Reaction Steps
Piperidine (190 μL, 1.9 mmol) was added to a suspension of 4-methoxy-3-(oct-3-ynyloxy)benzaldehyde (0.50 g, 1.9 mmol) and 2-[(carboxyacetyl)amino]benzoic acid (0.39 g, 1.7 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-(4-methoxy-3-(oct-3-ynyloxy)phenyl)-1-oxo-2-propenyl]amino]benzoic acid (0.60 g, 82%) as a colourless crystalline solid; mp 157-158° C.; δH (400 MHz, DMSO-d6) 0.85 (t, J=7.2 Hz, 3H, CH3), 1.32-1.42 (m, 4H, CH3CH2CH2), 2.14 (t, J=7.2 Hz, 2H, CH2), 2.62 (t, J=7.2 Hz, 2H, CH2CH2O), 3.80 (s, 3H, OCH3), 4.10 (t, J=7.2 Hz, 2H, OCH2), 6.80 (d, J=15.6 Hz, 1H, CH═CHCO), 7.00 (d, J5′,6′=8.0 Hz, 1H, H5′), 7.16 (t, J3,4=J4,5=8.0 Hz, 1H, H4), 7.25 (d, J5,6′=8.0 Hz, 1H, H6′), 7.40 (s, 1H, H2′), 7.55 (d, J=15.6 Hz, 1H, CH═CHCO), 7.61 (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), 11.27 (s, 1H, NH), 13.58 (br s, 1H, CO2H); δC (100 MHz, DMSO-d6) 13.4, 17.8, 19.3, 21.3, 30.5, 55.6, 67.1, 76.9, 81.5, 111.9, 112.1, 116.6, 120.0, 120.3, 122.6, 122.9, 127.3, 131.1, 134.0, 141.0, 141.5, 147.9, 150.8, 164.2, 169.4; HRMS (ESI) calculated for C25H27NO5 [M+H]+ 421.1962. found 421.1962; vmax 757, 1131, 1259, 1515, 1582, 1671, 2954, 3335 cm−1.
