Reaction Steps
Anthranilic acid (300 g, 2.08 mol) was added to a solution of Meldrum's acid (272 g, 1.98 mol) in toluene (2.0 L). The reaction flask was fitted with a Dean-Stark apparatus and the suspension was heated to reflux for 3 h. The suspension was cooled, filtered, washed with toluene and dried. 2-[(Carboxyacetyl)amino]benzoic acid (381 g, 86%) was obtained as a colourless solid; mp 171-173° C.; δH (500 MHz, DMSO-d6) 3.45 (br s, 2H, CH2), 7.16 (t, J3,4=J4,5=8.0 Hz, 1H, H4), 7.59 (td, J4,5=J5,6=8.0, J3,5=1.5 Hz, 1H, H5), 7.97 (dd, J3,4=8.0, J3,5=1.5 Hz, 1H, H3), 8.44 (d, J5,6=8.0 Hz, 1H, H6), 11.27 (s, 1H, NH), 12.83 (br s, 1H, CO2H), 13.57 (br s, 1H, CO2H); δC (125 MHz, DMSO-d6) 45.0, 117.0, 120.3, 123.1, 131.2, 134.1, 140.4, 164.9, 169.1, 169.3; νmax 760, 1234, 1385, 1544, 1684, 1712, 2653, 2964, 3119 cm−1.
