Novel Synthesis of Nine-Membered Oxa-Heterocycles by Pd(0)-Catalyzed Intramolecular Heck Reaction via Unusual 9-endo-trig-Mode Cyclization

Syntheses of nine-membered oxa-heterocyclic compounds by the application of the intramolecular Heck reaction have been difficult to develop. Herein, we describe the synthesis of this class of compounds through the 9- ENDO- TRIG cyclization and 8- ENDO- TRIG cyclization, respectively - a rare mode of cyclization in the literature.