3-Nitro-2H-chromenes in [3+2] cycloaddition reaction with azomethine ylides derived from N-unsubstituted α-amino acids and isatins: regio- and stereoselective synthesis of spirochromeno[3,4-c]pyrrolidines

A regio- and stereoselective method was developed for the synthesis of tetrahydro-4H-spiro[chromeno[3,4-c]pyrrole-1,3'-indolin]-2'-ones in 72−96% yields, using a three-component reaction of 3-nitro-2-trifluoromethyl- and 3-nitro-2-phenyl-2H-chromenes with azomethine ylides that were generated in situ from N-unsubstituted α-amino acids and isatins.