Diazatruxenes from the Condensation Reaction of Indoles with Ninhydrin

The reaction of indoles with ninhydrin has been reported to provide only 1:1 condensation products (cf. A or 8 ) that show good antioxidant and anti‐inflammatory activity. In the present work, our synthetic challenge for the synthesis of innovative, highly substituted tetra‐indole indanes of type 1 via a 4:1 condensation reaction in acetic acid gave two unexpected new products, the diazatruxene derivatives 3 and 4 . The novel structures have been characterized by their analytical and spectral data including 1D‐ and 2D‐NMR. With 5‐chloroindole, only the known 1:1 reaction.