Efficient synthesis of coumarin-based tetra and pentacyclic rings using phospha-palladacycles

Abstract

Palladacycle 4 has proved to be an efficient catalyst for the intramolecular C–H bond functionalization of coumaryl and pyronyl ethers leading to the synthesis of tri, tetra and pentacyclic compounds, some of which were characterized by X-ray analysis. A microwave-assisted one-pot procedure for obtaining the tetracyclic rings from 4-chlorocoumarin has also been carried out. Mechanistic studies were carried out using GC, UV-Vis and ESI MS.