Intermolecular Double C–H Annulation via 1,4-Pd Migration: A Modular Strategy for Heteropolycycle Construction

Herein, we report a 1,4-Pd migration-enabled intermolecular double C-H annulation between alkene-tethered aryl halides (e.g., 2-iodo-<i>N</i>-methacryloylbenzamides and 2-(2-iodophenyl)-1<i>H</i>-indoles) and 1,<i>n</i>-diynes. This transformation proceeds through a cascade sequence involving Heck cyclization, alkyl-to-aryl 1,4-Pd migration, double alkyne insertion, and C-H activation, enabling the remote construction of structurally diverse heteropolycycles, including tetracyclic fused isoquinolinediones and hexacyclic indolo[2,1-<i>a</i>]isoquinolinones. The method exhibits a broad substrate scope and excellent regioselectivity.