Highly diastereoselective synthesis of dispiro[1,4-dithiane/dithiepane]bisoxindoles via Stevens rearrangement

Synthesis of dispiro[1,4-dithianes/dithiepanes]bisoxindoles from the reaction of 3-diazo-2-oxindoles and spiro-1,3-dithiolaneoxindole or -1,3-dithianeoxindole derivatives in the presence of rhodium(II) acetate dimer as a catalyst was demonstrated under mild conditions in a highly diastereoselective manner. These dispiro-compounds were obtained via intermolecular sulfonium ylides and followed by Stevens rearrangement.