Synthesis and Characterization of New 3,4-Dihydro-2H-benzo- and Naphtho-1,3-oxazine Derivatives
作者:A.U. Garin Gabbas、M.B. Ahmad、N. Zainuddin、N.A. Ibrahim
DOI:10.14233/ajchem.2016.19666
日期:——
New 1,3-benzoxazine and naphthoxazine monomers were synthesized using a modified step-wise technique in which formaldehyde was replaced with methylene bromide for ring-closure reaction in the last synthetic step. Salicylaldehyde and 2-hydroxy-1-naphthaldehyde were used as the aromatic aldehydes and 4-fluoroaniline, 4-butylaniline, hexamethylenediamine, p-phenylenediamine and 2-aminothiazole were used as the primary amines. Condensation of the aromatic aldehydes and the aromatic primary amines in absolute ethanol gives imine compounds which on reduction with sodium borohydride in methanol give 2-hydroxybenzylamines/2-hydroxynaphthylamines. Ring-closure reaction between 2-hydroxybenzylamines/2-hydroxynaphthylamines and methylene bromide in absolute ethanol gives the 1,3-benzoxazines and naphthoxazines in good yields. The structures of the new 1,3-benzoxazine and naphthoxazine monomers were confirmed by FT-IR, 1H NMR and 13C NMR spectral analysis, Mass spectroscopy (GC-MS) and elemental analysis. The mass spectrum of the synthesized compounds showed molecular ion peaks centered at m/z 229, 218, 316, 317, 444 and 268 which are equivalent to the molecular weights of the new synthesized compounds a, b, c, d, e and f, respectively. Results of elemental analysis also confirm the calculated result to be in agreement with the experimental result.
采用改良的逐步合成技术,其中在最后的合成步骤中,使用亚甲基溴代替甲醛进行环化反应,合成了新的1,3-苯并噁嗪和萘并噁嗪单体。水杨醛和2-羟基-1-萘醛用作芳香醛,4-氟苯胺、4-丁基苯胺、己二胺、对苯二胺和2-氨基噻唑用作一级胺。在无水乙醇中缩合芳香醛和芳香一级胺得到亚胺化合物,用硼氢化钠在甲醇中还原得到2-羟基苄胺/2-羟基萘胺。2-羟基苄胺/2-羟基萘胺与亚甲基溴在无水乙醇中的环化反应以良好产率得到1,3-苯并噁嗪和萘并噁嗪。新1,3-苯并噁嗪和萘并噁嗪单体的结构通过FT-IR、1H NMR和13C NMR光谱分析、质谱(GC-MS)和元素分析得到确认。合成的化合物的质谱显示出以m/z 229、218、316、317、444和268为中心的分子离子峰,分别相当于新合成化合物a、b、c、d、e和f的分子量。元素分析结果也确认计算结果与实验结果一致。