Copper-Catalyzed Enantioselective Hydrocupration of Cyclic Allenol Esters

Keywords

copper - enantioselective - axial chirality - allenes

Significance

An enantioselective copper-catalyzed synthesis of axially chiral alkylidenecycloalkanes from symmetric acyl allenols is reported. The reaction is also amenable to borylcupration and silylcupration (not shown here). The copper first undergoes hydrocupration with the allene resulting in an allylic copper species. This species then undergoes a β-oxygen elimination to generate the product. The active catalyst is then regenerated via σ-bond metathesis with PhSiH₃.

Comment

The desymmetrization of the meso starting materials to generate axially chiral products is highly efficient, leading to enantioselectivities of up to 98 % and yields of up to 96 %. Various heterocycles, aryl halides, and ring sizes were amenable to the reaction. The authors were also able to derivatize the diene products in various ways.