Piperidine → 4-(2-Hydroxy-ethyl)-3-(4-methoxy-3-thiophen-2-yl-benzylidene)-1,3-dihydro-indol-2-one

A mixture of 4-(2-hydroxy-ethyl)-1,3-dihydro-indol-2-one (1.6 g, 9.2 mmol), 4-methoxy-3-thiophen-2-yl-benzaldehyde (2 g, 9.2 mmol) and piperidine (4.5 mL, 85 mmol) in ethanol (46 mL) was heated to reflux for overnight. The reaction mixture was concentrated and the residue was chromatographed on a column of silica gel to give 1.63 g (47%) of 4-(2-hydroxy-ethyl)-3-(4-methoxy-3-thiophen-2-yl-benzylidene)-1,3-dihydro-indol-2-one as a yellow orange solid. 1HNMR (300 MHz, DMSO-d6) δ 10.53 (s, br, 1H, NH), 8.73 (d, J=2.1 Hz, 1H), 8.10 (dd, J=2.2 & 9.1 Hz, 1H), 7.74 (s, 1H, H-vinyl), 7.56-7.65 (m, 2H), 7.07-7.22 (m, 3H), 6.81 (d, J=7.5 Hz, 1H), 6.68 (dd, J=0.6, 7.5 Hz, 1H), 4.87 (t, J=4.5 Hz, 1H, OH), 3.97 (s, 3H, OCH3), 3.68-3.75 (m, 2H, CH2CH2OH), 3.09 (t, J=4.5 Hz, 2H, CH2CH2OH).