Green Synthesis of Tetracyclic Quinazolinones Based on Iodine‐Catalyzed Oxidative Desulfurative Cyclization in Water

Green method for the synthesis of 12 H ‐benzo[4,5]oxazolo[2,3‐ b ]quinazolin‐12‐one derivatives, a rare class of tetracyclic heterocycles, has been realized. Reaction of methyl isothiocyanatobenzoates with 2‐aminophenols formed 3‐(2‐Hydroxyphenyl)‐2‐thioxo‐2,3‐dihydroquinazolin‐4(1 H )‐ones, which were treated in situ with a catalytic amount of iodine in the presence of oxidant and base to provide the desired 12 H ‐benzo[4,5]oxazolo[2,3‐ b ]quinazolin‐12‐ones in good yields in water as a green solvent. A range of functional groups has been tolerated through the transformations.