Palladium-Catalyzed Direct Arylation-Based Domino Synthesis of Annulated N-Heterocycles Using Alkenyl or (Hetero)Aryl 1,2-Dihalides

摘要

A palladium-catalyzed reaction sequence consisting of an intermolecular animation and an intramolecular direct arylation enabled highly regioselective syntheses of functionalized indoles or carbazoles and proved to be amenable to the use of inexpensive 1,2-dichloroarenes as electrophiles.Because of their ecologically sound and economically attractive nature, direct arylations of (hetero)arenes are attractive alternatives to cross-coupling reactions with stoichiometric amounts of organometallic reagents. Until now, these challenging C-H bond functionalization reactions have predominantly been accomplished with catalysts based on palladium, rhodium, ruthenium or other metals.After pioneering contributions by Ames and Ohta, palladium-catalyzed direct arylations with aryl iodides, triflates, or bromides as electrophiles have proved to be increasingly useful tools for efficient syntheses of heterocycles.