Inflammatory Bowel Disease (IBD), which includes ulcerative colitis (UC) and Crohn’s disease (CD), is a multifactorial disease of an etiology not fully understood. It includes chronic inflammation of the gut, characterized by dysfunction of mucosal immunity. Current oral therapies are ineffective, non-specific, and have significant adverse effects. As such, there is a large unmet medical need for the development of new and specific therapies for IBD.

Adenosine is a stimulator of pro-inflammatory effects in the gastro-intestinal tract. Adenosine regulates tissue function by activating its receptors: A₁AdoR and A_2AAdoR are high affinity receptors and A_2BAdoR and A₃AdoR are low affinity receptors. A_2BAdoR is highly expressed in cecum and colon, with expression increased even further in epithelial cells in human and murine colitis. A_2BAdoR, agonized by adenosine induces cytokine secretion at the mucosal surface, inflammatory cell infiltration into intestinal wall, focal crypt damage and ulceration. Therefore, A_2BAdoR antagonists are expected to be beneficial in IBD patients.

PNQ-201 is a proprietary orally active A_2BAdoR antagonist, currently in pre-clinical development for the potential treatment of IBD. PNQ-201 is a potent and selective A2B antagonist. It is selected for development on the basis of poor systemic bioavailability and high exposure in colon/cecum. Negligible systemic bioavailability and maximum exposure at the sites of action in the lower gastrointestinal tract is expected to offer maximum therapeutic benefits while minimizing potential side effects. PNQ-201 has shown a robust efficacy profile in standard models of IBD, namely, the mouse DSS-induced colitis model and the rat TNBS-induced colitis model. PNQ-201 was found to be safe in exploratory safety studies including a Drug Matrix Screen, mini-AMES test, and a 14- day repeat dose toxicology study in rats.

PATENT

https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2010103547&recNum=198&docAn=IN2010000145&queryString=(FP/Atherosclerosis)%20&maxRec=2268

Example 1 : 8-(l-Benzyl~lH-pyrazol-4-yl)-l-propyl-l,4,5,7-tetrahydro-purin-6-one

Step 1: l-Benzyl-lH-pyrazole-4-carboxylic acid (6-amino-2,4-dioxo-3-propyl-l,2,3,4-tetrahydro-pyrimidin-5-yl)-amide

A mixture of 5,6-diamino-3-propyl-lH-pyrimidine-2,4-dione (1.6g, 8.55mmol), 1-benzyl-lH-pyrazole-4-carboxylic acid (1.75g, 8.65mmol) in methanol (10ml) were cooled to 0 ⁰C and added EDCLHCl (2.32g, 12.11mmol). The reaction mixture was stirred at 25 ⁰C for 20 hours and the solvents were removed under reduced pressure. To this residue water (10ml) was added and the precipitate was filtered off, and was washed sequentially with cold water (20ml) and DCM (25ml) to obtain l-Benzyl-lH-pyrazole-4-carboxylic acid (6-amino-2,4-dioxo-3 -propyl- 1 ,2,3,4-tetrahydro-pyrimidin-5-yl)-amide (1.5 g, 47 %) as a pale yellow solid.

¹HNMR^OOMHZ₅ DMSO d6): δ 0.82 (t, J=7.6Hz_s 3H); 1.46-1.51 (m, 2H); 3.64 (t, J=7.2Hz, 2H);^5.36 (s, 2H); 6.01 (s, 2H); 7.26-7.38 (m, 5H); 7.96 (s, IH); 8.31 (s, IH); 8.54 (s, IH); 10.43 (s, IH).

Step 2 : 8-(l-Benzyl-lH-pyrazol-4-yl)-2-chloro-l-propyH,7-dihydro-purin-6-one A mixture of l-benzyl-lH-pyrazole-4-carboxylicacid(6-amino-2,4-dioxo-3-propyl-l,2,3,4-tetrahydro-ρyrimidin-5-yl)-amide (0.5g, 13.5mmol)_s POCl₃ (10ml) and DMF (0.1ml) were heated at 125-130 ⁰C for 20 hours. Reaction mixture was cooled to 20-25 ⁰C. It was then concentrated under vacuum. The residue was triturated with diethyl ether, dried. The crude product was purified by column chromatography using silica gel (100-200 mesh) and 2 to 4 % methanol in DCM as an eluent to obtain 8-( 1 -Benzyl- 1 H-pyrazol-4-yl)-2-chloro-l -propyl- l,7-dihydro-purin-6-one (0.04g, 8%) as a pale brown solid.

¹HNMR^OOMHZ₅ DMSO d6): δ 0.93 (t, J=7.6Hz, 3H); 1.67-1.73 (m, 2H); 4.15 (t, J=7.6Hz, 2H); 5.42 (s, 2H); 7.29-7.39 (m, 5H); 8.14 (s, IH); 8.49 (s, IH); 13.68 (bs, IH). Step 3: 8-(l-Benzyl-lH-pyrazol-4-yl)-l-propyl-l,7-dihydro-purin-6-one

A mixture of 8-(l -benzyl- lH-pyrazol-4-yl)-2-chloro-l -propyl- l,7-dihydro-purin-6-one (0.035 g, 0.094 mmol), Pd\C (10%) (0.025g), in ethanol (20ml) were stirred under hydrogen atmosphere for 20 hours. Reaction mixture was filtered through celite bed washed with methanol (20ml), and the solvents were removed under vacuum. The crude product was purified by column chromatography using silica gel (100-200 mesh) and 2 to 4 % methanol in DCM as an eluent to obtain 8-(l-Benzyl-lH-pyrazol-4-yl)-l-propyl-l,7-dihydro-purin-6-one (0.012g, 39%) as off white solid.

¹HNMR^OOMHZ, DMSO d6): δ 0.89 (t, J=7.2Hz, 3H); 1.66-1.72 (m, 2H); 3.94 (t, J=7.6Hz, 2H); 5.41 (s, 2H); 7.302-7.38 (m, 5H); 8.03 (s, IH); 8.16 (s, IH); 8.34 (s, IH).

PATENT

WO 2011055391

https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2011055391

Preparation 1: 2-chloro-8-cyclopentyl-l-propyI-l, 7-dihydro-purin-6-one:

Step 1: Cyclopentane carboxylic acid (6-amino-2,4-dioxo-3-propyl-l,2,3,4-tetra hydro-pyriniidin-S-y -amide

To a solution of 5, 6-diamino-3-propyI-lH-pyrimidine-2, 4-dione (0.6 g, 2.72 mmol) in methanol (50 ml) was added cyclopentane carboxylic acid (0.310 g, 2.72 mmol). The reaction mixture was cooled to 0°C and then l-ethyl-3(3′-dimethylaminopropyl) carbodiimide hydrochloride (EDCI.HC1) (0.78 g, 4.1 mmol) was added. The resulting reaction mixture was stirred at room temperature overnight. The reaction mixture was concentrated under reduced pressure. The residue was dissolved in water. The solid was filtered and washed thoroughly with water followed by diethyl ether. The product obtained was dried under high vacuum. The crude product (0.40 g) was used for the next step without further purification.

Step 2: Preparation of 8-cyclopentyI-2-chloro-l-propyl-l, 7-dihydro-purin-6-one

To a suspension of cyclopentanecarboxylic acid (6-amino-2,4-dioxo-3-propyl- 1,2,3,4-tetrahydro-pyrimidin-5-yl)-amide (0.40 g, crude) obtained from step 1 in phosphorus oxychloride (25 ml) was added phosphorus pentachloride (0.10 g) and the resulting reaction mixture was refluxed overnight. Phosphorus oxychloride was evaporated under reduced pressure. The residue was slowly quenched with water. Ethyl acetate was added and the organic layer was separated and washed thoroughly with water followed by brine. The ethyl acetate layer was dried over anhydrous sodium sulphate and concentrated under vacuum. The crude product was purified by preparative TLC using dichloromethane, methanol (9:1) as the solvent system to give 0.075 g (19% over two steps) of the product as a white solid.

•H MR (400 MHz, DMSO d6): δ 0.9 (t, J = 8 Hz, 3H), 1.59-1.82 (m, 8H), 1.99 (m, 2H), 3.15 (t, J = 8 Hz, 1H), 4.12 (t, J = 8 Hz, 2H).

Preparations 2 to 7 were prepared following the experimental procedure as given for Preparation 1.

Preparation 2: 2-Chloro-8-cyclohexyl- 1 -propyl- 1 ,7-dihydro-purin-6-one,

Preparation 3: 2-Chloro-8-cyclopropyl-l -propyl- 1 ,7-dihydro-purin-6-one,

Preparation^ 2-Chloro-8-(hexahydro-2,5-methano-pentalen-3a-yl)-l -propyl- 1,7- dihydro-purin-6-one,

Preparation 5: 8-Bicyclo-[2.2.1]-hept-2-yl-2-chloro-l -propyl- 1, 7-dihydro-purin-6- one,

Preparation 6: 8-Adamantan-2-yl-2-chloro-l -propyl- 1, 7-dihydro-purin-6-one, Preparation7:3-[4-(2-Chloro-6-ox0-l-propyl-6,7-dihydro-lH-purin-8-yl)- bicyclo[2.2.2]oct-l-yl]-propionic acid.

Example 1: 8-Cyclopentyl-2-(3, 4-difluoro-phenoxy)-l-propyl-l, 7-dihydro-purin- 6-one:

To a solution of 8-cyclopentyl-2-chloro- 1 -propyl- l,7-dihydro-purin-6-one (0.06 g, 0.21 mmol) in N-methyl-2-pyrrolidone (0.2 ml) was added K2CO3 (0.044g, 0.32 mmol) followed by 3, 4-difluoro phenol and the reaction mixture was heated at 130 °C overnight. The reaction mixture was diluted with ethyl acetate and water. The layers were separated and ethyl acetate layer was washed with water. The ethyl acetate layer was dried over anhydrous sodium sulphate and concentrated under vacuum. The crude product was purified by preparative TLC using 3% methanol in DCM to give the product (0.015 g, 19 %) as a white solid.

‘HNMR (400 MHz, DMSO d6): δ 0.94 (t, J = 8 Hz, 3H), 1.59-1.74 (m, 6H), 1.94 (br.s, 2H), 3.12 (m, 2H), 4.09 (br. s, 2H), 7.21 (d, J = 8 Hz, 1H), 7.53-7.65 (m, 2H), 12.74 (br.s, 1H).