--A solution of 7-diethylaminocoumarin-3-carboxylic acid 2 (1.15 g, 5 mmol) and tri-n-butylamine (1.38 g, 7.5 mmol) in dry DMF (50 ml) was cooled in an ice bath and treated with isobutyl chloroformate (0.715 g, 5.2 mmol). The solution was stirred in the ice bath for 0.5 h, then a solution of the amine 3 (0.8 g, 5 mmol) in dry DMF (5 ml) was added. The mixture was allowed to warm to room temp. and kept for 3 h, then diluted with EtOAc and washed thoroughly with water, dilute aq. HCl, aq. NaHCO3 and water, dried and evaporated. The residue gave a yellow solid after trituration with a little ether. A portion (400 mg) was purified by flash chromatography to give the amide 4 as yellow prisms (0.345 g), m.p. 157-158° C. after crystallisation from EtOAc-light petroleum The remaining material crystallised without chromatography to give a further portion of the product (0.55 g, total yield 45%) (Found. C, 62.6;. H, 7.3; N, 10.4. C21H29N3O5 requires C, 62.5; H, 7.2; N, 10.4%); δH 8.95 (1 H, t, J 5.5, NH), 8.68 (1 H, s, 4-H), 7.42 (1 H, d, Jortho 8.8, 5-H) , 6.64 (1 H, dd, Jmeta 2.3, 6-H), 6.49 (1 H, d, 8-H), 5.08 (1 H, br S, NH), 3.23-3.64 (8 H, m, 4×CH2), 1.44 (9 H, S, CMe3) and 1.24 (6 H, t, J7, 2×Me).
