2-Methyltetrahydrofuran → (E)-4-(2-(2-chloro-4-fluorophenyl)-1-(1-(tetrahydro-2H-pyran-2-yl)-1H-indazol-5-yl)but-1-en-1-yl)benzaldehyde

Participants

Reaction Conditions

Reaction Steps

A round-bottom flask equipped with a magnetic stir bar, a reflux condenser, internal thermometer, and a N2 inlet was charged with 5-(but-1-yn-1-yl)-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole (50.0 g, 197 mmol; Intermediate 3), bis(pinacolato)diboron (50.4 g, 199 mmol), and anhydrous 2-methyltetrahydrofuran (393 mL) followed by Pt(PPh3)4 (1.83 g, 1.5 mmol). This mixture was degassed with three vacuum/N2 cycles, heated at 83° C. (internal temperature; oil bath at 95° C.) for 5 h under N2, and then allowed to cool to room temperature. 2-Methyltetrahydrofuran (393 mL), cesium carbonate (128.1 g, 393 mmol), and water (11.8 mL, 1.5% v/v) were added, and the reaction was cooled to 4° C. 4-Iodobenzaldehyde (45.6 g, 197 mmol) and PdCl2(PPh3)2 (6.90 g, 9.8 mmol) were added, and the reaction was degassed with three vacuum/N2 cycles. The mixture was allowed to warm to room temperature and stirred overnight. Aqueous KOH solution (4M, 275 mL, 1100 mmol) and 2-chloro-4-fluoroiodobenzene (70.6 g, 275 mmol) were added. The reaction was degassed with 3 vacuum/N2 cycles, heated at 75° C. (internal temperature; oil bath at 90° C.) for 7 h under N2, and then allowed to cool to room temperature. The layers were separated, and the organic layer was washed with brine (800 mL), dried over sodium sulfate, filtered, and concentrated. The crude product was purified by silica gel chromatography (0-20% ethyl acetate in hexanes) to give the title compound (82.6 g, 7:1 mixture of regioisomers) as a pale yellow foam. Data for major isomer; (E)-4-(2-(2-chloro-4-fluorophenyl)-1-(1-(tetrahydro-2H-pyran-2-yl)-1H-indazol-5-yl)but-1-en-1-yl)benzaldehyde: 1H NMR (300 MHz, DMSO-d6): δ 9.82 (s, 1H), 8.15 (s, 1H), 7.78-7.71 (m, 2H), 7.61 (d, 2H), 7.43-7.27 (m, 3H), 7.15 (m, 3H), 5.86 (dd, 1H), 3.93-3.85 (m, 1H), 3.79-3.68 (m, 1H), 2.44-2.36 (m, 3H), 2.10-1.96 (m, 2H), 1.81-1.67 (m, 1H), 1.63-1.53 (m, 2H), 0.92 (t, 3H);

Provenance & Evidence