Nigel Derek Arthur Walshe

On the [42]Cycloaddition Approach to Indolo[2,3-a]carbazoles

Abstract 2,2′-Biindolyl 9 reacts with electron-deficient dienophiles at 100–110 °C to give low to moderate yields of Michael addition and formal [42]cycloaddition products, with the former predominant; the products derived from 9 and 2-(phenylsulphinyl)maleimides 14 and 15 undergo in situ elimination of benzenesulphenic acid, leading to 2,2′-biindolylsubstituted maleimides which can be efficiently photocyclised into indolo[2,3-a]carbazoles.