In the present work, homonuclear coordination complex including Zn (II) and N-hexadecylimidazole ligand was used for the first time as a highly efficient homogeneous neutral organocatalyst for the synthesis of 3,4-dihydro-2H-1,3-benzoxazine monomers. Therefore, N-alkyl or N-aryl substituted, both mono-benzoxazine and bis-benzoxazine, were successfully synthesized (21 examples) via Mannich-type condensation reactions. Effortlessly obtaining the pure product with high yields and the short reaction time makes this method more useful and advantageous than the common existing benzoxazine synthesis methods.