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Ethyl pyruvate (3.7 ml, 33.3 mmol) was added to a solution of 2,3-dihydro-indol-1-ylamine (4.216 g, 31.4 mmol) in absolute ethanol (40 ml). The mixture was heated to reflux for 1 hour before being evaporated to dryness. The residue was dissolved in acetic acid (40 ml) and boron trifluoride etherate (4.0 ml 31.4 mmol) added. The mixture was heated to reflux for 1 hour then poured into ethyl acetate (200 ml). The ethyl acetate was washed with water (1 L), saturated sodium hydrogen carbonate (2×300 ml) and brine (100 ml). After drying over anhydrous magnesium sulfate the mixture was evaporated to dryness and the residue purified by flash column chromatography (SiO2, 7% to 10% EtOAc in hexanes) to afford 4,5-dihydro-pyrrolo[3,2,1-hi]indole-2-carboxylic acid ethyl ester as a yellow solid (1.117 g). 400 MHz 1H NMR (DMSO-d6) δ: 7.35 (d, J=6.8 Hz, 1H), 7.12 (s, 1H), 7.04-6.99 (m, 2H), 4.73 (t, J=6.8 Hz, 2H), 4.37 (q, J=7.2 Hz, 2H), 3.77 (t, J=6.8 Hz, 2H), 1.41 (t, 6.8 Hz, 3H); LCMS: 216 [M+H].

1. temperatureThe mixture was heated
2. temperatureto reflux for 1 hour
3. custombefore being evaporated to dryness
4. dissolutionThe residue was dissolved in acetic acid (40 ml)
5. temperatureThe mixture was heated
6. temperatureto reflux for 1 hour
7. washThe ethyl acetate was washed with water (1 L), saturated sodium hydrogen carbonate (2×300 ml) and brine (100 ml)
8. dry with materialAfter drying over anhydrous magnesium sulfate the mixture
9. customwas evaporated to dryness
10. customthe residue purified by flash column chromatography (SiO2, 7% to 10% EtOAc in hexanes)