Boron trifluoride etherate → HCID 13477702, compound

Participants

Reaction Steps

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].

Provenance & Evidence