Rapid Access to Fused Tetracyclic N-Heterocycles via Amino-to-Alkyl 1,5-Palladium Migration Coupled with Intramolecular C(sp<sup>3</sup>)–C(sp<sup>2</sup>) Coupling
An unprecedented route for the preparation of fused tetracyclic N-heterocycles is presented through the palladium-catalyzed cyclization of isocyanides with alkyne-tethered aryliodides. In this transformation, a novel amino-to-alkyl 1,5-palladium migration/intramolecular C(sp3)–C(sp2) coupling sequence was observed first. More importantly, isocyanide exhibited three roles, serving simultaneously as