Rapid Access to Polysubstituted Tetrahydrocarbazol-4-ones via Sequential Selective C-H Functionalization from N-Nitrosoanilines

Herein, we have developed a strategy of Rh(III)-catalyzed C-H activation of N-nitrosoanilines and iodonium ylides to construct novel tetralydrocarbzol-4-one scaffolds, which provided valuable templates for sequential C-H functionalization such as alkylation, alkenylation, amidation and (hetero)arylation at C-5-position of tetralydrocarbzol-4-one with different coupling partners. Gram-scale synthesis and further transformations of tetralydrocarbzol-4-one derivatives to Ondansetron and its analogues demonstrated the utility of this protocol, which enabled the concise and diverse construction of biologically active molecules.