Highly Diastereo-, α-Regioselective Catalyst-Free Construction of Adjacent Dispirobisoxindoles with Three Contiguous Quaternary Carbon Centers

Abstract

A new methodology was developed for the highly diastereoselective construction of dispirobisoxindole scaffolds via a domino α-regioselective Michael/cyclization reaction sequence of 3-isothiocyanato oxindoles and isatylidene malononitriles under catalyst-free conditions. Complex polycyclic oxindoles featuring two side-by-side oxindole skeletons and three contiguous quaternary carbon centers were synthesized in up to 95% yield and >20:1 dr. This protocol could provide libraries of stereochemically rich small molecules that will help in the search for new bioactive molecules.