An Asymmetric, Catalytic (4+3) Cycloaddition Reaction of Cyclopentenyl Oxyallylic Cations

Treatment of 2-tosyloxycyclopentanone with substituted furans in the presence of a chiral amino alcohol catalyst and K2HPO4 results in the formation of (4 + 3) cycloaddition products with enantioselectivities that exceed 90% in certain cases.