WO2016056023A2

WO2016056023A2 - Intermediates and processes to prepare micafungin

Info

Publication number: WO2016056023A2
Application number: PCT/IN2015/000379
Authority: WO
Inventors: Lakshmi Prasad ALAPARTHI; Anand Vijaykumar MANTRI; Kumar HUCHANNA Yogish; Talluri Bhushaiah CHOWDARY; Gaurav Kulkarni; Ganga Ramu VASANTHAKUMAR
Original assignee: Alaparthi Lakshmi Prasad
Priority date: 2014-10-07
Filing date: 2015-10-07
Publication date: 2016-04-14
Also published as: EP3226885A4; EP3226885A2; WO2016056023A3

Abstract

The present invention relates to active esters of compound of Formula I-A and Formula I-B which are used as key intermediates in the synthesis of Micafungin, an antifungal agent and process of preparation of said active esters. The invention also relates to process of preparing Micafungin from said active esters.

Description

Field of the invention

[0001 ] The present invention relates to active esters of compound of Formula I which are used as key intermediates in the synthesis of Micafungin, an antifungal agent and process of preparation of said active esters. The invention also relates to process of preparing Micafungin from said active esters.

Formula I (a) R', R" = CH₃

(b), R', R" = C_f,H,

Background of the invention

[0002] Micafungin (MICA) with CAS Registry Number: 2351 14-32-6 and IUPAC name as {5-[(l S,2S)-2-[(3S,6S,9S,l 1R,15S,18S,20R,21R,24S,25S,26S)- 3 [( 1 R)-2-carbamoyl- 1 -hydroxyethyl]- 1 1 ,20,21 ,25-tetrahydroxy- 15-[( 1 R)- 1 - hydroxyethyl]-26-methyl-2,5,8,14,17,23-hexaoxo-18-[(4-{5-[4- (pentyloxy)phenyl]-l ,2-oxazol-3-yl}benzene)amido]-l, 4,7, 13,16,22- hexaazatricyclo[22.3.0.09,13]heptacosan-6-yl]- 1 , 2-dihydroxyethyl]-2- hydroxyphenyl}oxidanesulfonic acid is an echinocandin antifungal is used to treat a variety of fungal infections (such as candidemia, esophageal candidiasis). It is also used to prevent fungal infections in people who have undergone bone marrow or stem cell transplant, since these people have weak immune systems and hence at the higher risk of fungal infections. It works by way of concentration-dependent inhibition of 1 ,3-beta-D-glucan synthase resulting in reduced formation of 1 ,3-beta-D-glucan, which is an essential polysaccharide- comprising one-third of the majority of Candida spp. cell walls. This decreased glucan production leads to osmotic instability and thus cellular lysis.

Different routes of preparation of Micafungin are disclosed in the art. [0003] US6107458 patent describes polypeptide compound. The patent describes several reactive derivatives of 4-(5-(4-(pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (PPIB) such as reactive derivative at the carboxy group or a salt thereof. The 1 -hydroxy benzotriazole has been used as reactive derivative of PPIB. The reactive derivative of PPIB is typically formed in the presence of l -ethyl-3-(3- dimethylaminopropyl) carbodiimide (EDCI). The peptide compounds are prepared by reaction wherein the amino compounds are treated with R'-OH compounds by elimination reaction of amino protective group in R¹.In this patent Micafungin is obtained from reaction of CMICA/FR- 179642 with the benzotriazole- active ester of PPIB in the presence of 4-dimethylaminopyridine (DMAP).

[0004] Similar procedure of the conversion of CMICA/FR- 179642 with the benzotriazole active ester of PPIB with yields in the range of 53.3 % and 75 %, respectively is reported in the literature (Kanasaki et al, J. Antibiotics 1999, 52, 674 and Tomishima et al, Bioorg. Med. Chem. Lett. 2008, 18, 2886).

[0005] WO2004014879 describes process for preparation of intermediate compound used for producing an antifungal agent and a process for preparing antifungal agent from the said intermediate compound. This patent application discloses reaction of CMICA/FR- 179642 with the benzotriazole active ester of compound of Formula III, wherein R² is lower alkoxy or higher alkoxy, R⁴ is carboxy, A¹ is an aromatic bivalent group, heterocyclic bivalent 5 group or cyclo(lower)alkane bivalent group, and A is an aromatic bivalent group, heterocyclic bivalent group or cyclo(lower)alkane bivalent group to provide

MICA.

(III)

or its reactive derivative

at the carboxy group

or a salt thereof [0006] WO2013034670 describes various active esters of PPIB, more particularly those which allow a one-pot synthesis from PPIB to give an antifungal agent preferably MICA, or a salt thereof, preferably without the need to isolate and/or purify the active ester of PPIB before the conversion with another key intermediate, preferably CMICA. Some of the active esters represented therein are as follows:

Notwithstanding the prior art, the present invention is neither taught nor rendered obvious thereby.

[0007] The present invention relates to active esters of PPIB, novel key intermediates, the process for their preparation and preparation of MICA from these active esters. The active esters are used either in situ form or they are isolated and purified and used in the preparation of Micafungin in isolated form. One such active ester has been isolated, is shelf stable and can be stored in a dry condition for several months after its preparation.

Object of the invention

[0008] The first object of the present invention is to provide novel active esters of 4-(5-(4-(pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (PPIB), in particular novel key intermediate of Micafungin, which is an antifungal agent. The novel active esters are esters of 4-(5-(4-(pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (PPIB). The active ester is prepared "in situ " and reacted further to produce Micafungin or is isolated and stored before use. One such isolated active ester is shelf stable and can be stored for further synthesis of Micafungin. [0009] Second object of the present invention is to provide process to prepare novel active esters of PPIB, which is simple and economical.

[0010] Third object of the present invention is to provide a process to prepare Micafungin (MICA) from novel active esters of PPIB with another key intermediate, preferably CMICA/FR- 179642 or a salt thereof in good yield.

Summary of the invention

[001 1] According to the first aspect, the present invention provides novel key intermediates, in particular novel active esters of PPIB represented by Formula I as below:

Under this aspect, the active esters of PPIB are formed "in situ " or it is isolated compound. The active ester of Formula I wherein R' and R" both are methoxy is successfully isolated, purified and characterized. This ester is found storage stable. The isolated ester is further characterized for physicochemical and spectroscopic methods. The active ester purity was confirmed by RP-HPLC and it is further characterized by MS, Ή NMR. This active ester is shelf stable and can be stored in a dry condition for months after its preparation. This would enable to prepare and store the active ester and use it when needed for synthesis of Micafungin.

The active ester of Formula I of the present invention is selected from

Formula IA Formula IB [0012] According to the second aspect, there is provided process of preparation of novel compounds of active esters of Formula I . from 4-(5-(4- (pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (Formula III).

Formula III

The process for preparation of active esters of Formula I comprises reaction of the compound of formula III with a triazine salt selected from 2-chloro-4,6- dimethoxy-l,3,5-triazine (CDMT) or 2-chloro-4,6-diphenyloxy-l,3,5-triazine (CDPT) in presence of base and solvent.

[0013] The solvent is aprotic solvent selected from the group consisting of tetrahydrofuran (THF), dimethyl formamide (DMF), dimethylacetamide, toluene, 2-methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and mixtures thereof. The base is selected from the group consisting of N-methylmorpholine, Ν,Ν,Ν,Ν- tetramethylguanidine, pyridine, JV-methyl-2-pyrrolidone (NMP), triethylamine, 4- picoline, 4-dimethylaminopyridine (DMAP), toluene, N-methylpiperidine and N,N, N,N-tetramethylethylenediamine, and combination thereof.

The preferred base is vV-methylmorpholine and the preferred solvent is DMF.

[0014] The process for preparation of active esters of Formula I A comprises reaction of PPIB of Formula III with CDMT in presence of base in DMF as solvent is as follows:

4-(5-(4-{pentyloxy)phenyI)isoxazol-3-yl)benEoic add

Formula III CDMT

W-methylmorpholine

DMF

This step viz. isolation is optional

Formula IA

[0015] In the above reaction, to prepare the active ester compound of Formula IB, 2-chloro-4,6-diphenyloxy-l ,3,5-triazine (CDPT) is used instead of 2-chloro-4,6- dimethoxy-l,3,5-triazine (CDMT).

The process for preparation of the active esters of compound of Formula I proceeds in two steps.

The first step involves reacting, the triazine compound of formula (A) with a compound of formula (B) to generate a triazine salt of formula (C).

The process for preparing the triazine salt of formula (C) is represented in the below scheme.

(A) (B) (C)

a, R', " = OCH₃

b, R',R" = OC3H5 where each of Ri, R₂, R₃ independently is hydrogen, alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups or alternatively Ri, R₂ and R₃ together with Nitrogen or any two of the Ri, R₂ and R₃ together with Nitrogen form a ring which can be heterocycloalkyl, or heterocyclic and any such ring is optionally substituted by alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups, nitro, halo, amino or substituted amino groups or alternatively Ri, R₂ and R₃ together with Nitrogen form guanidine or substituted guanidine.

Preferably, the compound of formula (B) is a base and preferably the base is N- methylmorpholine. The N-methylmorpholine reacts with triazine compound of formula (A) and generates "in situ " the compound of formula (C).

[0016] Accordingly, N-methylmorpholine is reacted with 2-chloro-4,6-dimethoxy- 1 ,3,5-triazine (CDMT) [or 2-chloro-4,6-diphenyloxy-l,3,5-triazine (CDPT)] to produce 4-(4,6-dimethoxy-l ,3,5-triazin-2-yl)-4-methylmorpholin-4-iumchloride, DMTMM [or 4-(4,6-diphenoxy-l ,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride, DPTMM] as represented in below scheme.

CDMT NMM (DMTMM)

In second step, the triazine salt, DMTMM or DPTMM generated by reaction of a base with CDMT or CDPT can be isolated or reacted "in situ" [(DMTMM) or (DPTMM)] further with PPIB compound of Formula III to produce the corresponding active ester. Thus, the present inventors have successfully isolated and characterized the active ester prepared by reacting DMTMM and PPIB, a Formula III compound as follows:

(DMTMM) or DMTMM Formula III

Formula IA

The active ester which is compound of Formula IA can be further isolated optionally.

Formula IA

[0017] Similar to above, when a base used is other than N-methyl morpholine, any salt generated by reaction of a base with CDMT or CDPT can be isolated. Such isolated salt is reacted with the compound of Formula III to produce active ester of Formula I. In this process DMTMM or DPTMM or any such salt is used as a coupling agent for preparation of an active ester. [0018] Further aspect of the invention is to provide process of preparation of an antifungal agent, Micafungin represented by the compound of Formula II from the novel active ester either "In situ" or in isolated form as follows:

Formula II

Alternatively, isolated novel active ester of Formula IA is reacted with FR-179642 to produce Micafungin.

Formula IA

Formula II

[0019] The novel active esters of the present invention which are the active forms of the acid are generated in situ using CDMT or CDPT as a coupling agents and Micafungin is prepared from the active esters prepared from CDPT or any salt of CDMT / CDPT and a base.

Brief description of the figures:

[0020]

Fig. 1 represents 1H-NMR of Formula IA in CDC1₃

Fig. 2 represents Ή-NMR of Formula IA in CDC1₃ (Expanded region from 6.3 to 8.5 5 region of Fig.1).

Fig. 3 represents 1H-NMR of Formula IA in CDCI3 (Expanded region from 0.5 to 4.5 δ region of Fig.1 ).

Fig. 4 represents RP-HPLC profile of Formula IA

Fig. 5 represents MS spectra of Formula IA

Fig. 6 represents stability of Formula IA by HPLC profile. Detailed Description of the Invention

[0021] The details of the invention are as set forth.

All the technical and scientific terms used herein above have the meaning as commonly understood by a person skilled in the art to which the invention belongs, unless otherwise defined in this specification.

Following abbreviations are used and should be construed accordingly.

CDMT: 2-chloro-4,6-dimethoxy-l ,3,5-triazine

CDPT: 2-chloro-4,6-diphenyloxy-l,3,5-triazine

DMTMM:4-(4,6-dimethoxy-l ,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride

DPTMM:4-(4,6-diphenyloxy-l ,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride

NMM: N-methylmorpholine

TMG: N,jV,N,N-tetramethylguanidine

PPIB: 4-(5-[4-(pentyloxy)phenyl]-isooxazol-3-yl)benzoic acid

[0022] Micafungin is an echinocandin antifungal agent, is used to treat a variety of fungal infections (such as candidemia, esophageal candidiasis). It is also used to prevent fungal infections in people who have undergone bone marrow or stem cell transplant, since these people have weak immune systems and hence at the higher risk of fungal infections. It works by way of concentration-dependent inhibition of 1,3-beta-D-glucan synthase resulting in reduced formation of 1 ,3- beta-D-glucan, which is an essential polysaccharide comprising one-third of the majority of Candida spp. cell walls. This decreased glucan production leads to osmotic instability and thus cellular lysis.

[0023] The first aspect of the present invention relates to novel active esters represented by a compound of Formula I. The active ester of compound of formula I are used to prepare Micafungin of Formula II. The active esters of Formula I are prepared "in situ " and reacted further as they are or the active esters of Formula I are isolated and further reacted.

Formula I a, R', R" = CH₃

b, R', R" = C₆H₅

[0024] Particularly, when R' and R" are -CH_3; the active ester is represented below as Formula IA, such active ester has been successfully isolated, purified and characterized.

Formula IA

[0025] This active ester is shelf stable and can be stored for several months after its preparation. This would enable one to prepare and store the active ester and use it when needed for synthesis of Micafungin. This would also enable one to transport active ester from one lab to another for further scale up of Micafungin from development scale to commercial level or one commercial scale to higher commercial scale. This would also enable one to obtain ready key intermediate of Micafungin from market for further synthesis. Further this ester provides means for one pot synthesis of Micafungin.

[0026] Further, the active ester of Formula I is subjected to acylation reaction with FR- 179642 of Formula IV to produce Micafungin, preferably in presence of a base selected from diisopropylethyl amine, N-methyl morpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, triethylamine and collidines, and any combination thereof. The preferred base is diisopropylethyl amine.

[0027] The reaction completes in about 3 to 5 h and results with quantitative yield of high purity (crude purity is at least 95%) Micafungin.

The active ester of Formula 1A is characterized as follows:

Physical characteristics

1. Appearance: White amorphous power

2. Melting point: 1 12- 1 18 °C

Spectroscopic characteristic:

An active ester of Formula I A is characterized by studying ¹ H-NMR spectra, mass spectra, and RP-HPLC profile; the details of which are provided in figures.

1H-NMR spectra

The Ή NMR was recorded on Bruker 400 MHz using CDC1₃ as solvent. The details ofΉ NMR spectra are provided in table 1 as follows:

Table 1 : Details of 1H NMR spectra

*Additional peaks are due to water and solvent at δ 1 .56 and 7.26 respectively.

RP-HPLC profile Purity of the active ester was confirmed by RP-HPLC equipped with gradient elution capability, ultraviolet spectrophotometer as detector and an auto sampler with Zodiac C18, (250 x 4.6mm, 5 μ), 100A or equivalent (USP LI) column and Shimadzu LC 201 OA HT system. The chromatographic parameters used for the study is as follows:

Flow rate : l .O mL/minute

Detection : UV at 220 nm

Injection Volume : 10 μL

Column Oven Temperature : Ambient

Run time : 32.50 min

The gradient is provided under table 2.

Table 2: Gradient Program*

*A is mobile phase containing 0.01 % trifluroacetic acid in Milli Q water and B is 0.01 % trifluroacetic acid in acetonitrile. The novel active ester elutes at the retention time of 22.5.

[0028] In second aspect, the invention provides a process for in situ preparation of novel active ester.

Process for "in situ " preparation of active ester is as follows and involves preparation of active ester followed by isolation.

I] Preparation of active ester

An active ester in accordance with the present invention is prepared by process in which compound of the Formula III viz. PPIB is reacted with 2-chloro-4,6- dimethoxy-l ,3,5-triazine (CDMT) or 2-chloro-4,6-diphenoxy-l,3,5-triazine (CDPT). The step is carried out in a solvent, preferably in an aprotic solvent, selected from tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide, toluene, 2-methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof, and is preferably tetrahydrofuran. The step is carried out in presence of base. The base is selected from N-methylmorpholine (NMM), N,N,N,N-tetramethylguanidine, pyridine, 4-picoline, 4- dimethylaminopyridine (DMAP), N-methylpiperidine and Ν,Ν,Ν,Ν- tetramethylethylenediamine, trimethylamine and any combination thereof, and is preferably N-methylmorpholine (NMM).

[0029] Thus, the novel active ester of the present invention which is an active form of the acid is generated in situ using CDMT or CDPT as a coupling agent. Further the novel ester prepared "in situ" can be isolated by evaporating the reaction mixture to dryness. The crude mixtures were dissolved in aprotic solvent such as ethyl acetate and solution is filtered to remove unreacted reagents and salts generated. The filtrate was evaporated to dryness and the solid obtained was stored in cold and anhydrous condition for prolonged usage.

[0030] The active ester of Formula IA when CDMT or its derivative (DMTMM) is used as a coupling agent as follows: Similarly, CDPT and its derivative DPTMM can also be used as coupling agents. Also various other salts made by reaction of CDMT and CDPT with other bases can be used as coupling agents. The reaction is preferably carried out in aprotic solvents, most preferred are THF or DMF.

4-(5-<4-(pentyloxy)phen 1)lsoxazol-3-y1)benzoic acid

Formula III CDMT

N-methylmorpholine and THF/DMF

Formula IA

optionally isolated

Formula IA

[0031] The above process is a two steps reaction.

In the first step 2-chloro-4,6-dimethoxy-l ,3,5- triazine (CDMT) is reacted with N-methylmorpholine to form 4-(4,6-Dimethoxy-l ,3,5-triazin-2-yl)-4- methylmorpholin-4-ium chloride salt (DMTMM). DMTMM is also referred as derivative of CDMT.

CDMT NMM (DMTMM)

DMTMM salt can be further reacted "in situ" (DMTMM) or isolated for further reaction. [0032] In the second step DMTMM salt "m situ" or in isolated form is reacted with compound of Formula III which yields the formation of active ester of Formula I.

DMTMM or (DMTMM) Formula III

The active ester which is compound of Formula I can be further isolated.

[0033] In a similar way, in place of CDMT, 2-chloro-4,6-diphenyloxy- 1,3,5 - triazine, CDPT can be used to produce 4-(4,6-diphenyloxy-l,3,5-triazin-2-yl)-4- methylmorpholin-4-ium chloride, DPTMM, which further can be used to prepare following active ester. This active ester of formula IB is either isolated or prepared insitu and further converted into Micafungin. Preferably the compound of Formula IB is used for preparation of Micafungin without isolation.

Formula IB

[0034] Further, apart from N-methylmorpholine, other bases can be used to produce corresponding salt which is equivalent to DMTMM (4-(4,6-dimethoxy- l ,3,5-triazin-2-yl)-4-methylmorpholin-4-iumchloride) or DPTMM (4-(4,6- diphenylo y- l ,3,5-triazin-2-yl)-4-methylmo holin-4-iumchloride). Such salts are further reacted with Formula III compound to produce active esters.

The general scheme in which a base is used with CDMT or CDPT to produce various e uivalents of DMTMM or DPTMM is as follows.

a, R',R" = OCH3

b, R',R" = OC₆H₅

where each of R[, R₂, R₃ independently is hydrogen, alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups or alternatively R| , R₂ and R₃ together with Nitrogen or any two of the Rl , R2 and R3 together with Nitrogen form a ring which can be heterocycloalkyl, or heterocyclic and any such ring is optionally substituted by alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups, nitro, halo, amino or substituted amino groups or alternatively Ri, R₂ and R₃ together with Nitrogen form guanidine or substituted guanidine.

II] Isolation

[0035] The isolation and purification process of active esters would depend upon the solvents in which such active ester is prepared. The solvent is preferably aprotic and can be one selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide, toluene, 2- methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof. Preferably solvent is dimethylformamide or tetrahydrofuran. When tetrahydrofuran is used as an^' aprotic solvent, the active ester prepared can be obtained by evaporating the solvent to obtain residue. The residue is further dissolved in another solvent, preferably aprotic such as ethyl acetate and purified to obtain pure active ester. When dimethylformamide is used as a solvent, first the active ester dissolved therein is precipitated by adding water. The precipitated active ester is dissolved in a solvent, preferably aprotic such as ethyl acetate and purified to obtain pure active ester.

Washings can be given before purification to remove unreacted materials.

Purity of active ester is usually about or greater than 95 %, preferably greater than

97 %.

[0036] The most desired properties of active esters of Formula I include i) purity of esters without subjecting to purification step and ii) storage stability for at least 1 month, preferably greater than 3 months and most preferably greater than 6 months.

[0037] The stability of active ester of Formula IA at 2-8°C for 13 months as recorded is represented in figure 6. Figure 6 represents HPLC purity of active ester of formula IA having purity 99.3% by HPLC is stale after 13 month. Thus, the active ester of Formula IA is stable upto 13 months with about 1 % degradation in purity by HPLC. In conclusion, the stability of active ester of Formula IA for 13 month storage at 2-8 degree shows degradation of only ~1% was observed. The active esters of the present invention are further reacted with the compound .of Formula IV (FR- 179642) to produce Micafungin. This reaction is carried out with either in situ or with isolated ester. When the ester is prepared and reacted in situ, its formation is confirmed by HPLC method.

Further, the invention relates to the process for preparation of an antifungal agent (MICA) from novel active ester, compound of Formula I.

[0038] According to this aspect of the present invention, Micafungin (MICA) of Formula II is prepared from the novel active ester (compound of Formula IA) by reacting with FR-179642 compound of Formula IV as follows:

Formula IA

Isolated novel active ester can be similarly reacted with Formula IV compound (FR -179642) to produce Micafungin.

Formula II

Further, invention relates to process of preparing Micafungin of Formula II from the active ester of Formula IA of the present invention. The process can be described in details as follows:

Process for preparation of an antifungal agent:

[0039] The process for the preparation of an antifungal agent comprises reacting the active ester of Formula IA with compound of Formula IV (FR- 179642) preferably in presence of a base selected from diisopropylethyl amine, N- methylmorpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, and collidines, and any combination thereof. The most preferred base diisopropylethyl amine.

Formula II

[0040] Similar to above an active ester of Formula IB is prepared from CDPT can produce DPTMM which is further reacted with PPIB or compound of Formula III to produce active ester which is acylated using compound of Formula IV (FR- 179642) to produce Micafungin as follows:

[0041] Apart from N-methylmorpholine, other bases can be used to prepare several equivalents of DMTMM or DPTMM and these equivalents are further reacted with the FR 179642 or compound of Formula IV to produce Micafungin. The DMTMM or DPTMM or their equivalents produced by using bases other than N-methylmorpholine can be isolated or reacted "in situ " with the FR 179642 or compound of Formula IV to produce Micafungin.

[0042] The present invention provides processes to prepare Micafungin using active esters of Formula IA and Formula IB. The active esters are reacted either

"in situ" or in isolated form. The active esters are obtained and isolated in pure form even in crude state. The purity is above 95 %. These esters are storage stable and can be stored up to or even more than one year at 2-8°C.

[0043] Further, Micafungin can be converted into its sodium salt by following methods.

Process for preparation of sodium salt of Micafungin:

Micafungin, the compound of Formula II is dissolved in solvent such as DMF and sodium 2-ethylhexanoate is added in one portion and stirred at temperature below 25°C for 2-3 h. The mixture is diluted with solvent such as ethyl acetate. The sodium salt of Micafungin compound is precipitated out. The precipitated solid is filtered and washed with ethyl acetate to remove excess reactants and dried. The dried compound is further dissolved in water and lyophilized.

Alternatively, compound of the Formula II is reacted or titrated against sodium salts and/ or hydroxides.

[0044] The present invention also provides process for preparation of Micafungin comprising the steps of

a) reacting the compound of Formula IV in a solvent with the compound of Formula I in presence of a base to get Micafungin;

Formula I (a) R', R" = CH,

(b), R\ R" = C₆H_S

b) optionally purifying Micafungin and

c) optionally converting Micafungin or purified Micafungin into pharmaceutically acceptable salts.

[0045] The solvent used in this process of preparing Micafungin is selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide, toluene, 2-methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and mixtures thereof and base is selected from the group consisting of N- methylmorpholine, N,N,N, N-tetramethylguanidine, pyridine, N-methyl-2- pyrrolidone (NMP), triethylamine, 4-picoline, 4-dimethylaminopyridine (DMAP), toluene, JV-methylpiperidine and N, N,N, N-tetramethyl ethyl enediamine, and combination thereof. The reaction is carried out overnight at room temperature.

[0046] Alternatively, the present invention provides a process for preparation of Micafungin comprising reacting 4-(5-(4-(pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (PPIB), 2-chloro-4,6-dimethoxy-l,3,5-triazine (CDMT) or 2-chloro-4,6- diphenyloxy-l,3,5-triazine (CDPT), the compound of Formula IV in presence of a base and isolating Micafungin which is optionally purified.

Further this reaction is carried out at room temperature or at 40°C or at 60°C or at 0-5°C. The highly pure Micafungin is obtained when the mixture is allowed to stir for overnight at room temperature or at 25-30°C.

[0047] Micafungin prepared according to the present invention is converted into its pharmaceutically acceptable salt. The sodium salt of Micafungin is prepared by stirring a solution of Micafungin in alcohol such as methanol and charging with, aqueous solution of sodium 2-ethylhexanoate at 0-5 °C and stirring the mixture for 16 hrs at room temperature.

The non-limiting examples according to present invention are as follows:

Examples

[0048] Example 1 : Preparation of active ester

Method-I (in situ) : To a stirred solution of PPIB (3.51g 10.0 mmol) in THF/DMF (140 mL, 40 vol.) under N₂ was charged CDMT (2.1 g, 12.0 mmol, 1.2 eq.) and continued stirring for 15 min at room temperature. Reaction mixture was cooled to 10-15 °C and NMM (1.65 mL, 1.5 eq.) was charged slowly. The mixture was allowed to stir for overnight.

Workup and purification:

THF method: Solvent was evaporated and residue dissolved in dichloromethane /chloroform/ethyl acetate (30 volumes) and or other aprotic solvents. The mixture was filtered and the filtrate was washed with water and brine, dried over anhydrous sodium sulfate and evaporated to dryness by rotary evaporator.

DMF method: Reaction mixture was poured into ice water and the solid obtained was filtered, washed with hexane and dried under vacuum. The crude solid was redissolved in ethyl acetate, undissolved compound was separated by filtration and washed successively with ethyl acetate. Organic layer dried over anhydrous sodium sulfate and evaporated to dryness by rotary evaporator.

The crude product was further purified by flash column chromatography using dichloromefhane as eluent.

Method-II: To a stirred solution of PPIB in THF/DMF (40 vol.) under N₂ atmosphere, was charged 4-(4,6-Dimefhoxy-l ,3,5-triazin-2-yl)-4- methylmorpholin-4-ium chloride (DMTMM) (1.5 eq.) and stir for 15 min at room temperature. Reaction mixture was cooled to 10-15°C and DIPEA charged slowly. Reaction mixture was allowed to stir for overnight at room temperature and workup and purification was carried as described in method I.

[0049] Example 2: Preparation of Micafungin

To a stirred solution of FR 179642 (0.93 g 1 mmol) in DMF (10.0 mL) was charged active ester of Formula I (1.1 eq.) and DIPEA (1.5 eq.) at 5-10 °C. Reaction mixture was stirred for overnight at 25°C.

Workup: Reaction mixture was cooled to 5-10 °C and ethyl acetate (20 vol.) was charged slowly. Obtained white solid was filtered and washed successively with ethyl acetate, dried under vacuum. Solid stirred with acetonitrile (5 vol.) for 15 min. at RT and filtered. Obtained solid dried under vacuum.

[0050] Example 3: Preparation of Micafungin (Active ester in situ)

To a stirred solution PPIB (1 gm, 2.84 mmol) in THF/DMF (20 mL) under N₂ was charged CDMT (0.6 gm, 3.41 mmole) and NMM (0.480 mL, 4.26 mmol, 1.5 eq.) at 10 - 15 °C. The mixture was allowed to stir for overnight at room temperature. Upon confirmation of active ester formation by HPLC, FR 179642 (2.66 g, 2.84 mmol) and diisopropylethylamine (0.742 mL, 4.26 mmol) were added and continued stirring for 3-4 hrs at room temperature. The reaction mixture was filtered, the filtrate was cooled 5-10 °C and cold diisopropyl ether was charged slowly. The precipitated white solid was filtered and washed successively with diisopropyl ether and suck dried. Obtained solid stirred with acetonitrile (5 vol.) for 15 min. at RT and filtered and dried under vacuum.

[0051] Example 4: Preparation of Micafungin (Active ester in situ)

The reaction is carried out in an analogous manner as in example 2 using NMM as base.

[0052] Example 5: Preparation of Micafungin

To a stirred solution of PPIB (1 gm, 2.84 mmol), CDMT (0.6 gm, 3.41 mmole) and FR 179642 (2.66 g, 2.84 mmol) in DMF (20 mL) was charged NMM ( 0.96mL, 8.5 mmol, 3 eq.) at room temperature. The mixture was allowed to stir for overnight at room temperature. The reaction mixture was filtered, the filtrate was charged slowly in diisopropyl ether. The precipitated white solid was filtered and washed successively with ether and suck dried. Obtained solid stirred with acetonitrile (5 vol.) for 15 min. at RT and filtered and dried under vacuum.

[0053] Example 6 ^'

The reaction is carried out in an analogous manner as in example 4 for 3-12hrs at 40°C.

[0054] Example 7 ,

The reaction is carried out in an analogous manner as in example 4 for 3-12hrs at 60°C.

[0055] Example 8: Preparation of Micafungin

To a stirred solution of PPIB (0.374 gm, 1.07 mmol), CDPT (0.22 gm, 1.28 mmole) and FR 179642 (1 g, 1.07 mmol) in DMF (10 mL) was charged NMM ( 0.2 mL, 2.14 mmol, 2 eq.) at 0-5°C. The mixture was allowed to stir for 3-12 hrs at RT. The reaction mixture was filtered, the filtrate was charged slowly in diisopropyl ether. The precipitated white solid was filtered and washed successively with ether and suck dried. Obtained solid stirred with acetonitrile (5 vol.) for 15 min. at RT and filtered and dried under vacuum.

[0056] Example 9: Preparation of Micafungin sodium salt

To a stir solution of Micafungin in MeOH/DMF (5 vol.) was charged sodium 2- ethylhexanoate (1.1 eq.) at 5-10 °C and the mixture was stirred for 5 h at 10-15 °C. Reaction mixture was cooled to 5-10 °C and ethyl acetate (20 vol.) was charged slowly. The precipitated white solid was filtered and washed successively with ethyl acetate followed by acetone and dried under vacuum.

[0057] Example 10: Preparation of Micafungin sodium salt

The reaction is carried out in an analogous manner as in example 4 for overnight at RT.

[0058] Example 11: Preparation of Micafungin sodium salt

To stir solution of Micafungin (0.5 gm, 0.393 mmol) in MeOH 15 mL was charged aqueous solution of sodium 2-ethylhexanoate (0.079 gm, 0.472 mmol) at 0-5°C and the mixture was stirred for 16 hrs at RT. Solvent evaporated under vacuum and charged acetone 50 mL and stirred for 15 min. Precipitated white solid was filtered and washed successively with acetone and dried under vacuum.

Claims

We claim,

1. A compound of Formula I

Formula I (a) R', R" = CH₃

(b), R', " = C₍₎H_;

2. The compound according to claim 1 is selected from

Formula IA or

-

Formula IB

3. A process for preparation of compound of Formula I comprising the steps of:

a) reacting the compound of Formula (A) with compound of Formula (B) to give com ound of Formula (C).

a, . R.',R" = OCH₃

b, R\R* = OCgH₅

(A) (B) (C) where each of R_{1 }} R₂, R₃ independently is hydrogen, alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups or alternatively Ri, R₂ and R₃ together with nitrogen or any two of the Ri, R₂ and R₃ together with nitrogen atom to which they are attached form a heterocycloalkyl or heterocyclic ring which is optionally substituted with alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups, nitro, halo, amino or substituted amino groups or alternatively Ri, R₂ and R₃ together with nitrogen form a guanidine or substituted guanidine. b) reacting the compound of Formula (C) with 4-(5-(4-

(pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (PPIB) of Formula III to form a compound of Formula I

Formula I (a) R', R" = CH,

(b), R\ R" = C₆H₅

c) isolating the compound of Formula I and

d) optionally purifying the compound of Formula I.

4. A process for preparation of a compound of Formula I comprising the steps of a) reacting 4-(5-(4-(pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (PPIB) with 2-chloro-4,6-dimethoxy-l,3,5-triazine (CDMT) or 2-chloro-4,6- diphenyloxy-l ,3,5-triazine (CDPT) in presence of base and solvent to give the compound of Formula I

b) isolating the compound of Formula I and

c) Optionally purifying the compound of Formula I.

The process according to claim 5 wherein the reaction of step a) is carried out at room temperature for overnight or for 3 to 12 hour.

A process for preparation of Micafungin comprising the steps of

a) reacting 4-(5-(4-(pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (PPIB), 2-chloro-4,6-dimethoxy-l ,3,5-triazine (CDMT) or 2- chloro-4,6-diphenyloxy-l ,3,5-triazine (CDPT) in presence of a solvent to form the compound of Formula I and

b) reacting the compound of Formula I formed in step a) with the compound of Formula IV in presence of base and

c) isolating Micafungin and optionally purifying.

A process for preparation of Micafungin comprising the steps of

a) reacting 4-(5-(4-(pentyloxy)phenyl)isoxazol-3-yl)benzoic acid (PPIB), 2-chloro-4,6-dimethoxy-l ,3,5-triazihe (CDMT) or 2- chloro-4,6-diphenyloxy- l,3,5-triazine (CDPT) and the compound of Formula IV in presence of base and solvent and

FR-179642 Formula IV

b) isolating Micafungin and optionally purifying.

8. The process as claimed in claim 7 wherein the reaction of step a) is carried out for 3 to 15 hours and at temperature selected from room temperature or at 30 to 80°C.

9. A process for preparation of Micafungin comprising the steps of

d) reacting the compound of Formula IV in a solvent with the compound of Formula I in presence of a base

Formula I (a) R', R" = CH,

(b), R\ R" = C₆H₅

e) isolating Micafungin and optionally purifying and

f) optionally converting Micafungin or purified Micafungin into pharmaceutically acceptable salts.

10. The process according to any of the preceding claims, wherein said solvent is selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide, toluene, 2- methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and mixtures thereof and said base is selected from the group consisting of N- methylmorpholine, N,N, N,N-tetramethylguanidine, pyridine, N-methyl-2- pyrrolidone (NMP), triethylamine, 4-picoline, 4-dimethylaminopyridine (DMAP), toluene, N-methylpiperidine and Ν,Ν,Ν,Ν- tetramethylethylenediamine, and combination thereof.