A cascade reaction for the new and direct synthesis of indolofuroquinoxalines

The 7 H -indolo[3′,2′:4,5]furo[2,3- b ]quinoxaline derivatives are synthesized directly from methyl 2-(2-chloro-1 H -indol-3-yl)-2-oxoacetate or its N -alkyl derivatives under neutral or mildly acidic conditions. This new one-pot methodology was found to be general and greener as it avoids the use of environmentally harmful POCl 3 and strong alkali required for the previously reported method. It is also amenable for scale-up. A cascade reaction has been developed for the direct and one-pot synthesis of 7 H -indolo[3′,2′:4,5]furo[2,3- b ]quinoxaline derivatives.