Sodium ethoxide → 3,4,6,7,8,9-Hexahydropyrazino[1,2-a]indol-1(2H)-one

Participants

Reaction Conditions

Reaction Steps

A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and nitrogen inlet was purged with nitrogen and charged with ethyl 1-(2-aminoethyl)-4,5,6,7-tetrahydro-1H-indole-2-carboxylate 115j (1.80 g, 7.63 mmol), sodium ethoxide (1.55 g, 22.8 mmol) and ethanol (50 mL). The mixture was stirred at 55° C. for 5 h. After that time, the reaction mixture was concentrated under reduced pressure and the residue was partitioned between ethyl acetate (200 mL) and water (100 mL). The organic layer was separated, and the aqueous layer was extracted with ethyl acetate (2×100 mL). The combined organic layers were washed with brine, dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography to afford a 42% yield (605 mg) of 115k as a white solid: mp 207-209° C.; 1H NMR (500 MHz, DMSO-d6) δ 7.41 (s, 1H), 6.36 (s, 1H), 3.84 (t, 2H, J=6.0 Hz), 3.42 (m, 2H), 2.51 (t, 2H, J=6.0 Hz), 2.42 (t, 2H, J=6.0 Hz), 1.76 (m, 2H), 1.65 (m, 2H); (APCI+) m/z 191.3 (M+H)

Provenance & Evidence