WO2010094738A1

WO2010094738A1 - Phosphate ester of a 4-pyridone derivative and its use in the chemotherapy of parasitic infections

Info

Publication number: WO2010094738A1
Application number: PCT/EP2010/052045
Authority: WO
Inventors: Jose Maria Bueno-Calderon; Jose Maria Fiandor-Roman; Margarita Puente-Felipe; Jesus Chicharro-Gonzalo; Senthil Kumar Kusalakumari Sukumar; Mehran Maleki
Original assignee: Glaxo Group Limited
Priority date: 2009-02-20
Filing date: 2010-02-18
Publication date: 2010-08-26
Also published as: UY32458A; AR075522A1; TW201039834A

Abstract

A 4-pyridone (4-pyridinone) derivative of Formula I and pharmaceutically acceptable salts thereof, crystalline forms of said 4-pyridone derivative and salts thereof, pharmaceutical compositions comprising such 4-pyridone derivative and salts thereof and the use of the pharmaceutical compostitions in the chemotherapy of certain parasitic infections such as malaria, and in particular infection by Plasmodium falciparum.

Description

PHOSPHATE ESTER OF A 4-PYRIDONE DERIVATIVE AND ITS USE IN THE CHEMOTHERAPY OF

PARASITIC INFECTIONS

TECHNICAL FIELD

The invention relates to heterocyclic compounds and their use in chemotherapy. More specifically, this invention is concerned with certain 4-pyridone (4-pyridinone) derivatives and crystalline forms thereof, processes for their preparation, pharmaceutical formulations thereof and their use in chemotherapy of certain parasitic infections such as malaria, and in particular infection by Plasmodium falciparum.

BACKGROUND OF THE INVENTION

Parasitic protozoal infections are responsible for a wide variety of diseases of medical and veterinary importance, including malaria in man and various coccidioses in birds, fish and mammals. Many of the diseases are life-threatening to the host and cause considerable economic loss in animal husbandry, such as diseases caused by infection with species of Eimeria, Theileria, Babesia, Cryptosporidium, Toxoplasma (such as Toxoplasma brucei, African sleeping sickness and Toxoplasma cruzi, Chagas disease) and Plasmodium (such as Plasmodium falciparum), and the Mastigophora such as species of Leishmania (such as Leishmania donovani). Another parasitic organism of increasing concern is Pneumocytis carinii, which can cause an often fatal pneumonia in immunodeficient or immunocompromised hosts, including those infected with HIV.

Malaria is one of the major disease problems of the developing world. The most virulent malaria-causing parasite in humans is the parasite Plasmodium falciparum, which is the cause of hundreds of millions of cases of malaria per annum, and is thought to cause over 1 million deaths each year, Breman, J. G., et al., (2001 ) Am. Trop. Med. Hyg. 64, 1-1 1. One problem encountered in the treatment of malaria is the build-up of resistance by the parasite to available drugs. Thus, there is a need to develop new antimalarial drugs.

Cases of uncomplicated malaria are conveniently treated by the enteral administration of an oral dosage form. However in severe cases of malaria it would be advantageous to administer a medicament parenterally, for example, by injection or infusion.

PCT Patent Application No. WO 91/13873 A1 discloses 4-pyridone derivatives which exhibit activity against protozoa, in particular against the malarial parasite Plasmodium falciparum, and species of Eimeria as well as the parasitic organism Pneumocytis carinii. PCT Patent Application No. WO 2007/138048 discloses a class of compounds that are generically disclosed in WO 91/13873 A1 but which have a specific substitution pattern and have been found to exhibit improved properties over compounds exemplified in WO 91/13873 A1. In particular, the class of 4-pyridone derivatives disclosed in WO 2007/138048 have been found to show promise as a treatment for uncomplicated malaria. The class of 4-pyridone derivatives disclosed in WO 2007/138048 has been found by the present inventors to have a relatively low solubility in aqueous media. Accordingly, there remains a need for more soluble derivatives that show a better pharmacokinetic profile in terms of oral bioavailability and exposure. In addition, compounds with higher solubility in aqueous media may have the potential for parenteral administration, for example, in the treatment of complicated malaria. It is an object of the invention to identify 4-pyridone derivatives that have an enhanced solubility in aqueous media.

An array of different avenues could be explored by the skilled person when seeking to increase the water solubility of a chemical compound. The skilled person could, for example, have prepared various salts of the 4-pyridone derivatives disclosed in WO 2007/138048. Furthermore, the skilled person could design specific formulations to increase the solubility of the active pharmaceutical ingredient. Alternatively, the skilled person could consider modifying the chemical structure of the compound to increase its polarity and hence its water solubility.

Pyridone compounds can exist in different tautomeric forms, where either the oxygen atom (in the case of the 4-pyridinol form) or the ring nitrogen atom (in the case of the 4- pyridone form) is protonated.

4-pyridone 4-pyridinol

The alcohol functional group of the 4-pyridinol form can be modified to generate a prodrug, such as a carbamate or an ester that is metabolised in vivo to release the desired compound. Therefore, one possible approach to increase the solubility of the 4- pyridone derivatives disclosed in WO 2007/138048 might be to form a prodrug of the 4- pyridinol tautomeric form.

The present inventors explored with little success a number of different possible approaches in order to increase the solubility of 4-pyridone derivatives whilst retaining the desirable properties of those compounds.

Compounds disclosed in WO 2007/138048 of the formula:

wherein R¹ represents halo, CF₃ or OCF₃ and R⁴ represents halo, were identified by the present inventors as having a specific substitution pattern including a primary alcohol functional group that provides a second functional group that could be modified to generate a prodrug in addition to or as an alternative to the alcohol of the 4-pyridinol tautomeric form.

It was found that {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate, which is the phosphate ester of 3-chloro-6-(hydroxymethyl)-2-methyl-5-[4-({4-

[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-4(1 H)-pyridinone, a compound that has a specific substitution pattern and that has been modified to a particular prodrug form, exhibits improved properties, and in particular increased water solubility, over those compounds specifically disclosed in WO 2007/138048.

It is a further object of the invention to identify stable crystalline forms of {5-chloro-6- methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2- pyridinyl}methyl dihydrogen phosphate that are suitable for use in pharmaceutical compositions.

SUMMARY OF THE INVENTION

This invention is directed to {5-chloro-6-methyl-4-oxo-3-[4-({4-

[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate and salts thereof, crystalline solids forms of such a compound or salt, methods of making such a compound or salt, pharmaceutical compositions comprising such a compound or salt and use of the compound or salt in the chemotherapy of certain parasitic infections such as malaria, and in particular infection by Plasmodium falciparum.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 a shows the X-ray powder diffraction (XRPD) pattern of Form 1A. Figure 1 b shows the FT-Raman spectrum of Form 1A. Figure 1 c shows the DSC data for Form 1A. Figure 1 d shows the TGA data for Form 1A. Figure 1 e shows the solid-state ¹³C NMR spectrum for Form 1A. Figure 1f shows the solid-state ¹⁹F NMR spectrum for Form 1 A. Figure 1g shows the solid-state ³¹P NMR spectrum for Form 1A.

Figure 2a shows the XRPD pattern of Form 1 C.

Figure 2b shows the FT-Raman spectrum of Form 1 C.

Figure 2c shows the DSC data for Form 1 C. Figure 2d shows the TGA data for Form 1 C.

Figure 2e shows the solid-state ¹³C NMR spectrum for Form 2A.

Figure 2f shows the solid-state ¹⁹F NMR spectrum for Form 2A.

Figure 2g shows the solid-state ³¹P NMR spectrum for Form 2A.

Figure 3a shows the XRPD pattern for Form 1 F. Figure 3b shows the FT-Raman spectrum for Form 1 F.

Figure 3c shows the DSC data for Form 1 F.

Figure 3d shows the TGA data for Form 1 F.

Figure 3e shows the TG-IR data for Form 1 F.

Figure 3f shows the solid-state ¹³C NMR spectrum for Form 1 F. Figure 3g shows the solid-state ¹⁹F NMR spectrum for Form 1 F.

Figure 3h shows the solid-state ³¹P NMR spectrum for Form 1 F.

Figure 4a shows the XRPD pattern for Form 1 G.

Figure 4b shows the DSC data for Form 1 G.

Figure 4c shows the TGA data for Form 1 G. Figure 4d shows the TG-IR data for Form 1 G.

Figure 5a shows the XRPD pattern for Form 2G.

Figure 5b shows the FT-Raman spectrum for Form 2G.

Figure 5c shows the DSC data for Form 2G.

Figure 5d shows the TGA data for Form 2G. Figure 6 shows an overlay of the solubility profile of a compound of the invention and a comparative compound.

DESCRIPTION OF THE EMBODIMENTS

The present invention provides a compound of Formula I:

I as the free acid, or a salt of the compound of Formula I. The free acid or salt forms may either be solvated or non-solvated. The compound of Formula I is advantageously hydrolysable under in vivo conditions in the human body to leave the parent acid or a salt thereof. In one aspect, the invention provides a crystalline solid of a compound of Formula I as the free acid, or a crystalline solid of a salt of the compound of Formula I. The free acid or salt crystalline solid forms may either be solvated or non-solvated.

In one aspect, the invention is directed to certain crystalline forms of {5-chloro-6-methyl-4- oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate and salts thereof. In a further aspect, the invention is directed to such crystalline forms for use in medical therapy or for use in the manufacture of a medicament for the treatment of malaria. In another aspect, the invention is directed to a method for the treatment of a human or animal subject suffering from malaria, for example malaria that is caused by infection with Plasmodium falciparum, comprising administering to said human or animal subject an effective amount of a crystalline solid of the invention. In another aspect, the invention is directed to a pharmaceutical composition comprising crystalline solid of the invention and one or more pharmaceutically acceptable carriers and/or excipients. In one aspect, the pharmaceutical composition of the invention is suitable for parenteral administration and/or is in the form of a solid for reconstitution into a liquid dosage form. In one aspect, the pharmaceutical composition of the invention comprises solid particles that comprise the compound of Formula I or a salt thereof, said solid particles having an average maximum dimension of from 0.01 to 100 micron. In one aspect, the the pharmaceutical composition of the invention comprises a combination of a crystalline solid of he invention and a further active thereapeutic agent.

It has been found that the non-solvated free acid of {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate can be obtained in a crystalline form (Form 1A). It has also been found that the non-solvated tromethamine salt of {5-chloro-6-methyl-4-oxo-3-[4-({4-

[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate can be obtained in a crystalline form (Form 1 C). It has also been found that the hydrated mono-sodium salt of {5-chloro-6-methyl-4-oxo-3-[4-({4-

[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate can be obtained in a crystalline form (Form 1 F). It has also been found that the hydrated mono-potassium salt of {5-chloro-6-methyl-4-oxo-3-[4-({4-

[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate can be obtained in a crystalline form (Form 1 G). It has also been found that the non-solvated mono-potassium salt of {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate can be obtained in a crystalline form (Form 2G).

Free acids of the compound of Formula I In one aspect, the invention provides a compound of Formula I as a free acid. In a further aspect, the invention provides a compound of Formula I as a free acid in the form of an amorphous solid. In a yet further aspect, the invention provides a compound of Formula I as a free acid in the form of a crystalline solid.

In one aspect of the invention, the crystalline forms of the compound of Formula I as a free acid are non-solvated. Crystalline forms may be characterized and differentiated using a number of conventional analytical techniques, including but not limited to X-ray powder diffraction (XRPD), Raman spectroscopy, solid-state ¹³C NMR spectroscopy, solid-state ¹⁹F NMR spectroscopy, solid-state ³¹P NMR spectroscopy and differential scanning calorimetry (DSC).

In one aspect, the invention provides a compound of Formula I as a free acid in the form of a non-solvated crystalline solid (Form 1A).

In one embodiment, Form 1A may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) spectra comprising 2 theta angle peaks, for example peaks at 5% or greater relative intensity, at the positions set out in Table 1 to ±0.2°:

Table 1

In one embodiment, Form 1A may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 1 a. In a further embodiment, Form 1A may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 1 a, and/or with characteristic 2 theta angle peaks at the positions set out in Table 1 a or Table 1 b to ±0.2°, wherein the data was obtained using a diffracted beam monochromator equipped with a suitable detector, such as the PANalytical X'Pert Pro diffractometer equipped with an X'Celerator detector, using Cu K-alpha (1.5406 A) radiation. In another embodiment, the sample is flattened on a zero-background silicon holder and is run immediately after preparation under ambient conditions, a continuous 2-theta scan range of 2° to 50° is used with a Cu K-alpha (1.5406 A) radiation source and a generator power of 45 kV and 40 mA, and a step size of 0.0167 degrees per 2-theta step is used and the sample is rotated at 30 rpm.

In one embodiment, Form 1A may be characterised as a crystalline solid, which provides bands on the FT-Raman spectrum at: 593, 818, 854, 1 166, 1215, 1612, 2946, 3076 cm^"1 to ±6 cm^"1, preferably to ±4 cm^"1. In a further embodiment, Form 1A may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum substantially in accordance with Figure 1 b. In another embodiment, Form 1A may be characterised as a crystalline which provides bands on the FT-Raman spectrum at: 593, 818, 854, 1 166, 1215, 1612, 2946, 3076 cm^"1 to ±6 cm^"1, preferably to ±4 cm^"1 and/or which provides bands on the FT-Raman spectrum substantially in accordance with Figure 1 b wherein Raman spectra are recorded on a Nicolet NXR 9650 FT-Raman Spectrometer, at 4 cm^"1 resolution with excitation from a Nd: YVO4 laser (λ = 1064 nm).

In one embodiment, Form 1A may be characterised as a crystalline solid which provides ¹³C solid-state NMR spectra having at least 14 peaks, preferably at least 18 peaks, more preferably at least 22 peaks and especially at least 24 peaks selected from peaks at (δ, ppm from tetramethylsilane): 170.6, 167.9, 156.5, 155.1 , 153.3, 152.8, 149.9, 148.1 , 146.1 , 145.6, 143.5, 142.5, 135.9, 133.2, 132.5, 131.2, 127.0, 124.5, 122.3, 119.3, 117.6, 116.9, 115.1 , 114.0, 62.6, 61.5, 19.5 and 17.3 to ±0.4 ppm, preferably to ±0.2 ppm. In a further embodiment, Form 1A may be characterised as a crystalline solid which provides ¹³C solid-state NMR spectra having at least 16 peaks, preferably at least 18 peaks, more preferably at least 20 peaks and especially at least 21 peaks selected from peaks at (δ, ppm from tetramethylsilane): 156.5, 155.1 , 153.3, 152.8, 149.9, 148.1 , 146.1 , 145.6, 143.5, 142.5, 135.9, 133.2, 132.5, 131.2, 127.0, 124.5, 122.3, 1 19.3, 1 17.6, 1 16.9, 1 15.1 and 114.0 to ±0.4 ppm, preferably to ±0.2 ppm. In a yet further embodiment, Form 1 A may be characterised as a crystalline solid which provides ³C solid-state NMR spectra having at least 12 peaks, preferably at least 14 peaks, more preferably at least 16 peaks and especially at least 18 peaks selected from peaks at (δ, ppm from tetramethylsilane): 156.5, 155.1 , 153.3, 152.8, 146.1 , 145.6, 143.5, 142.5, 133.2, 132.5, 131.2, 127.0, 124.5, 122.3, 119.3, 1 17.6, 1 16.9, 1 15.1 and 114.0 to ±0.4 ppm, preferably to ±0.2 ppm.

In one embodiment, Form 1A may be characterised as a crystalline solid which provides ¹⁹F solid-state NMR spectra having a peak at (δ, ppm from CF₃CI₃): -54.5 to ±0.2 ppm.

In one embodiment, Form 1A may be characterised as a crystalline solid which provides ³¹P solid-state NMR spectra having peaks at (δ, ppm from 85% H₃PO₄): -0.3, and -1.4 ±0.2 ppm. In another embodiment, Form 1A may be characterised as a crystalline solid which provides a ³¹P solid-state NMR spectrum substantially in accordance with Fig. 1g.

Preferably, a crystalline solid of Form 1A may be characterised by more than one of the above analytical techniques. Advantageously, Form 1A combines the features of at least one embodiment described above for each of any two different, for example any three different, preferably any four different, and especially all five, analytical techniques described above. In one aspect of the invention, the crystalline solid of Form 1A may, additionally, have the characteristics of any one or more of the embodiments described below.

In one embodiment, Form 1A may be characterised as a crystalline solid which has an onset of melting in the range 162-165 ⁰C, more particularly an onset of melting in the range 163-164 ⁰C and especially an onset of melting of approximately 163.3 ⁰C. In a further embodiment, Form 1A may be characterised as a crystalline solid which has an enthalpy of melting in the range of 56-63 J/g, more particularly an enthalpy of melting in the range of 58-61 J/g and especially and an enthalpy of melting of approximately 59.3 J/g as measured by DSC. In another embodiment, Form 1A may be characterised as a crystalline solid which provides a DSC thermogram substantially in accordance with Figure 1 c.

In one embodiment, Form 1A may be characterised as a crystalline solid, which provides a TGA thermogram substantially in accordance with Figure 1d.

Salts of the compound of Formula I

It will be appreciated that certain pharmaceutically acceptable salts of the compound according to Formula I may be prepared, since the compounds of the invention are weakly amphoteric. Indeed, in certain embodiments of the invention, pharmaceutically acceptable salts of the compounds according to Formula I may be preferred over the respective free base or free acid because such salts impart greater stability or solubility to the molecule thereby facilitating formulation into a dosage form. The compounds of the present invention may also be administered as a pharmaceutically acceptable salt. Accordingly, the invention is further directed to pharmaceutically acceptable salts of the compounds according to Formula I. The invention includes within its scope all possible stoichiometric and non-stoichiometric forms of the salts of the compound of Formula I.

In one aspect, the invention provides a salt of the compound of Formula I, for example a pharmaceutically acceptable salt. As used herein, the term "pharmaceutically acceptable salts" refers to salts that substantially retain the desired biological activity of the subject compound and exhibit minimal undesired toxicological effects. For a review on suitable salts see Berge et al, J. Pharm. ScL, 1977, 66, 1-19. The term "pharmaceutically acceptable salts" includes both pharmaceutically acceptable acid addition salts and pharmaceutically acceptable base addition salts. These pharmaceutically acceptable salts may be prepared in situ during the final isolation and purification of the compound, or by separately reacting the purified compound in its free acid or free base form with a suitable base or acid, respectively. The salt may precipitate from solution and be collected by filtration or may be recovered by evaporation of the solvent.

Compounds according to Formula I contain an acidic functional group and may therefore be capable of forming base addition salts by treatment with a suitable base. A pharmaceutically acceptable base addition salt may be formed by reaction of a compound of Formula I with a suitable inorganic base or a organic base, optionally in a suitable solvent such as an organic solvent, to give the base addition salt which may be isolated for example by crystallisation, filtration and freeze drying processes. Pharmaceutically acceptable base salts include pharmaceutically acceptable metal salts, for example pharmaceutically acceptable alkali-metal or alkaline-earth-metal salts such as hydroxides, sodium, potassium, lithium, and pharmaceutically acceptable amine salts such as tromethamine (alternatively known as 2-amino-2-(hydroxymethyl)-1 ,3-propanediol) salts.

In one aspect, the invention provides a salt of the compound of Formula I, for example a pharmaceutically acceptable salt. In one aspect, the invention is further directed to pharmaceutically acceptable base additions salts of the compounds according to Formula I, for example, a tromethamine, sodium, potassium or lithium salt of the compound of Formula I.

In one aspect, the invention provides a salt of the compound of Formula I, for example a pharmaceutically acceptable salt, as a crystalline solid. In one aspect, the invention provides crystalline solid forms of pharmaceutically acceptable salts of the compounds according to Formula I. Crystalline solid forms of such salts may be preferred over the respective amorphous material.

A screen was conducted for salt forms of the compound of Formula I that were crystalline and had acceptable thermal stability profiles. From amongst the salts prepared, tromethamine, sodium and potassium salt forms were identified that were crystalline and which displayed acceptable thermal properties.

Tromethamine salts

In one aspect of the invention, there is provided a tromethamine salt of the compound of

Formula I. In a further aspect of the invention, there is provided a tromethamine salt of the compound of Formula I in the form of a crystalline solid. In another aspect, the invention provides a non-solvated tromethamine salt of the compound of Formula I in the form of a crystalline solid. Crystalline forms of the tromethamine salt of the compound of Formula I may be characterized and differentiated using a number of conventional analytical techniques, including but not limited to X-ray powder diffraction (XRPD), Raman spectroscopy, solid-state ¹³C NMR spectroscopy, solid-state ¹⁹F NMR spectroscopy, solid- state ³¹P NMR spectroscopy and differential scanning calorimetry (DSC).

In one aspect of the invention, there is provided a tromethamine salt of the compound of Formula I as a non-solvated crystalline solid (Form 1C).

In one embodiment, Form 1 C may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) spectrum comprising 2 theta angle peaks at the positions, for example at 5% or greater relative intensity, set out in Table 2 to ±0.2°:

Table 2

In one embodiment, Form 1 C may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 2a. In a further embodiment, Form 1 C may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 2a, and/or with characteristic 2 theta angle peaks at essentiality the positions set out in Table 2a or Table 2b to ±0.2°, wherein the data was obtained using a diffracted beam monochromator equipped with a suitable detector (such as the PANalytical X'Pert Pro diffractometer equipped with an X'Celerator detector) using Cu K-alpha (1.5406 A) radiation. In another embodiment, the sample is flattened on a zero-background silicon holder and is run immediately after preparation under ambient conditions, a continuous 2- theta scan range of 2° to 50° is used with a Cu K-alpha (1.5406 A) radiation source and a generator power of 45 kV and 40 mA, and a step size of 0.0167 degrees per 2-theta step is used and the sample is rotated at 30 rpm. In one embodiment, Form 1 C may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum at: 604, 810, 850, 1090, 1202, 1297, 1549, 1619, 2901 , 2959, 3077 cm^"1 to ±6 cm^"1, preferably to ±4 cm^"1. In a further embodiment, Form 1 C may be characterised as a crystalline solid, which provides bands on the FT-Raman spectrum substantially in accordance with Figure 2b. In another embodiment, Form 1 C may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum at: 604, 810, 850, 1090, 1202, 1297, 1549, 1619, 2901 , 2959, 3077 cm^"1 to ±6 cm^"1, preferably to ±4 cm^"1 and/or which provides bands on the FT-Raman spectrum substantially in accordance with Figure 2b wherein Raman spectra are recorded on a Nicolet NXR 9650 FT-Raman Spectrometer, at 4 cm^"1 resolution with excitation from a Nd: YVO4 laser (λ = 1064 nm).

In one embodiment, Form 1 C may be characterised as a crystalline solid which provides ¹³C solid-state NMR spectra having at least 14 peaks, preferably at least 16 peaks, more preferably at least 18 peaks and especially at least 20 peaks selected from peaks at (δ, ppm from tetrmethylsilane): 173.0, 158.7, 154.9, 147.4, 145.8, 141.2, 133.2, 131.2, 127.9, 127.4, 126.4, 124.2, 122.3, 120.7, 120.1 , 117.4, 1 14.1 , 63.8, 58.9, 57.5 and 16.9 to ±0.4 ppm, preferably to ±0.2 ppm. In a further embodiment, Form 1 C may be characterised as a crystalline solid which provides ¹³C solid-state NMR spectra having at least 10 peaks, preferably at least 12 peaks, more preferably at least 14 peaks and especially at least 15 peaks selected from peaks at (δ, ppm from tetrmethylsilane): 158.7, 154.9, 147.4, 145.8, 141.2, 133.2, 131.2, 127.9, 127.4, 126.4, 124.2, 122.3, 120.7, 120.1 , 1 17.4 and 1 14.1 to ±0.4 ppm, preferably to ±0.2 ppm. In a further embodiment, Form 1 C may be characterised as a crystalline solid which provides ¹³C solid-state NMR spectra having at least 6 peaks, preferably at least 7 peaks, more preferably at least 8 peaks and especially 9 peaks selected from peaks at (δ, ppm from tetrmethylsilane): 158.7, 154.9, 147.4, 145.8, 141.2, 133.2, 127.9, 126.4 and 124.2 to ±0.2 ppm.

In another embodiment, Form 1 C may be characterised as a crystalline solid which pprroo vviiedes ¹⁹F solid-state NMR spectra having a peak at (δ, ppm from CF₃CI₃): -58.3 to ±0.2 ppm.

In a further embodiment, Form 1 C may be characterised as a crystalline solid which provides ³¹P solid-state NMR spectra having a peak at (δ, ppm from 85% H₃PO₄): -1.1 to ±0.2 ppm.

Preferably, a crystalline solid of Form 1 C may be characterised by more than one of the above analytical techniques. Advantageously, Form 1 C combines the features of at least one embodiment described above for each of any two different, for example any three different, preferably any four different, and especially all five, analytical techniques described above. In one aspect of the invention, the crystalline solid of Form 1 C may, additionally, have the characteristics of any one or more of the embodiments described below.

In one embodiment, Form 1 C may be characterised as a crystalline solid which has an onset of melting in the range 165-169 ⁰C, more particularly an onset of melting in the range 166-168 ⁰C and especially an onset of meting of approximately 166.9 ⁰C. In a further embodiment, Form 1 C may be characterised as a crystalline solid which has an enthalpy of melting in the range of 68-75 J/g, more particularly an enthalpy of melting in the range of 70-73 J/g and especially and an enthalpy of melting of approximately 71.3 J/g as measured by DSC. In another embodiment Form 1 C may be characterised as a crystalline solid which provides a DSC thermogram substantially in accordance with Figure 2c.

In a one embodiment, Form 1 C may be characterised as a crystalline solid which provides a TGA thermogram substantially in accordance with Figure 2d.

Sodium salts

In one aspect, the invention provides a sodium salt of the compound of Formula I. In a further aspect, the invention provides a sodium salt of the compound of Formula I in the form of a crystalline solid. In another aspect, the invention provides a hydrated sodium salt of the compound of Formula I in the form of a crystalline solid. Crystalline forms of the sodium salt of the compound of Formula I may be characterized and differentiated using a number of conventional analytical techniques, including but not limited to X-ray powder diffraction (XRPD), Raman spectroscopy, solid-state ¹³C NMR spectroscopy, solid-state ¹⁹FF NNMMRR ssppeeccttrrooεscopy, solid-state ³¹P NMR spectroscopy and differential scanning calorimetry (DSC).

In one aspect, the invention provides a hydrated sodium salt of the compound of Formula I in the form of a crystalline solid (Form 1F).

In one embodiment, Form 1 F may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) spectrum comprising 2 theta angle peaks at essentially the positions, for example at 5% or greater relative intensity set out in Table 3 to ±0.2°:

Table 3

In one embodiment, Form 1 F may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 3a. In another embodiment, Form 1 F may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 3a, wherein the data was obtained using a diffracted beam monochromator equipped with a suitable detector (such as the PANalytical X'Pert Pro diffractometer equipped with an X'Celerator detector) using Cu K-alpha (1.5406 A) radiation. In a further embodiment, the sample is flattened on a zero-background silicon holder and is run immediately after preparation under ambient conditions, a continuous 2-theta scan range of 2° to 50° is used with a Cu K-alpha (1.5406 A) radiation source and a generator power of 45 kV and 40 mA, and a step size of 0.0167 degrees per 2-theta step is used and the sample is rotated at 30 rpm.

In one embodiment, Form 1 F may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum at essentially: 598, 816, 847, 1207, 1298, 1616, 2946, 3061 cm^"1 to ±6 cm^"1, preferably to ±4 cm^"1. In a further embodiment, Form 1 F may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum substantially in accordance with Figure 3b. In a further embodiment, Form 1 F may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum at essentially: 604, 810, 850, 1090, 1202, 1297, 1549, 1619, 2901 , 2959, 3077 cm^"1 to ±6 cm^"1, preferably to ±4 cm^"1 and/or which provides bands on the FT-Raman spectrum substantially in accordance with Figure 3b wherein Raman spectra are recorded on a Nicolet NXR 9650 FT-Raman Spectrometer, at 4 cm^"1 resolution with excitation from a Nd: YVO4 laser (λ = 1064 nm).

In one embodiment, Form 1 F may be characterised as a crystalline solid which provides ¹³C solid-state NMR spectra having at least 14 peaks, preferably at least 16 peaks, more preferably at least 18 peaks and especially 20 peaks selected from peaks at (δ, ppm from tetrmethylsilane): 173.6, 157.1 , 155.4, 147.2, 147.0, 144.1 , 142.8, 132.6, 132.0, 128.6, 127.8, 125.4, 124.3, 123.2, 122.3, 120.9, 120.0, 118.0, 114.0, 62.3 and 18.5 to ±0.4 ppm, preferably to ±0.2 ppm. In a further embodiment, Form 1 F may be characterised as a crystalline solid which provides ¹³C solid-state NMR spectra having at least 12 peaks, preferably at least 14 peaks, more preferably at least 16 peaks and especially at least 17 peaks selected from peaks at (δ, ppm from tetrmethylsilane): 157.1 , 155.4, 147.2, 147.0, 144.1 , 142.8, 132.6, 132.0, 128.6, 127.8, 125.4, 124.3, 123.2, 122.3, 120.9, 120.0, 1 18.0 and 114.0 to ±0.4 ppm, preferably to ±0.2 ppm. In a yet further embodiment, Form 1 F may be characterised as a crystalline solid which provides ¹³C solid-state NMR spectra having at least 10 peaks, preferably at least 12 peaks, more preferably at least 14 peaks and especially 15 peaks selected from peaks at (δ, ppm from tetrmethylsilane): 157.1 , 155.4,

147.2, 147.0, 144.1 , 142.8, 132.6, 132.0, 128.6, 127.8, 125.4, 124.3, 123.2, 122.3, 1 18.0 and 114.0 to ±0.4 ppm, preferably to ±0.2 ppm.

In one embodiment, Form 1 F may be characterised as a crystalline solid which provides ¹⁹F solid-state NMR spectra having a peak at (δ, ppm from CF₃CI₃): -56.9 to ±0.2 ppm.

In a further embodiment, Form 1 F may be characterised as a crystalline solid which provides ³¹P solid-state NMR spectra having a peak at (δ, ppm from 85% H₃PO₄): 4.8 to±0.2 ppm.

Preferably, a crystalline solid of Form 1 F may be characterised by more than one of the above analytical techniques. Advantageously, Form 1 F combines the features of at least one embodiment described above for each of any two different, for example any three different, preferably any four different, and especially all five, analytical techniques described above. In one aspect of the invention, the crystalline solid of Form 1 F may, additionally, have the characteristics of any one or more of the embodiments described below.

In one embodiment, Form 1 F may be characterised as a crystalline solid which has an onset of melting in the range 176.5-180.5 ⁰C, more particularly an onset of melting in the range 177.5-179.5 ⁰C and especially an onset of meting of approximately 178.5 ⁰C. In a further embodiment, Form 1 F may be characterised as a crystalline solid which has an enthalpy of melting in the range of 50-57 J/g, more particularly an enthalpy of melting in the range of 52-55 J/g and especially and an enthalpy of melting of approximately 53.6 J/g as measured by DSC. In another embodiment, Form 1 F may be characterised as a crystalline solid which provides a DSC thermogram substantially in accordance with

Figure 3c.

In one embodiment, Form 1 F may be characterised as a crystalline solid which provides a TGA thermogram substantially in accordance with Figure 3d.

Potassium salts

In one aspect, the invention provides a potassium salt of the compound of Formula I. In a further aspect, the invention provides a potassium salt of the compound of Formula I in the form of a crystalline solid. In another aspect, the invention provides a hydrated potassium salt of the compound of Formula 1 in the form of a crystalline solid. In yet another aspect, the invention provides a non-solvated (anhydrous) potassium salt of the compound of Formula 1 in the form of a crystalline solid. Crystalline forms of the posassium salt of the compound of Formula I may be characterized and differentiated using a number of conventional analytical techniques, including but not limited to X-ray powder diffraction (XRPD), Raman spectroscopy, differential scanning calorimetry (DSC) and solid state NMR.

In one aspect, the invention provides a hydrated potassium salt of the compound of Formula I in the form of a crystalline solid (Form 1G).

In one embodiment, Form 1 G may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 4a. In a further embodiment, Form 1 G may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 4a, wherein the data was obtained using a diffracted beam monochromator equipped with a suitable detector (such as the PANalytical X'Pert Pro diffractometer equipped with an X'Celerator detector) using Cu K-alpha (1.5406 A) radiation. In another embodiment, the sample is flattened on a zero-background silicon holder and is run immediately after preparation under ambient conditions, a continuous 2-theta scan range of 2° to 50° is used with a Cu K-alpha (1.5406 A) radiation source and a generator power of 45 kV and 40 mA, and a step size of 0.0167 degrees per 2-theta step is used and the sample is rotated at 30 rpm.

Preferably, Form 1 G has the XRPD characteristics of at least one embodiment described above and also the features of at least one embodiment described below.

In one embodiment, Form 1 G may be characterised as a crystalline solid which has an onset of melting in the range 105.5-109.5 ⁰C, more particularly an onset of melting in the range 106.5-108.5 ⁰C and especially an onset of meting of approximately 107.5 ⁰C. In a further embodiment, Form 1 G may be characterised by an enthalpy of melting in the range of 76-83 J/g, more particularly an enthalpy of melting in the range of 78-81 J/g and especially and an enthalpy of melting of approximately 79.7 J/g as measured by DSC. In another embodiment, Form 1 G may be characterised as a crystalline solid which provides a DSC thermogram substantially in accordance with Figure 4b.

In one embodiment, Form 1 G may be characterised as a crystalline solid which provides a TGA thermogram substantially in accordance with Figure 4c.

In another aspect, the invention provides an anhydrous potassium salt of the compound of Formula I in the form of an crystalline solid (Form 2G). In one embodiment, Form 2G may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) spectrum comprising 2 theta angle peaks at the positions, for example at 5% or greater relative intensity, set out in Table 4 to ±0.2°:

Table 4

In one embodiment, Form 2G may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 5a. In another embodiment, Form 2G may be characterised as a crystalline solid which provides an X-ray powder diffraction (XRPD) pattern substantially in accordance with Figure 5a, wherein the data was obtained using a diffracted beam monochromator equipped with a suitable detector (such as the PANalytical X'Pert Pro diffractometer equipped with an X'Celerator detector) using Cu K-alpha (1.5406 A) radiation. In a further embodiment, the sample is flattened on a zero-background silicon holder and is run immediately after preparation under ambient conditions, a continuous 2-theta scan range of 2° to 50° is used with a Cu K-alpha (1.5406 A) radiation source and a generator power of 45 kV and 40 mA, and a step size of 0.0167 degrees per 2-theta step is used and the sample is rotated at 30 rpm.

In one embodiment, Form 2G may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum at essentially: 596, 784, 817, 1161 , 1206, 1297, 1615, 2940, 3079 cm^"1 to ±6 cm^"1, preferably to ±4 cm^"1. In a further embodiment, Form 2G may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum substantially in accordance with Figure 5b. In a further embodiment, Form 2G may be characterised as a crystalline solid which provides bands on the FT-Raman spectrum at essentially: 596, 784, 817, 1 161 , 1206, 1297, 1615, 2940, 3079 cm^"1 to ±6 cm^"1, preferably to ±4 cm^"1and/or which provides bands on the FT-Raman spectrum substantially in accordance with Figure 5b wherein Raman spectra are recorded on a Nicolet NXR 9650 FT-Raman Spectrometer, at 4 cm^"1 resolution with excitation from a Nd: YV04 laser (λ = 1064 nm).

Preferably, a crystalline solid of Form 2G may be characterised by both of the above analytical techniques. Advantageously, Form 2G combines the XRPD characteristics of at least one embodiment described above with the FT-Raman characteristics for at least one embodiment described above. In one aspect of the invention, the crystalline solid of Form 2G may, additionally, have the characteristics of any one or more of the embodiments described below.

In one embodiment, Form 2G may be characterised by an onset of melting in the range 185-189 ⁰C, more particularly an onset of melting in the range 186.0-188.0 ⁰C and especially an onset of meting of approximately 187.1 ⁰C. In a further embodiment, Form 2G may be characterised by an enthalpy of melting in the range of 45-52 J/g, more particularly an enthalpy of melting in the range of 47-49 J/g and especially and an enthalpy of melting of approximately 48.4 J/g as measured by DSC. . In another embodiment, Form 2G may be characterised as a crystalline solid which provides a DSC thermogram substantially in accordance with Figure 5c. In one embodiment, Form 2G may be characterised as a crystalline solid which provides a TGA thermogram substantially in accordance with Figure 5d.

Compounds of the invention

The invention includes within its scope the free acid of the compound of Formula I and all possible stoichiometric and non-stoichiometric forms of the salts of the compound of Formula I.

The compounds of the invention may exist as solids or liquids, both of which are included in the invention. In the solid state, the compounds of the invention may exist as either amorphous material or in crystalline form, or as a mixture thereof. It will be appreciated that pharmaceutically acceptable solvates of compounds of Formula I and salts thereof may be formed wherein solvent molecules are incorporated into the crystalline lattice during crystallisation. Solvates may involve non-aqueous solvents such as ethanol, isopropanol, dimethylsulfoxide (DMSO), acetic acid, ethanolamine, and ethyl acetate, or they may involve water as the solvent that is incorporated into the crystalline lattice. Solvates wherein water is the solvent that is incorporated into the crystalline lattice are typically referred to as "hydrates." The invention includes all such solvates and the term "a compound of Formula I and salts thereof" or the like is to be understood as encompassing the solvated and the non-solvated compound and solvated and non- solvated salts thereof. It will be appreciated that compounds of the invention can exist in different tautomeric forms. In particular, the compound of Formula I may exist in the 4-pyridinol tautomeric form as follows:

All possible tautomeric forms of the compound of Formula I are contemplated to be within the scope of the present invention. In one aspect of the invention there is provided the compound of Formula I in the 4-pyridone tautomeric form. In another aspect of the invention there is provided the compound of Formula I in the 4-pyridinol tautomeric form. In a further aspect of the invention there is provided a mixture of the compound of Formula I in the 4-pyridone and 4-pyridinol tautomeric forms. In a yet further aspect of the invention, the mixture of 4-pyridone and 4-pyridinol tautomeric forms of the compound of Formula I is an equilibrium mixture.

Since the compounds of the invention are amphoteric it will be appreciated that they may be present in various zwitterionic forms in which the overall charge of the molecule is neutral but which carry formal negative and positive charges on certain atoms. For example, one of the hydroxide groups on the phosphate group may be deprotonated and thus carry a formal negative charge and the nitrogen atom may be protonated and thus carry a formal positive charge. The amphoteric compounds of the invention may for example exist as different equilibrium mixtures of zwitterionic forms depending on the polarity and pH of their environment. All possible zwitterionic forms of the compounds of Formula I are contemplated to be within the scope of the present invention.

It will also be appreciated that compounds of the invention that exist as polymorphs and mixtures thereof are all contemplated to be within the scope of the present invention.

As used herein, the term "compounds of the invention" means the compound according to Formula I and the salts thereof. The term "a compound of the invention" means any one of the compounds of the invention as defined herein. For the avoidance of doubt, the phrase "a compound according to Formula I" as used herein encompasses a compound of Formula I in either the 4-pyridone or 4-pyridinol tautomeric form or a mixture of tautomeric forms and also encompasses the compounds as a zwitterionic form or mixture of zwitterionic forms. For the avoidance of doubt the phrase "a compound of Formula I or a pharmaceutically acceptable salt thereof" as used herein encompasses a compound of Formula I as a free acid, a pharmaceutically acceptable solvate of the free acid of Formula I, a pharmaceutically acceptable salt of a compound of Formula I, and a pharmaceutically acceptable solvate of a pharmaceutically acceptable salt of a compound of Formula I. For the avoidance of doubt the term "free acid" as used herein means a compound of Formula I, including all tautomeric and zwitterionic forms, that is not deprotonated and has no overall charge.

The term "a crystalline form of the invention" means a crystalline form of a compound of the invention that is described herein. Such crystalline forms of the invention are characterised and differentiated from other crystalline forms of the same compound using a number of conventional analytical techniques, including but not limited to X-ray powder diffraction (XRPD), Raman spectroscopy, differential scanning calorimetry (DSC) and solid-state nuclear magnetic resonance spectroscopy (NMR).

Advantageously, compounds of the invention may have a high solubility in aqueous media and desirable pharmacokinetic profile in terms of high oral bioavailability and oral exposure from solid dosage forms. In one embodiment, certain compounds and, in particular, certain crystalline forms of the invention may have an improved solubility in aqueous media and/or better pharmacokinetic profile in terms of higher oral bioavailability and oral exposures from solid dosage forms than 3-chloro-6-(hydroxymethyl)-2-methyl-5- [4-({4-[(trifluoromethyl)oxy] phenyl}oxy)phenyl]-4(1 H)-pyridinone. A better pharmacokinetic profile may also lead to a reduction of the dose required to achieve the desired pharmacological effect, which may also have an impact on the cost of the treatments. An improved solubility in aqueous media may lead to a greater potential for parenteral administration and thus provide a more effective treatment for complicated malaria.

Methods

In one aspect, the invention provides a method of making the compound according to Formula I and salts thereof. In particular, the invention provides a method of making the compound according to Formula I and salts thereof comprising the step of combining 3- chloro-6-(hydroxymethyl)-2-methyl-5-[4-({4-[(trifluoromethyl) oxy]phenyl}oxy)phenyl]- 4(1 H)-pyridinone with tetrabenzyl pyrophosphate in the presence of lithium hydride and a hindered alcohol, such as te/f-butanol, in a suitable solvent such as tetrahydrofuran optionally under anhydrous conditions, to form {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate. In one aspect the hindered alcohol is a branched (that is a non-linear) C₃ to C₈ alcohol, for example a branched C₃ to C₆ alcohol. The hindered alcohol may, for example, be a secondary or a tertiary alcohol. In one embodiment, the hindered alcohol is a tertiary alcohol. Advantageously, the hindered alcohol provides a basic, non-nucleophilic, alkoxide ion on deprotonation with a base such as a metal hydride or by reaction with an alkali metal. Representative hindered alcohols include the tertiary alcohols te/f-butanol and tert- amyl alcohol (2-methyl-butan-2-ol); the secondary alcohols 3-pentanol and cyclohexanol; and the primary alcohol neopentyl alcohol (2,2-dimethyl-1-propanol). It has been found by the present inventors that preparation of 5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy) phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate by such a method provides the monophosphorylated derivative with selective phosphorylation of the primary alcohol. Alternative routes were found to result in relatively high proportions of a diphosphorylated derivative arising from phosphorylation of the alcohol present at the 3-position of the pyridine ring in the 4-pyridinol tautomeric form requiring a hydrolysis step to prepare the desired monophosphorylated compound ({5- chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2- pyridinyljmethyl bis(phenylmethyl) phosphate).

As used herein the term "selective phosphorylation" and "selectively phophorylated" refers to a phosphorylation reaction that provides a ratio of at least 4:1 of a product phosphorylated solely at the primary alcohol of the 6-hydroxymethyl group of 3-chloro-6- (hydroxymethyl)-2-methyl-5-[4-({4-[(trifluoromethyl) oxy]phenyl}oxy)phenyl]-4(1 H)- pyridinone, to products phosphorylated at the secondary alcohol of the 4-pyridinol tautomeric form, including a product monophosphroylated at the secondary alcohol of the 4-pyridinol tautomeric form and a diphosphorylated derivative. Preferably, selective phosphorylation of the primary alcohol provides a ratio of at least 9:1 , especially at least 19:1 of a product phosphorylated solely at the primary alcohol to products phosphorylated at the secondary alcohol.

In one aspect the invention provides {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate. Monophosphorylated compound {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate is useful in the preparation of the compounds of formula I and salts thereof.

{5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2- pyridinyl}methyl bis(phenylmethyl) phosphate can be converted to the compound according to Formula I and salts thereof by standard techniques. For example, {5-chloro-

6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2- pyridinyl}methyl bis(phenylmethyl) phosphate can be deprotected using the methods described in, for example, "Protective groups in organic synthesis" by T. W. Greene and P. G. M. Wuts (John Wiley & sons 1991 ) or "Protecting Groups" by PJ. Kocienski (Georg

Thieme Verlag 1994). Deprotection of the phenylmethyl protecting groups by hydrogenation was found to be the preferred method. Although deprotection of the hydroxymethyl group from {5-chloro-6-methyl-4-oxo-3-[4-({4-

[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate using standard techniques met with some success, the present inventors have developed alternative methods for the removal of the benzyl group which have been found to be particulary advantageous in the preparation of compounds of Formula I.

In one aspect, the invention provides a method of making a compound of Formula I in which the benzyl protecting group is removed by treating {5-chloro-6-methyl-4-oxo-3-[4- ({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate with 1 ,4-cyclohexadiene, in the presence of a hydrogenation catalyst, such as Pd on charcoal, in a suitable solvent, such as a mixture of methanol/dichloromethane, for example an approximately 3:1 mixture of methanol/dichloromethane.

In a further aspect, the invention provides a method of making a compound of Formula I in which the benzyl protecting group is removed by treating {5-chloro-6-methyl-4-oxo-3-[4- ({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate with formic acid in the presence of a hydrogenation catalyst, such as Pd on charcoal, in a suitable solvent, such as tetrahydrofuran. In one embodiment, Pd on charcoal moistened with water is used as a hydrogenation catalyst, for example approximatelty 10% Pd on charcoal moistened with water. Removal of the benzyl protecting group using hydrogenation in the presence of formic acid has been found to be particularly advantageous on a large scale and may also reduce the amount of benzene by-products produced compared with other methods.

Form 1A of {5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl dihydrogen phosphate can be prepared by recrystallising the amorphous free acid using acetonitrile as a solvent. Form 1 C of the tromethamine salt of {5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2- pyridinyl}methyl dihydrogen phosphate can be obtained by the portionwise addition of tromethamine to a slurry of the free acid in acetone. Form 1 F of the sodium salt of {5- chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2- pyridinyl}methyl dihydrogen phosphate can be obtained by the addition of an aqueous solution of sodium hydroxide to a slurry of the free acid in acetonitrile. Form 1 G of the potassium salt of {5-chloro-6-methyl-4-oxo-3-[4-({4-

[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate can be obtained by the addition of an aqueous solution of potassium hydroxide to a slurry of the free acid in acetonitrile. Form 2G of the potassium salt of {5-chloro-6- methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2- pyridinyl}methyl dihydrogen phosphate can be obtained by drying form 1 G. The processes for the preparation of the crystalline forms of the present invention also show a high degree of robustness, an advantage for a highly regulated compound. Batches of the crystalline forms can, by the processes of this invention, be made consistently to a high crystal form purity i.e., where the proportion of crystalline forms of {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl dihydrogen phosphate and isalts thereof other than the desired form are limited (particularly less than 20%).

Uses of compounds of the invention

According to one aspect of the invention there is provided a compound of Formula I or a pharmaceutically acceptable salt thereoffor use in human or veterinary medical therapy. According to a further aspect of the invention there is provided a crystalline solid of a compound of Formula I or a pharmaceutically acceptable salt thereof for use in human or veterinary medical therapy. According to another aspect of the invention there is provided a crystalline form of the invention for use in human or veterinary medical therapy.

The compounds and crystalline forms of the invention can be useful in the treatment of certain parasitic infections such as parasitic protozoal infections by the malarial parasite Plasmodium falciparum, species of Eimeria, Pneumocytis carinii, Trypanosoma cruzi, Trypanosoma brucei or Leishmania donovani. In particular, the compounds and crystalline forms of the invention can be useful for treatment of infection by Plasmodium falciparum. Accordingly, the invention is directed to methods of treating such conditions.

In one aspect of the invention, there is provided a compound of Formula I or a pharmaceutically acceptable salt thereof, for use in therapy, for example the treatment of parasitic protozoal infections such as malaria, for example infection by Plasmodium falciparum. In a further aspect of the invention, there is provided a crystalline solid of a compound of Formula I or a pharmaceutically acceptable salt thereof, for use in therapy, for example the treatment of parasitic protozoal infections such as malaria, for example infection by Plasmodium falciparum. In another aspect of the invention, there is provided a crystalline form of the invention, for use in therapy, for example the treatment of parasitic protozoal infections such as malaria, for example infection by Plasmodium falciparum.

In one aspect of the invention, there is provided the use of a compound of Formula I or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for the treatment of parasitic protozoal infections such as malaria, for example a condition caused by infection by Plasmodium falciparum. In a further aspect of the invention, there is provided the use of a crystalline solid of a compound of Formula I or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for the treatment of parasitic protozoal infections such as malaria, for example a condition caused by infection by Plasmodium falciparum. In another aspect of the invention, there is provided the use of a crystalline form of the invention in the manufacture of a medicament for the treatment of parasitic protozoal infections such as malaria, for example a condition caused by infection by Plasmodium falciparum. In one aspect of the invention there is provided a method for the treatment of a human or animal subject suffering from a parasitic protozoal infection such as malaria, for example infection by Plasmodium falciparum, comprising administering to said human or animal subject an effective amount of a compound of Formula I or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition comprising a compound of Formula I or a pharmaceutically acceptable salt thereof. In a further aspect of the invention there is provided a method for the treatment of a human or animal subject suffering from a parasitic protozoal infection such as malaria, for example infection by Plasmodium falciparum, comprising administering to said human or animal subject an effective amount of a crystalline solid of a compound of Formula I or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition comprising a crystalline solid of a compound of Formula I or a pharmaceutically acceptable salt thereof. In another aspect of the invention there is provided a method for the treatment of a human or animal subject suffering from a parasitic protozoal infection such as malaria, for example infection by Plasmodium falciparum, comprising administering to said human or animal subject an effective amount of a crystalline form of the invention, or a pharmaceutical composition comprising a crystalline form of the invention.

The methods of treatment of the invention comprise administering a safe and effective amount of a compound according to Formula I or a pharmaceutically acceptable salt thereof, or administering a safe and effective amount of a crystalline form of the invention, to a patient in need thereof.

As used herein, "treatment" means: (1 ) the amelioration or prevention of the condition being treated or one or more of the biological manifestations of the condition being treated, (2) the interference with (a) one or more points in the biological cascade that leads to or is responsible for the condition being treated or (b) one or more of the biological manifestations of the condition being treated, or (3) the alleviation of one or more of the symptoms or effects associated with the condition being treated. The skilled artisan will appreciate that "prevention" is not an absolute term. In medicine, "prevention" is understood to refer to the prophylactic administration of a drug to substantially diminish the likelihood or severity of a condition or biological manifestation thereof, or to delay the onset of such condition or biological manifestation thereof.

As used herein, "safe and effective amount" means an amount of the compound sufficient to significantly induce a positive modification in the condition to be treated but low enough to avoid serious side effects (at a reasonable benefit/risk ratio) within the scope of sound medical judgment. A safe and effective amount of a compound of the invention will vary with the particular compound chosen (e.g. depending on the potency, efficacy, and half- life of the compound); the route of administration chosen; the nature of the infection and/or condition being treated; the severity of the infection and/or condition being treated; the age, size, weight, and physical condition of the patient being treated; the medical history of the patient to be treated; the duration of the treatment; the nature of concurrent therapy; the desired therapeutic effect; and like factors, but can nevertheless be routinely determined by the skilled artisan.

As used herein, "patient" refers to a human or other animal.

The compounds and crystalline forms of the invention may be administered by any suitable route of administration, including systemic administration. Systemic administration includes oral administration, parenteral administration, transdermal administration, rectal administration, and administration by inhalation. Parenteral administration refers to routes of administration other than enteral, transdermal, or by inhalation, and is typically by injection or infusion. Parenteral administration includes intravenous, intramuscular, and subcutaneous injection or infusion. Inhalation refers to administration into the patient's lungs whether inhaled through the mouth or through the nasal passages. Topical administration includes dermal application to the skin as well as intraocular, buccal (e.g. sub-lingually), rectal, intravaginal, and intranasal administration.

The compounds and crystalline forms of the invention may, for example, be particularly suited to parenteral administration due to their water solubility.

The compounds and crystalline forms of the invention may be administered once only, or according to a dosing regimen wherein a number of doses are administered at varying intervals of time for a given period of time. For example, doses may be administered one, two, three, or four times per day. Doses may be administered until the desired therapeutic effect is achieved or indefinitely to maintain the desired therapeutic effect. The dosage will also vary according to the nature of the intended treatment, wherein "treatment" is as hereinbelow defined, for example a greater dose of compound may be given for amelioration as compared with prevention of a condition being treated. Suitable dosing regimens for a compound of the invention depend on the pharmacokinetic properties of that compound, such as absorption, distribution, and half-life, which can be determined by the skilled artisan. In addition, suitable dosing regimens for a compound of the invention, including the duration such regimens are administered, depend on the route of administration of the compound, on the condition being treated, the severity of the condition being treated, the age and physical condition of the patient being treated, the medical history of the patient to be treated, the nature of any concurrent therapy, the desired therapeutic effect, and like factors within the knowledge and expertise of the skilled artisan. It will be further understood by such skilled artisans that suitable dosing regimens may require adjustment given an individual patient's response to the dosing regimen or over time as individual patient needs change. It will also be appreciated that if the compounds of the present invention are administered in combination with one or more additional active therapeutic agents as discussed further hereinbelow, the dosing regimen of the compounds of the invention may also vary according to the nature and amount of the one or more additional active therapeutic agents as necessary.

Typical daily dosages may vary depending upon the particular route of administration chosen. Typical daily dosages for oral administration range from about 0.01 to about 30 mg/kg, for example, from about 0.01 to about 25 mg/kg, in one embodiment from about 0.1 to about 14 mg/kg. Typical daily dosages for parenteral administration range from about 0.001 to about 10 mg/kg; in one embodiment from about 0.01 to about 6 mg/kg. In one embodiment, the daily dose range of the compounds is from 100-1000 mg per day.

The compounds and crystalline forms of the invention also be used in combination with other active therapeutic agents. The invention thus provides, in a further aspect, a combination comprising a compound or a crystalline form of the invention together with further active therapeutic agents. When a compound or crystalline form of the invention is used in combination with a second active therapeutic agent which is active against the same disease state the dose of each compound may differ from that when the compound is used alone. Appropriate doses will be readily appreciated by those skilled in the art. It will be appreciated that the amount of a compound of the invention required for use in treatment will vary with the nature of the condition being treated and the age and the condition of the patient and will be ultimately at the discretion of the attendant physician or veterinarian.

The compounds and crystalline forms of the present invention may be used alone or in combination with one or more additional active therapeutic agents, such as other antiparasitic drugs, for example antimalarial drugs. Such other active therapeutic agents include antimalarial drugs, such as folates (e.g. chloroquine, mefloquine, primaquine pyrimethamine, quinine, artemisinin, halofantrine, doxycycline, amodiquine, atovaquone, tafenoquine) and antifolates (e.g. dapsone, proguanil, sulfadoxine, pyrimethamine, chlorcycloguanil, cycloguanil).

The combinations referred to above may conveniently be presented for use in the form of a pharmaceutical formulation and thus pharmaceutical formulations comprising a combination as defined above together with a pharmaceutically acceptable carrier and/or excipient comprise a further aspect of the invention. The individual components of such combinations may be administered either sequentially or simultaneously in separate or combined pharmaceutical formulations by any convenient route.

When administration is sequential, either the compound or crystalline forms of the present invention or the one or more additional active therapeutic agent(s) may be administered first. When administration is simultaneous, the combination may be administered either in the same or different pharmaceutical composition. When combined in the same formulation it will be appreciated that the compound of the present invention and the one or more additional active therapeutic agent(s) must be stable and compatible with each other and the other components of the formulation. When formulated separately the compound or crystalline form of the present invention and the one or more additional active therapeutic agent(s) may be provided in any convenient formulation, conveniently in such manner as are known for such compounds in the art.

Compositions The compounds and crystalline forms of the invention will normally, but not necessarily, be formulated into pharmaceutical compositions prior to administration to a patient. In one aspect, the invention is directed to pharmaceutical compositions comprising a compound or crystalline form of the invention. In another aspect the invention is directed to a pharmaceutical composition comprising a compound or crystalline form of the invention and one or more pharmaceutically acceptable carriers and/or excipients.

The carrier and/or excipient must be "acceptable" in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipient thereof.

The pharmaceutical compositions of the invention may be prepared and packaged in bulk form wherein a safe and effective amount of a compound of the invention can be extracted and then given to the patient such as with powders or syrups. Alternatively, the pharmaceutical compositions of the invention may be prepared and packaged in unit dosage form wherein each physically discrete unit contains a safe and effective amount of a compound of the invention. When prepared in unit dosage form, the pharmaceutical compositions of the invention typically contain from about 0.1 to 1000 mg, in another aspect 0.1 mg to about 500 mg of a compound of the invention.

The pharmaceutical compositions of the invention typically contain one compound or crystalline form of the invention. However, in certain embodiments, the pharmaceutical compositions of the invention contain more than one compound or crystalline form of the invention. For example, in certain embodiments the pharmaceutical compositions of the invention contain two compounds of the invention. In addition, the pharmaceutical compositions of the invention may optionally further comprise one or more additional active therapeutic compounds. The pharmaceutical compositions of the invention typically contain more than one pharmaceutically acceptable excipient. However, in certain embodiments, the pharmaceutical compositions of the invention contain one pharmaceutically acceptable excipient. As used herein, the term "pharmaceutically acceptable" means suitable for pharmaceutical use.

The compound or crystalline form of the invention and the pharmaceutically acceptable excipient or excipients will typically be formulated into a dosage form adapted for administration to the patient by the desired route of administration. For example, dosage forms include those adapted for (1 ) oral administration such as tablets, capsules, caplets, pills, troches, powders, granules, syrups, elixirs, suspensions, solutions, emulsions, sachets, and cachets; (2) parenteral administration such as sterile solutions, suspensions, and powders for reconstitution; (3) transdermal administration such as transdermal patches; (4) rectal administration such as suppositories; (5) inhalation such as aerosols and solutions; and (6) topical administration such as creams, ointments, lotions, solutions, pastes, sprays, foams, and gels. In one aspect of the invention, the compound or crystalline form of the invention is formulated as a dosage form for parenteral administration. In one aspect of the invention, the compound or crystalline form of the invention is formulated into a solution dosage form or a solid (e.g. a powder) for reconstitution into a solution dosage form.

Suitable pharmaceutically acceptable excipients will vary depending upon the particular dosage form chosen. In addition, suitable pharmaceutically acceptable excipients may be chosen for a particular function that they may serve in the composition. For example, certain pharmaceutically acceptable excipients may be chosen for their ability to facilitate the production of uniform dosage forms. Certain pharmaceutically acceptable excipients may be chosen for their ability to facilitate the production of stable dosage forms. Certain pharmaceutically acceptable excipients may be chosen for their ability to facilitate the carriage or transport of the compound or compounds of the invention from one organ, or portion of the body, to another organ, or portion of the body, once administered to the patient. Certain pharmaceutically acceptable excipients may be chosen for their ability to enhance patient compliance. Certain pharmaceutically acceptable excipients may be chosen for their ability to impart a controlled release of the active drug(s) agents for a desired pharmacokinetic profile.

Suitable pharmaceutically acceptable excipients include the following types of excipients: binders, disintegrants, lubricants, glidants, granulating agents, coating agents, wetting agents, solvents, co-solvents, suspending agents, emulsifiers, sweeteners, flavouring agents, flavour masking agents, coloring agents, anticaking agents, humectants, chelating agents, plasticizers, viscosity increasing agents, antioxidants, preservatives, stabilizers, surfactants, and buffering agents. The skilled artisan will appreciate that certain pharmaceutically acceptable excipients may serve more than one function and may serve alternative functions depending on how much of the excipient is present in the formulation and what other ingredients are present in the formulation. Skilled artisans possess the knowledge and skill in the art to enable them to select suitable pharmaceutically acceptable excipients in appropriate amounts for use in the invention. In addition, there are a number of resources that are available to the skilled artisan which describe pharmaceutically acceptable excipients and may be useful in selecting suitable pharmaceutically acceptable excipients. Examples include Remington's Pharmaceutical Sciences (Mack Publishing Company), The Handbook of Pharmaceutical Additives (Gower Publishing Limited), and The Handbook of Pharmaceutical Excipients (the American Pharmaceutical Association and the Pharmaceutical Press).

The pharmaceutical compositions of the invention are prepared using techniques and methods known to those skilled in the art. Some of the methods commonly used in the art are described in Remington's Pharmaceutical Sciences (Mack Publishing Company).

In one aspect, the invention is directed to a liquid dosage form for oral administration, comprising a safe and effective amount of a solution or suspension of a compound of the invention and a liquid carrier, for example, ethanol, olive oil, glycerine, glucose (syrup) or water (e.g. with an added flavouring, suspending, or colouring agent) or those described in The Handbook of Pharmaceutical Excipients (the American Pharmaceutical Association and the Pharmaceutical Press.

In one aspect, the invention is directed to a liquid dosage for injection or infusion, comprising a safe and effective amount of a solution of a compound of the invention and a liquid carrier, for example, water (e.g. with an added sodium chloride). In one aspect, the invention is directed to an injectable solution.

In one aspect, the invention is directed to a solid for reconstitution into a liquid dosage form.

In one aspect the invention is directed to a pharmaceutical compositions comprising solid particles that comprise a compound or crystalline form of the invention, said solid particules having a reduced particle size, for example, a particle size with an average (mean) maximum dimension of from 0.01 to 100 microns. In one embodiment, the compound or crystalline form is present as a consitutent of a solid particle, said solid particle having an average (mean) maximum dimension of from 0.01 to 100 microns. The term "maximum dimension" refers to the longest distance in a straight line between two farthest points on the particle

Abbreviations In describing the invention, chemical elements are identified in accordance with the Periodic Table of the Elements. Abbreviations and symbols utilised herein are in accordance with the common usage of such abbreviations and symbols by those skilled in the chemical arts. The following abbreviations are used herein:

AcOEt, EtOAc ethyl acetate approx. approximately brine saturated aqueous sodium chloride cone. concentrated

DMSO dimethylsulfoxide

DMSO-d₆ deuterated dimethylsulfoxide

CP-MAS cross polarization magic angle spinning

CP-TOSS cross polarization total sideband surpression

ES MS electrospray mass spectrometry

FaSSIF fasted state simulated intestinal fluid

FeSSIF fed state simulated intestinal fluid

Gl gastrointestinal h hour(s)

HPLC high performance liquid chromatography

L litre(s)

LC-MS liquid chromatography-mass spectrometry min. minute(s)

NaTaurochol. sodium Taurocholic

PBS phosphate buffered saline

PH -Log-io of the hydrogen ion concentration pK_a -Log-io of the acid dissociation constant

RT room temperature

SGF simulated gastric fluid v/v volume ratio w/w weight ratio, e.g. percentage by weight

Analytical techniques

X-ray powder diffraction (XRPD) data were obtained using a PANalytical X'Pert Pro diffractometer equipped with an X'Celerator detector. The sample was flattened on a zero-background silicon holder and was run immediately after preparation under ambient conditions. A continuous 2-theta scan range of 2° to 50° was used with a Cu K-alpha (1.5406 A) radiation source and a generator power of 45 kV and 40 mA. A step size of 0.0167 degrees per 2-theta step was used and the sample was rotated at 30 rpm. 2 Theta angles in degrees (x-axis) are plotted against peak intensity in terms of the count rate per seconds (y-axis). The XRPD pattern is unique to the particular form; exhibiting a unique set of diffraction peaks which can be expressed in 2 theta angles (°) or d-spacings (A). 2 Theta diffraction angles and corresponding d-spacing values account for positions of various peaks in the XRPD pattern, d-spacing values are calculated with observed 2 theta angles and copper Kα1 wavelength using the Bragg equation. Slight variations in observed 2 theta angles and d-spacings are expected based on the specific diffractometer employed and the analyst's sample preparation technique. Identification of the exact crystal form of a compound should be based primarily on observed 2 theta angles or d- spacings. Some margin of error is present in each of the 2 theta angle assignments and d-spacings reported herein and slight variations in the reported 2 theta angles and d- spacing values will be observed. The error in determining d-spacings decreases with increasing diffraction scan angle or decreasing d-spacing. The margin of error in the foregoing 2 theta angles is approximately ±0.1 degrees for each of the foregoing peak assignments. Thus, a crystalline form of a compound of the invention might be observed to have XRPD 2 theta angles to within ±0.1 °, or in some instances ±0.2°, of the angles reported herein. Since some margin of error is possible in the assignment of 2 theta angles and d-spacings, the preferred method of comparing XRPD patterns in order to identify the particular form of a sample of a compound is to overlay the XRPD pattern of the unknown sample over the XRPD pattern of a known form to confirm that the peaks are in substantially the same relative positons, taking into account the expected minor variations.

Raman spectra were recorded on a Nicolet NXR 9650 FT-Raman Spectrometer, at 4 cm^"1 resolution with excitation from a Nd: YV04 laser (λ = 1064 nm). Slight variations in observed Raman spectra peaks and based on the specific spectrometer employed and the analyst's sample preparation technique. Slight variations in the wavelength of Raman spectra peaks for different samples of a particular crystalline form are to be expected, since some margin of error is possible. Thus, a crystalline form of a compound of the invention might be observed to have the Raman bands reported herein to within ±4 cm^"1, or in some instances ±6 cm^"1. The preferred method of comparing Raman patterns in order to identify the particular form of a sample of a compound is to overlay the Raman pattern of the unknown sample over the Raman pattern of a known form to confirm that the bands are at substantially the same relative positions, taking into account the expected minor variations.

DSC thermograms were recorded on a TA Instruments Q100 Differential Scanning Calorimeter. The sample was weighed into an aluminium pan, a pan lid placed on top and lightly crimped without sealing the pan. The experiments were conducted using a heating rate of 15 °C/min. TGA thermograms were recorded on a TA Instruments Q5000 Thermogravimetric Analyzer. TGA-IR analysis was performed using TA Instruments Q500 Thermo Gravimetric Analyzer coupled with Nicolet 6700 FT-IR spectrometer. The sample was weighed into an aluminium pan, and experiments were conducted using a heating rate of 15 °C/min.

Solid-state ¹³C NMR spectra were acquired using a Bruker Avance 500 triple-resonance spectrometer operating at a ¹H frequency of 500.13 MHz. ¹³C NMR spectra were obtained using a cross-polarization pulse sequence with a Bruker 4-mm triple resonance magic-angle spinning probe at a rotor frequency of 8 kHz. A linear power ramp from 75 to 90 kHz was used on the ¹H channel to enhance cross-polarization efficiency. Spinning sidebands were eliminated by a five-pulse total sideband suppression (TOSS) pulse sequence. ¹⁹F spectra were obtained using the same spectrometer and probe, using a cross-polarization pulse sequence and spinning at a rotor frequency of 12.5 kHz. Characteristic ¹³C NMR peak positions are reported relative to tetramethylsilane at 0 ppm (parts per million) and are quoted to a precision of +/- 0.2 ppm, because of instrumental variability and calibration. ¹⁹F NMR peak positions are reported relative to CFCI₃ and are quoted to a precision of +/- 0.2 ppm, because of instrumental variability and calibration. ³¹P spectra were obtained using a Bruker Avance 400 triple-resonance spectrometer operating at a ¹H frequency of 399.87 MHz. A 2.5-mm double-resonance probe spinning at a rotor frequency of 25 kHz was used with a cross-polarization pulse sequence. ³¹P NMR peak positions are reported relative to CFCI₃ and are quoted to a precision of +/- 0.2 ppm, because of instrumental variability and calibration. All spectra were obtained at 273 K.

In addition, other methods of physical characterization can also be employed to identify and characterize the crystalline forms of the compound of Formula (I) and salts and solvates thereof of the invention. These additional techniques may be employed alone or in combination with one or more of the techniques described herein to characterize a sample of an unknown form of a crystalline solid of a compound of Formula (I) or a salt thereof.

An XRPD pattern "substantially" in accordance with a figure reproduced herein is an XRPD pattern having peaks attributable to the compound of interest at the same relative positions as those shown in said figure within the margins of error specified herein. The relative intensity of the peaks may vary.

An FT-Raman spectrum "substantially" in accordance with a figure reproduced herein is an FT-Raman spectrum having bands attributable to the compound of interest at the same relative positions as those shown in said figure within the margins of error specified herein. The relative intensity of the bands may vary. A DSC thermogram or a TGA thermogram "substantially" in accordance with a figure reproduced herein is a DSC thermogram or a TGA thermogram of the form shown in said figure with events at the same temperatures taking into account the variations in such thermograms expected in the art.

EXAMPLES

The following examples illustrate the invention. These examples are not intended to limit the scope of the invention, but rather to provide guidance to the skilled artisan to prepare and use the compounds, compositions, and methods of the invention. While particular embodiments of the invention are described, the skilled artisan will appreciate that various changes and modifications can be made without departing from the spirit and scope of the invention.

INTERMEDIATE A {5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate

Method A - Phosphorylation followed by hydrolysis of diphosphorylated derivatives

To a suspension of 20.0 g of 3-chloro-6-(hydroxymethyl)-2-methyl-5-[4-({4-[(trifluoro methyl)oxy]phenyl}oxy)phenyl]-4(1 H)-pyridinone (described in WO 2007/138048) in 600 ml of anhydrous tetrahydrofuran under argon atmosphere at 0 ⁰C was added 0.825 g of lithium hydride in one charge. The reaction mixture was stirred at 30 ⁰C for 3 h. This mixture was cooled down to 0 ⁰C and 34.1 g of tetrabenzyl pyrophosphate were added. This temperature was kept for 2 h and then reaction process was allowed to reach 30 ⁰C and stirred during the night. 16h later, starting material was still present so the temperature was cooled down to 0 ⁰C and an additional 0.196 g of lithium hydride was added. The reaction mixture was stirred at 30 ⁰C for 1 h. The reaction mixture was cooled down to 0 ⁰C, hydrolyzed with 400 ml of 1 N HCI and diluted with 700 ml of ethyl acetate. The organic phase was separated and then washed with 400 ml (x 3) of sodium carbonate 5% and 400 ml of water. Brine was added in order to obtain clear layers. Finally, the organic phase was washed with 400 ml of 1 N HCI and 400 ml of brine, dried over sodium sulphate, filtered and concentrated to dryness. The solid obtained was suspended in 160 ml of te/t-butyl methyl ether and stirred for 1 h to obtain a white solid which was then filtrated and washed with more tert-butyl methyl ether to afford 21.42 g of the title compound.

The resulting tert-butyl methyl ether solution was concentrated to dryness to leave 15.5 g of a colourless oil. This oil was dissolved in 240 ml of methanol and cooled to 0 ⁰C. 48 ml of 1 N NaOH was added dropwise and the mixture was allowed to reach room temperature and stirred for an additional 3 h. The reaction mixture was neutralized with 48 ml of 1 N HCI and then concentrated under vacuum to eliminate methanol. The crude mixture was dissolved in 250 ml of tetrahydrofuran and 300 ml of ethyl acetate and washed with 250 ml of 1 N HCI, 250 ml of sodium carbonate 5% and 250 ml of water. Brine was added in order to obtain clear layers. Finally, the organic phase was washed with 250 ml of 1 N HCI and 250 ml of brine, dried over sodium sulphate and evaporated in vacuo to give a solid. This solid was suspended in 60 ml of tert-butyl methyl ether and stirred for 1 h to obtain a precipitated which was filtrated and washed with more tert-butyl methyl ether to lead additional 9.32 g of the title compound.

¹H NMR (δ, ppm, DMSOd₆ ): 1 1.99 (s, 1 H); 7.40-7.16 (m, 14H); 7.14-7.03 (m, 2H); 7.02- 6.93 (m, 2H); 4.93 (d, 4H); 4.80 (d, 2H); 2.40 (s, 3H). ES MS m/z: 686 [M+H]⁺.

Method B - Selective phosphorylation to provide the monophosphorylated derivative

To a stirred suspension of 1 g of 3-chloro-6-(hydroxymethyl)-2-methyl-5-[4-({4-[(trifluoro methyl)oxy]phenyl}oxy)phenyl]-4(1 H)-pyridinone (described in WO 2007/138048) and 45 μl of te/f-butanol (dried over 4A molecular sieves) in 45 ml of anhydrous tetrahydrofuran at room temperature under argon atmosphere was added 45 mg of 95% lithium hydride portionwise. The mixture was warmed to 30 ⁰C and stirred vigorously under argon atmosphere overnight, then it was cooled to 0 ⁰C and 1.5 g of tetrabenzyl pyrophosphate was added. The reaction mixture was vigorously stirred at 0 ⁰C under argon for 2 h, then it was cautiously quenched with 20 ml of 1 N hydrochloric acid, warmed to room temperature and partitioned between ethyl acetate (75 ml) and water (75 ml). The layers were separated and the organic layer was washed with aqueous 5% Na₂CO₃ (3x75 ml), water (75 ml), 1 N HCI (75 ml) and brine (75 ml), dried (Na₂SO₄), filtered and concentrated near to dryness under reduced pressure to give a paste which was triturated with tert-butyl methyl ether (30 ml) for 5 h. The solid was filtered off, washed with te/t-butyl methyl ether (2x10 ml) and dried under vacuum to give 1.46 g of the title compound as a white solid.

¹H NMR (δ, ppm, DMSO-d₆ ): 1 1.99 (s, 1 H); 7.39-7.15 (m, 14H); 7.09 (d, 2H); 6.98 (d, 2H); 4.93 (d, 4H); 4.80 (d, 2H); 2.40 (s, 3H). ES MS m/z: 686 (MH+) EXAMPLE 1

{5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl dihydrogen phosphate

Amorphous free acid

Method A: Hydrogenolysis using 1 ,4-cyclohexadiene

Batch (i) - 27.9 g of 10% Palladium on activated charcoal was added under an argon atmosphere to a solution of 180 g of Intermediate A and 186 ml of 1 ,4-cyclohexadiene in 4 L of a 3:1 mixture methanol/dichloromethane at 15 ⁰C. The reaction mixture was warmed to 25 ⁰C and stirred under argon for 2 h. The solids were removed by filtration through a celite pad washing with 1 L of methanol and the filtrate evaporated to dryness to give a solid which was triturated with 1.5 L of te/t-butyl methyl ether. The resulting solid was filtered, washed with 300 ml (x 3) of te/f-butyl methyl ether and dried under vacuum at 35 ⁰C overnight to give 1 19.95 g of the title compound as an amorphous white solid.

Batch (ii) - To a solution of Intermediate A (69 mg, 0.1 mmol) and 1 ,4-cyclohexadiene (0.5 ml, 5.3 mmol) in methanol (10 ml) under nitrogen was added 10% palladium on activated charcoal (10 mg) and the mixture was stirred at room temperature under a nitrogen atmosphere. After 4 h the reaction was filtered through a 25 mm syringe filter (Nylon 0.45 μm) and the filtrate evaporated to dryness to give a solid which was co-evaporated with dichloromethane. The resulting white solid (50 mg) was triturated with dichloromethane (3 ml) and the solid was filtered, washed with dichloromethane (2 ml) and dried under vacuum to yield 33 mg of the title compound as a white solid. A crystallinity study on the product obtained in Method A, Batch (ii) was not performed.

Method B: Hydrogenolysis using formic acid

To a solution of Intermediate A (1 g, 1.46 mmol) in tetrahydrofuran (45 ml) under a nitrogen atmosphere was added formic acid (5 ml) followed by 10% palladium on activated charcoal moistened with water (0.4 g, it contains -50% water) and the reaction mixture was stirred at 67 ⁰C (bath temperature) under nitrogen for 3h. Additional 10% Pd on activated charcoal moistened with water (0.2 g, it contains -50% water) was added and the mixture stirred at 67 ⁰C under nitrogen for 3 h. The reaction mixture was left in the bath to reach room temperature overnight. The solids were removed by filtration through a celite pad washing with 9:1 THF/HCO₂H (2x10 ml) and then THF (2x10 ml) and the filtrates were combined and evaporated to dryness. The crude obtained was co- evaporated with toluene (2x15 ml) and te/f-butyl methyl ether (10 ml) to give 0.785 g of solid which was treated with tetrahydrofuran (15 ml) and stirred at room temperature overnight. The solid was filtered, washed with tetrahydrofuran (2x5 ml) and dried under vacuum at 40 ⁰C over the weekend to yield 0.576 g of the title compound as a white solid. A crystallinity study on the product obtained in Method B was not performed.

¹H NMR (δ, ppm, DMSOd₆ ): 11.75 (bs, 1 H); 7.40 (d, 2H); 7.25 (d, 2H); 7.16 (d, 2H); 7.04 (d, 2H); 4.62 (d, 2H); 2.43 (s, 3H). ES MS m/z: 506 (MH+).

Crystalline Solid - Form 1A

Acetonitrile (32.0 ml.) was added to the amorphous free-acid (3.2 g, 6.35 mmole). The suspension was heated to 55 ⁰C, which produced a partially crystalline solid with a glassy layer at the bottom of the reactor. Heating was continued at 55 ⁰C for 15 hours with constant stirring and resulted in a white solid. The mixture was cooled while stirring at 0.1 °C/min to 20 ⁰C and held for 5 hours. The solid was isolated by filtration, washed with acetonitrile (3 x 2.5 ml.) and dried overnight in a vacuum oven at 50 ⁰C to yield of the non- solvated crystalline free-acid (2.8 g, 87.1%).

¹³C solid-state NMR (δ, ppm): 170.6, 167.9, 156.5, 155.1 , 153.3, 152.8, 149.9, 148.1 , 146.1 , 145.6, 143.5, 142.5, 135.9, 133.2, 132.5, 131.2, 127.0, 124.5, 122.3, 119.3, 117.6, 116.9, 1 15.1 , 114.0, 62.6, 61.5, 19.5, 17.3; ¹⁹F solid-state NMR (δ, ppm): -54.5; ³¹P solid- state NMR (δ, ppm): -0.3, -1.4. The ¹³C, ¹⁹F and ³¹P solid-state NMR specta for Form 1A are shown in Figure 1 e, Figure 1f and Figure 1g respectively.

The solid-state NMR for Form 1 A indicates that crystal structure contains two magnetically inequivalent molecules in each unit cell that are not symmetry-related.

The X-ray powder diffraction pattern, Raman spectrum, DSC thermal data and TGA thermal data for Form 1A are shown in Figure 1 a, Figure 1 b, Figure 1c, and Figure 1 d respectively.

Characteristic XRPD angles and d-spacing values for Form 1A are as follows:

Peaks marked "^*" were considered to be more characteristic of the Form 1 A than the remaining peaks.

Bands on the FT-Raman spectrum (Fig. 1 b) were observed at: 593, 818, 854, 1 166, 1215, 1612, 2946, 3076 cm^"1 for Form 1A.

An event with an onset at 163.3 ⁰C and enthalpy of 59.3 J/g was observed in the DSC for Form 1A (Fig. 1c).

An event at 34 ⁰C to 68.7 ⁰C resulting in the loss of 0.01% w/w followed by a decompoisiton event above 150 ⁰C was obsereved in the TGA of Form 1A (Fig. 1d).

EXAMPLE 2 {5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl dihydrogen phosphate tromethamine salt

Acetone (22.0 ml.) was added to Example 1 in its amorphous from (1.49 g). The resulting slurry was heated to 50 ⁰C and tromethamine (3.0 M solution, 1.0 equivalent) was added in small portions over a period of 30 minutes. The slurry was stirred at 50 ⁰C for 5 hours, cooled slowly to 5 ⁰C, and held with stirring for 5 hours. The stirring slurry was warmed to 20 ⁰C and held for 5 hours. The solids were isolated by vacuum filtration, washed with acetone (3 x 2.5 ml.) and dried at 50 ⁰C in a vacuum oven with a slow bleed of nitrogen to yield Example 2 as a non-solvated, crystalline solid (Form 1 C) (91.7%, 1.7 g).

¹H NMR (δ, ppm, DMSOd₆ ): 7.40 (d, 2H); 7.22 (d, 2H); 7.16 (d, 2H); 7.05 (d, 2H); 4.53 (d, 2H); 3.47 (s, 6H); 2.37 (s, 3H). Note: exchangeable protons were observed in a broad baseline peak at approximately 6.2 ppm.

¹³C solid-state NMR (δ, ppm): 173.0, 158.7, 154.9, 147.4, 145.8, 141.2, 133.2, 131.2,

127.9, 127.4, 126.4, 124.2, 122.3, 120.7, 120.1 , 117.4, 114.1 , 63.8, 58.9, 57.5, 16.9; ¹⁹F solid-state NMR (δ, ppm): -58.3; ³¹P solid-state NMR (δ, ppm): -1.1. The ¹³C, ¹⁹F and ³¹P solid-state NMR specta for Form 1 C are shown in Figure 2e, Figure 2f and Figure 2g respectively.

The X-ray powder diffraction pattern, Raman spectrum, DSC thermal data and TGA thermal data for Form 1 C are shown in Figure 2a, Figure 2b, Figure 2c, and Figure 2d respectively.

Characteristic XRPD angles and d-spacing values for Form 1 C are as follows:

Peaks marked "^*"were considered to be more characteristic of the Form 1 C than the remaining peaks.

Bands on the FT-Raman spectrum (Fig. 2b) were observed at: 604, 810, 850, 1090, 1202, 1297, 1549, 1619, 2901 , 2959, 3077 cm^"1 for Form 1 C.

An event with an onset at 166.9 ⁰C and enthalpy of 71.3 J/g was observed in the DSC for Form 1 C (Fig. 2c).

An event at 32.3 ⁰C - 87.5 ⁰C resulting in the loss of 0.07% w/w, an event at 87.5 ⁰C - 177.3 ⁰C resulting in the loss of 0.5% w/w followed by a decompositon event above 175 ⁰C was observed in the TGA of From 1 C (Fig. 2d).

¹H NMR indicated that the stoichiometry of Form 1 C was 1 :1. EXAMPLE 3

{5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl dihydrogen phosphate disodium salt

Method A.

1.4 g of {5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl dihydrogen phosphate suspended in 35 ml of water was treated dropwise with a solution of 0.228 g of NaOH in 35 ml water. The mixture was stirred at room temperature for 40 min. The solution was then filtered to remove possible solid impurities and then lyophilized to obtain 1.46 g of the desired sodium salt as a white solid (Form 1 B).

Method B.

0.2 g of {5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl dihydrogen phosphate was dissolved in 5 ml of methanol and

0.03 g of NaOH were added at 0 ⁰C. The mixture was stirred for 30 min at 0 ⁰C until the

NaOH was completely dissolved. The reaction was allowed to reach RT and stirred for additional 30 min. The solution was concentrated under vacuum to lead 0.210 g of the title compound as a white solid (Form 1 B).

¹H NMR (δ, ppm, 8O⁰C, DMSO-d₆ ): 7.37-7.27 (m, 2H); 7.18-7.05 (m, 4H); 6.99-6.90 (m,

2H); 4.48 (d, 2H); 2.24 (s, 3H). ES MS m/z: 506 [M+H]⁺.

EXAMPLE 4 {5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl dihydrogen phosphate sodium salt

Acetonitrile (2.5 ml.) was added to Example 1 in its amorphous form (107.01 mg). After addition of the solvent, the slurry was heated to 50 ⁰C and stirred at 50 ⁰C for 10 min. To the slurry, sodium hydroxide (3.0 M solution in water, 1.0 equivalent) was added in three portions over a period of 30 minutes. After the addition of the first part of the base, a clear solution was obtained with a small quantity of solids on the sides of the reactor. The slurry was left stirring at 50 ⁰C for 5 hours and cooled slowly to room temperature and left stirring at room temperature for 2 hours, cooled further to 5 ⁰C and kept stirring at 5 ⁰C for another 10 hours. The slurry was warmed to 20 ⁰C and the crystalline solids were filtered under vacuum, washed with acetonitrile and dried in a vacuum oven at 50 ⁰C with a slow bleed of nitrogen. The yield of the crystalline mono-sodium salt (Form 1 F) was 84.63 % (94.5 mgs).

¹³C solid-state NMR (δ, ppm): 173.6, 157.1 , 155.4, 147.2, 147.0, 144.1 , 142.8, 132.6, 132.0, 128.6, 127.8, 125.4, 124.3, 123.2, 122.3, 120.9, 120.0, 1 18.0, 1 14.0, 62.3, 18.5; ¹⁹F solid-state NMR (δ, ppm): -56.9; ³¹P solid-state NMR (δ, ppm): 4.8. The ¹³C, ¹⁹F and ³¹P solid-state NMR specta for Form 1A are shown in Figure 3f, Figure 3g and Figure 3h respectively.

The X-ray powder diffraction pattern, Raman spectrum, DSC thermal data, TGA thermal data and a TG-IR trace for Form 1 F are shown in Figure 3a, Figure 3b, Figure 3c, Figure 3d and Figure 3e respectively.

Characteristic XRPD angles and d-spacing values for Form 1 F are as follows:

Bands on the FT-Raman spectrum (Fig. 3b) were observed at: 598, 816, 847, 1207, 1298, 1616, 2946, 3061 cm^"1 for Form 1 F.

An event with an onset at 178.5 ⁰C and enthalpy of 53.6 J/g was observed in the DSC for Form 1 F (Fig. 3c).

An event at 35 ⁰C - 83⁰C resulting in the loss of 0.45% w/w, an event at 83 ⁰C - 200 ⁰C resulting in the loss of 3.4% w/w was observed in the TGA of From 1 F (Fig. 3d).

The TG-IR trace of Form 1 F showed the presence of water (Fig. 3e) indicating that it is a hyd rated form.

Ion chromatography indicated that Form 1 F is the mono-sodium salt. EXAMPLE 5

{5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl dihydrogen phosphate potassium salt

Hydrated Crystalline Solid - Form 1 G

Acetonitrile (2.5 ml.) was added to Example 1 in its amorphous form (103.85 mg). After addition of the solvent, the slurry was heated to 50 ⁰C and stirred at 50 ⁰C for 10 min. To the slurry, potassium hydroxide (3.0 M solution in water, 1.0 equivalent) was added in three portions over a period of 30 minutes. After complete addition of the base, the slurry was left stirring at 50 ⁰C for 5 hours and cooled slowly to room temperature and left stirring at room temperature for 2 hours, cooled to 5 ⁰C and kept stirring at 5 ⁰C for another 10 hours. The slurry was warmed to 20 ⁰C and the crystalline solids were filtered under vacuum, washed with acetonitrile and dried in a vacuum oven at 50 ⁰C with a slow bleed of nitrogen. The yield of crystalline potassium salt (Form 1 G) was 62.42 % (69.7 mgs).

The X-ray powder diffraction pattern, DSC thermal data, TGA thermal data and TG-IR trace for Form 1 G are shown in Figure 4a, Figure 4b, Figure 4c and Figure 4d respectively.

An event with an onset at 107.5 ⁰C and enthalpy of 79.7 J/g, and an event at 187.1 ⁰C and enthalpy of 48.4 J/g were observed in the DSC for Form 1 G (Fig. 4b).

An event at 35 ⁰C to 83 ⁰C resulting in the loss of 0.45% w/w, an event at 83 ⁰C to 200 ⁰C resulting in the loss of 3.4% w/w was observed in the TGA of From 1G (Fig. 4c).

TGA thermal analysis for Form 1 G shows -3.15% weight loss due to water below 135 ⁰C.

The TG-IR trace of Form 1 G showed the presence of water (Fig. 4d) indicating that it is a hydrated form.

Ion chromatography indicated that Form 1 G is the mono-potassium salt.

Non-solvated Crystalline Solid - Form 2G

The hydrated form of the potassium salt (Form 1 G) was left in a vacuum oven at 50 ⁰C overnight to produce the non-solvated, i.e. the anhydrous, potassium salt (Form 2G). The X-ray powder diffraction pattern, Raman spectrum, DSC thermal data and TGA thermal data for Form 2G are shown in Figure 5a, Figure 5b, Figure 5c and Figure 5d respectively.

Characteristic XRPD angles and d-spacing values for Form 2G are as follows:

Bands on the FT-Raman spectrum (Fig. 5b) were observed at: 596, 784, 817, 1 161 , 1206, 1297, 1615, 2940, 3079 cm^"1 for Form 2G.

An event with an onset at 186.5 ⁰C and enthalpy of 49.3 J/g was observed in the DSC for Form 2G (Fig. 5b).

An event at 35 ⁰C - 142 ⁰C resulting in the loss of 0.61% w/w followed by decomposition above 230 ⁰C resulting was observed in the TGA of From 2G (Fig. 5d).

Ion chromatography indicated that Form 2G is the mono-potassium salt.

SOLUBILITY STUDIES

Compound Solubility Determination

I. Materials

Compounds

An amount of 3 mg solid compound with LC-MS purity ≥ 95% was required. This amount was split between 3 different glass vials (1.8 ml volume each), placing 1 mg compound into each one. Solvents and buffers

Organic solvents of HPLC grade were used. Ultra pure water (MiIIi-Q grade) was used. Buffers were prepared with ultra pure water and filtered using 0.45 μ nylon filters. The compositions of each solvent employed in this assay are described below (part III).

II. Procedures.

1. Procedure for gross solubility determination: a) 100 μl of solvent was added to each vial with a digital pipette (Eppendorf Research pro). b) The mixture was subsequently subjected to vortexing for 1 min and sonicated for 5 minutes. c) Steps a) and b) were repeated until a final volume of 1 ml was reached in each vial. d) A microscope was used to examine the sample in each vial. e) The solubility of the compound in each sample was calculated as < the final concentration after all of the sample has dissolved and > the concentration before the last solvent addition. f) The solubility of the compound was calculated to be the mean value of the three vial samples.

2. Determination of equilibrium solubility (assuming chemical stability in the desired solvent is not a problem).

For each of the three vial samples prepared as described above, in which the amount of compound was totally dissolved, the following procedure was subsequently carried out: a) A small amount (approx. 0.1 mg) of additional solid compound was added to the vial to maintain an excess of the compound in the mixture in the form of undissolved solid, b) The samples were magnetically stirred for 24 hr. If required, additional solid compound (0.1 mg) was added to maintain excess of it and then the samples were stirred again. c) Then the samples were filtered (Millipore Milex filters nylon 0.2 urn) and three aliquots were taken (one from each of the three vials) and analysed by LC-MS. d) The pH of the final solution in each sample was measured with a pH-meter (WTW pH330i and a pH-electrode Sentix 41 ).

3. LC-MS assay for analytical quantification

All filtered aliquots were analysed by LC-MS. The analysis was carried out with a Luna 5μC18(2) column 4.6x150 mm, using a HP1 100 HPLC instrument interfaced with a Waters ZMD-2000 MS spectrometer. The concentration of the final sample as prepared above was calculated from that of a reference calibration curve obtained from serial dilutions of a 2 mM solution of the compound under investigation in DMSO (Aldrich cat. ref : 27685-5) stock solution. 4. Analysis of data

The analysis of all LC-MS data was performed with MassLynx 3.4 software. Statistical and graphic analysis of data was performed using Microsoft Excel. The concentration (μM) and solubility (μg/ml) for each compound was calculated using the peak areas from the sample and those from the calibration curve.

III. Compositions of solvents used in solubility determination assays.

A) FaSSIF is a solvent which simulates the Fasted State of the Intestinal Fluid.

(FaSSIF: Fasted State Simulated Intestinal Fluid). Its composition is as given in the table below.

B) FeSSIF is a solvent which simulates the Fed State of the Intestinal Fluid.

(FeSSIF: Fed State Simulated intestinal Fluid). Its composition is as given in the table below.

Reference: GaNa, Nicolaides, Horter, Lobenberg, Reppas, and Dressman - Pharmaceutical Research, Vol. 15, No. 5, 1998

C) Solubility at pH 7.4 was determined in phosphate buffered saline (PBS) (Fluka cat. ref.: 79383)

D) Solubility at pH 1.3 was determined in Simulated Gastric Fluid (SGF)

FaSSIF Preparation procedure.

1. Preparation of 1 L of pH 6.5 buffer solution

1.a. 3.947 g potassium phosphate and 16.401 g potassium chloride were dissolved in approx. 900 ml of water.

1.b. The pH was adjusted to 6.5 by slow addition of 0.1 N sodium hydroxide (Scharlau SO 044101 OC) under magnetic stirring.

1.c The mixture was diluted to a volume of 1000ml with water.

2. Preparation of 100 ml of FaSSIF

2. a. 269 mg NaTaurochol. (Aldrich T-4009) was dissolved in approx. 80 ml of pH 6.5 buffer.

2.b. 1 14 mg lecithin (Sigma P-7318) was dissolved in this NaTaurochol/buffer solution

(this was carried out with a nitrogen filled glove bag).

2. c. The resulting mixture was diluted to a volume of 100 ml with further pH 6.5 buffer

2.d. The final solution was covered with a layer of nitrogen or alternative inert gas. The bottle was sealed with parafilm and stored at 4⁰C.

FeSSIF Preparation procedure.

1. Prepare 1 L of pH 5 buffer solution

1.a. 15.2 g potassium chloride and 8.25 ml glacial acetic acid were dissolved in approx. 900 ml of water.

1.b. The pH was adjusted to 5 by slow addition of NaOH 0.1 N (Scharlau SO

044101 OC) under magnetic stirring.

1.c The mixture was diluted to a volume of 1000 ml with water.

2. Preparation of 100 mL of FeSSIF

2. a. 806.5 mg NaTaurochol (Aldrich T-4009) was dissolved in 80 ml of pH 5 buffer. 2.b. 288 mg lecithin (Sigma P-7318) was dissolved in this NaTaurochol/buffer solution (carried out with a nitrogen filled glove bag). 2. c. The resulting solution was diluted to a volume of 100 ml with pH 5 buffer. 2.d. The final solution was covered with a layer of nitrogen or alternative inert gas. The bottle was sealed with parafilm and stored at 4⁰C.

Simulated Gastric Fluid (SGF) Preparation procedure

Dissolve 2.0 g of sodium chloride and 7 ml. of concentrated hydrochloric acid into approximately 500 ml. of purified water. Check the pH and adjust if necessary to pH 1.3 with a few drops of concentrated HCI. Add 5g of sodium lauryl sulfate and stir to complete dissolution. Make up to 1 Litre volume and record pH. Some frothing is apparent when preparing these solutions.

Results of solubility determination assays

The solubility of Example 1 was tested in each of four aqueous media (PBS, FeSSIF, FaSSIF and SGF) using the material prepared in Example 1 , Method A, Batch (ii) and was compared against 3-chloro-6-(hydroxymethyl)-2-methyl-5-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-4(1 H)-pyridinone. The data are shown in the Solubility Table below.

Solubility Table

Key to Table:

S = solubility in μg/ml

S<1

KS<5

5<S<10

10<S<50

50<S<500 ^*****

500<S<1000 ^******

1000<S ^******* Solubility Profiles

A pH-solubility profile for Example 1 was generated using the crystalline free acid (Form 1A) and using the amorphous free acid. A profile was also generated for comparative compound 3-chloro-6-(hydroxymethyl)-2-methyl-5-[4-({4-[(trifluoro methyl)oxy]phenyl}oxy)phenyl]-4(1 H)-pyridinone using the crystalline free acid. An overlay of the solubility profiles of Form 1A and the comparative compound is shown in Figure 6. The crystalline prodrug (Example 1 - Form 1A) yielded a dramatic Gl-relevant pH- solubility increase compared to the comparative compound.

Solubility Determination Method

Samples were prepared based on predicted solubilities (based on related analogs and calculated pK_a's) since the phase separation (filtration) technique is volume-dependent based on measured solubility. The solid was equilibrated with aqueous buffers using vials and stir bars appropriate for the target volume. If the solid fully dissolved, or conversely if measured solubility fell into a lower solubility range that indicated that a different filtration technique was required, solid and buffer amounts were modified accordingly.

Calculated pKa's

Example 1 Comparative Compound

Solubility Determination

Samples were equilibrated at ambient temperature (typically 22 - 23 ⁰C). Aliquots were filtered and assayed; typically at 3 timepoints unless samples were adequately equilibrated at an earlier timepoint. The filtration method used depended on the expected solubility, with the filter diameter (surface area) and filtration/discard volumes designed to eliminate filter sorption errors while minimizing the total volume needed (to conserve sample). In all cases, Millipore PVDF 0.45-μm filter membranes are used. For high solubilities (typically >= 500 μg/mL) a microcentrifuge tube filter (Ultrafree-MC-HV

UFC30HVNB) is used with a 300-uL filtration volume (no pre-rinse). For lower solubilities, the entire sample vial was centrifuged to sediment most excess solid, then a 13-mm syringe filter (Millex-HV SLHVT13NL) was used with a pre-rinse (first 1 mL discarded, final 1 mL into HPLC vial for assay, the intermediate back into the sample). For low to moderate solubilities (typically 0.1 to 500 μg/mL) a 10-mL aliquot was filtered. For very low solubilities (typically <= 0.1 μg/mL), a 40-mL aliquot was filtered. Techniques were adjusted as necessary based on measured vs. expected solubility.

Filtrates were assayed using a generic gradient HPLC method (typically an Agilent HP1100 with Phenomenex Luna C18(2) column and acetonitrile/water/TFA mobile phases), with dilution factors and injection volumes chosen to yield reasonable peak areas.

Solubility Profile Data

Data for Example 1 (amorphous)

Solubility fa/fb-equiv spl PH (mg/mL)

Example 1 (amorph) fa-b 0.3 M HCI day1 0.64 0.195 Example 1 (amorph) fa-b 0.1 M HCI day6 1.16 0.119 Example 1 (amorph) fa-b SGF pH 1.6 day5 1.66 0.160 Example 1 (amorph) fa-b pH 2 B-R day6 2.02 0.301 Example 1 (amorph) fa-b pH 2.5 B-R day5 2.47 0.896 Example 1 (amorph) fa-b pH 3 B-R day5 2.83 1.70 Example 1 (amorph) fa-b pH 3.5 B-R day4 2.88 2.85

Solubilities above pH 3 were not generated for Example 1 (amorphous).

Data for Example 1 (Form 1A)

Solubility fa/fb-equiv spl PH (mg/mL)

Example 1 (Form 1A) fa-b 0.3 M HCI day5 0.58 0.0617 Example 1 (Form 1A) fa-b 0.1 M HCI day3 1.05 0.0276 Example 1 (Form 1A) fa-b SGF pH 1.6 day3 1.59 0.0530 Example 1 (Form 1A) fa-b pH 3 B-R day5 3.01 0.398 Example 1 (Form 1A) fa-b pH 4.5 B-R day3 3.79 6.06 Example 1 (Form 1A) fa-b 0.1 M NaOH 2hr 4.81 42.4 Solubilities above pH 5 were not generated for Example 1 (Form 1A).

Data for comparative compound 3-chloro-6-(hydroxymethyl)-2-methyl-5-[4-({4-[(trifluoro methyl)oxy]phenyl}oxy)phenyl]-4(1 H)-pyridinone

Solubility fa/fb-equiv spl pH (mg/mL)

Comparative fa-b 0.1 M HCI dayθ 1.14 0.001 Θ9 Comparative fa-b pH 4 B-R dayθ 4.13 0.0004Θ3 Comparative fa-b pH 6.5 B-R dayθ Θ.5Θ 0.000499 Comparative fa-b pH 1 1 piperidine day13 10.94 0.00Θ91 Comparative fa-b pH 12 NaOH-KCI day13 12.01 0.0581 Comparative fa-b 0.1 M NaOH dayθ 12.8Θ 0.5Θ3

The data for Example 1 (Form 1A) and the comparative compound was plotted and fit to following equations based on the ionization scheme to provide the solubility curves shown in Figure 6.

Claims

1. A compound of Formula I:

or a salt thereof.

2. The compound according to claim 1 , which is in the form of the free acid.

3. A salt of the compound according to claim 1 , which is a tromethamine salt, a sodium salt or a potassium salt.

4. A crystalline solid of the compound or salt thereof according to any of claims 1 to 3.

A compound in the form of the free acid according to claim 4, which is characterised by one or more of: a. an X-ray powder diffraction (XRPD) spectra comprising 2 theta angle peaks at 5.7, 5.9, 9.7, 1 1.4, 11.9, 12.9, 15.1 , 16.7, 17.2, 21.4, 22.4 degrees to

±0.2°; b. bands on the FT-Raman spectrum at: 593, 818, 854, 1 166, 1215, 1612,

2946, 3076 cm -^"1' to ±4 cm ,-^"1'.; c. ¹⁹F solid-state NMR peak at (δ, ppm from CFCI₃): -54.5 to ±0.2 ppm; d. ³¹P solid-state NMR peaks at (δ, ppm from 85% H₃PO₄): -0.3 and -1.4 to

±0.2 ppm; and e. at least 16 ¹³C solid-state NMR peaks selected from peaks at (δ, ppm from tetramethylsilane): 156.5, 155.1 , 153.3, 152.8, 149.9, 148.1 , 146.1 , 145.6,

143.5, 142.5, 135.9, 133.2, 132.5, 131.2, 127.0, 124.

5, 122.3, 119.3, 117.6,

116.9, 115.1 and 114.0 to ±0.2 ppm.

6. The compound according to claim 5, characterised by at least two of a to e.

7. The compound according to claim 5, characterised by all five of a to e.

8. A tromethamine salt according to claim 4, which is characterised by one or more of: a. an X-ray powder diffraction (XRPD) spectra comprising 2 theta angle peaks at 6.7, 15.3, 17.2, 18.1 , 20.2, 21.0, 21.5, 24.8, 27.1 degrees to ±0.2°; b. bands on the FT-Raman spectrum at: 593, 818, 854, 1166, 1215, 1612, 2946, 3076 cm^"1 to ±4 cm^"1; c. ¹⁹F solid-state NMR peak at (δ, ppm from CFCI₃): -58.3 to ±0.2 ppm; d. ³¹P solid-state NMR peaks at (δ, ppm from 85% H₃PO₄): -1.1 to ±0.2 ppm; and e. at least 12 ¹³C solid-state NMR peaks selected from peaks at (δ, ppm from tetrmethylsilane): 158.7, 154.9, 147.4, 145.8, 141.2, 133.2, 131.2, 127.9, 127.4, 126.4, 124.2, 122.3, 120.7, 120.1 , 1 17.4 and 114.1 to ±0.2 ppm.

9. The tromethamine salt according to claim 8, characterised by at least two of a to e.

10. The tromethamine salt according to claim 8, characterised by all five of a to e.

1 1. A sodium salt of the compound according to claim 4, which is a hydrated, mono- sodium salt which is characterised by one or more of: a. an X-ray powder diffraction (XRPD) spectra comprising 2 theta angle peaks at 11.7, 15.7, 16.3, 18.7, 19.9, 22.5, 24.4, 25.1 , 27.9 to ±0.2°; b. bands on the FT-Raman spectrum at: 598, 816, 847, 1207, 1298, 1616, 2946, 3061 cm^"1 to ±4 cm^"1; a. ¹⁹F solid-state NMR peak at (δ, ppm from CFCI₃): -58.3 to ±0.2 ppm; b. ³¹P solid-state NMR peaks at (δ, ppm from 85% H₃PO₄): -1.1 to ±0.2 ppm; and c. at least 14 ¹³C solid-state NMR peaks selected from peaks at (δ, ppm from tetrmethylsilane): 157.1 , 155.4, 147.2, 147.0, 144.1 , 142.8, 132.6, 132.0, 128.6, 127.8, 125.4, 124.3, 123.2, 122.3, 120.9, 120.0, 1 18.0 and 114.0 to ±0.4 ppm.

12. The sodium salt according to claim 1 1 , characterised by at least two of a to e.

13. The sodium salt according to claim 1 1 , characterised by all five of a to e.

14. A hydrated, mono-potassium salt of the compound of claim 4 which is characterized by an X-ray powder diffraction (XRPD) pattern substantially as shown in Figure 4a, wherein the XRPD pattern is expressed in terms of 2 theta angles and obtained with a diffractometer equipped with a diffracted beam monochromator using copper Ka radiation.

15. A hydrated, mono-potassium salt of the compound of claim 4 which is characterized by at least two of: a. an onset of melting in the range 105.5-109.5 ⁰C; b. an enthalpy of melting in the range of 78-81 J/g; c. a DSC thermogram substantially in accordance with Figure 4b; and d. a TGA thermogram substantially in accordance with Figure 4c.

16. An anhydrous, mono-potassium salt of the compound of claim 4, which is characterised by: a. an X-ray powder diffraction (XRPD) spectra comprising 2 theta angle peaks at 5.7, 5.8, 11.3, 11.6, 16.2, 16.6, 18.9, 19.3, 20.9, 22.5 to ±0.2; and/or b. bands on the FT-Raman spectrum at: 596, 784, 817, 1161 , 1206, 1297, 1615, 2940, 3079 cm^"1 to to ±4 cm^"1.

17. A compound or a salt thereof according to any preceding claim, for use in medical therapy.

18. Use of a compound of Formula I or a salt thereof according to any one of claims 1 to 16, in the manufacture of a medicament for the treatment of malaria.

19. A method for the treatment of malaria comprising administering to a patient suffering therefrom an effective amount of a compound or salt thereof of any of claims 1 to 16.

20. The use according to claim 18 or the method according to claim 19 wherein malaria is caused by infection with Plasmodium falciparum.

21. A pharmaceutical composition comprising a compound or a salt thereof according to any one of claims 1 to 16, and one or more pharmaceutically acceptable carriers and/or excipients.

22. The pharmaceutical composition according to claim 21 for parenteral administration.

23. The pharmaceutical composition according to claim 21 or claim 22 in the form of a solid for reconstitution into a liquid dosage form.

24. A pharmaceutical composition comprising a compound or a salt thereof according to any one of claims 1 to 3, in the form of a liquid dosage for injection or infusion, in which the compound or salt is present as a solution in one or more liquid carriers.

25. The pharmaceutical composition according to any one of claims 21 to 24 comprising a combination of a compound or a salt thereof according to any one of claims 1 to 16, and a further active thereapeutic agent.

26. {5-chloro-6-methyl-4-oxo-3-[4-({4-[(trifluoromethyl)oxy]phenyl} oxy)phenyl]-1 ,4- dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate or a salt thereof.

27. A method of making the compound according to claim 1 or a salt thereof, comprising the step of deprotecting {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl} oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate and, optionally, contacting the compound of claim 1 with a base to form a salt.

28. A method of claim 27 further comprising the step of combining 3-chloro-6- (hydroxymethyl)-2-methyl-5-[4-({4-[(trifluoromethyl) oxy]phenyl}oxy)phenyl]-4(1 H)- pyridinone with tetrabenzyl pyrophosphate under conditions in which the 6- hydroxymethyl group of 3-chloro-6-(hydroxymethyl)-2-methyl-5-[4-({4- [(trifluoromethyl) oxy]phenyl}oxy)phenyl]-4(1 H)-pyridinone is selectively phosphorylated to form {5-chloro-6-methyl-4-oxo-3-[4-({4- [(trifluoromethyl)oxy]phenyl}oxy)phenyl]-1 ,4-dihydro-2-pyridinyl}methyl bis(phenylmethyl) phosphate thereof.

29. The method according to claim 28, wherein the 6-hydroxymethyl group is deprotonated in the presence of lithium hydride and a hindered alcohol.