Acetic Anhydride → 2-Acetylamino-4,5,6,7-tetrahydrobenzothiophene-3-carboxylic acid ethyl ester

Participants

Reaction Steps

Ethyl 2-amino-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate (100 g, 444 mmol) and acetic anhydride (227 g, 2.2 mol) were heated at reflux for ˜15 minutes and then allowed to cool to room temperature overnight. The reaction mixture containing white solid was filtered. The solid was rinsed with water (2 L) and dried in a vacuum oven for several hours at ˜45° C. to yield a white crystalline solid (96 g, 81%). 1H NMR (DMSO-d6) δ 4.26 (q, 2H), 2.69 (t, 2H), 2.57 (t, 2H), 2.20 (s, 3H), 1.70 (m, 4H), 1.30 (t, 3H), LCMS RT=3.48 min, [M+H]+=268.0.

Provenance & Evidence