EP1546132A1

EP1546132A1 - Pyrazole derivatives as reverse transcriptase inhibitors

Info

Publication number: EP1546132A1
Application number: EP03798326A
Authority: EP
Inventors: Oscar Pfizer Global Research & Development BARBA; L. H. Pfizer Global Research & Development JONES
Original assignee: Barba Oscar; Pfizer Ltd
Current assignee: Barba Oscar; Pfizer Ltd
Priority date: 2002-09-26
Filing date: 2003-09-15
Publication date: 2005-06-29
Also published as: CA2497333A1; JP2006504803A; AU2003260908A1; MXPA05003195A; WO2004029042A1; BR0314709A

Abstract

This invention relates to pyrazole derivatives of formula (I) or pharmaceutically acceptable salts, solvates or derivative thereof, wherein R' to R4 are defined in the description, and to processes for the preparation thereof, intermediates used in their preparation of, compositions containing them and the uses of such derivatives. The compounds of the present invention bind to the enzyme reverse transcriptase and are modulators, especially inhibitors thereof. As such the compounds of the present invention are useful in the treatment of a variety of disorders including those in which the inhibition of reverse transcriptase is implicated. Disorders of interest include those caused by Human Immunodificiency Virus (HIV) and genetically related retroviruses, such as Acquired Immune Deficiency Syndrome (AIDS).

Description

Pyrazole Derivatives

This invention relates to pyrazole derivatives, to their use in medicine, to compositions containing them, to processes for their preparation and to intermediates used in such processes.

Reverse transcriptase is implicated in the infectious lifecycle of Human Immunodeficiency Virus (HIV). Compounds which interfere with the function of this enzyme have shown utility in the treatment of conditions caused by HIV and genetically related retroviruses, such as Acquired Immune Deficiency Syndrome (AIDS). There is a constant need to provide new and better modulators, especially inhibitors, of HIV reverse transcriptase, since the virus is able to mutate, becoming resistant to the effects of known modulators.

Antiviral activity is ascribed to a class of N(hydroxyethyl)pyrazole derivatives in US patent number 3,303,200. A number of pyrazoles are disclosed as reverse transcriptase inhibitors, including: a class of N-phenylpyrazoles (J. Med. Chem., 2000, 43, 1034); a class of C and S linked aryl pyrazoles (WO02/04424); and a class of O and S linked aryl pyrazoles, the O and S aryl link being adjacent to the nitrogen atom (WO02/30907).

According to the present invention there is provided a compound of formula (I)

or a pharmaceutically acceptable salt, solvate or derivative thereof, wherein:

R¹ is a five or six-membered, aromatic heterocyclic group containing (i) from 1 to 4 nitrogen heteroatom(s) or (ii) 1 or 2 nitrogen heteroatom(s) and 1 oxygen or 1 sulphur heteroatom or (iii) 1 or 2 oxygen or sulphur heteroatom(s), said heterocyclic group being optionally substituted by halo, oxo, -CN, -COR⁵, -CONR⁵R⁵, -S0₂NR⁵R⁵, -NR⁵SO₂R⁵, -OR⁵, OR¹¹, -NR⁵R⁵,

-(C C₆ alkylene)-NR⁵R⁵, R⁷ or R¹¹; R² is H, Cι-C₆ alkyl, C₃-C₆ alkenyl, C₃-C₆ alkynyl, C₃-C cycloalkyl, C_3-C₇ cycloalkenyl, phenyl, benzyl, R⁸ or R⁹, said CrC₆ alkyl, C₃-C₇ cycloalkyl, phenyl and benzyl being optionally substituted by halo, -OR⁵, -OR¹⁰, -CN, -C0₂R⁷, -OCONR⁵R⁵, -CONR⁵R⁵, -C(=NR⁵)NR⁵OR⁵, -CONR⁵NR⁵R⁵, -NR⁶R⁶, -NR⁵R¹⁰, -NR⁵COR⁵, -NR⁵COR⁸, -NR⁵COR¹⁰, -NR⁵C0₂R⁵, -NR⁵CONR⁵R⁵, -SO₂NR⁵R⁵, -NR⁵SO₂R⁵, -NR⁵SO₂NR⁵R⁵, R⁸ or R⁹;

R³ is H, CrC₆ alkyl, C₃-C₇ cycloalkyl, phenyl, benzyl, halo, -CN, -OR⁷, -CO₂R⁵, -CONR⁵R⁵, R⁸ or R⁹, said C C₆ alkyl, C₃-C₇ cycloalkyl, phenyl and benzyl being optionally substituted by halo, -CN, -OR⁵, -C0₂R⁵, -CONR⁵R⁵, -OCONR⁵R⁵, -NR⁵CO₂R⁵, -NR⁶R⁶, -NR⁵COR⁵, -SO₂NR⁵R⁵, -NR⁵CONR⁵R⁵, -NR⁵S0₂R⁵, R⁸ or R⁹;

R⁴ is phenyl, naphthyl or pyridyl, each being optionally substituted by R⁸, halo, -CN, C C₆ alkyl, C C₆ haloalkyl, C₃-C₇ cycloalkyl, C C₆ alkoxy, -CONR⁵R⁵, OR¹¹, SθχR⁶, 0-(Cι-C₆ alkylene)-CONR⁵R⁵, 0-(C C₆ alkylene)-NR⁵R⁵, or 0.(Cι-C_β alkylene)-OR⁶;

each R⁵ is independently either H, C C₆ alkyl or C₃-C cycloalkyl or, when two R⁵ groups are attached to the same nitrogen atom, those two groups taken together with the nitrogen atom to which they are attached represent azetidinyl, pyrrolidinyl, piperidinyl, homopiperidinyl, piperazinyl, homopiperazinyl or morpholinyl, said azetidinyl, pyrrolidinyl, piperidinyl, homopiperidinyl, piperazinyl, homopiperazinyl and morpholinyl being optionally substituted by CrC₆ alkyl or C₃-C₇ cycloalkyl;

each R⁶ is independently either H, C C₆ alkyl or C₃-C cycloalkyl;

R⁷ is C C₆ alkyl or C₃-C cycloalkyl;

R⁸ is a five or six-membered, aromatic heterocyclic group containing (i) from 1 to 4 nitrogen heteroatom(s) or (ii) 1 or 2 nitrogen heteroatom(s) and 1 oxygen or 1 sulphur heteroatom or (iii) 1 or 2 oxygen or sulphur heteroatom(s), said heterocyclic group being optionally substituted by halo, oxo, -CN, -COR⁵, -CONR⁵R⁵, -S0₂NR⁵R⁵, -NR⁵SO₂R⁵, -OR⁵, -NR⁵R⁵, -(C C₆ alkylene)-NR⁵R⁵, C C₆ alkyl, fluoro(CrC₆)alkyl or C₃-C cycloalkyl;

R⁹ is a four to seven-membered, saturated or partially unsaturated heterocyclic group containing (i) 1 or 2 nitrogen heteroatom(s) or (ii) 1 nitrogen heteroatom and 1 oxygen or 1 sulphur heteroatom or (iii) 1 oxygen or sulphur heteroatom, said heterocyclic group being optionally substituted by oxo, C C-6 alkyl, C-₃-C₇ cycloalkyl, -S0₂R⁵, -CONR⁵R⁵, -COOR⁵, -CO-(C C₆ alkylene)-OR⁵ or -COR⁵ and optionally substituted on a carbon atom which is not adjacent to a heteroatom by halo, -OR⁵, -NR⁵R⁵, -NR⁵COR⁵, -NR⁵COOR⁵, -NR⁵CONR⁵R⁵, -NR⁵SO₂R⁵ or -CN;

R¹⁰ is Cι-C₆ alkyl substituted by R⁸, R⁹, -OR⁵, -CONR⁵R⁵, -NR⁵COR⁵ or -NR⁵R⁵;

R¹¹ is phenyl optionally substituted by halo, -CN, -COR⁵, -CONR⁵R⁵, -S0₂NR⁵R⁵, -NR⁵SO₂R⁵, -OR⁵, -NR⁵R⁵, -(C C₆ alkylene)-NR⁵R⁵, CrC₆ alkyl, halo(C C₆)alkyl or C₃-C cycloalkyl; and

x is 0, 1 or 2.

In the above definitions, halo means fluoro, chloro, bromo or iodo. Unless otherwise stated, alkyl, alkenyl, alkynyl, alkylene and alkoxy groups containing the requisite number of carbon atoms can be unbranched or branched chain. Examples of alkyl include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec- butyl and t-butyl. Examples of alkenyl include ethenyl, propen-1-yl, propen-2-yl, propen-3-yl, 1 -buten-1 -yl, 1-buten-2-yl, 1-buten-3-yl, 1-buten-4-yl, 2-buten-1 -yl, 2- buten-2-yl, 2-methylpropen-1 -yl or 2-methylpropen-3-yl. Examples of alkynyl include ethynyl, propyn-1-yl, propyn-3-yl, 1-butyn-1-yl, 1-butyn-3-yl, 1-butyn-4-yl, 2-butyn-1-yl. Examples of alkylene include methylene, 1 ,1-ethylene, 1 ,2- ethylene, 1 ,1-propylene, 1 ,2-propylene, 2,2-propylene and 1 ,3-propylene. Examples of alkoxy include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i- butoxy, sec-butoxy and t-butoxy. Examples of cycloalkyl include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. Where R¹ and R² are taken together, they form, along with the nitrogen atom and the carbon atom of the pyrazole ring to which they are attached, a 5- or 6-membered ring. Where a heterocyclic group R⁸ or R⁹ is attached to an oxygen, sulphur or nitrogen heteroatom the heterocyclic group R⁸ or R⁹ must be linked through a ring carbon atom. Further, where a heterocyclic group R⁹ is attached to an oxygen, sulphur or nitrogen heteroatom the heterocyclic group R⁹ must be linked through a ring carbon atom that is not adjacent to a ring heteratom.

The pharmaceutically acceptable salts of the compounds of formula (I) include the acid addition and the base salts thereof. Suitable acid addition salts are formed from acids which form non-toxic salts and examples are the hydrochloride, hydrobromide, hydroiodide, chloride, bromide, iodide, sulphate, bisulphate, nitrate, phosphate, hydrogen phosphate, acetate, fumarate, pamoate, aspartate, besylate, carbonate, bicarbonate/, camsylate, D and L-lactate, D and L-tartrate, esylate, mesylate, malonate, orotate, gluceptate, methylsulphate, stearate, glucuronate, 2-napsylate, tosylate, hibenzate, nicotinate, isethionate, malate, maleate, citrate, gluconate, succinate, saccharate, benzoate, esylate, and pamoate salts.

Suitable base salts are formed from bases which form non-toxic salts and examples are the sodium, potassium, aluminium, calcium, magnesium, zinc, choline, diolamine, olamine, arginine, glycine, tromethamine, benzathine, lysine, meglumine and diethylamine salts.

For reviews on suitable salts see Berge et al, J. Pharm. Sci., 66, 1-19, 1977 and Bighley et al, Encyclopedia of Pharmaceutical Technology, Marcel Dekker Inc, New York, 1996, Vol 13, pp453-497

The pharmaceutically acceptable solvates of the compounds of formula (I) include the hydrates thereof.

The compound of formula (I) may be modified to provide pharmaceutically acceptable derivatives thereof at any of the functional groups in the compound. Examples of such derivatives are described in: Drugs of Today, Volume 19, Number 9, 1983, pp 499 - 538; Topics in Chemistry, Chapter 31 , pp 306 - 316; and in "Design of Prodrugs" by H. Bundgaard, Elsevier, 1985, Chapter 1 (the disclosures in which documents are incorporated herein by reference) and include: esters, carbonate esters, hemi-esters, phosphate esters, nitro esters, sulfate esters, sulfoxides, amides, sulphonamides, carbamates, azo-compounds, phosphamides, glycosides, ethers, acetals and ketals.

The invention encompasses all isomers of the compound of formula (I) and pharmaceutically acceptable salts, solvates or derivatives thereof, including all geometric, tautomeric and optical forms, and mixtures thereof (e.g. racemic mixtures).

Separation of diastereoisomers may be achieved by conventional techniques, e.g. by fractional crystallisation, chromatography or high performance liquid chromatography (HPLC) of a stereoisomeric mixture of compounds. An individual enantiomer of a compound may also be prepared from a corresponding optically pure intermediate or by resolution, such as by HPLC of the corresponding racemate using a suitable chiral support, or by fractional crystallisation of the diastereoisomeric salts formed by reaction of the corresponding racemate with a suitable optically active acid or base, as appropriate.

The compound of formula (I) and pharmaceutically acceptable salts, solvates or derivatives thereof may have the ability to crystallize in more than one form, a characteristic known as polymorphism, and all such polymorphic forms ("polymorphs") are encompassed within the scope of the invention. Polymorphism generally can occur as a response to changes in temperature or pressure or both, and can also result from variations in the crystallization process. Polymorphs can be distinguished by various physical characteristics, and typically the x-ray diffraction patterns, solubility behaviour, and melting point of the compound are used to distinguish polymorphs.

Compounds of formula (I), pharmaceutically acceptable salts, solvates and derivatives thereof, isomers thereof, and polymorphs thereof, are hereinafter referred to as the compounds of the invention.

Preferred compounds of the invention are the compounds of formula (I) and pharmaceutically acceptable salts and solvates thereof.

Preferably, R¹ is a five or six-membered, aromatic heterocyclic group containing (i) from 1 to 2 nitrogen heteroatom(s) or (ii) 1 nitrogen heteroatom and 1 oxygen or 1 sulphur heteroatom, said heterocyclic group being optionally substituted by halo, oxo, -CN, -OR⁵, -OR¹¹, -NR⁵R⁵, -(Cι-C₆ alkylene)-NR⁵R⁵, R⁷ or R¹¹. Preferably, R¹ is a five or six-membered, aromatic heterocyclic group containing (i) from 1 to 2 nitrogen heteroatom(s) or (ii) 1 nitrogen heteroatom and 1 sulphur heteroatom, said heterocyclic group being optionally substituted by -OR¹¹, -NR⁵R⁵, R⁷ or R¹¹.

Preferably, R¹ is a five or six-membered, aromatic heterocyclic group containing (i) from 1 to 2 nitrogen heteroatom(s) or (ii) 1 nitrogen heteroatom and 1 sulphur heteroatom, said heterocyclic group being optionally substituted by CrCβ alkyl, phenyl, phenoxy, C C₆ alkoxyphenoxy or -NR⁵R⁵.

Preferably, R¹ is pyridinyl, pyrimidinyl, pyrazinyl or thiazolyl, each being optionally substituted by C C₂ alkyl, phenyl, CrC₂ alkoxyphenoxy, -N(CH₃)₂, -N(CH₂CH₃)₂ or N(CH₃)( CH₂CH₃). Preferably, R² is H, CrC₆ alkyl, C₃-C₆ alkenyl, phenyl, benzyl or R⁹, said phenyl, benzyl or Cι-C₆ alkyl being optionally substituted by halo, -OR⁵, -OR¹⁰, -CN, -C0₂R⁷, -OCONR⁵R⁵, -CONR⁵R⁵, -C(=NR⁵)NR⁵OR⁵, -CONR⁵NR⁵R⁵, -NR⁶R⁶, -NR⁵R¹⁰, -NR⁵COR⁵, -NR⁵COR⁸, -NR⁵COR¹⁰, -NR⁵C0₂R⁵, -NR⁵CONR⁵R⁵, -S0₂NR⁵R⁵, -NR⁵S0₂R⁵, R⁸ or R⁹.

Preferably, R² is Cι-C₆ alkyl, phenyl or benzyl, said C C₆ alkyl being optionally substituted by halo, -OR⁵, -OR¹⁰ or -CN.

Preferably, R² is C₁-C₃ alkyl or benzyl, said C C₃ alkyl being optionally substituted by -CN.

Preferably, R³ is H, C C₆ alkyl or C₃-C₇ cycloalkyl, said C C₆ alkyl being optionally substituted by halo, -CN, -OR⁵, -C0₂R⁵, -CONR⁵R⁵, -OCONR⁵R⁵, -NR⁵CO₂R⁵, -NR⁶R⁶, -NR⁵COR⁵, -SO₂NR⁵R⁵, -NR⁵CONR⁵R⁵, -NR⁵S0₂R⁵, R⁸ or R⁹.

Preferably, R³ is H or C C₆ alkyl. Preferably, R³ is H or C C₄ alkyl. Preferably, R³ is methyl or ethyl.

Preferably, R⁴ is phenyl optionally substituted by R⁸, halo, -CN, CrC₆ alkyl, Cι-C₆ haloalkyl, C₃-C cycloalkyl or d-Cβ alkoxy.

Preferably, R⁴ is phenyl substituted by R⁸, halo, -CN, CrC₆ alkyl, or C C₆ alkoxy. Preferably, R⁴ is phenyl substituted by -CN. Preferably, R⁴ is 3,5-dicyanophenyl.

Preferably, R⁸ is pyrrolyl, imidazolyl, pyrazolyl, 1 ,2,3-triazolyl, 1 ,2,4-triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, 1 ,2,4-oxadiazolyl, 1 ,3,4-oxadiazolyl, furanyl, thienyl, pyridinyl, pyridazinyl, pyrimidinyl or pyrazinyl, each being optionally substituted by halo, -CN, -COR⁵, -CONR⁵R⁵, -SO₂NR⁵R⁵, -NR⁵SO₂R⁵, -OR⁵, -NR⁵R⁵, -(C_rC₆ alkylene)-NR⁵R⁵, C C₆ alkyl, fluoro(Cι-C₆)alkyl or C₃-C₇ cycloalkyl.

Preferably, R⁸ is imidazolyl, pyrazolyl, 1 ,2,4-triazolyl, 1 ,2,4-oxadiazolyl, 1 ,3,4-oxadiazolyl, pyridinyl, pyrazinyl or pyrimidinyl, each being optionally substituted by halo, -CN, -COR⁵, -CONR⁵R⁵, -S0₂NR⁵R⁵, -NR⁵S0₂R⁵, -OR⁵, -NR⁵R⁵, -(Cι-C₆ alkylene)-NR⁵R⁵, C C₆ alkyl, fluoro(C C₆)alkyl or C₃-O₇ cycloalkyl.

Preferably, R⁸ is imidazolyl, pyrazolyl, 1 ,2,4-triazolyl, 1 ,2,4-oxadiazolyl, 1 ,3,4-oxadiazolyl, pyridinyl, pyrazinyl or pyrimidinyl, each being optionally substituted by -OR⁵, -NR⁵R⁵ or C C₆ alkyl. Preferably, R⁸ is imidazolyl, pyrazolyl, 1 ,2,4-triazolyl, 1 ,2,4-oxadiazolyl, 1 ,3,4-oxadiazolyl, pyridinyl, pyrazinyl or pyrimidinyl, each being optionally substituted by -OH, -NH₂ or methyl.

Preferably, R⁹ is azetidinyl, tetrahydropyrrolyl, piperidinyl, azepinyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, oxepinyl, morpholinyl, piperazinyl or diazepinyl, each being optionally substituted by oxo, d-Cβ alkyl, C-₃-C₇ cycloalkyl, -SO₂R⁵, -CONR⁵R⁵, -COOR⁵, -CO-(d-C₆ alkylene)-OR⁵ or -COR⁵ and optionally substituted on a carbon atom which is not adjacent to a heteroatom by halo, -OR⁵, -NR⁵R⁵, -NR⁵COR⁵, -NR⁵COOR⁵, -NR⁵CONR⁵R⁵, -NR⁵S0₂R⁵ or -CN.

Preferably, R⁹ is azetidinyl, piperidinyl, tetrahydrofuranyl, piperazinyl or morpholinyl, each being optionally substituted by oxo, Cι-C₆ alkyl, C₃-C₇ cycloalkyl, -S0₂R⁵, -CONR⁵R⁵, -COOR⁵, -CO-(C C₆ alkylene)-OR⁵ or -COR⁵ and optionally substituted on a carbon atom which is not adjacent to a heteroatom by halo, -OR⁵, -NR⁵R⁵, -NR⁵COR⁵, -NR⁵COOR⁵, -NR⁵CONR⁵R⁵, -NR⁵S0₂R⁵ or -CN.

Preferably, R⁹ is azetidinyl, piperidinyl, tetrahydrofuranyl, piperazinyl or morpholinyl, each being optionally substituted by d-C₆ alkyl, -S0₂R⁵, -CONR⁵R⁵, -COOR⁵, -CO-(Cι-C₆ alkylene)-OR⁵ or -COR⁵ and optionally substituted on a carbon atom which is not adjacent to a heteroatom by -OR⁵ or -NR⁵COR⁵.

Preferably, R⁹ is azetidinyl, piperidinyl, tetrahydrofuranyl, piperazinyl or morphoninyl, each being optionally substituted by -CH₃, -SO₂CH₃, -CONH₂, -COOCH₃, -COCH₂OCH₃ or -COCH₃ and optionally substituted on a carbon atom which is not adjacent to a heteroatom by -OCH₃ or -NHCOCH₃.

Preferably, R¹⁰ is d-C₄ alkyl substituted by R⁸, R⁹, -OR⁵, -CONR⁵R⁵, -NR⁵COR⁵ or -NR⁵R⁵.

Preferably, R¹⁰ is C C₄ alkyl substituted by R⁹, -OR⁵, -NR⁵COR⁵ or -NR⁵R⁵. Preferably, R¹⁰ is C C₂ alkyl substituted by tetrahydrofuranyl, -OCH₃, -NHCOCH₃ or -NH₂.

Preferably, R¹¹ is phenyl substituted by halo, -CN, -COR⁵, -CONR⁵R⁵, -SO₂NR⁵R⁵, -NR⁵SO₂R⁵, -OR⁵, -NR⁵R⁵, -(C C₆ alkylene)-NR⁵R⁵, C C₆ alkyl, halo(CrC₆)alkyl or C₃-C₇ cycloalkyl. Preferably, R¹¹ is phenyl substituted by halo, -CN, -CONR⁵R⁵, -S0₂NR⁵R⁵ or -OR⁵.

Preferably, R¹¹ is phenyl substituted by -OR⁵. Preferably, R¹¹ is phenyl substituted by CrC₂ alkoxy. Preferred groups of compounds according to the invention include all combinations of the preferred definitions for individual substituents given above.

Preferred compounds of the invention are: 5-[3-Ethyl-1 -methyl-5-(pyridin-2-yloxy)-1 H-pyrazol-4-yloxy]-isophthalonitrile; the compound of Example 6; and its pharmaceutically acceptable salts, solvates or derivatives.

The compounds of the invention may have advantages over those of the prior art with regard to a number of useful properties or combination thereof, such as potency, duration of action, pharmacokinetics, spectrum of activity, side effect profile, solubility, chemical stability, and so on.

The compounds of the invention may be prepared by any method known in the art for the preparation of compounds of analogous structure. The compounds of the invention can be prepared by the procedures described in the methods below, or by the specific methods described in the Examples, or by similar methods to either. The invention also encompasses any one or more of these processes for preparing the compounds of the invention, in addition to any novel intermediates used therein.

In the following methods, R¹, R², R³ and R⁴ are as previously defined for a compound of formula (I), unless otherwise stated, and R^a is an alkyl group, such as a lower alkyl group (e.g. methyl).

Compounds of formula (I) may be prepared according to Scheme 1 ,

According to Scheme 1 , compounds of formula (I) may be prepared by the reaction of a compound of formula (V) with an alcohol of formula (IV) under conventional conditions. Conveniently, the reaction is effected in the presence of a catalyst, such as a transition metal catalyst, preferably a palladium catalyst (e.g. 1 ,1 '-bis(diphenylphosphino)ferrocenepalladium(ll)chloride); a solvent, such as a polar aprotic solvent (e.g. N,N-dimethylformamide); at ambient to elevated temperature, such as around 50°C; under an inert atmosphere, such as carbon monoxide; and at elevated pressure, such as around 345 kPa.

Compounds of formula (V) may be prepared from compounds of formula (III) by derivatising the hydroxy group therein to provide a leaving group (Lg). Conveniently, Lg is a reactive ester group, such as a sulphonic ester group, (e.g. trifluoromethanesulphonate). Conveniently, the reaction is effected in the presence of a derivatising agent, such as a sulphonic amide, (e.g. phenyltriflamide); a base, such as a trialkylamine base (e.g. triethylamine); a solvent such, such as a halogenated alkane (e.g. dichloromethane); and at ambient to elevated temperature, such as ambient temperature.

Scheme 1

H„NNH-R (VI)

Compounds of formula (III) may be prepared by the reaction of a compound of formula (VII) with a hydrazine of formula (VI), or a salt or hydrate thereof. Conveniently, the reaction is effected a solvent, such as a protic solvent (e.g. acetic acid); at ambient to elevated temperature, such as ambient temperature; and optionally in the presence of an acid (e.g. acetic acid) or a base, such as a tertiary amine (e.g. triethylamine).

Compounds of formula (VII) may be prepared by the reaction of a compound of formula (IX) with an alcohol of formula (VIII). Conveniently, the reaction is effected in the presence of a solvent, such as a polar solvent (e.g. acetone); a base, such as an inorganic base, preferably a metal carbonate (e.g. potassium or caesium carbonate); optionally, a nucleophilic catalyst, such as sodium iodide or tetrabutylammonium iodide; and at ambient to elevated temperature, such as elevated temperature (e.g. under reflux).

Chloroketoesters of formula (IX) are either commercially available, known in the literature, or may be prepared by conventional methods (e.g. the chlorination of the corresponding ketoesters, for instance using sulphonyl chloride).

According to Scheme 1 , compounds of formula (I) may also be prepared by the reaction of an alcohol of formula (III) with a compound of formula (II) under conventional conditions. Conveniently, the reaction is effected in the presence of a base, such as an inorganic base, preferably a metal carbonate (e.g. potassium carbonate); optionally a solvent, such as a polar aprotic solvent (e.g. N,N- dimethylacetamide); optionally a catalyst, such as a copper(l) catalyst; and at ambient to elevated temperature, such as elevated temperature (e.g. under reflux).

Alternatively, compounds of formula (I) may be prepared from compounds of formula (III) by reaction with an alcohol of formula (IV) under dehydrating conditions, such as afforded by the Mitsunobu reaction. Conveniently, the reaction is effected in the presence of diethylazodicarboxylate, triphenylphosphine, a solvent, such as an ether, (e.g. tetrahydrofuran); and at reduced to ambient temperature, such 0°C.

Compounds of formula (I) in which R³ is halo can be prepared from a compound of formula (X)

under conventional conditions. Conveniently, the reaction is effected by an inorganic acid halide, such as an inorganic acid chloride (e.g. POCI₃); optionally in the presence of a solvent, such as a polar aprotic solvent (e.g. N,N- dimethylformamide); and at reduced to ambient temperature, such as ambient temperature.

Compounds of formula (X) may be prepared using the routes described above, mutatis mutandis.

It will be appreciated by those skilled in the art that, in many cases, compounds of formula (I) may be converted into other compounds of formula (I) by functional group transformations, including for example the following interconversions.

Compounds of formula (I) in which R² is optionally substituted C Cβ alkyl may be prepared from compounds of formula (I) in R² is H by reaction with an alkylating agent. Suitable alkylating agents include bromoacetonitrile, ethyl

4-chloroacetoacetate, methyl bromoacetate and chloroethylamine hydrochloride. Conveniently, alkylation is effected in the presence of a suitable solvent, such as an alcohol (e.g. ethanol) or a polar aprotic solvent (e.g. N,N-dimethylformamide); a base, such as a metal hydride (e.g. sodium hydride) or metal alkoxide (e.g. sodium ethoxide); and at ambient to elevated temperature, such as under reflux.

Compounds of formula (I) in which R² or R³ contains a hydroxy group may be prepared from the corresponding compound of formula (I) in which R² or R³ contains an ester group by reduction. Conveniently, the reduction is effected by a metal hydride agent, such as lithium aluminium hydride; in a solvent, such as an ether (e.g. diethyl ether); and at reduced temperature, such as from -78°C to 0°C.

Compounds of formula (I) in which R² or R³ are substituted by a heterocycle of formula R⁸ and R⁹ may be prepared by standard heterocycle-forming reactions well known to the skilled man (see, for example, Advanced Organic Chemistry, 3rd Edition, by Gerry March or Comprehensive Heterocyclic Chemistry, A.R. Katritzky, C.W. Rees, E.F.V. Scriven, Volumes 1-11 ).

Compounds of formula (I) in which R³ is -C0₂H may be prepared by hydrolysis of a corresponding compound of formula (I) in which R³ is -CO₂R⁵. Conveniently, the reaction is effected in the presence of a solvent, such as an alcohol (e.g. aqueous ethanol), or an ether (e.g. aqueous 1 ,4-dioxan); and in the presence of a base, such as a metal hydroxide (e.g. sodium hydroxide). The skilled artisan will appreciate that such an acid may be converted into a primary amide by reaction with ammonia and a suitable coupling agent, such as a carbodiimide, e.g. dicyclohexylcarbodiimide, and that such a primary amide may then be converted into a nitrile by dehydration with a suitable dehydrating agent, such as phosphoryl chloride.

Compounds of formula (I) in which R³ is d-C₆ alkyl may be converted into the compounds of formula (I) in which R³ is C C₆ alkyl substituted by halo (such as bromo), by halogenation, using a suitable halogenating agent. Conveniently the reaction is effected in the presence of a solvent, such as a haloalkane (e.g. dichloromethane) and at ambient temperature. Suitable halogenating agents include halogens (e.g. bromine) or N-halosuccinimides (e.g. N-bromsuccinimide).

Compounds of formula (I) containing an -OH, -NH- or -NH₂ group may be prepared by the deprotection of the corresponding compound bearing an -OP¹, -NP¹- or -NHP¹ group, respectively, wherein the group P¹ is a suitable protecting group. Examples of suitable protecting groups will be apparent to the skilled person; see, for instance, 'Protecting groups in Organic Synthesis (Second Edition)' by Theodora W. Green and Peter G. M. Wuts, 1991 , John Wiley and Sons. Such compounds bearing an -OP¹, -NP¹- or -NHP¹ group may be prepared using the routes described above, mutatis mutandis.

Compounds of formulae (II), (IV) and (VI) and (VIII) are either commercially available, known in the literature or easily prepared by methods well known to those skilled in the art, such as those described in the Preparations hereinafter.

Compounds of formulae (III), (V) or (X) are key intermediates and form a further aspect of the invention.

The compounds of the invention can be administered alone, but will generally be administered in admixture with a suitable pharmaceutical excipient, diluent or carrier selected with regard to the intended route of administration and standard pharmaceutical practice.

For example, the compounds of the invention can be administered orally, buccally or sublingually in the form of tablets, capsules, multi-particulates, gels, films, ovules, elixirs, solutions or suspensions, which may contain flavouring or colouring agents, for immediate-, delayed-, modified-, sustained-, pulsed- or controlled-release applications. The compounds of the invention may also be administered as fast-dispersing or fast-dissolving dosage forms or in the form of a high energy dispersion or as coated particles. Suitable formulations of the compounds of the invention may be in coated or uncoated form, as desired.

Such solid pharmaceutical compositions, for example, tablets, may contain excipients such as microcrystalline cellulose, lactose, sodium citrate, calcium carbonate, dibasic calcium phosphate, glycine and starch (preferably com, potato or tapioca starch), disintegrants such as sodium starch glycollate, croscarmellose sodium and certain complex silicates, and granulation binders such as polyvinylpyrrolidone, hydroxypropylmethylcellulose (HPMC), hydroxypropylcellulose (HPC), sucrose, gelatin and acacia. Additionally, lubricating agents such as magnesium stearate, stearic acid, glyceryl behenate and talc may be included.

General Example A formulation of the tablet could typically contain from 0.01 mg to 500mg of active compound whilst tablet fill weights may range from 50mg to 1000mg. An example of a formulation for a 10mg tablet is illustrated below:

Inqredient %w/w

Compound of the invention 10.000^*

Lactose 64.125

Starch 21.375

Croscarmellose sodium 3.000

Magnesium Stearate 1.500

Quantity adjusted in accordance with drug activity.

The tablets are manufactured by a standard process, for example, direct compression or a wet or dry granulation process. The tablet cores may be coated with appropriate overcoats.

Solid compositions of a similar type may also be employed as fillers in gelatin or HPMC capsules. Preferred excipients in this regard include lactose, starch, a cellulose, milk sugar or high molecular weight polyethylene glycols. For aqueous suspensions and/or elixirs, the compounds of the invention may be combined with various sweetening or flavouring agents, colouring matter or dyes, with emulsifying and/or suspending agents and with diluents such as water, ethanol, propylene glycol and glycerin, and combinations thereof. The compounds of the invention can also be administered parenterally, for example, intravenously, intra-arterially, intraperitoneally, intrathecally, intraventricularly, intraurethrally, intrastemally, intracranially, intramuscularly or subcutaneously, or they may be administered by infusion or needleless injection techniques. For such parenteral administration they are best used in the form of a sterile aqueous solution which may contain other substances, for example, enough salts or glucose to make the solution isotonic with blood. The aqueous solutions should be suitably buffered (preferably to a pH of from 3 to 9), if necessary. The preparation of suitable parenteral formulations under sterile conditions is readily accomplished by standard pharmaceutical techniques well- known to those skilled in the art.

For oral and parenteral administration to human patients, the daily dosage level of the compounds of the invention will usually be from 0.01 to 30 mg/kg, preferably from 0.01 to 5 mg/kg (in single or divided doses).

Thus tablets or capsules of the compound of the invention may contain from 1 to 500 mg of active compound for administration singly or two or more at a time, as appropriate. The physician in any event will determine the actual dosage which will be most suitable for any individual patient and it will vary with the age, weight and response of the particular patient. The above dosages are exemplary of the average case. There can, of course, be individual instances where higher or lower dosage ranges are merited and such are within the scope of this invention. The skilled person will appreciate that, in the treatment of certain conditions the compounds of the invention may be taken as a single dose as needed or desired.

The compounds of invention can also be administered intranasally or by inhalation and are conveniently delivered in the form of a dry powder inhaler or an aerosol spray presentation from a pressurised container, pump, spray, atomiser or nebuliser, with or without the use of a suitable propellant, e.g. dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, a hydrofluoroalkane such as 1 ,1 ,1 ,2-tetrafluoroethane (HFA 134A [trade mark]) or 1 ,1 ,1 ,2,3,3,3-heptafluoropropane (HFA 227EA [trade mark]), carbon dioxide or other suitable gas. In the case of a pressurised aerosol, the dosage unit may be determined by providing a valve to deliver a metered amount. The pressurised container, pump, spray, atomiser or nebuliser may contain a solution or suspension of the active compound, e.g. using a mixture of ethanol and the propellant as the solvent, which may additionally contain a lubricant, e.g. sorbitan trioleate. Capsules and cartridges (made, for example, from gelatin) for use in an inhaler or insufflator may be formulated to contain a powder mix of a compound of the invention and a suitable powder base such as lactose or starch.

Alternatively, the compounds of the invention can be administered in the form of a suppository or pessary, or they may be applied topically in the form of a gel, hydrogel, lotion, solution, cream, ointment or dusting powder. The compounds of the invention may also be dermally or transdermally administered, for example, by the use of a skin patch. They may also be administered by the pulmonary or rectal routes.

They may also be administered by the ocular route. For ophthalmic use, the compounds can be formulated as micronised suspensions in isotonic, pH adjusted, sterile saline, or, preferably, as solutions in isotonic, pH adjusted, sterile saline, optionally in combination with a preservative such as a benzylalkonium chloride. Alternatively, they may be formulated in an ointment such as petrolatum.

For application topically to the skin, the compounds of the invention can be formulated as a suitable ointment containing the active compound suspended or dissolved in, for example, a mixture with one or more of the following: mineral oil, liquid petrolatum, white petrolatum, propylene glycol, polyoxyethylene polyoxypropylene compound, emulsifying wax and water. Alternatively, they can be formulated as a suitable lotion or cream, suspended or dissolved in, for example, a mixture of one or more of the following: mineral oil, sorbitan monostearate, a polyethylene glycol, liquid paraffin, polysorbate 60, cetyl esters wax, cetearyl alcohol, 2-octyldodecanol, benzyl alcohol and water.

The compounds of the invention may also be used in combination with a cyclodextrin. Cyclodextrins are known to form inclusion and non-inclusion complexes with drug molecules. Formation of a drug-cyclodextrin complex may modify the solubility, dissolution rate, bioavailability and/or stability property of a drug molecule. Drug-cyclodextrin complexes are generally useful for most dosage forms and administration routes. As an alternative to direct complexation with the drug the cyclodextrin may be used as an auxiliary additive, e.g. as a carrier, diluent or solubiliser. Alpha-, beta- and gamma-cyclodextrins are most commonly used and suitable examples are described in WO91/11172, WO94/02518 and W098/55148. It is to be appreciated that all references herein to treatment include curative, palliative and prophylactic treatment.

Oral administration is preferred.

Included within the scope of the invention are embodiments comprising the co- administration of a compound of the invention with one or more additional therapeutic agents, and compositions containing a compound of the invention along with one or more additional therapeutic agents. Such a combination therapy is especially useful for the prevention and/or treatment of infection by HIV and related retroviruses which may evolve rapidly into strains resistant to any monotherapy. Alternatively, additional therapeutic agents may be desirable to treat diseases and conditions which result from or accompany the disease being treated with the compound of the invention. For example, in the treatment of an HIV or related retroviral infection, it may be desirable to additionally treat opportunistic infections, neoplasms and other conditions which occur as a result of the immuno-compromised state of the patient being treated.

Preferred combinations of the invention include simultaneous or sequential treatment with a compound of the invention and one or more:

(a) reverse transcriptase inhibitors such as abacavir, adefovir, didanosine, lamivudine, stavudine, zalcitabine and zidovudine;

(b) non-nucleoside reverse transcriptase inhibitors such as capavirine, delavirdine, efavirenz, and nevirapine;

(c) HIV protease inhibitors such as indinivir, nelfinavir, ritonavir, and saquinavir;

(d) CCR5 antagonists such as TAK-779 or UK-427,857;

(e) CXCR4 antagonists such as AMD-3100; (f) integrase inhibitors, such as L-870,810 or S-1360;

(g) inhibitors of viral fusion such as T-20;

(h) investigational drugs such as trizivir, KNI-272, amprenavir, GW-33908,

FTC, PMPA, MKC-442, MSC-204, MSH-372, DMP450, PNU-140690, ABT-378,

KNI-764, DPC-083, TMC-120 or TMC-125; (i) antifungal agents, such as fluconazole, itraconazole or voriconazole; or

(j) antibacterial agents, such as azithromycin.

The activity of the compounds of the invention as reverse transcriptase inhibitors may be measured using the following assay. Inhibition of HIV-1 reverse transcriptase enzyme

Using purified recombinant HIV-1 reverse transcriptase (RT, EC, 2.7.7.49) obtained by expression in Escherichia Coli, a 96-well plate assay system is established for assaying a large number of samples using either the Poly(rA)- oligo(dT) Reverse Transcriptase [3H]-SPA enzyme assay system (Amersham NK9020) or the [3H]-flashplate enzyme assay system (NEN - SMP 103) and following the manufacturer's recommendations. The compounds are dissolved in 100% DMSO and diluted with the appropriate buffer to a 5% final DMSO concentration. The inhibitory activity is expressed in percent inhibition relative to DMSO control. The concentration at which compound inhibits reverse transcriptase by 50% is expressed as the IC₅₀ of the compound.

The compound of Exampls 1 and 6, when tested according to the above procedure, had an IC50 values of, respectively, 5400 and 391 nanomolar.

Thus the invention provides:

(i) a compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof; (ii) a process for the preparation of a compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof; (iii) a pharmaceutical composition including a compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof, together with a pharmaceutically acceptable excipient, diluent or carrier; (iv) a compound of formula (I) or a pharmaceutically acceptable salt, solvate or composition thereof, for use as a medicament; (v) a compound of formula (I) or a pharmaceutically acceptable salt, solvate or composition thereof, for use as a reverse transcriptase inhibitor or modulator; (vi) a compound of formula (I) or a pharmaceutically acceptable salt, solvate or composition thereof, for use in the treatment of an HIV or genetically- related retroviral infection, or a resulting acquired immune deficiency syndrome (AIDS); (vii) a use of the compound of formula (I) or of a pharmaceutically acceptable salt, solvate or composition thereof, for the manufacture of a medicament having reverse transcriptase inhibitory or modulating activity; (viii) the use of a compound of formula (I) or of a pharmaceutically acceptable salt, solvate or composition thereof, for the manufacture of a medicament for the treatment of an HIV or genetically-related retroviral infection, or a resulting acquired immune deficiency syndrome (AIDS);

(ix) a method of treating an HIV or a genetically-related retroviral infection, or a resulting acquired immune deficiency syndrome (AIDS), comprising administering an effective amount of a compound of formula (I) or a pharmaceutically acceptable salt, solvate or composition thereof; and (xi) certain novel intermediates disclosed herein. The following Examples illustrate the preparation of the compounds of formula (I). The synthesis of certain intermediates used therein are described in the Preparations section that follows the Examples.

¹H Nuclear magnetic resonance (NMR) spectra were in all cases consistent with the proposed structures. Characteristic chemical shifts (δ) are given in parts-per- million downfield from tetramethylsilane using conventional abbreviations for designation of major peaks: e.g. s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; br, broad. The following abbreviations have been used: HRMS, high resolution mass spectrometry; hplc, high performance liquid chromatography; nOe, nuclear Overhauser effect; m.p., melting point; CDCI₃, deuterochloroform; D₆-DMSO, deuterodimethylsulphoxide; CD₃OD, deuteromethanol. Where thin layer chromatography (TLC) has been used it refers to silica gel TLC using silica gel 60 F₂₅₄ plates, R_f is the distance travelled by a compound divided by the distance travelled by the solvent front on a TLC plate.

Example 1

5-r3-Ethyl-1-methyl-5-(pyridin-2-yloxy)-1 /-/-Pyrazol-4-yloxy1-isophthalonitrile

The pyrazole of Preparation 5 (10 mg, 0.37 mmol) and 2-chloropyridine (55 mg, 0.49 mmol) were mixed and heated to 145°C for 1.5 hours. The mixture was cooled to room temperature and partitioned between ethyl acetate (10 ml) and water (10 ml). The aqueous solution was extracted with ethyl acetate (2x10 ml). The combined organic solutions were evaporated under reduced pressure and the residue was purified by chromatography on silica gel using methanol in dichloromethane (1 :99) to give the title compound as a yellow solid (30 mg).

¹H NMR (400 MHz, CD₃OD): δ 1.18 (m, 3H), 2.49 (m, 2H), 3.60 (s, 3H), 7.00 (m, 1 H), 7.15 (m, 1 H), 7.6 (s, 2H), 7.72 (m, 1 H), 7.80 (m, 1 H), 8.12 (m, 1 H). LRMS (APCI): m/z [M+H]⁺ 346

Examples 2-10:

The compounds of Table 1 of the general formula:

were prepared by a method analogous to that of Example 1 using the appropriate pyrazole and aryl halide. Table 1

A, starting pyrimidine, see J. Het. Chem, 1980, 17(7) 1479.

B, starting pyrimidine supplied by Peakdale Fine Chemicals Example 2

¹H NMR (400 MHz, DMSO-d₆): δ 1.10 (m, 3H), 2.40 (m, 2H), 3.6 (s, 3H), 7.38 (m, 1 H), 7.8 (s, 2H), 8.05 (s, 1 H), 8.62 (m, 2H). LRMS (APCI): m/z [M+H]⁺ 347

Example 3:

¹H NMR (400 MHz, CDCI₃): δ 1.26 (m, 6H), 2.48 (m, 2H), 2.64 (m, 2H), 3.70 (s, 3H), 7.50 (m, 3H), 8.38 (m, 2H) LRMS (APCI): m/z [M+H]⁺ 375.

Example 4:

¹H NMR (400 MHz, CDCI₃): δ 1.20 (m, 3H), 2.48 (m, 2H), 3.75 (s, 3H), 7.50 (m,

8H), 8.70 (m, 2H).

LRMS (APCI): m/z[M+H]⁺ 423

Example 5:

¹H NMR (400 MHz, CDCI₃): δ 1.20 (m, 3H), 2.49 (m, 2H), 3.15 (m, 6H), 3.70 (s, 3H), 6.23 (m, 1 H), 7.45 (m, 2H), 8.00 (m, 2H). LRMS (APCI): m/z [M+H]⁺ 390

Example 6:

¹H NMR (400 MHz, CDCI₃): δ 1.20 (m, 3H), 2.48 (m, 2H), 3.82 (s, 3H),3.85 (s, 3H), 6.95 (m, 4H), 7.42 (s, 2H), 7.52 (s, 1 H), 8.20 (s, 2H). LRMS (APCI): m/z [M+H]⁺ 469

Example 7:

¹H NMR (400 MHz, CDCI₃): δ 1.20 (m, 3H), 2.48 (m, 2H), 3.70 (s, 3H), 7.42 (s, 2H), 7.50 (s, 1 H), 8.00 (s, 1 H), 8.38 (s, 1 H), 8.42 (s, 1 H). LRMS (APCI): m/z [M+H]⁺ 347

Example 8: H NMR (400 MHz, CDCI₃): δ 1.20 (m, 3H), 2.48 (m, 2H), 3.80 (s, 3H), 6.80 (m, 1 H), 7.10 (m, 1 H), 7.42 (s, 2H), 7.50 (s, 1 H). LRMS (APCI): m/z [M+H]⁺ 352

Example 9:

¹H NMR (400 MHz, DMSO0-d₆): δ 1.10 (m, 3H), 2.47 (m, 2H), 3.0 (m, 2H), 4.20 (m, 2H), 7.38 (m, 1 H), 7.5 (s, 2H), 8.05 (s, 1 H), 8.60 (m, 2H). LRMS (APCI): m/z [M+H]⁺ 386 Example 10:

¹H NMR (400 MHz, CDCI₃): δ 1.20 (m, 3H), 2.54 (m, 2H), 5.2 (s, 2H), 7.00 (m, 1 H), 7.15-7.25 (m, 5H), 7.5 (s, 3H), 8.4 (m, 2H). LRMS (APCI): m/z [M+H]⁺ 423

Example 11

5-f3-Ethyl-1-(2-hvdroxy-ethyl)-5-(pyridin-2-yloxy)-1 H-Pyrazol-4-yloxy1- isophthalonitrile

Tetrabutylammonium fluoride (1 M in tetrahydrofuran, 72 μl, 0.07 mmol) was added to a solution of the silyl ether of Preparation 10 (32 mg, 0.07 mmol) in tetrahydrofuran (3 ml) and the mixture was stirred for 1.5 hours. A further quantity of tetrabutylammonium fluoride (1 M in tetrahydrofuran, 33 μl, 0.03 mmol) was added and the mixture was stirred for a further 45 minutes. Brine and dichloromethane were added and the layers were separated. The organic layer was dried over magnesium sulphate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel using methanol in dichloromethane (gradient from 2:98 to 3.5:96.5) to give the title compound as a yellow oil (21 mg).

¹H NMR (400 MHz, CDCI₃): δ 1.18 (m, 3H), 2.49 (m, 2H), 4.07 (m, 4H), 6.90 (m, 1 H), 7.10 (m, 1 H), 7.45 (m, 3H), 7.60 (m, 1 H), 8.10 (m, 1 H). LRMS (APCI): m/z [M+H]⁺ 376. Preparation 1

1.S-Dibromo-S-methoxybenzene

Sodium methoxide (4.5M solution in methanol, 8.80 ml, 41.0 mmol) was added dropwise to a stirred solution of 3,5-dibromofluorobenzene (5.00 g, 19.0 mmol, Aldrich) in Λ/,Λ/-dimethylformamide (95 ml) at 0°C under a nitrogen atmosphere. The reaction was warmed to room temperature, stirred for 1 hour and then evaporated under reduced pressure. The residue was dissolved in diethyl ether and was washed with water (3x300 ml) and brine (300 ml), dried over magnesium sulphate, filtered and concentrated under reduced pressure to give the title compound as a white solid (5.13 g). ¹H-NMR (300MHz, CDCI₃): δ 3.79 (s, 3H), 7.00 (s, 2H), 7.26 (s, 1 H). LRMS: m/z TS+ 266 [M+H] ⁺

Preparation 2

3,5-Dicvanomethoxybenzene

Tris(dibenzylideneacetone)dipalladium(0) (6.53g, 7.15mmol) was added in one portion to a stirred solution of the bromide of Preparation 1 (38.0g, 143mmol), 1 ,1'-bis(diphenylphosphino)ferrocene (9.3g, 16.8mmol) and zinc cyanide (20. Og, 172mmol) in Λ/./V-dimethylformamide (300ml) at room temperature under nitrogen. The reaction was heated at 100°C for 14 hours and cooled to room temperature. Water (1500ml) was added and the mixture was extracted with ethyl acetate (3x500ml). The combined organics were filtered and the filtrate was washed with water (500ml), dried over magnesium sulphate, filtered and concentrated under reduced pressure. The resulting solid was triturated with toluene (1000ml) to provide the title compound (18.0α) as a tan solid. ¹H-NMR (300MHz, CDCI₃): δ = 3.83 (3H, s), 7.31 (2H, s), 7.48 (1 H, s). Preparation 3

3.5-Dicvanohvdroxybenzene

The ether of Preparation 2 (9.60 g, 60.7 mmol) was added portionwise to a stirred suspension of aluminium trichloride (32.4 g, 243 mmol) in dichloromethane (250 ml) at 0°C under a nitrogen atmosphere. The suspension was stirred at 45°C for 6 days, then cooled to room temperature and poured onto ice (450 ml). Concentrated hydrochloric acid (450 ml) was added dropwise and the resulting suspension was stirred for 10 minutes at room temperature. The solid formed was isolated by filtration, washed with water and dried over phosphorus pentoxide to give the title compound as a tan solid (7.83 g).

¹H-NMR (400MHz, CDCI₃): δ 7.36 (m, 2H), 7.56 (m, 1 H).

Preparation 4

2-(3.5-Dicyano-phenoxy)-3-oxo-pentanoic acid methyl ester

A solution of 2-chloro-3-oxo-pentanoic acid methyl ester (20 g, 121.5 mmol) in acetone (100 ml) was added to the phenol from Preparation 3 (17.5 g, 121.5 mmol) and caesium carbonate (43.5 g, 133.6 mmol) in acetone (400 ml) under a nitrogen atmosphere. The mixture was stirred at room temperature for 15 minutes and then heated under reflux for 2.5 hours. Water was added and the solvent was evaporated under reduced pressure. The residual aqueous solution was extracted with dichloromethane (3x300 ml) and the combined organic layers were dried over magnesium sulphate and evaporated under reduced pressure. The residual orange oil was pre-adsorbed onto silica gel and then purified by chromatography on silica gel using ethyl acetate in pentane (gradient from 20:80 to 80:20) to give the title compound as a yellow solid (27 g).

M.p. 93-95°C

Found; C, 61.57; H, 4.54; N, 10.06; Cι₄Hι₂N₂O₄ requires C, 61.76; H, 4.44; N, 10.29%.

Preparation 5

5-(3-Ethyl-1-methyl-5-oxo-4,5-dihvdro-1 H-pyrazol-4-yloxy)-isophthalonitrile

The ester from Preparation 4 (4 g, 14.7 mmol) was dissolved in acetic acid (50 ml) and methyl hydrazine (0.87 ml, 16.2 mmol) was added. The mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours and the solvent was evaporated under reduced pressure. The residue was triturated with diethyl ether to give the title compound as a pink solid (2.75 g).

M. p. 235-dec

LRMS: m/z ES+ 269 [M+H] ⁺ Preparation 6

5-f1-(2-Cvano-ethvπ-3-ethyl-5-oxo-4.5-dihvdro-1 H-pyrazol-4-yloxy1- isophthalonitrile

The title compound was obtained from the ester of preparation 4 and 3- hydrazino-propionitrile in 57% yield following a procedure analogous to that described in Preparation 5.

M.p. 203.5-204.5°C

APCI MS m/z 308 [M+H]⁺

Preparation 7

5-f3-Ethyl-1-(2-hvdroxy-ethvπ-5-oxo-4.5-dihvdro-1 H-pyrazol-4-yloxyl- * isophthalonitrile

The title compound was obtained in 73% yield from the ester of preparation 4 and 2-hydrazino-ethanol following a procedure analogous to that described in Preparation 5. M.p. 203.5-204.5°C APCI MS m/z 297 [M-H]^" Preparation 8

5-(1 -Benzyl-3-ethyl-5-oxo-4.5-dihvdro-1 H-pyrazol-4-yloxy)-isophthalonitrile

The title compound was obtained from the ester of preparation 4 and benzyl hydrazine in 52% yield following a procedure analogous to that described in Preparation 5.

APCI MS m/z 345 [M+H]⁺

Preparation 9

5-(1 -r2-(fert-Butyl-dimethyl-silanyloxy)-ethyl1-3-ethyl-5-oxo-4.5-dihvdro-1 /-/- pyrazol-4-yloxy)-isophthalonitrile

tert-Butyl-dimethyl-silyl chloride (2.4 g, 16.1 mmol) was added to a solution of the alcohol of preparation 7 (4.0 g, 13.4 mmol) in N,N-dimethylformamide (20 ml) and triethylamine (5.6 ml, 40.3 mmol). The mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours and then was partitioned between ethyl acetate and water. The organic layer was washed with brine (2x100 ml) dried over magnesium sulphate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel using dichloromethane as eluant to give the title compound (3.6 g).

M.p. 203.5-204.5°C

APCI MS m/z413 [M+H]⁺

Preparation 10

5-π-f2-(fet -Butyl-dimethyl-silanyloxy)-ethvn-3-ethyl-5-(pyridin-2-yloxy)-1 -/- pyrazol-4-yloxyl-isophthalonitrile

A mixture of the pyrazole of preparation 9 (150 mg, 0.36 mmol) and 2- chloropyridine (54 mg, 0.47 mmol) was heated to 150°C for 2 hours and then was partitioned between ethyl acetate and water. The organic layer was evaporated under reduced pressure and the residue was purified by chromatography on silica gel using methanol in dichloromethane as eluant (2:98) to give the title compound (32 mg).

LCMS: m/z ES⁺ 512 [M+Na]⁺

Claims

1. A compound of formula (I)

or a pharmaceutically acceptable salt, solvate or derivative thereof, wherein:

R¹ is a five or six-membered, aromatic heterocyclic group containing (i) from 1 to 4 nitrogen heteroatom(s) or (ii) 1 or 2 nitrogen heteroatom(s) and 1 oxygen or 1 sulphur heteroatom or (iii) 1 or 2 oxygen or sulphur heteroatom(s), said heterocyclic group being optionally substituted by halo, oxo, -CN, -COR⁵, -CONR⁵R⁵, -S0₂NR⁵R⁵, -NR⁵S0₂R⁵, -OR⁵, OR¹¹, -NR⁵R⁵,

-(Ci-C₆ alkylene)-NR⁵R⁵, R⁷ or R¹¹;

R² is H, Ci-C₆ alkyl, C₃-C₆ alkenyl, C₃-C₆ alkynyl, C₃-C₇ cycloalkyl, C_3-C cycloalkenyl, phenyl, benzyl, R⁸ or R⁹, said d-C₆ alkyl, C₃-C₇ cycloalkyl, phenyl and benzyl being optionally substituted by halo, -OR⁵, -OR¹⁰, -CN, -C0₂R⁷, -OCONR⁵R⁵, -CONR⁵R⁵, -C(=NR⁵)NR⁵OR⁵, -CONR⁵NR⁵R⁵, -NR⁶R⁶, -NR⁵R¹⁰, -NR⁵COR⁵, -NR⁵COR⁸, -NR⁵COR¹⁰, -NR⁵C0₂R⁵, -NR⁵CONR⁵R⁵, -S0₂NR⁵R⁵, -NR⁵S0₂R⁵, -NR⁵S0₂NR⁵R⁵, R⁸ or R⁹;

R³ is H, d-Ce alkyl, C₃-C₇ cycloalkyl, phenyl, benzyl, halo, -CN, -OR⁷, -C0₂R⁵, -CONR⁵R⁵, R⁸ or R⁹, said C C₆ alkyl, C₃-C₇ cycloalkyl, phenyl and benzyl being optionally substituted by halo, -CN, -OR⁵, -C0₂R⁵, -CONR⁵R⁵, -OCONR⁵R⁵, -NR⁵CO₂R⁵, -NR⁶R⁶, -NR⁵COR⁵, -S0 NR⁵R⁵, -NR⁵CONR⁵R⁵, -NR⁵S0₂R⁵, R⁸ or R⁹;

R⁴ is phenyl, naphthyl or pyridyl, each being optionally substituted by R⁸, halo, -CN, d-Ce alkyl, C C₆ haloalkyl, C₃-C₇ cycloalkyl, C C₆ alkoxy, -CONR⁵R⁵, OR¹¹, So_xR⁶, O-(d-C₆ alkylene)-CONR⁵R⁵, 0-(d-C₆ alkylene)-NR⁵R⁵, or 0-(Cι-C₆ alkylene)-OR⁶;

each R⁵ is independently either H, CrC₆ alkyl or C₃-C cycloalkyl or, when two R⁵ groups are attached to the same nitrogen atom, those two groups taken together with the nitrogen atom to which they are attached represent azetidinyl, pyrrolidinyl, piperidinyl, homopiperidinyl, piperazinyl, homopiperazinyl or morpholinyl, said azetidinyl, pyrrolidinyl, piperidinyl, homopiperidinyl, piperazinyl, homopiperazinyl and morpholinyl being optionally substituted by CrC₆ alkyl or C₃-C₇ cycloalkyl;

each R⁶ is independently either H, CrC₆ alkyl or C₃-C cycloalkyl;

R⁷ is CrC₆ alkyl or C₃-C₇ cycloalkyl;

R⁸ is a five or six-membered, aromatic heterocyclic group containing (i) from 1 to 4 nitrogen heteroatom(s) or (ii) 1 or 2 nitrogen heteroatom(s) and 1 oxygen or 1 sulphur heteroatom or (iii) 1 or 2 oxygen or sulphur heteroatom(s), said heterocyclic group being optionally substituted by halo, oxo, -CN, -COR⁵, -CONR⁵R⁵, -SO₂NR⁵R⁵, -NR⁵S0₂R⁵, -OR⁵, -NR⁵R⁵, -(C C₆ alkylene)-NR⁵R⁵, Cι-C₆ alkyl, fluoro(CrC₆)alkyl or C₃-C₇ cycloalkyl;

R⁹ is a four to seven-membered, saturated or partially unsaturated heterocyclic group containing (i) 1 or 2 nitrogen heteroatom(s) or (ii) 1 nitrogen heteroatom and 1 oxygen or 1 sulphur heteroatom or (iii) 1 oxygen or sulphur heteroatom, said heterocyclic group being optionally substituted by oxo, CrC₆ alkyl, C₃-C₇ cycloalkyl, -S0₂R⁵, -CONR⁵R⁵, -COOR⁵, -CO-(C_rC₆ alkylene)-OR⁵ or -COR⁵ and optionally substituted on a carbon atom which is not adjacent to a heteroatom by halo, -OR⁵, -NR⁵R⁵, -NR⁵COR⁵, -NR⁵COOR⁵, -NR⁵CONR⁵R⁵, -NR⁵S0₂R⁵ or -CN;

R¹⁰ is d-Ce alkyl substituted by R⁸, R⁹, -OR⁵, -CONR⁵R⁵, -NR⁵COR⁵ or -NR⁵R⁵;

R¹¹ is phenyl optionally substituted by halo, -CN, -COR⁵, -CONR⁵R⁵, -S0₂NR⁵R⁵, -NR⁵S0₂R⁵, -OR⁵, -NR⁵R⁵, -(Cι-C₆ alkylene)-NR⁵R⁵, C C_β alkyl, halo(d-C₆)alkyl or C3-C7 cycloalkyl; and

x is O, 1 or 2.

2. A pharmaceutical composition including a compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof together with one or more pharmaceutically acceptable excipients, diluents or carriers.

3. A pharmaceutical composition according to claim 2 including one or more additional therapeutic agents.

4. A compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof, or a pharmaceutical composition according to claim 2 or 3, for use as a medicament.

5. A compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof, or a pharmaceutical composition according to claim 2 or 3, for use as a reverse transcriptase inhibitor or modulator.

6. A compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof, or a pharmaceutical composition according to claim 2 or 3, for use in the treatment of an HIV or genetically-related retroviral infection, or a resulting acquired immune deficiency syndrome (AIDS).

7. Use of a compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof, or a pharmaceutical composition according to claim 2 or 3, for the manufacture of a medicament having reverse transcriptase inhibitory or modulating activity.

8. Use of a compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof, or a pharmaceutical composition according to claim 2 or 3, for the manufacture of a medicament for the treatment of an HIV or genetically-related retroviral infection, or a resulting acquired immune deficiency syndrome (AIDS).

9. A method of treating an HIV or a genetically-related retroviral infection, or a resulting acquired immune deficiency syndrome (AIDS), comprising administering an effective amount of a compound of formula (I) or a pharmaceutically acceptable salt, solvate or derivative thereof, or a pharmaceutical composition according to claim 2 or 3.

10. A process for preparing the compound of formula (I) or a salt, solvate or pharmaceutically acceptable derivative thereof, which comprises: (A) reaction of a compound of formula (V)

with an alcohol of formula (IV), R¹-OH (IV), under conventional conditions;

(B) reaction of an alcohol of formula (III)

with a compound of formula (II), Lg-R¹ (II), under conventional conditions;

(C) reaction of a compound of formula (III) with an alcohol of formula (IV) under dehydrating conditions;

(D) for the preparation of a compound of formula (I) in which R³ is halo, halogenating a compound of formula (X)

under conventional conditions;

(E) interconversion of a compound of formula (I) into another compound of formula (I); or

(F) deprotecting a protected derivative of compound of formula (I); and optionally converting a compound of formula (I) prepared by any one of processes (A) to (F) into pharmaceutically acceptable salt, solvate or derivative thereof.

11. A compound of formulae (III), (IV) or (X).