Prosecution Insights
Last updated: April 19, 2026
Application No. 18/219,447

PROCESS FOR PREPARING PHOSPHONATE ESTERS

Final Rejection §102§103
Filed
Jul 07, 2023
Examiner
CHAO, ALLEN
Art Unit
1622
Tech Center
1600 — Biotechnology & Organic Chemistry
Assignee
Entegris Inc.
OA Round
2 (Final)
Grant Probability
Favorable
3-4
OA Rounds
3y 2m
To Grant

Examiner Intelligence

Grants only 0% of cases
0%
Career Allow Rate
0 granted / 0 resolved
-60.0% vs TC avg
Minimal +0% lift
Without
With
+0.0%
Interview Lift
resolved cases with interview
Typical timeline
3y 2m
Avg Prosecution
18 currently pending
Career history
18
Total Applications
across all art units

Statute-Specific Performance

§103
43.2%
+3.2% vs TC avg
§102
25.0%
-15.0% vs TC avg
§112
20.5%
-19.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 0 resolved cases

Office Action

§102 §103
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 . DETAILED ACTION This office action is in reply to the Applicant’s Arguments and Amendment filed 04 March 2026. Claims 1 and 8 are amended. Claims 6-7 and 9-18 are canceled. Currently, claims 1-5 and 8 are pending. Information Disclosure Statement The information disclosure statement (IDS) submitted on 25 February 2026 was filed after the mailing date of the application on 07 July 2023. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner. REJECTIONS – MAINTAINED & NEW 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. (a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention. (New) Claims 1-2 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Hutchinson et al. (Synthesis of alkylated methylene bisphosphonates via organothallium intermediates, J. Organometallic Chem. 1985, 291, 145-151; entered into the IDS on 22 December 2023). In pursuit of halogenated methylene bis-phosphonic acids, Hutchinson discloses a method to obtain medronic acid through the hydrolysis of tetraisopropyl esters of methylene bis-phosphonic acids through the use of bromotrimethylsilane, added under dry nitrogen, stirred for ≥20 hours, lyophilized, then dissolved in aqueous methanol which was removed in vacuo. This last procedure was repeated four times, then the residues dissolved in water and isolated via ion exchange chromatography (pg. 151, section – viii). This reaction is best illustrated by Scifinder© as the reference itself provides little in the way of visual representation: PNG media_image1.png 296 1065 media_image1.png Greyscale As the claim does not specify exact reaction conditions, Hutchinson reads upon the claim where medronic acid tetraisopropyl ester, contacted with trimethylsilyl bromide to form a mixture, and treating the mixture with a liquid comprising water, thereby forming medronic acid. As such, Hutchinson anticipates claim 1. (New) With regards to the limitations of claim 2, wherein the compound of the formula (A) is reacted with trimethylsilyl bromide or trimethylsilyl iodide, are met as Hutchinson uses trimethylsilyl bromide to deprotect medronic acid tetraisopropyl ester. 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. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or non-obviousness. (New) Claims 3-4 are rejected under 35 U.S.C. 103 as being unpatentable over Hutchinson et al. (Synthesis of alkylated methylene bisphosphonates via organothallium intermediates, J. Organometallic Chem. 1985, 291, 145-151) in view of Vaghefi et al. (Synthesis of certain nucleoside methylenediphosphonate sugars as potential inhibitors of glycosyltransferases, J. Med. Chem. 1987, 30, 8, 1391-1399). Hutchinson discloses a method of deprotecting medronic acid tetraisopropyl ester using trimethylsilyl bromide followed by hydrolysis with aqueous methanol. Hutchinson does not, however, teach where the compound of the formula (A) is reacted with trimethylsilyl chloride and an alkali metal iodide or bromide. Vaghefi addresses this by teaching deprotection of medronic acid diisopropyl ester diphenyl ester 8 using trimethylsilyl chloride with sodium iodide to yield medronic acid diphenyl ester 5: PNG media_image2.png 367 367 media_image2.png Greyscale As such, it would have been prima facie obvious, to a person of ordinary skill in the art, before the effective filing date, to consider the use of trimethylsilyl chloride with sodium iodide to perform deprotection of isopropyl phosphonic acid esters, in light of the teachings of Veghefi, and apply these same conditions to the deprotection of medronic acid tetraisopropyl ester. Regarding the limitation of claim 4, wherein an alkali metal iodide is utilized and is sodium iodide, is met as Veghefi teaches the use of sodium iodide with trimethylsilyl chloride in phosphonic acid ester deprotection. (New) Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Hutchinson and Veghefi as applied to claims 3-4 above, and further in view of Erion et al. (Thyroid hormone receptor agonist and use thereof, WO 2017/184811 A1, 2017). Hutchinson discloses a method of deprotecting medronic acid tetraisopropyl ester using trimethylsilyl bromide followed by hydrolysis with aqueous methanol. Veghefi further expands this by teaching deprotection using trimethylsilyl chloride and sodium iodide. They do not, however, teach where the alkali metal iodide utilized is potassium iodide. Erion fixes this shortcoming by teaching the use of potassium iodide with trimethylsilyl chloride in the deprotection of diisopropyl phosphonic acid ester 1G to give the resulting phosphonic acid 1I (pg. 40 – scheme 1, para. 0134): PNG media_image3.png 115 428 media_image3.png Greyscale As such, it would have been prima facie obvious, to a person of ordinary skill in the art, before the effective filing date, to consider the use of potassium iodide as an alternative to sodium iodide along with trimethylsilyl chloride to perform deprotection of isopropyl phosphonic acid esters, in light of the teachings of Erion, and apply this condition to the deprotection of medronic acid tetraisopropyl ester. (New) Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Hutchinson et al. (Synthesis of alkylated methylene bisphosphonates via organothallium intermediates, J. Organometallic Chem. 1985, 291, 145-151) in view of Chiminazzo et al. (Challenging synthesis of bisphosphonate derivatives with reduced steric hindrance, Tet. Lett. 2021, 70, 153012; entered in the IDS 22 December 2023). Hutchinson discloses a method of deprotecting medronic acid tetraisopropyl ester using trimethylsilyl bromide followed by hydrolysis with aqueous methanol. Hutchinson does not, however, teach post alkylation by further comprising reacting the medronic acid with an alkylating compound of the formula HC(OR)3, wherein R is a methyl. Chiminazzo rectifies this deficiency by teaching alkylation, using trimethyl orthoformate, of bis-phosphonic acid 8 to give medronic acid tetramethyl ester 5 under refluxing conditions yielding 71% (pg. 2, scheme 2). Once again, this is best illustrated by Scifinder© as scheme 2 in the reference includes more elements than is required and does not fit well into this office action: PNG media_image4.png 276 1045 media_image4.png Greyscale As such, it would have been prima facie obvious, to a person of ordinary skill in the art, before the effective filing date, to apply the same experimental conditions as taught by Chiminazzo to medronic acid to obtain medronic acid tetramethyl ester using trimethyl orthoformate. Summary Claim 1 is rejected under 35 U.S.C. 102(a)(1). Claims 2-5 and 8 are rejected under 35 U.S.C. 103. Conclusion No claims are allowed. Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to Allen Chao whose telephone number is (571)272-7001. The examiner can normally be reached Monday - Friday 0700-1300. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, James H Alstrum-Acevedo can be reached at 571-272-5548. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /ALLEN CHAO/Examiner, Art Unit 1622 /JAMES H ALSTRUM-ACEVEDO/Supervisory Patent Examiner, Art Unit 1622
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Prosecution Timeline

Jul 07, 2023
Application Filed
Nov 03, 2025
Non-Final Rejection — §102, §103
Mar 04, 2026
Response Filed
Mar 25, 2026
Final Rejection — §102, §103 (current)

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Prosecution Projections

3-4
Expected OA Rounds
Grant Probability
3y 2m
Median Time to Grant
Moderate
PTA Risk
Based on 0 resolved cases by this examiner. Grant probability derived from career allow rate.

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