Sonogashira cross-coupling reactions with heteroaryl halides in the presence of a tetraphosphine-palladium catalyst

Heteroaryl halides undergoes cross-couplings with alkynes in good yields in the presence of PdCl(C₃H₅)]₂/cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as catalyst. A variety of heteroaryl halides such as pyridines, quinolines, a pyrimidine, an indole, a thiophene, or a thiazole have been used successfully. The reaction also tolerates several alkynes such as phenylacetylene and a range of alk-1-ynols. Furthermore, this catalyst can be used at low loading with some substrates.