Reaction Steps
Piperidine (0.34 mL, 3.4 mmol) was added to a suspension of 4-(but-2-ynyloxy)-3-methoxybenzaldehyde (0.70 g, 3.4 mmol) and 2-[(carboxyacetyl)amino]benzoic acid (0.70 g, 3.4 mmol) in toluene (10 mL) and treated according to Procedure 2, acidifying with 20% AcOH. (E)-2-{[3-(4-(But-2-ynyloxy)-3-methoxyphenyl)-1-oxo-2-propenyl]amino}benzoic acid (0.70 g, 61%) was obtained as a yellow crystalline solid; mp 194-195° C.; δH (400 MHz, DMSO-d6) 1.82 (s, 3H, CH3), 3.83 (s, 3H, OCH3), 4.77 (s, 2H, OCH2), 6.79 (d, J=15.6 Hz, 1H, CH═CHCO), 7.02 (d, J5′,6′=8.4 Hz, 1H, H5′), 7.14 (t, J3,4=J4,5=8.0 Hz, 1H, H4), 7.23 (d, J5′,6′=8.4 Hz, 1H, H6′), 7.38 (s, 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), 8.61 (d, J5,6=8.0 Hz, 1H, H6), 11.33 (s, 1H, NH), 13.59 (br s, 1H, CO2H); δC (100 MHz, DMSO-d6) 3.2, 55.7, 56.4, 74.6, 83.9, 110.7, 113.3, 116.8, 120.3, 120.4, 122.3, 122.8, 127.9, 131.2, 134.0, 141.1, 141.6, 148.6, 149.3, 164.2, 169.5; HRMS (ESI) calculated for C21H19NO6 [M+Na]+ 388.1155. found 388.1158; vmax 753, 1253, 1506, 1584, 1659, 2917, 3239, 3516 cm−1.
