Salts of methyl 6-(2,4-dichlorophenyl)-5-[4-[(3S)-l-(3-fluoropropyl)pyrrolidin-3-yl]oxyphenyl]-8,9-dihydro-7H-benzo[7]annulene-2-carboxylate and preparation process thereof

Abstract

Herein are provided novel salts of methyl 6-(2,4-dichlorophenyl)-5-[4-[(3S)-1-(3-fluoropropyl)pyrrolidin-3-yl]oxyphenyl]-8,9-dihydro-7H-benzo[7]annulene-2-carboxylate namely the oxalate salt ##STR00001##
and the dibenzoyltartrate salt ##STR00002##

Claims

1. An oxalate salt of 6-(2,4-dichlorophenyl)-5-{4-[1-(3-fluoro-propyl)-pyrrolidin-3-yloxy]-phenyl}-8,9-dihydro-7H-benzocycloheptene-2-carboxylic acid methyl ester of the formula below: ##STR00025##

2. A dibenzoyl tartaric salt of 6-(2,4-dichlorophenyl)-5-{4-[1-(3-fluoro-propyl)-pyrrolidin-3-yloxy]-phenyl}-8,9-dihydro-7H-benzocycloheptene-2-carboxylic acid methyl ester of the formula below: ##STR00026##

Description

EXAMPLE 1

Preparation of the Organoboron Derivative “Reagent (1)”

(1) The preparation of reagent (1), useful in the Suzuki coupling step of the process for synthesis of compound (2) as described herein, is illustrated in scheme 5 below, reproduced from the patent application WO 2017/140669.

(2) ##STR00020##

(3) According to scheme 5, the commercially available compound (a) (4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenol) is condensed in tetrahydrofuran (THF) at room temperature on (R)-1-N-Boc-3-hydroxypyrrolidine, using N,N,N′,N′-tetramethylazodicarboxamide as coupling agent.

(4) According to step 2, the compound (c) thus obtained is N-deprotected in methanol (MeOH) at room temperature using an acidic agent, for example a solution of HCl 4N in dioxane.

(5) Alkylation of the pyrrolidine nitrogen is then performed under step 3 by reacting compound (d) with the corresponding 1,1-disubstituted 1-halogeno-3-fluoro propane, for example 1-iodo-3-fluoropropane, in acetonitrile in presence of potassium carbonate (K.sub.2CO.sub.3) at about 40° C.

(6) Steps 1 to 3 of scheme 5 are illustrated by the detailed protocols below.

(7) The .sup.1H NMR spectra were performed on a Bruker Avance DRX-400 spectrometer, with the chemical shifts (δ in ppm) in the solvent dimethyl sulfoxide-d6 (dDMSO-d6) referenced at 2.50 ppm at a temperature of 303 K. Coupling constants (J) are given in Hertz.

(8) The liquid chromatography/mass spectrography (LC/MS) data were obtained on a UPLC Acquity Waters instrument, light scattering detector Sedere and SQD Waters mass spectrometer using UV detection DAD 210<1<400 nm and column Acquity UPLC CSH C18 1.7 μm, dimension 2.1×30 mm, mobile phase H.sub.2O+0.1% HCO.sub.2H/CH.sub.3CN+0.1% HCO.sub.2H.

Compound (c). Tert-butyl (3S)-3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2yl)phenoxy]pyrrolidine-1-carboxylate

(9) ##STR00021##

(10) To a solution of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenol (a) (82.7 g, 364.51 mmol) in THF (2 L) was added under argon (R)-1-N-Boc-3-hydroxypyrrolidine (b) (84.43 g, 437.41 mmol) followed by N,N,N′,N′-tetramethylazodicarboxamide (99.1 g, 546.77 mmol). The clear reaction mixture turned orange and triphenylphosphine (143.41 g, 546.77 mmol) was added. The reaction mixture was stirred at room temperature for 24 hours, meanwhile a precipitate of triphenylphosphine oxide formed (Ph.sub.3P═O). The reaction mixture was poured in water (1.5 L) and extracted with ethyl acetate (AcOEt) (3×1.5 L). Gathered organic phases were dried over magnesium sulfate (MgSO.sub.4), filtered and concentrated under reduced pressure. The residue was taken up into diisopropylether (1.5 L) and the solid formed (Ph.sub.3P═O) was filtered. The solvent was concentrated under reduced pressure and the residue purified by column chromatography eluting with a mixture of heptane with AcOEt (90/10; v/v) to give 145 g (100%) of tert-butyl (3S)-3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenoxy]pyrrolidine-1-carboxylate (c) as a colorless oil.

(11) .sup.1H NMR (400 MHz, DMSO-d6, δ ppm): 1.27 (s, 12H); 1.39 (s, 9H); 2.05 (m, 1H); 2.14 (m, 1H); 3.37 (3H); 3.55 (m, 1H); 5.05 (s, 1H); 6.94 (d, J=8.4 Hz, 2H); 7.61 (d, J=8.4 Hz, 2H).

Compound (d). (3S)-3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2yl)phenoxy]pyrrolidine, Hydrochloride

(12) ##STR00022##

(13) To a solution of (S)-tert-butyl 3-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenoxy)pyrrolidine-1-carboxylate (c) (80 g, 195.23 mmol) in MeOH (450 ml) was added slowly HCl 4N in dioxane (250 ml).

(14) After 1.5 hours, the reaction mixture was concentrated under reduced pressure and the residue was taken up into Et.sub.2O with stirring to give a solid which then was filtered and dried under vacuum to give compound (d) 61.8 g (95%) as a white powder.

(15) .sup.1H NMR (400 MHz, DMSO-d6, δ ppm): 1.28 (s: 12H); 2.10 (m: 1H); 2.21 (m: 1H); 3.31 (3H); 3.48 (m: 1H); 5.19 (m: 1H); 6.97 (d, J=8.4 Hz: 2H); 7.63 (d, J=8.4 Hz: 2H); 9.48 (s: 1H); 9.71 (s: 1H).

(16) LC/MS (m/z, MH.sup.+): 290

Reagent (1). (3S)-1-(3-fluoropropyl)-3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenoxy]pyrrolidine

(17) ##STR00023##

(18) To a suspension of (S)-3-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenoxy)pyrrolidine hydrochloride (d) (20 g, 61.42 mmol) in acetonitrile (100 ml), was added K.sub.2CO.sub.3 (21.22 g, 153.54 mmol) and 1-iodo-3-fluoropropane (12.15 g, 61.42 mmol), under argon. The reaction mixture was stirred at 40° C. for 24 hours. After cooling to room temperature, the reaction mixture was filtered and washed with acetonitrile. The filtrate was concentrated under reduced pressure and the residue was taken up in DCM and the solid formed was filtered and washed with DCM. The filtrate was concentrated to give reagent (1) 21.5 g (100%) as a yellow foam.

(19) .sup.1H NMR (400 MHz, DMSO-d6, δ ppm): 1.27 (s, 12H); 1.77 (m, 2H); 1.84 (m, 1H); 2.27 (m, 1H); 2.41 (m, 1H); 2.49 (2H); 2.62 (dd, J=2.6 and 10.4 Hz, 1H); 2.69 (m, 1H); 2.83 (dd, J=6.2 and 1.4 Hz, 1H); 4.47 (td, J=6.2 and 47 Hz, 2H); 4.99 (m, 1H); 6.77 (d, J=8.4 Hz, 2H); 7.58 (d, J=8.4 Hz, 2H).

(20) LC/MS (m/z, MH.sup.+): 350

EXAMPLE 2

Synthesis of Compound (2) from Carboxymethoxy-Benzosuberone (5)

(21) The numbering of the intermediate and final compounds (2), (3′), (4) and (5) refer to scheme 2 described before.

(22) In the first step S1, the 5-oxo-6,7,8,9-tetrahydrobenzo[7]annulene core of compound (5) (carboxymethoxybenzosuberone) is arylated at the 6-position via a palladium catalyzed coupling of 1-bromo-2,4-dichloro-benzene in refluxing toluene and in the presence of potassium carbonate, to yield the 2,4-dichlorophenyl precursor (4) isolated as a Me-THF solution after silica gel filtration.

(23) In the second step S2, the crude Me-THF solution of compound (4) is reacted with N-phenyl-bis-triflimide in the presence of catalytic DBU and an excess of sodium hydride. After water washing and solvent exchange to acetonitrile, the desired triflated compound (3′) is isolated by crystallization as a white solid.

(24) In a third step S3, the cyclic enol triflate (3′) is coupled to the chiral boronic ester “reagent (1)” as described earlier via a palladium catalyzed Suzuki reaction performed in an acetonitrile/water mixture at 40±3° C., using cesium carbonate as a base. After aqueous work-up and solvent exchange with isopropylacetate, residual palladium is eliminated by sequential ethylenediamine, charcoal and dimercaptotriazine grafted silica treatments. The crude oxalate salt of compound (2) is isolated by crystallization in isopropylacetate.

(25) These steps are illustrated by the detailed protocols below.

(26) The .sup.1H NMR spectra were performed on a 300 or 400 MHz Bruker Avance spectrometer, with the chemical shifts (δ in ppm) in the solvent dimethyl sulfoxide-d6 (dDMSO-d6) referenced at 2.50 ppm at a temperature of 303 K. Coupling constants (J) are given in Hertz.

(27) The liquid chromatography/mass spectrography (LC/MS) data were obtained on a UPLC-SQD Waters instrument, evaporating light scattering detector Sedere and SQD Waters mass spectrometer using UV detection DAD 210<1<400 nm and column Acquity UPLC CSH C18 1.7 μm, dimension 2.1×50 mm, mobile phase H.sub.2O+0.1% HCO.sub.2H/CH.sub.3CN+0.1% HCO.sub.2H.

2.1: Steps S1 and S2 Concatenated

(28) A degassed mixture of methyl 5-oxo-6,7,8,9-tetrahydro-5H-benzo[7]annulene-2-carboxylate (5) (40 g), potassium carbonate (K.sub.2CO.sub.3, 40 to 101 g i.e. 1.5 to 4 eq.), bromo-dichlorobenzene (62.1 g), Xantphos (21.2 g) and Pd.sub.2dba.sub.3 (8.39 g) is refluxed in toluene (320 ml) under nitrogen and vigorous stirring until completion.

(29) After cooling to room temperature, insoluble material is eliminated by filtration on a pad of silica (80 g), followed by washings of the filter with toluene (600 ml). Toluene is distilled off from the filtrate and exchanged with Me-THF to yield a solution of the α-arylation product (4) (methyl 6-(2,4-dichlorophenyl)-5-oxo-6,7,8,9-tetrahydrobenzo[7]annulene-2-carboxylate) in MeTHF (400 ml), used as is in the next step.

(30) A sample of pure product (4) has been isolated by silica gel chromatography of an aliquot (eluent: dichloromethane-heptane).

(31) .sup.1H NMR (400 MHz, DMSO-d6 in ppm) of the isolated compound (4): 1.77 (m, 1H) 2.00 (m, 1H); 2.18 (m, 2H); 3.08 (m, 1H); 3.20 (m, 1H); 3.89 (s, 3H); 4.46 (dd, J=11.3, 3.7 Hz, 1H); 7.46 (m, 2H); 7.59 (d, J=2.0 Hz, 1H); 7.64 (d, J=7.9 Hz, 1H); 7.91 (dd, J=8.0, 1.4 Hz, 1H); 7.94 (s, 1H).

(32) LC/MS ([M+H].sup.+): 363

(33) To the Me-THF solution of compound (4) obtained in step S1 (scale: 40 g of compound (4)) is added N,N-bis(trifluoromethylsulfonyl)aniline (80 g). The resulting solution is added dropwise at 0° C., under stirring, to a Me-THF (200 ml) suspension of NaH (10 g—60% dispersion in oil) containing DBU (5 ml). The reaction mixture is stirred at room temperature until completion.

(34) After cooling to 0° C., acetic acid (4 ml), followed by water (400 ml), are added dropwise. The aqueous phase is separated at room temperature and the organic phase is washed with diluted aqueous sodium chloride (NaCl, 0.6 M; 3×400 ml). Me-THF is distilled off and exchanged with acetonitrile. After elimination of insoluble material by filtration in hot acetonitrile, compound (3′) (methyl 6-(2,4-dichlorophenyl)-5-(trifluoromethylsulfonyloxy)-8,9-dihydro-7H-benzo[7]annulene-2-carboxylate) is crystallized in 250 ml of acetonitrile, isolated by filtration and washings with cold acetonitrile and heptane, to yield 61.2 g of pure triflate as a white solid.

(35) Yield: 67.4% (in 2 steps S1 and S2).

(36) .sup.1H NMR (400 MHz, DMSO-d6 in ppm): 2.18 (m, 2H); 2.41 (m, 2H); 2.95 (m, 2H); 3.90 (s, 3H); 7.55 (m, 2H); 7.68 (d, J=8 Hz, 1H); 7.80 (d, J=1.8 Hz, 1H) 8.01 (m, 2H).

(37) LC/MS (EI m/z): 494.sup.+

(38) Purity of compound (3′): 99.0%, measured by HPLC: Mobile phase: water/acetonitrile/HCOOH; Stationary phase: XSelect CSH C18-3.5 μm (Waters) or equivalent; Column length: 100 mm; Column internal diameter: 4.6 mm; Flow rate: 1 mL/minute; Injection volume: 10 μL; Detection: 254 nm (UV).

2.2: Step S3

(39) A degassed mixture of the triflate (3′) (20 g), the boronic ester “reagent (1)” (14.1 g), Cs.sub.2CO.sub.3 (19.7 g), bis(triphenylphosphine) palladium(II)dichloride (1.4 g), water (100 ml) and acetonitrile (260 ml), is stirred at 40° C. under nitrogen. After complete conversion, the reaction medium is cooled to room temperature, isopropylacetate (100 ml) is added and the aqueous phase is separated. The organic phase is washed with diluted aqueous NaCl (0.3 M; 2×200 ml), dried by azeotropic distillation of isopropylacetate and treated subsequently with ethylenediamine, charcoal and dimercaptotriazine grafted silica, to remove residual palladium.

(40) The resulting solution of compound (2), namely 6-(2,4-dichlorophenyl)-5-{4-[1-(3-fluoro-propyl)-pyrrolidin-3-yloxy]-phenyl}-8,9-dihydro-7H-benzocycloheptene-2-carboxylic acid methyl ester, in isopropylacetate, adjusted at 200 ml, is heated to 70° C. and an oxalic acid (3.6 g) solution in isopropylacetate (43 ml) is added dropwise under stirring. After seeding (using seeds previously prepared on another batch of product by conventional crystallisation techniques) and cooling to 0° C., the desired oxalate salt of compound (2), depicted below, crystallizes and is isolated by filtration in a 70% yield (18.6 g, white powder):

(41) ##STR00024##

(42) .sup.1H NMR (400 MHz, DMSO-d6 in ppm): 7.92 (d, J=2.0 Hz, 1H); 7.78 (dd, J=8.0 and 2.0 Hz, 1H); 7.59 (d, J=2.2 Hz, 1H); 7.29 (dd, J=8.3 and 2.2 Hz, 1H); 7.22 (d, J=8.3 Hz, 1H); 6.90 (d, J=8.0 Hz, 1H); 6.78 (d, J=9.0 Hz, 2H); 6.73 (d, J=9.0 Hz, 2H); 4.98 (m, 1H); 4.50 (dt, J=47.2 and 5.7 Hz, 2H); 3.86 (s, 3H); 3.49 (dd, J=12.8 and 5.8 Hz, 1H); from 3.38 to 3.08 (m, 5H); 2.94 (t, J=5.0 Hz, 2H); 2.34 (m, 1H); from 2.23 to 2.11 (m, 3H); from 2.07 to 1.93 (m, 2H).

(43) LC/MS ([M+H].sup.+): 568

(44) Purity of compound (2), oxalate salt: 98.2%, measured by HPLC under the same conditions as described in step S2 above.

EXAMPLE 3

Alternative Protocols for Step S1

3.1: Alternative 1

(45) A 2 M THF solution of sodium tert-butoxide (19.48 ml) is added dropwise at 60° C. to a degassed mixture containing compound (5) (5 g), 1-bromo-2,4-dichlorobenzene (7.76 g), palladium acetate (257 mg), Xantphos (660 mg) and THF (20 ml). The reaction is heated at 60° C. until completion, cooled to room temperature, quenched with molar aqueous KH.sub.2PO.sub.4. After ethyl acetate extraction, water washings and purification by silica gel chromatography, compound (4) is isolated in a 70% yield and 92% purity.

(46) .sup.1H NMR (400 MHz, DMSO-d6 in ppm): 1.78 (m, 1H); 2.01 (m, 1H); 2.19 (m, 2H); 3.10 (m, 1H); 3.22 (m, 1H); 3.89 (s, 3H); 4.47 (dd, J=11.3, 3.6 Hz, 1H); 7.47 (m, 2H); 7.61 (d, J=1.8 Hz, 1H); 7.65 (d, J=7.9 Hz, 1H); 7.92 (d, J=7.7 Hz, 1H); 7.95 (s, 1H).

(47) LC/MS ([M+H].sup.+): 363

3.2: Alternative 2

(48) A degassed mixture containing compound (5) (0.5 g), 1-iodo-2,4-dichlorobenzene (0.76 ml), toluene (9 ml), water (1 ml), Cs.sub.2CO.sub.3 (1.05 g), palladium acetate (50 mg) and Xantphos (250 mg) is heated to reflux during about 22 hours. After cooling to room temperature, the organic phase is diluted with dichloromethane, washed with water and purified by chromatography on silica gel to yield 730 mg (87%) of a white solid.

(49) .sup.1H NMR (400 MHz, DMSO-d6 in ppm): 1.78 (m, 1H); 2.01 (m, 1H); 2.19 (m, 2H); 3.09 (m, 1H); 3.21 (m, 1H); 3.89 (s, 3H); 4.47 (dd, J=11.3, 3.7 Hz, 1H); 7.47 (m, 2H); 7.60 (d, J=2.0 Hz, 1H); 7.64 (d, J=8.1 Hz, 1H); 7.92 (dd, J=7.9, 1.5 Hz, 1H); 7.95 (s, 1H).

EXAMPLE 4

Alternative Protocols for Step S2

(50) 3.1: Alternative 1

(51) A 0.5 M THF solution of potassium bis-trimethylsilylamide (7.70 ml) is added dropwise at −50° C. to a mixture of compound (4) (1 g) and N-phenylbis-triflimide (1.22 g) in THF (18 ml). After warming up to room temperature, the reaction medium is quenched with water at 0-5° C., extracted with dichloromethane followed by ethyl acetate, and purified by silica gel chromatography (eluent: dichloromethane-heptane) to afford the desired compound (3′) in an 80% yield and 90% purity measured by LC/MS.

(52) .sup.1H NMR (400 MHz, DMSO-d6 in ppm): 2.18 (m, 2H); 2.41 (m, 2H); 2.95 (m, 2H); 3.89 (s, 3H); 7.55 (m, 2H); 7.68 (d, J=8.1 Hz, 1H); 7.80 (d, J=1.7 Hz, 1H); 8.01 (m, 2H).

(53) LC/MS ([M+H].sup.+): 494

3.2: Alternative 2

(54) DBU (247 μl) is added dropwise at 0-5° C. to a suspension containing compound (4) (500 mg), and N,N-bis(trifluoromethylsulfonyl)aniline (639 mg) in acetonitrile (2 ml). The conversion rate is about 80% after stirring 22 hours at room temperature. The reaction mixture is cooled down to 0-5° C. and sodium hydride (27.5 mg of a 60% dispersion in oil) is added. After 1.5 hours stirring at room temperature, the conversion rate is about 100%. The resulting suspension is cooled down to 0-5° C., filtrated and washed with pre-cooled acetonitrile (0.5 ml) followed by water (2 ml) to yield 460 mg of compound (3′) as a white powder (yield: 67.5%) with a purity of 98% measured by LC/MS.

(55) .sup.1H NMR (400 MHz, DMSO-d6 in ppm): 2.18 (m, 2H); 2.42 (m, 2H); 2.95 (m, 2H); 3.90 (s, 3H); 7.55 (m, 2H); 7.68 (d, J=7.9 Hz, 1H); 7.82 (s, 1H); 8.02 (m, 2H).

(56) As shown in the above examples, the process of synthesis for salts of compound (2) described herein allows a global yield, from compound (5) to compound (2), of about 33 to 49%. This is a greater yield than the one found in the previously described process of synthesis as set forth in scheme 3, wherein the yield for obtaining compound (2) is about 26% when starting from the same compound methyl 5-oxo-6,7,8,9-tetrahydro-5H-benzo[7]annulene-2-carboxylate.

(57) Also, the process of synthesis described herein allows to obtain compound (2) in novel salt forms in a good yield without the need to perform column chromatographies after the Suzuki coupling step, which was needed in the syntheses routes previously known involving base form of compound (2), but which is not appropriate when seeking a synthesis route applicable at the industrial level.

EXAMPLE 5

Synthesis of Compound (2) in the Form of a Dibenzoyl Tartrate Salt

(58) A degassed mixture of methyl 8-bromo-9-(4-{[(3S)-1-(3-fluoropropyl)pyrrolidin-3-yl]oxy}phenyl)-6,7-dihydro-5H-benzo[7]annulene-3-carboxylate hydrobromide (25.0 g), 2,4-dichlorophenylboronic acid (9.9 g), K.sub.2CO.sub.3 (11.9 g), bis(triphenylphosphine) palladium(II)dichloride (1.4 g), water (75 ml) and 1,4-dioxane (206 ml), is stirred at 60° C. under nitrogen. Then 2,4-dichlorophenylboronic acid (9.9 g) is solubilized in a mixture of water and 1,4-dioxane (25 ml) and added. After complete conversion, the reaction medium is cooled to room temperature, and pyrrolidinedithiocarbamate (1.4 g) in water (50 ml) is added. The mixture is stirred at 20° C. and filtered. The filter is washed with toluene and the aqueous phase is separated. The organic phase is washed with diluted aqueous NaCl (2 M, 3×75 ml). Then charcoal (2.5 g) and Al.sub.2O.sub.3 (50.1 g) are added at 20° C. The mixture is filtered and the filter is washed with toluene (3×50 ml). The organic phase is concentrated to 1.8 volumes in order to remove a part of 1,4-dioxane.

(59) (−)dibenzoyltartaric acid (15.4 g) is added to the resulting solution of compound (2), namely 6-(2,4-dichlorophenyl)-5-{4-[1-(3-fluoro-propyl)-pyrrolidin-3-yloxy]-phenyl}-8,9-dihydro-7H-benzocycloheptene-2-carboxylic acid methyl ester. N-heptane (300 ml) is added dropwise under stirring at 20° C. The dibenzoyltartaric salt of compound (2) is isolated by filtration in a 85% yield (43.3 g).

(60) RMN .sup.1H (400 MHz, DMSO-d.sub.6 in ppm): 1.82-1.98 (m, 3H); 2.09-2.30 (m, 5H); 2.89-3.22 (m, 7H); 3.39 (m, 1H); 3.86 (s, 3H); 4.39 (td, J=5.9 and 47.4 Hz, 2H); 4.87 (m, 1H); 5.76 (s, 2H); 6.67 (d, J=8.9 Hz, 2H); 6.75 (d, J=8.9 Hz, 2H); 6.90 (d, J=8.1 Hz, 1H); 7.20 (d, J=8.4 Hz, 1H); 7.29 (dd, J=2.0 and 8.4 Hz, 1H); 7.54 (t, J=7.9 Hz, 4H); 7.60 (d, J=2.0 Hz, 1H); 7.68 (tt, J=1.3 and 7.9 Hz, 2H); 7.79 (dd, J=1.8 and 8.1 Hz, 1H); 7.96 (d, J=1.8 Hz, 1H); 7.98 (t, J=7.9 Hz, 4H); 10.70 (m spread, 1H); 13.00 (m spread, 1H).

(61) The liquid chromatography/mass spectrography (LC/MS) data were obtained as follows:

(62) Analytical Data in Mass Spectrometry

(63) M.sup.+=568 g.Math.mol−1

(64) M′ (salt)=358 g.Math.mol−1

(65) Mass spectrometer: Waters UPLC-SQD, electrospray ionization (ES+/−) Chromatographic conditions: Column: ACQUITY UPLC CSH C18-1.7 μm-2.1×50 mm Solvents: A: H.sub.2O (+0.1% formic acid) B: CH3CN (+0.1% formic acid) Column temperature: 45° C. Rate: 0.85 ml/min Gradient (2.5 min): from 5 to 100% of B in 2.5 min; 2.40 min 100% B; from 100 to 5% of B in 0.05 min

(66) UV: from 190 to 380 nm

(67) Results:

(68) at 1.12 min (31% in UV purity): m/z=357 in ES− corresponding to [M′−H].sup.−

(69) at 1.17 min (67% in UV purity): m/z=568 in ES+ corresponding to [M].sup.+

(70) Purity of Compound (2), Dibenzoyltartaric Salt: 93.2%, Measured by HPLC.

EXAMPLE 6

Salification Studies for Compound (2)

(71) The oxalate and dibenzoyl tartrate salts of compound (2) are particularly advantageous in that they precipitate and crystalize from the reaction medium, allowing to recover salts of compound (2) from the reaction medium. The base form of compound (2) did not allow to isolate the product from the reaction medium, whatever the solvents and temperatures tested. Amongst a variety of salts tested with compound (2), the oxalate and dibenzoyl tartrate salts were the only ones to allow a frank precipitation, as shown in table 1 below.

(72) TABLE-US-00001 TABLE 1 salification studies for compound (2) used at a scale of 0.25 g of the base form and at a temperature of 20° C. Solvent (5 volumes) Acid (1 eq.) Visual observations Toluene Dibenzoyl tartaric acid Precipitates with heptane MIBK (methyl- Dibenzoyl tartaric acid No precipitation isobutyl-ketone) MTBE (methyl- Dibenzoyl tartaric acid No precipitation tertbutyl-ether) Heptane Dibenzoyl tartaric acid No precipitation Ethyl acetate Dibenzoyl tartaric acid No precipitation Ethyl acetate Sulfuric acid No precipitation Toluene Sulfuric acid No precipitation Ethyl acetate Glyoxylic acid No precipitation Toluene Glyoxylic acid Slight precipitation Ethyl acetate Trifluoromethanesulfonic No precipitation acid Toluene Trifluoromethanesulfonic No precipitation acid Ethyl acetate Formic acid Slight precipitation Toluene Formic acid Precipitation, followed by gum formation Ethyl acetate Trifluoroacetic acid Slight precipitation Toluene Trifluoroacetic acid No precipitation Ethyl acetate Phosphomolybdic acid No precipitation Toluene Phosphomolybdic acid No precipitation Ethyl acetate Lactic acid No precipitation Toluene Lactic acid Slight precipitation Ethyl acetate Isethionic acid (0.5N in Slight precipitation water) Toluene Isethionic acid (0.5N in Slight precipitation water) Toluene Succinic acid No precipitation Toluene Citric acid No precipitation Toluene Fumaric acid Slight precipitation Toluene Stearic acid Slight precipitation Toluene Oxalic acid Precipitates MIBK Oxalic acid No precipitation MTBE Oxalic acid Precipitates Acetonitrile Oxalic acid No precipitation Ethanol Oxalic acid No precipitation Ethyl acetate Oxalic acid Precipitates Isopropyl Tartaric acid No precipitation alcohol MIBK Tartaric acid Precipitates, but few product, which is hygroscopic Acetonitrile Tartaric acid No precipitation MIBK Methanesulfonic acid No precipitation Toluene Naphtalene-sulfonic acid No precipitation MIBK Naphtalene-sulfonic acid No precipitation MTBE Naphtalene-sulfonic acid No precipitation Ethyl acetate Naphtalene-sulfonic acid No precipitation Heptane Naphtalene-sulfonic acid No precipitation Toluene Naphtalene-disulfonic acid No precipitation MIBK Naphtalene-disulfonic acid No precipitation MTBE Naphtalene-disulfonic acid No precipitation Ethyl acetate Naphtalene-disulfonic acid No precipitation Heptane Naphtalene-disulfonic acid No precipitation