Regiospecific Palladium-Catalyzed Cross-Coupling Reactions Using the Operational Equivalent of 1,3-Dilithiopropyne

Abstract

A regiospecific palladium-catalyzed cross-coupling reaction using the operational equivalent of the dianion 1,3-dilithiopropyne, with aromatic iodides is reported. This reaction gives high yields of 1-propyn-1-yl-benzenes and 2-(propyn-1-yl)thiophenes in the presence of catalytic amounts of palladium(0) or (II) and stoichiometric amounts of copper iodide. No terminal alkyne or allene isomers were detected. Reaction conditions were very mild and several functional groups were tolerated.

Markovnikov versus anti‐Markovnikov addition and C–H activation: Pd–Cu synergistic catalysis

“…In 1975, Cassar and Heck revealed a palladium‐catalyzed cross‐coupling reaction of acetylides, produced inside the reaction mixture terminal alkynes and sodium methoxide or trimethylamine (TMA), with aryl halides. [ 6–9 ] Chemists discovered that the application of copper co‐catalyst shows a critical quickening impact within sight of triethylamine almost at the same time. [ 10,11 ] This well‐known protocol, which is called, Sonogashira or Sonogashira–Hagihara coupling/reaction, is at present one of the best applicable methods for alkynylation of 1‐alkenyl halide and aryl halides.…”