Stereoselective 1,3-Cyclotelomerization of Butadiene with Dienophiles under Nickel Catalysis

The discovery of new chemoselectivity with readily accessible chemicals is important to expand the reaction space for modern chemistry. For dienes and dienophiles, most people will naturally use them to carry out the classic Diels-Alder reaction to construct six-membered cyclic compounds. Here, we demonstrated a chemoselective coupling of butadiene with dienophiles through a stereoselective 1,3-cyclotelomerization. By utilizing robust Ni/IPr catalysis, valuable bicyclic products were created with high regio- and chemoselectivities under mild conditions. Asymmetric cyclotelomerization enabled by chiral NHC ligand was also performed, generating enantioenriched bicyclic compounds. Mechanistic studies reveal that the reaction might start with oxidative cyclometallation between two molecules of 1,3-diene and Ni(0) species, which then undergoes [3+2]-cycloaddition via an electron transfer process. The products can undergo a variety of intricate transformations, which emphasizes the potential applications of this strategy. It is hoped that the discovery of this protocol will further inspire people to rethink the classic organic reactions.