关键词: 苯炔, 四炔模块, 咔唑, 杂环化合物, 咔唑类衍生物

Benzyne is one of very important reactive intermediates in organic synthesis, and has been comprehensively utilized as a building block in organic synthesis. However, traditional synthetic methods need to use harsh reaction condition, which has limited its practical application. With the emergence of moderate preparation method, benzyne has attracted considerable attentions from synthetic chemists. Latest results indicate that benzyne can be effectively generated by using some special intermediates containing three or four acetylene motifs, which called the hexadehydro-Diels-Alder (HDDA) reaction. This thermal cycloisomerization of a triyne precursor constitutes a reagent and byproduct free method for making benzyne intermediates of considerable structural complexity. On the other hand, carbazole and its derivatives is one very important type of nitrogen-containing aromatic heterocyclic compounds. They are used as pharmaceuticals, agrochemicals, dyes, pigments, light-emitting photosensizer, charge/hole transport material and photovoltaic and display devices, etc. Various functional groups can be easily introduced into carbazole ring through structural modification. Develop new synthetic methodology for the synthesis of carbazole and its derivatives is very important. In this paper, we took advantage of the hexadehydro Diels-Alder reaction of bis-1,3-diynes to generate arynes and used them for an intramolecular nucleophile addition reaction to generate various carbazole derivatives. A series of four acetylene-containing compounds were synthesized through the corresponding Cadiot-Chodkiewicz coupling reaction in good yields. The corresponding carbazole derivatives were received in good yields after heating benzyne precursors of four acetylene modules in toluene at 90 ℃ for 5 h. These reaction exhibited very high efficiency as well as wide substrate scope. In addition, we found that the carbazole ring and indole ring were formed simultaneously in one step with using AgNO₃ as catalyst. The possible mechanism of corresponding N—H insertion reaction involves AgNO₃ as a catalyst was proposed. This strategy provides a new way for the synthesis of heterocyclic compounds.

Key words: benzyne, four acetylene module, carbazole, heterocyclic compound, carbazole derivative