Synthesis of 3,3-disubstituted oxindoles through Pd-catalyzed intramolecular cyanoamidation

The cyanoamidation of olefins was achieved. When N-(2-vinylphenyl)cyanoformamides were treated with palladium catalyst, intramolecular cyanoamidation took place to give corresponding 3,3-disubstituted oxindoles. P(t-Bu)3 showed a remarkable effect on this reaction. When it was used with Pd(dba)2, the reaction was completed in 15 min at 100 °C for many substrates. Furthermore, the enantioselective cyanoamidation was accomplished with Pd(dba)2 and an optically active phosphoramidite to provide optically active 3,3-disubstituted oxindoles. Manipulation of the resulting oxindoles has been studied.