Concise synthesis and characterization of unsymmetric 1,3-benzoxazines by tandem reactions

A new synthetic protocol for the preparation of unsymmetric 1,3-bisbenzoxazines using the combination of three-step synthesis and classical one-step benzoxazine synthesis strategies is described. For this purpose, 4-hydroxyphenylaminomethyl phenol (HPAMP) is synthesized as the intermediate and reacted with two different aliphatic amines to yield the desired unsymmetric bisbenzoxazines. The structures of the intermediates and products are confirmed by FT-IR and 1H NMR spectral analysis. Curing behaviors of the bisbenzoxazines are studied by differential scanning calorimetry (DSC).