Methylamine → (5-Chloro-3-methyl-benzo[b]thiophen-2-ylmethyl)methylamine

To 5-chloro-3-methyl-benzo[b]thiophene-2-carbaldehyde (5.10 g, 24.2 mmol) was added a solution of 2 M methylamine in methanol (81 mL) and the resulting mixture was stirred overnight at room temperature. The mixture was concentrated under reduced pressure and the residue taken up in ethanol (81 mL). The solution was cooled to 0° C., NaBH4 (1.37 g, 36.3 mmol) was added in one portion, and stirring was continued overnight. The mixture was concentrated under reduced pressure and the residue was combined with 1 M NaOH (200 mL). The mixture was extracted with diethyl ether (3×150 mL). The combined organics were washed with brine (100 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to the title compound (4.83 g, 88%) as a pale yellow oil which crystallized under vacuum: 1H NMR (300 MHz, CDCl3) δ 7.69-7.59 (m, 2H), 7.25 (m, 1H), 3.96 (s, 2H), 2.50 (s, 3H), 2.31 (s, 3H).