Synthesis of 5<i>H</i>-chromeno[3,4-<i>b</i>]pyridines <i>via</i> DABCO-catalyzed [3 + 3] annulation of 3-nitro-2<i>H</i>-chromenes and allenoates
作者:Maria I. L. Soares、Clara S. B. Gomes、M. Conceição Oliveira、Joaquim Marçalo、Teresa M. V. D. Pinho e Melo
DOI:10.1039/d1ob01130h
日期:——
The DABCO-catalyzed [3 + 3] annulation between 3-nitro-2H-chromenes and benzyl 2,3-butadienoate has been developed as a route to 5H-chromeno[3,4-b]pyridine derivatives. Under optimal reaction conditions, 5H-chromeno[3,4-b]pyridines incorporating two allenoate units were obtained in moderate to good yields (30–76%). The same type of transformation could be carried out using butynoates as allene surrogates
DABCO 催化的 3-硝基-2 H-色烯和 2,3-丁二烯酸苄酯之间的 [3 + 3] 环化已被开发为生成 5 H-色烯[3,4- b ] 吡啶衍生物的途径。在最佳反应条件下,以中等至良好的产率(30-76%)获得包含两个烯丙酸酯单元的5 H-色烯[3,4- b ]吡啶。可以使用丁酸作为丙二烯替代物进行相同类型的转化。通过质谱进行的机理研究可以确定参与反应机理的关键中间体。所报道的合成方法代表了一种全新的合成 5 H -chromeno[3,4- b]吡啶核心结构基于丙二烯化学。