Acetic Acid → 7,7-Difluoro-3,4,6,7,8,9-hexahydropyrazino[1,2-a]indol-1(2H)-one

Participants

Reaction Steps

Into a 250-mL round-bottom flask was placed a solution of 113n (10 g, 36.73 mmol, 1.00 equiv) in toluene (100 mL) and acetic acid (1.1 g, 18.32 mmol, 0.50 equiv). See FIG. 14. The resulting solution was heated to reflux for 2 h, cooled and concentrated under vacuum. The residue was triturated in 100 mL of dry ether. The crude product was purified by recrystallization from ethanol to afford 4.43 g (53%) of 113o as a white solid. MS-ESI: [M+H]+ 227. 1H NMR (300 MHz, DMSO) δ 2.10-2.24 (2H, m), 2.59-2.64 (2H, m), 3.17-3.27 (2H, m), 3.43-3.48 (2H, m), 3.88-3.92 (2H, m), 6.44 (1H, s), 7.56 (1H, s).

Provenance & Evidence