The existing literature method for the conversion of the readily available (±)-vincadifformine (2) into the key intermediate 16-hydroxyindolenine (3) showed that the latter compound is particularly unstable [7, 8]. Similarly, photo-oxygenation [9] of 2 in the presence of Rose Bengal and sodium thiosulphate as reducing agent to give 16-hydroxyindolenine (3) resulted in low yields of the desired compound. The other product was mainly recovered starting material. This is ...
