Hydrochloric Acid → 2-oxo-3-(2-oxo-2,3-dihydro-1H-benzimidazol-5-ylmethyl)-2,3-dihydrobenzoxazole-5-carboxylic acid

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Reaction Conditions

Reaction Steps

1.1 g (3.24 mmol) of methyl 2-oxo-3-(2-oxo-2,3-dihydro-1H-benzimidazol-5-ylmethyl)-2,3-dihydrobenzoxazole-5-carboxylate are suspended in 20 ml of water, 30 ml of conc. hydrochloric acid are added, and the mixture is stirred at a bath temperature of 100° C. for 24 h. A further 20 ml of conc. HCl are added, and the reaction mixture is stirred at a bath temperature of 130° C. for 3 days. The suspension is filtered and washed with water, and the residue is dried at 50° C. in a drying cabinet; product: 996 mg; m.p. 230-231° C.; ESI 326; HPLC: Rt=4.24 min (method A).

Provenance & Evidence