Synthesis
To a 500 mL two-necked round-bottomed flask equipped with a magnetic stirrer and argon protection was added 7-(4-bromobutoxy)-3,4-dihydro-2(1H)-quinolinone (5b, 10 g, 0.033 mol) and THF (200 mL). To the above mixture was added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (30.4 g, 0.13 mol) at room temperature with continuous stirring until the reaction was complete (progress of the reaction was monitored by TLC). Upon completion of the reaction, THF was removed by evaporation under reduced pressure.The resulting residue was washed with water (200 mL) and extracted with ethyl acetate (3 x 100 mL). The organic layers were combined, washed with saturated saline, dried over anhydrous Na2SO4 and concentrated under reduced pressure to obtain the crude product. The crude product was purified by column chromatography using ethyl acetate and hexane as eluents to afford the target compound 7-(4-bromobutoxy)-2(1H)-quinolinone (8b). Yield: 98.99% (9.8 g).
1H NMR (400 MHz, DMSO-d6) δ 11.57 (s, 1H), 7.77 (d, J = 9.4 Hz, 1H), 7.53 (d, J = 9.4 Hz, 1H), 6.83-6.69 (m, 2H), 6.27 (d, J = 9.6 Hz, 1H), 4.02 (t, J = 6.1 Hz, 2H), 3.59 (t, J = 6.6 Hz, 2H), 2.03-1.89 (m, 2H), 1.89-1.74 (m, 2H).
13C NMR (100 MHz, DMSO-d6): δ 162.67, 160.72, 141.05, 140.44, 129.69, 118.97, 113.77, 111.19, 99.05, 67.28, 35.26, 29.46, 27.74; δ 296 [t = 6.6 Hz], 2.03-1.89 (m, 2H), 1.89-1.74 (m, 2H).
ESI-MS: 296 [M + H]+.
HPLC purity: 99.26% [retention time: 11.545 min; detection wavelength: 210 nm; column: X Bridge C-18, 150×4.6 mm, particle size 5 μm; mobile phase: A) 0.1% TFA aqueous solution, B) acetonitrile; gradient program: 0 min/10% B, 3 min/10% B, 15 min/95% B, 23 min/95% B, 25 min/95% B, 25 min/95% B, 23 min/95% B, 23 min/95% B, 23 min/95% B, 23 min/95% B, 23 min/95% B. 23 min/95% B, 25 min/10% B, 30 min/10% B; Flow rate: 1.0 mL/min; Diluent: acetonitrile:water (80:20)].
The 1H NMR spectral data of compound 8b is in agreement with the values reported in the literature.
References
[1] Journal of Chemical Sciences, 2018, vol. 130, # 6,
[2] Synthetic Communications, 2007, vol. 37, # 24, p. 4337 - 4341
