Diastereoselective and Enantioselective Alleno-aldol Reaction of Allenoates with Isatins to Synthesis of Carbinol Allenoates Catalyzed by Gold

A new asymmetric alleno-aldol addition of allenic esters has been developed that allows the formation of trisubstituted and tetrasubstituted carbinol allenoates diastereoselectively and enantioselectively. The nucleophilic additions of achiral and racemic allenates to isatins proceed well in the presence of AuCl3 and chiral N,N′-dioxide under mild reaction conditions. The results reported herein represent the first example of metal complex promoted γ-selective asymmetric addition of allenic esters to carbonyl compounds.