Bioinspired Total Synthesis of (±)-Chaetophenol C Enabled by a Pd-Catalyzed Cascade Cyclization

A novel;Pd(II)-catalyzed cascade reaction has been developed that: consists of a highly regie- and stereoselective oxa [4 + 2] cycloaddition reaction of o-alkynylbenzaldchydes and an intramoledilar carboxylic group quenching of the in situ generated oxonium ion. This new reaction provides a oneistep: construction of the tetracyclic core, structure of chaetophenpl C from two;simple starting rnaterials. The developed, chemistry was successfully applied to the first total synthesis of chaetophenol C and dozens of its analogues.