Citric Acid → HCID 69487009, compound

Participants

Reaction Steps

To a suspension of 732 mg (1.5 mmol) benzoic acid 2-(2-tert-butoxycarbonylamino-phenylcarbamoyl)-benzo[b]thiophen-5-yl ester (3) in 30 ml methanol was added 1.0 ml of a 5.4M solution of NaOMe in methanol. After 3 h at room temperature the reaction solution was poured on 5% aqueous citric acid. Extraction with ethyl acetate, washing of the organic phase with brine. The organic phase was dried over sodium sulfate, the solvent was evaporated and the residue subjected to silica gel chromatography (petrolether/ethyl acetate 3:1). {2-[(5-Hydroxy-benzo[b]thiophene-2-carbonyl)-amino]-phenyl}-carbamic acid tert-butyl ester (4) was recrystallized from ethyl acetate/diethyl ether to yield 546 mg (1.42 mmol) as colorless crystals, mp. 185° C. (decomp.).

Provenance & Evidence