Compounds containing 4H-1,3-benzo-xazine core usually possess characteristic features and have been applied in the fields of organic synthesis, pharmaceutical research, materials science and bioscience. Here we reported convenient and direct access to 4H-1,3- benzo-xazines and their derivatives through intramolecular cyclization of olefinic amides or ureas with good to excellent yields in the presence of TMSOTf. The properties (mild conditions, metal or additives-free, wide substrate scope and functional group tolerance) of the process made it a promising strategy to synthesize various benzo-xazines and their derivatives.

中文翻译：

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路易斯酸介导的4H-1,3-苯并恶嗪及其衍生物4,5-二氢-1,3-苯并恶嗪的高效合成

含有4H-1,3-苯并恶嗪核心的化合物通常具有特征性特征，并已应用于有机合成，药物研究，材料科学和生物科学领域。在这里，我们报道了在存在TMSOTf的情况下，通过分子内环化烯烃酰胺或脲的方法，可以方便，直接地获得4H-1,3-苯并恶嗪及其衍生物。该方法的性质（温和的条件，无金属或无添加剂，广泛的底物范围和官能团耐受性）使其成为合成各种苯并恶嗪及其衍生物的有前途的策略。