Synthesis of Highly Substituted Benzofuran-containing Natural Products via Rh-catalyzed Carbonylative Benzannulation

We recently developed a novel Rh-catalyzed carbonylative benzannulation for the synthesis of indoles, benzofurans, and many related heterocycles. In this update, we demonstrated the utility of this method for the synthesis of several highly substituted benzofuran-containing natural products. The scope and limitation of the Rh-catalyzed carbonylative benzannulation was investigated in the context of natural product synthesis for the first time. This study also revealed the site-selectivity for Pd-catalyzed cross-coupling of substituted benzofurans. Two one-pot sequential cross-couplings were realized based on the observed site-selectivity. The strategy of preparing bicyclic heterocycles such as benzofurans by de novo synthesis of the benzene ring will find applications in many other related bioactive heterocycles.