Divergent Synthesis of Fused Tetracyclic Heterocycles from Diarylalkynes Enabled by the Selective Insertion of Isocyanide.

Herein, we present a direct and efficient synthesis of diverse polysubstituted fused tetracyclic heterocycles with good functional group tolerance from diarylalkynes under different palladium catalytic systems. In this chemistry, an unprecedented intermolecular nucleopalladation of diarylalkynes through the highly selective sequential double insertion of isocyanide was achieved for the first time. The practicality of this method was further demonstrated by the construction of various bioactive molecules and important structural motifs, with potential applications in materials science and biochemistry. In addition, density functional theory calculations (DFT) elucidated an interesting "Pd walk" during the cyclization process.