Seven examples of the novel 4H-furo [3, 4-b] indole ring system (3-9)-a stable, synthetic analogue of indole-2, 3-quinodimethane-have been synthesized in 6-8 steps from simple indoles in overall yields of 21-28%. These 4H-furo [3, 4-b] indoles undergo Diels-Alder reactions with several dienophiles (dimethyl acetylenedicarboxylate, N-phenylmaleimide, benzyne), including ethyl acrylate, which reacts regiospecifically with furoindole 4 to afford ...
