Synthesis of Fused Polycyclic 1,4-Benzodiazepines via a Metal-Free Cascade Cyclization of 2-Acylbenzoic Acids with N-(o-Aminobenzyl)-indoles

An unprecedented metal-free cascade cyclization of 2-acylbenzoic acids with N-(2-aminobenzyl)-indoles was developed, which provided a powerful method for the construction of fused polycyclic skeleton. A variety of isoindoline/indole-fused 1,4-benzodiazepines were facilely obtained in moderate to good yields in one step. This protocol features good functional group tolerance, metal-free conditions, easy scalability and versatile transformations of products.