Acetic Acid → N-methyl(3-methylbenzo[b]thiophen-2-yl)methanamine

Participants

Reaction Steps

To a stirred solution of 3-methylbenzo[b]thiophene-2 carboxaldehyde (05 g, 2.8 mmole) in methanol (15 mL) was added 2.0 M methylamine in methanol (6 mL, 12 mmole) and HOAc (0.32 mL, 5.7 mmole). The reaction was stirred at RT for hr, then sodium cyanoborohydride (0.2 g, 3 mmole) was added in one portion. After stirring for an additional 16 hr the reaction was concentrated to dryness. The residue was taken up in Et2O and washed with 1.0 N NaOH then with brine, dried (Na2SO4), and concentrated under vacuum. Purification by flash chromatography on silica gel (95:5 CHCl3/methanol containing 5% NH4OH) gave the title compound (0.30 g, 56%) as a yellow oil: 1H NMR (400 MHz, CDCl3) δ 7.77 (d, J=7.8 Hz, 1 H), 7.62 (d, J=7.9 Hz, 1 H), 7.34 (t, 1 H), 7.28 (t, 1 H), 3.99 (s, 2 H), 2.49 (s, 3 H), 2.34 (s, 3 H), 1.77 (br s, 1 H).

Provenance & Evidence