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-N-methacryloylbenzamides and 2-(2-iodophenyl)-1H-indoles) and 1,n-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-a]isoquinolinones. The method exhibits a broad substrate scope and excellent regioselectivity.