Pyridine → {2-[(5-Bromo-benzofuran-2-carbonyl)-amino]-phenyl}-carbamic acid tert-butyl ester

Participants

Reaction Steps

A mixture of 5290 mg (21.95 mmol) 5-Bromo-benzofuran-2-carboxylic acid (Owen, C. P., et al., J. Pharm. Pharmacol. 51 (1999) 427–434) and 20 ml thionyl chloride was heated at reflux for 4 h. The excess thionyl chloride was evaporated, 20 ml toluene were added and evaporated again. The residue was dissolved in 50 ml dichloromethane and 2.0 ml pyridine and a solution of 4373 mg (21.0 mmol) mono-boc-orthophenylenediamine in 30 ml dichloromethane were added at 0° C. After 12 h the precipitate was filtered off and washed with diethyl ether to give a first crop of 6550 mg (15.2 mmol) {2-[(5-Bromo-benzofuran-2-carbonyl)-amino]-phenyl}-carbamic acid tert-butyl ester (56). The solvent of the mother liquid was removed and 250 ml ethyl acetate were added to the residue. The organic phase was washed with 5% aqueous citric acid, saturated aqueous sodium bicarbonate solution and brine and dried over Na2SO4. 50 ml heptane were added to the solution and the solvent was evaporated to give another 1000 mg of (2.32 mmol) of {2-[(5-Bromo-benzofuran-2-carbonyl)-amino]-phenyl}-carbamic acid tert-butyl ester (56).

Provenance & Evidence