Double Arylation of Diynes and Alkynylation of Functionalized Heteroaryl Halides by a Practical Heck Reaction in an Ionic Liquid

Abstract

The efficient palladium-catalyzed alkynylation of electron-rich bromoheteroarenes, incorporating deactivating electrondonating methyl and methoxy groups, and the (hetero)arylation of diynes, take place in the imidazolium ionic liquid [BMIM][BF 4 ], as a highly polar non-volatile solvent. This method may constitute a sustainable alternative to classical solvents such as dioxane, DMF, NMP, or DMAc. New enynes are formed in the presence of a system encompassing a copper-free palladium catalyst, triphenylphosphine as ligand, and various inexpensive bases. The enyne molecules reported are selectively synthesized in high yields and are mostly unprecedented.

Uncommon perspectives in palladium- and copper-catalysed arylation and heteroarylation of terminal alkynes following Heck or Sonogashira protocols: Interactions copper/ligand, formation of diynes, reaction and processes in ionic liquids

“…With regards to the relevant results obtained in the arylation of terminal alkynes in an ionic liquid, we investigated the double arylation of terminal diynes by using the same methodology (Scheme 8) [36]. One objective was to examine whether a first arylation of the terminal diyne would modify the course of a second arylation on this substrate.…”