Palladium on activated carbon: a valuable heterogeneous catalyst for one-pot multi-step synthesis

摘要

Pd on activated carbon(Pd/C)is demonstrated to be active and selective as one single catalyst in a series of one-pot multi-step reactions.The carefully chosen Pd/C catalysts were successfully applied in domino and tandem reactions involving(1)Heck reactions and hydrogenations for the synthesis of(a)dibenzyl and(b)2-styryl-phenylamine,(2)Sonogashira coupling and intramolecular heteroannulation to form indole ring systems,and(3)Heck and Suzuki coupling reactions to produce 4-styryl-biphenyl.Total yields between 72 and 93% could be achieved.All reaction steps were performed with one and the same Pd/C catalyst,solvent,and additives.Temperature and pressure were adjusted as necessary.The order of the different reactions,the consecutive addition of educt(s)and optimization of reaction conditions was found to be crucial.