Photo-Promoted Construction of 3‑Spiro-2-sulfonylimino-indoline Skeletons via Cascade Reaction

The cascade reaction of 3-diazo-2-sulfonyliminoindolines
and N-methoxymethyl-N-[(trimethylsilyl)methyl]benzylamines
generates 2-sulfonylimino-1′,3′,4′,6′-tetrahydro-2’H-spiro[indoline-3,5′-pyrimidine] and spiro[indoline-3,3′-pyrrolidine]
derivatives simultaneously under the catalysis of TFA and blue light
irradiation. Their formation mechanisms were proposed on the basis
of isotope-labeled experiments and HRMS analysis of the controlled
experiment mixture, showing new reaction pathways. The current reaction
provides a new strategy for the synthesis of biologically important
spiro[indoline-3,3′-pyrrolidine]-2-one derivatives.