Intramolecular addition of acyldiazenecarboxylates onto double bonds in the synthesis of heterocycles
作者:José V. Prata、Dina-Telma S. Clemente、Sundaresan Prabhakar、Ana M. Lobo、Isabel Mourato (in part)、Paula S. Branco (in part)
DOI:10.1039/b110414d
日期:2002.2.6
Appropriate aryl-substituted unsymmetrical azodicarbonyl compounds, generated from bishydrazides by oxidation, undergo intramolecular cyclisations to furnish a variety of useful heterocycles such as N-substituted oxindoles, carbostyrils, benzazepinones, benzazocinones, benzimidazolones, benzoxazinones and pyrazolones in varying degrees of efficiency. Methods are described to remove the N-acyl groups from the heteroaromatic compounds. Under mildly acidic conditions where equal opportunities are available for an ipso or a normal cyclisation it is the former process that occurs preferentially. Evidence is presented in favour of a C-to-C migration in the ipso product for the formation of a methoxy-substituted carbostyril derivative. One of the spiro substances is shown to participate in dienone–phenol rearrangement to provide the corresponding quinolone–phenol in high yield.
适当的芳基取代的不对称二羧肼化合物通过氧化从双肼酰胺生成,发生分子内环化,生成各种有用的杂环化合物,如N-取代的氧杂吲哚、羧基醇、苯并氮杂哌啶、苯并氮杂呋喃、苯并咪唑酮、苯并氧杂噁唑和吡唑酮,效率各不相同。文中描述了去除杂芳香化合物中N-酰基基团的方法。在弱酸性条件下,当存在相等机会进行ipso或正常环化时,前者过程优先发生。证据支持在ipso产物中发生C到C的迁移,用于形成甲氧基取代的羧基醇衍生物。显示出某个螺旋物质参与二烯酮–酚重排,以高产率生成相应的喹啉–酚。