FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule l3)
1. TITLE OF THE INVENTION:
PROCESS FOR PREPARATION OF OCTREOTIDE OR SALT OR DERIVATIVE OR INTERMEDIATE THEREOF
2. APPLICANT (S)
(a) NAME: WOCKHARDT LTD.
(b) NATIONALITY: INDIAN
(c) ADDRESS: Wockhardt Towers, Bandra-Kurla Complex, Bandra (East),
Mumbai-400 051.
3. PREAMBLE TO THE DESCRIPTION
The present invention relates to an efficient process for the preparation of octreotide or salt or derivative or intermediate thereof.
The following specification particularly describes the invention and the manner
in which it is to be performed.
4. DESCRIPTION
The present invention relates to an efficient process for the preparation of octreotide or salt or derivative or intermediate thereof.
Octreotide is an octapeptide. It is a long-acting octapeptide with pharmacologic properties mimicking those of the natural hormone somatostatin. Octreotide is indicated to reduce blood levels of growth hormone and IGF-I in acromegaly patients. It is also indicated for the symptomatic treatment of patients with metastatic carcinoid tumors and Vasoactive Intestinal Peptide Tumors (VIPomas)
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FORMULA 1
US Patent No 4,395,403 (the '403 Patent) and European Patent No EP 29,579 (the '579 Patent) discloses solution synthesis for the preparation of octreotide.
Several solid phase synthesis procedures have been subsequently described viz. European Patent No EP 953,577 and U.S. Pat. No 5,889,146 and in various research publications. Mergler et al (Proceedings of the 12.sup.th American Peptide Symposium) have used aminomethyl resin and Fmoc-butyl protection scheme for synthesis of octreotide. Alsina et al. Tetrahedron Letters, 38, 883, 1997) have used an active carbonate resin and Boc-Bzl protection scheme, necessitating the use of hydrogen fluoride/anisole for final deprotection. Edwards et al (J. Med. Chem., 37, 3749, 1994)) have described another synthesis using Fmoc-butyl protection and HMP resin, and Berta et al (EP 953,577) described a synthesis using 2-chlorotrityl-type resin and Fmoc-butyl protection scheme.
All the solid phase synthesis procedures described are not suitable for commercial manufacture of octreotide because they use costly resins and costly Fmoc-butyl protected amino acids in 2 to 4 times excess at every step. Some synthesis procedures use destructive and hazardous reagents for final deprotection.
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The present inventors now found out an efficient process for the preparation of octreotide or salt or derivative thereof which is optimized at every step and has the advantages of simple technique, reduced process time, low ratio of reactants, lowered cost, enhanced yield and purity, easy purification and applicability for large-scale production.
In one aspect of the invention there is provided a process for preparation of Ri-(D)Phe-Cys(Acm)-Phe-OH, wherein Ri is amino or suitable amino protecting group used in peptide chemistry, wherein the said process comprises of
a) hydrolyzing Ri-(D)Phe-Cys(Acm)-Phe-OMe in presence of methanol and lithium hydroxide,
b) acidifying the reaction mass after completion of hydrolysis,
c) isolating Rr(D)Phe-Cys(Acm)-Phe-OH from the reaction mass thereof.
In yet another aspect of the invention there is provided a process for preparation ^of Ri-(D)Phe-Cys(Acm)-Phe-OH, wherein Ri is amino or suitable amino protecting group used in peptide chemistry, wherein the said process comprises of
a) hydrolyzing Ri-(D)Phe-Cys(Acm)-Phe-OMe in presence of a suitable organic solvent by maintaining a pH of about 9.0 to 10 throughout the reaction time,
b) acidifying the reaction mass after completion of hydrolysis,
c) isolating Ri-(D)Phe-Cys(Acm)-Phe-OH from the reaction mass thereof.
Ri-(D)Phe-Cys(Acm)-Phe-OMe was prepared by the procedure which is well known to those skilled in the art. Prior art mentions use of sodium hydroxide for hydrolysis of Ri-(D)Phe-Cys(Acm)-Phe-OH which gives racemization of up to 35% resulting in reduction of desired product yield. When Potassium hydroxide was used instead of sodium hydroxide racemization was reduced only up to 25%. The present inventors now used lithium hydroxide and it was observed that racemization was reduced up to 15% thus resulting in increase in desired product
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yield. It was further observed that when hydrolysis of Ri-(D)Phe-Cys(Acm)-Phe-OMe was carried out at a pH of about 9.0 to 10 throughout the reaction time, this pH optimizes the yield of product and quality. This can be simply achieved by adding small quantities of base at regular intervals once the pH of the reaction mass starts to lower below 9. This reduces the presence of excess alkali required for racemization and improves yield and quality of the product.
The intermediates thus obtained as part of this invention can be converted to octreotide or salt thereof by processes known in the art.
While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.
Example 1 Preparation of Boc-(D)-Phe-Cys(ACM)-Phe-OH
Lithium hydroxide solution (140 ml, 1M) was added drop wise to the solution of Rr(D)Phe-Cys(Acm)-Phe-OMe (112 g) in methanol (2500 ml) at 20- 25 °C. The solution was stirred at 30°C till completion of reaction as monitored by HPLC. The PH was brought to 2-3 by addition of Hydrochloric acid (584 ml, 1N) at 5-10°C. The solution was concentrated under vacuum. The concentrate was saturated with solid sodium chloride and diluted with ethyl acetate (1000 ml). Ethyl acetate layer was separated and aqueous layer was extracted with ethyl acetate (1000 ml). Combined extracts were evaporated under vacuum and to the residue was added ether (1000 ml). The separated solids were filtered and dried to get the title compound. Yield = 78g
Calculated Mass - 586 Obtained mass - 587
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WE CLAIM:
1. A process for preparation of Ri-(D)Phe-Cys(Acm)-Phe-OH, wherein Ri is
amino or suitable amino protecting group used in peptide chemistry, wherein the
said process comprises of
a) hydrolyzing Ri-(D)Phe-Cys(Acm)-Phe-OMe in presence of methanol and lithium hydroxide,
b) acidifying the reaction mass after completion of hydrolysis,
c) isolating Ri-(D)Phe-Cys(Acm)-Phe-OH from the reaction mass thereof.
2. A process for preparation of Ri-(D)Phe-Cys(Acm)-Phe-OH, wherein Ri is
amino or suitable amino protecting group used in peptide chemistry, wherein the
said process comprises of
a) hydrolyzing Ri-(D)Phe-Cys(Acm)-Phe-OMe in presence of a suitable organic solvent by maintaining a pH of about 9.0 to 10 throughout the reaction time,
b) acidifying the reaction mass after completion of hydrolysis,
c) isolating Ri-(D)Phe-Cys(Acm)-Phe-OH from the reaction mass thereof.

3. A process according to claim 1 or 2 wherein isolation comprises of acidification of reaction mass and extraction in a suitable organic solvent.
4. A process according to claim 3 wherein the organic extracts are concentrated and residue is treated with ether.
5. A process according to claim 2 wherein the pH is adjusted using a base.
6. A process according to claim 5 wherein the base is hydroxide, carbonate or bicarbonate of alkali or alkali earth metal compound.
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7. A process for preparation of octreotide or salt thereof comprising process according to claims 1 or 2.
Dated this 28 TH day of March, 2006

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