Catalyst-free photoarylation of 2-aryl-2H-indazoles by carbon-iodine bond activation
Ram Prasanna1,2, Swarnayu Banik3,2, Chidrawar Ajay3,2
1Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad - 500007, India.
Abstract:
A photocatalyst-free visible-light induced arylation of 2-aryl-2H-indazoles with aryl iodides has been developed for the first time to produce 3,2-diaryl-2H-indazoles in good to moderate yields. In this transformation, potassium tert-butoxide acts as an activator of the C-I bond and also as a scavenger of in situ generated HI in the reaction. This method exhibits high functional group tolerance with a wide substrate scope and it has been successfully applied to the synthesis of liver X receptor agonists and also for fluorescent probes. This is the first report on the photoarylation of 2-arylindazoles at the C3-position with aryl iodides under catalyst-free conditions.
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