Direct Alkynylation of 3<i>H</i>-Imidazo[4,5-<i>b</i>]pyridines Using <i>gem</i>-Dibromoalkenes as Alkynes Source
作者:Jessy Aziz、Tom Baladi、Sandrine Piguel
DOI:10.1021/acs.joc.6b00406
日期:2016.5.20
C2 direct alkynylation of 3H-imidazo[4,5-b]pyridine derivatives is explored for the first time. Stable and readily available 1,1-dibromo-1-alkenes, electrophilic alkyne precursors, are used as coupling partners. The simple reaction conditions include an inexpensive copper catalyst (CuBr·SMe2 or Cu(OAc)2), a phosphine ligand (DPEphos) and a base (LiOtBu) in 1,4-dioxane at 120 °C. This C–H alkynylation
首次探索了3 H-咪唑并[4,5- b ]吡啶衍生物的C2直接炔基化。稳定且易于获得的1,1-二溴-1-烯烃(亲电炔前体)用作偶联伙伴。简单的反应条件包括:廉价的铜催化剂(CuBr·SMe 2或Cu(OAc)2),膦配体(DPEphos)和1,4-二恶烷中的碱(LiO t Bu)在120°C的条件下。该C-H炔基化方法显露是与各种上两个耦合伙伴取代的兼容:杂芳烃和宝石-dibromoalkenes。该协议可以直接合成各种2-炔基-3 H-咪唑并[4,5- b]吡啶,一种在药物设计中有价值的支架。