Weakly coordinating tert -amide assisted Rh(III)-catalyzed C4-cyanation of indoles: application in photophysical studies.

A rhodium(III)-catalyzed indole C4-selective cyanation is described using the bench-stable, user-friendly electrophilic cyanation agent N -cyano- N -phenyl- p -toluenesulfonamide (NCTS) as a coupling partner. A suitably positioned weakly coordinating tert -amide group was utilized for this site selectivity. The developed protocol proceeded with a broad scope. [Cp*Rh(MeCN) 3 ][SbF 6 ] 2 was found to be an effective Rh(III) catalyst for this transformation. An initial study was carried out to know the photophysical properties of the C4-cyanated indole frameworks.