Enantioselective indium(I)-catalyzed [4+2] annulation of alkoxyallenes and β,γ-unsaturated α-keto esters

An indium(i)-chiral phosphoric acid complex was found to catalyze the enantioselective [4 + 2] annulation reaction of ,-unsaturated -keto esters with alkoxyallenes, affording cyclic O,O-acetals in good yields and with high regio- and stereo-selectivities.