Mechanism-controlled regioselective synthesis of indolyl benzo[b]carbazoles

Benzo[b]carbazoles can be synthesised readily and in good yields from the c ombination of 2,3-unsubstituted indoles and o-phthaldialdehyde in the prese nce of acid catalysts. Use of phosphoryl chloride in chloroform gives rapid reactions and yields 11-(3-indolyl)benzo[b]carbazoles, whereas the use of p-toluenesulfonic acid in methanol gives slow reactions and yields the isom eric 6-(3-indolyl)benzo[b]carbazoles. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.