N-bromobutanimide → 5-Bromo-1'-methylspiro[indole-3,4'-piperidin]-2(1H)-one

Participants

Reaction Steps

A solution of 1′-(methyl)spiro[indole-3,4′-piperidin]-2(1H)-one (6.3 g, 29.1 mmol) in CH3CN (100 ml) and MeOH (5 ml) was cooled to −5° C. and NBS (7.8 g, 44 mmol) was slowly added with stirring. The reaction mixture was stirred for 3.5 h at 0° C. Solvent was removed by vacuo. The residue was purified by silica gel chromatography (2-20% MeOH/CH2Cl2) to give 6 g as a solid. The solid compound was dissolved in ethyl acetate (600 ml) and washed with saturated aqueous NaHCO3 solution, dried (Na2SO4). Evaporation of the solvent in vacuo gave 4.2 g (47%) of 11. 1HNMR (CD3OD, 400 MHz) δ 7.51 (d, J=1.8 Hz, 1H), 7.35 (dd, J=1.9 and 8.2 Hz, 1H), 6.81 (d, J=8.2 Hz, 1H), 2.93 (m, 2H), 2.67 (m, 2H), 2.41 (s, 3H), 1.86 (m, 4H).

Provenance & Evidence