2-Thiophenecarboxaldehyde → N-[(Thiophen-2-yl)methyl]ethanamine

Participants

Reaction Conditions

Reaction Steps

To a 0° C. chilled round bottom flask was added ethyl amine hydrochloride (4.58 g, 56.17 mmol) and thiophene-2-carbaldehyde (5.0 mL, 53.50 mmol) in methanol (20.0 mL), followed by triethylamine (7.83 mL, 56.17 mmol) and the reaction was stirred for 30 minutes. Sodiumtriacetoxyborohydride (15.87 g, 74.90 mmol) was added in one portion under vigorous stirring. The ice bath was removed and the flask was attached to a bubbler to allow gas evolution and expansion. The reaction was stirred overnight at room temp. Most of the volatiles were evaporated in vacuo. The reaction mixture was quenched by adding 1 N NaOH, and the product was extracted with dichloromethane. The organic extract was washed with brine and dried over MgSO4. The volatiles were evaporated to give the crude free base N-(thiophen-2-ylmethyl)ethanamine (5.85 g, 41.42 mmol, 77%), which resulted of a purity grade >97% by 1H-NMR analysis, therefore it was used in the next step without any further purification. 1H NMR (400 MHz, CDCl3) δ 1.13 (t, J=7.1 Hz, 3H), 2.71 (q, J=7.2 Hz, 2H), 4.00 (d, J=0.7 Hz, 2H), 6.90-6.97 (m, 2H), 7.21 (dd, J=5.0, 1.3 Hz, 1H).

Provenance & Evidence