New ligands for a general palladium-catalyzed amination of aryl and heteroaryl chlorides

The synthesis and application of monodentate N-substituted heteroarylphosphines is described. In general, the ligands are conveniently prepared by selective metallation at the 2-position of the respective N-substituted heterocycle (pyrrole, indole) by using n-butyllithium/tetramethylethylenedi-amine (TMEDA) followed by quenching with dialkyl- or diarylchlorophos-phines. Of the different ligands prepared, the new dialkyl-2-(N-arylindolyl)phosphines (cat CX-ium(R) P) perform excellently in the palladium-catalyzed amination of aryl and hetero-aryl chlorides. Coupling of both activated and deactivated chloroarenes proceeds under mild conditions (room temperature to 60degreesC). By using optimized conditions remarkable catalyst productivity (total turnover number, TON, up to 8000) and activity (turnover frequency, TOF=14000 h(-1) at 75% conversion) are observed.