FIELD OF THE INVENTION

The present invention relates to a route of synthesis of ceftaroline or ceftaroline fosamil, and to some of the intermediates of this synthesis. One intermediate specific for this synthesis is a novel crystalline toluene hemi-solvate form of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate of formula I. The present invention also relates to a process for the preparation of crystalline toluene hemi-solvate form of benzhydryl (6R,7R)- 7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthio]-3-cep hem-4-carboxylate, and its use for the preparation of cephalosporin derivatives.

Formula I

Another intermediate specific for this synthesis is 4-[2-[[(6R,7R)-7-amino-2 carboxy-8-oxo-5- thia-l-azabicyclo[4.2.0]oct-2-en-3-yl]-thio]-4-thiazolyl]-l- methyl-pyridinium chloride, hydrochloride of formula V. The present invention also relates to at least one process for the preparation of said intermediates, and their use for the preparation of cephalosporin derivatives.

BACKGROUND OF THE INVENTION

The cephalosporins are a class of β-lactam antibiotics originally derived from the fungus Cephalosporium acremonium. Cephalosporins, as well as cephamycins, are based upon the cephem nucleus 5-thia-l-azabicyclo[4.2.0]oct-2-en-8-on, which is why the group of

cephamycins and cephaolosporins is sometimes referred to as cephems.

The core of all cephalosporins is illustrated below:

Cephalosporins are indicated for the prophylaxis and treatment of infections caused by bacteria susceptible to this particular form of antibiotic. First-generation cephalosporins are active predominantly against Gram-positive bacteria, and successive generations have increased activity against Gram-negative bacteria (albeit often with reduced activity against Gram-positive organisms).

One of the key intermediates of the synthesis of cephalosporin derivatives such as ceftaroline, is benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem-4- carboxylate.

Formula II

EP1310502 Bl discloses benzhydryl (6R,7R)-7p-[(phenylacetyl)amino]-3-[4-pyridyl-2- thiazolylthio]-3-cephem-4-carboxylate in a crystalline form, which is believed to be the acetic acid solvate. The patent also discloses a process for the preparation of benzhydryl (6R,7R)-7P- [(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthio]-3-cephem -4-carboxylate, in its ethyl acetate solvate form, by the treatment of 4-(4-pyridyl)-l,3-thiazole-2-thiol sodium salt with benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[(methylsulfonyl)oxy]-3-c ephem-4-carboxylate in THF at 0°C for 2 h, followed by the extraction with ethyl acetate. EP1310502 Bl does not disclose any characteristic data to specify this crystalline form. Ishikawa T. et al. (2003), discloses TAK-599, a novel N-phosphono prodrug of anti-methicillin- resistant Staphylococcus aureus (MRSA) cephalosporin (Bioorganic & Medicinal Chemistry 1 1 (11), p 2427-2437). In this article a synthesis of benzhydryl (6R,7R)-7P-[(phenylacetyl)-amino]- 3-[4-pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate is disclosed, which involves the treatment of 4-(4-Pyridyl)- 1 ,3-thiazole-2-thiol sodium salt with benzhydryl (6R,7R)-7P-[(phenylacetyl)- amino]-3-[(methylsulfonyl)oxy]-3-cephem-4-carboxylate in THF, acetic acid and methanol.

CN 102977124 discloses a process for preparation of benzhydryl (6R,7R)-7 - [(phenylacetyl)amino]-3-[4-(l-methyl-4-pyridinium)-2-thiazol ylthio]-3-cephem-4-carboxylate. The process comprises a reaction of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-hydroxy-3- cephem-4-carboxylate with methylsulfonyl chloride to obtain the corresponding sulfonate, followed by substitution with 4-(4-Pyridyl)-l ,3-thiazole-2-thiol sodium salt in DMF and N- methylation to generate the benzhydryl (6R,7R)-7-[(phenylacetyl)amino]-3-[4-(l-methyl-4- pyridyl)-2-thiazolylthio]-3-cephem-4-carboxylate.

The processes reported in EP1310502B1 for formation of a crystalline form of benzhydryl (6R,7R)-7 -[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthio]-3-cephe m-4-carboxylate is not industrially viable because it results in very low yield, and leads to a severe degradation and unsuccessful isolation of the desired product. When the inventors repeated the process described in the reference examples 9 and 10 of EP1310502B1 it was observed that stirring became nearly impossible when trying to concentrate the slurry, because of the stickiness of the residue at low volumes. Further crystallization resulted in partial formation of gummy precipitate. In summary, applying, the disclosed processes results in products of such a low quality, that comparative stability testing was impossible. Either the yield or the stability of the crystalline form or both was so poor, that no reasonable amount of product could be provided.

Thus, there is still a need for a new solvate, and a new crystalline form of benzhydryl (6R,7R)- 7P-[(phenylacetyl)-amino]-3-[4-pyridyl-2-thiazolylthio]-3-ce phem-4-carboxylate, that overcomes the above limitations, in particular with regard to yield, purity, uniformity and long term stability.

Accordingly, it is an object of the present invention to provide such a solvate, and its crystalline form of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem- 4-carboxylate, as well as a corresponding method for its preparation, and method of use for such solvate.

Therefore the present invention provides a toluene hemi-solvate of benzhydryl (6R,7R)-7 - [(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthio]-3-cephem -4-carboxylate, preferably in its crystallized form, having high purity, which is stable at room temperature (RT, which is a temperature in the range of 20°C to 30°C) and remains stable even after storage for 11 months (at RT); and a process for preparation of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate as a crystalline hemi-solvate with toluene.

The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate has improved characteristics related to its crystallinity that affects positively the isolation procedures, its purity and the stability of the obtained product.

The present invention further provides for the intermediate 4-[2-[[(6R,7R)-7-amino-2 carboxy-8- oxo-5 -thia- 1 -azabicyclo [4.2.0] oct-2-en-3-yl] -thio] -4-thiazolyl] - 1 -methyl-pyridinium chloride, hydrochloride (1 : 1 : 1) of formula V and a method for its preparation, as well as its use for the synthesis of cephems, such as for example for ceftaroline or ceftaroline fosamil.

SUMMARY OF THE INVENTION

In the first aspect, there is provided a toluene hemi-solvate of benzhydryl (6R,7R)-7P- [(phenylacetyl)amino]-3-[4- ridyl-2-thiazolylthio]-3-cephem-4-carboxylate of formula I.

Formula I In the second aspect, there is provided a crystalline form of toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem-4-carboxylate of formula I.

This crystalline form is obtained as a powder, which filters considerably faster than polymorphic forms of benzhydryl (6R,7R)-7B-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem- 4-carboxylates known so far.

In the third aspect, there is provided a process for preparing the toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem-4- carboxylate of formula I,

comprising the steps of:

a. treating the compound of formula II

Formula II with toluene at a temperature between 20 and 80 °C to form a suspension;

cooling the suspension to a temperature of from -5 to 10 °C to form crystals of compound of formula I; and

isolating the compound of formula I.

In the fourth aspect there is provided a process of preparation of a compound of formula I comprising;

a. treating a compound of formula III

Formula III

with a compound of formula IV or its salt or reactive derivative,

Formula IV

in a solvent to obtain a reaction mass;

b. treating the reaction mass with toluene at a temperature between 20 and 80 °C to form suspension;

c. cooling the suspension from -5 to 10 °C to form crystals of compound of formula I; and d. isolating the compound of formula I.

Yet another aspect of the present invention is to convert the compound of formula I to a cephalosporin derivative and/or a pharmaceutically acceptable salt, such as ceftaroline.

A further aspect of the present invention is a process of synthesizing ceftaroline or ceftaroline fosamil comprising the use of the toluene hemi-solvate of benzhydryl 7B-[(phenylacetyl)-amino]

3-[4-pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate.

Yet another aspect of the present invention, is a pharmaceutical composition comprising the toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2- thiazolylthio]-3-cephem-4-carboxylate. In another aspect, there is provided a crystalline form of 4-[2-[[(6R,7R)-7-amino-2-carboxy-8- oxo-5 -thia- 1 -azabicyclo [4.2.0] oct-2-en-3-yl] -thio] -4-thiazolyl] - 1 -methyl-pyridininium chloride, hydrochloride ( 1 : 1 : 1 ) of formula V.

Formula V

This substance is preferably provided in its crystalline form, in high purity and preferably free from ammonium chloride. Such a composition can be achieved by the specific synthetic steps as provided herein below.

Accordingly, another aspect of the present invention is the synthesis of 4-[2-[[(6R,7R)-7-amino- 2-carboxy-8-oxo-5-thia-l-azabicyclo-[4.2.0]-oct-2-en-3-yl]-t hio]-4-thiazolyl]-l-methyl- pyridinium chloride hydrochloride (1 : 1 : 1) of formula V. The process for preparing the substance of formula V from a substance of formula I is performed as a telescope synthesis, meaning that no isolation of the intermediate products takes place. It comprises the steps of:

a. treating the compound of formula I

Formula I

with methyl-p-toluenesulfonate to form 4-[2-[[(6R,7R)-2-[(diphenylmethoxy)carbonyl]- 8-oxo-7-[2-phenylacetyl)amino]-5-thia-l-azabicyclo-[4.2.0]-o ct-2-en-3-yl]-thio]-4- thiazolyl]- 1 -methyl-pyridinium, 4-methylbenzenesulfonate;

b. deprotecting the obtained substance, preferably in presence of phosphorous pentachloride, pyridine and alcohol, preferably iso-butanol, to form 4-[2-[[(6R,7R)-7- amino-2-[(diphenylmethoxy)carbonyl]-8-oxo-5-thia-l-azabicycl o[4.2.0]oct-2-en-3-yl]- thio]-4-thiazolyl]-l-methyl-pyridinium chloride, hydrochloride;

c. treating the obtained substance with an acid, preferably with concentrated hydrochloric acid, to form the compound of formula V as a crystalline solid, preferably in absence of acetonitrile.

The compound of formula V, preferably in its crystalline form, obtained by these synthesis steps is achieved at a higher purity and at higher stability, as well as with more consistent and higher yields than the product obtained by the synthesis disclosed in the art, for example in EP1310502.

Importantly, by avoiding the use of acetonitrile in step c) a substance can be obtained which is free from inclusion products containing ammonium chloride which is advantageous in the synthesis of cephems, such as ceftarolin or ceftarolin fosamil. It makes the process to produce ceftaroline or ceftaroline fosamil significantly safer.

Another aspect of the invention is therefore the compound of formula V that is free from ammonium chloride or from ammonium chloride inclusion complexes, obtained by the process described above.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1 represents the X-ray (powder) diffraction pattern of the toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem-4- carboxylate.

Figure 2 represents the Differential Scanning Calorimetry (DSC) analysis for the toluene hemi- solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3- cephem-4-carboxylate.

Figure 3 represents the Thermogravimetric Analysis (TGA) for the toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem-4- carboxylate.

Figure 4 represents the 1H NMR Spectrum for the toluene hemi-solvate of benzhydryl (6R,7R)- 7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthio]-3-cep hem-4-carboxylate.

13

Figure 5 represents the C NMR Spectrum for the toluene hemi-solvate of benzhydryl (6R,7R)- 7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthio]-3-cep hem-4-carboxylate. Figure 6 represents the IR Spectrum of the toluene hemi-solvate of benzhydryl (6R,7R)-7P- [(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthio]-3-cephem -4-carboxylate.

Figure 7 represents the three X-ray (powder) diffraction patterns of three samples of a compound according to formula V. The bottom positioned trace represents the compound obtained by the reaction described in Example 4, the middle positioned trace represents the compound obtained by the reactions described in Reference Example 4, and the top positioned trace represents the compound obtained by the reactions described in Reference Example 5.

DETAILED DESCRIPTION OF THE INVENTION The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate of formula I, which may also be referred to as benzhydryl-(6R,7R)-8-oxo-7-[(2-phenylacetyl)amino]-3-[4-(4-p yridyl)thiazol-2-yl]sulfanyl-5- thia-l-azabicyclo-[4.2.0]oct-2-ene-2-carboxylate, is an intermediate, which can be used for the preparation of another cephalosporin compound.

Formula I

The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate according to the invention is characterized by a X-ray diffraction pattern having peaks at 6.09, 7.24, 1 1.42 and 17.91 ±0.2 degrees two-theta.

The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate according to the invention is preferably characterized by a X-ray diffraction pattern having peaks at 16.40, 18.88, 20.66, 21.33, 21.81, 22.30 and 23.54±0.2 degrees two-theta. More preferably the crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-

[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthio]-3-cep hem-4-carboxylate is characterized by a X-ray powder diffraction pattern having peaks at 6.09, 7.24, 1 1.42, 16.40, 17.91 , 18.88, 20.66, 21.33, 21.81, 22.30 and 23.54±0.2 degrees two-theta.

The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate according to the invention, is most preferably characterized by a X-ray powder diffraction (XPRD) pattern having peaks at 6.09, 6.91 , 7.24, 9.69, 1 1.42, 12.60, 13.04, 14.44, 15.17, 15.98, 16.40, 16.94, 17.57, 17.90, 18.26, 18.88, 19.31 , 19.96, 20.26, 20.66, 21.33, 21.81 , 22.30, 23.46, 23.54, 23.99, 24.30, 24.86, 25.29, 26.33, 26.63, 26.88, 28.17, 28.55, 30.22, 30.89, 31.81, 33.53, 34.56, 37.03, 38.32 and 39.38 ±0.2 degrees two- theta as depicted in FIG. 1. The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate according to the invention, is preferably further characterized by its DSC curve having endothermic peak at about 104-106 °C, depicted in FIG.2.

The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate according to the invention, may be further characterized by its TGA curve corresponding to a weight loss of about 4.54 % w/w, depicted in FIG.3.

The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate according to the invention, may be further characterized by its ^! H NMR (D ⁶ -DMSO) spectrum with peaks at 2.29, 3.54, 3.68, 3.93, 5.30, 5.87, 6.98, 7.16-7.38, 7.89, 8.54, 8.60 and 9.28 ppm, depicted in FIG.4.

The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate according to the invention, may be further characterized by its ¹³ C NMR (D ⁶ -DMSO) spectrum with peaks at 20.99, 29.34, 40.13, 41.56, 58.41, 59.59, 79.24, 1 18.47, 120.20, 121.55, 125.26, 126.47-140.12, 150.36, 125.86, 160.41, 161.23, 164.77, 170.92 ppm, depicted in FIG.5.

The crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate according to the invention, may be further characterized by its IR spectrum (KBr) with peaks at 3280 ( H), 3034 (CH-aromatic), 2960,(CH-aliphatic), 1791 (b-Lactum C=0), 1702 (Ester C=0), 1654 (Amide C=0), 1535 (Pyridine C=N) and 1011 cm-1 (C-O), depicted in FIG.6.

The present invention also provides a process for the preparation of toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem-4- carboxylate of formula I, preferably the crystalline form thereof.

In this process, the compound f formula II

Formula II is treated with toluene at a temperature between 20 and 80°C, preferably at a temperature of 25- 30°C to form a suspension. In a next step the suspension thus obtained is cooled to a temperature from -5 to 10 °C, more preferably from 0 to 5°C, to form crystals of the compound of formula I.

The crystals of toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate are isolated by any of filtration, centrifugation, precipitation and other common isolation techniques, preferably by filtering.

The fourth aspect of the invention, is the process of preparation of a compound of formula I comprising the steps of a) treating a compound of formula III with a compound of formula IV or its salt or reactive derivative, in a solvent to obtain a reaction mass; b) treating the reaction mass with toluene at a temperature between 20 and 80°C to form a suspension; c) cooling the suspension down to from -5 to 10°C to form crystals of compound of formula I; and d) isolating the compound of formula I.

The solvent is selected from the group comprising hydrocarbons, such as for example toluene; esters, such as for example ethyl acetate; ketones, such as for example acetone; halogenated hydrocarbons, such as for example chloroform and dichloromethane; ethers, such as for example diethyl ether, tetrahydrofuran and dioxane; nitriles, such as for example acetonitrile; alcohols, such as for example methanol, ethanol and n-propanol; amides, such as for example

dimethylformamide and dimethylacetamide; and sulfoxides, such as for example dimethyl sulfoxide. According to the invention it is preferred that the solvent is selected from the group consisting of tetrahydrofuran, acetonitrile and methanol; most preferably the solvent is tetrahydrofuran.

The reaction temperature at step a) is from -20°C to 50°C, preferably from -5°C to 30 °C, most preferably from -2°C to 0°C. The reaction time is from 5 min to 8 h, preferably from 30 min to 8 h and more preferably from 30 min to 3.5 h, and most preferably 2h +/- 20 min. Preferably the reaction mass is then diluted with ethylacetate and washed with water or brine, a saturated aqueous solution of sodium chloride.

It is further preferred that prior to treating with toluene in step b), the volume of said reaction mass, or preferably of its organic phase (after removal of the aqueous phase), is reduced, preferably to about half of the volume, or more preferably to about a third of the volume. The volume reduction may be achieved by removal of the solvent by applying reduced pressure, applying a vacuum, by distillation, by evaporation or any combination thereof, preferably by applying reduced pressure. It is further preferred that ethyl-acetate is added to the reaction mass prior to reducing the volume thereof.

The temperature, at which the solvent is removed to concentrate the organic phase further, after the reaction of step a) took place and prior to the addition of toluene in step b), depends on the solvent employed. Generally the temperature may be chosen from about 20°C to about 200°C. Preferably in step b) when toluene is added to the suspension, preferably 5 to 15 times the suspension's volume, the volume is reduced further; this step may be repeated several times. Whenever more toluene is added, the volume is reduced again, thereby slowly exchanging the solvents. Preferably the mixture is stirred, preferably at 25-30°C for 30±5 minutes to reduce the volume. In step c) the temperature of the suspension is reduced to a range from -5°C to 10°C, preferably from about 0°C to 5°C. Preferably the temperature is maintained for 60 min.

In step d) the mixture is preferably filtered.

Preferably the cake is washed with toluene and dried overnight under vacuum at about 40°C.

Applying these processes improves the properties of the isolated product of formula I. It shows a higher purity profile and may survive extended storage at RT for longer than other polymorphs.

Another embodiment of the invention is the process to synthesize the intermediate compound 4- [2-[[(6R,7R)-7-amino-2-carboxy-8-oxo-5-thia-l-azabicyclo[4.2 .0]oct-2-en-3-yl]thio]-4- thiazolyl]-l-methyl-pyridinium, chloride, hydrochloride (1 : 1 : 1), according to formula V.

Reaction scheme:

Formula II Formula VI FormulaVII

Formula V

The synthetic approach to produce a compound according to formula V, requires in the first step the transformation of 5-thia-l-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 8-oxo-7-[(2- phenylacetyl)amino]-3-[[4-(4-pyridinyl)-2-thiazolyl]thio]-, diphenylmethyl ester, (6R,7R) (Formula II), preferably in its toluene hemisolvate form (formula I), as starting material into the corresponding methylated derivative 4-[2-[[(6R,7R)-2-[(diphenylmethoxy)carbonyl]-8-oxo-7- [(2-phenylacetyl)amino]-5-thia-l-azabicyclo[4.2.0]oct-2-en-3 -yl]thio]-4-thiazolyl]-l -methyl- pyridinium, 4-methylbenzenesulfonate (1 : 1) (Formula VI); by reacting with methyl-para- to luen- sulfonate.

In the second step, the obtained intermediate is reacted -without any additional isolation step- with an alcohol, preferably with phosphorous pentachloride, pyridine and iso-butanol, to give 4- [2-[[(6R,7R)-7-amino-2-[(diphenyl-methoxy)carbonyl]-8-oxo-5- thia-l-azabicyclo[4.2.0]oct-2- en-3-yl]thio]-4-thiazolyl]-l-methyl-pyridinium, chloride, hydrochloride (1 : 1 : 1) (Formula VII). In the third step, the obtained reaction mixture is treated, without any additional isolation steps, with an acid, preferably with hydrochloric acid, more preferably with a mixture of acetone and hydrochloric acid, preferably 32% hydrochloric acid, yielding 4-[2-[[(6R,7R)-7-amino-2- carboxy-8-oxo-5-thia-l-azabicyclo[4.2.0]oct-2-en-3-yl]thio]- 4-thiazolyl]-l-methyl-pyridinium, chloride, hydrochloride (1 : 1 : 1) (a compound according to formula V) as a crystalline solid, free from ammonium chloride.

The conversion of the compound of formula I to a cephalosporin derivative and/or a

pharmaceutically acceptable salt, such as ceftaroline or ceftaroline fosamil is another important aspect of the invention. Because of the use of this more stable and easier accessible intermediate compound a more cost effective synthesis of the approved drug ceftaroline is facilitated.

A further aspect of the present invention therefore is a process of synthesizing ceftaroline or ceftaroline fosamil comprising the use of the, preferably crystalline form of, toluene hemi- solvate of benzhydryl 7B-[(phenylacetyl)-amino]-3-[4-pyridyl-2-thiazolylthio]-3-ce phem-4- carboxylate.

A further embodiment of the invention is a process of synthesizing ceftaroline or ceftaroline fosamil, comprising the use of a compound according to formula V, obtained by a process which preferably comprises the methylation of a compound according to formula II, preferably the methylation of the toluene hemi-solvate thereof, a compound according to formula I, with methyl-para-toluenesulfonate, and even more preferably said process comprises a step of de- esterification with hydrochloride acid (HC1) and acetone. Preferably such a synthesis of ceftarolin is characterized by the use of a crystalline form of 4-[2-[[(6R,7R)-7-amino-2-carboxy- 8-oxo-5-thia-l-azabicyclo[4.2.0]oct-2-en-3-yl]thio]-4-thiazo lyl]-l-methyl-pyridinium, chloride, hydrochloride (1 : 1 : 1), the compound according to formula V, preferably obtained by the process described above.

Yet another aspect of the present invention, is a pharmaceutical composition comprising the toluene hemi-solvate of benzhydryl (6R,7R)-7 -[(phenylacetyl)amino]-3-[4-pyridyl-2- thiazolylthio]-3-cephem-4-carboxylate. This pharmaceutical composition preferably comprises the toluene hemi-solvate of benzhydryl (6R,7R)-7 -[(phenylacetyl)amino]-3-[4-pyridyl-2- thiazolylthio]-3-cephem-4-carboxylate in combination with a cephalosporin derivative and/or a pharmaceutically acceptable salt thereof, preferably with ceftaroline or ceftaroline fosamil. It may further comprise at least one of pharmaceutically suitable carriers, diluents, and excipients. This pharmaceutical composition can be used for treating a patient with a bacterial infection, preferably for treating a patient with community- acquired bacterial pneumonia or acute bacterial skin infections. The invention is further described by the figures and the following examples, which are solely for the purpose of illustrating specific aspects of this invention.

EXAMPLES

Instruments

XRD / XRPD

Throughout the specification the abbreviations XRD and XRPD are used interchangeably, wherein both are referring to the X-ray powder diffraction. X-ray diffraction data are obtained using X'Pert PRO PANalytical X-ray Diffractometer, CuKa radiation, having the wavelength of 1.54 A.

DSC

DSC measurement is performed using DSC 200 F3 Maia. For results exemplified in Examples 1- 3 the usual weight of sample was 2.06 mg. The temperature range was 20° -350° C, with the rate of 10°C/min.

TGA: TGA measurement is performed using Mettler Toledo TGA DSCl . The temperature range was 25° -550° C, with the rate of 10°C /min.

NMR Spectroscopy

NMR spectra of solution in deuterated dimethylsulfoxide (D ⁶ -DMSO) were obtained on a Varian MR 400 MHz spectrometer,

Mass Spectrum:

Mass spectrum has been recorded on Agilent 6530 accurate Mass Q-TOF LC/MS (or equivalent) and on Agilent 1290 infinity (or equivalent). Usual weight of sample was 0.5 mg/ml in water. Program: dry temperature was 325°C.

IR Spectrum:

IR spectrum has been recorded on a Jasco FT/IR-430 IR spectrophotometer on KBR disk. Reference Examples: Following the procedures reported in reference examples 9 and 10 of EP 1310502 Bl , it was observed that the addition of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3- [(methylsulfonyl)oxy]-3-cephem-4-carboxylate in the 4-(4-pyridyl)-l,3-thiazole-2-thiol sodium salt solution led to a severe degradation and unsuccessful isolation of the desired product. In order to avoid this problem and to replicate the crystallization of the product, the comparative experiment was repeated starting from benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate (synthesized in the laboratory), which was dissolved in the crystallization mixture of solvents at the same proportion reported in EP1310502 Bl .

Reference example 1 (according to Reference Example 9 of EP 1310502 Bl) Benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem-4- carboxylate (10 grams, 92% HPLC purity) was dissolved in THF (200 ml, 20 vol) at 25°C. The solution was clarified, diluted with EtOAc (250 ml, 25 vol) and concentrated under vacuum. The obtained sticky solid was suspended into EtOAc (25 ml, 2.5 vol) and the obtained suspension was stirred for 1.5 h, filtered, washed with MeOH (2 x 50 ml, 5 vol each) and dried under vacuum at 25°C until constant weight. Yield: 4,5 gram (45%). Observation: There was a stirring difficulty during the concentration step, where the residue became a sticky solid at low volumes and low yield of the product was observed.

Reference example 2 (according to Reference Example 10 of EP 1310502 Bl): Benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3-cephem-4- carboxylate (10 grams, 92% HPLC purity) was dissolved in THF (130 ml, 13 vol) at 25°C. The solution was clarified, cooled to 0°C, and a mixture of MeOH/H ₂ 0/AcOH (100/140/1 ml, 10/14,5/0,1 vol) was slowly added over 30 min at 0°C. The suspension was stirred for 2 h, filtered, washed with MeOH (2 x 50 ml, 5 vol each) and dried under vacuum at 25°C until constant weight. Yield: 7.5 gram (75%).

Observation: The crystallization initially showed the partial formation of a gummy precipitate, which slowly crumbled under stirring into a homogeneous suspension.

Reference example 3 (according to Reference Example 30 of EP 1310502 Bl):

Benzhydryl (6R,7R)-7B-[(phenylacetyl)amino]-3-[(methylsulfonyl)oxy]-3-c ephem-4-carboxylate (50 grams, 85,5 mmol, 97% HPLC purity) was dissolved in THF (200 ml, 4 vol) and cooled to - 3°C. A solution of 4-(4-pyridyl)-l,3-thiazole-2-thiol (20,2 grams, 104 mmol) and sodium methylate solution 30% in methanol (20 g, 104 mmol) in 40 ml of THF was added to the mixture keeping the temperature at -3°C. The mixture was stirred for 1,5 h at the same temperature and 1,04 grams (17,3 mmol) of acetic acid was added. The mixture was stirred for 1,5 h, 500 ml (10 vol) of Methanol were added (no precipitation occurred) followed by the addition of 300 ml (6 vol) of H ₂ 0. The obtained suspension was stirred for 2 h at -3°C, filtered, washed with MeOH (900 ml, 18 vol) and dried under vacuum at 30°C until constant weight. Yield: 39 gram (78%).

Observation: The crystallization begins with the addition of H ₂ 0; but showed the formation of a gummy precipitate, again, which slowly crumbled under stirring into a non-uniform suspension. The filtration was difficult due to the presence of lumps in the suspension that were crushed in order to allow the complete filtration of the solid. Example 1: Synthesis of benzhydryl (6R,7R)-7B-[(phenylacetyl)amino]-3- [(methylsulfonyl)oxy]-3-cephem-4-carboxylate

A reactor was charged, under nitrogen, with, 450 g of benzhydryl (6R,7R)-7 - [(phenylacetyl)amino]-3-hydroxy-3-cephem-4-carboxylate and 1.8 1 of acetonitrile. The temperature was regulated, to -2-0°C under stirring, then 122 g of di-isopropylethylamine were carefully charged, by maintaining the temperature at -2-0°C. The obtained mixture was left under stirring, until complete dissolution, then the temperature was lowered to -20-15°C, and 113.4 g of mesyl-chloride were carefully charged. The obtained mixture was left under stirring at -20- 15°C for 90±5 minutes then heated to 19-21°C and diluted with 5.4 1 of water. The obtained mixture was then left under stirring for 30 minutes and filtered.

The obtained cake was washed with water, ethyl acetate and the product was dried under vacuum at about 40°C yielding of 460 g of benzhydryl (6R,7R)-7 -[(phenylacetyl)amino]-3- [(methylsulfonyl)oxy]-3-cephem-4-carboxylate.

Example 2: Synthesis of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2- thiazolylthio]-3-cephem-4-carboxylate hemisolvated with toluene

A reactor was charged with 143.3 g of 4-(4-Pyridyl)-l,3-thiazole-2-thiol, 570 ml of tetrahydrofuran, 145 ml of methanol. The obtained mixture was thermo-regulated to 20-25°C, and at this temperature 126.3 g of sodium methylate solution 30% in methanol were carefully added. The obtained mixture was left under stirring until complete dissolution then cooled to -2- 0°C and maintained at that temperature.

In a different reactor a solution of 450 g of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3- [(methylsulfonyl)oxy]-3-cephem-4-carboxylate in 1.3 1 of tetrahydrofuran was prepared, which was cooled to -5-0°C. The 4-(4-pyridyl)-l ,3-thiazole-2-thiol sodium salt solution was then added to the substrate solution, by maintaining the temperature at -5-0°C. At the end of the addition the temperature was set to -2-0°C and the mixture was maintained under stirring for about 2 h. The mixture was then diluted with 2.5 1 of ethyl acetate and washed three times with brine. The aqueous phases were eliminated and the organic phase was treated with decolorizing charcoal and concentrated under reduced pressure to about half volume and diluted with 1.5 1 of toluene two times, then concentrated again under vacuum to about half volume and diluted with 700 ml of toluene. The mixture was stirred at 25-30°C for 30±5 minutes, then cooled to 0-5°C and maintained at this temperature for 60 about 1 h. The mixture was filtered, the cake washed with toluene and dried overnight under vacuum at about 40°C yielding 455 g of crystalline toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4-pyridyl-2-thiazolylthi o]-3- cephem-4-carboxylate.

MW: 1545.92 (Toluene solvated form)

Yield: 82%

DSC: 104-106 °C (melting endotherm)

TGA: weight loss of about 4.54%,

1H NMR: (D ⁶ -DMSO) δ 2.29, 3.54, 3.68, 3.93, 5.30, 5.87, 6.98, 7.16-7.38, 7.89, 8.54, 8.60 and 9.28 ppm

¹³ C NMR: (D ⁶ -DMSO) 520.99, 29.34, 40.13, 41.56, 58.41, 59.59, 79.24, 1 18.47, 120.20, 121.55, 125.26, 126.47-140.12, 150.36, 125.86, 160.41, 161.23, 164.77, 170.92 ppm;

IR spectrum (KBr): 3280 (NH), 3034 (CH-aromatic), 2960,(CH-aliphatic), 1791 (β-Lactum C=0), 1702 (Ester C=0), 1654 (Amide C=0), 1535 (Pyridine C=N) and 1011 (C-O), cm-1

Mass spectrum: m/z = [M+] = 677.13 (Non-solvated form) Example 3 The stability of the toluene hemi-solvate of benzhydryl (6R,7R)-7P-[(phenylacetyl)amino]-3-[4- pyridyl-2-thiazolylthio]-3-cephem-4-carboxylate at room temperature was tested in order to evaluate the possibility to store the product under standard condition (20-30°C). Unfortunately attempts to reproduce the disclosed processes of EP1310502 (reference examples) resulted in products of such a low yield and/or poor stability of the crystalline form that no reasonable amount of product could be obtained in order to set up a comparative stability testing.

The sample was left at room temperature (20-30°C) and was analysed again after 11 months. The following results were obtained:

These data confirm the high stability of the new crystalline form and its possibility to store under standard condition.

Reference Example 4 (according to Reference example 14 of EP 1310502 Bl):

4-[2-[[(6R,7R)-7-amino-2-[(diphenylmethoxy)carbonyl]-8-ox o-5-thia-l-azabicyclo[4.2.0]oct-2- en-3-yl]thio]-4-thiazolyl]-l-methyl-pyridinium chloride, hydrochloride (1 : 1 : 1) (7 grams, 10,32 mmol, HPLC purity 90%) was suspended in acetonitrile (56 ml, 8 vol) at RT; HC1 32% (56 ml, 8 vol) was slowly added into the mixture over 20 min. The mixture was stirred for 10 min (clear solution observed) and EtOAc (112 ml, 16 vol) was added. The mixtrure was stirred for 5 hrs at RT, during which a precipitate was formed. The suspension was filtered, washed with acetonitrile (2 x 16 ml, 2 x 2,3 vol) and dried under vacuum at 25°C until constant weight to give the compound according to formula V. Yield: 3,6 gram (73%) Reference Example 5 (according to Reference example 15 of EP 1310502 Bl):

Phosphorus pentachloride (6,66 g, 32 mmol) was suspended in dichloromethane (55 mL, 6 vol), cooled to 0/-2°C and pyridine (2,53 g, 32 mmol) was added dropwise over 15 min. The mixture was stirred for 30 min. Then, a powder (9,7 g, 10,68 mmol, HPLC purity 95%) of 4-[2- [[(6R,7R)-2-[(diphenylmethoxy)carbonyl]-8-oxo-7-[(2-phenylac etyl)amino]-5-thia-l- azabicyclo[4.2.0]oct-2-en-3-yl]thio]-4-thiazolyl]- 1 -methylpyridinium, 4-methylbenzenesulfonate (1 : 1) was added over 15 min, and the mixture was stirred for 1 ,5 hr. The reaction mixture was cooled to -5/-7°C and isobutyl alcohol (55 mL, 6 vol) was added. The mixture was stirred at 25°C for 3 hrs, and concentrated to about 100 mL. Acetonitrile (55 mL, 6 vol) and 32% HC1 (55 mL, 6 vol) were added and the mixture was stirred at 40°C for 2 hrs. The obtained suspension was filtered, washed with acetonitrile (2 x 22 ml, 2 x 2,4 vol) and dried under vacuum at 25 °C until constant weight. Yield: 3,0 g (59%)

NOTE:, 4-[2-[[(6R,7R)-2-[(diphenylmethoxy)carbonyl]-8-oxo-7-[(2-phe nylacetyl)amino]-5-thia-

1- azabicyclo[4.2.0]oct-2-en-3-yl]thio]-4-thiazolyl]-l-methyl-p yridinium, 4-methyl-benzene- sulfonate (1 : 1) was used instead of 4-[2-[[(6R,7R)-2-[(diphenylmethoxy)carbonyl]-8-oxo-7-[(2- phenylacetyl)amino]-5-thia-l-azabicyclo[4.2.0]oct-2-en-3-yl] thio]-4-thiazolyl]-l -methyl pyridinium, iodide (1: 1) for this experiment.

Example 4: Synthesis of 4-[2-[[(6R,7R)-7-amino-2-carboxy-8-oxo-5-thia-l- azabicyclo[4.2.01oct-2-en-3-yllthiol-4-thiazolyll-l -methyl pyridinium. chloride, hydrochloride (1 : 1 : 1) according to the process as claimed

A glass round bottom flask was charged with 35g (51 ,7 mmol) of 5-Thia-l-azabicyclo[4.2.0]oct-

2- ene-2-carboxylic acid, 8-oxo-7-[(2-phenylacetyl)amino]-3-[[4-(4-pyridinyl)-2-thiazo lyl]thio]-, diphenylmethyl ester, (6R,7R) and 75 mL of dichloromethane, at 25°C. To the obtained solution were added 48 mL (258,5 mmol) of methyl paratoluenesulphonate and the mixture was heated to reflux and maintained for 12 hours under reflux, then cooled to room temperature.

In glass lined reactor were charged 32,3 g (155,1 mmol) of phosphorous pentachloride and 75 mL of dichloromethane. The obtained suspension was cooled to -5÷0°C and 12.3 g (155,1 mmol) of pyridine were added dropwise by maintaining the temperature at -5÷0°C, then the mixture was maintained under stirring for 15 minutes at the same temperature.

To the mixture, cooled to -10÷-5°C, was carefully added the solution prepared in the round bottom flask, keeping the temperature between -10÷-5°C; the mixture thus obtained was maintained under stirring for 2 hours at the same temperature. 105 mL of isobutanol were carefully added, in about 30 minutes, by maintaining the temperature at -5°C÷0°C; the obtained mixture was heated at 28÷30°C and left to react at the same temperature for 3.5 hours. The mixture was concentrated under vacuum to 1/3 of its volume, diluted with 200 mL of acetone and maintained under stirring for 1 hour at 25÷30°C. 70 mL of 32% hydrochloric acid were added, keeping the temperature in the range of 25÷30°C, and the mixture was maintained under stirring overnight. The obtained suspension was filtered, the cake was washed with acetone (2 x 35 ml). The wet solid was dried under vacuum at 40°C overnight yielding 18.4 g (38,4 mmol) of 4-[2-[[(6R,7R)-7-amino-2-carboxy-8-oxo-5-thia-l- azabicyclo[4.2.0]oct-2-en-3-yl]thio]-4-thiazolyl]-l -methyl pyridinium, chloride, hydrochloride (1 : 1 : 1) as a crystalline solid. Yield 74,3% Observation: The 4-[2-[[(6R,7R)-7-amino-2-carboxy-8-oxo-5-thia-l-azabicyclo[4 .2.0]oct-2-en- 3-yl]thio]-4-thiazolyl]-l-methyl-pyridinium chloride, hydrochloride (1 : 1 : 1) crystal forms isolated with the procedures described in the art (Reference Examples 14 and 15) were analysed with the XRPD technique and the obtained difiractograms compared with the one obtained from the experimental procedure of Example 4, according to the invention. All three analysed samples were found to be characterized by the same crystallographic pattern (see Figure 7), wherein the peaks of the sample according to Example 4 (bottom position) were slightly more intense.