WO2001087850A1

WO2001087850A1 - Pyridazine derivative elevating pdhactivity

Info

Publication number: WO2001087850A1
Application number: PCT/GB2001/002111
Authority: WO
Inventors: Roger John Butlin; Thorsten Nowak; Jeremy Nicholas Burrows; Michael Howard Block; Suzanne Saxon Bowker
Original assignee: Astrazeneca Ab; Astrazeneca Uk Limited
Priority date: 2000-05-19
Filing date: 2001-05-15
Publication date: 2001-11-22
Also published as: GB0012012D0; AU2001254989A1

Abstract

The compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof is described. Also described are processes for its preparation, pharmaceutical compositions containing it and its use in producing an elevation of PDH activity in a warm-blooded animal.

Description

PYRIDAZINE DERIVATIVE ELEVATING PDHACTIVITY

The present invention relates to a compound which elevates pyruvate dehydrogenase (PDH) activity, processes for its preparation, pharmaceutical compositions containing it as the active ingredient, methods for the treatment of disease states associated with reduced PDH activity, to their its as a medicament and to its use in the manufacture of medicaments for use in the elevation of PDH activity in warm-blooded animals such as humans, in particular the treatment of diabetes mellitus, peripheral vascular disease and myocardial ischaemia in warmblooded animals such as humans, more particularly to its use in the manufacture of medicaments for use in the treatment of diabetes mellitus in warm-blooded animals such as humans.

Within tissues adenosine triphosphate (ATP) provides the energy for synthesis of complex molecules and, in muscle, for contraction. ATP is generated from the breakdown of energy-rich substrates such as glucose or long chain free fatty acids. In oxidative tissues such as muscle the majority of the ATP is generated from acetyl Co A which enters the citric acid cycle, thus the supply of acetyl CoA is a critical determinant of ATP production in oxidative tissues. Acetyl CoA is produced either by β-oxidation of fatty acids or as a result of glucose metabolism by the glycolytic pathway. The key regulatory enzyme in controlling the rate of acetyl CoA formation from glucose is PDH which catalyses the oxidation of pyruvate to acetyl CoA and carbon dioxide with concomitant reduction of nicotinamide adenine dinucleotide (NAD) to NADH.

In disease states such as both non-insulin dependent (NIDDM) and insulin-dependent diabetes mellitus (IDDM), oxidation of lipids is increased with a concomitant reduction in utilisation of glucose, which contributes to the hyperglycaemia. Reduced glucose utilisation in both IDDM and NIDDM is associated with a reduction in PDH activity. In addition, a further consequence of reduced PDH activity may be that an increase in pyruvate concentration results in increased availability of lactate as a substrate for hepatic gluconeogenesis. It is reasonable to expect that increasing the activity of PDH could increase the rate of glucose oxidation and hence overall glucose utilisation, in addition to reducing hepatic glucose output. Another factor contributing to diabetes mellitus is impaired insulin secretion, which has been shown to be associated with reduced PDH activity in pancreatic β-cells (in a rodent genetic model of diabetes mellitus Zhou et al. (1996) Diabetes 45: 580-586). Oxidation of glucose is capable of yielding more molecules of ATP per mole of oxygen than is oxidation of fatty acids. In conditions where energy demand may exceed energy supply, such as myocardial ischaemia, intermittent claudication, cerebral ischaemia and reperfusion, (Zaidan et al., 1998; I. Neurochem. 70: 233-241), shifting the balance of 5 substrate utilisation in favour of glucose metabolism by elevating PDH activity may be expected to improve the ability to maintain ATP levels and hence function.

An agent which is capable of elevating PDH activity may also be expected to be of benefit in treating conditions where an excess of circulating lactic acid is manifest such as in certain cases of sepsis.

10 The agent dichloroacetic acid (DC A) which increases the activity of PDH after acute administration in animals, (Nary et al., 1988; Circ. Shock, 24: 3-18), has been shown to have the predicted effects in reducing glycaemia, (Stacpoole et al., 1978; Ν. Engl. I. Med. 298: 526-530), and as a therapy for myocardial ischaemia (Bersin and Stacpoole 1997; American Heart Journal, 134: 841-855) and lactic acidaemia, (Stacpoole et al, 1983; Ν. Engl. J. Med.

15 309: 390-396).

PDH is an intramitochondrial multienzyme complex consisting of multiple copies of several subunits including three enzyme activities El, E2 and E3, required for the completion of the conversion of pyruvate to acetyl CoA (Patel and Roche 1990; FASEB J., 4: 3224-3233). El catalyses the non-reversible removal of CO₂ from pyruvate; E2 forms acetyl CoA and E3

20 reduces NAD to NADH. Two additional enzyme activities are associated with the complex: a specific kinase which is capable of phosphorylating El at three serine residues and a loosely-associated specific phosphatase which reverses the phosphorylation. Phosphorylation of a single one of the three serine residues renders the El inactive. The proportion of the PDH in its active (dephosphorylated) state is determined by a balance between the activity of the kinase

25 and phosphatase. The activity of the kinase may be regulated in vivo by the relative concentrations of metabolic substrates such as NAD/NADH, CoA/acetylCoA and adenine diphosphate (ADP)/ATP as well as by the availability of pyruvate itself.

A compound that elevates PDH activity may potentially have value in the treatment of disease states associated with disorders of glucose utilisation such as diabetes mellitus, obesity,

30 (Curto et al., 1997; Int. J. Obes. 21: 1137-1142), and lactic acidaemia. Additionally the compound may be expected to have utility in diseases where supply of energy-rich substrates to tissues is limiting such as peripheral vascular disease, (including intermittent claudication), cardiac failure and certain cardiac myopathies, muscle weakness, hyperlipidaemias and atherosclerosis (Stacpoole et al, 1978; N. Engl. J. Med. 298: 526-530). A compound that activates PDH may also be useful in treating Alzheimer's disease (AD) (J Neural Transm (1998) 105, 855-870).

European Patent Publication Nos. 617010 and 524781 describes compounds which are capable of relaxing bladder smooth muscle and which may be used in the treatment of urge incontinence. International Applications WO 9944618, WO 9947508, WO 9962506 and WO 9962873 describe compound that elevate PDH. The compound of the present invention falls within the broad scope of WO 9962506, but is not specifically disclosed therein and we have surprisingly found that this compound possesses advantageous properties and is particularly efficacious in the elevation of PDH activity.

Accordingly the present invention provides the compound of formula (I):

(I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof. The compound of formula (I) is conveniently named:

(R)-N- [4- { 6-morpholinopyridazin-3 -ylsulphonyl } -2-chlorophenyl] -2-hydroxy-2-methyl-3 ,3,3- trifluoropropanamide.

Preferred aspects of the invention are those which relate to the compound or a pharmaceutically acceptable salt thereof. It is also to be understood that the compound of formula (I) and its pharmaceutically acceptable salts and in vivo hydrolysable esters thereof can exist in solvated as well as unsolvated forms such as, for example, hydrated forms. It is to be understood that the invention encompasses all such solvated forms which elevate PDH activity.

The compound of formula (I) and its pharmaceutically acceptable salts and in vivo hydrolysable esters thereof may be prepared by any process known to be applicable to the preparation of chemically related compounds. Such processes include, for example, those illustrated in European Patent Applications, Publication Νos. 0524781, 0617010, 0625516, and in GB 2278054 and in International Applications WO 9323358, WO 9738124, WO 9944618, WO 9947508, WO 9962506 and WO 9962873. Another aspect of the present invention provides a process for preparing the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, which process (in which variable groups are as defined for formula (I) unless otherwise stated) comprises of: (a) deprotecting a protected compound of formula (II):

(II) where Pg is an alcohol protecting group; (b) oxidising the compound of formula (III):

(HI)

(c) coupling the compound of formula (IN):

(IN) with an acid of formula (V):

wherein X is OH;

(d) coupling an aniline of formula (IN) with an activated acid derivative of formula (V); and thereafter if necessary: i) separating a mixture of enantiomers to give the (R)-enantiomer; ii) removing any protecting groups; or iii) forming a pharmaceutically acceptable salt or in vivo hydrolysable ester. Suitable values for Pg are a benzyl group, a silyl group (for example a trialkylsilyl group or an alkyldiphenylsilyl group) or an acetyl protecting group.

Where formula (N) is an activated acid derivative, suitable values for X include halo (for example chloro or bromo), anhydrides, aryloxys (for example 4-nitrophenoxy or pentafluorophenoxy) or imidazol-1-yl. Specific conditions of the above reactions are as follows:

Process a)

Examples of suitable reagents for deprotecting an alcohol of formula (II) are:

1) when Pg is benzyl:

(i) hydrogen in the presence of palladium/carbon catalyst, i.e. hydro genolysis; or (ii) hydrogen bromide or hydrogen iodide;

2) when Pg is a silyl protecting group: (i) tetrabutylammonium fluoride; or (ii) aqueous hydrofluoric acid;

3) when Pg is acetyl: i) mild aqueous base for example lithium hydroxide; or ii) ammonia or an amine such as dimethylamine.

The reaction can be conducted in a suitable solvent such as ethanol, methanol, acetonitrile, or dimethylsulphoxide and may conveniently be performed at a temperature in the range of -40 to 100°C. Compounds of formula (II) may be prepared according to the following scheme: HO Me

O /r OOIH (Ha)

Scheme 1

E is a carboxy protecting group. Suitable values for E include -βalkyl, such as methyl and ethyl. The compound of formula (Ha) is a commercially available compound, it is known in the literature and may also be prepared by standard processes known in the art. The synthesis of the compound of formula (IV) is described below. Process b

Suitable oxidising agents include potassium permanganate, OXOΝE, sodium periodate, tert-butyl hydroperoxide (as solution in toluene), peracids (such as for example 3-chloroperoxybenzoic acid), hydrogen peroxide, TPAP (tetrapropylammonium perruthenate) or oxygen. The reaction may be conducted in a suitable solvent such as diethyl ether, dichloromethane, methanol, ethanol, water, acetic acid, or mixtures of two or more of these solvents. The reaction may conveniently be performed at a temperature in the range of -40 to 100°C.

The compound of formula (III) may be prepared according to the following schemes:

IC1

ii) Pd(0), NaOMe, DMF, A (IIIc)

Scheme 2

The skilled reader will appreciate that the order of steps 1 and 2 in Scheme 2 may be reversed.

(III) iii) Deprotection

Scheme 3

Compounds of formula (Ilia), (III*), (III**) and (Hid) are commercially available compounds, or they are known in the literature, or they are prepared by standard processes known in the art. Process c)

The reaction can be conducted in the presence of a suitable coupling reagent. Standard peptide coupling reagents known in the art can be employed as suitable coupling reagents, for example conditions such as those described above for the coupling of (Ilia) and (V) or (Hid) and (Hd), or for example dicyclohexyl-carbodiimide, optionally in the presence of a catalyst such as dimethylaminopyridine or 4-pyrrolidinopyridine, optionally in the presence of a base for example triethylamine, pyridine, or 2,6-di- Zfcy/-pyridines (such as 2,6-lutidine or 2,6-di-tert-butylpyridine) or 2,6-diphenylpyridine. Suitable solvents include dimethylacetamide, dichloromethane, benzene, tetrahydrofuran, and dimethylformamide. The coupling reaction may conveniently be performed at a temperature in the range of -40 to 40°C. The compound of formula (IN) may be prepared according to the following scheme:

Scheme 3

The compounds of formula (INa) and (V) are commercially available compounds, or they are known in the literature, or they are prepared by standard processes known in the art. Process d)

This coupling may be achieved optionally in the presence of a base for example triethylamine, pyridine, 2,6-di-αZfcyZ-pyridines (such as 2,6-lutidine or 2,6-di-tert-butylpyridine) or 2,6-diphenylpyridine. Suitable solvents include dimethylacetamide, dichloromethane, benzene, tetrahydrofuran, and dimethylformamide. The coupling reaction may conveniently be performed at a temperature in the range of -40 to 40°C.

The required optically active form of the compound of formula (I) if not obtained by carrying out one of the above procedures using an optically active starting materials (formed, for example, by asymmetric induction of a suitable reaction step) may be obtained by resolution of a mixture of the compound of formula (I) and its corresponding (S) enantiomer or of any intermediate using a standard procedure, or by chromatographic separation of enantiomers (when produced). For example, if the resolved acid of formula (V) is required, it may be prepared by any of the known methods for preparation of optically-active forms (for example, by recrystallization of the chiral salt {for example WO 9738124}, by enzymatic resolution or by chromatographic separation using a chiral stationary phase). For example if an (R)-(+) resolved acid is required it may be prepared by the method of Scheme 2 in World Patent Application Publication No. WO 9738124 for preparation of the (S)-(-) acid, i.e. using the classical resolution method described in European Patent Application Publication No. EP 0524781, also for preparation of the (S)-(-) acid, except that (lS,2R)-norephedrine may be used in place of (S)-(-)-l-phenylethylamine. The chiral acid may also be prepared by using the enzymatic resolution method as described in Tetrahedron Asymmetry, 1999, 10, 679.

If not commercially available, the necessary starting materials for the procedures such as that described above may be made by procedures which are selected from standard organic chemical techniques, techniques which are analogous to the synthesis of known, structurally similar compounds, or techniques which are analogous to the above described procedure or the procedures described in the examples.

It is noted that many of the starting materials for synthetic methods as described above are commercially available and/or widely reported in the scientific literature, or could be made from commercially available compounds using adaptations of processes reported in the scientific literature. The reader is further referred to Advanced Organic Chemistry, 4^th Edition, by Jerry March, published by John Wiley & Sons 1992, for general guidance on reaction conditions and reagents.

It will also be appreciated that in some of the reactions mentioned herein it may be necessary/desirable to protect any sensitive groups in the compounds. The instances where protection is necessary or desirable and suitable methods for protection are known to those skilled in the art. Conventional protecting groups may be used in accordance with standard practice (for illustration see T.W. Green, Protective Groups in Organic Synthesis, John Wiley and Sons, 1991). Examples of a suitable protecting group for a hydroxy group is, for example, an acyl group, for example an alkanoyl group such as acetyl, an aroyl group, for example benzoyl, or an arylmethyl group, for example benzyl. The deprotection conditions for the above protecting groups will necessarily vary with the choice of protecting group. Thus, for example, an acyl group such as an alkanoyl or an aroyl group may be removed, for example, by hydrolysis with a suitable base such as an alkali metal hydroxide, for example lithium or sodium hydroxide. Alternatively an arylmethyl group such as a benzyl group may be removed, for example, by hydrogenation in the presence of a catalyst such as palladium-on-carbon.

The protecting groups may be removed at any convenient stage in the synthesis using conventional techniques well known in the chemical art. The compound of formula (I) may form stable acid or basic salts, and in such cases administration of the compound as a salt may be appropriate, and pharmaceutically acceptable salts may be made by conventional methods such as those described following. Examples of suitable pharmaceutically acceptable salts are organic acid addition salts formed with acids which form a physiologically acceptable anion, for example, tosylate, methanesulphonate and α-glycerophosphate. Suitable inorganic salts may also be formed such as sulphate, nitrate, and hydrochloride.

Pharmaceutically acceptable salts may be obtained using standard procedures well known in the art, for example by reacting the compound of formula (I) (or its ester) with a suitable acid affording a physiologically acceptable anion. It is also possible to make a corresponding alkali metal (e.g. sodium, potassium, or lithium) or alkaline earth metal (e.g. calcium) salt by treating the compound of formula (I) (and in some cases the ester) with one equivalent of an alkali metal or alkaline earth metal hydroxide or alkoxide (e.g. the ethoxide or methoxide) in aqueous medium followed by conventional purification techniques. An in vivo hydrolysable ester of the compound of formula (I) is, for example, a pharmaceutically acceptable ester which is hydrolysed in the human or animal body to produce the parent acid or alcohol.

Suitable in vivo hydrolysable esters of the compound of formula (I) formed with the hydroxy group includes inorganic esters such as phosphate esters and α-acyloxyalkyl ethers. Examples of α-acyloxyalkyl ethers include acetoxymethoxy and 2,2-dimethylpropionyloxy- methoxy. Other in vivo hydrolysable ester forming groups for hydroxy include alkanoyl, benzoyl, phenylacetyl and substituted benzoyl and phenylacetyl, alkoxycarbonyl (to give alkyl carbonate esters), dialkylcarbamoyl and N-(dialkylaminoethyl)-N-alkylcarbamoyl (to give carbamates), dialkylaminoacetyl and carboxyacetyl. Examples of substituents for benzoyl include morpholino and piperazino linked from a ring nitrogen atom via a methylene group to the 3- or 4- position of the benzoyl ring.

The identification of a compound that elevates PDH activity is the subject of the present invention. These properties may be assessed, for example, using one or more of the test procedures known in the literature, for example those set out in WO 9962506; namely test (a) - In vitro elevation of PDH activity, test (b) - In vitro elevation of PDH activity in isolated primary cells and test (c) In vivo elevation of PDH activity and these tests are incorporated herein by reference.

According to a further aspect of the invention there is provided a pharmaceutical composition which comprises the compound of formula (I) as defined hereinbefore or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, in association with a pharmaceutically acceptable excipient or carrier. The composition may be in a form suitable for oral administration, for example as a tablet or capsule, for parenteral injection (including intravenous, subcutaneous, intramuscular, intravascular or infusion) for example as a sterile solution, suspension or emulsion, for topical administration for example as an ointment or cream or for rectal administration for example as a suppository. In general the above compositions may be prepared in a conventional manner using conventional excipients.

The compositions of the present invention are advantageously presented in unit dosage form. The compound will normally be administered to a warm-blooded animal at a unit dose within the range 5-5000 mg per square metre body area of the animal, i.e. approximately 0.1-100 mg/kg. A unit dose in the range, for example, 1-100 mg/kg, preferably 1-50 mg/kg is envisaged and this normally provides a therapeutically-effective dose. A unit dose form such as a tablet or capsule will usually contain, for example 1-250 mg of active ingredient.

According to a further aspect of the present invention there is provided the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined hereinbefore for use in a method of treatment of the human or animal body by therapy.

We have found that the compound of the present invention elevates PDH activity and is therefore of interest for their blood glucose-lowering effects.

A further feature of the present invention is the compound of formula (I) and pharmaceutically acceptable salts or in vivo hydrolysable esters thereof for use as a medicament.

Conveniently this is the compound of formula (I), or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, for use as a medicament for producing an elevation of PDH activity in a warm-blooded animal such as a human being.

Particularly this is the compound of formula (I), or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, for use as a medicament for treating diabetes mellitus in a warm-blooded animal such as a human being.

Particularly this is the compound of formula (I), or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, for use as a medicament for treating diabetes mellitus, peripheral vascular disease and myocardial ischaemia in a warm-blooded animal such as a human being.

Thus according to a further aspect of the invention there is provided the use of the compound of formula (I), or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof in the manufacture of a medicament for use in the production of an elevation of PDH activity in a warm-blooded animal such as a human being.

Thus according to a further aspect of the invention there is provided the use of the compound of formula (I), or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof in the manufacture of a medicament for use in the treatment of diabetes mellitus in a warm-blooded animal such as a human being.

Thus according to a further aspect of the invention there is provided the use of the compound of formula (I), or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof in the manufacture of a medicament for use in the treatment of diabetes mellitus, peripheral vascular disease and myocardial ischaemia in a warm-blooded animal such as a human being.

According to a further aspect of the invention there is provided a pharmaceutical composition which comprises the compound of formula (I) as defined hereinbefore or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, in association with a pharmaceutically acceptable excipient or carrier for use in producing an elevation of PDH activity in an warm-blooded animal, such as a human being.

According to a further aspect of the invention there is provided a pharmaceutical composition which comprises the compound of formula (I) as defined hereinbefore or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, in association with a pharmaceutically acceptable excipient or carrier for use in the treatment of diabetes mellitus in an warm-blooded animal, such as a human being.

According to a further aspect of the invention there is provided a pharmaceutical composition which comprises the compound of formula (I) as defined hereinbefore or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, in association with a pharmaceutically acceptable excipient or carrier for use in the treatment of diabetes mellitus, peripheral vascular disease and myocardial ischaemia in an warm-blooded animal, such as a human being.

According to a further feature of the invention there is provided a method for producing an elevation of PDH activity in a warm-blooded animal, such as a human being, in need of such treatment which comprises administering to said animal an effective amount of the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined hereinbefore. According to a further feature of the invention there is provided a method of treating diabetes mellitus in a warm-blooded animal, such as a human being, in need of such treatment which comprises administering to said animal an effective amount of the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined hereinbefore.

According to a further feature of the invention there is provided a method of treating diabetes mellitus, peripheral vascular disease and myocardial ischaemia in a warm-blooded animal, such as a human being, in need of such treatment which comprises administering to said animal an effective amount of the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined hereinbefore.

As stated above the size of the dose required for the therapeutic or prophylactic treatment of a particular disease state will necessarily be varied depending on the host treated, the route of administration and the severity of the illness being treated. Preferably a daily dose in the range of 1-50 mg/kg is employed. However the daily dose will necessarily be varied depending upon the host treated, the particular route of administration, and the severity of the illness being treated. Accordingly the optimum dosage may be determined by the practitioner who is treating any particular patient.

The elevation of PDH activity described herein may be applied as a sole therapy or may involve, in addition to the subject of the present invention, one or more other substances and/or treatments. Such conjoint treatment may be achieved by way of the simultaneous, sequential or separate administration of the individual components of the treatment. For example in the treatment of diabetes mellitus chemotherapy may include the following main categories of treatment: i) insulin; ii) insulin secretagogue agents designed to stimulate insulin secretion (for example glibenclamide, tolbutamide, other sulphonylureas); iii) oral hypoglycaemic agents such as metformin, thiazolidinediones; iv) agents designed to reduce the absorption of glucose from the intestine (for example acarbose); v) agents designed to treat complications of prolonged hyperglycaemia; vi) other agents used to treat lactic acidaemia; vii) inhibitors of fatty acid oxidation; viii) lipid lowering agents; ix) agents used to treat coronary heart disease and peripheral vascular disease such as aspirin, pentoxifylline, cilostazol; and/or x) thiamine.

As stated above the compound defined in the present invention is of interest for its ability to elevate the activity of PDH. The compound of the invention may therefore be useful in a range of disease states including diabetes mellitus, peripheral vascular disease, (including intermittent claudication), cardiac failure and certain cardiac myopathies, myocardial ischaemia, cerebral ischaemia and reperfusion, muscle weakness, hyperlipidaemias, Alzheimers disease and/or atherosclerosis. Alternatively such compounds of the invention may be useful in a range of disease states including peripheral vascular disease, (including intermittent claudication), cardiac failure and certain cardiac myopathies, myocardial ischaemia, cerebral ischaemia and reperfusion, muscle weakness, hyperlipidaemias, Alzheimer's disease and/or atherosclerosis in particular peripheral vascular disease and myocardial ischaemia. In addition to its use in therapeutic medicine, the compound of formula (I) and its pharmaceutically acceptable salts and in vivo hydrolysable esters are also useful as pharmacological tools in the development and standardisation of in vitro and in vivo test systems for the evaluation of the effects of elevators of PDH activity in laboratory animals such as cats, dogs, rabbits, monkeys, rats and mice, as part of the search for new therapeutic agents.

The invention will now be illustrated by the following non-limiting example in which, unless stated otherwise:

(i) temperatures are given in degrees Celsius (°C); operations were carried out at room or ambient temperature, that is, at a temperature in the range of 18-25°C and under an atmosphere of an inert gas such as argon;

(ii) organic solutions were dried over anhydrous magnesium sulphate; evaporation of solvent was carried out using a rotary evaporator under reduced pressure (600-4000 Pascals; 4.5-30 mmHg) with a bath temperature of up to 60°C; (iii) chromatography means flash chromatography on silica gel; where a silica Mega Bond Elut column is referred to, this means a column containing 50 g of silica of 40 micron particle size, the silica being contained in a 60 ml disposable syringe and supported by a porous disc, obtained from Narian, Harbor City, California, USA under the name "Mega Bond Elut SI"; "Mega Bond Elut" is a trademark; (iv) in general, the course of reactions was followed by TLC and reaction times are given for illustration only;

(v) yields are given for illustration only and are not necessarily those which can be obtained by diligent process development; preparations were repeated if more material was required; (vi) where given, NMR data is in the form of delta values for major diagnostic protons, given in parts per million (ppm) relative to tetramethylsilane (TMS) as an internal standard, determined at 300 MHz (unless otherwise stated) using perdeuterio dimethyl sulphoxide (DMSO-δ₆) as solvent;

(vii) chemical symbols have their usual meanings; SI units and symbols are used; (viii) solvent ratios are given in volume : volume (v/v) terms;

(ix) mass spectra (MS) were run with an electron energy of 70 electron volts in the chemical ionisation (CI) mode using a direct exposure probe; where indicated ionisation was effected by electron impact (El), fast atom bombardment (FAB) or electrospray (ESP); values for m/z are given; generally, only ions which indicate the parent mass are reported; (x) The following abbreviations are used:

DMF N,N-dimethylformamide;

DMSO dimethylsulphoxide;

THF tetrahydrofuran;

DCM dichloromethane; and (xi) where (R) or (S) stereochemistry is quoted at the beginning of a name, unless further clarified, it is to be understood that the indicated stereochemistry refers to the -ΝH-C(O)-C*(Me)(CF₃)(OH) centre as depicted in formula (I).

Example 1 (R)-N- \4- ( 6-Morpholinopyridazin-3 -ylsulphonyl 1 -2-chlorophenyn-2-hvdroxy-2-methyl-3 ,3,3- trifluoropropanamide.

(R)-N-[4- { 6-Morpholinopyridazin-3-ylsulphanyl } -2-chlorophenyl] -2-hydroxy-2- methyl-3,3,3-trifluoiOpropanamide (Method A; 60mg), glacial acetic acid (2ml), sulphuric acid, (98% specific gravity 1.84, 0.5ml) and hydrogen peroxide solution (100 volumes, 30% w/v, 0.5ml) were heated at 60°C for 30 minutes and allowed to cool. The reaction mixture was neutralised with saturated sodium hydrogen carbonate solution to pH8 and then extracted with ethyl acetate (2x50ml). The organic layers were combined, dried and evaporated to dryness to give the title compound as a pale yellow solid (52mg, 81%). NMR: 1.6 (s, 3H), 3.7 (s, 8H), 7.4 (d, IH), 7.9-8.0 (m, 2H), 8.05 (d, IH), 8.1 (d, IH), 8.3 (d, IH), 9.95 (s, IH); m/z 495 MH⁺.

Preparation of Starting Materials

The starting materials for the Example above are either commercially available or are readily prepared by standard methods from known materials. For example the following reactions are illustrations but not limitations of the preparation of some of the starting materials used in the above reaction.

Method A

(R)-N- f4- { 6-Morpholinopyridazin-3 -ylsulphanyl 1 -2-chlorophenyl] -2-hydroxy-2-methyl-3 ,3,3- trifluoiOpropanamide

(R)-N-(4-Thiocyanato-2-chlorophenyl)-2-trimethylsilyloxy-2-methyl-3,3,3- trifluoropropanamide (Method B, 500mg) was dissolved in DMF (5ml) and sodium sulphide (363mg) as a solution in water (5ml) was added. The mixture was heated at 50°C for 30 minutes and allowed to cool. 3-Chloro-6-morpholinopyridazine (US 4104385; 277mg) was dissolved in DMF (5ml) and added to the reaction mixture. The resulting mixture was heated at 140°C for 4 hours and allowed to cool. Ethyl acetate (25ml) was added and the organic layer was washed with brine (3x 100ml), dried and evaporated to dryness.

Tetrabutylammoniumfluoride (IM solution in THF, 1.4ml) was added to the residue dissolved in THF (5ml) and the solution was stirred for 2 hours and then evaporated to dryness. The residue was chromatographed over silica (Mega Bond Elut) eluting with ethyl acetate / hexane; 1 : 1 to yield the title compound 367mg (63%). ΝMR (400MHz) 1.6 (s, 3H), 3.50- 3.55 (m, 4H), 3.6-3.7 (m, 4H), 7.25 (d, IH), 7.35 (d, IH), 7.4 (d, IH), 7.65 (s, IH), 7.85 (s, IH), 8.05 (d, IH), 9.75 (s, IH); m/z 463 MH⁺.

Method B

(R)-N-(4-Thiocvanato-2-chlorophenyl)-2-trimethylsilyloxy-2-methyl-3,3,3- trifluoropropanamide

4-Thiocyanato-2-chloroaniline (US 4,331,817; 14.84g) as a solution in DCM (250ml) was cooled to 0°C and stirred under an argon atmosphere. Triethylamine (9.8g, 13.6ml) was added slowly and the reaction mixture was allowed to stir for 5 minutes. (S)-3,3,3-Trifluoro- 2-(trimethylsilyloxy)-2-methylpropanoyl chloride (prepared from (R)-3,3,3-trifluoro-2- hydroxy-2-methylpropionic acid (WO 9962506, 20g) as described in J. Med. Chem., 1999, 42, 2741-2746; 24g) as a solution in DCM (100ml) was added dropwise over 15minutes. The resulting mixture was allowed to warm to room temperature and stirred overnight. The reaction mixture was washed with hydrochloric acid (IM, 3x150ml) and the organic layer was dried and evaporated to dryness to give the title compound (32.51g, 84.5%). NMR: 0.0 (s, 9H), 1.4 (s, 3H), 7.4 (dd, IH), 7.65 (d, IH), 7.8 (d, IH), 9.3 (s, IH); m/z 397 MH⁺.

Example 2

The following illustrate representative pharmaceutical dosage forms containing the compound of formula (I), or a pharmaceutically acceptable salt or in vivo hydrolysable ester thereof (hereafter compound X), for therapeutic or prophylactic use in humans :-

Note

The above formulations may be obtained by conventional procedures well known in the pharmaceutical art. The tablets (a)-(c) may be enteric coated by conventional means, for example to provide a coating of cellulose acetate phthalate.

Claims

The compound of formula (I):

(I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof.

2. A process for preparing the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof, which process (in which variable groups are as defined for formula (I) unless otherwise stated) comprises of: (a) deprotecting a protected compound of formula (II):

(HI)

(c) coupling the compound of formula (IV):

(IN) with an acid of formula (N):

wherein X is OH;

(d) coupling an aniline of formula (IN) with an activated acid derivative of formula (N); and thereafter if necessary: i) separating a mixture of enantiomers to give the (R)-enantiomer; ii) removing any protecting groups; or iii) forming a pharmaceutically acceptable salt or in vivo hydrolysable ester.

3. A pharmaceutical composition which comprises the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined in claim 1, in association with a pharmaceutically acceptable excipient or carrier.

4. The compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined in claim 1, for use as a medicament.

5. The use of the compound of formula (I), or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined in claim 1, in the manufacture of a medicament for use in the production of an elevation of PDH activity in a warm-blooded animal such as a human being.

6. The use of the compound of formula (I), or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined in claim 1, in the manufacture of a medicament for use in the treatment of diabetes mellitus in a warm-blooded animal such as a human being.

5 7. A method for producing an elevation of PDH activity in a warm-blooded animal, in need of such treatment which comprises administering to said animal an effective amount of the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined in claim 1.

10 8. A method of treating diabetes mellitus in a warm-blooded animal, such as a human being, in need of such treatment which comprises administering to said animal an effective amount of the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined in claim 1.

15 9. A pharmaceutical composition which comprises the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined in claim 1, in association with a pharmaceutically acceptable excipient or carrier for use in producing an elevation of PDH activity in an warm-blooded animal, such as a human being.

20 10. A pharmaceutical composition which comprises the compound of formula (I) or a pharmaceutically acceptable salt or an in vivo hydrolysable ester thereof as defined in claim 1, in association with a pharmaceutically acceptable excipient or carrier for use in the treatment of diabetes mellitus in an warm-blooded animal, such as a human being.