Synthesis of Polysubstituted Cyclopentene and Cyclopenta[b]carbazole Analogues from Unsymmetrical 4‑Arylidene-3,6-diarylhex-2-en-5-ynal and Indole Derivatives via an Iodine Mediated Electrocyclization Reaction

An efficient method for the synthesis of polysubstituted cyclopentene and cyclopenta­[b]­carbazole derivatives through the iodine-promoted electrocyclization of substituted indoles and 4-arylidene-3,6-diarylhex-2-en-5-ynal derivatives is reported. Polysubstituted cyclopentene derivatives were produced through 4π electrocyclization reactions with indole, 7-methylindole, and 5-bromoindole as coupling partners, whereas cyclopenta­[b]­carbazole derivatives were produced via 6π electrocyclization in the case of methoxy (−OMe)-substituted indoles. The methods reported herein diastereo- and regioselectively proceed under straightforward and mild conditions.本文报道了一种高效合成方法，可通过碘促进的取代吲哚与4-亚芳基-3,6-二芳基己-2-烯-5-炔醛衍生物的电环化反应，制备多取代环戊烯及环戊并[b]咔唑（cyclopenta[b]carbazole）衍生物。当以吲哚、7-甲基吲哚及5-溴吲哚作为偶联底物时，反应经由4π电环化过程生成多取代环戊烯衍生物；而当使用甲氧基（-OMe）取代的吲哚时，则通过6π电环化路径得到环戊并[b]咔唑衍生物。本研究所报道的方法具备优异的非对映选择性与区域选择性，且反应条件简便温和。