Divergent Synthesis of Quinazolin-4(3 H )-ones and Tryptanthrins Enabled by a tert -Butyl Hydroperoxide/K 3 PO 4 -Promoted Oxidative Cyclization of Isatins at Room Temperature

A synergetic tert-butyl hydroperoxide/K3PO4-promoted oxidative cyclization has been developed for the facile synthesis of various functionalized quinazolin-4(3H)-ones from commercially available isatins and amidine hydrochlorides at room temperature. The synthetic utility of this strategy was illustrated by the convenient synthesis of tryptanthrin derivatives via a self-dimerization of isatins under the same conditions.