Photoinduced Selective Cyclization Cascades of Unactivated N-alkene-Linked Indoles with the Insertion of Sulfur Dioxide and Its Preliminary Application Investigation.

Photoinduced selective cyclization cascades of unactivated N-alkene-linked indoles with the insertion of sulfur dioxide were established, generating diverse exo- or endo-trig-cyclization products with a broad substrate scope in moderate to good yields. The mechanistic study revealed that selective radical addition, cyclization and radical-polar-crossover (RPC) process were involved in this transformation. We next deliverd a preliminary application investigation, and found that 3wj exhibited significant inhibitory effect on B16F10 cells, most showed a significant photophysical property, and some were applied as fluorescent dyes into live-cell imaging.