Stereoselective Access to Alkylidenecyclobutanes through γ-Selective Cross-Coupling Strategies

Alkylidenecyclobutanes (ACBs) containing all carbon quaternary stereocenters were simply and efficiently synthesized by combining boron-homologation and gamma-selective cross-coupling strategies. This unique sequence led to excellent regio- and diastereoselectivities in the generation of targeted four-membered rings with up to 99% enantiomeric excess using chiral substrates. In addition to the original synthesis of ACBs, the first asymmetric catalytic formation of quaternary stereocenters based on gamma-selective cross-coupling reactions is finally shown.