Microwave-Assisted Synthesis of Dibenzoazepinones

Significance

Reported is a multicomponent ­reaction towards the dibenzo[c,e]azepinone scaffold, starting first via a Suzuki coupling of commercially available 2-formylphenylboronic acids and substituted ortho-bromobenzoates. After ­hydrolysis of the ester, the biaryl carboxylic acids were reacted in a microwave-assisted Ugi reaction. This reaction was optimized for the solvent and temperature, with trifluoroethanol being optimal at 110 ˚C with anhydrous sodium sulfate as additive. The range of substituents studied on the biaryl moiety was not impressive, but the range of dibenzoazepinones synthesized was. The overall yields range from mediocre to good and in one case, the cyclic azepinone was converted into the corresponding thioamide using Lawesson’s reagent.