Palladium-Catalyzed <i>N</i> -Nucleophilic Ring-Opening Reaction of Spiro-vinylcyclopropyl Oxindoles and Synthetic Conversion

A palladium-catalyzed <i>N</i>-nucleophilic ring-opening reaction of spiro-vinylcyclopropyl oxindoles introducing an azido or a substituted amino group into the C3 position has been developed. Using palladium (0) as the catalyst, the racemic spiro-vinylcyclopropyl oxindoles can not only be converted to their chiral diastereoisomers via a stereoisomerization process but also generate a series of azido-substituted oxindole derivatives through the nucleophilic azide addition or be transformed to tertiary amine-substituted oxindoles through a simple ring-opening process. Notably, the azide products can serve as an important synthetic intermediate to successfully convert to other 3-substituted oxindole derivatives and the spiro[furan-3,3'-oxindoles], which exhibit good antitumor activity in vitro, thus demonstrating their potential applications in medicinal chemistry.