Asymmetric Chlorination/Ring Expansion for the Synthesis of α-Quaternary Cycloalkanones

A highly enantioselective chlorination/ring expansion cascade for the construction of cycloalkanones with an all-carbon quaternary center was realized (up to 97% ee). Oxa-cyclobutanol substrates were employed for the first time in the ring expansion reactions, affording the functionalized dihydrofuranones in excellent enantioselectivity.