A Concise Synthesis to Benzo[c]cinnolines via 2,2'-Dinitro-1,1'-Biphenyls Attained from a Novel Tailored Suzuki Cross-Coupling

A new two-step synthetic process for the preparation of unsymmetrically substituted benzo[c]cinnolines was developed. The key intermediate 2,2'-dinitro-1,1'-biphenyl was prepared by means of an unprecedented tailored Suzuki cross-coupling protocol. The subsequent step is constituted by a domino partial nitro group reduction and intramolecular diazo bond formation, a process that afford target benzo[c]cinnoline scaffold. The disclosed method tolerates both electron-withdrawing- and electron-donating groups.