Reaction Steps
A suspension of (1E,4E)-1,5-di(pyridin-4-yl)penta-1,4-dien-3-one (1 g, 3.2 mmol) in DMF (10 mL) was treated with N-methylamine (40% in H2O, 2.8 mL, 32 mmol) at 0° C. The solution was warmed up to ambient temperature and stirred for 6 h at RT. The reaction mixture was poured into ice-water and the resulting precipitate was filtered. The aqueous solution was extracted with DCM and the combined organic layers were dried with MgSO4, filtered and evaporated in vacuo. The crude product was purified by flash-chromatography (CH2Cl2/MeOH 9:1) to obtain NW-B591 as a bright yellow solid (417 mg, 48%) (note: mixture of cis/trans isomers in a ratio of 4:1). mp: 103-106° C. 1H NMR (300 MHz, CDCl3) δ (ppm): 8.65 (dd, 4J=4.5 Hz, 3J=1.5 Hz, 4 H, HAr), 7.42 (dd, 3J=4.5 Hz, 4J=1.6 Hz, 4 H, HAr), 3.51 (dd, 3J=12.0 Hz, J=3.2 Hz, 2 H, CH2), 2.82-2.68 (m, 2 H, CH), 2.57-2.46 (m, 2 H, CH2), 1.89 (s, 3 H, CH3). Signals of the minor isomer: 8.65-8.60 (m, 4 H, HAr), 7.25 (dd, 3J=4.7 Hz, 4J=1.5 Hz, 4 H, HAr), 4.13 (t, 3J=6.0 Hz, 2 H, CH), 2.96-2.86 (m, 2 H, CH2), 2.86 (ddd, J=7.9, J=6.0 Hz, J=1.2 Hz, 2 H, CH2), 2.19 (s, 3 H, CH3). 13C NMR (75 MHz, CDCl3) δ (ppm): 204.3 (C), 151.6 (C), 150.4 (CH), 122.2 (CH), 68.9 (CH), 49.6 (CH2), 41.1 (CH3).
