DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Election/Restrictions
Applicant’s election without traverse of Group I (claims 1-8, 24-25, 30, 35, 38-39, 44 in the reply filed on 8 June 2026 is acknowledged.
Claims 45, 53-54 withdrawn from further consideration pursuant to 37 CFR 1.142(b). Election was made without traverse in the reply filed on 8 June 2026.
Claim Rejections - 35 USC § 102
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1, 4, 39, and 44 is/are rejected under 35 U.S.C. § 102(a)(1) as being anticipated by Braunschweig et al., (“Braunschweig”).
As to claim 1, the claim recites a compound comprising the depicted borole in combination with M+, wherein, inter alia, X¹ may be null; Ra, Rb, Rc, and Rd may independently be aryl; M+ is a cation providing electronic balance; and one expressly recited alternative requires Z to be a carbene and Z* to be absent.
Braunschweig expressly discloses preparation of the SIMes adduct of 1-chloro-2,3,4,5-tetraphenylborole by combining the borole and SIMes in benzene. Thus, Braunschweig's starting borole contains four phenyl substituents, each of which falls within the claimed “aryl” alternative. Braunschweig, p. 2041, right column, first full paragraph following the introductory discussion and Scheme 1.
Braunschweig further discloses reduction of this carbene-borole compound with excess KC8 in diethyl ether to afford monoanionic derivative 2 in 37% yield. Braunschweig specifically characterizes compound 2 as an “NHC-stabilized boryl anion,” with the boron lone-pair electrons residing in a π-bonding orbital and being stabilized by delocalization over the C4B ring. Braunschweig, p. 2041, right column, paragraph beginning “Reduction of 1 with excess KC8….”
Braunschweig further states that compound 2 crystallizes as a potassium-bridged dimer. Braunschweig, p. 2041, last paragraph. The crystallographic discussion specifies that, within the dimeric unit, “the potassium cation resides above one of the borole rings” and interacts with the borole framework. Braunschweig, p. 2042, left column, first full paragraph. Thus, Braunschweig expressly discloses the countercation necessary to provide electronic balance to the monoanionic borole.
Braunschweig's electronic-structure analysis further establishes that the NHC is bonded to the boron center. The HOMO analysis shows π-like bonding between the boron atom and carbene carbon and identifies the NHC as both a strong σ donor and a π acceptor that delocalizes electron density from boron. Braunschweig, p. 2042, left-to-right column discussion accompanying Figure 2.
Accordingly, compound 2 of Braunschweig discloses in a single species: (1) a C4B borole corresponding to the X¹=null alternative; (2) four phenyl substituents falling within the claimed aryl definitions; (3) a carbene coordinated to boron; (4) a monoanionic borole/boryl electronic structure; and (5) K+ as a charge-balancing cation. Because claim 1 broadly encompasses this disclosed species, claim 1 is anticipated.
As to claim 4, claim 4 further requires X¹ to be null. Braunschweig expressly characterizes compound 2 as possessing a C4B borole ring. The C4B ring contains no intervening O, NRn, or additional carbon-bridging group at the position represented by X¹ in claim 1 and therefore corresponds to the X¹=null alternative. Claim 4 is consequently anticipated by the same compound 2.
As to claim 39, claim 39 further limits M+ to a group that includes an alkali cation. Braunschweig expressly identifies compound 2 as potassium-bridged and expressly identifies the “potassium cation” positioned above the borole ring. Potassium is an alkali metal; therefore, the alkali-cation alternative of claim 39 is expressly satisfied.
As to claim 44, claim 44 excludes the single specifically depicted IPr-containing potassium borafluorene compound. Braunschweig's anticipating species is instead an SIMes-stabilized 2,3,4,5-tetraphenylborole monoanion. Braunschweig expressly identifies the tetraphenylborole/SIMes starting structure and the resulting monoanion 2. Because Braunschweig's compound 2 is not the single compound excluded by claim 44 and otherwise remains within the genus of claim 1, the negative limitation does not distinguish claim 44 from Braunschweig. Claim 44 is therefore anticipated.
NOTE: Claim 24 — additional rejection under the expressly stated interpretation
Claim 24 is additionally rejected under 35 U.S.C. § 102(a)(1) as being anticipated by Braunschweig, for purposes of prior-art examination under the following expressly stated interpretation.
Claim 24 depends from claim 1 and recites that “Z and Z* form a diaminocarbene or a heteroamino carbene.” For purposes of this prior-art rejection, that language is construed as requiring the borole to be stabilized by a diaminocarbene or heteroaminocarbene ligand. The separate inconsistency between this recitation and claim 1's recitation that “Z is a carbene and Z* is absent” remains subject to the § 112 rejection of record.
Braunschweig identifies its ligand as SIMes, an N-heterocyclic carbene, and identifies the starting material as the SIMes adduct of 1-chloro-2,3,4,5-tetraphenylborole. Braunschweig, p. 2041, Scheme 1 and accompanying first full paragraph. The SIMes structure shown in Scheme 1 is an imidazolidin-2-ylidene carbene in which the carbene carbon is flanked by two nitrogen atoms. Reduction then yields the isolated SIMes-stabilized monoanion 2. Braunschweig, p. 2041, paragraph beginning “Reduction of 1 with excess KC8….”
Under the stated interpretation of “diaminocarbene,” the SIMes-stabilized compound 2 therefore satisfies the additional limitation of claim 24. Claim 24 is anticipated by Braunschweig.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 2, 3, and 8 is/are rejected under 35 U.S.C. § 103 as being unpatentable over Braunschweig in view of Grigsby and Power, “Isolation and Reduction of Sterically Encumbered Arylboron Dihalides: Novel Boranediyl Insertion into C–C σ-Bonds,” J. Am. Chem. Soc. 1996, 118, 7981–7988 (“Grigsby”), and further in view of Yang et al., “Persistent Borafluorene Radicals,” Angew. Chem. Int. Ed. 2020, 59, 3850–3854 (“Yang”).
Braunschweig discloses the carbene-stabilized, potassium-balanced borole monoanion underlying claim 1 for the reasons set forth in the § 102 rejection above. In particular, Braunschweig isolates an NHC-stabilized borole monoanion by KC8 reduction and establishes the stabilizing σ-donor/π-acceptor interaction of the NHC with electron-rich boron. Braunschweig, p. 2041, paragraph beginning “Reduction of 1 with excess KC8…” and p. 2042, electronic-structure discussion.
Claims 2 and 3 further require the fused borafluorene-type framework depicted in those claims. Claim 2 includes several alternative fused structures, including the all-carbon borafluorene framework, and claim 3 further restricts the compound to the specifically depicted all-carbon fused borafluorene structure.
Grigsby expressly teaches that the 9-borafluorenyl framework was reductively accessible before the effective filing date. Grigsby's p. 7981 Abstract reports that lithium-metal treatment of arylboron dibromide 2 in diethyl ether afforded lithium 9-borafluorenyl compounds 4 and 5, in which boron is incorporated into a delocalized five-membered borafluorenyl ring. The same Abstract reports that reduction with KC8 afforded 9-borafluorenyl “ate” compounds 6 and 7. Grigsby, p. 7981, Abstract, sentences 2–5.
The Examiner does not rely on Grigsby as disclosing the presently claimed carbene-stabilized monoanion. Grigsby expressly reports that its KC8 products 6 and 7 underwent hydrogen addition at boron, producing borate salts. Grigsby, p. 7981, Abstract, sentences following the disclosure of compounds 6 and 7. Rather, Grigsby establishes that the exact fused 9-borafluorenyl skeleton was known to undergo alkali-metal and KC8 reduction and to furnish lithium- and potassium-containing reduced boron species.
Yang supplies the direct connection between that fused borafluorene skeleton and carbene stabilization. Yang reports that NHC- and CAAC-stabilized borafluorene radicals were isolated. More specifically, the paragraph beginning “The stabilizing ability of the strongly σ-donating and π-accepting CAAC ligand…” reports reduction of a 9-bromo-9-borafluorene–CAAC adduct with one equivalent KC8 in toluene at room temperature to afford CAAC-stabilized borafluorene radical 2 in 69% isolated yield, and corresponding KC8 reduction of the NHC adduct to afford NHC-stabilized radical 4 in 47% isolated yield. Yang, p. 3851, paragraph immediately following the introductory discussion and Scheme 1.
Yang further establishes access to the corresponding anionic states. The cyclic-voltammetry paragraph beginning “To gain insight into the redox properties of 2 and 4…” reports reversible reduction waves at E1/2 = −1.82 V and −2.25 V for the CAAC- and NHC-supported compounds, respectively, thereby demonstrating formation of their anionic states on the electrochemical timescale. Yang, p. 3852, paragraph accompanying Figure 6. Yang expressly attributes the lower reduction potential of the CAAC species to the greater π-accepting ability of CAAC.
It would have been obvious to a person of ordinary skill before the effective filing date to employ the known fused borafluorene skeleton of Grigsby and Yang in the carbene-stabilized anionic borole system of Braunschweig. The reason to make the modification is supplied by the references themselves: Grigsby demonstrates that the fused borafluorenyl skeleton undergoes alkali-metal reduction; Yang demonstrates that the same borafluorene skeleton accepts both NHC and CAAC ligands and survives KC8 reduction as isolated carbene-stabilized reduced species; and Braunschweig demonstrates that carbene stabilization permits isolation of a closely related borole monoanion.
There also would have been a reasonable expectation of success. The proposed modification does not depend on an assumption that arbitrary boron heterocycles behave alike. The skilled artisan had three concrete experimental demonstrations: Grigsby's reduced alkali-metal borafluorenyl species, Yang's isolated NHC- and CAAC-borafluorene reduction products, and Braunschweig's isolated NHC-borole monoanion.
The Examiner has considered Yang's express statement that the further reduced anions were “chemically unstable under specified conditions.” Yang, p. 3852, paragraph accompanying Figure 6. The same paragraph, however, states that the anionic species were stable on the electrochemical timescale and were observed as reversible reduction waves. That disclosure does not amount to a teaching that carbene-stabilized borafluorene anions could not be obtained under other conditions, particularly in view of Braunschweig's actual isolation of the closely related carbene-stabilized borole monoanion. The evidence therefore supports a reasonable expectation of success, although not absolute predictability, which is all § 103 requires.
With respect to claim 8, claim 8 recites that R1a, R2a, and R3a are each hydrogen, although those variables are introduced in claim 2 while claim 8 presently depends directly from claim 1. For purposes of prior-art examination, claim 8 is interpreted as requiring hydrogen at the corresponding R1a, R2a, and R3a positions of the fused borafluorene structure shown in claim 2; the dependency/antecedent-basis defect is addressed separately under § 112. Yang's compounds are prepared from 9-bromo-9-borafluorene, i.e., the otherwise unsubstituted borafluorene ring system, and therefore provide hydrogen at the corresponding aromatic positions. Yang, p. 3851, Scheme 1 and paragraph beginning “The stabilizing ability….”
Claim 5 — Braunschweig in view of Numata and further in view of Yang
Claim 5 is rejected under 35 U.S.C. § 103 as being unpatentable over Braunschweig in view of Numata, Yasuda, and Adachi, “High Efficiency Pure Blue Thermally Activated Delayed Fluorescence Molecules Having 10H-Phenoxaborin and Acridan Units,” Chem. Commun. 2015, 51, 9443–9446 (“Numata”), and further in view of Yang.
Claim 5 depends from claim 1 and requires X¹ to be O. Braunschweig teaches the underlying carbene-stabilized borole monoanion but does not disclose the oxygen-bridged X¹ member.
Numata expressly reports synthesized molecules containing the 10H-phenoxaborin framework. Numata, p. 9443, title and Abstract. The publication states that molecules “having 10H-phenoxaborin and acridan units” were obtained and evaluated. Thus, before the effective filing date, an O-bridged fused boron framework corresponding structurally to the X¹=O class was an established isolable boron heterocycle.
Yang supplies evidence that moving from an unfused borole to a fused boron framework did not destroy carbene coordination or reductive accessibility. Yang actually isolates both CAAC- and NHC-supported fused borafluorene radicals after KC8 reduction and observes reversible access to their anionic states. Yang, p. 3851, Scheme 1 and synthesis paragraph; p. 3852, Figure 6 discussion.
It would have been obvious to use the known O-bridged phenoxaborin framework of Numata as the X¹=O member of the broader fused boron platform in the carbene-stabilized reduction chemistry taught by Braunschweig and Yang. The reason to make the modification is not merely that oxygen is a conventional heteroatom; Numata establishes the actual O-bridged boron framework as an isolable compound class, while Yang demonstrates that fused boron frameworks can retain carbene coordination and undergo KC8 reduction.
A reasonable expectation of success was supported by those experimental teachings: Numata establishes the viability of the O-bridged boron core, Braunschweig establishes stabilization of electron-rich borole by NHC, and Yang establishes carbene stabilization and reduction of a fused boron framework.
Claim 6 — Braunschweig in view of Xie
Claim 6 is rejected under 35 U.S.C. § 103 as being unpatentable over Braunschweig in view of Xie, Zhang, and Cui, “2-Chloro-Azaborolyl Anion: A Source of 1,2-Azaborole Isosteric to Cyclopentadienylidene,” Chem. Eur. J. 2014, 20, 9500–9503 (“Xie”).
Claim 6 depends from claim 1 and requires X¹ to be NRn. Braunschweig provides the carbene-stabilized, potassium-balanced borole monoanion but does not disclose the NRn ring member.
Xie expressly identifies azaborolyl anions as five-membered BN heterocycles. The Abstract reports reduction of an azabutadienyl-chelate boron dichloride with two equivalents of potassium to afford a novel 2-chloro-azaborolyl anion as a stable product in good yield. The same Abstract further reports that reaction of the potassium azaborolyl anion with 1,3,4,5-tetramethylimidazol-2-ylidene, an NHC, afforded the first NHC–azaborole adduct with elimination of KCl. Xie, p. 9500, Abstract, sentences 1 and 3–4. (PubMed)
It would have been obvious to employ the nitrogen-containing azaborole framework taught by Xie in the carbene-stabilized borole chemistry of Braunschweig because Xie expressly demonstrates that the BN analogue possesses both properties material to the proposed modification: formation of a stable potassium anion and compatibility with an NHC.
There would also have been a reasonable expectation of success because Xie did not merely identify the nitrogen analogue conceptually. Xie actually isolated the potassium azaborolyl anion and actually converted that material into an NHC–azaborole adduct. Braunschweig separately actually isolated an NHC-supported borole monoanion. Thus, both the nitrogen-containing anion and NHC compatibility had been experimentally established before the filing date.
Claim 7 — Braunschweig in view of Wood and further in view of Yang
Claim 7 is rejected under 35 U.S.C. § 103 as being unpatentable over Braunschweig in view of Wood, Piers, Keay, and Parvez, “Spirocyclic Boronium Ions: Precursors to Persistent Neutral Radicals,” Chem. Commun. 2009, 5147–5149 (“Wood”), and further in view of Yang.
Claim 7 requires X¹ to be the specifically depicted carbon-bridged group.
Wood expressly discloses boronium ions “based on the 9-bora-9,10-dihydroanthracene scaffold” and reports that these cations are convenient starting materials for persistent neutral radicals having significant spin density on boron. Wood, p. 5147, Abstract. Wood therefore establishes both the claimed type of carbon-bridged boron scaffold and its ability to support reduced boron-centered electronic states.
Yang independently establishes that a closely related fused boron scaffold accepts NHC and CAAC ligands and undergoes KC8 reduction to persistent carbene-supported borafluorene radicals. Yang, p. 3851, synthesis paragraph and Scheme 1. 4
A person of ordinary skill would have had reason to employ the carbon-bridged boron scaffold of Wood in the carbene-stabilized borole system of Braunschweig because Wood establishes that this scaffold accommodates substantial boron-centered electron density, while Yang establishes that analogous fused boron frameworks remain compatible with carbene ligation and reduction.
A reasonable expectation of success follows from the actual chemistry reported in each reference: Wood obtains reduced radical species based on the carbon-bridged scaffold; Yang obtains persistent carbene-bound reduced fused-boron species; and Braunschweig isolates a carbene-stabilized borole monoanion. The proposed modification therefore follows an experimentally supported progression rather than a bare assertion of structural interchangeability.
Claim 25 — Braunschweig in view of Yang
Claim 25 is rejected under 35 U.S.C. § 103 as being unpatentable over Braunschweig in view of Yang.
Claim 25 depends from claim 24 and further restricts the carbene to one of the two depicted heterocyclic carbene frameworks, with X² defined as O, S, or C(RL4)2 and X³ defined as NL2, O, or S, together with the recited substituent definitions. At least the X²=C(RL4)2 alternative encompasses a cyclic (alkyl)(amino)carbene-type framework.
Braunschweig establishes that carbene coordination stabilizes an isolable borole monoanion and identifies the electronic origin of the stabilization as combined σ donation and π acceptance. Braunschweig, pp. 2041–2042.
Yang expressly teaches both cyclic (alkyl)(amino)carbene (CAAC)- and N-heterocyclic-carbene (NHC)-stabilized borafluorene systems. Yang's Abstract identifies both ligand classes, and the synthesis paragraph reports isolation of the CAAC-supported product in 69% yield and NHC-supported product in 47% yield after KC8 reduction. Yang, Abstract and p. 3851, Scheme 1 discussion.
A person of ordinary skill therefore would have had reason to select a CAAC-type heterocyclic carbene encompassed by claim 25 for the borole-anion system of Braunschweig because Yang expressly demonstrates that CAAC and NHC ligands provide alternative, experimentally successful carbene-stabilization platforms for reduced fused-boron species.
The reasonable expectation of success is supported by actual isolation of the carbene-stabilized species in both references rather than by an assumption of “routine optimization.” Moreover, Yang establishes that CAAC possesses stronger σ-donating and π-accepting interactions than the comparative NHC, providing a specific electronic reason for using that carbene class. Yang, discussion preceding the cyclic-voltammetry paragraph.
Claim 30 — Braunschweig in view of Yang and further in view of Hagspiel
Claim 30 is rejected under 35 U.S.C. § 103 as being unpatentable over Braunschweig in view of Yang and further in view of Hagspiel et al., “Reduction of a Dihydroboryl Cation to a Boryl Anion and Its Air-Stable, Neutral Hydroboryl Radical Through Hydrogen Shuttling,” Chem. Sci. 2020, 11, 551–555 (“Hagspiel”).
Claim 30 depends from claim 24 and requires the specifically depicted cyclic alkyl(amino)carbene-type structure, wherein L3 is selected from aryl and C1–8 alkyl.
Braunschweig provides the underlying carbene-stabilized borole monoanion but employs SIMes rather than the claimed CAAC-type ligand.
Yang directly teaches the use of CAAC on the relevant fused-boron framework. Yang reports reduction of a 9-bromo-9-borafluorene–CAAC adduct with one equivalent KC8 in toluene at room temperature to give isolated CAAC-stabilized borafluorene radical 2 in 69% yield. Yang, p. 3851, paragraph beginning “The stabilizing ability….” Yang further reports reversible access to the CAAC-supported anionic state at E1/2 = −1.82 V and expressly attributes the lower reduction potential relative to the NHC compound to CAAC's greater π-accepting ability. Yang, p. 3852, paragraph accompanying Figure 6.
Hagspiel provides even more direct evidence that a CAAC can stabilize an isolable boron anion. Hagspiel, p. 551, Introduction, first paragraph, states that CAACs had become ligands of choice for stabilizing low-oxidation-state main-group compounds because of their strong σ-donor and π-acceptor properties and specifically identifies prior successful use of CAACs with boryl radicals, boryl radical cations, boryl anions, and B(I) compounds. Hagspiel's p. 551 Abstract further reports that the bis-CAAC-supported dihydroboryl cation underwent facile two-electron reduction with KC8 to yield a stable hydroboryl anion.
It would therefore have been obvious to substitute the CAAC-type ligand taught by Yang and Hagspiel for the NHC of Braunschweig. The references provide a specific technical reason: CAAC's σ-donor/π-acceptor properties stabilize electron-rich low-valent boron, Yang demonstrates that effect directly on a borafluorene framework, and Hagspiel demonstrates an isolable CAAC-supported boron anion.
There also would have been a reasonable expectation of success because Braunschweig actually isolates a carbene-stabilized borole monoanion, Yang actually isolates a CAAC-supported borafluorene reduction product and demonstrates further reversible reduction to the anionic state, and Hagspiel actually isolates a stable CAAC-supported boron anion following KC8 reduction. These successful experiments provide substantially more than a generalized expectation that a different carbene “might work.”
Claim 35 — Braunschweig in view of Chen
Claim 35 is rejected under 35 U.S.C. § 103 as being unpatentable over Braunschweig in view of Chen and Cui, “Reactivity of the 2-Chloroazaborolyl Anion,” Eur. J. Inorg. Chem. 2017, 4480–4484 (“Chen”).
Claim 35 depends from claim 1 and requires Z and Z* together to form the depicted O,O-containing aromatic ring, with RZ1–RZ4 selected from the recited substituent classes.
Braunschweig establishes an electron-rich nucleophilic borole anion. Its HOMO analysis identifies a π-nucleophilic boron center, and experimental methylation with MeI establishes nucleophilic reactivity at boron. Braunschweig, p. 2042, electronic-structure discussion and methylation paragraph. Braunschweig's conclusion expressly states that compound 2 contains a nucleophilic boron atom that reacts cleanly with the electrophile MeI. Braunschweig, p. 2043, conclusion.
Chen directly teaches capture of an anionic boron heterocycle by an ortho-quinone. Chen's Abstract identifies potassium 2-chloroazaborolyl anion 1 and reports oxidative cycloaddition upon reaction with ortho-quinone. More specifically, the Results and Discussion paragraph immediately preceding Scheme 4 states that reaction of anion 1 with 3,5-di-tert-butyl-ortho-quinone affords cyclic oxidative-cycloaddition product 4 as a light-yellow solid in 67% yield. Scheme 4 identifies product 4 as the corresponding cyclic O,O boron product.
It would have been obvious to react the electron-rich anionic boron species of Braunschweig with an ortho-quinone of the type taught by Chen to provide the O,O-bound cyclic boron structure encompassed by claim 35. The motivation is supplied by Chen's directly demonstrated reactivity rather than by a general assertion that oxygen ligands are interchangeable.
A reasonable expectation of success was likewise present because Chen actually performed the relevant reaction between an anionic boron heterocycle and an ortho-quinone and isolated the cyclic oxidative-cycloaddition product in 67% yield. Braunschweig separately establishes an isolable nucleophilic borole anion. Thus, both the reactive anionic-boron state and its successful trapping by an ortho-quinone were experimentally demonstrated.
Claim 38 — Braunschweig in view of Chen and further in view of Hickson
Claim 38 is rejected under 35 U.S.C. § 103 as being unpatentable over Braunschweig in view of Chen and further in view of Hickson et al., “The Semiquinone Radical Anion of 1,10-Phenanthroline-5,6-dione: Synthesis and Rare Earth Coordination Chemistry,” Chem. Commun. 2018, 54, 11284–11287 (“Hickson”).
Claim 38 depends from claim 1 and requires Z and Z* together to form one of the two depicted fused O,O-containing heteroaromatic systems. The first expressly depicted alternative is the phenanthroline-derived O,O system.
Braunschweig establishes the nucleophilic borole-anion starting point, while Chen establishes the pertinent oxidative cycloaddition of an anionic boron heterocycle with an ortho-quinone to form a cyclic O,O-bound boron product. Braunschweig, pp. 2042–2043; Chen, Results and Discussion, paragraph immediately preceding Scheme 4.
Hickson supplies the particular fused ortho-dione framework. Hickson's Abstract expressly concerns reduction of 1,10-phenanthroline-5,6-dione and formation of its semiquinone radical anion. More particularly, Hickson, p. 11284, paragraph beginning “Phenanthroline dione (pd) is a commercially available…,” identifies 1,10-phenanthroline-5,6-dione as a redox-active ligand having a three-member electron-transfer series in which the neutral compound undergoes sequential one-electron reductions to monoanionic and dianionic forms. The same paragraph states that, in the dianionic state, the O,O′ pocket is a π-donating diolate analogous to a catecholate.
It would have been obvious to employ the 1,10-phenanthroline-5,6-dione taught by Hickson as the ortho-dione reagent in Chen's demonstrated oxidative-cycloaddition reaction with an anionic boron heterocycle. Chen identifies the successful reaction class—capture of an electron-rich boron anion with an ortho-quinone—while Hickson identifies the particular fused ortho-dione required by the claim and establishes its adjacent O,O redox-active/catecholate-like chemistry.
There also would have been a reasonable expectation of success. Chen demonstrates actual cycloaddition between an anionic boron heterocycle and an ortho-quinone, while Hickson demonstrates that 1,10-phenanthroline-5,6-dione possesses the requisite adjacent redox-active O,O functionality and remains structurally defined through reduction. Thus, the substitution is based on demonstrated common chemical functionality rather than merely superficial structural similarity.
Because claim 38 is drafted in the alternative, it is sufficient that the combination renders obvious the expressly depicted phenanthroline-derived alternative; the references need not independently render obvious every X4=O, S, or NRZn alternative.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-8, 24-25, 30, 35, 38-39, 44 rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the enablement requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
Claim 1 encompasses several materially different boron-ring systems because X¹ may be null, O, NRn, or the recited carbon-bridging unit. It also independently permits Ra–Rf and Rn to vary among alkyl, aryl, heteroaryl, and heterocyclyl groups, allows multiple substituents to join to form additional rings, permits materially different stabilizing groups at Z/Z*, and broadly defines the charge-balancing cation. The specification expressly confirms these chemically distinct X¹ alternatives. Claims 2–7 further encompass heteroannulated and differently bridged borole frameworks rather than limiting the invention to the experimentally demonstrated borafluorene core.
The working examples, by contrast, are concentrated principally on a narrow borafluorene system. Example 1 prepares EtCAAC and IPr adducts of 9-bromo-9-borafluorene, and the subsequent reduction examples primarily vary Li, Na, or K reducing conditions on those borafluorene precursors. The specification does not provide corresponding working examples establishing preparation and isolation throughout the X¹=O, X¹=NRn, carbon-bridged, extensively aza-annulated, or broadly substituted genera encompassed by claims 1–8.
The specification itself demonstrates that this is not a chemically predictable field in which the disclosed conditions can simply be extrapolated across the entire genus. In Example 5, the disclosed compound is described as “highly reactive,” rapidly converts to a hydridoborafluorene, and use of excess reducing agent causes NHC-ligand activation and a mixture of products, such that carefully controlled stoichiometry is necessary for isolation. Example 11 likewise produces an inseparable mixture containing unidentified products. These disclosures demonstrate sensitivity to ligand structure, reductant, stoichiometry, and reaction pathway.
Application of the Wands factors supports a conclusion of undue experimentation:
First, the breadth of the claims strongly favors nonenablement. The claims encompass large structural genera generated from multiple independent choices of borole core, annulation pattern, heteroatom identity, carbene or O,O stabilization group, substituent identity, countercation, and sequestration ligand.
Second, the nature of the invention and predictability of the art favor nonenablement. The claimed compounds are low-valent, electron-rich boron anions whose stability and reaction pathway depend materially on ligand electronics, ring structure, reducing agent, counterion, solvent, and stoichiometry. The application's own examples demonstrate hydride formation, ligand activation, and unidentified side products when those variables are altered.
Third, although the level of skill in the art is relatively high and the prior art provides some guidance concerning borole, borafluorene, carbene, and boryl-anion chemistry, that factor does not establish a general predictive rule by which the skilled artisan could determine in advance which of the very large number of claimed combinations will form an isolable stabilized anion.
Fourth, the quantity of guidance and representative examples is limited relative to the scope claimed. The specification expressly enumerates numerous structural alternatives and exemplary carbenes, but enumeration of possible structures does not supply reaction conditions or a structure-reactivity relationship enabling the ordinary artisan to obtain stable anions across those chemically diverse classes.
Fifth, the quantity of experimentation required is substantial. For each materially different core/ligand combination the artisan would be required to identify or synthesize a precursor, select a carbene or chelating species, select reductant and equivalents, select solvent and temperature, determine counterion/sequestration conditions, and determine purification and isolation conditions while screening for competing hydride formation, ligand activation, decomposition, or alternate products.
Accordingly, notwithstanding the enabled working species, the disclosure does not provide sufficient guidance to permit practice throughout the full scope of claims 1–8, 24–25, 30, 35, 38–39, and 44 without undue experimentation.
The dependent claims do not cure the defect. Claims 4–7 narrow only X¹ while retaining the extensive substituent, ligand, ring-forming, and cation variability of claim 1. Claims 24, 25, and 30 restrict the carbene class but retain the broad borole-core and substituent scope. Claims 35 and 38 select O, O stabilizing systems but retain broad structural variability in the borole portion. Claim 39 principally restricts the cationic component, and claim 44 only excludes one compound. Thus, substantial portions of the unenabled genus remain within each dependent claim.
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 8, 24-25, 30, 39 rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 8 is rejected as being indefinite because the recitations “R1a,” “R2a,” and “R3a” lack antecedent basis in claim 1, from which claim 8 directly depends.
Claim 1 defines Ra, Rb, Rc, Rd, Re, Rf, and Rn, but does not define R1a, R2a, or R3a. Those designations first appear in the structures and definitions of claim 2. Nevertheless, claim 8 depends directly from claim 1 and states that “R1a, R2a, and R3a are each hydrogen.”
It is therefore unclear which atoms or substituent positions in the compound of claim 1 are required to be hydrogen. The defect is substantive rather than merely formal because different interpretations produce different compound scopes. Claim 8 consequently fails to particularly point out and distinctly claim the invention.
For purposes of the prior-art rejection above, claim 8 has been interpreted as referring to the corresponding R1a, R2a, and R3a positions of claim 2. That interpretation does not cure the § 112(b) defect.
Claims 24, 25, and 30 are rejected as indefinite because the relationship between Z and Z* required by claim 24 conflicts with the limitation inherited from claim 1.
Claim 1 states that “Z is a carbene and Z* is absent,” as one alternative. Claim 24, while depending from claim 1, states instead that “Z and Z* form a diaminocarbene or a heteroamino carbene.” Claim 25 again requires “Z and Z*” to form one of the recited carbenes, and claim 30 likewise requires “Z and Z*” to form its depicted carbene.
The claims therefore simultaneously incorporate a parent limitation under which Z* is absent when Z is a carbene and a dependent limitation under which Z and Z* together form the carbene. It is unclear whether Z* is absent, is a separate portion of the carbene, or represents a bonding/structural convention. The metes and bounds of claims 24, 25, and 30 therefore cannot be determined with reasonable certainty.
The specification itself states generally that “Z and Z* can together form a carbene” and identifies diaminocarbene and heteroaminocarbene species, whereas the generic claim-1 definition uses the distinct alternative “Z is a carbene and Z* is absent.” This confirms that the claim dependency, as presently drafted, combines different structural conventions without identifying which convention governs the dependent claims.
A potential clarifying amendment, if supported by the original disclosure and consistent with applicant's intent, would be to recite in claim 24 that “Z is a diaminocarbene or heteroaminocarbene and Z* is absent,” or alternatively to amend the parent structure so that the “Z and Z* together” convention is consistently used. No amendment adding new matter is suggested.
Claim 39 is rejected as indefinite because it is unclear whether a crown ether, aza-crown ether, thia-crown ether, cryptand, bis-chelating ligand, or tri-chelating ligand is itself intended to constitute M+, or instead is intended to complex or accompany a separate cation.
Claim 1 requires “M+” to be “a cation providing electronic balance.” Claim 39 states that M+ “comprises an alkali cation, an alkaline earth metal, or tetraalkylammonium, a crown ether, aza-crown ether, thia-crown ether, cryptand, bis-chelating ligand, tri-chelating ligand, or a combination thereof.”
The ordinary meaning of the recited crown ethers, cryptands, and chelating ligands does not establish that each listed material is itself the positively charged species required by claim 1. Consistently, the specification distinguishes the two concepts: it states that the “cationic component may further include a sequestration compound,” followed by crown ethers, aza-crown ethers, thia-crown ethers, cryptands, and chelating ligands.
It is therefore unclear whether claim 39 covers, for example, a crown ether alone as M+, an alkali-metal cation complexed by a crown ether, or both. Because these alternatives describe chemically different compositions and charge states, the claim does not distinctly define its scope.
If consistent with applicant's intended scope and the original disclosure, the distinction could be clarified by reciting, for example, an alkali-metal, alkaline-earth-metal, or tetraalkylammonium cation “optionally complexed with” or “in combination with” the recited sequestration ligand.
The following is a quotation of 35 U.S.C. 112(d):
(d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
The following is a quotation of pre-AIA 35 U.S.C. 112, fourth paragraph:
Subject to the following paragraph [i.e., the fifth paragraph of pre-AIA 35 U.S.C. 112], a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
Claims 8 & 24 rejected under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112, 4th paragraph, as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends.
Claim 8 purports to depend from claim 1 but specifies that R1a, R2a, and R3a are hydrogen. Claim 1 contains no R1a, R2a, or R3a variables. Those variables are introduced in claim 2. Accordingly, the limitation of claim 8 does not further restrict a parameter set forth in claim 1 and therefore does not establish the required dependent relationship.
If the intended subject matter is the R1a/R2a/R3a species of claim 2, claim 8 should depend from claim 2 rather than claim 1, subject to support and any other applicable requirements.
Claim 24 is rejected because, as presently written, it does not merely further limit claim 1 but conflicts with a limitation incorporated from claim 1.
A dependent claim necessarily incorporates all limitations of its parent. Claim 1 requires, in the relevant carbene alternative, “Z is a carbene and Z* is absent.” Claim 24 instead requires that “Z and Z* form a diaminocarbene or a heteroamino carbene.” Thus, claim 24 simultaneously incorporates the requirement that Z* is absent and purports to require Z* to participate with Z in forming the carbene.
Because the added limitation is inconsistent with, rather than a further limitation of, the incorporated parent limitation, claim 24 does not satisfy § 112(d). MPEP § 608.01(n) requires a dependent claim to contain every limitation of its parent and further restrict—not replace or contradict—the parent subject matter.
Applicant may cancel the claim(s), amend the claim(s) to place the claim(s) in proper dependent form, rewrite the claim(s) in independent form, or present a sufficient showing that the dependent claim(s) complies with the statutory requirements.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DEBORAH D CARR whose telephone number is (571)272-0637. The examiner can normally be reached Monday-Friday (10:30 am -6:30 pm).
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/DEBORAH D CARR/Primary Examiner, Art Unit 1691
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