Iodine-Catalyzed C–H Amidation and Imination at the 2α-Position of 2,3-Disubstituted Indoles with Chloramine Salts

A novel iodine-catalyzed amidation
and imination at the 2α-position
of 2,3-disubstituted indoles in the presence of chloramine salts with
high regioselectivity has been achieved. The protocol is applicable
to a wide range of substrates to deliver the corresponding 2α-nitrogen-containing
indole derivatives. Furthermore, to demonstrate the synthetic value
of this established transformation, a concise assembly of the bridged
tetracyclic framework of akuammiline alkaloids from the 2α-amidated
product has been accomplished in five steps.