Synthesis and Evaluation of N-Diaminophosphoryl Aminothioureas as Bifunctional Catalysts for Vinylogous Aldol Reactions of Isatins and 2(3H)-Furanones

The organocatalytic asymmetric direct vinylogous aldol reaction of N-methylisatins 1 and γ-butenolides 2 to provide 3-hydroxy-2-oxindole derivatives 3 was investigated. A series of N-diaminophosphoryl aminothiourea catalysts 4 was synthesized, and their utility for the stereoselective formation of 3 was examined.