Gold(I)-Catalyzed Enantioselective Ring Expansion of Allenylcyclopropanols

The asymmetric gold(I)-catalyzed ring expansion of 1-allenylcyclopropanols is described. The method provides synthetically valuable cyclobutanones with a vinyl-substituted quaternary stereogenic center in high enantioselectivities and yields. The method shows a broad substrate scope, tolerating protected alcohols and amines, alkenes, unsaturated esters, and acetals. The reaction is easily adjustable to large-scale synthesis, leading to product formation without significant loss of selectivity or yield with only 0.5 mol% catalyst loading.