Copper‐Catalyzed Asymmetric Three‐Component Borylstannation: Enantioselective Formation of CSn Bond

In summary, a first copper‐catalyzed synthesis of α‐aryl‐β‐borylstannane compounds was accomplished through three‐component borylstannation of aryl‐substituted alkenes. In the exploration of an asymmetric variant, chiral sulfinylphosphine ligands proved advantageous in controlling stereochemistry of B?Cu addition and in promoting transmetalation of enantioenriched alkyl?Cu species. The stereochemical outcome supported a sequential syn‐borylcupration and configuration‐retentive transmetalation mechanism. Moreover, α‐chiral β‐borylstannanes were easily transformed into a diverse array of secondary alkylstannanes and triarylethane with high enantiomeric purity. The applications of chiral sulfinylphosphine ligands to other tandem Cu?B addition reactions are currently under investigation in our group.