Organocatalytic asymmetric synthesis of dihydrofuran-spirooxindoles from benzylidene malononitriles and dioxindoles.

The first organocatalytic enantioselective synthesis of dihydrofuran-spirooxindoles having a linkage at the 2-position of the dihydrofuran motif has been developed. Dioxindoles and benzylidene malononitriles were employed in this method. The desired spirooxindole products were obtained via a Michael reaction followed by a Pinner reaction and isomerization and good to high yields with moderate diastereo and good to high enantioselectivities were observed.