Controllable construction of isoquinolinedione and isocoumarin scaffolds via RhIII-catalyzed C–H annulation of N-tosylbenzamides with diazo compounds

A highly efficient protocol for the synthesis of isoquinolinediones by RhIII-catalyzed C–H activation/annulation/decarboxylation of N-tosylbenzamides with diazo compounds is reported. The switchable synthesis of isocoumarins was also achieved successfully via C–H activation/annulation with slight modification of the reaction conditions. Importantly, the synthetic utility of this new reaction was further demonstrated in an atom-economical and operationally convenient total synthesis of a TDP2 inhibitor derivative from commercially available starting materials.