Oxidation of p-aminophenols and formal radical cyclization onto benzene rings: formation of benzo-fused nitrogen heterocycles.
p-Iodophenol and its O-MOM-protected ether can be converted into iodoamines 2. These give cross-conjugated ketones 3 on oxidation with hypervalent iodides in the presence of methanol, and the ketones undergo radical cyclization. Exposure of the products to acid or sequential treatment with a Grignard reagent and acid effects rearomatization to produce benzo-fused nitrogen heterocycles 4.
Fletcher
Stephen P
SP
Chemistry Department, University of Alberta, Edmonton, Alberta, Canada T6G 2G2.
Clive
Derrick L J
DL
Peng
Jianbiao
J
Wingert
David A
DA