Enantioselective Organocatalytic Addition of Nitroalkanes to Oxindolylideneindolenines for the Construction of Chiral 3,3-Disubstituted Oxindoles

An enantioselective organocatalytic addition of nitroalkanes to oxindolylideneindolenines in the presence of bifunctional organocatalysts has been established to provide an efficient entry to 3,3-disubstituted oxindole derivatives in high yields and with excellent enantioselectivities. The transformation has been applied to the preparation of the key intermediate for a formal total synthesis of (+)-gliocladin C.