Novel preparation of chiral 3,2′-pyrrolidinyl spirooxindole from an enantioselective Michael addition between 3-(diphenylmethylene)-amino-oxindole and acrolein catalyzed by a cinchona alkaloid

A new type of spiro[pyrrolinyl-3,2′-oxindole] scaffolds were effectively prepared from an enantioselective Michael/cyclization between a crucial synthon of 3-(diphenylmethylene)-amino oxindole and acrolein catalyzed by a cinchona alkaloid in up to 99% total yield with up to 99% ee. Those spirooxindole aldehyde imines were reduced to new kinds of prolineamide like spirooxindole chiral amine organocatalysts. The reaction has been successfully scaled up to a gram scale and most typical organocatalysts were further purified up to 99% ee by recrystallization in their hydrochloride salts.