A new and efficient palladium-catalyzed synthesis of a 2,3,4,5-tetrahydro-1H-2,4-benzodiazepine-1,3-dione derivative

The palladium-catalyzed intramolecular cyclization of 1-butyl-1(o-iodobenzyl)-3-phenylurea 1 at 80 degrees C in the presence of carbon monoxide at atmospheric pressure gives the corresponding 2,3,4,5-tetrahydro-1H-2,4-benzodiazepine-1,3-dione derivative 2 in 91% yield. Yield and selectivity are strongly affected by the solvent. (