To a 100 mL round bottomed flask with a stirring bar and an argon inlet was added 1-[1-(4-fluorobenzyl)-5-phenyl-1H-pyrrol-2-yl]ethanone AV-8-1 (0.628 g, 2.14 mmol), dry THF (10 mL), diethyl oxalate (0.41 mL, 3.00 mmol) and NaOEt (0.204 g, 3.00 mmol). The resulting mixture was stirred 1 h at ambient temperature. The mixture was diluted with EtOAc and washed with 1N HCl, H2O (2×) and brine. Drying (MgSO4) filtration and removal of the solvent in vacuo gave 4-[1-(4-fluorobenzyl)-5-phenyl-1H-pyrrol-2-yl]-2,4-dioxobutyric acid ethyl ester AV-9-1 as an oil. This material was used without further purification. 1H NMR (CDCl3) δ 1.38 (3H, t, j=7.1 Hz), 4.38 (2H, q, j=7.1 Hz), 5.65 (2H, s), 6.38 (1H, d, j=4.1 Hz), 6.79 to 6.94 (4H, m), 7.29 (2H, m), 7.39 (3H, m).
