Rh-catalyzed intramolecular aromatic C-H insertion of α-diazo β-ketoesters: synthesis of 4-carbonyl chroman derivatives

A Rh-catalyzed intramolecular aromatic C-H insertion of α-diazo β-ketoesters was developed. This protocol offers a practical strategy for the synthesis of 4-carbonyl chroman derivatives with high yield and is compatible with a wide variety of substituents. Synthetic applications of the 4-carbonyl chroman were also demonstrated.