Selective [5 + 1] and [5 + 2] Cycloaddition of Ynamides or Propargyl Esters with Benzo[<i>d</i>]isoxazoles via Gold Catalysis
作者:Wei Xu、Jidong Zhao、Xiangdong Li、Yuanhong Liu
DOI:10.1021/acs.joc.8b02935
日期:2018.12.21
Benzo[d]isoxazoles are found to act as novel nucleophiles to undergo gold-catalyzed [5 + 1] or [5 + 2] cycloaddition reactions with ynamides. The reaction provides a concise and chemoselective access to polysubstituted 2H-benzo[e][1,3]oxazines or benzo[f][1,4]oxazepines. In addition, benzo[d]isoxazoles can also react with gold-carbene intermediates derived from propargyl esters to afford [5 + 1] annulation
发现苯并[ d ]异恶唑可作为新型亲核试剂与金酰胺进行金催化的[5 + 1]或[5 + 2]环加成反应。该反应提供了对多取代的2 H-苯并[ e ] [1,3]恶嗪或苯并[ f ] [1,4]氧杂ze子的简明和化学选择性的途径。另外,苯并[ d ]异恶唑也可以与衍生自炔丙基酯的金卡宾中间体反应,得到[5 +1]环化产物。
Cycloaddition of benzynes and nitrile oxides: synthesis of benzisoxazoles
作者:James A. Crossley、Duncan L. Browne
DOI:10.1016/j.tetlet.2010.02.103
日期:2010.4
A mild and efficient process has been developed for the synthesis of benzisoxazoles through the cycloaddition of benzynes and nitrileoxides. This method allows access to both (hetero)aromatic and alkenyl-substituted benzisoxazoles. Preliminary studies concerning regioselectivity are also reported.
novel, efficient, and facile protocol has been developed for transforming 2-hydroxybenzonitriles and bromides into a range of 3-aryl or alkylsubstituted 1,2-benzisoxazoles in good to excellent yields mediated by PPh3. The electronic and steric effects of bromides on the reaction are discussed. This is the first example to construct a C–C bond and heterocycle in a Barbier–Grignard-type reaction featuring
Key to the procedure is the simultaneous in situ generation of reactive nitrile oxides from arenecarbohydroximoyl chlorides and aryne reactants from benzobis(oxadisilole) or 2,3-naphthoxadisilole. One oxadisilole-fused benzisoxazole is a new precursor of a benzyne formed by a phenyliodination/fluoride-induced elimination protocol. By using this benzyne, cycloadducts were synthesized in good yields. The
A new protocol has been developed for the synthesis of benzo[d]isoxazole through a palladium-catalyzed C–H bond functionalization–[4 + 1] annulation pathway.