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.