Catalytic efficiency of a new tridentate ferrocenyl phosphine auxiliary:: Sonogashira cross-coupling reactions of alkynes with aryl bromides and chlorides at low catalyst loadings of 10-1 to 10-4 Mol %

The catalytic activity in Sonogashira cross-coupling reactions of alkynes with a variety of aryl halides (including chlorides) using a multidentate ferrocenyl phosphine is presented. The novel mixed ferrocenyl aryl/alkyl triphosphine is thermally stable and insensitive to air or moisture, and its robustness allows aryl alkynylation at 10(-1) to 10(-4) mol% catalyst loadings with TONs up to 250000. Copper-free coupling using phenylacetylene is also accessible in good yield.