Transition-Metal-Free Synthesis of Fused Quinazolinones by Oxidative Cyclization of -Pyridylindoles.

An unprecedented synthesis of fused quinazolinones from -pyridylindoles under oxidative conditions using a combination of (diacetoxyiodo)benzene and KSO is reported. The reaction is metal-free, has a broad substrate scope, is operationally simple with short reaction time, and provides 11-pyrido[2,1-]quinazolin-11-one derivatives in moderate to high yields. It is believed to proceed via an in situ generated 2-hydroxy-1-(pyridin-2-yl)indolin-3-one as the key reaction intermediate, which undergoes a C-C bond cleavage to produce an electrophilic C-3 site in -pyridyl indole. Subsequent nucleophilic attack by pyridyl nitrogen results in its cyclization.