Priyanka Nath, Ariful Islam, Mohit L Deb, Pranjal K Baruah
An oxidative rearrangement of 3,3'-bisindolylmethanes has been developed for the direct synthesis of 2,2'-biindoles using PdCl2 and Cu(OAc)2·H2O. The transformation proceeds through an unusual sequence of intramolecular C-C bond formation followed by C-C bond cleavage. Cu(OAc)2 acts as a co-oxidant and likely contributes beyond simple reoxidation. The method exhibits broad functional-group tolerance and provides practical access to diverse 2,2'-biindole derivatives, revealing bisindolylmethanes as latent synthons for biindole construction.