Hydrogen‐Borrowing‐Based Methods for the Construction of Quaternary Stereocentres

Compounds containing quaternary stereocentres are a valuable motif in biologically active compounds. Herein we present our strategy to utilise the hydrogen borrowing manifold to access α‐quaternary ketones via a tandem acceptorless dehydrogenation‐cyclisation cascade. This new application of the methodology results in the formation of five‐ and six‐membered carbocycles with a high degree of diastereoselectivity. Interestingly, benzylic alcohol substrates behaved anomalously and eliminated sulfinate in situ to give a set of rearranged α‐quaternary ketone products.