Chiral rhodium(I) complexes activate allenyl tert-cyclobutanols efficiently through enantioselective insertion into a C-C σ bond of the cyclobutane. Ring expansion by this method produced cyclohexenones with quaternary stereogenic centers with excellent enantioselectivity. The catalyst loading can be decreased to just 0.1 mol% in rhodium.
Paul Joseph Dyson, Mingyang Liu, Yelin Hu, Matthias Beller