Asymmetric Semipinacol Rearrangement Enabled by Copper-Catalyzed Propargylic Alkylation

The merger of two powerful synthetic strategies, i.e., asymmetric semipinacol-type rearrangement and transition-metal-catalyzed propargylic alkylation, has been achieved, delivering a range of enantioenriched cyclo- and heterocyclopentanones with alpha- alkynylated quaternary stereocenters. Such types of products are challenging to obtain using other methods, and their synthetic value has been demonstrated in a variety of further transformations. The work represents a distinctive mode inducing asymmetric 1,2-carbon migration and further expands the scope of propargylic substitution.