Direct oxidative coupling of vicinal diols with 2aminonaphthoquinones has been studied for the selective synthesis of benzo[f]indole-4,9-diones at a moderate temperature. In the presence of an environmentally benign iron catalyst, the vicinal diols were oxidized to α-hydroxy carbonyl compounds. Subsequently, 2-amino naphthoquinone reacted with the resultant α-hydroxy carbonyl compound through tandem NÀ C and CÀ C bond formation to afford a vast range of pyrrolonaphthoquinones in remarkable yield. Interestingly, when the 1,2-propanediol was used, the secondary alcohol group was oxidized preferably by resulting in the 2-methyl pyrrolonaphthoquinones as the major regioisomer. The synthetic utility of the current strategy was extended for onestep delivery of natural products, such as 3-methyl-1H-benzo [f]indole-4,9-dione (a secondary metabolite isolated from Goniothalamus tapis Miq. with anti-PAF activity), antibiotic utahmycin B (3-methyl-1H-benzo[f]indole-4,9-dione), cytotoxic avicequinone B and anti-viral FNQ3 (2-methyl-naphtho-[2,3-b]furan-4,9-dione).

A Pd(II)-catalyzed dehydrogenative remote C4−H coupling of indoles with unfunctionalized arenes at room temperature was reported. The weak chelating trifluoroacetyl group at the C3-position served as a directing group for the remote C4−H activation. Arenes with a wide range of substituents were employed as the coupling partner in the dehydrogenative crosscoupling reaction.