Synthesis of 1,3-Benzodiazepines through [5 + 2] Annulation of <i>N</i>-Aryl Amidines with Propargylic Esters

Abstract

In this paper, an efficient synthesis of functionalized 1,3-benzodiazepines through an unprecedented [5 + 2] annulation of <i>N</i>-aryl amidines with propargylic esters is presented. The reactions proceed through Rh(III)-catalyzed C(sp²)-H alkenylation followed by annulation and deacetoxylation along with cascade C-H/N-H/C-O bond cleavage and C-C/C-N bond formation. Furthermore, the cytotoxicity of selected products against several human cancer cell lines was tested, which demonstrated their good potential for pharmaceutical applications.