl, N-2-isobutyrylguaninyl) — matching patent Example I (compounds I–IV) — and teaches that the amidites are "stable to normal lab. conditions" yet "easily activated by mild acids for coupling with nucleosides," with the coupling demonstrated against 3′-O-levulinylthymidine, which is Example I-A/B of the patent.
• Dimethylamino falls squarely within "R2′ and R3′ taken separately … alkyl … containing up to 10 carbon atoms." That is anticipation of at least that species under § 102(b), and it makes the remainder of the genus obvious: the paper teaches the genus's operability, and the remaining members differ only in the identity of a leaving group.
• Because the paper also identifies the chloro intermediate as the active species, it supplies the very mechanistic rationale ("the amine is just a masked chloride") that renders the broader amine selection obvious.

Caveat: whether the paper is § 102(b) art is entirely a function of the priority/support analysis in § 3. If the claims carry a 1981 or 1982 date, this combination collapses — which is precisely why the priority determination is the decisive issue.

9. Combination 3 — Beaucage 1981 + Matteucci 1981 + McBride 1983 + Sinha/Köster 1984

If the 1986-09-18 date controls, this combination is close to dispositive:

• Beaucage & Caruthers 1981 — stable dialkylamino amidites, mild-acid activation.
• Matteucci & Caruthers 1981 — the same amidite chemistry applied to solid-phase synthesis of deoxyoligonucleotides (supplies the process context of the claim's preamble).
• McBride & Caruthers 1983 — "an investigation of several deoxyribonucleoside phosphoramidites," i.e., explicit optimization of the amine variable.
• Sinha, Biernat & Köster 1984 — N-morpholino and N,N-dialkylamino phosphoramidites on porous glass, i.e., the claim-1 Markush alternatives themselves, plus 2,6-dimethylpiperidine- and piperazine-type saturated heterocycles elsewhere in the amidite literature.

Motivation is supplied by all four: the need for storage-stable, isolable, acid-activatable amidites and for higher coupling yields on solid supports. Result: claim 1's genus is the aggregate of the prior art's disclosed species.

10. What the patentee will argue, and how strong it is

Non-obviousness arguments available:

1. Teaching away / criticality of the amine class. The patent frames the prior art as deliberately using unsaturated nitrogen heterocycles (tetrazole, imidazole, benzimidazole, indole) because of their "extremely high reactivity," and characterizes the saturated amines as a different, deliberately less reactive class. A POSITA following that express teaching would not have selected saturated amines — and the inventors' own earlier application contains that teaching. This is the patent's strongest argument, because it is a genuine "teach away" grounded in the inventors' prior disclosure plus a real property trade-off (reactivity vs. stability).
   • Rebuttal: if the 1981 Beaucage & Caruthers paper is prior art, it destroys this argument outright, because it discloses the dimethylamino amidite as a working, stable, acid-activatable species. Even if not prior art, the specification's own admission that saturated amines react "readily with unblocked 3′-OH or 5′-OH of nucleosides under normal conditions" undercuts the claim of unexpected operability.
2. Unexpected results. The stability/isolation advantage (isolable dry powders, room-temperature storage, <4% (3′-3′) byproduct vs. the prior phosphite procedure) is a real and documented improvement.
   • Rebuttal: the expectation of improved hydrolytic stability from replacing an electrophilic P–Cl with a less electrophilic P–NR₂ is inherent in the chemistry and therefore not "unexpected" in the KSR sense. The specific ³¹P-NMR purity figure is a routine optimization measurement.
3. Commercial success / long-felt need. Undeniably potent as narrative: this chemistry became the industry standard for DNA synthesis, with the commercial value concentrated in the Caruthers family (see, e.g., the Brock University thesis noting that the method "became the industry standard" and that ABI held an exclusive license — https://dr.library.brocku.ca/bitstream/handle/[10464/3377](https://assignmentcenter.uspto.gov/search/patent/reelFrameDetail?reelFrame=10464-3377)/Brock_Tram_Kha_2011.pdf).
   • Rebuttal: nexus is the weak point. The commercial dominance reflects the entire family (US 4,415,732; 4,458,066; 4,500,707; 4,668,777; 4,973,679; 5,132,418 — a chain cited together in WO2004039469A2), the solid-support architecture, DMT monitoring, and later β-cyanoethyl/phosphorothioate developments. Success attributable to features other than the saturated-amine selection does not rebut obviousness of claim 1.

Net assessment: the teaching-away argument is real but fragile — it depends entirely on (i) winning the early priority date and (ii) keeping the 1981 paper out as prior art. If either fails, the argument is largely neutralized.

11. Overall conclusion

Decisive factual questions a challenger should resolve first:

1. Does the 1981 application (Ser. 248,450 / US 4,415,732) support the "saturated secondary amino" limitation? Examine the specification of US 4,415,732 for disclosure of X = NR₂′R₃′ where the amine is saturated. If it is absent, the entire CIP chain gives at most a 1982-03-16 date, and (if first appearing only in the 1984 application) a 1984-08-06 date.
2. What is the exact publication date of the 1981 Tetrahedron Letters paper? The one-year grace window turns on whether it was published before or after the critical date.
3. Does claim 1 actually recite "aryl" among the separate R2′/R3′ groups? If yes (rather than being an RPX transcription error), the claim reaches N-aryl-N-alkyl aminophosphines, which broadens the obviousness exposure considerably — and conflicts with the specification's narrower definition, raising a § 112(a) written-description question that bears on the effective date as well.
4. What do dependent claims 2+ recite? My verification covers only claim 1. If dependents claim the triarylmethyl color-coded monitoring, § 6 above shows those features are old in substance.

Confidence: high on the reference content, the continuity chain, claim 1's wording (subject to the three flagged artifacts), the general legal framework, and the date-dependency of the analysis. Lower on the exact § 102(b) date of the 1981 paper; on whether "aryl" genuinely appears in the issued claim; on the full claim set; and on the pre-1981 organophosphorus art for chloro(dialkylamino)alkoxyphosphines, for which I could not complete verification within the available tool budget and for which I therefore assert no specific citation.