7-Bromo-8-chloro-5-oxo-2,3,4,5-tetrahydro-benzo[b]azepine-1,4-dicarboxylic acid 1-isopropyl ester 4-methyl ester → 7-Bromo-8-chloro-5-oxo-2,3,4,5-tetrahydro-benzo[b]azepine-1-carboxylic acid isopropyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of 7-Bromo-8-chloro-5-oxo-2,3,4,5-tetrahydro-benzo[b]azepine-1,4-dicarboxylic acid 1-isopropyl ester 4-methyl ester (1.43 g, 3.42 mmol) in HOAc (30.0 ml), concentrated HCl (9.00 ml) and water (3.00 ml) was heated at 100° C. for 4 hours and then cooled down to room temperature overnight. The solvents were evaporated under reduced pressure, and the residue was partitioned between ethyl acetate (100 ml) and saturated NaHCO3 (aq) (100 ml). The aqueous layer was extracted with more ethyl acetate (20.0 ml). The combined organics washed with brine (3×120 ml), dried over Na2SO4, filtered and concentrated. The material obtained was subjected to the conditions described in step 2 to provide 7-Bromo-8-chloro-5-oxo-2,3,4,5-tetrahydro-benzo[b]azepine-1-carboxylic acid isopropyl ester (0.990 g, 80%) as white solid. MS (ES+): 360, 362 (M+H).

Provenance & Evidence