4-Fluorobenzenesulfonyl chloride → (R)-(1-(4-fluorophenyl)-6-((4-fluorophenyl)sulfonyl)-4,4a,5,6,7,8-hexahydro-1H-pyrazolo[3,4-g]isoquinolin-4a-yl)(thiazol-2-yl)methanone

Participants

Reaction Steps

A solution of (R)-tert-butyl 1-(4-fluorophenyl)-4a-(thiazole-2-carbonyl)-4a,5,7,8-tetrahydro-1H-pyrazolo[3,4-g]isoquinoline-6(4H)-carboxylate (0.25 g, 0.520 mmol) in dichloromethane (8 mL) and trifluoroacetic acid (2 mL) was stirred at room temperature for 90 minutes, then evaporated, azeotroping twice with toluene to give a brown oil. This material was re-dissolved in dichloromethane (8 mL), and diisopropylethylamine (0.454 mL, 2.60 mmol) was added, followed by 4-fluorobenzene-1-sulfonyl chloride (0.121 g, 0.624 mmol), and the reaction mixture stirred at room temperature for 48 hours. The reaction mixture was then evaporated in vacuo and the residue purified by column chromatography on silica gel (gradient: 0 to 40% ethyl acetate in isohexane) to give a white solid (204 mg). 80 mg of this sample was purified by preparative HPLC (Varian, Acidic (0.1% Formic acid), Waters X-Select Prep-C18, 5 μm, 19×50 mm column, 25-80% acetonitrile in water) to afford (R)-(1-(4-fluorophenyl)-6-(4-fluorophenyl)sulfonyl)-4,4a,5,6,7,8-hexahydro-1H-pyrazolo[3,4-g]isoquinolin-4a-yl)(thiazol-2-yl)methanone as a pale yellow solid (45 mg). LCMS (Method F, ES-API): RT 2.58 min, m+H=538.9; 1H NMR (400 MHz, CDCl3): δ 8.02 (d, 1H, J=3.1 Hz), 7.75-7.70 (m, 2H), 7.68 (d, 1H, J=3.1 Hz), 7.45-7.40 (m, 2H), 7.29 (s, 1H), 7.20-7.11 (m, 4H), 6.53 (d, 1H, J=2.2 Hz), 5.49 (dd, 1H, J=12.3, 2.0 Hz), 4.20 (d, 1H, J=16.8 Hz), 3.93-3.86 (m, 1H), 2.94-2.83 (m, 2H), 2.74 (d, 1H, J=12.4 Hz), 2.57-2.47 (m, 2H).

Provenance & Evidence