Photo-Promoted\nConstruction of 3‑Spiro-2-sulfonylimino-indoline\nSkeletons via Cascade Reaction

The cascade reaction of 3-diazo-2-sulfonyliminoindolines\nand <i>N</i>-methoxymethyl-<i>N</i>-[(trimethylsilyl)methyl]benzylamines\ngenerates 2-sulfonylimino-1′,3′,4′,6′-tetrahydro-2’<i>H</i>-spiro[indoline-3,5′-pyrimidine] and spiro[indoline-3,3′-pyrrolidine]\nderivatives simultaneously under the catalysis of TFA and blue light\nirradiation. Their formation mechanisms were proposed on the basis\nof isotope-labeled experiments and HRMS analysis of the controlled\nexperiment mixture, showing new reaction pathways. The current reaction\nprovides a new strategy for the synthesis of biologically important\nspiro[indoline-3,3′-pyrrolidine]-2-one derivatives.