Dimethyl Sulfate → N-Methyloxindole

Participants

Reaction Steps

A stirred mixture of sodium hydride (60%, 31 g, 0.79 mol) in dry xylene (500 mL), under a nitrogen atmosphere, was heated to reflux for 30 min. 1,3-Dihydro-indol-2-one 16a (100 g, 0.75 mol) was then slowly added via an addition funnel and stirred at reflux for 1.5 hours. Dimethyl sulfate (104 g, 0.83 mol) was added drop-wise, whereupon the resulting homogeneous solution was refluxed for an additional 2 hours. After cooling to room temperature, the reaction mixture was washed with water, dried over Na2SO4, and concentrated under reduced pressure to afford 1-methyl-1,3-dihydro-indol-2-one 16b (74 g, 67.3%). 1H NMR (300 MHz, CDCl3) δ 7.23-7.31 (m, 2H), 7.04 (t, J=7.5 Hz, 1H), 6.82 (d, J=7.8 Hz, 1H), 3.52 (s, 2H), 3.21 (s, 3H).

Provenance & Evidence