Hydrochloric Acid → 4-(2,3-Dihydro-2-oxo-1H-benzimidazol-1-yl)-1-piperidineacetic acid

Participants

Reaction Steps

A solution of ethyl (4-(2-keto-1-benzimidazolinyl)piperidin-1-yl)acetate (13.0 g, 42.8 mmol) in methanol (150 mL) was treated with an aqueous solution of sodium hydroxide (3 N, 30 mL, 90 mmol) and heated at reflux for 2 hours. The solution was cooled to room temperature and neutralized with the addition of concentrated hydrochloric acid (12 N, 7.5 mL). The solvent was evaporated in vacuo, and the resultant amorphous solid was dried in vacuo with heating (˜50° C.) overnight to give (4-(2-keto-1-benzimidazolinyl)piperidin-1-yl)acetic acid (17.2 g) which was used in the subsequent step without purification. MS m/z 304 (MH+); NMR(DMSO-d6): δ 1.74 (br d, 2 H), 2.53-2.67 (m, 2 H), 2.74-2.86 (m, 2 H), 3.33 (s, 2 H), 4.29-4.42 (m, 1 H), 6.97-7.05 (m, 3 H) and 7.38-7.43 (m, 1 H).

Provenance & Evidence