Highly regioselective Heck reactions of heteroaryl halides with electron-rich olefins in ionic liquid

Palladium-catalyzed Heck reactions of the heteroaryl halides, halopyridines, bromoquinoline and bromothiophenes, with the electron-rich olefins vinyl ethers and allyl alcohol were shown to give essentially only the branched olefins in an imidazolium ionic liquid, whereas in molecular solvents a mixture of regioisomers was formed. The method obviates the need for aryl triflates and stoichiometric inorganic salt additives, providing an easy entry to functionalized heteroaromatics incorporating acetyl and 2-allyl alcohol functionalities.

Graphical abstractThe Heck reactions of heteroaryl halides with the electron-rich olefins vinyl ethers and allyl alcohol afforded essentially only the branched products in an imidazolium ionic liquid, whereas in molecular solvents a mixture of regioisomers was formed.Figure optionsDownload full-size imageDownload as PowerPoint slide