Title of Invention

"A METHOD OF PRODUCTING CYANOALKYL TETRAALKYLPHOSPHORDIAMIDITE"

Abstract A method of producing cyanoalkyl tetraalkylphosphordiamidite comprising: a) reacting phosphorus trihalide with cyano-containing agent to form cyanoalkylphosphordihaildite; b) reacting the cyanoalkylphosphordihahdite with a dialkylamine to form cyanoalkyl tetraalkylphosphordiamidite and amine hydrohalide byproduct at least a portion of which is in the form of a precipitate; c) removing the amine hydrohalide precipitate by filtration to form a filtrate which may contain dissolved amine hydrohalide; and d) treating the filtrate with an a substance capable of removing any dissolved amine hydrohalide from the filtrate.
Full Text The present invention relates to a method of producing cyanoalkyl tetraalkylphosphordiamidite.
This application claims priority of U.S. Provisional Patent Application Serial No. 60/388,224 filed on June 13, 2002.
Field Of The Invention
The present invention is generally directed to the production of phosphordiamidite compounds which serve as key reagents for the preparation of, for example, antisense drugs. The present process facilitates the removal of undesirable amine hydrohalide compounds which are typically present in the reaction media and are carried to the final product. The elimination of such amine hydrohalide byproducts can improve the stability of the final product.
Background Of The Invention
Phosphordiamidite compounds such as cyanoalkyl
tetraalkylphosphordiamidite compounds are key reagents for the preparation of antisense drugs. Typically, such intermediate compounds are prepared by a two-step reaction in which a phosphorus trihalide is reacted with a 2-cyanoalkanol or 2-cyanoalkoxytnalkylsilane to form 2-cyanoalkylphosphordihalidite (NC-R1-O-P-X2 wherein R1 is an alkyl group preferably having from 1 to 6 carbon atoms and X is a haiide). The resulting phosphordihalidite compound is reacted with a dialkylamine to give the desired product (cyanoalkyi tetraalkylphosphordiamidite) having the following formula NC-R1-O-P[N(R2)]2 wherein each of R1 and R is an alkyl group, preferably having from 1 to 6 carbon atoms. An amine hydrohalide is produced as a byproduct. A major portion of the amine hydrohalide can be removed by filtration but there always remains a small amount of amine hydrohalide dissolved in the reaction media which can adversely affect the storage stability of the cyanoalkyi tetraalkylphosphordiamidite compounds. In particular, the presence of the amine hydrohalide renders the desired product unstable at ambient temperatures over extended periods of time.
It would therefore be a significant advance in the art to provide a method for the production of phosphordiamidites and particularly cyanoalkyi tetraalkylphosphordiamidites in which amine hydrohalide byproducts are removed from the reaction system to the extent that the desired product is stable at ambient temperatures for up to extended periods of time.
Summary Of The Invention
The present invention is generally directed to the production of phosphordiamidites and particularly cyanoalkyi tetraalkylphosphordiamidites in which amine hydrohalides are removed from the reaction media to the extent necessary to achieve a product with desired storage stability.
In accordance with one aspect of the present invention, there is provided a method of producing cyanoalkyi tetraalkylphosphordiamidites comprising:
a) reacting phosphorus trihalide with a cyano-containing reagent to form cyanoalkylphosphordihalidite;
b) reacting the cyanoalkylphosphordihalidite with a dialkylamine to form cyanoalkyi tetraalkylphosphordiamidite and an amine hydrohalide byproduct at least a portion of which is in the form of a precipitate;
c) removing the amine hydrohalide precipitate by filtration to form a filtrate which may contain dissolved amine hydrohalide; and
d) treating the filtrate with a substance capable of removing any dissolved amine hydrohalide from said filtrate.
Detailed Description Of The Invention
The present invention is generally directed to a method of producing cyanoalkyi tetraalkylphosphordiamidites as a reagent for the production of, for example, antisense drugs. The present invention is also directed to the production of a stable form of cyanoalkyi tetraalkylphosphordiamidites which are substantially free of amine hydrohalides.
In the first aspect of the present invention, phosphorus trihalide is reacted with a cyano-containing reagent to form cyanoalkylphosphordihalidite. The cyano-
containing reagent is preferably selected from the group consisting of a cyanoalkanol and a cyanoalkoxytnalkylsilane.
The alkanol group of the cyanoalkanol is preferably a C1-C6 alkanoi with ethanol being the most preferred alkanol. The alkoxy and alkyl groups of the cyanoalkoxytnalkylsilane preferably have 1-6 carbon atoms with ethoxy and methyl being the preferred alkoxy and alkyl groups, respectively.
With regard to the cyanoalkyiphosphordihalidite, the halides can include any halide (e.g. fluorine, chlorine and bromine). Chlorine is the preferred halide. The alkyl groups can be any alkyl group including straight or branch chained alkyl groups, preferably having from 1 to 6 carbon atoms. Ethyl is the preferred alkyl group.
The resulting cyanoalkyiphosphordihalidite is reacted with a dialkylamine. The preferred alkyl groups for the dialkylamine have from 1 to 6 carbon atoms. Isopropyl is the preferred alkyl group.
The above-mentioned reaction produces a hydrohalide byproduct which has to be neutralized for the reaction to go to completion. The hydrohalide byproduct can be neutralized by using an excess of a dialkylamine or a tertiary amine (e.g. thethylamine, pyridine and the like). The precipitated portion of the amine hydrohalide can be removed by filtration upon completion of the reaction. In accordance with the present invention, any residual amine hydrohalide may be
removed from the product through the use of an adsorbent alone or in the presence of a solvent, or through a reagent which renders the hydrohalide portion of the amine hydrohalide capable of being removed from the reaction system by filtration or the like. An example of such reagents are polymer-supported neutralizing agents such as, for example, triethylammonium methylpolystyrene carbonate and N, N-(diisopropyl)aminomethylpolystyrene. The removal of the amine hydrohalide significantly improves the stability of the product such as, for example, when stored at ambient temperatures over extended periods of time.
The adsorbents which may be used in the present invention are any adsorbents which preferentially absorb the amine hydrohalide from the reaction media. Examples of such adsorbents include, for example, alumina, silica gel, Florisil, Decalite and the like and combinations thereof.
The preferred solvents include tetrahydrofuran, diethyl ether, toluene, hexane and the like and mixtures thereof.
The respective amounts of the adsorbent and solvent is within the routine skill in the art and will be an amount sufficient to adsorb at least substantially all the dissolved residual amine hydrohalide byproduct.
The adsorbed amine hydrohalides may be easily removed together with the adsorbent from the reaction product by filtration to produce a product which is stable
at ambient temperatures for extended periods of time including and exceeding 120 days.
Examples
The following examples are illustrative of embodiments of the invention and are not intended to limit the invention as encompassed by the claims forming part of the application.
Example 1
Preparation and Stabilization of 2-Cyanoethyl-N,N,N,N'4etraisopropylphosphoro-diamidite (PDA)
2-(cyanoethoxy)dichlororphosphine (CDP) can be easily prepared by various processes described in the prior art. For example, the reaction of phosphorous trichloride (PCI3) with either 2-cyanoethanol or trimethylsilyloxypropionitrile (TMSOP) gives CDP in good yield. If desired, the product can be purified with careful vacuum distillation.
The CDP used in this example, and Example 2 was obtained by reacting PCI3 with TMSOP in a molar ratio of 2:1 in acetonitrile at 5°C. Upon completion of the reaction, the solvent and the excess PCI3 were removed by distillation. The crude
product was further purified by vacuum distillation, and gave CDP with greater than 98% purity.
A solution comprising 1.80 moles of freshly distilled 2-(cyanoethoxy)dichlorophosphine (CDP) (310 grams) in 2.9 Kg of tetrahydrofuran (THF) as solvent was stirred and cooled to -12 ± 2°C under a nitrogen blanket and then treated with 8.12 moles (820 grams) of diisopropylamine over a period of ninety minutes, maintaining a temperature of -10 ± 2°C. Stirring of the slurry was continued at ambient temperature for a period of 72 hours, at which time examination by 31P NMR showed no reaction intermediates remaining.
The slurry was filtered through a sintered glass filter to remove diisopropylamine hydrochloride (DIPA.HCI) solids. The clear filtrate was passed through a column of 350 grams of Brockmann activated neutral alumina that had been dried at 165°C at less than 1 Torr for 16 hours. The filtrate was concentrated on a rotary evaporator at a maximum bath temperature of 45°C. The distilled THF was used to rinse the DIPA.HCI and the alumina to collect additional product, which was combined with the first pass product and then concentrated until the vacuum reached 3 Torr. The yield of the pale yellow syrup was 485 grams (88.5% of theoretical) and the initial assay by 31P NMR was 99.7%. Table 1 shows a comparison of the stability of this material (A) vs. a sample prepared in the same manner, but without the alumina treatment (B).
Example 2
Preparation and Stabilization of 2-Cyanoethyl-N,N,N',N'-tetraisopropylphosphoro-diamidite (PDA).
In the same manner as detailed in Example 1, a reaction of 1.44 moles of CDP (248 grams) and 7.21 moles of DIPA (728 grams) in 3.0 Kg of toluene as the solvent showed, after 44 hours at ambient temperature, no evidence by 31P NMR that any reaction intermediates remained. The yield of very pale yellow syrup was 458 grams (103% of theoretical) and the initial assay by 31P NMR was 97.5%. Table 1 shows a comparison of the stability of this material (C) vs. a sample prepared in the same manner, but without the alumina treatment (D).
Table 1 (Table Removed)










We claim:
1. An improved method of producing cyanoalkyl tetraalkylphosphordiamidite for extended
stability at ambient temperature comprising:
a) reacting phosphorus trihalide with cyano-containing agent to form cyanoalkylphosphordihaildite;
b) reacting the cyanoalkylphosphordihalidite with a dialkylamine to form cyanoalkyl tetraalkylphosphordiamidite and amine hydrohalide byproduct at least a portion of which is in the form of a precipitate;
c) removing the amine hydrohalide precipitate by filtration to form a filtrate which may contain dissolved amine hydrohalide; and
d) treating the filtrate with an a substance capable of removing any dissolved amine hydrohalide from the filtrate.

2. The method as claimed in claim 1 wherein the substance capable of removing dissolved amine hydrohalide from the filtrate is selected from the group consisting of adsorbents and polymer-supported neutralizing agents.
3. The method as claimed in claim 2 wherein the adsorbents are selected from the group consisting of alumina, silica gel, Flotisil, Decalite and combinations thereof.
4. The method as claimed in claim 2 wherein the polymer-supported neutralizing agents are selected from the group consisting of triethylammonium methylpolystyrene carbonate and N, N-(diisopropyl)aminomethylpolystyrene.
5. The method as claimed in claim 1 optionally comprising removing the adsorbent containing the amine hydrohalide.
6. The method as claimed in claim 1 wherein the phosphorus trihalide is phosphorus trichloride.

7. The method as claimed in claim 1 wherein the cyano-containing reagent is selected from the group consisting of cyanoalkanol and cyanoalkoxytrialkylsilane.
8. The method as claimed in claim 7 wherein the alkanol group of the cyanoalkanol has from 1 to 6 carbon atoms.

9. The method as claimed in claim 8 wherein the alkanol group is ethanol.
10. The method as claimed in claim 7 wherein the alkoxy and alkyl groups of the cyanoalkoxytrialkylsilane have from 1 to 6 carbon atoms.
11. The method as claimed in claim 10 wherein the alkoxy group is ethoxy and the alkyl group is methyl.
12. The method as claimed in claim 1 wherein the alkyl group of the dialkylamine has from 1 to 6 carbon atoms.
13. The method as claimed in claim 1 optionally comprising neutralizing the hydrohalide by the addition of an excess of a neutralizing amine to precipitate at least a portion of the amine hydrohalide.
14. The method as claimed in claim 13 wherein the neutralizing amine is selected from the group consisting of dialkylamines and tertiary amines.
15. The method as claimed in claim 2 wherein the adsorbent is employed in the presence of a
solvent.
16. The method as claimed in claim 15 wherein the solvent is selected from the group
consisting of tetrahydrofuran, diethyl ether, toluene, hexane and mixtures thereof.
17. The method as claimed in claim 2 wherein the substance capable of removing dissolved
amine hydrohalide is a.polymer-supported neutralizing agent.
18. The method as claimed in claim 17 wherein the polymer-supported neutralizing agent is
selected from the group consisting of triethylammonium methylpolystyrene carbonate
and N,N-(diisopropyl)aminomethylpolystyrene.
19. A product produced by the process as claimed in claim 1.


Documents:

3812-delnp-2004-Abstract-(03-01-2011).pdf

3812-delnp-2004-abstract.pdf

3812-delnp-2004-assignment.pdf

3812-DELNP-2004-Claims-(01-06-2011).pdf

3812-delnp-2004-Claims-(03-01-2011).pdf

3812-DELNP-2004-Claims-(31-05-2011).pdf

3812-delnp-2004-claims.pdf

3812-DELNP-2004-Correspondence Others-(01-06-2011).pdf

3812-DELNP-2004-Correspondence Others-(31-05-2011).pdf

3812-delnp-2004-Correspondence-Others-(03-01-2011).pdf

3812-delnp-2004-correspondence-others.pdf

3812-delnp-2004-Description (Complete)-(03-01-2011).pdf

3812-delnp-2004-description (complete).pdf

3812-delnp-2004-Form-1-(03-01-2011).pdf

3812-delnp-2004-form-1.pdf

3812-delnp-2004-form-18.pdf

3812-delnp-2004-Form-2-(03-01-2011).pdf

3812-delnp-2004-form-2.pdf

3812-DELNP-2004-Form-3-(01-06-2011).pdf

3812-delnp-2004-Form-3-(03-01-2011).pdf

3812-DELNP-2004-Form-3-(31-05-2011).pdf

3812-delnp-2004-form-3.pdf

3812-delnp-2004-form-5.pdf

3812-delnp-2004-GPA-(03-01-2011).pdf

3812-delnp-2004-gpa.pdf

3812-delnp-2004-pct-101.pdf

3812-delnp-2004-pct-210.pdf

3812-delnp-2004-pct-304.pdf

3812-delnp-2004-pct-402.pdf

3812-delnp-2004-pct-408.pdf

3812-delnp-2004-pct-409.pdf

3812-delnp-2004-pct-416.pdf

3812-delnp-2004-Petition 137-(03-01-2011).pdf


Patent Number 248479
Indian Patent Application Number 3812/DELNP/2004
PG Journal Number 29/2011
Publication Date 22-Jul-2011
Grant Date 18-Jul-2011
Date of Filing 01-Dec-2004
Name of Patentee RHODIA INC.
Applicant Address CN 7500, 259 PROSPECT PLAINS ROAD, CRANBURY, NJ 08512, UNITED STATES OF AMERICA
Inventors:
# Inventor's Name Inventor's Address
1 SHIMING WO 3006 VISTA COURT, SUMMERVILLE, SC 29485, USA
2 BING WANG 305 THOMASTON AVENUE, SUMMERVILLE, SC 29485, USA
3 DWIGHT SHAMBLEE 8534 RANDALL COURT, NORTH CHARLESTON, SC 29420, USA,
PCT International Classification Number C07F 9/06
PCT International Application Number PCT/US2003/17982
PCT International Filing date 2003-06-09
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/388,224 2002-06-13 U.S.A.