Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D403/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00
  • C07D403/14—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing three or more hetero rings
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/33—Heterocyclic compounds
  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/495—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with two or more nitrogen atoms as the only ring heteroatoms, e.g. piperazine or tetrazines
  • A61K31/505—Pyrimidines; Hydrogenated pyrimidines, e.g. trimethoprim
  • A61K31/506—Pyrimidines; Hydrogenated pyrimidines, e.g. trimethoprim not condensed and containing further heterocyclic rings
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P1/00—Drugs for disorders of the alimentary tract or the digestive system
  • A61P1/04—Drugs for disorders of the alimentary tract or the digestive system for ulcers, gastritis or reflux esophagitis, e.g. antacids, inhibitors of acid secretion, mucosal protectants
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P11/00—Drugs for disorders of the respiratory system
  • A61P11/06—Antiasthmatics
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P17/00—Drugs for dermatological disorders
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P17/00—Drugs for dermatological disorders
  • A61P17/04—Antipruritics
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P19/00—Drugs for skeletal disorders
  • A61P19/02—Drugs for skeletal disorders for joint disorders, e.g. arthritis, arthrosis
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P29/00—Non-central analgesic, antipyretic or antiinflammatory agents, e.g. antirheumatic agents; Non-steroidal antiinflammatory drugs [NSAID]
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
  • C07D401/14—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing three or more hetero rings

Definitions

• H4 Antagonist Compounds This application relates to novel compounds and their use as Histamine H4 receptor antagonists. Compounds described herein may be useful in the treatment or prevention of diseases in which H4 receptors are involved. The application is also directed to pharmaceutical compositions comprising these compounds and the manufacture and use of these compounds and compositions in the prevention or treatment of such diseases in which H4 receptors are involved. BACKGROUND OF THE INVENTION Histamine is a short-acting biogenic amine generated in mast cells where it is stored in cytosolic granules and released in response to various immunological and non- immunological stimuli.
• Histamine release from mast cells has been traditionally associated with mild to severe signs and symptoms that characterize hypersensitivity reactions, including erythema, urticaria, itching, tachycardia, hypotension, ventricular fibrillations, bronchospasm, and cardiac and respiratory arrest. To date, numerous additional sources have been identified, including basophils, neurons and cancer cells. In addition to modulating a wide range of physiological processes, histamine is implicated in pathological conditions including allergies and anaphylaxis, asthma and chronic inflammation, autoimmune, cardiovascular, neuropsychiatric and endocrine disorders as well as cancer.
• H1–H4 G- protein-coupled receptors
• the H2 receptor is responsible for gastric acid secretion; the H3 receptor controls the release of histamine and other neuromodulators in the CNS and the H1 receptor is associated with wakefulness and inflammatory response.
• the high affinity H4 receptor displays constitutive activity and is expressed mostly, but not exclusively on cells of the immune system including mast cells, monocytes, dendritic cells, eosinophils, basophils, neutrophils, and T cells.
• H4R shares only 40% homology with its nearest neighbour the H3R and neither H2 nor H1 antagonists were shown to inhibit histamine induced eosinophil chemotaxis. Histamine has been shown to inhibit forskolin-induced cAMP responses in a pertussis toxin (PTx)-sensitive manner, suggesting that H4R signals via heterotrimeric G ⁇ i/o proteins.
• Transient expression of the H4R in heterologous cell systems e.g. HEK293 cells
• HEK293 cells is a widely used method to measure H4 ligand signaling and binding to generate estimates of functional potency and receptor affinity respectively.
• H4R antagonists using these techniques and their study in various animal disease models including asthma, chronic pruritus, dermatitis, rheumatoid arthritis, gastric ulcerogenesis and colitis has confirmed H4R antagonism leads to a profound anti-inflammatory effect and has validated the therapeutic benefit for targeting this receptor.
• the first H4R antagonist phase 2a clinical trial in patients suffering from moderate-to-severe atopic dermatitis has already been conducted, further confirming H4 as a druggable target in patients Notwithstanding a number of published H4R ligands, there remains a need to develop new H4R antagonists with good drug candidate quality.
• These antagonists should display excellent low nM potency and affinity with full selectivity against H1- H3 receptors.
• hERG human ether-a-go-go-related gene
• IKr delayed rectifier potassium channel
• the channels ability to conduct electrical current across the cell membrane is inhibited or compromised by application of drugs, it can result in a potentially fatal disorder called QT syndrome.
• QT syndrome a potentially fatal disorder
• a number of clinically successful drugs in the market have had the tendency to inhibit hERG, and create a concomitant risk of sudden death, as a side- effect, which has made hERG inhibition an important anti- target that must be avoided during drug development.
• Compounds of the invention are antagonists of the H4 receptor. Certain compounds have a low hERG inhibition, making these particularly beneficial.
• THE INVENTION The present invention provides compounds having activity as H4 receptor antagonists. More particularly, the invention provides compounds that combine H4 receptor antagonism with low hERG activity.
• the invention provides a compound of the formula (1): or a salt thereof, wherein; X is CH or N; n is 1 or 2; R 1 is selected from H or C 1-3 alkyl; R 2 is H; and A represents an optionally substituted pyrazole ring; wherein the compound is selected from the group consisting of:
• the compounds may be used as H4 receptor antagonists.
• the compounds may be used in the manufacture of medicaments.
• the compounds or medicaments may be for use in treating, preventing, ameliorating, controlling or reducing the risk of inflammatory disorders including asthma, chronic pruritus, dermatitis, rheumatoid arthritis, gastric ulcerogenesis and colitis.
• DETAILED DESCRIPTION OF THE INVENTION The invention relates to novel compounds.
• the invention also relates to the use of novel compounds as antagonists of the H4 receptor.
• the invention further relates to the use of novel compounds in the manufacture of medicaments for use as H4 receptor antagonists or for the treatment of H4 system dysfunction.
• the invention further relates to compounds, compositions and medicaments which are selective H4 receptor antagonists.
• the invention further relates to compounds, compositions and medicaments useful for the treatment of acute and chronic inflammation, autoimmune disease, host defense disorders and neuropathic pain.
• the invention further relates to compounds, compositions and medicaments useful for the treatment of inflammatory disorders including asthma, chronic pruritus, dermatitis, rheumatoid arthritis, gastric ulcerogenesis and colitis.
• Compounds of the invention include compounds of the formula (1): or a salt thereof, wherein; X is CH or N; n is 1 or 2; R 1 is selected from H or C 1-3 alkyl; R 2 is H; and A represents an optionally substituted pyrazole ring; wherein the compound is selected from the group consisting of:
• Compounds of the invention include compounds of the formula (1a): or a salt thereof, wherein; n is 1 or 2; R 1 is selected from H or C 1-3 alkyl; R 2 is H; and A represents an optionally substituted pyrazole ring; wherein the compound is selected from the group consisting of:
• the compound can be selected from the group consisting of: 4-(1-(Difluoromethyl)-1H-pyrazol-4-yl)-6-(3-(methylamino)azetidin-1-yl)pyrimidin-2- amine; 4-(3-(Methylamino)azetidin-1-yl)-6-(1-(2,2,2-trifluoroethyl)-1H-pyrazol-4-yl)pyrimidin-2- amine; 4-(1-Ethyl-1H-pyrazol-4-yl)-6-(3-(methylamino)azetidin-1-yl)pyrimidin-2-amine; 4-(1-(Difluoromethyl)-3-methyl-1H-pyrazol-4-yl)-6-(3-(methylamino)azetidin-1- yl)pyrimidin-2-amine; (R)-4-(5-Chloro-1-methyl-1H-pyrazol-4-yl)-6-(3
• the compound can be a compound selected from the group consisting of: or a salt thereof.
• Specific examples of compounds include those having low hERG activity.
• the compounds of the invention exhibit low hERG activity which is particularly beneficial for the reasons outlined in the background section above.
• Compounds exhibiting low hERG activity herein in particular are those with a hERG pIC 50 of 4.5 and below. Definitions In this application, the following definitions apply, unless indicated otherwise.
• treatment in relation to the uses of any of the compounds described herein, is used to describe any form of intervention where a compound is administered to a subject suffering from, or at risk of suffering from, or potentially at risk of suffering from the disease or disorder in question.
• the term “treatment” covers both preventative (prophylactic) treatment and treatment where measurable or detectable symptoms of the disease or disorder are being displayed.
• the term “effective therapeutic amount” as used herein refers to an amount of the compound which is effective to produce a desired therapeutic effect. For example, if the condition is pain, then the effective therapeutic amount is an amount sufficient to provide a desired level of pain relief.
• the desired level of pain relief may be, for example, complete removal of the pain or a reduction in the severity of the pain.
• the present invention extends to all optical isomers of such compounds, whether in the form of racemates or resolved enantiomers.
• the invention described herein relates to all crystal forms, solvates and hydrates of any of the disclosed compounds however so prepared.
• any of the compounds disclosed herein have acid or basic centres such as carboxylates or amino groups, then all salt forms of said compounds are included herein.
• the salt should be seen as being a pharmaceutically acceptable salt.
• Salts or pharmaceutically acceptable salts that may be mentioned include acid addition salts and base addition salts.
• Such salts may be formed by conventional means, for example by reaction of a free acid or a free base form of a compound with one or more equivalents of an appropriate acid or base, optionally in a solvent, or in a medium in which the salt is insoluble, followed by removal of said solvent, or said medium, using standard techniques (e.g.
• Salts may also be prepared by exchanging a counter-ion of a compound in the form of a salt with another counter-ion, for example using a suitable ion exchange resin.
• suitable ion exchange resin examples include acid addition salts derived from mineral acids and organic acids, and salts derived from metals such as sodium, magnesium, potassium and calcium.
• acid addition salts include acid addition salts formed with acetic, 2,2- dichloroacetic, adipic, alginic, aryl sulfonic acids (e.g.
• D-gluconic D-glucuronic
• glutamic e.g. L-glutamic
• ⁇ - oxoglutaric glycolic, hippuric, hydrobromic, hydrochloric, hydriodic, isethionic
• lactic e.g. (+)-L-lactic and ( ⁇ )-DL-lactic
• lactobionic maleic, malic (e.g.
• Preferred solvates are solvates formed by the incorporation into the solid state structure (e.g. crystal structure) of the compounds of the invention of molecules of a non-toxic pharmaceutically acceptable solvent (referred to below as the solvating solvent).
• a non-toxic pharmaceutically acceptable solvent referred to below as the solvating solvent.
• solvents include water, alcohols (such as ethanol, isopropanol and butanol) and dimethylsulfoxide.
• Solvates can be prepared by recrystallising the compounds of the invention with a solvent or mixture of solvents containing the solvating solvent. Whether or not a solvate has been formed in any given instance can be determined by subjecting crystals of the compound to analysis using well known and standard techniques such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray crystallography.
• TGA thermogravimetric analysis
• DSC differential scanning calorimetry
• X-ray crystallography X-ray crystallography
• the solvates can be stoichiometric or non-stoichiometric solvates.
• Particular solvates may be hydrates, and examples of hydrates include hemihydrates, monohydrates and dihydrates
• solvates and the methods used to make and characterise them see Bryn et al, Solid-State Chemistry of Drugs, Second Edition, published by SSCI, Inc of West Lafayette, IN, USA, 1999, ISBN 0-967- 06710-3.
• pharmaceutical composition in the context of this invention means a composition comprising an active agent and comprising additionally one or more pharmaceutically acceptable carriers.
• composition may further contain ingredients selected from, for example, diluents, adjuvants, excipients, vehicles, preserving agents, fillers, disintegrating agents, wetting agents, emulsifying agents, suspending agents, sweetening agents, flavouring agents, perfuming agents, antibacterial agents, antifungal agents, lubricating agents and dispersing agents, depending on the nature of the mode of administration and dosage forms.
• ingredients selected from, for example, diluents, adjuvants, excipients, vehicles, preserving agents, fillers, disintegrating agents, wetting agents, emulsifying agents, suspending agents, sweetening agents, flavouring agents, perfuming agents, antibacterial agents, antifungal agents, lubricating agents and dispersing agents, depending on the nature of the mode of administration and dosage forms.
• compositions may take the form, for example, of tablets, dragees, powders, elixirs, syrups, liquid preparations including suspensions, sprays, inhalants, tablets, lozenges, emulsions, solutions, cachets, granules, capsules and suppositories, as well as liquid preparations for injections, including liposome preparations.
• the compounds of the invention may contain one or more isotopic substitutions, and a reference to a particular element includes within its scope all isotopes of the element.
• a reference to hydrogen includes within its scope 1 H, 2 H (D), and 3 H (T).
• references to carbon and oxygen include within their scope respectively 12 C, 13 C and 14 C and 16 O and 18 O.
• a reference to a particular functional group also includes within its scope isotopic variations, unless the context indicates otherwise.
• a reference to an alkyl group such as an ethyl group or an alkoxy group such as a methoxy group also covers variations in which one or more of the hydrogen atoms in the group is in the form of a deuterium or tritium isotope, e.g. as in an ethyl group in which all five hydrogen atoms are in the deuterium isotopic form (a perdeuteroethyl group) or a methoxy group in which all three hydrogen atoms are in the deuterium isotopic form (a trideuteromethoxy group).
• the isotopes may be radioactive or non-radioactive.
• Therapeutic dosages may be varied depending upon the requirements of the patient, the severity of the condition being treated, and the compound being employed. Determination of the proper dosage for a particular situation is within the skill of the art. Generally, treatment is initiated with the smaller dosages which are less than the optimum dose of the compound. Thereafter the dosage is increased by small increments until the optimum effect under the circumstances is reached. For convenience, the total daily dosage may be divided and administered in portions during the day if desired. The magnitude of an effective dose of a compound will, of course, vary with the nature of the severity of the condition to be treated and with the particular compound and its route of administration.
• the daily dose range may be from about 10 ⁇ g to about 30 mg per kg body weight of a human and non-human animal, preferably from about 50 ⁇ g to about 30 mg per kg of body weight of a human and non-human animal, for example from about 50 ⁇ g to about 10 mg per kg of body weight of a human and non-human animal, for example from about 100 ⁇ g to about 30 mg per kg of body weight of a human and non-human animal, for example from about 100 ⁇ g to about 10 mg per kg of body weight of a human and non-human animal and most preferably from about 100 ⁇ g to about 1 mg per kg of body weight of a human and non-human animal.
• Methods for the Preparation of Compounds of the Invention Provided is a process for the preparation of a compound as defined above comprising: (A) the reaction of a compound of the formula (10): with a compound of the formula (11): under SNAr conditions or transition metal catalyzed coupling conditions; wherein A is an optionally substituted pyrazole ring; R 1 is H, methyl or ethyl; R 2 is H; X is N or CH; n is 1 or 2; and LG represents a suitable leaving group; or (B) the reaction of a compound of the formula (12): with a compound of the formula (13): under transition metal catalyzed coupling conditions or under SNAr conditions; wherein A, R 1 , R 2 , X and n are as defined above, LG represents a suitable leaving group and M, which may be present or absent, represents a suitably substituted metal or non-metal; or In process variant (A), the compound of formula (10) may be reacted with the compound of formula
• the SNAr reaction is typically carried out using either an excess of the compound of formula (11), or a stoichiometric quantity of the compound of formula (11) in the presence of a base which may be a tertiary amine base such as TEA or DIPEA or an inorganic base such as K 2 CO 3 , Cs 2 CO 3 or NaHCO 3 , optionally in a suitable solvent such as H 2 O, MeCN, 1,4-dioxane, THF, MeOH, EtOH, IPA, BuOH, DMF, NMP or DMSO, or a combination of suitable solvents, at a temperature between about room temperature to about 200 °C, using conventional heating or optionally by heating with microwave irradiation, in an open vessel or optionally in a sealed vessel, optionally at a pressure greater than atmospheric pressure, optionally in the presence of an additive such as KF or a silver salt.
• a base which may be a tertiary amine base such as TEA or DIPEA
• the compound of formula (11) may be present in the reaction as an acid salt such as an HCl, HBr or a TFA salt optionally in the presence of a tertiary base such as TEA or DIPEA.
• the leaving group LG in the compound of formula (10) may be a halogen such as F, Cl or Br; an alkoxy group such as OMe; an aryloxy group such as pentafluorophenoxy; a sulfenyl group such as SMe, a sulfinyl group such as SOMe, a sulfonyl group such as SO 2 Me, a sulfonyloxy group such as OTs, OMs, ONs or OTf; or a leaving group generated by reaction of a hydroxy group with a peptide coupling reagent such as BOP, PyBOP or HATU.
• the compound of formula (10) may be reacted with the compound of formula (11) under transition metal catalyzed coupling conditions.
• the transition metal catalyzed coupling reaction is typically carried out using the compound of formula (11) in the presence of an inorganic base such as NaO t Bu, KO t Bu, K 3 PO 4 , K 2 CO 3 or Cs 2 CO 3 , in a suitable solvent such as 1,4-dioxane, THF, DME or toluene, or a combination of suitable solvents, in the presence of a sub-stoichiometric quantity of a transition metal catalyst such as Pd(OAc) 2 , Pd 2 (dba) 3 , Pd(dppf)Cl 2 , Pd(PPh 3 ) 2 Cl 2 or Pd(PPh 3 ) 4 , optionally in the presence of a sub-stoichiometric quantity of a phosphine ligand such as PPh 3 , P
• the leaving group LG in the compound of formula (10) may be a halogen such as Cl, Br or I, or a sulfonyloxy group such as OTs, OMs, ONs or OTf.
• Compounds of formula (10) can be prepared by the reaction shown in Scheme 1 below:
• a compound of formula (14), wherein X is as defined above, and LG and LG 1 may be the same or different and represent suitable leaving groups may be reacted with a compound of formula (13) wherein A is as defined in above and M which may be present or absent, represents a suitably substituted metal or non-metal, under transition metal catalyzed coupling conditions or under SNAr conditions to form a compound of formula (10).
• transition metal catalyzed coupling reaction or the SNAr reaction is typically carried as described below in process variant (B), and the compounds of formula (13) and formula (14) may be commercially available or easily prepared by standard methods reported in the published literature from simple starting materials known to the skilled person. Occasionally, due to their instability, it may be necessary to generate compounds of formula (13), where M is present, in- situ at low temperatures, e.g. between about -78 °C and room temperature, and react them further in a transition metal catalyzed coupling reaction, without their prior isolation. Details of such methods are known in the published literature, e.g. as reported by Oberli and Buchwald in Org. Lett., 2012, Vol.14, No.17, p 4606.
• a carboxylic acid of formula (15) may be homologated to the corresponding beta-keto ester (16) by first activating it via a number of standard methods known to the skilled person, e.g. by reaction with CDI in a suitable solvent such as MeCN, and then reacting with a malonic acid derivative such as potassium 3-ethoxy-3- oxopropanoate in the presence of a Lewis acid such as MgCl 2 .
• the beta-keto ester (16) may be cyclised to the amino-hydroxypyrimidine analogue (17) by reaction with guanidine or an appropriate guanidine salt in the presence of a suitable base such as KO t Bu in a suitable solvent such as MeOH.
• a suitable base such as KO t Bu
• a suitable solvent such as MeOH.
• the amino- hydroxypyrimidine analogue (17) so formed may then be reacted with POCl 3 in the presence or absence of a suitable solvent to form a compound of formula (18).
• Compounds of formula (15) may be commercially available or easily prepared by standard methods reported in the published literature from simple starting materials known to the skilled person.
• Compounds of formula (11) may be commercially available or easily prepared by standard methods reported in the published literature from simple starting materials known to the skilled person.
• the compound of formula (12) may be reacted with the compound of formula (13) under transition metal catalyzed coupling conditions.
• the transition metal catalyzed coupling reaction is typically carried out using the compound of formula (13) wherein M is present.
• the transition metal catalyzed coupling reaction is typically carried out in the presence of an inorganic base such as NaHCO 3 , Na 2 CO 3 , K 2 CO 3 , Cs 2 CO 3 or K 3 PO 4 , in a suitable solvent such as H 2 O, MeCN, 1,4-dioxane, THF, Et 2 O, DME, EtOH, IPA, DMF, NMP or toluene, or a combination of suitable solvents, in the presence of a sub-stoichiometric quantity of a transition metal catalyst such as Pd(OAc) 2 , Pd 2 (dba) 3 , Pd(dppf)Cl 2 , Pd(PP
• the leaving group LG in the compound of formula (12) may be a halogen such as Cl, Br or I, or a sulfonyloxy group such as OTs, OMs or OTf.
• M represents a trifluoroborate salt BF 3 -
• the transition metal catalyzed coupling reaction is typically carried out in the presence of an inorganic base such as Na 2 CO 3 , K 2 CO 3 , Cs 2 CO 3 or K 3 PO 4 , in a suitable solvent such as H 2 O, MeCN 14-dioxane THF MeOH or EtOH or a combination of suitable solvents in the presence of a sub-stoichiometric quantity of a transition metal catalyst such as Pd(OAc) 2 , Pd 2 (dba) 3 , optionally in the presence of a sub-stoichiometric quantity of a phosphine ligand such as PPh 3 , PCy 3 or RuPhos at a temperature between about room temperature to
• the leaving group LG in the compound of formula (12) may be a halogen such as Cl, Br or I.
• M represents a trialkyltin group such as SnMe 3 or SnBu 3
• the transition metal catalyzed coupling reaction is typically carried out in a suitable solvent such 1,4-dioxane, THF, DMF, or toluene, or a combination of suitable solvents, in the presence of a sub-stoichiometric quantity of a transition metal catalyst such as Pd(OAc) 2 , Pd 2 (dba) 3 , Pd(PPh 3 ) 2 Cl 2 or Pd(PPh 3 ) 4 , optionally in the presence of an inorganic base such as K 2 CO 3 or CsF, optionally in the presence of an additive such as LiCl, CuI, Bu 4 NBr or Et 4 NCl, at a temperature between about room temperature to about 200 °C, using conventional heating or optionally by heating with microwave irradiation,
• the leaving group LG in the compound of formula (12) may be a halogen such as Cl, Br or I.
• the transition metal catalyzed coupling reaction is typically carried out in the presence of an inorganic base such as NaOtBu, KOtBu, K 3 PO 4 , K 2 CO 3 or Cs 2 CO 3 , in a suitable solvent such as 1,4-dioxane, THF, DME or toluene, or a combination of suitable solvents, in the presence of a sub- stoichiometric quantity of a transition metal catalyst such as Pd(OAc) 2 , Pd 2 (dba) 3 , Pd(dppf)Cl 2 , Pd(PPh 3 ) 2 Cl 2 or Pd(PPh 3 ) 4 , optionally in the presence of a sub- stoichiometric quantity of a phosphine ligand such as PPh 3 , PBu 3 , PtBu 3 ,
• the leaving group LG in the compound of formula (12) may be a halogen such as Cl, Br or I, or a sulfonyloxy group such as OTs, OMs, ONs or OTf.
• M when M is absent, then the transition metal catalyzed coupling reaction is typically carried out in the presence of an inorganic base such as K3PO4, K 2 CO3 or Cs 2 CO 3 , in a suitable solvent such as 1,4-dioxane, DMF, DMSO or toluene, or a combination of suitable solvents, in the presence of a sub-stoichiometric quantity of a transition metal catalyst such as CuI, optionally in the presence of a sub- stoichiometric quantity of an amine such as (S)-proline or trans-N 1 ,N 2 - dimethylcyclohexane-1,2-diamine at a temperature between about room temperature to about 200 °C, using conventional heating or optionally by heating with microwave ir
• the leaving group LG in the compound of formula (12) may be a halogen such as Cl, Br or I.
• the transition metal catalyzed coupling reaction is typically carried out in the presence of an organic base such as nBu4OAc, in a suitable solvent such as 1,4-dioxane, in the presence of a sub-stoichiometric quantity of a transition metal pre-catalyst such as XPhos Pd G2, optionally in the presence of a sub-stoichiometric quantity of a phosphine ligand such as XPhos, at a temperature between about room temperature to about 200 °C, using conventional heating or optionally by heating with microwave irradiation, in an open vessel or optionally in a sealed vessel, optionally at a pressure greater than atmospheric pressure.
• the leaving group LG in the compound of formula (12) may be a halogen such as Cl.
• the compound of formula (12) may be reacted with the compound of formula (13) under SNAr conditions.
• the SNAr reaction is typically carried out using the compound of formula (13) wherein M is absent, in the presence of a tertiary amine base such as TEA or DIPEA or an inorganic base such as K 2 CO 3 , Cs 2 CO 3 , KOtBu, or NaH in a suitable solvent such as THF, DMF, H2O, DMSO or NMP, or a combination of suitable solvents, at a temperature between about room temperature to about 200 °C, using conventional heating or optionally by heating with microwave irradiation, in an open vessel or optionally in a sealed vessel, optionally at a pressure greater than atmospheric pressure.
• a tertiary amine base such as TEA or DIPEA
• an inorganic base such as K 2 CO 3 , Cs 2 CO 3
• the leaving group LG in the compound of formula (12) may be a halogen such as F, Cl or Br; an alkoxy group such as OMe; an aryloxy group such as pentafluorophenoxy; a sulfenyl group such as SMe, a sulfinyl group such as SOMe, a sulfonyl group such as SO 2 Me, or a sulfonyloxy group such as OTs, OMs, ONs or OTf.
• a halogen such as F, Cl or Br
• an alkoxy group such as OMe
• an aryloxy group such as pentafluorophenoxy
• a sulfenyl group such as SMe
• a sulfinyl group such as SOMe
• SO 2 Me a sulfonyloxy group
• OTs OTs, OMs, ONs or OTf.
• the compound of formula (12) can be prepared by the sequence of reactions shown in Scheme 3 below:
• a compound of formula (14), wherein X is as defined above, and LG and LG 1 may be the same or different and represent suitable leaving groups may be reacted with a compound of formula (11), wherein R 1 , R 2 and n are as defined above, under SNAr conditions or under transition metal catalyzed coupling conditions to form a compound of formula (12).
• the SNAr reaction or the transition metal catalyzed coupling reaction is typically carried as described above in process variant (A). In many of the reactions described above, it may be necessary to protect one or more groups to prevent reaction from taking place at an undesirable location on the molecule.
• a useful protecting group for manipulating compounds of formula (10) or formula (12) includes the 2,5-dimethyl-1H-pyrrole group; useful protecting groups for manipulating compounds of formula (11) or formula (12) include BOC and CBZ; and useful protecting groups for manipulating compounds of formula (13) include SEM and THP.
• compositions comprising at least one compound of the invention as defined above together with at least one pharmaceutically acceptable excipient.
• the composition may be a tablet composition.
• the composition may be a capsule composition.
• the pharmaceutically acceptable excipient(s) can be selected from, for example, carriers (e.g.
• a solid, liquid or semi-solid carrier e.g solid diluents such as fillers or bulking agents; and liquid diluents such as solvents and co- solvents
• diluents e.g solid diluents such as fillers or bulking agents; and liquid diluents such as solvents and co- solvents
• granulating agents binders, flow aids, coating agents, release-controlling agents (e.g. release retarding or delaying polymers or waxes), binding agents, disintegrants, buffering agents, lubricants, preservatives, anti-fungal and antibacterial agents, antioxidants, buffering agents, tonicity-adjusting agents, thickening agents, flavouring agents, sweeteners, pigments, plasticizers, taste masking agents, stabilisers or any other excipients conventionally used in pharmaceutical compositions.
• diluents e.g solid diluents such as fillers or bulking agents; and liquid dilu
• pharmaceutically acceptable means compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of a subject (e.g. a human subject) without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio. Each excipient must also be “acceptable” in the sense of being compatible with the other ingredients of the formulation.
• Pharmaceutical compositions containing compounds of invention can be formulated in accordance with known techniques, see for example, Remington’s Pharmaceutical Sciences, Mack Publishing Company, Easton, PA, USA.
• compositions can be in any form suitable for oral, parenteral, topical, intranasal, intrabronchial, sublingual, ophthalmic, otic, rectal, intra-vaginal, or transdermal administration.
• Pharmaceutical dosage forms suitable for oral administration include tablets (coated or uncoated), capsules (hard or soft shell), caplets, pills, lozenges, syrups, solutions, powders, granules, elixirs and suspensions, sublingual tablets, wafers or patches such as buccal patches.
• Tablet compositions can contain a unit dosage of active compound together with an inert diluent or carrier such as a sugar or sugar alcohol, eg; lactose, sucrose, sorbitol or mannitol; and/or a non-sugar derived diluent such as sodium carbonate, calcium phosphate, calcium carbonate, or a cellulose or derivative thereof such as microcrystalline cellulose (MCC), methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, and starches such as corn starch.
• Tablets may also contain such standard ingredients as binding and granulating agents such as polyvinylpyrrolidone, disintegrants (e.g.
• swellable crosslinked polymers such as crosslinked carboxymethylcellulose
• lubricating agents e.g. stearates
• preservatives e.g. parabens
• antioxidants e.g. BHT
• buffering agents for example phosphate or citrate buffers
• effervescent agents such as citrate/bicarbonate mixtures.
• excipients are well known and do not need to be discussed in detail here. Tablets may be designed to release the drug either upon contact with stomach fluids (immediate release tablets) or to release in a controlled manner (controlled release tablets) over a prolonged period of time or with a specific region of the GI tract.
• the pharmaceutical compositions typically comprise from approximately 1% (w/w) to approximately 95%, preferably% (w/w) active ingredient and from 99% (w/w) to 5% (w/w) of a pharmaceutically acceptable excipient (for example as defined above) or combination of such excipients.
• a pharmaceutically acceptable excipient for example as defined above
• the compositions comprise from approximately 20% (w/w) to approximately 90% (w/w) active ingredient and from 80% (w/w) to 10% of a pharmaceutically excipient or combination of excipients.
• the pharmaceutical compositions comprise from approximately 1% to approximately 95%, preferably from approximately 20% to approximately 90%, active ingredient.
• compositions according to the invention may be, for example, in unit dose form, such as in the form of ampoules, vials, suppositories, pre-filled syringes, dragées, powders, tablets or capsules.
• Tablets and capsules may contain, for example, 0-20% disintegrants, 0-5% lubricants, 0-5% flow aids and/or 0-99% (w/w) fillers/ or bulking agents (depending on drug dose). They may also contain 0-10% (w/w) polymer binders, 0-5% (w/w) antioxidants, 0-5% (w/w) pigments.
• Slow release tablets would in addition typically contain 0-99% (w/w) release-controlling (e.g.
• the film coats of the tablet or capsule typically contain 0-10% (w/w) polymers, 0-3% (w/w) pigments, and/or 0-2% (w/w) plasticizers.
• Parenteral formulations typically contain 0-20% (w/w) buffers, 0-50% (w/w) cosolvents, and/or 0-99% (w/w) Water for Injection (WFI) (depending on dose and if freeze dried).
• WFI Water for Injection
• Formulations for intramuscular depots may also contain 0-99% (w/w) oils.
• the pharmaceutical formulations may be presented to a patient in “patient packs” containing an entire course of treatment in a single package, usually a blister pack.
• a formulation may contain from 1 nanogram to 2 grams of active ingredient, e.g. from 1 nanogram to 2 milligrams of active ingredient. Within these ranges, particular sub-ranges of compound are 0.1 milligrams to 2 grams of active ingredient (more usually from 10 milligrams to 1 gram eg 50 milligrams to 500 milligrams), or 1 microgram to 20 milligrams (for example 1 microgram to 10 milligrams, e.g.0.1 milligrams to 2 milligrams of active ingredient).
• a unit dosage form may contain from 1 milligram to 2 grams, more typically 10 milligrams to 1 gram, for example 50 milligrams to 1 gram, e.g.100 milligrams to 1 gram, of active compound.
• the active compound will be administered to a patient in need thereof (for example a human or animal patient) in an amount sufficient to achieve the desired therapeutic effect (effective amount).
• the precise amounts of compound administered may be determined by a supervising physician in accordance with standard procedures.
• EXAMPLES 1 TO 42 The compounds of Examples 1 to 42 shown in Table 1 below have been prepared. Their NMR and LCMS properties and the methods used to prepare them are set out in Table 3.
• Chromatography refers to column chromatography performed using 60 – 120 mesh silica gel and executed under nitrogen pressure (flash chromatography) conditions.
• Column chromatography performed using ‘basic silica’ refers to the use of Biotage® KP-NH silica gel.
• Column chromatography performed under reversed phase conditions using ‘C18 silica’ refers to the use of Biotage® KP-C18 silica gel.
• TLC for monitoring reactions refers to TLC run using the specified mobile phase and the Silica gel F254 as a stationary phase from Merck. Microwave-mediated reactions were performed in Biotage Initiator or CEM Discover microwave reactors.
• LCMS Analysis was performed under electrospray conditions using the instruments and methods given in the tables below: LCMS data in the experimental section and Tables 2 and 3 are given in the format: (Instrument system, Method): Mass ion, retention time, UV detection wavelength.
• Compound Purification Final purification of compounds was performed by preparative reversed phase HPLC using the instrument and methods detailed below where data is given in the following format: Purification technique: [phase (column description, column length ⁇ internal diameter, particle size), solvent flow- rate, gradient - given as % of mobile phase B in mobile phase A (over time), mobile phase (A), mobile phase (B)].
• Preparative HPLC purification Shimadzu LC-20AP binary system with SPD-20A UV detector Gilson semi preparative HPLC system with 321 pump, GX-271 liquid handler and Gilson 171 DAD controlled with Gilson Trilution software Purification Method A
• Prep HPLC [Reversed Phase (Sunfire C-18, 250 ⁇ 19 mm, 5 ⁇ m), 12 mL / min, gradient 0% – 30% (over 17 min), 100 % (over 1 min), 100% – 0% (over 4 min), mobile phase (A): 0.1% trifluoroacetic acid in water, (B): 100% acetonitrile].
• CDI carbonyldiimidazole
• DAST diethylaminosulfur trifluoride
• DCM dichloromethane
• DIPEA N,N-diisopropylethylamine
• ESI electro spray ionisation
• EtOAc ethyl acetate
• h hour(s)
• H 2 O water
• HCl hydrogen chloride
• HPLC high performance liquid chromatography
• IPA propan-2-ol
• LC liquid chromatography
• MeCN acetonitrile
• MS mass spectrometry
• nm nanometre(s)
• NMR nuclear magnetic resonance
• Example 1 (245 mg, 82.0%) as a white solid.
• the data for Example 1 are in Table 3.
• Example 4 and Example 16 are in Table 3.
• Route C Typical procedure for the preparation of pyrimidines as exemplified by the preparation of Example 5, (R)-4-(5-chloro-1-methyl-1H-pyrazol-4-yl)-6-(3-(methylamino)pyrrolidin-1- yl)pyrimidin-2-amine
• Example 5 (35 mg, 20%) as a white solid.
• the data for Example 5 are in Table 3.
• Route D Typical procedure for the preparation of pyrimidines as exemplified by the preparation of Example 19, 4-(3-methyl-1-(2,2,2-trifluoroethyl)-1H-pyrazol-4-yl)-6-(3-(methylamino)azetidin-1- yl)pyrimidin-2-amine 3-Methyl-1-(2,2,2-trifluoroethyl)-1H-pyrazole-4-carboxylic acid Intermediate 27 (1.0 g, 4.8 mmol) was dissolved in dry THF (100 mL) under N2 gas and solution was cooled to 0°C.
• Example 19 (27 mg, 33%) as a white solid.
• the data for Example 19 are in Table 3.
• Route E Typical procedure for the preparation of pyrimidines as exemplified by the preparation of Example 36, 4-(3-(methylamino)azetidin-1-yl)-6-(1H-pyrazol-3-yl)pyrimidin-2-amine 4,6-Dichloropyrimidin-2-amine Intermediate 1 (1 g, 12.0 mmol), 3-(4,4,5,5-tetramethyl-1,3,2- dioxaborolan-2-yl)-1H-pyrazole Intermediate 44 (1.40 g, 7.20 mmol) and K 3 PO 4 (3.88 g, 18.9 mmol) were dissolved in 1,4-dioxane (20 mL) and water (4 mL) under nitrogen and degassed for 20 min.
• Example 36 (151 mg, 37.3%) as a white solid.
• the data for Example 36 are in Table 3.
• reaction mixture was diluted with H 2 O (50 mL), the aqueous layer was acidified by adding 1N HCl solution (30 mL), extracted with EtOAc (3 x 100 mL) and the combined organic layers were washed with brine solution (50 mL), dried over Na 2 SO 4 , filtered and concentrated to give crude product, which was purified by column chromatography (Silica gel; 60-120 mesh; 0-40% EtOAc/Hexane) to give ethyl 3-(5-ethyl-4-methyl-1H-pyrazol-3-yl)-3-oxopropanoate (0.71 g, 65%) as an off-white solid.
• reaction mixture was poured into an ice bath, neutralized by adding solid NaHCO 3 , the aqueous layer was extracted with EtOAc (3 x 50 mL) and the combined organic layers were washed with brine solution (50 mL), dried over Na 2 SO 4, filtered and concentrated to give a crude residue which was purified by column chromatography (Silica gel; 60-120 mesh; 0-40% EtOAc/Hexane) to give 4- chloro-6-(5-ethyl-4-methyl-1H-pyrazol-3-yl) pyrimidin-2-amine (401 mg, 54%) as a yellow solid.
• H4 ligands were prepared in DMSO and stamped by LabCyte ECHO acoustic dispensing at 25 nL in low volume plates. 10 ⁇ L/well cells were plated in the presence of 1 ⁇ M forskolin, subjected to centrifugation at 1,200 rpm for 1 min and incubated for 30 min prior to addition of Cisbio cAMP detection reagents to a total volume 20 ⁇ L/well.
• H4 Antagonist Functional Dynamic Mass Redistribution Assay HEKf cells were infected using baculovirus expressing the human H4 receptor, plated into fibronectin- coated EPIC plates at a density of 10,000 cells/well and incubated overnight at 37 °C. The medium on cells was changed to 30 ⁇ L HBSS with 20 mM HEPES per well and 30 nL DMSO were added per well by LabCyte ECHO acoustic dispensing.
• H4 ligands prepared in DMSO were stamped by LabCyte ECHO acoustic dispensing into seeded EPIC plates and cellular dynamic mass redistribution was monitored using a Corning EPIC plate reader.
• 30 nL/well of histamine EC80 was added and monitored to obtain antagonist assay data.
• Maximum baseline-corrected responses in pm were used to generate concentration response curves.
• EC50 values were generated using a 4-parameter logistical fit equation to quantify agonist potencies.
• Functional antagonist affinity values were generated using the Cheng-Prusoff equation to calculate a pKb value using the antagonist assay data.
• hERG Assay data was determined by Metrion Biosciences, Cambridge, UK, using the experimental protocols detailed below: A Chinese Hamster Ovary (CHO) cell line stably expressing the human ether-á-go-go related gene was grown and passaged under standard culture conditions. Cells were prepared for assays using dissociation protocols designed to optimise cell health, yield, and seal and assay quality. Test samples were provided as 10 mM stock solutions in 100% DMSO. All sample handling and serial dilutions were performed using glass containers and glass-lined plates. A top working concentration of 30 ⁇ M was prepared from the 10 mM sample stock solution using a 1:333-fold dilution into external recording solution (0.3% DMSO v/v).
• test samples were screened at 30 ⁇ M against a minimum of three separate cells.
• test samples were screened at 1, 3, 10 and 30 ⁇ M against a minimum of three separate cells.
• Each four-point concentration- response curve was constructed using cumulative double sample additions of each concentration to the same cell. All experiments were performed on the QPatch automated patch clamp platform. The composition of external and internal recording solutions for the QPatch experiments is shown in Table A below. All solutions were filtered (0.2 ⁇ m) prior to each experiment.
• Table A The composition of external and internal solutions (in mM) used in the hERG study All recordings were made in the conventional whole-cell configuration and performed at room temperature ( ⁇ 21 °C) using standard single hole chips (Rchip 1.5 - 4 M ⁇ ). Series resistance (4 - 15 M ⁇ ) was compensated by > 80 %. Currents were elicited from a holding potential of -90 mV using the industry standard “+40 / -40” voltage protocol as shown below; this was applied at a stimulus frequency of 0.1 Hz.
• Peak outward tail current amplitude elicited during the test pulse to -40 mV was measured relative to the instantaneous leak current measured during the initial pre-pulse step to -40 mV.
• the minimum current amplitude for the assay is > 200 pA peak outward current, measured at the end of the vehicle period.
• the QPatch analysis software calculates the mean peak current for the last three sweeps at the end of each concentration application period and the data is exported to Excel and interrogated using a bioinformatics suite developed running in Pipeline Pilot (Biovia, USA).
• the template calculates percent inhibition for each test concentration application period as the reduction in mean peak current or charge relative to the value measured at the end of the control (i.e. vehicle) period.
• the percent inhibition values from each cell are used to construct concentration-response curves employing a four-parameter logistic fit with 0 and 100% inhibition levels fixed at very low and very high concentrations, respectively, and a free Hill slope factor.
• the IC 50 (50% inhibitory concentration) and Hill coefficient are then determined, but only data from cells with Hill slopes within 0.5 > nH ⁇ 2.0 are included.
• the IC 50 data reported below represents the mean of at least three separate cells (N ⁇ 3). By convention, a test sample that fails to achieve > 40% block at the top concentration will yield an ambiguous IC 50 value due to a poor or unconstrained fit. In this instance an arbitrary IC 50 value is returned that is 0.5 log unit above the highest concentration tested.

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