PyBidine-Ni(OAc)2-Catalyzed Michael/AIdoI Reaction of Methyleneindolinones and Thiosalicylaldehydes for Stereochemically Divergent Thiochromanyl-spirooxindoles

(S,S)-Diphenylethylenediamine-derived bis(imidazolidine)pyridine (PyBidine)-Ni(OAc)(2) complex catalyzed the asymmetric Michael/aldol reaction of methyleneindolinone and thiosalicylaldehyde to produce (2'R,3S,4'R)-thiochromanyl-spirooxindole having three contiguous stereogenic centers.