Reaction Steps
Piperidine (95 μL, 0.96 mmol) was added to a suspension of 3-methoxy-4-(oct-3-ynyloxy)benzaldehyde (0.25 g, 0.96 mmol) and 2-[(carboxyacetyl)amino]benzoic acid (0.20 g, 0.90 mmol) in toluene (5 mL) and treated according to Procedure 2, acidifying with 20% AcOH. The crude product was recrystallised from EtOH/water providing (E)-2-[[3-(3-methoxy-4-(oct-3-ynyloxy)phenyl)-1-oxo-2-propenyl]amino]benzoic acid (0.30 g, 79%) as a colourless crystalline solid; mp 169-170° C.; δH (400 MHz, DMSO-d6) 0.85 (t, J=7.2 Hz, 3H, CH3), 1.31-1.42 (m, 4H, CH3CH2CH2), 2.13 (t, J=7.2 Hz, 2H, CH2), 2.60 (t, J=7.2 Hz, 2H, CH2CH2O), 3.83 (s, 3H, OCH3), 4.05 (t, J=7.2 Hz, 2H, OCH2), 6.76 (d, J=15.6 Hz, 1H, CH═CHCO), 7.00 (d, J5′,6′=8.0 Hz, 1H, H5′), 7.15 (t, J3,4=J4,5=8.0 Hz, 1H, H4), 7.22 (dd, J5′,6′=8.0, J2′,6′=1.6 Hz, 1H, H6′), 7.37 (d, J5′,6′=1.6 Hz, 1H, H2′), 7.55 (d, J=15.6 Hz, 1H, CH═CHCO), 7.60 (t, J4,5=J5,6=8.0 Hz, 1H, H5), 8.00 (d, J3,4=8.0 Hz, 1H, H3), 8.62 (d, J5,6=8.0 Hz, 1H, H6), 11.30 (s, 1H, NH), 13.55 (br s, 1H, CO2H); δC (100 MHz, DMSO-d6) 13.4, 17.7, 19.2, 21.3, 30.4, 55.7, 67.0, 76.7, 81.6, 110.9, 113.0, 116.7, 120.1, 120.3, 122.5, 122.6, 127.6, 131.1, 133.9, 141.0, 141.5, 149.1, 149.5, 164.1, 169.4; HRMS (ESI) calculated for C25H27NO5 [M+H]+ 421.1962. found 421.1962; vmax 757, 1143, 1220, 1514, 1601, 1652, 1690, 2939 cm−1.
