Visible-light driven acetoxylation and dioxygenation of indoles via electron donor-acceptor complexes
Aditya Paul1, Arunava Sengupta1, Somnath Yadav1
1Department of Chemistry & Chemical Biology, Indian Institute of Technology (ISM), Dhanbad, 826004, Jharkhand, India. somnath@iitism.ac.in.
Abstract:
A photoresponsive electron donor-acceptor (EDA) complex, formed by indole and hypervalent iodine such as diacetoxyiodobenzene (DAIB/PIDA, etc.), was detectable through absorption and emission spectroscopy. Irradiation of the EDA complex with visible light triggered photoinduced single electron transfer (SET) processes that were synthetically useful for the catalyst-free, regioselective acetylation of indoles. The photocatalytic reaction with excess DAIB was also used for the synthesis of isatins. The synthetic protocols were tolerant of a wide variety of substituents on the indole ring, including N-substitutions. DFT and TD-DFT studies were performed to model the excited states of the EDA complex and validate the photoinduced SET mechanism.
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