Palladium-Catalyzed Sonogashira-Coupling Conjoined C?H Activation: A Regioselective Tandem Strategy to Access Indolo- and Pyrrolo[1,2?a]quinolines

摘要

An operationally simple approach for the regioselectiventandem synthesis of indolo[1,2-a]quinolines 4a−v andnpyrrolo[1,2-a]quinolines 5a−k from 1-(2-bromophenyl)-1Hindolepyrrole/imidazole 1a−c, 2a,b by the palladium-catalyzednsequential C−C bond formation is described. The developednapproach involves the palladium-catalyzed Sonogashira couplingnfollowed by the intramolecular C−C bond formation via C−Hnactivation, which leads to the formation of 6-endo-dig cyclizednproduct. This synthetic methodology accommodates wide functionalngroup variation on alkyne, which proves to be advantageousnfor the structural and biological activity assessments.