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Intramolecular Dehydrogenative Coupling of sp2 C–H and sp3 C–H Bonds: An Expeditious Route to 2‑Oxindoles

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journal contribution
posted on 07.12.2012, 00:00 by Santanu Ghosh, Subhadip De, Badrinath N. Kakde, Subhajit Bhunia, Amit Adhikary, Alakesh Bisai
An intramolecular-dehydrogenative-coupling (IDC) using “transition-metal-free” oxidation conditions has been achieved to synthesize a variety of 2-oxindoles bearing an all-carbon quaternary stereogenic center at the benzylic position. The methodology involves a one-pot C-alkylation of β-N-arylamido esters (3, 6) with alkyl halides using potassium tert-butoxide concomitant with a dehydrogenative coupling. A radical-mediated pathway has been tentatively proposed for the oxidative process.