Synthesis of Dihydroquinolinone Derivatives via the Cascade Reaction of o-Silylaryl Triflates with Pyrazolidinones.

Presented herein is a novel synthesis of dihydroquinolinone derivatives through an unprecedented cascade reaction of o-silylaryl triflates with pyrazolidinones. Mechanistically, the formation of the title products is believed to involve a cascade procedure including in situ formation of aryne and its addition with pyrazolidinone followed by N-N bond cleavage and intramolecular C-C bond formation/annulation. Compared with literature methods for the synthesis of dihydroquinolinones, this protocol has advantages such as multistep transformations accomplished in one pot, broad substrate scope, mild reaction conditions, and good tolerance of diverse functional groups. In addition, the products thus obtained demonstrated significant in vitro antiproliferative activity in selected human cancer cell lines.