Perfluoro-tagged, phosphine-free palladium nanoparticles supported on silica gel: application to alkynylation of aryl halides, Suzuki-Miyaura cross-coupling, and Heck reactions under aerobic conditions

The utilization of perfluoro-tagged palladium nanoparticles immobilized on fluorous silica gel through fluorous-fluorous interactions (Pd-np-A/FSG) or through covalent bonding to silica gel (Pd-np-B) in the alkynylation of aryl halides, in the Suzuki-Miyaura cross-coupling, as well as in the Heck reaction between methyl acrylate and aryl iodides is described. The reactions are carried out under aerobic and phosphine-free conditions with excellent to quantitative product yields in each case. The catalysts are easily recovered and reused several times without significant loss of activity. The alkynylation of aryl halides (under copper-free conditions) and the Suzuki-Miyaura cross-coupling are carried out in water. The Heck reaction of methyl acrylate with aryl iodides is best performed in MeCN. The utilization of Pd-np-B in the synthesis of 2,3-disubstituted indoles from 2-(alkynyl) trifluoroacetanilides and aryl halides is also reported.