Direct access to pyrazolo(benzo)thienoquinolines. Highly effective palladium catalysts for the intramolecular C–H heteroarylation of arenes

Abstract

A short and atom-efficient strategy to obtain a series of pyrazolo(benzo)thienoquinolines is developed. Alternative catalytic systems for the key intramolecular direct heteroarylation of arenes are presented and include the first example of C-H (hetero)arylation of (hetero)arenes catalyzed by very low catalyst loadings of a palladium source.