Dehydrogenative Aromatic Ring Fusion for Carbazole Synthesis via C-C/C-N Bond Formation and Alkyl Migration
1School of Chemical Sciences, National Institute of Science Education and Research (NISER) Bhubaneswar , HBNI, P.O. Bhimpur-Padanpur, Via Jatni, Khurda 752050, Odisha, India.
Abstract:
An intermolecular dehydrogenative annulation (IDA) for carbazole synthesis via sequential C-C/C-N bond formation with a selective alkyl group migration is reported. Using the hypervalent iodine(III) reagent PhI(OAc)2 (PIDA), in a one-pot operation, up to five C(sp2)-H bonds, one N(sp3)-H bond functionalization, and one alkyl (Me, Et) group migration could all be achieved from non-prefunctionalized 1,3,5-trialkylbenzenes and anilides under ambient laboratory conditions. Mechanistically, it is shown that PIDA reacts with anilides to generate a nitrenium ion or an equivalent carbenium ion which influences the second aromatic ring to be activated for C-C/C-N bond formation. Strategically, regioselective fusion of arenes to anilides is described.
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