Photo-Induced N-N Coupling of O-Nitrobenzyl Alcohols and Indolines to Give N-Aryl-1-amino Indoles.

A novel method to synthesize N-aryl-1-amino indoles was established by the photoinduced N-N coupling reaction. This protocol is by treatment of o-nitrobenzyl alcohols and indolines in the presence of TEAI and acetic acid with a 24 W ultraviolet (UV) light-emitting diode (LED) (385-405 nm) irradiation. The products bearing an aldehyde group can be further transformed to fluorescent probes based on Rhodamine 6G derivative 11, which shows a high specificity and sensitivity for Fe3+.