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Photocatalytic Smiles Rearrangement at Remote C(sp3)-H Bonds
Koustav Pal1, Shirshendu Giri1, Manasi Mallick1
1Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India.
Abstract:
A photochemical method enables sequential difluoromethylation and distal Smiles rearrangement at positions C11 and C6 of unactivated alkenes through 1,5-hydrogen atom transfer. This C(sp3)-H activation bypasses proximity constraints, allowing the selective and efficient construction of oxindole frameworks. The organophotocatalyst 4DPNIPN catalyzes the transformation and proceeds via a radical-polar crossover mechanism initiated through oxidative luminescence quenching. The reaction operates under redox-neutral conditions without transition metals, stoichiometric oxidants, or additives. This protocol demonstrates excellent sustainability, broad functional group tolerance, and scalability and represents the first reported approach for synthesizing oxindole via selective distal C(sp3)-H activation.
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