Cyclodimerization of 3-phenacylideneoxindolines with amino esters for the synthesis of dispiro[indoline-3,1′-cyclopentane-3′,3″-indolines]

Triethylamine-promoted domino cyclodimerization reaction of 3-phenacylideneoxindolines with amino ester hydrochlorides in acetonitrile afforded substituted dispiro[ indoline-3,1'-cyclopentane-3',3 "-indolines] in good yields. The relative configuration of the major diastereoisomers was determined by the X-ray diffraction analysis of three single crystal structures.