WO2014125499A1

WO2014125499A1 - Improved and commercially viable process for the preparation of high pure plerixafor base

Info

Publication number: WO2014125499A1
Application number: PCT/IN2013/000093
Authority: WO
Inventors: Janaki Rama Rao Ravi; Sathish THUMATI; Naresh GHANTA; Pulla Reddy Muddasani; Kali Satya Bhujanga Rao Adibhatla; Venkaiah Chowdary Nannapaneni
Original assignee: Natco Pharma Limited
Priority date: 2013-02-13
Filing date: 2013-02-13
Publication date: 2014-08-21

Abstract

The present invention relates to an improved and commercially viable process for the preparation of ≥ 99.8% pure plerixafor base (1) by HPLC. The process of the present invention involves simple crystallization techniques to isolate the compounds at each step without employing the laborious column chromatography technique. The solid state characteristics of plerixafor base also discussed by PXRD, DSC and I.R spectroscopy.

Description

IMPROVED AND COMMERCIALLY VIABLE PROCESS FOR THE PREPARATION OF HIGH PURE PLERIXAFOR BASE

FIELD OF THE INVENTION

The present invention relates to an improved process for the preparation of high plerixafor base.

BACKGROUND OF THE INVENTION

Plerixafor base (1) is an anticancer agent used for mobilization of hematopoietic stem cells from the bone marrow to the blood stream as peripheral blood stem cells. Chemical name of plerixafor is l, -[l,4-phenylenebis(methylene)bis[l,4,8,l 1- tetraazacyclotetradecane] and the structural formula is depicted below.

1

Plerixafor drug was first developed by Anormed which was subsequently bought by Genzyme and brought into the market. The brand name of plerixafor is Mozobil* which i s in the form of injection of strength 24mg/l .2mL.

In PCT application WO 93/12096, and its corresponding US patent 5583 1 31 authors disclosed different aromatic linked polyamine macrocyclic compounds with their anti- HIV activity along with the plerixafor. Synthesis of tetrafluoro derivative of plerixafor has been illustrated as an example in this application. Synthetic scheme is depicted below (Scheme- 1).

8 HBr 2H₂0

7

Scheme-1

Peril uoroterephthalic acid (2) was reduced to 2,3,5,6-tetrafluoro-p-xylene-a,a^*-diol (3) in the presence of BH₃:THF complex at room temperature, yield of the product 86%. Compound of formula (3) was protected with methane sulfonyl chloride in the presence of triethyl amine to yield 2,3,5,6-tetrafluoroTp-xylene-a,cc'-diol dimesylate (4) in 72% yield. The resulting 2,3,5,6-tetrafluoro-p-xylene-a,a'-diol dimesylate (4) was coupled with tris-(p-toluenesulfonyl)-l,4,8,l l-tetraazacyclotetradecane (5) in the presence of potassium carbonate in acetonitrile at reflux temperature to give 1, -[2,3,5,6- Tetrafluoro-l,4-phenylene-bis-(methylene)]-bis-tris-(p-toluenesulfonyl)-l,4,8,l l- tetraazacyclotetradecane (6), this compound was purified by column chromatography and yield was not given. Finally compound (6) was subjected to hydrolysis by acetic acid and aq. HBr at 100°C to afford l, -[2,3,5,6-Tetrafluoro-l,4-phenylenebis-(methylene)]-bis- 1,4,8,11-tetraazacyclotetradecane octahydrobromide dihydrate (7) in 40% yield.

Main drawbacks of the above process are lack of product quality information and involvement of column chromatography at step-3.

In PCT application WO 00/28987, authors described a process for the preparation of plerixafor octahydrochloride dihydrate employing cyclam (8) as starting material. S nthetic scheme is depicted below (scheme-2).

Scheme-2

Cyclam (8) was reacted with p-toluene sulfonyl chloride (9) in the presence of triethyl amine in chloroform to get tris-(p-toluenesulfonyl)- 1,4, 8,11-tetraazacyclotetradecane (5). This compound (5) was obtained in 33% yield after trituration with methanol. Methanol from filtrate was distilled off to get a residue which was reprocessed as above with chloroform, triethylamine and p-toluene sulfonyl chloride to get another 13% yield. The resulting compound (5) was reacted with a, a'-dibromo-p-xylene (10) in the presence of potassium carbonate in acetonitrile at reflux temperature to yield 1,1'-[1,4- phenylenebis(methylene)]-bis[4,8, 11 -tris-(p-toluenesulfonyl)- 1 ,4,8, 11 - tetraazacyclotetradecane (11) 89% yield. Tosyl moieties of compound (1 1) were deprotected upon treating with mixture of acetic acid and 48% aq. HBr at 100°C for 48h to yield plerixafor 8 HBr 2H₂0 ( 12) in 48% yield.

The above plerixafor 8HBr 2H₂0 (12) was basified and then immediately converted into plerixafor 8HC1 2H₂0 (13) in 38% yield upon addition of cone. HC1 to the ethanolic solution of residual plerixafor base.

Main disadvantages of above process are yields were low at every step and purity was not mentioned. The important compound plerixafor base was not isolated in pure form, the crude was takeri to HC1 salt formation.

In another instance, WO02/26721A1, authors disclosed a process for the preparation of plerixafor base using ethyl trifluoroacetate as protecting reagent instead of p-toluene sulfon l chloride. Scheme is shown below (Scheme-3).

Scheme-3

Cyclam (8) was reacted with ethyl trifluoroacetate in the presence of triethylamine in methanol to give tris trifluoroacetyl cyclam (14). Compound was isolated by column chromatography technique, yield of compound 92.5%. Purity of compound was not mentioned. Compound (14) was coupled with a, a'-dichloro-p-xylene (15) in the presence of potassium carbonate and potassium iodide in acetonitrile at reflux temperature to get compound (16) in 85% yield. Here also compound purity not given. Deprotection of trifluoro acetyl group of compound (16) achieved by treatment with potassium carbonate in methanol to afford plerixafor base (1) in 86% yield. Compound was isolated from toluene and purity was not given. Yields were good in this process but purity of compound was not mentioned at any stage.

Jean Dessolin et al described a process in J. Med. Chem. 1999, 42, 229-241 for the preparation of plerixafor hexahydrochloride (19) using cyclam (8) and di-tert-butyl dicarbonate as the protecting group. Reaction path way is given below (Scheme-4).

19

Scheme-4

Cyclam (8) was protected with di-tert-butyl dicarbonate in methylene chloride to give tris-Boc protected cyclam (17) in 24% yield, compound was isolated by column chromatography. Compound (17) was reacted with α,α'-dibromoxylene (10) in the presence of potassium carbonate in acetonitrile to yield Ι,Γ-xylyl-bis [4,8,1 l-tris(tert- butoxycarbonyl)-l,4,8,l l-tetraazacyclotetradecane] (18). The resulting compound was subjected to treating with dry HC1 gas in diethyl ether to give plerixafor hexahydrochloride (19). The main drawbacks of the process are involvement of column chromatography for compounds isolation in the first two steps and yield is very low. Another disadvantage of the process is that process has been evaluated on gram and milligram scale. Preparation of the main compound plerixafor base (1 ) was not disclosed.

In another publication, Synthetic Communications, 28 (15), 2903-2906 (1998), authors disclosed one pot process for the preparation plerixafor octahydrochloride. The process involves usage of phosphorus oxy chloride as reagent to form phosphoric triamide (20) with cyclam then the complex was taken to subsequent steps to yield plerixafor octahydrochloride (13). Reaction pathway is depicted below (Scheme-5)

1. ACN (or DMF), Na₂C0₃ reflux

8 20 13

Scheme-5

No process was given for isolation of plerixafor base (1) which is an active drug substance of pharmaceutical compositions.

Michal Achmatowicz and Louis S. Hegedus (J. Org. Chem., 2003, 68 (16), 6435-6436) described novel process for the preparation of plerixafor octahydrochloride (13). According to the process, methyl acrylate (21) was reacted with excess amount of ethylene diamine (22) through Michael addition to form triamine amide (23) as oil. The resulting triamine amide (23) was condensed with dimethyl malonate (24) to yield trioxocyclam (25) and was coupled with α,α'-dibromoxylene (10) in the presence of N,N- diisopropyl ethyl amine to get p-xylene-linked-bis-trioxocyclam (26). Finally p-xylene- linked-bis-trioxocyclam (26) was reduced in the presence of borane:dimethylsulfide complex followed by treating with methanolic HCI to afford plerixafor octahydrochloride trihydrate (13) as white solid. Synthetic scheme is depicted below (Scheme-6).

25 26 13 Scheme-6

Disadvantages of above process are not mentioning the purity of compounds at any step. Purification of triamine amide (23) is difficult as it is highly viscous oil and could not be distilled off. Removal of excess ethylene diamine present in triamine amide (23) is also difficult. Isolation of trioxocyclam (25) involves column chromatography which is time consuming and limits the batch size, yield is also very low. The final step of the process which involves conversion of p-xylene-linked-bis-trioxocyclam (26) to plerixafor octahydrochloride trihydrate (13) is laborious. The nasty reagent B¾: DMS complex has been employed as reducing agent for the conversion of p-xylene-linked-bis-trioxocyclam (26) to plerixafor. Decomposition of this reagent is difficult and could not be recommending for scale-up batches. Purification of plerixafor base (1) is not given in the process; the crude compound was directly taken to octahydrochloride salt formation.

SUMMARY OF THE INVENTION

According to the European Medicines Agency (EMEA) report active ingredient in Mozobil is plerixafor free base. Mozobil is a sterile, preservative-free, clear, colourless to pale yellow, isotonic, solution for subcutaneous injection containing plerixafor as the active substance in a concentration of 20 mg/ml. In all the above mentioned prior art references no process for preparation of pharmaceutically acceptable grade plerixafor is described. Thus there is a need to develop a process for the preparation of high purity plerixafor base with all the identified or unidentified impurities in pharmaceutically acceptable level (<0.1%). Keeping in view of the difficulties in commercialization of the above-mentioned processes for the preparation of high purity (>99.8%) plerixafor, we aimed to develop a simple and economical process for commercial production of plerixafor with >99.8% purity. We observed that a promising approach for a process for the preparation of high purity (>99.8%) plerixafor would be to (a) avoid the column chromatography technique to purify the intermediates used in the process; (b) usage of simple crystallization techniques to purify the intermediates used in the process; (c) and purify technical grade plerixafor into pharmaceutical grade by employing crystallization techniques.

Accordingly, the main objective of the present invention is to provide an improved process for the preparation of plerixafor, which is commercially applicable.

Another objective of the present invention is to provide an improved process for the preparation of plerixafor avoiding the column chromatography technique to purify the intermediates used in the process.

Still another objective of the present invention is to employ simple crystallization techniques to purify the intermediate compounds at each step.

DESCRIPTION OF THE INVENTION

The present invention has been developed based on our finding that by controlling the quality of intermediates used in the synthesis one would get good quality plerixafor. Purification of this good quality plerixafor into pharmaceutically acceptable grade is possible by simple crystallization techniques.

Accordingly, process of the present invention provides an improved process for the preparation of high purity (>99.8%) plerixafor of formula 1 ,

which comprises,

(i) reaction of cyclam of formula (8

8

with p-toluene sulfonyl chloride of formula (9)

in the presence of a base in an organic solvent at a temperature to get crude tris-(p-toluenesulfonyl)- 1 ,4,8, 11 -tetraazacyclotetradecane of formula (5)

purification of crude tris-(p-toluenesulfonyl)- 1,4,8,11- tetraazacyclotetradecane of formula (5) by trituration and/or crystallization from an organic solvent to get pure tris-(p-toluenesulfonyl)-l, 4,8,11- tetraazacyclotetradecane of formula (5)

reaction of pure compound of formula (5) with a, a'-dibromo-p-xylene of formula (10)

10

in the presence of a base in an organic solvent at a temperature to get 1,1' [1 ,4-phenylenebis(methylene)]-bis[4,8,l 1 -tris-(p-toluenesulfonyl)-l ,4,8, 11 - tetraazacyclotetradecane of formula (11)

(iv) purification of compound of formula (11) by recrystallization from a suitable solvent.

(v) reaction of compound of formula (11) with a strong acid at elevated temperature to get plerixafor acid addition salt of formula (12)

12

(vi) reaction of compound of formula (12) with a base in the presence of an aqueous solvent medium to get pure plerixafor base of formula (1)

(vii) recrystallization of above obtained pure plerixafor base from a suitable solvent to get pharmaceutically acceptable grade high purity (>99.8%) plerixafor base as a crystalline solid.

In a preferred embodiment of the present invention organic solvent used in step (i) can be selected from chlorinated hydrocarbons such as dichloromethane, chloroform, ethylene chloride, etc. or aromatic hydrocarbons like toluene, xylene, etc. Preferable solvent medium is chlorinated solvents like dichloromethane and chloroform, more preferable solvent is dichloromethane. Reaction temperature in step (i) can be in the range of 20- 100°C, preferably 20-45°C. Mole equivalents of p-toluenesulfonyl chloride used in step (i) can be in the range of 1.5 to 2.5, preferably 2.0 mole equivalents. The base used in step (i) can be selected from organic bases such as tertiary alkyl amines such as triethylamine, tributylamine, diisopropylethylamine, hetero aromatic amines such as pyridine, lutidine, collidine, etc., preferably tertiary alkyl amines more preferably triethylamine. Mole equivalents of base used in step (i) can be in the range of 2.0-3.0, preferably 2.5 mole equivalents.

Solvent used for trituration of crude compound of formula (5) in step (ii) is selected from Q-C4 alkanols, preferably methanol or isopropyl alcohol, more preferably methanol. The suitable solvent used in step (ii) for recrystallization of compound of formula (5) is selected from Q-Q alkanols, or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate, or aliphatic ketones such as acetone, methyl t-butyl ketone, methyl ethyl ketone, or aliphatic halo hydrocarbons like dichloromethane, chloroform, ethylene chloride, etc. or aliphatic hydrocarbons selected from C₅-C₇ or aromatic hydrocarbons such as toluene, xylene or mixtures thereof. Preferable solvent system for recrystallization is a combination of dichloromethane and hexane in the ratio of 1 : 1 The base used in step (iii) is selected from inorganic bases such as alkali metal carbonates such as sodium or potassium carbonate or alkaline earth metal carbonates such as calcium carbonate, barium carbonate or organic bases such as tertiary alkyl amines like triethylamine, tributylamine, diisopropylethylamine, hetero aromatic amines such as pyridine, lutidine, collidine* etc., preferably alkali metal carbonates, more preferably potassium carbonate.

Suitable solvent medium used in step (iii) is selected from polar aprotic solvents such as acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide and aromatic hydrocarbons like toluene, xylene, etc., preferably acetonitrile or Ν,Ν-dimethylformamide, more preferably Ν,Ν-dimethylformamide. Mole equivalents of compound of formula (5) in step (iii) to compound of formula (10) are 1.2-2.5, preferably 1.5-1.8. Temperature of the reaction in step (iii) is in the range of 0 to 150°C, preferably, 40-85°C, more preferably 75-85°C. Solvent used in purification of compound of formula (1 1) in step (iv) is selected from Ci- C₄ alkanols, or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate or aliphatic ketones from acetone, methyl t-butyl ketone, methyl ethyl ketone, or aliphatic halo hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, ethylene dichloride, etc. or C₅-C aliphatic hydrocarbons or aromatic hydrocarbons such as benzene, toluene, xylene or aliphatic ethers like diethyl ether, methyl ethyl ether, diisopropyl ether, tetrahydrofuran or mixtures thereof. Preferable solvent is dichloromethane, chloroform, carbon tetrachloride, ethylene chloride, more preferable solvent is dichloromethane. > Suitable acid used in the deprotection of tosyl group of compound of formula (1 1) in step (v) is the combination of aq. hydrobromic acid and acetic acid. Solvent used in purification of compound of formula (12) in step (v) is selected from aliphatic lower alcohols C1-C4, or aliphatic ketones such as acetone, methyl-butyl ketone, methyl ethyl ketone, etc or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate, etc or aliphatic halo hydrocarbons selected from dichloromethane, chloroform, carbon tetrachloride, ethylene chloride etc. or C5-C7 aliphatic hydrocarbons or aromatic hydrocarbons selected from benzene, toluene, xylene, etc or aliphatic ethers like diethyl ether, methyl ethyl ether, diisopropyl ether, tetrahydrofuran or mixtures thereof. Preferable solvent is aliphatic lower alcohols C1-C4, more preferably methanol.

Appropriate base used in liberation of plerixafor base of formula (1) in step (vi) is selected from alkali metal or alkaline earth metal carbonates, hydroxides, or aq. ammonia solution. Preferably alkali metal hydroxides, more preferably sodium hydroxide. Suitable pH of the reaction mass to be maintained in step (vi) is ranging from 9-14, preferably 12- 14 more preferably 13-14. Suitable solvent to extract the plerixafor base in step (vi) is selecting from aliphatic halo hydrocarbons like dichloromethane, chloroform, carbon tetrachloride, ethylene chloride etc or aromatic hydrocarbons such as toluene, xylene or aliphatic esters like ethyl acetate, n-propyl acetate, n-butyl acetate etc. preferably aromatic hydrocarbons, more preferably toluene. The temperature in extraction of the liberated plerixafor base in step (vi) is ranging from 25-100°C, preferably 50-80°C, more preferably 55-70°C.

Suitable solvent used in purification of plerixafor base of formula (1) in step (vi) is selected from aliphatic ketones such as acetone, methyl t-butyl ketone, methyl ethyl ketone, etc or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate, etc or C₅-C₇ aliphatic hydrocarbons or aromatic hydrocarbons like toluene, xylene or aliphatic ethers like diethyl ether, methyl ethyl ether, diisopropyl ether, tetrahydrofuran or mixtures thereof. Preferable solvent is aromatic hydrocarbons, more preferably toluene. Suitable solvent used for recrystallization of plerixafor base in step (vii) is selected from aliphatic lower alcohols CrC₄, or aliphatic ketones such as acetone, methyl -butyl ketone, methyl ethyl ketone, or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate etc or aliphatic halo hydrocarbons like dichloromethane, chloroform, carbon tetrachloride, ethylene chloride, etc or aromatic hydrocarbons selected from benzene, toluene, xylene, etc or aliphatic ethers like diethyl ether, methyl ethyl ether, diisopropyl ether, tetrahydrofuran, etc or mixtures thereof. Preferable solvent is the combination of lower aliphatic alcohols C1-C4 and acetone or acetone alone. BRIEF DESCRIPTION OF THE DRAWINGS

FIG.l: Powder X-ray diffraction pattern of plerixafor base prepared according to Examples 5, 6 and 7

Peaks in the powder X-ray diffraction spectrum having 2e values at about 11.4, 13.3, 18.1, 18.5, 21.7, 22.5, 22.9, and 24.9 ± 0.2 degrees.

FIG.2: DSC thermogram of plerixafor base prepared according to Examples 5, 6 and 7 DSC thermogram exhibits one endotherm between about 129°C and 135°C

FIG. 3: Infrared absorption spectrum of plerixafor base prepared according to Examples 5, 6 and 7

Absorption bands in the IR spectrum (KBr):

524, 757, 606, 811, 891, 919, 951, 1002, 1076, 1124, 1213, 1237, 1284, 1332, 1375, 1465, 1514, 2800, 2905, 3197, 3276, 3304 and 3431 cm^'1

X-ray powder diffraction spectra were measured on a Siemens d5000 X-ray powder difracto-meter having a copper-ka radiation ( 1.5406a).

DSC data was collected from Mettler Toledo; model: DSC 823^ef

IR spectra were recorded on Perkin Elmer; model: FT-IR paragon 1000

The details of the process of the invention are provided in the examples given below which are provided by way of illustration only and therefore should not be construed to limit the scope of the invention.

EXAMPLES

Example 1: Preparation of tris-(p-toluenesulfonyl)-l,4,8,ll- tetraazacyclotetradecane (5)

Cyclam (50g, 0.25 moles), methylene chloride (1250 mL), triethylamine (65.7g, 0.65 moles) were charged into 3L 3N RB flask and stirring was given. The solution of p- toluene sulfonyl chloride (95.3g, 0.50 moles) in methylene chloride (1250 mL) was added to the above reaction mass as dropwise during 50-60 minutes at room temperature. After addition reaction mass was stirred for another 4h then 2500 mL of water was added to the reaction mass and stirred for 15min. layers were separated and aq. layer was extracted with another 500 mL methylene chloride. The combined organic layer was washed with brine solution and layers were separated. Organic layer was dried over sodium sulphate; solvent was distilled off under reduced pressure to give off white coloured solid. The solid was leached with methanol (600 mL) at room temperature and filtered. The resulting solid was recrystallized from the solvent mixture of methylene chloride: hexane (1 :1) to afford pure tris-(p-toluenesulfonyl)-l, 4,8,11- tetraazacyclotetradecane (5) (60g, 36.4%); purity: 98% (HPLC). Ή NMR (400 MHz CDCI₃): 6 0.85 (brs, 1H), 1.71-1.74 (m, 2H), 1.96-2.03 (m, 21 1). 2.42 (s, 2H), 2.45 (s, 6H), 2.60-2.63 (t, 2H), 2.77-2.80 (t, 2H), 3.04- 3.10 (m, 4H), 3.16-3.19 (dd, 2H), 3.23- 3.27 (dd, 2H), 3.30-3.39 (m, 4H), 7.30-7.32 (m, 6H), 7.61-7.72 (m, 6H); ^,3C NMR (100 MHz CDCI₃): δ 21.43, 29.55, 29.72, 45.48, 46.06, 47.38, 47.84, 48.22, 48.76, 49.23. 51.36, 53.39, 127.08, 127.13, 129.64, 129.71, 134.96, 135.75, 136.72, 143.21, 143.34, 143.48; Mass (m z): 663.2 (M⁺ ion)

Example 2: Preparation of l,l'-[l,4-phenylenebis(methylene)]-bis[4,8 1-tris-(p- toIuenesulfonyl)-l,4,8,ll-tetraazacycIotetradecane (11)

Tris-(p-toluenesulfonyl)-l,4,8,l l-tetraazacyclotetradecane (5) (lOOg, 0.15 moles), N,N- dimethylformamide (700 mL), a, a'-dibromo-p-xylene (10) (25g, (0.094 moles), potassium carbonate (39.25g, 0.284 moles) were charged into 2L 3N RB flask, stirred the reaction mass for 3h at 80-85°C. Reaction mass was cooled to room temperature, water (1750 mL) was added and stirred for 30 min, solid was filtered off. The resulting solid was again leached with water (1750 mL). Then compound was dried at 65-70°C for 3h in a drier and recrystallized from methylene chloride followed by trituration with excess methylene chloride to give pure l,l '-[l,4-phenylenebis(methylene)]-bis[4,8,l l-tris-(p- toluenesulfonyl)-l,4,8,l l-tetraazacyclotetradecane (11) as white solid (59.5g, 40%); purity of the product: 97% (HPLC). ^!H NMR (400 MHz DMF-D7): δ 1.89-1 .92 (m, 4H), 2.1 1-2.15 (m, 4H), 2.58-2.63 (t, 24H), 2.85-2.89 (t, 4H), 3.32-3.42 (m, 18H), 3.47-3.49 (t. 4H), 3.76 (s, 4H), 7.43-7.92 (m, 28H); ¹³C NMR (100 MHz DMF-D7): δ 20.63, 20.67, 26.25, 27.91, 47.14, 47.32, 47.44, 47.71, 48.16, 50.63, 52.96, 59.03, 127.15, 127.28, 127.32, 129.19, 129.91 , 130.00, 130.05, 135.83, 136.59, 137.56, 143.49, 143.59, 143.76: Mass (m/z): 1428.0 (M⁺ ion) Example 3: Preparation of plerixafor octahydrobromide dihydrate (12)

1 , 1 '-[1 ,4-phenylenebis(methylene)]-bis[4,8, 11 -tris-(p-toluenesulfonyl)- 1,4,8,1 ltetraazacyclo-tetradecane (11) (80g, 0.056 moles), acetic acid (2400 mL) and 48% aq. hydrobromic acid (1600 mL) were charged into 5L 3N RB flask and refluxed the reaction mass (110-115°C) for 48h. Reaction mass was cooled to room temperature (25- 35°C), stirred for lh and solid was filtered from the reaction mass. The residue was washed with acetic acid (1200 mL) on suction and then suction dried for lh. The resulting solid was triturated with methanol (1200 mL) and filtered then dried at 70°C under high vacuum (750 mm Hg) to afford plerixafor octahydrobromide dihydrate (12) (60g, 90.3%); purity: 99% (HPLC). ^lH NMR (400 MHz D₂0): δ 2.12-2.20 (m, 8H). 3.26- 3.56 (m, 32H), 4.35 (s, 4H), 7.61 (s, 4H); ^l3C NMR (100 MHz D₂0): δ 18.28, 18.87, 37.37, 37.61, 41.01, 41.22, 41.59, 44.47, 47.62, 58.28, 130.99, 131.81; Mass (m/z): 585 (M+ H⁸¹Br), 584 (M+ H⁸⁰Br), 583 (M+ H⁷⁹Br).

Example 4: Preparation of plerixafor base (1)

Plerixafor octahydrobromide dihydrate (12) (57g, 0.048 moles), water (570 mL) were charged into 1L RB flask, stirred to dissolve at room temperature. The resulting solution was filtered off through hyflow bed for particles free. The filtrate was transferred into 2L 3N RB flask pH was adjusted to >13.0 by adding 25% aq. sodium hydroxide solution (570 mL of 25% aqueous sodium hydroxide solution was consumed) to form a white coloured suspension. The resulting suspension was extracted into toluene (1140 mL) at 60-65°C and layers were separated. Organic layer was dried over sodium sulphate, filtered through sintered funnel using 0.45μ filter paper and solvent was evaporated under reduced pressure to give a white coloured solid. The resulting solid was triturated with toluene (120 mL) to afford plerixafor base (1) (20.5g, 85%), purity: 99.72% (HPLC). Ή NMR (400 MHz CDC1₃): δ 1.64-1.69 (m, 4.H), 1.83-1.85 (m, 4H), 2.46-2.80 (m, 38H), 3.55 (s, 4H), 7.25 (s, 4H); ¹³C NMR (100 MHz CDC1₃): δ 26.31, 28.78, 47.32, 48.07, 48.94, 49.05, 49.18, 50.66, 52.1, 54.51, 57.32, 128.96, 137.13; Mass (m/z): 503.5 (M+l ion)

Example 5: Purification of plerixafor base (1)

Plerixafor base (1) (18.5g) obtained from example 4 and methanol (185 mL) were charged into a 500 mL RB flask and stirred to dissolve. The resulting solution was filtered off for particles free and the solvent from filtrate was concentrate at 65-70°C under vacuum to yield white colured solid. The process was repeated one more time. Then the resulting solid was triturated with acetone (185 mL) and filtered then dried under high vacuum (750 mm Hg) for 5-6h to afford high pure plerixafor base (17.5g, 95%); purity: 99.88% (HPLC). Example 6: Purification of plerixafor base (1)

Plerixafor base (1) (20g) obtained as per example 4 and isopropyl alcohol (200 mL) were charged into a 500 mL RB flask and stirred to dissolve. The resulting solution was filtered off for particles free and the solvent from filtrate was concentrate at 65-70°C under vacuum to yield white colured solid. The process was repeated one more time. Then the resulting solid was triturated with acetone (200 mL) and filtered then dried under high vacuum (750 mm Hg) for 5-6h to afford high pure plerixafor base (18.8g, 94%); purity: 99.83% (HPLC).

Example 7: Purification of plerixafor base (1)

Plerixafor base (1) (22g) and methanol (22 mL) were charged into a 500 mL RB flask and stirred to dissolve at 50-55°C. The resulting solution was cooled to room temperature and was added acetone (220 mL), stirred for lh and filtered solid. Then the resulting solid was dried under high vacuum (750 mm Hg) for 5-6h to afford high pure plerixafor base (14g, 64%); purity: 99.86% (HPLC). Advantages of the present invention

1. Present invention provides improved process for the preparation of high pure plerixafor base (> 99.8%).

2. Present process provides simple, improved and efficient process suitable for plant scale

3. Present process avoids column chromatographic technique which is time consuming and limits the batch size

4. Present process provides simple crystallization techniques to isolate the compound at each step.

5. Present process provides high pure plerixafor base (> 99.8%) which suitable for pharmaceutical compositions.

Claims

CLAIMS We claim

1. Improved and commercially viable process for the preparation of > 99.8% pure plerixafor base of formula (1)

1

which comprises,

i) reaction of cyclam of formula (8)

8

with p-toluene sulfonyl chloride of formula (9)

9

in the presence of base in an organic solvent at 20-100°C to get tris-(p- toluenesulfonyl)- 1 ,4,8, 11 -tetraazacyclotetradecane of formula (5)

purification of crude tris- (p-toluenesulfonyl)-l, 4,8,11- tetraazacyclotetradecane of formula (5) by trituration and /or crystallization from an organic solvent to get pure tris-(p-toluenesulfonyl)- 1,4,8,1 1- tetraazacyclotetradecane of formula (5)

reaction of compound of formula 5) with with a, a'-dibromo-p-xylene (10)

10

in the presence of base in an organic solvent at elevated temperatures at 0- 150°C to get l,l'-[l,4-phenylenebis(methylene)]-bis[4,8,l l-tris-(p- toluenesulfonyl)- 1,4,8,11 -tetraazacyclotetradecane of formula (11)

purification of compound of formula (11) by recrystallization from a suitable solvent

reaction of compound of formula (11) with a strong acid at elevated temperature to get plerixafor acid addition salt of formula (12)

12 reaction of compound of formula (12) with a base in the presence of aqueous solvent medium to get pure plerixafor base of formula (1)

vii) recrystallization of above obtained pure plerixafor base from a suitable solvent to get pharmaceutically acceptable grade high purity (>99.8%) plerixafor base as a crystalline solid.

2. The process according to claim 1 wherein the solvent used in step (i) is selected from chlorinated hydrocarbons such as dichloromethane, chloroform, ethylene chloride, etc. or aromatic hydrocarbons like toluene, xylene, etc. Preferable solvent medium is chlorinated solvents like dichloromethane and chloroform, more preferable solvent is dichloromethane.

3. The process according to claim 1-2 wherein the base used in step (i) is selected from organic bases such as tertiary alkyl amines such as triethylamine, tributylamine, diisopropylethylamine, hetero aromatic amines such as pyridine, lutidine, collidine, etc., preferably tertiary alkyl amines more preferably triethyl amine.

4. The process according to claim 1-3 wherein the trituration solvent used for purification of compound of formula (5) in step (ii) is selected from C C₄ alkanols, preferably methanol.

5. The process according to claim 1-4 wherein the recrystallization solvent for compound of formula (5) in step (ii) is selected from Ci-C₄ alkanols or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate etc or aliphatic ketones such as acetone, methyl- butyl ketone, methyl ethyl ketone etc or aliphatic halo hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, ethylene chloride, etc. or aliphatic hydrocarbons C₅-C or aromatic hydrocarbons like toluene, xylene or mixtures thereof. Preferable solvent is combination of dichloromethane and hexane in the ratio of 1 : 1.

6. The process according to claim 1-5 wherein the base used in step (iii) is selected from inorganic bases such as alkali metal carbonates such as sodium or potassium carbonate or alkali earth metal carbonates such as calcium carbonate, barium carbonate or organic bases such as tertiary alkyl amines like triethylamine, tributylamine, diisopropylethylamine, hetero aromatic amines such as pyridine, lutidine, collidine, etc., preferably alkali metal carbonates, more preferably potassium carbonate.

7. The process according to claim 1-6 wherein the mole ratio of compound of formula (5) in step (iii) to compound of formula (10) is 1.2 to 2.5 preferably 1.5-1.8.

8. The process according to claim 1-7 wherein the reaction temperature in step (iii) is ranged from 0-150°C, preferably 40-85°C, more preferably 75-85°C.

9. The process according to claim 1-8 wherein the solvent used in step (iii) is selected from polar aprotic solvents such as acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide and aromatic hydrocarbons like toluene, xylene, etc., preferably acetonitrile or Ν,Ν-dimethylformamide, more preferably N,N-dimethylformamide.

10. The process according to claim 1-9 wherein the suitable recrystallization solvent used for purification of compound of formula (11) in step (iv) is selected from aliphatic halo hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, ethylene chloride etc. preferably dichloromethane.

11. The process according to claim 1-10 wherein the suitable reagent solvent in step (v) is the combination of aq. hydrobromic acid and acetic acid.

12. The process according to claim 1-11 wherein the suitable solvent used for trituration of compound of formula (12) in step (v) is selected from C_!-C₄ alkanols, or aliphatic ketones such as acetone, methyl-butyl ketone, methyl ethyl ketone etc or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate etc or aliphatic halo hydrocarbons selected from dichloromethane, chloroform, carbon tetrachloride, ethylene chloride, etc or aliphatic hydrocarbons selected from C₅-C₇ or aromatic hydrocarbons selected from toluene, xylene or aliphatic ethers like diethyl ether, methyl ethyl ether, diisopropyl ether, tetrahydrofuran etc or mixtures thereof. Preferable solvent is Ci-C alkanols, more preferably methanol.

13. The process according to claim 1-12 wherein the suitable base used in step (vi) for liberation of plerixafor base of formula (1) is selected from alkali metal or alkali earth metal carbonates, hydroxides, or aq. ammonia solution. Preferably alkali metal hydroxides, more preferably sodium hydroxide or potassium hydroxide.

14. The process according to claim 1-13 wherein the suitable pH in step (vi) to liberate plerixafor base of formula (1) is ranging from 9-14, preferably 12-14 more preferably 13- 14.

15. The process according to claim 1-14 wherein the suitable solvent used in step (vi) to extract the plerixafor base of formula (1) is selecting from aromatic hydrocarbons such as toluene, xylene or aliphatic esters like ethyl acetate, n-propyl acetate, n-butyl acetate etc. preferably aromatic hydrocarbons, more preferably toluene.

16. The process according to claim 1-15 wherein the suitable temperature to extracting the compound of formula (1) in step (vi) is ranging from 25-100°C, preferably 50-80°C and more preferably 55-70°C.

17. The process according to claim 1-16 wherein the suitable solvent used to triturate the plerixafor base of formula (1) in step (vi) is selected from aliphatic ketones such as acetone, methyl butyl ketone, methyl ethyl ketone etc or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate etc or aliphatic hydrocarbons selected from C₅- C₇ or aromatic hydrocarbons selected such as toluene, xylene or aliphatic ethers like diethyl ether, methyl ethyl ether, diisopropyl ether, tetrahydrofuran or mixtures thereof, preferably aromatic hydrocarbons, more preferably toluene.

18. The process according to claim 1-17 wherein the suitable solvent to recrystallize plerixafor base of formula (1) in step (vii) is selected from Q-C₄ alkanols or aliphatic ketones such as acetone, methyl butyl ketone, methyl ethyl ketone etc or aliphatic esters such as ethyl acetate, isopropyl acetate, butyl acetate etc or aromatic hydrocarbons such as toluene, xylene or aliphatic ethers like diethyl ether, methyl ethyl ether, diisopropyl ether, tetrahydrofuran or mixtures thereof. Preferable solvent is the combination of alkanols Cj-C₄ and acetone or acetone alone.

19. Solid state properties of plerixafor base prepared according to the process of claim 1 is being characterized by Peaks in the powder X-ray diffraction spectrum having 2e values at about 11.4, 13.3, 18.1, 18.5, 21.7, 22.5, 22.9, and 24.9 ± 0.2 2e; bands in the infra red (IR) absorption spectrum (KBr) with peaks at cm^"1 _, and DSC thermogram exhibits one melting endotherm between about 129°C and 135°C; and bands in the infra red (IR) absorption spectrum (KBr) with peaks at 524, 757, 606, 811, 891, 919, 951, 1002, 1076, 1124, 1213, 1237, 1284, 1332, 1375, 1465, 1514, 2800, 2905, 3197, 3276, 3304 and 3431 cm

20. A pharmaceutical composition comprising a therapeutically effective amount of the plerixafor of claim 1 or a pharmaceutically acceptable salt thereof.