WO2009016227A2 - Novel compounds - Google Patents

Abstract

The present invention relates to novel indoline derivatives which bind to the 5-HT2B receptor and are capable of interfering with the effects of 5-hydroxytryptamine (5-HT) at the 5-HT2B receptor; to processes for their preparation; to pharmaceutical compositions containing them; and to the use of such compounds in therapy.

Description

NOVEL COMPOUNDS

The present invention relates to novel indoline derivatives which bind to the 5-HT_2B receptor and are capable of interfering with the effects of 5-hydroxytryptamine (5-HT) at the 5-HT_2B receptor; to processes for their preparation; to pharmaceutical compositions containing them; and to the use of such compounds in therapy.

5-Hydroxytryptamine (5-HT, or serotonin) is a neurotransmitter important to both the central nervous system (CNS) and as a pivotal mediator of sensory and motor function in the gastrointestinal (Gl) tract, McLean et ai, TRENDS in Neurosciences (2006) Vol.30 No.1 , 9-13. When first isolated, serotonin was referred to as 'gut- stimulating factor', Erspamer et ai, Nature (1952) Vol.169, 800-801 , and since that time has also become appreciated as a neurotransmitter in the brain. The cell surface receptors via which serotonin exerts its biological effects have been identified by molecular techniques. These receptors can be subdivided into at least 7 distinct subfamilies termed 5-HT₁, 5-HT_2, 5-HT₃, 5-HT₄, 5-HT₅, 5-HT₆ and 5-HT₇ based on gene sequence, pharmacological profile and signal transduction pathways, Robichaud et ai, Annual Reports in Medicinal Chemistry (2000) Vol.36, 11-20.

5-HT₂ receptors are a family of seven transmembrane domain G-protein coupled receptors which can be subdivided into three distinct subtypes: 5-HT_2A, 5-HT₂₆ and 5- HT_2C, sharing an overall amino acid homology of approximately 50% and the homology within the transmembrane domains being greater than 70%, J. E. Leysen, Current Drug Targets - CNS & Neurological Disorders (2004), Vol.3, 11-26.

5-HT_2B receptors are present on both smooth muscle and nerves and their activation by serotonin can cause direct smooth muscle contraction in the human ileum, Borman et ai, British Journal of Pharmacology (1995) Vol.114, 1525-1527. Furthermore, activation of 5-HT_2B receptors can enhance cholinergic-neuron- mediated contractions in human colon (Borman et ai, British Journal of

Pharmacology (2002) Vol. 135, 1 144-1151 ; WO 2005/097113; and WO 02/056010). These studies suggest that blockade of 5-HT_2B receptors could reduce the prokinetic effects of serotonin on the Gl tract and thus 5-HT₂₆ receptor antagonists may be of use in the treatment of functional bowel disorders such as Irritable Bowel Syndrome (IBS). Visceral pain is commonly associated with IBS, the most frequent features of which are recurrent abdominal pain and discomfort, altered bowel habits and a strong female predominance. The definition and criteria for IBS have been formalised by the Rome III criteria, Drossman et ai, Journal of Gastrointestinal and Liver Diseases (2006) Vol.15(3), 237-241. The potential usefulness of 5-HT_2B receptors in the treatment of IBS is further supported by the observation that the 5-HT₄ agonist

Tegaserod (Novartis) and the 5-HT₃ antagonist Alosetron (GlaxoSmithKline), both of which are used for the management of IBS, also have affinity for the 5-HT₂₆ receptor. IBS may also be treated with gabapentin or the tricyclic antidepressant drug amitriptyline. A study by Poitras et al., Digestive Diseases and Sciences (2002), Vol.47(4), 914-920, suggested that amitriptyline was effective in decreasing the clinical symptomatology of IBS and that this clinical improvement was correlated to the modulation of visceral pain perception. Gabapentin, on the other hand, is widely used as a medication to relieve pain and has been shown to reduce rectal sensory thresholds through attenuating rectal sensitivity to distension and enhancing rectal compliance in diarrhoea-predominant IBS patients, Lee et al., Alimentary Pharmacology and Therapeutics (2005), Vol.22, 981-988.

There is also some evidence that 5-HT_2B receptor blockade is involved in migraine since the experimental drug tool m-chlorophenylpiperazine that triggers migraine in selected subjects has affinity for both the 5-HT_2B receptor and the 5-HT_2C receptor, Fozard et al., Naunyn-Schmiedeberg's Arch Pharmacol (1994) Vol. 250, 225-229, as do a number of migraine prophylactic drugs, Kalkman Life Sciences (1994) Vol.54(10), 641-644.

It has also been demonstrated in both humans and mice that pulmonary hypertension is associated with a substantial increase in 5-HT_2B receptor expression in pulmonary arteries. These data show that activation of 5-HT_2B receptors is a limiting step in the development of pulmonary hypertension (Launay, J. -M. et al., (2002) Nature Medicine 8(10), 1 129-1135).

As well as being implicated in migraine, studies in 5-HT_2C receptor-knockout mice suggest that the 5-HT_2C receptor may also be involved in obesity and epilepsy, Tecott et al. Nature (1995) Vol.374, 542-546. In addition, the 5-HT_2C receptor is closely involved in the weight gain that occurs following treatment with many antipsychotic drugs, for example clozapine and olanzapine, and is likely to contribute directly via the 5-HT_2C antagonistic effects of these drugs, Reynolds et al., Journal of Psychopharmacology (2006) Vol. 20, 15-18.

Animal models of human disease are commonly used to predict the effectiveness of a test pharmaceutical compound in treating humans. One such animal model is the intra rectal mustard oil model of visceral pain described by Laird et al. in Pain 2001 ; 92: 335-342. Mustard oil has been used in a variety of conscious and anaesthetised models to elicit pain or stimulate nociceptive pathways.

5-HT_2B receptor activation is also believed to influence mitogenic signalling. This activity is thought to underpin the reason why 5-HT₂₆ receptor antagonists are likely to provide useful treatments of conditions associated with the development of fibrosis, including valvular heart diseases, pulmonary hypertension and lung and liver fibrosis. The evidence pointing to a link between the 5-HT₂₆ receptor and the various cardiovascular diseases is summarised by Kaumann & Levy (2006, Pharmacology & Therapeutics, 1 11 , 674-706) and specifically described by Jaffre et al (2004, Circulation, 110, 969-974) and Launay et al (2002, Nature Medicine, 8, 1129-1 135). The evidence pointing to a link with lung fibrosis is exemplified by Fabre et al (2008, Eur Respiratory Journal., doi 10.1 183/09031936.00126907), and that to liver fibrosis by Ruddell et al (2006, Am J Pathol, 169, 861-76), where high expression in hepatic stellate cells may be associated with liver fibrosis. Interestingly, 5-HT_2B receptors are also thought to limit the regenerative capacity of liver hepatocytes, suggesting that 5- HT_2B receptor antagonists will be useful in promoting liver regeneration in end stage liver disease (Ebrahimkhani et al, 2007, Hepatology, 46, S1 , 786A).

WO 2006/038006 (Glaxo Group Limited) describes a series of indole and indoline derivatives as 5-HT₆ antagonists.

The present invention provides compounds with affinity for the 5-HT_2B receptor and which are capable of interfering with the affects of serotonin at these receptors. In a first aspect there is provided a compound of formula (I), or a pharmaceutically acceptable salt thereof:

(I) wherein:

R¹ represents a nitrogen containing heterocyclyl group selected from pyrrolidinyl, piperidinyl, morpholinyl, hexahydro-1 ,4-oxazepine or hexahydro-1/-/-azepine, wherein the nitrogen atom of the nitrogen containing heterocyclyl group is linked to the sulfur atom of the SO₂ moiety, and wherein each of said heterocyclyl groups may be optionally substituted by one or more (e.g. 1 , 2 or 3) fluorine atoms; n represents an integer selected from 1 or 2; and R² represents hydrogen or Ci_-3 alkyl.

As used herein, the term "alkyl" (when used as a group or as part of a group) refers to a straight or branched hydrocarbon chain containing the specified number of carbon atoms. For example, C_1-3 alkyl means a straight or branched hydrocarbon chain containing at least 1 and at most 3 carbon atoms. Examples of alkyl include methyl (Me), ethyl (Et), n-propyl and i-propyl.

In certain embodiments of the invention, R¹ represents piperidinyl optionally substituted by one or more (e.g. 1 or 2) fluorine atoms. In other embodiments of the invention, R¹ represents unsubstituted piperidinyl.

In certain embodiments of the invention, R² represents hydrogen, methyl or ethyl. In a further embodiment, R² represents hydrogen or ethyl. In a yet further embodiment, R² represents hydrogen.

In one embodiment, the compound of formula (I) is selected from:

6-[(3,3-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 H-indole;

6-[(4,4-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 /-/-indole; 1-(4-Piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole;

1-(4-Piperidinyl)-6-(tetrahydro-1 ,4-oxazepin-4(5H)-ylsulfonyl)-2,3-dihydro-1 H-indole;

6-[(4-Fluoro-1 -piperidinyl)sulfonyl]-1 -(4-piperidinyl)-2,3-dihydro-1 H-indole:

1-(4-Piperidinyl)-6-(1-pyrrolidinylsulfonyl)-2,3-dihydro-1 H-indole;

6-(Hexahydro-1 H-azepin-1-ylsulfonyl)-1-(4-piperidinyl)-2,3-dihydro-1 H-indole; 6-(4-Morpholinylsulfonyl)-1-(4-piperidinyl)-2,3-dihydro-1 H-indole:

1-(1-Ethyl-4-piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole; or

6-[(3,3-Difluoro-1-piperidinyl)sulfonyl]-1-(3-pyrrolidinyl)-2,3-dihydro-1 H-indole; or a pharmaceutically acceptable salt thereof.

In a further embodiment, the compound of formula (I) is selected from:

6-[(3,3-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E1 );

6-[(4,4-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E2); 1-(4-Piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole hydrochloride (E3);

1 -(4-Piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole (E3A);

1-(4-Piperidinyl)-6-(tetrahydro-1 ,4-oxazepin-4(5H)-ylsulfonyl)-2,3-dihydro-1 H-indole hydrochloride (E4);

6-[(4-Fluoro-1 -piperidinyl)sulfonyl]-1 -(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E5);

1-(4-Piperidinyl)-6-(1-pyrrolidinylsulfonyl)-2,3-dihydro-1 H-indole hydrochloride (E6);

6-(Hexahydro-1 H-azepin-1-ylsulfonyl)-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E7);

6-(4-Morpholinylsulfonyl)-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E8); 1-(1-Ethyl-4-piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole (E9); or

6-[(3,3-Difluoro-1-piperidinyl)sulfonyl]-1-(3-pyrrolidinyl)-2,3-dihydro-1 H-indole hydrochloride (E10).

Antagonists of the 5-HT_2B receptor may be useful in preventing, treating or ameliorating Gl tract disorders, for example IBS. 5-HT_2B receptor antagonists may also be useful in preventing, treating or ameliorating pain, for example inflammatory pain or visceral pain. In addition, 5-HT₂₆ receptor antagonists may be useful in preventing, treating or ameliorating certain CNS disorders including migraine. 5-HT_2B receptor antagonists may also be useful in preventing, treating or ameliorating certain cardiovascular disorders including pulmonary arterial hypertension.

In one embodiment of the invention, a method of treatment of inflammatory pain in mammals is provided, which method comprises the administration to the mammal in need of such treatment, an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof.

The cause of such inflammatory pain may be osteoarthritis or rheumatoid arthritis. There is therefore provided in one embodiment of the invention, a method of treatment of chronic articular pain associated with osteoarthritis or rheumatoid arthritis in mammals, which method comprises the administration to the mammal in need of such treatment, an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof.

In another embodiment of the invention, a method of treatment of visceral pain in mammals is provided, which method comprises the administration to the mammal in need of such treatment, an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof. In one embodiment of the invention, the visceral pain is associated with irritable bowel syndrome.

In another embodiment of the invention, a method of treatment of irritable bowel syndrome in mammals is provided, which method comprises the administration to the mammal in need of such treatment, an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof.

In another embodiment of the invention, a method of treatment of headache (e.g. migraine) is provided, which method comprises the administration to the mammal in need of such treatment, an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof.

In another embodiment of the invention, a method of treatment of fibrosis or a fibrotic condition is provided, which method comprises the administration to the mammal in need of such treatment, an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof.

In one embodiment of the invention, the mammal in need of such treatment is human. In a further embodiment of the invention, the human is female.

As used herein, the term "fibrosis" refers to the formation or development of excess fibrous connective tissue in an organ or tissue as a reparative or reactive process, as opposed to a formation of fibrous tissue as a normal constituent of an organ or tissue. Similarly, the term "fibrotic condition" refers to a disease or condition mediated by fibrosis. Examples of types of fibrotic conditions and associated conditions include but are not limited to cardiovascular disorders (e.g. valvular heart diseases, conditions associated with cardiac hypertrophy and pulmonary hypertension), lung fibrosis (e.g. after chronic obstructive pulmonary disease), liver fibrosis (e.g. precirrhotic alcoholic liver disease, nonalcoholic steatohepatitis/ fatty liver disease and hepatitis C), cystic fibrosis (such as cystic fibrosis of the pancreas and lungs), injection fibrosis (such as fibrotic conditions which can occur as a complication of intramuscular injections, especially in children), fibrosis which follows organ transplant or other therapeutic regimens, such as anti-cancer treatment with radiation, schleroderma, endomyocardial fibrosis, idiopathic pulmonary fibrosis, mediastinal fibrosis, myleofibrosis, retroperitoneal fibrosis, progressive massive fibrosis, nephrogenic systemic fibrosis, cirrhosis, diffuse parenchymal lung disease, post-vasectomy pain syndrome, tuberculosis, sickle-cell anemia and rheumatoid arthritis. In one embodiment, the fibrotic condition is a cardiovascular disorder (e.g. valvular heart diseases, conditions associated with cardiac hypertrophy and pulmonary hypertension), lung fibrosis (e.g. after chronic obstructive pulmonary disease) or liver fibrosis (e.g. precirrhotic alcoholic liver disease, nonalcoholic steatohepatitis/ fatty liver disease and hepatitis C).

As used herein, the term "pain" refers to any unpleasant sensation that is perceived by the individual and includes, but is not limited to, acute pain, chronic pain, somatic pain (originating from ligaments, tendons, bones, blood vessels or nerves), chronic articular pain, musculoskeletal pain, neuropathic pain, inflammatory pain, visceral pain, pain associated with cancer, pain associated with migraine, tension headache and cluster headaches, pain associated with functional bowel disorders, lower back and neck pain, pain associated with sprains and strains, sympathetically maintained pain; myositis, pain associated with influenza or other viral infections such as the common cold, pain associated with rheumatic fever, pain associated with myocardial ischemia, post operative pain, cancer chemotherapy, headache, toothache and dysmenorrhea.

As used herein, the term "inflammatory pain" refers to any kind of pain that results from the inflammation of bodily tissues and includes, but is not limited to, inflammation resulting from soft tissue damage or infection.

As used herein, the term "neuropathic pain" refers to any kind of pain that results from injury or disease to the nerve tissue itself and includes, but is not limited to: diabetic neuropathy, sciatica, non-specific lower back pain, trigeminal neuralgia, multiple sclerosis pain, fibromyalgia, HIV-related neuropathy, post-herpetic neuralgia, trigeminal neuralgia, and pain resulting from physical trauma, amputation, phantom limb syndrome, spinal surgery, cancer, toxins or chronic inflammatory conditions. In addition, neuropathic pain conditions include pain associated with normally non- painful sensations such as "pins and needles" (paraesthesias and dysesthesias), increased sensitivity to touch (hyperesthesia), painful sensation following innocuous stimulation (dynamic, static, thermal or cold allodynia), increased sensitivity to noxious stimuli (thermal, cold, mechanical hyperalgesia), continuing pain sensation after removal of the stimulation (hyperpathia) or an absence of or deficit in selective sensory pathways (hypoalgesia).

As used herein, the term "visceral pain" refers to any kind of pain that originates from the body's internal cavities or organs and includes, but is not limited to, pain that originates from the intestines.

As used herein, the term "Irritable Bowel Syndrome" (IBS) is defined according to the Rome III diagnostic criteria where the criteria are fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis. The Rome III diagnostic criteria for IBS are as follows: - Recurrent abdominal pain or discomfort (where discomfort means an uncomfortable sensation not described as pain) at least 3 days per month in the last 3 months associated with 2 or more of the following:

1. Improvement with defecation;

2. Onset associated with a change in frequency of stool; 3. Onset associated with a change in form (appearance) of stool.

Other symptoms that are not essential but support the diagnosis of IBS include:

Abnormal stool frequency (greater than 3 bowel movements/day or less than

3 bowel movements/week);

Abnormal stool form (lumpy/hard or loose watery stool); - Abnormal stool passage (straining, urgency, or feeling of incomplete bowel movement):

Passage of mucous;

Bloating or feeling of abdominal distension.

As used herein, the term "headache" refers to any unpleasant sensation that is localised to the individual's head and includes, but is not limited to, migraine, tension headache and cluster headaches.

The term "treatment" or "treating" as used herein includes the treatment of established disorders and also includes the prophylaxis thereof. The term

"prophylaxis" is used herein to mean preventing symptoms in an already afflicted subject or preventing recurrence of symptoms in an afflicted subject and is not limited to complete prevention of an affliction.

Compounds of the present invention interact with the 5-HT_2B receptor and are capable of interfering with the effects of serotonin at the 5-HT_2B receptor. Such compounds may be competitive antagonists, inverse agonists, or negative allosteric modulators. Certain compounds of formula (I) exhibit selectivity for the 5-HT_2B receptor over certain other serotonin receptors (e.g. 5-HT_2A, 5-HT_2C and/or 5-HT₆). In one embodiment, compounds of formula (I) exhibit 10 fold selectivity for the 5-HT_2B receptor over the 5-HT_2A, 5-HT_2C and/or 5-HT₆ receptors. In a further embodiment, compounds of formula (I) exhibit 50 fold selectivity for the 5-HT₂₆ receptor over the 5- HT_2A, 5-HT_2C and/or 5-HT₆ receptors.

Certain compounds of formula (I) may in some circumstances form acid addition salts thereof. It will be appreciated that for use in medicine compounds of formula (I) may be used as salts, in which case the salts should be pharmaceutically acceptable. Pharmaceutically acceptable salts include those described by Berge, Bighley and Monkhouse , J. Pharm. ScL, 1977, 66, 1-19. The term "pharmaceutically acceptable salts" includes salts prepared from pharmaceutically acceptable acids, including inorganic and organic acids. Such acids include acetic, benzenesulfonic, benzoic, camphorsulfonic, citric, ethanesulfonic, fumaric, gluconic, glutamic, hydrobromic, hydrochloric, isethionic, lactic, maleic, malic, mandelic, methanesulfonic, mucic, nitric, pamoic, pantothenic, phosphoric, succinic, sulfuric, tartaric, p-toluenesulfonic acid, and the like.

Examples of pharmaceutically acceptable salts include those formed from maleic, fumaric, benzoic, ascorbic, pamoic, succinic, hydrochloric, sulfuric, bismethylenesalicylic, methanesulfonic, ethanedisulfonic, propionic, tartaric, salicylic, citric, gluconic, aspartic, stearic, palmitic, itaconic, glycolic, p-aminobenzoic, glutamic, benzenesulfonic, cyclohexylsulfamic, phosphoric and nitric acids.

The compounds of formula (I) may be prepared in crystalline or non-crystalline form, and, if crystalline, may optionally be solvated, e.g. as the hydrate. This invention includes within its scope stoichiometric solvates (e.g. hydrates) as well as compounds containing variable amounts of solvent (e.g. water).

Certain compounds of formula (I) are capable of existing in stereoisomeric forms (e.g. diastereomers and enantiomers) and the invention extends to each of these stereoisomeric forms and to mixtures thereof including racemates. The different stereoisomeric forms may be separated one from the other by the usual methods, or any given isomer may be obtained by stereospecific or asymmetric synthesis. The invention also extends to any tautomeric forms and mixtures thereof.

The subject invention also includes isotopically-labeled compounds, which are identical to those recited in formula (I) and following, but for the fact that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number most commonly found in nature. Examples of isotopes that can be incorporated into compounds of the invention include isotopes of hydrogen, carbon, nitrogen, fluorine, such as 3H, 1 1 C, 14C and 18F.

Compounds of the present invention and pharmaceutically acceptable salts of said compounds that contain the aforementioned isotopes and/or other isotopes of other atoms are within the scope of the present invention. Isotopically-labeled compounds of the present invention, for example those into which radioactive isotopes such as 3H, 14C are incorporated, are useful in drug and/or substrate tissue distribution assays. Tritiated, i.e., 3H, and carbon-14, i.e., 14C, isotopes are particularly preferred for their ease of preparation and detectability. 1 1 C and 8F isotopes are particularly useful in PET (positron emission tomography). PET is useful in brain imaging. Further, substitution with heavier isotopes such as deuterium, i.e., 2H, can afford certain therapeutic advantages resulting from greater metabolic stability, for example increased in vivo half-life or reduced dosage requirements and, hence, may be preferred in some circumstances, lsotopically labeled compounds of formula (I) and following of this invention can generally be prepared by carrying out the procedures disclosed in the Schemes and/or in the Examples below, by substituting a readily available isotopically labeled reagent for a non-isotopically labeled reagent.

It is to be understood that reference to treatment includes both treatment of established symptoms and prophylactic treatment, unless explicitly stated otherwise.

According to a further aspect of the invention there is provided a compound of formula (I) or a pharmaceutically acceptable salt thereof for use in therapy.

According to a further aspect of the invention there is provided a compound of formula (I) or a pharmaceutically acceptable salt thereof for use in the treatment of fibrosis or a fibrotic condition, Gl tract disorders, for example IBS, pain, for example inflammatory pain or visceral pain, headache, for example migraine, cardiovascular disorders including pulmonary arterial hypertension. In one embodiment, there is provided a compound of formula (I) or a pharmaceutically acceptable salt thereof for use in the treatment of fibrosis or a fibrotic condition.

According to a further aspect of the invention there is provided the use of a compound of formula (I) or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for the treatment of fibrosis or a fibrotic condition, Gl tract disorders, for example IBS, pain, for example inflammatory pain or visceral pain, headache, for example migraine, cardiovascular disorders including pulmonary arterial hypertension. In one embodiment, there is provided the use of a compound of formula (I) or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for the treatment of fibrosis or a fibrotic condition. According to a further aspect of the invention there is provided a pharmaceutical composition for use in the treatment of fibrosis or a fibrotic condition, Gl tract disorders, for example IBS, pain, for example inflammatory pain or visceral pain, headache, for example migraine, cardiovascular disorders including pulmonary arterial hypertension which comprises the compound of formula (I) or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier. In one embodiment, there is provided a pharmaceutical composition for use in the treatment of fibrosis or a fibrotic condition which comprises the compound of formula (I) or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier.

In order to use a compound of formula (I) or a pharmaceutically acceptable salt thereof for the treatment of humans and other mammals it is normally formulated in accordance with standard pharmaceutical practice as a pharmaceutical composition. Therefore in another aspect of the invention there is provided a pharmaceutical composition comprising a compound of formula (I), or a pharmaceutically acceptable salt thereof, for use in human or veterinary medicine.

In order to use the compounds of formula (I) in therapy, they will normally be formulated into a pharmaceutical composition in accordance with standard pharmaceutical practice. The present invention also provides a pharmaceutical composition, which comprises a compound of formula (I), or a pharmaceutically acceptable salt thereof, and optionally a pharmaceutically acceptable carrier.

A pharmaceutical composition of the invention, which may be prepared by admixture, suitably at ambient temperature and atmospheric pressure, is usually adapted for oral, parenteral or rectal administration and, as such, may be in the form of tablets, capsules, oral liquid preparations, powders, granules, lozenges, reconstitutable powders, injectable or infusable solutions or suspensions or suppositories. Orally administrable compositions are generally preferred.

Tablets and capsules for oral administration may be in unit dose form, and may contain conventional excipients, such as binding agents, fillers, tabletting lubricants, disintegrants and acceptable wetting agents. The tablets may be coated according to methods well known in normal pharmaceutical practice.

Oral liquid preparations may be in the form of, for example, aqueous or oily suspension, solutions, emulsions, syrups or elixirs, or may be in the form of a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations may contain conventional additives such as suspending agents, emulsifying agents, non-aqueous vehicles (which may include edible oils), preservatives, and, if desired, conventional flavourings or colourants. For parenteral administration, fluid unit dosage forms are prepared utilising a compound of the invention or pharmaceutically acceptable salt thereof and a sterile vehicle. The compound, depending on the vehicle and concentration used, can be either suspended or dissolved in the vehicle. In preparing solutions, the compound can be dissolved for injection and filter sterilised before filling into a suitable vial or ampoule and sealing. Advantageously, adjuvants such as a local anaesthetic, preservatives and buffering agents are dissolved in the vehicle. To enhance the stability, the composition can be frozen after filling into the vial and the water removed under vacuum. Parenteral suspensions are prepared in substantially the same manner, except that the compound is suspended in the vehicle instead of being dissolved, and sterilization cannot be accomplished by filtration. The compound can be sterilised by exposure to ethylene oxide before suspension in a sterile vehicle. Advantageously, a surfactant or wetting agent is included in the composition to facilitate uniform distribution of the compound.

The composition may contain from 0.1% to 99% by weight, preferably from 10 to 60% by weight, of the active material, depending on the method of administration.

The dose of the compound used in the treatment of the disorders mentioned herein will vary in the usual way with the seriousness of the disorders, the weight of the sufferer, and other similar factors. However, as a general guide suitable unit doses may be 0.05 to 1000 mg, more suitably 0.05 to 200 mg; and such unit doses will preferably be administered once a day, although administration more than once a day may be required; and such therapy may extend for a number of weeks, months or even years. In addition, such therapy could be given on demand, prophylactically, or continuously over a period of time until the patient no longer requires treatment.

The present invention also provides a process for the preparation of a compound of formula (I) or a pharmaceutically acceptable salt thereof, which process comprises:

(a) reaction of a compound of formula (II)

(H) with a compound of formula R¹-H, wherein R¹ is as defined above and L¹ represents a suitable leaving group such as chlorine and P¹ represents a suitable protecting group, such as -COCF₃; and thereafter followed by (b) deprotecting a compound of formula (I) which is protected; and optionally thereafter followed by

(c) interconversion to other compounds of formula (I).

Process (a) may typically be performed in the presence of a suitable base such as triethylamine in a suitable solvent such as dichloromethane.

In process (b), examples of protecting groups and the means for their removal can be found in T. W. Greene 'Protective Groups in Organic Synthesis' (J. Wiley and Sons, 1991 ). Suitable amine protecting groups include sulfonyl (e.g. tosyl), acyl (e.g. acetyl, 2',2',2'-trichloroethoxycarbonyl, benzyloxycarbonyl or t-butoxycarbonyl) and arylalkyl (e.g. benzyl), which may be removed by hydrolysis (e.g. using an acid such as hydrochloric acid in dioxan or trifluoroacetic acid in dichloromethane) or reductively (e.g. hydrogenolysis of a benzyl group or reductive removal of a 2',2',2'- trichloroethoxycarbonyl group using zinc in acetic acid) as appropriate. Other suitable amine protecting groups include trifluoroacetyl (-COCF₃) which may be removed by base catalysed hydrolysis (e.g. treatment with ammonia in methanol) or a solid phase resin bound benzyl group, such as a Merrifield resin bound 2,6-dimethoxybenzyl group (Ellman linker), which may be removed by acid catalysed hydrolysis, for example with trifluoroacetic acid.

Process (c) may be performed using conventional interconversion procedures such as alkylation or reductive amination. One example of such interconversion includes alkylation of compounds of formula (I) wherein R² represents hydrogen to compounds of formula (I) wherein R² represents Ci_-3 alkyl by reaction with an alkyl halide in the presence of a suitable base. A further example of such interconversion includes de-alkylation of compounds of formula (I) wherein R² represents C_1-3 alkyl to compounds of formula (I) wherein R² represents hydrogen by reaction with a suitable chloroformate reagent.

Compounds of formula (II) wherein n represents 2 may be prepared in accordance with the following scheme:

Scheme 1

wherein L¹ and P¹ are as defined above and P² represents a suitable protecting group, e.g. Boc.

Step 1 may typically be performed by reductive amination of a compound of formula (IV) with a compound of formula (III) using sodium triacetoxyborohydride in acetic acid optionally in the presence of a co-solvent such as 1 ,2-dichloroethane.

When P² represents Boc, step 2 may typically be performed under suitable acidic conditions, for example by treatment with HCI in 1 ,4-dioxane in a suitable solvent such as methanol.

When P¹ represents -COCF₃, step 3 may typically be performed by treatment of a compound of formula (Vl) with trifluoroacetic anhydride in the presence of a base such as triethylamine in a suitable solvent such as dichloromethane.

When L¹ represents chlorine, step 4 may typically be performed using chlorosulfonic acid at elevated temperature.

It will be appreciated by the skilled person that compounds of formula (II) wherein n represents 1 may be prepared in an analogous manner to the procedures described in Scheme 1.

Compounds of formula (III) and (IV) are either known or may be prepared in accordance with known procedures.

The following Intermediates and Examples illustrate the preparation of compounds of the invention.

Intermediate 1

1 ,1 -Dimethylethyl 4-(2,3-dihydro-1 H-indol-1 -yl)-1 -piperidinecarboxylate

To a solution of indoline (Acros, 1Og, 83.91 mmol) in 1 ,2-DCE (20OmL) under argon, cooled in ice was added 1-Boc-4-piperidinone (Fluka, 16.72g, 83.91 mmol) and acetic acid (4.8ml_, 83.91 mmol). After stirring for 10 minutes sodium triacetoxyborohydride (26.68g, 125.87mmol) was added portionwise, keeping the temperature below 10°C. The flask was then removed from the ice bath and stirring under argon at room temperature was continued for 65 hours. The solvent was removed in vacuo and the residue was taken up in ethyl acetate (40OmL) and washed with saturated aqueous sodium bicarbonate solution (3x10OmL). The ethyl acetate layer was dried over sodium sulfate, filtered and concentrated in vacuo to afford the title compound as a pale brown oil (27.52g, 100%).

¹H NMR (CDCI₃, 400MHz): δ 1.47 (9H, s), 1.50-1.68 (4H, m, integration slightly obscured by adjacent peak), 1.74-1.86 (2H, m), 2.78 (2H, br.m), 2.94 (2H, t, J=8.5), 3.34 (2H, t, J=8.5), 3.51 (1 H, tt, J=1 1.5, 3.5), 6.42 (1 H, d, J=7.5), 6.61 (1 H, dd, J=7.5, 1.0) 7.01-7.09 (2H, m). Mass spectrum (ESI): Ci₈H₂₆N₂O₂ requires 302; found 303 (MH⁺).

Intermediate 1 (Alternative Procedure) 1 ,1 -Dimethylethyl 4-(2,3-dihydro-1 H-indol-1 -yl)-1 -piperidinecarboxylate

1-Boc-4-piperidinone (34g, 172mmol) was added to a solution of indoline (18.6g, 156mmol) in acetic acid (35OmL) under argon. The reaction was cooled in an ice bath and sodium triacetoxyborohydride (5Og, 234mmol) was added portionwise, the internal temperature remaining below 25⁰C. The mixture was stirred at room temperature for 1 hour then evaporated to minimum volume. The residue was taken up in ethyl acetate (70OmL), washed with saturated aqueous sodium bicarbonate solution (3x200mL) then dried over magnesium sulfate and evaporated to give the title compound as a pale yellow oil (49g, >100%).

Intermediate 2

1-(4-Piperidinyl)-2,3-dihydro-1H-indole hydrochloride

A solution of 4M HCI/dioxan (5OmL) was added to an ice-cooled solution of 1 ,1- dimethylethyl 4-(2,3-dihydro-1 H-indol-1 -yl)-1 -piperidinecarboxylate (may be prepared as described for Intermediate 1 , 27.52g, 91 mmol) in methanol (5OmL). The reaction was then stirred at room temperature under argon overnight. The solvent was removed in vacuo and the resultant beige solid was redissolved in methanol (6OmL) and treated with fresh 4M HCI/dioxan (5OmL). After stirring at room temperature for 1 hour, the solvent was removed in vacuo to afford the title compound as a beige solid (25.94g, 100%).

¹H NMR (MeOD, 400MHz): δ 2.04-2.26 (4H, m), 3.17 (2H, dt, J=13.0, 3.0), 3.28-3.32 (2H, m), 3.36 (2H, t, J=7.5), 3.53-3.60 (2H, m), 4.02 (2H, t, J=7.5), 4.27 (1 H, dt, J=11.5, 4.5), 7.45-7.56 (3H, m), 7.59 (1 H, m). Mass spectrum (ESI): C₁₃H₁₈N₂-HCI requires 202; found 203 (MH⁺).

Intermediate 3

1 -[1 -(Trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole

F To an ice-cooled solution of triethylamine (38mL, 273mmol) in DCM (45OmL) was added 1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (which may be prepared as described for Intermediate 2, 91 mmol) portionwise with stirring. Then 1 ,4-dioxane (-4OmL) was added to aid solubility of intermediate 2. The mixture was stirred for 15 minutes then trifluoroacetic anhydride (16.45mL, 118mmol) was slowly added. The mixture was then allowed to warm to room temperature with stirring under argon overnight. Saturated aqueous sodium bicarbonate solution (15OmL) was then added to the mixture and it was transferred to a separating funnel. The DCM layer was isolated and washed with a further 15OmL saturated aqueous sodium bicarbonate solution followed by 2M aqueous HCI (15OmL). The DCM layer was dried over sodium sulfate, filtered and dried in vacuo to afford the title compound as a brown oil (20.56g, 75%).

¹H NMR (CDCI₃, 400MHz): δ 1.66 (2H, qt, J=12.5, 4.0), 1.98-2.16 (2H, m), 2.83 (1 H, dt, J=13.0, 2.0), 3.05 (2H, t, J=8.0), 3.22 (1 H, m), 3.46 (2H, t, J=8.0), 3.78 (1 H, m), 4.14 (1 H, m), 4.70 (1 H, m), 6.73 (1 H, d, 8.0), 6.86 (1 H, t, 7.5), 7.12-7.22 (2H, m). Mass spectrum (ESI): C₁₅H₁₇F₃N₂O requires 298; found 299 (MH⁺).

Intermediate 3 (Alternative Procedure)

1 -[1 -(Trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole 1 ,1-Dimethylethyl 4-(2,3-dihydro-1 H-indol-1-yl)-1-piperidinecarboxylate (which may be prepared as described for Intermediate 1 , 156mmol) was dissolved in methanol (10OmL). A solution of 4M HCI in dioxan (10OmL) was added and the reaction was stirred at room temperature under argon for 6 hours. Solvents were evaporated and the crude product was added to a solution of triethylamine (65ml_) in DCM. The mixture was stirred for 10 minutes then trifluoroacetic anhydride (28.2ml, 203mmol) was added. The reaction was stirred for 2 hours then a further 28ml_ of trifluoroacetic anhydride and 65ml_ of triethylamine was added. Stirring was continued for 5 hours. The reaction was transferred to a separating funnel, washed with saturated sodium bicarbonate (gas evolution) then dried over magnesium sulfate and evaporated. The residue was purified by flash chromatography on silica eluting with 0-10% ethyl acetate in hexanes. Clean fractions were collected and evaporated to give the title compound as a pale yellow oil that solidified on standing (27.5g).

Intermediate 4

1 -[1 -(Trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride

A solution of 1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole (which may be prepared as described for Intermediate 3, 20.56g, 69mmol) in chlorosulfonic acid (95ml_) was stirred under argon at 50⁰C overnight then at 80⁰C for 3 hours. The mixture was transferred to a dropping funnel and added dropwise to ~1 L of crushed ice (more ice added as needed) over 1.5 hours. The mixture was extracted with DCM (2x500ml_) and the combined DCM extracts were washed with saturated aqueous sodium bicarbonate solution (50OmL), dried over magnesium sulfate, filtered and concentrated in vacuo. The resultant beige solid was purified by flash chromatography on silica gel (75Og, Companion XL) eluting with a solvent gradient of

0 to 30% ethyl acetate/hexane. The resultant solid was triturated with hexane and dried in the vacuum oven to afford the title compound as a yellow solid (6.25g, 23%).

¹H NMR (CDCI₃, 400MHz): δ 1.61-1.76 (2H, m), 1.93-2.02 (2H, m), 2.89 (1 H, dt, J=13.0, 1.5), 3.09 (2H, dt, J=9.0, 1.0), 3.28 (1 H, m), 3.48-3.59 (2H, t, J=8.5, 1.0), 3.74 (1 H, tt, J=12.0, 4.0), 4.17 (1 H, m, integration partially obscured by ethyl acetate), 4.73 (1 H, m), 6.86 (1 H, s), 7.19 (1 H, dt, J=7.5, 1.0), 7.30 (1 H, dd, J=7.5, 2.0).

Mass spectrum (ESI): Ci₅H₁₆CIF₃N₂O₃S requires 396/398; found 397/399 (MH⁺).

Intermediate 4 (Alternative Procedure)

1 -[1 -(Trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride 1-[1-(Trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole (which may be prepared as described for Intermediate 3, 10g, 33.6mmol) was added portionwise to chlorosulfonic acid (4OmL). Once the addition was complete the mixture was heated to 80⁰C under argon for 8 hours. The reaction was allowed to cool and then added dropwise very cautiously to crushed ice (approximately 20Og). The aqueous mixture was then extracted with DCM (2x200ml_) and the combined extracts were washed with saturated sodium bicarbonate, dried over magnesium sulfate and evaporated to give a pale brown foam (8.7g).

A sample of crude 1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride (8g) prepared in a similar manner was taken up in DCM (2OmL) and split into 2 batches. The first batch was purified by flash chromatography on silica gel eluting with a solvent gradient of 0 to 30% ethyl acetate/hexane. Clean fractions were combined and concentrated in vacuo. The second batch was treated in the same way and the product was combined with that from the first batch to afford the title compound as a yellow solid.

¹H NMR (CDCI₃, 400MHz): δ 1.61-1.75 (2H, m), 1.93-2.02 (2H, m), 2.88 (1 H, t, J=13.0), 3.09 (2H, dt, J=8.5, 1.0), 3.27 (1 H, m), 3.52 (2H, dt, J=8.5, 1.5), 3.73 (1 H, tt, J=12.0, 4.0), 4.17 (1 H, m), 4.74 (1 H, m), 6.85 (1 H, d, J=2.0), 7.19 (1 H, dt, J=7.5, 1.0), 7.30 (1 H, dd, J=7.5, 2.0). Mass spectrum (ESI): Ci₅H₁₆CIF₃N₂O₃S requires 396/398; found 397/399 (MH⁺).

Intermediate 5

6-[(4,4-Difluoro-1 -piperidinyl)sulfonyl]-1 -[1 -(trifluoroacetyl)-4-piperidinyl]-2,3- dihydro-1H-indole

F

To a solution of 1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride (which may be prepared as described for Intermediate 4, 500mg, 1.36mmol) in DCM (1 OmL) was added triethylamine (0.44mL, 3.15mmol) and 4,4- difluoropiperidine hydrochloride (238mg, 1.5mmol). The mixture was stirred at room temperature under argon over the weekend. 1 M Aqueous HCI (1 OmL) was then added, the DCM layer was isolated using a phase separation cartridge and the solvent was removed in vacuo to afford the title compound as a yellow solid (537mg, 89%).

¹H NMR (CDCI₃, 400MHz): δ 1.59-1.77 (2H, m, partially masked by water peak), 1.90-1.99 (2H, m), 2.08 (4H, ddt, J=6.0, 6.0, 6.0), 2.86 (1 H, t, J=13.0), 3.05 (2H, dt, J=8.5, 1.0), 3.20 (4H, t, J=5.5), 3.25 (1 H, m), 3.48 (2H, dt, J=8.5, 1.5), 3.71 (1 H, tt, J=12.0, 4.0), 4.15 (1 H, m), 4.72 (1 H, m), 6.68 (1 H, d, J=1.5), 7.01 (1 H, dd, J=7.5, 1.5), 7.16 (1 H, dt, J=7.5, 1.0). Mass spectrum (ESI): C₂₀H₂₄F₅N₃O₃S requires 481 ; found 482 (MH⁺). Intermediate 5 (Alternative Procedure)

6-[(4,4-Difluoro-1 -piperidinyl)sulfonyl]-1 -[1 -(trifluoroacetyl)-4-piperidinyl]-2,3- dihydro-1H-indole The title compound was prepared in a manner analogous to the procedure described above except that the reaction time was reduced to 1 hour and the final compound was further purified by flash chromatography on silica gel (25+S, SP4) eluting with a solvent gradient of 0 to 50% ethyl acetate/hexane to afford the title compound as a yellow solid (165mg, 90%).

¹H NMR (CDCI₃, 400MHz): δ 1.61-1.74 (2H, m), 1.91-1.98 (2H, m), 2.02-2.14 (4H, m, partially obscured by EtOAc), 2.86 (1 H, t, J=13.0), 3.05 (2H, t, J=8.5), 3.20 (4H, t, J=5.5), 3.25 (1 H, m), 3.47 (2H, dt, J=8.5, 1.5), 3.70 (1 H, tt, J=12.0, 4.0), 4.15 (1 H, m, partially obscured by EtOAc), 4.72 (1 H, m), 6.66 (1 H, d, J=1.5), 7.00 (1 H, dd, J=7.5, 1.5), 7.15 (1 H, m).

Mass spectrum (ESI): C₂₀H₂₄F₅N₃O₃S requires 481 ; found 482 (MH⁺).

Intermediate 6

6-[(3,3-Difluoro-1 -piperidinyl)sulfonyl]-1 -[1 -(trifluoroacetyl)-4-piperidinyl]-2,3- dihydro-1H-indole

To a solution of 1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride (which may be prepared as described for Intermediate 4, 150mg, 0.38mmol) in DCM (1 OmL) was added triethylamine (132μl_, 0.95mmol) followed by 3,3- difluoropiperidine hydrochloride (71 mg, 0.45mmol). The mixture was stirred at room temperature under argon for 2 hours. It was then shaken with 1 M aqueous HCI (1OmL); the DCM layer was isolated and concentrated in vacuo. The resultant yellow oil was purified by flash chromatography on silica gel (25+S, SP4) eluting with a solvent gradient of 0 to 50% ethyl acetate/hexane to afford the title compound as a yellow oil (157mg, 86%).

¹H NMR (CDCI₃, 400MHz): δ 1.59-1.73 (2H, m, partially obscured by H₂O), 1.77-1.98 (6H, m), 2.88 (1 H, t, J=13.0), 3.01-3.12 (4H, m), 3.22-3.34 (3H, m), 3.41-3.51 (2H, m), 3.73 (1 H, tt, J=12.0, 4.0), 4.11-4.19 (1 H, m, partially obscured by EtOAc), 4.71 (1 H, m), 6.70 (1 H, d, J=1.5), 6.02 (1 H, dd, J=7.5, 1.5), 7.15 (1 H, m). Mass spectrum (ESI): C₂₀H₂₄F₅N₃O₃S requires 481 ; found 482 (MH⁺).

Intermediates 7-8

Intermediates 7-8 were prepared in a similar manner to Intermediate 5 from 1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 /-/-indole-6-sulfonyl chloride (which may be prepared as described for Intermediate 4) and the appropriate amine.

Intermediate 9

1,1-Dimethylethyl 3-(2,3-dihydro-1H-indol-1 -yl)-1-pyrrolidinecarboxylate

The title compound was prepared from indoline and 1-Boc-3-pyrrolidinone using a procedure similar to that described for 1 ,1-dimethylethyl 4-(2,3-dihydro-1 H-indol-1- yl)-1-piperidinecarboxylate (Intermediate 1 ).

¹H NMR (CDCI₃, 400MHz): δ 1.46 (9H, s), 2.00-2.18 (2H, m, partially obscured by EtOAc peak), 2.96 (2H, t, J=8.5), 3.29-3.45 (4H, m), 3.46-3.72 (2H, m), 4.02-4.18 (1 H, m, partially obscured by EtOAc peak), 6.49 (1 H, d, J=7.5), 6.67 (1 H, t, J=7.5), 7.02-7.1 1 (2H, m). Mass spectrum (ESI): C₁₇H₂₄N₂O₂ requires 288; found 289 (MH⁺).

Intermediate 10 1-[1-(Trifluoroacetyl)-3-pyrrolidinyl]-2,3-dihydro-1H-indole

To a solution of 1 ,1-dimethylethyl 3-(2,3-dihydro-1H-indol-1-yl)-1- pyrrolidinecarboxylate (which may be prepared as described for Intermediate 9, 1.55g, 5.39mmol) in methanol (1OmL) under argon was added 4M HCI/dioxan (1OmL). The mixture was stirred at room temperature for 1 hour then the reaction was concentrated in vacuo. The resultant residue was dissolved in DCM (1 OmL) and added to a solution of triethylamine (2.25mL, 16.17mmol) in DCM (15mL). After stirring for 10 minutes under argon trifluoroacetic anhydride (975μL, 7.00mmol) was added and stirring under argon at room temperature was continued for 3 hours. The reaction mixture was transferred to a separating funnel and washed with saturated aqueous sodium bicarbonate solution (2x30mL). It was then dried over sodium sulfate, filtered and concentrated in vacuo. The resultant brown oil was purified by flash chromatography on silica gel (FM2) eluting with a solvent gradient of 0 to 20% ethyl acetate/hexane to afford the title compound as a yellow oil (1.04g, 68%).

¹H NMR (CDCI₃, 400MHz): δ 2.10-2.35 (2H, m), 2.98 (2H, dt, J=8.5, 3.5), 3.32-3.43 (2H, t, J=8.0), 3.58-3.95 (4H, m), 4.21 (1 H, m), 6.49 (1 H, t, 7.5), 6.68-6.74 (1 H, ddt, J=7.5, 2.0, 1.0), 7.09 (2H, m). Mass spectrum (ESI): Ci₄H₁₅F₃N₂O requires 284; found 285 (MH⁺).

Intermediate 11 1-[1-(Trifluoroacetyl)-3-pyrrolidinyl]-2,3-dihydro-1H-indole-6-sulfonyl chloride

The title compound was prepared from 1-[1-(trifluoroacetyl)-3-pyrrolidinyl]-2,3- dihydro-1 H-indole (which may be prepared as described for Intermediate 10) in a similar fashion to the preparation of 1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro- 1H-indole-6-sulfonyl chloride (Intermediate 4).

¹H NMR (CDCI₃, 400MHz): δ 2.10-2.40 (2H, m), 3.12 (2H, ddt, J=9.0, 2.5, 1.0), 3.53- 3.60 (2H, m), 3.63-3.98 (4H, m), 4.32 (1 H, m), 6.93 (1 H, t, J=2.0), 7.23 (1 H, m), 7.36 (1 H, dt, J=7.5, 1.5). Mass spectrum (ESI): C₁₄H₁₄CIF₃N₂O₃S requires 382/4; found 383/385 (MH⁺).

Intermediate 12

6-[(3,3-Difluoro-1 -piperidinyl)sulfonyl]-1 -[1 -(trifluoroacetyl)-3-pyrrolidinyl]-2,3- dihydro-1H-indole

The title compound was prepared in a similar manner to 6-[(3,3-difluoro-1- piperidinyl)sulfonyl]-1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole (Intermediate 6) from 1 -[1 -(trifluoroacetyl)-3-pyrrolidinyl]-2,3-dihydro-1 H-indole-6- sulfonyl chloride (which may be prepared as described for Intermediate 11 ) and 3,3- difluoropiperidine.

¹H NMR (CDCI₃, 400MHz): δ 1.76-1.96 (4H, m), 2.08-2.37 (2H, m), 3.00-3.16 (4H, m), 3.19-3.37 (2H, m), 3.47-3.56 (2H, m), 3.62-3.95 (4H, m), 4.30 (1 H, m), 6.75 (1 H, dd, J=4.0, 1.5), 7.09 (1 H, ddd, J=7.5, 5.0, 1.5), 7.18 (1 H, m). Mass spectrum (ESI): Ci₉H₂₂F₅N₃O₃S requires 467; found 468 (MH⁺).

Example 1

6-[(3,3-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1H-indole hydrochloride (E1)

Step 1 : 6-[(3,3-Difluoro-1 -piperidinyl)sulfonyl]-1 -(4-piperidinyl)-2,3-dihydro-1H- indole

A solution of 6-[(3,3-difluoro-1-piperidinyl)sulfonyl]-1-[1-(trifluoroacetyl)-4-piperidinyl]- 2,3-dihydro-1 H-indole (Intermediate 6, 157mg, 0.33mmol) in 2M NH₃/MeOH (1 OmL) was stirred at room temperature for 2.5 hours. The solvent was removed in vacuo, the residue was dissolved in methanol and loaded onto an SCX cartridge which was then washed with methanol. The product was eluted using 2M NH₃/MeOH and the solvent was removed in vacuo to afford the title compound as a colourless paste (123mg, 97%).

¹H NMR (CDCI₃, 400MHz): δ 1.48-1.68 (2H, m, partially obscured by H₂O), 1.75-1.94 (6H, m), 2.73 (2H, dt, J=12.5, 2.5), 3.02 (2H, t, J=8.5), 3.06 (2H, t, J=5.5), 3.16-3.22 (2H, m), 3.26 (2H, t, J=11.0) 3.47 (1 H, m, partially obscured by MeOH), 3,51 (2H, t, J=8.5), 6.64 (1 H, d, J=1.5), 6.96 (1 H, dd, J=7.5, 1.5), 7.12 (1 H, m). Mass spectrum (ESI): C₁₈H₂₅F₂N₃O₂S requires 385; found 386 (MH⁺).

Step 2: 6-[(3,3-difluoro-1 -piperidinyl)sulfonyl]-1 -(4-piperidinyl)-2,3-dihydro-1 H- indole hydrochloride

6-[(3,3-difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 H-indole (which may be prepared as described for Example 1 , step 1 , 123mg, 0.32mmol) was dissolved in methanol and treated with 1 equivalent of 1 M HCI/Et₂O. The solvent was blown down and the resultant solid was dried in the vacuum oven to afford the title compound as a white solid (94mg, 70%).

¹H NMR (d⁶DMSO, 400MHz): δ 1.65-1.74 (2H, m), 1.75-2.01 (6H, m), 2.94-3.09 (6H, m), 3.23 (2H, t, J=11.5), 3.31-3.39 (2H, m), 3.44 (2H, t, J=8.5), 3.85-4.01 (1 H, m, partially obscured by H₂O), 6.79 (1 H, d, J=1.5), 6.93 (1 H, dd, J=7.5, 1.5), 7.20-7.27

(1 H, d, J=7.5), 8.83 (1 H, bm), 9.04 (1 H, bm).

Mass spectrum (ESI): Ci₈H₂₅F₂N₃O₂S requires 385; found 386 (MH⁺).

Example 2

6-[(4,4-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1H-indole hydrochloride (E2)

Step 1 : 6-[(4,4-Difluoro-1 -piperidinyl)sulfonyl]-1 -(4-piperidinyl)-2,3-dihydro-1H- indole

A solution of 6-[(4,4-difluoro-1-piperidinyl)sulfonyl]-1-[1-(trifluoroacetyl)-4-piperidinyl]- 2,3-dihydro-1 H-indole (Intermediate 5, 165mg, 0.34mmol) in 2M NH₃/MeOH was stirred at room temperature for 2.5 hours. The solvent was removed in vacuo, the residue was dissolved in methanol and loaded onto an SCX cartridge which was then washed with methanol. The product was eluted using 2M NH₃/MeOH and the solvent was removed in vacuo to afford the title compound as a colourless paste (118mg, 90%).

¹H NMR (CDCI₃, 400MHz): δ 1.61 (2H, ddt, J=12.0, 12.0, 4.0 partially obscured by H₂O peak), 1.74-1.83 (2H, m), 2.01-2.13 (4H, m), 2.72 (2H, t, J=12.5), 3.02 (2H, t, J=8.5), 3.19 (6H, t, J=5.5), 3.47 (1 H, m, partially obscured by MeOH), 3.52 (2H, t, J=8.5), 6.62 (1 H, d, J=1.5), 6.95 (1 H, dd, J=7.5, 1.5), 7.11 (1 H, d, J=7.5). Mass spectrum (ESI): C₁₈H₂₅F₂N₃O₂S requires 385; found 386 (MH⁺).

Step 2: 6-[(4,4-Difluoro-1 -piperidinyl)sulfonyl]-1 -(4-piperidinyl)-2,3-dihydro-1H- indole hydrochloride

6-[(4,4-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 H-indole (which may be prepared as described for Example 2, step 1 , 118mg, 0.31 mmol) was dissolved in methanol and treated with 1 equivalent of 1 M HCI/Et₂O. The solvent was blown down and the resultant solid was dried in the vacuum oven to afford the title compound as a white solid (130mg, 99%).

¹H NMR (d⁶DMSO, 400MHz): δ 1.74-1.94 (4H, m), 1.99-2.12 (4H, m), 2.97-3.09 (8H, m), 3.31-3.38 (2H, m), 3.44 (2H, t, J=8.5), 3.89 (1 H, tt, J=1 1.5, 4.0), 6.78 (1 H, d, J=1.5), 6.92 (1 H, dd, J=7.5, 1.5), 7.23 (1 H, m), 8.80 (1 H, bm), 9.05 (1 H, bm). Mass spectrum (ESI): Ci₈H₂₅F₂N₃O₂S requires 385; found 386 (MH⁺).

Example 3

1 -(4-Piperidinyl)-6-(1 -piperidinylsulfonyl)-2,3-dihydro-1 H-indole hydrochloride (E3)

1-[1-(Trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 /-/-indole-6-sulfonyl chloride (which may be prepared as described for Intermediate 4) (0.5g, 1.27mmol) was taken up in DCM (8ml_) and piperidine (107.9mg, 1.27mmol) was added. After 10 minutes the mixture was evaporated and the crude product (700mg) was taken up in ethanol (2OmL) and 3M NaOH (15ml_) was added. The mixture was left to stir for 1 hour. LC/MS confirmed that the reaction was complete. The mixture was evaporated, then taken up in DCM and washed with brine. The organic layer was collected and evaporated and the crude product (163mg) was purified by column chromatography eluting with 0-10% [2M NH₃/MeOH] in DCM. Pure fractions were evaporated, taken up into methanol and HCI in ether was added. The title hydrochloride salt was obtained as an off-white solid (55mg) after evaporation from acetone.

¹H NMR (d⁶DMSO, 400MHz): 1.32-1.40 (2H, m), 1.49-1.57 (4H, m), 1.76-1.90 (4H, m), 2.85 (4H, t, J=5.5), 2.97-3.10 (4H, m), 3.36 (2H, m), 3.44 (2H, t, J=8.5), 3.88 (1 H, m), 6.72 (1 H ,d, J=1.5), 6.88 (1 H, dd, J=7.5, 1.5), 7.21 (1 H, d, J=7.5). Mass spectrum (ESI): Ci₈H₂₇N₃O₂S requires 349; found 350 (MH⁺).

Example 3A 1 -(4-Piperidinyl)-6-(1 -piperidinylsulfonyl)-2,3-dihydro-1 H-indole (E3A)

Step 1 : 6-(1 -Piperidinylsulfonyl)-1 -[1 -(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro- 1H-indole

1-[1-(Trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride (which may be prepared as described for Intermediate 4, 500mg, 1.26mmol) in dry DCM (2OmL) was treated with triethylamine (193μL, 1.37mmol) and piperidine (112mg, 1.32mmol) (as a solution in 2mL dry DCM). The reaction was stirred at room temperature overnight. It was then washed with water (3OmL), the DCM layer was isolated and concentrated in vacuo. The resultant oil was further purified by flash chromatography on silica gel (25+M, SP4) eluting with a solvent gradient of 0 to 30% ethyl acetate/hexane to afford the title compound as an oil (350mg, 62%).

¹H NMR (d⁶DMSO, 400MHz): δ 1.32-1.40 (2H, m), 1.49-1.64 (6H, m), 1.76-1.86 (2H, m), 2.85 (4H, t, J=5.5), 2.97 (2H, t, J=8.5), 2.99-3.08 (1 H, m), 3.38-3.47 (1 H, m), 3.36 (2H, t, J=8.5), 3.88-3.99 (2H, m), 4.42 (1 H, m), 6.71 (1 H, d, J=1.5), 6.86 (1 H, dd, J=7.5, 1.5), 7.20 (1 H, d, J=7.5).

Mass spectrum (ESI): C₂₀H₂₆F₃N₃O₃S requires 445; found 446 (MH⁺).

Step 2: 1 -(4-Piperidinyl)-6-(1 -piperidinylsulfonyl)-2,3-dihydro-1 H-indole

6-(1-Piperidinylsulfonyl)-1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole (which may be prepared as described for Step 1 above) (350mg, 0.79mmol) was dissolved in dry methanol (3OmL) and treated with 2M NH₃/MeOH (1 OmL). The reaction was allowed to stand at room temperature overnight then concentrated in vacuo. The residue was purified by flash chromatography on silica gel (25+M, SP4) eluting with a solvent gradient of 0 to 30% methanol/dichloromethane to afford the title compound as a clear oil (258mg, 94%).

¹H NMR (d⁶DMSO, 400MHz): δ 1.32-1.40 (2H, m), 1.49-1.70 (8H, m), 2.71 (2H, dt, J=12.0, 2.5), 2.85 (4H, t, J=5.5), 2.98 (2H, t, J=8.5), 3.08-3.14 (2H, m), 3.44 (2H, t, J=8.5, partially obscured by H₂O peak), 3.61 (1 H, tt, J=11.5, 4.0), 6.62 (1 H, d, J=1.5), 6.84 (1 H, dd, J=7.5, 1.5), 7.19 (1 H, d, J=7.5).

Mass spectrum (ESI): Ci₈H₂₇N₃O₂S requires 349; found 350 (MH⁺).

Example 4

1 -(4-Piperidinyl)-6-(tetrahydro-1 ,4-oxazepin-4(5H)-ylsulfonyl)-2,3-dihydro-1 H- indole hydrochloride (E4)

The title compound was prepared in a similar manner to Example 1 from Intermediate 8.

¹H NMR (d⁶DMSO, 400MHz): δ 1.69-1.80 (6H, m), 2.88-2.97 (2H, m), 2.98 (2H, t,

J=8.5), 3.23-3.31 (6H, m, partially obscured by H₂O peak), 3.43 (2H, t, J=8.5), 3.60-

3.65 (4H, m), 3.79 (1 H, m), 6.76 (1 H, d, J=1.5), 6.93 (1 H, dd, J=7.5, 1.5), 7.71-7.19

(1 H, d, 7.5).

Mass spectrum (ESI): Ci₈H₂₇N₃O₃S requires 365; found 366 (MH⁺).

Example 5

6-[(4-Fluoro-1-piperidinyl)sulfonyl]-1 -(4-piperidinyl)-2,3-dihydro-1H-indole hydrochloride (E5)

The title compound was prepared in a similar manner to Example 1 from

Intermediate 7 with the exception that in step 1 purification by MDAP was used instead of SCX.

¹H NMR (d⁶DMSO, 400MHz) δ 1.71-1.97 (8H, m), 2.85-2.93 (2H, m), 2.96-3.10 (6H, m), 3.31-3.39 (2H, m), 3.44 (2H, t, J=8.5), 3.89 (1 H, tt, J=1 1.5, 4.0), 4.75 (1 H, m, partially obscured by H₂O peak), 6.75 (1 H, d, J=1.5), 6.90 (1 H, dd, J=7.5, 1.5), 7.22 (1 H, d, J=7.5), 8.83 (1 H, bm), 9.06 (1 H, bm). Mass spectrum (ESI): Ci₈H₂₆FN₃O₂S requires 367 ; found 368 (MH⁺). Example 6

1 -(4-Piperidinyl)-6-(1 -pyrrolidinylsulfonyl)-2,3-dihydro-1 H-indole hydrochloride

Pyrrolidine (108mg, 1.52mmol) was added to a stirred solution of 1-[1- (trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride (which may be prepared as described for Intermediate 4) (300mg, 0.76mmol) in DCM (5ml_). The reaction was stirred for 2 hours and the DCM was then evaporated. Potassium carbonate (315mg, 2.28mmol) dissolved in water (2ml_) was added to the crude residue in MeOH (5ml_). The reaction was stirred at room temperature for 3h then evaporated in vacuo. The residue was dissolved in a minimum volume (<5ml_) of saturated NaHCC>3 solution and extracted with DCM (3x 5OmL). The extracts were dried, evaporated and the residue was purified by flash chromatography on silica (10% 2M NH3/MeOH) in DCM. The free base was triturated with ether then converted into the HCI salt by dissolving in DCM and treating with excess 1 M HCI in ether. After evaporation of solvents the residue was dried to give the title compound as a white solid (95mg).

¹H NMR (d⁶DMSO, 400MHz) δ 1.63 (4H, m), 1.71-1.93 (4H, m), 2.96-3.08 (4H, m), 3.12 (4H, m), 3.30-3.40 (2H, m), 3.43 (2H, t, J=8.5), 3.91 (1 H, m), 6.81 (1 H, m, J=1.5), 6.96 (1 H, dd, J=7.5, 1.5), 7.21 (1 H, d, J=7.5), 8.73 (1 H, bm), 8.93 (1 H, bm). Mass spectrum (ESI): C₁₇H₂₅N₃O₂S requires 335 ; found 336 (MH⁺)

Example 7

6-(Hexahydro-1 H-azepin-1 -ylsulfonyl)-1 -(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E7)

Homopiperidine (187mg, 1.89mmol) was taken up in DCM (7m L) and triethylamine (0.26mL, 1.89mmol) was added. This was left to stir for 5 minutes then 1-[1-

(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride (which may be prepared as described for Intermediate 4) (300mg, 0.76mmol) was added and the mixture was left to stir overnight. LC/MS confirmed that the reaction was complete. The mixture was evaporated and the crude product was deprotected in MeOH (16mL) by treatment with potassium carbonate (500mg in 2mL MeOH). The mixture was allowed to stir for 2 hours, then evaporated, diluted with DCM and a few mL bicarbonate solution was added. This was extracted with DCM ( 3x). The organic layers were dried over magnesium sulfate, filtered and evaporated. The residue was taken up into DCM and purified by column chromatography. The product was eluted with 10% 2M NH3/MeOH in DCM. Pure fractions were collected and the free base product was taken up in MeOH and treated with HCI in ether to give the HCI salt as a white solid (67mg).

¹H NMR (d⁶DMSO, 400MHz) δ 1.49 (4H, m), 1.61 (4H, m), 1.72-1.91 (4H, m), 2.93- 3.11 (4H, m), 3.17 (4H, t, J=6.0), 3.35 (2H, d, J=12.5), 3.42 (2H, t, J=8.5), 3.89 (1 H, m), 6.79 (1 H, d, J=1.5), 6.92 (1 H, dd, J=7.5, 1.5), 7.18 (1 H, d, J=7.5), 8.73 (1 H, bm), 8.96 (1 H, bm).Mass spectrum (ESI): C₁₉H₂₉N₃O₂S requires 363 ; found 364 (MH⁺).

Example 8

6-(4-Morpholinylsulfonyl)-1 -(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride

The title compound was prepared in a similar manner to Example 6 from morpholine and 1-[1-(trifluoroacetyl)-4-piperidinyl]-2,3-dihydro-1 H-indole-6-sulfonyl chloride (which may be prepared as described for Intermediate 4).

¹H NMR (d⁶DMSO, 400MHz) δ 1.76-1.92 (4H, m), 2.84 (4H, m), 3.02 (4H, m), 3.31- 3.41 (2H, m), 3.45 (2H, t, J=8.5), 3.62 (4H, t, J=4.5), 3.89 (1 H, m), 6.73 (1 H, d, J=1.5), 6.89 (1 H, dd, J=7.5, 1.5), 7.24 (1 H, d, J=7.5), 8.73 (1 H, bm), 8.97 (1 H, bm). Mass spectrum (ESI): C₁₇H₂₅N₃O₃S requires 351 ; found 352 (MH⁺)

Example 9

1 -(1 -Ethyl -4-piperidinyl)-6-(1 -piperidinylsulfonyl)-2,3-dihydro-1 H-indole (E9)

1-(4-Piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole (which may be prepared as described for Example 3A, 190mg, 0.54mmol) was dissolved in DCM (1 OmL) and acetaldehyde (119mg, 2.70mmol) was added followed by sodium triacetoxyborohydride (286mg, 1.36mmol) portionwise. The reaction was left standing at room temperature for 3 days. The reaction was then quenched with methanol (0.5ml), diluted with DCM (30ml) and washed with 2N sodium hydroxide (2OmL). The DCM layer was dried over magnesium sulfate, filtered and concentrated in vacuo. The resultant orange oil was purified by flash chromatography on silica gel (12+M, SP4) eluting with a solvent gradient of 0 to 40% methanol/dichloromethane to afford the title compound as a beige solid (69mg, 34%).

¹H NMR (d⁶DMSO, 400MHz): δ 1.00 (3H, t, J=7.0), 1.31-1.39 (2H, m), 1.48-1.56 (4H, m), 1.59-1.68 (4H, m), 2.84, (4H, t, J=5.5), 2.97 (4H, t, J=8.5), 3.30-3.37 (4H, m, partially obscured by H₂O peak), 3.45 (3H, m), 6.58 (1 H, d, J=1.5), 6.83 (1 H, dd, J=7.5, 1.5), 7.18 (1 H, d, J=7.5). Mass spectrum (ESI): C₂₀H_3IN₃O₂S requires 377; found 378 (MH⁺).

Example 10

6-[(3,3-Difluoro-1 -piperidinyl)sulfonyl]-1 -(3-pyrrolidinyl)-2,3-dihydro-1 H-indole hydrochloride (E10)

The title compound was made from 6-[(3,3-difluoro-1-piperidinyl)sulfonyl]-1-[1- (trifluoroacetyl)-3-pyrrolidinyl]-2,3-dihydro-1 H-indole (which may be prepared as described for Intermediate 12) in a similar manner to the preparation of 6-[(3,3- difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (Example 1 , steps 1 and 2).

¹H NMR (d⁶DMSO, 400MHz): δ 1.65-1.74 (2H, m), 1.88-2.05 (3H, m), 2.09-2.19 (1 H, m), 2.95-3.05 (4H, m), 3.07-3.27 (4H, m), 3.28-3.44 (2H, m), 3.52 (2H, dt, J=8.5, 5.5), 4.52 (1 H, m), 6.79 (1 H, d, J=1.5), 6.99 (1 H, dd, J=7.5, 1.5), 7.26 (1 H, d, J=7.5), 9.23 (1 H, bm), 9.46 (1 H, bm). Mass spectrum (ESI): Ci₇H₂₃F₂N₃O₂S requires 371 ; found 372 (MH⁺).

Purification Methods

Flash column chromatography was carried out using either: Jones Flashmaster 2; Biotage SP4 system using standard Biotage cartridges [12+S, 12+M, 25+S, 25+M, 40+S, 40+M, 65+M(65i)]; or lsco Combiflash Companion XL.

Where indicated, Varian Mega BE (10g, 5Og) SCX columns or lsolute Flash SCX-2 (2Og) columns were used in the work-up of reactions. Crude mixtures were applied to the column, non-polar materials were washed off with methanol, and the desired amines were eluted with ammonia in methanol.

Phase separation cartridges were supplied by lsolute. Mass Directed Auto-Purification (MDAP) was carried out using a purification system supplied by Waters. The columns used were Waters Atlantis (19mm x 100mm or 30mm x 100mm). The solvent systems used comprised solvent A (water + 0.1% formic acid) and solvent B (acetonitrile + 0.1 % formic acid) with gradients within the range 5-99% solvent B in solvent A.

Analytical Equipment

¹H NMR spectra were recorded using the following: Hardware - Bruker Avance 400 Ultrashield 400MHz spectrometer

- Bruker Avance DPX400 console

- Bruker 250MHz spectrometer

- Bruker Avance DPX250 console

- Bruker B-ACS 60 autosampler Software - User interface: NMR-Kiosk

- Controlling software: Xwin NMR v3.0 or Bruker Topspin v1.3

Chemical shifts are expressed in parts per million (ppm, δ units). Coupling constants (J) are in units of hertz (Hz). Splitting patterns describe apparent multiplicities and are designated as s (singlet), d (doublet), t (triplet), q (quartet), dd (double doublet), dt (double triplet), tt (triple triplet), m (multiplet), b (broad).

Analytical LC/MS analysis was carried out using the following equipment:

Agilent 1100 Gradient Pump

Agilent 1100 Autosampler

Agilent 1100 DAD Detector

Agilent 1100 Degasser

Agilent 1100 Oven Agilent 1100 Controller

Waters ZQ Mass Spectrometer

Sedere Sedex 75 Software : Waters MassLynx version 4.0 SP2

Column :_The column used is a Waters Atlantis, the dimensions of which are 4.6mm x 50mm. The stationary phase particle size is 3μm.

Solvents :

A : Aqueous solvent = Water + 0.05% Formic Acid B : Organic solvent = Acetonitrile + 0.05% Formic Acid

Method

The generic method used has a 5 minute runtime.

Or alternatively:

Waters Acquity Binary Solvent Manager Waters Acquity Sample Manager Waters Acquity PDA Detector Waters Acquity Degasser Waters Acquity Oven Waters Acquity Controller Waters ZQ Mass Spectrometer Sedere Sedex 85

Software : Waters MassLynx version 4.0 SP2

Column : The column used is a Acquity UPLC BEH, the dimensions of which are 2.1 mm x 50mm. The stationary phase particle size is 1.7μm.

Solvents

A : Aqueous solvent = Water + 0.05% Formic Acid

B : Organic solvent = Acetonitrile + 0.05% Formic Acid

Method

The generic method used has a 2 minute runtime.

Mass spectra were performed under electrospray ionisation (ESI).

Pharmacological data Compounds of the invention may be tested for in vitro biological activity at the 5- HT_2A, 5-HT_2B, 5-HT_2C and 5-HT₆ receptors in accordance with the following studies:

5-HTfi membrane preparation This method covers the generation of membranes from HEK cells transduced with Bacmam 5-HT₆.

All steps were performed at 4°C. Cells were homogenised within a glass Waring blender for 2 bursts of 15 sees in 20OmIs of buffer (5OmM HEPES, 1 mM leupeptin, 25μg/ml bacitracin, 1 mM EDTA, 1 mM PMSF, 2μM pepstatin A). The blender was plunged into ice for 5 mins after the first burst and 10-40 mins after the final burst to allow foam to dissipate. The material was then spun at 50Og for 20 mins and the supernatant spun for 36 mins at 48,00Og. The pellet was resuspended in the same buffer as above but without PMSF and pepstatin A. The material was then forced through a 0.6mm needle, made up to the required volume, (usually x4 the volume of the original cell pellet), aliquoted and stored frozen at -80⁰C.

5-HTR_ antagonist assay

The potency of test compounds was determined using a HitHunter DiscoverX cAMP assay. The HitHunter DiscoveRx cAMP assay uses a split enzyme complementation readout to capture the content of cAMP either in whole cells or generated from cell membranes. The split enzyme used in the assay is β-galactosidase which is measured using a luminescence readout.

Briefly, HEK membranes expressing 5-HT₆ (6μg/well) were resuspended in assay buffer, containing 5OmM HEPES pH 7.4 (KOH), 1OmM MgCI₂, 10OmM NaCI, 10μM IBMX and added to a white Greiner polypropylene 384-well plate (1 Oμl/well), containing 0.5μl of test compound. The plate was incubated for 30min at room temperature before ATP buffer (basic buffer plus 3mM ATP) containing 2 X EC₈O of the agonist 5-HT was added (1 Oμl). Plates were incubated for 30-45min before the cAMP content was measured as per the HitHunter DiscoveRx kit instructions. Basically the cells were lysed and an antibody to cAMP added along with the two fragments of β-gal one linked to cAMP (enzyme donor) and one to enzyme acceptor to form active enzyme. The substrate is hydrolysed by the active enzyme for EFC detection (luminescence) of β-gal activity. The final assay cocktail (60.5μl) was incubated at room temperature to equilibrate for 3 hrs before reading on a Viewlux.

Test compounds were dissolved in DMSO at a concentration of 1 OmM and were prepared in 100% DMSO using a 1 in 4 dilution step to provide 1 1 point dose response curves. The dilutions were transferred to the assay plates ensuring that the DMSO concentration was constant across the plate.

All data was normalized to the mean of 16 high and 16 low control wells on each plate. A four parameter curve fit of the following form was then applied.

Where a is the minimum, b is the Hill slope, c is the XC₅₀ and d is the maximum. Data is presented as the mean pXC₅o (negative Iog10 of the molar XC₅o) with the standard deviation (SD) of n experiments.

K| and functional K, values were calculated using the method of Cheng, Y.C. and Prussof, W. H. (Biochemical Pharmacol (1973) 22 3099-3108). For functional data a modified form of the equation is used where the K_d is replaced by the EC₅₀ of the assay agonist and concentration of the radioligand was substituted with the concentration of the added agonist. The equation is shown below where L is the ligand concentration and K_d is the affinity of the ligand for the receptor.

K, = ^■'so

1 + [L

K,

Cell culture

Adherent SH-SY5Y cells stably expressing the recombinant human 5-HT_2A, 5-HT_2B or 5-HT_2C were maintained in culture at 37°C under 5% CO₂ in Dulbecco's Modification of Eagle's Medium supplemented with 10% dialysed foetal calf serum and 400 micrograms geneticin. The cloning of human 5-HT_2A and 5-HT_2C receptors (previously denoted as 5-HT₂ and 5-HT_1c receptors respectively) is described by Saltzman et al., Biochemical and Biophysical Research Communications (1991 ) Vol.181 No.3, 1469- 1478. The cloning of the human 5-HT₂₆ receptors is described by Schmuck et al., FEBS Letters (1994) Vol.342, 85-90. SH-SY5Y cells are commercially available from the American Type Culture Collection (ATCC), catalogue number CRL-2266.

Measurement of [CaI using the FLIPR

SH-SY5Y cells, separately expressing 5-HT_2A , 5-HT_2B or 5-HT_2C receptors, were seeded into black walled clear-base 384-well plates at a density of 16,000 cells per well and cultured overnight at 37°C under 5% CO₂. Media was aspirated off and cells were then incubated with Tyrode's medium (in mM; NaCI 145, KCI 2.5, HEPES 10, Glucose 10, MgCI₂ 1.2, CaCI₂ 1.5) containing the cytoplasmic calcium indicator, Fluo- 4 in the acetylmethyl form (4 mM) and 250μM Brilliant Black (Molecular Devices) at 37°C for 60 min. The loaded cells were then incubated for 30 min at 37°C with either buffer (agonist mode) or compound (antagonist mode). The plates were then placed into a FLIPR (Molecular Devices, UK) to monitor cell fluorescence (λex 488nm, λem 540nm) before and after the addition of various compounds (in agonist mode) or a pre-determined concentration of 5-HT (approximately 4xEC50) for testing in antagonist mode. Functional Ki values were calculated from IC50 values in accordance with the following equation:

fKi = IC50

1 + agonist cone (M) EC50

The functional pKi (fpKi) values can then be calculated from the negative Iog10 of the fKi values.

The compounds of Examples 1-10 were tested in certain of the above assays and found to have the fpKi values shown in the following table:

Examples 1 -10 were also tested in the 5HT_2A and 5HT₂c assays and displayed fpKi values of < 5.8 and < 6.7 respectively.

Abbreviations

1 ,2-DCE 1 ,2-dichloroethane dioxan 1 ,4-dioxane

DCM dichloromethane

DMSO dimethylsulfoxide

THF tetrahydrofuran

SCX strong cation exchange Note: 2M NH3/MeOH refers to a solution of ammonia in methanol supplied by ROMIL.

Claims

Claims

1. A compound of formula (I), or a pharmaceutically acceptable salt thereof:

(I) wherein:

R¹ represents a nitrogen containing heterocyclyl group selected from pyrrolidinyl, piperidinyl, morpholinyl, hexahydro-1 ,4-oxazepine or hexahydro-1H-azepine, wherein the nitrogen atom of the nitrogen containing heterocyclyl group is linked to the sulfur atom of the SO₂ moiety, and wherein each of said heterocyclyl groups may be optionally substituted by one or more (e.g. 1 , 2 or 3) fluorine atoms; n represents an integer selected from 1 or 2; and

R² represents hydrogen or C_1-3 alkyl.

2. A compound according to claim 1 which is

6-[(3,3-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E1 );

6-[(4,4-Difluoro-1-piperidinyl)sulfonyl]-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E2);

1-(4-Piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole hydrochloride (E3);

1-(4-Piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole (E3A);

1-(4-Piperidinyl)-6-(tetrahydro-1 ,4-oxazepin-4(5H)-ylsulfonyl)-2,3-dihydro-1 /-/-indole hydrochloride (E4); 6-[(4-Fluoro-1 -piperidinyl)sulfonyl]-1 -(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E5);

1-(4-Piperidinyl)-6-(1-pyrrolidinylsulfonyl)-2,3-dihydro-1 H-indole hydrochloride (E6);

6-(Hexahydro-1 H-azepin-1-ylsulfonyl)-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E7); 6-(4-Morpholinylsulfonyl)-1-(4-piperidinyl)-2,3-dihydro-1 H-indole hydrochloride (E8);

1-(1-Ethyl-4-piperidinyl)-6-(1-piperidinylsulfonyl)-2,3-dihydro-1 H-indole (E9); or

6-[(3,3-Difluoro-1-piperidinyl)sulfonyl]-1-(3-pyrrolidinyl)-2,3-dihydro-1 H-indole hydrochloride (E10).

3. A pharmaceutical composition which comprises the compound of formula (I) as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier or excipient.

4. A compound as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof for use in therapy.

5. A compound as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof for use in the treatment of fibrosis or a fibrotic condition, IBS, inflammatory pain, visceral pain, migraine or pulmonary arterial hypertension.

6. A compound as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof for use in the treatment of fibrosis or a fibrotic condition.

7. Use of a compound as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for the treatment of fibrosis or a fibrotic condition, IBS, inflammatory pain, visceral pain, migraine or pulmonary arterial hypertension.

8. Use of a compound as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for the treatment of fibrosis or a fibrotic condition.

9. A method of treatment of fibrosis or a fibrotic condition, IBS, inflammatory pain, visceral pain, migraine or pulmonary arterial hypertension which comprises administering to a mammal in need of said treatment an effective amount of a compound of formula (I) as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof.

10. A method of treatment of fibrosis or a fibrotic condition which comprises administering to a mammal in need of said treatment an effective amount of a compound of formula (I) as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof.

11. A pharmaceutical composition for use in the treatment of fibrosis or a fibrotic condition, IBS, inflammatory pain, visceral pain, migraine or pulmonary arterial hypertension which comprises the compound of formula (I) as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier.

12. A pharmaceutical composition for use in the treatment of fibrosis or a fibrotic condition which comprises the compound of formula (I) as defined in claim 1 or claim 2 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier.