DMAP-Catalyzed Cyclization of Schiff Bases with α -halo ketones: Synthesis of 1,4-Benzoxazines

We demonstrate that 1,4-benzoxazines can be efficiently synthesized via using 4-dimethylaminopyridine (DMAP) as a catalyst. We found that the DMAP catalyst can successfully promote the incorporation of the activated carbon atoms of α -halo ketones into the Schiff bases. The 1,4-benzoxazines can be synthesized via formation of C-O and C-C bond in high yield, employing the DMAP as the catalyst, α -halo ketones and phenolic Schiff bases as the reactants. Furthermore, a possible mechanism is proposed. This work provides a simple and efficient route to prepare the 1,4-benzoxazines.