Dimethylzinc-Initiated Radical Coupling of [beta]-Bromostyrenes with Ethers and Amines

A new coupling reaction has been developed in which [beta]-bromostyrenes react with ethers and tertiary amines to introduce the styryl group in the [alpha]-position. The transformation is mediated by Me2Zn/O2 with 10% MnCl2 and is believed to proceed by a radical addition-elimination mechanism. The ether and the amine are employed as solvent and the coupling takes place through the most stable [alpha] radical for unsymmetrical substrates. The products are obtained in moderate to good yields as the pure E isomers. The coupling can be achieved with a range of smaller cyclic and acyclic ethers/amines as well as various substituted [beta]-bromostyrenes.