A Catalyst‐Free Self‐Catalyzed [3+2] Cycloaddition Reaction of 3‐Isothiocyanato Oxindoles and Vinylpyridines.

A catalyst‐free self‐catalyzed [3+2] cycloaddition reaction of 3‐isothiocyanato oxindoles with vinylpyridines has been established, affording the desired products in high yields (up to 97 %) with moderate to good diastereoselectivities (up to 11:1) under mild conditions. The reaction mechanism has been investigated by control experiments, DFT calculations of pKa values and the kinetic studies, revealing that this reaction featured the mutual activation between 3‐isothiocyanato oxindole and vinylpyridine to generate the reactive species. Furthermore, these products could be easily transformed into the corresponding methylated and hydroxylated products under basic conditions. [ABSTRACT FROM AUTHOR]