Synthesis of Substituted 2,3-Benzodiazepines

A new, four-step synthetic route for substituted 2,3-benzodiazepines <b>1</b>, starting from aldehyde <b>4</b>, was developed with excellent overall yields. This route included the 1,2-addition of various aromatic Grignard reagents to <b>4</b>, PCC oxidation, and aerobic Wacker-type oxidation of the olefinic group of <b>6</b>, followed by condensation of the resulting 1,5-dicarbonyl <b>7</b> with N<sub>2</sub>H<sub>4</sub>. Isoquinolones <b>9</b> were obtained when an aldehyde group was used instead of a ketone. The key structures were confirmed by X-ray single-crystal diffraction analysis.