ethyl 2-oxohexanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of phenylhydrazine (1.0 g, 6.92 mmol) in absolute ethanol (50 mL) was placed in an oil bath at 60° C. and a reflux condenser attached. Ethyl 2-oxohexanoate (1.0 g, 6.33 mmol) (prepared according to Singh, J; Kissick, T. P.; Mueller, R. H. Organic Preparations and Procedures International (1989), 21(4), 501-4.) was added dropwise. The reaction mixture was heated to reflux and stirred for 18 h. Water (25 mL) and EtOAc (25 mL) were added and the layers separated. The aqueous layer was extracted with EtOAc (2×25 mL), the organic layers combined, dried over sodium sulfate, filtered and concentrated. Trituration of the crude material (9:1 hexanes/EtOAc) afforded ethyl 3-propyl-1H-indole-2-carboxylate (0.850 g, 58%) as a yellow solid. 1H NMR (400 MHz, DMSO-d6): δ ppm 11.46 (s, 1H) 7.65 (d, 1H) 7.40 (d, 1H) 7.25 (d, 1H) 7.04 (t, 1H) 4.33 (q, 2H) 3.02 (t, 2H) 1.56-1.67 (m, 2H) 1.35 (t, 3H) 0.91 (t, 3H). MS: m/z 232.0 (M+1). a reflux condenser attached The reaction mixture was heated to reflux the layers separated The aqueous layer was extracted with EtOAc (2×25 mL) dried over sodium sulfate filtered concentrated