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A palladium-catalyzed coupling between aryl halides and monocyclopropanated pyrroles or furans has been developed, leading to valuable six-membered N- and O-heterocycles. As the key step, a selective cleavage of the non-activated endocyclic C?C bond of the 2-heterobicyclo-[3.1.0]hexane framework is achieved. The developed method offers access to highly functionalized piperidines, pyridines, and pyrans that are challenging to access by traditional methods.

Organozinc compounds of the type R1—Ar1—ZnY (1) can be reacted with different functionalized aryl halides R2—Ar2—X (2) in the presence of catalytic amounts of Ni or Fe in a polar solvent or solvent mixture to form polyfunctional biaryles of the type R1—Ar1—Ar2—R2 (3). Organozinc compounds of the type (1) can be represented by the transmetallation reaction of functionalized aryl magnesium halides or lithium aryl compounds with e.g. ZnBr2.

A combination of diethyl phosphite-DMAP and Ni(II) salts forms a very effective catalytic system for the cross-coupling reactions of arylzinc halides with aryl, heteroaryl, and alkenyl bromides, chlorides, triflates, and nonaflates. The choice of solvent is quite important and the mixture of THF-N-ethylpyrrolidinone (NEP) (8:1) was found to be optimal. The reaction usually requires only 0.05 mol % of NiCl2 or Ni(acac)2 as catalyst and proceeds at room temperature within 1-48 h.