Rh(III)-Catalyzed Cascade Annulation of 5-Amino-1-aryl-pyrazoles with Pyridotriazoles for the Synthesis of Benzo[ <i>f</i> ]pyrazolo[1,5- <i>a</i> ][1,3]diazepin-5-ones

Herein, we developed a protocol for the synthesis of highly functionalized benzo[<i>f</i>]pyrazolo[1,5-<i>a</i>][1,3]diazepin-5-one derivatives <b>3</b> (BPDOs) from 5-amino-1-aryl-pyrazole derivatives with pyridotriazoles. This strategy involved a directing group-functionalization group (DG-FG) relay, entailing the heating of a mixture of substrates <b>1</b> and <b>2</b> in toluene, catalyzed by [Cp*RhCl₂]₂ with AgNTf₂ as a promoter and adamantanoic acid as an additive. As a result, a series of BPDOs <b>3</b> were produced via the cleavage of two bonds (one C-N and one N-N) and the formation of two new bonds (one C-C and one C-N) in a single step. Importantly, the introduction of pyridyl groups through this method enhances the overall functionality and diversity of the resulting compounds, which is critical for their potential applications in medicinal chemistry. This protocol realizes the DG-FG relay reaction, utilizing the N(2) atom as the directing group and the 5-position amino group in the cyclization. The [5 + 2] cyclization efficiently constructed the tricyclic benzo[<i>f</i>]pyrazolo-[1,5-<i>a</i>][1,3]diazepin-5-one core, which is challenging to synthesize using conventional methods. These strategies enable the one-pot synthesis of functionalized BPDOs, making them suitable for combinatorial and parallel syntheses, laying a foundation for future studies of their chemical properties and biological activities.