Trifluoroacetic acid → 1-(5-Chlorospiro[indoline-3,4'-piperidin]-1-yl)ethanone

Participants

Reaction Steps

Trifluoroacetic acid (25 ml) was added to a stirred solution of 1-acetyl-5-chlorospiro[indoline-3,4′-piperidine]-1′-carboxylic acid tert-butyl ester (8 g) in anhydrous dichloromethane (250 ml) under an atmosphere of nitrogen. The reaction was left as such for 3 h. The reaction was washed with saturated bicarbonate solution (200 ml) and dried over sodium sulphate and concentrated in vacuo to yield an off white solid. Flash chromatography [SiO2: methanol-dichloromethane-triethylamine (90:5:5)] yielded 5.6 g (61%) of the desired 1-Acetyl-5-chlorospiro[indoline-3,4′-piperidine]. 1H NMR (400 MHz, CDCl3) δ 6:1 mixture of rotamers. Major rotamer 1.70 (m, 2H), 1.80 (m, 2H), 2.27 (s, 3H), 2.75 (t, J=12 Hz, 2H), 3.15 (m, 2H), 3.90 (s, 2H), 7.12 (d, J=1 Hz, 1H), 7.18 (dd, J=7 & 1 Hz, 1H), 8.15 (d, J=7 Hz, 1H). Minor rotamer (partial data) 2.44 (s, 3H), 2.86 (m, 2H), 3.10 (m, 2H), 4.05 (s, 2H). MS (ES+) 265/267 (M+H+).

Provenance & Evidence