Compound 5

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

A mixture of (R)-3-bromo-6-((4-hydroxy-1-(4,4,4-trifluoro-3-phenylbutanoyl)piperidin-4-yl)methyl)-2-methyl-2H-pyrazolo[4,3-d]pyrimidin-7(6H)-one 18 (250 mg, 0.461 mmol), (4-(((tert-butoxycarbonyl)amino)methyl)phenyl)boronic acid (231 mg, 0.922 mmol), Pd(PPh₃)₄ (53 mg, 0.046 mmol), K₃PO₄ (391 mg, 1.84 mmol), 1,4-dioxane (3 mL) and water (1 mL) in a reaction tube was degassed by bubbling N₂ for 20 min. The reaction tube was sealed and the reaction was heated at 130 °C under microwave irradiation for 30 min. The reaction mixture was diluted with saturated NH₄Cl_(aq) (40 mL) and extracted with DCM (3 x 30 mL) using a Biotage phase separator. The combined organic phases were concentrated in vacuo and the residue was purified by flash chromatography (40 g GraceResolv silica, 0-100% EtOAc in cyclohexane then 0-10% MeOH in EtOAc) to give (R)-tert-butyl 4-(6-((4-hydroxy-1-(4,4,4-trifluoro-3-phenylbutanoyl)piperidin-4-yl)methyl)-2-methyl-7-oxo-6,7-dihydro-2H-pyrazolo[4,3-d]pyrimidin-3-yl)benzylcarbamate (200 mg, 65%) as a pale yellow solid. LCMS: R_T = 1.47 min, m/z 669 [M+H]⁺. A solution of (R)-tert-butyl 4-(6-((4-hydroxy-1-(4,4,4-trifluoro-3-phenylbutanoyl)piperidin-4-yl)methyl)-2-methyl-7-oxo-6,7-dihydro-2H-pyrazolo[4,3-d]pyrimidin-3-yl)benzylcarbamate (200 mg, 0.300 mmol) in DCM (2 mL) and TFA (1 mL) was stirred at RT for 15 min. The reaction mixture was purified using a 10 g SCX-2 cartridge (MeOH then 7 M in NH₃ in MeOH). The basic phases were combined, concentrated in vacuo and the residue was purified by flash chromatography (GraceResolv silica 24 g cartridge, 0-100%, EtOAc in cyclohexane then 0-25% MeOH in EtOAc; then Biotage KP-NH 11 g cartridge, 0-100%, EtOAc in cyclohexane then 0-10% MeOH in EtOAc) to give the title compound (90 mg, 52%) as a colourless solid after lyophilization. LCMS: R_T = 0.81 min (purity >99% at 254 nm), m/z 569 [M+H]⁺. ¹H NMR (500 MHz, DMSO-d₆): δ 8.02 – 7.93 (m, 1H), 7.70 – 7.60 (m, 2H), 7.57 – 7.44 (m, 2H), 7.43 – 7.38 (m, 2H), 7.38 – 7.28 (m, 3H), 4.88 (s, 1H), 4.26 – 4.02 (m, 1H), 4.10 (s, 3H), 4.02 – 3.85 (m, 3H), 3.81 (s, 2H), 3.80 – 3.71 (m, 1H), 3.26 – 3.11 (m, 2H), 3.02 – 2.80 (m, 2H), 2.43 (s, 2H), 1.61 (td, J = 12.7, 12.1, 4.3 Hz, 0.5H), 1.44 – 1.32 (m, 2.5H), 1.27 – 1.17 (m, 1H). ¹³C NMR (126 MHz, DMSO-d₆): δ 166.60 + 166.50 (conformers), 156.24 + 156.18 (conformers), 147.27 + 147.25 (conformers), 145.22, 136.02, 134.85 – 134.24 (m, due to conformers and coupling with CF₃), 129.19, 129.16, 128.37, 128.34, 128.28, 128.22, 128.02, 127.99, 127.34, 127.23, 126.07, 126.04, 125.26, 69.30 + 69.21 (conformers), 52.98 + 52.89 (conformers), 45.46 – 44.90 (m, due to conformers and coupling with CF₃), 45.35, 40.83, 39.39, 37.36 + 37.28 (conformers), 34.89 + 34.80 (conformers), 34.09 + 34.04 (conformers), 31.44. The signals between 130 – 125 ppm are complex due to the conformers and the CF₃ signals. HRMS (TOF MS ES+): m/z [M + H]⁺ Calcd for C₂₉H₃₂N₆O₃F₃ 569.2488, found 569.2509.

PubChemID:

348266824

MDL Molfile:

41589_2018_BFnchembio2528_MOESM12_ESM.mol

ChemDraw:

41589_2018_BFnchembio2528_MOESM13_ESM.cdx