Mild and fast access to indenopyrans via tandem Michael addition/cyclization of enynones and 1,3-indandiones.

A novel and efficient strategy for constructing fused heterocyclic indenopyrans is established through a tandem Michael addition/cyclization reaction between enynones and 1,3-indandiones. A slight alteration in the reaction duration facilitated the formation of another indenopyran isomer. The methodology is mild, rapid, operationally simple, and atom-economical, providing good to excellent yields. Furthermore, DFT calculations were performed to evaluate the stability of the isomers, which in turn confirmed the kinetically/thermodynamically controlled product. UV-visible studies revealed that these molecules absorb light in the visible region, demonstrating their potential utility as organic photocatalysts. A brief computational study of the packing and intermolecular interactions based on single-crystal XRD was also performed.