Compounds of general formulae I and II, in which R5 is hydrogen, may be converted to derivatives where one or two R5 groups may be added by treatment of a fused pyrrolocarbazole-6-one derivative with one equivalent or an excess of a strong base (e.g., hydrides, alkoxides, hydroxides of alkali or alkaline earth metals, or of organo-lithium compounds) with R5 L in which L is a leaving group such as