### 钯催化炔溴和烯烃偶联合成共轭烯炔的研究

1. a 广东海洋大学理学院 湛江 524088;
b 华南理工大学化学与化工学院 广州 510640
• 投稿日期:2012-05-30 发布日期:2012-06-29
• 通讯作者: 江焕峰
• 基金资助:
项目受国家自然科学基金(No. 21172076)、广东省自然科学基金(No. 8451064101000236)资助.

### Palladium-Catalyzed Coupling Reaction of 1-Bromoalkynes with Olefins to Synthesize Enynes

Wen Yanmeia, Jiang Huanfengb

1. a College of Science, Guangdong Ocean University, Zhanjiang 524088, China;
b School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China
• Received:2012-05-30 Published:2012-06-29
• Supported by:
Project supported by the National Natural Science Foundation of China (No. 21172076) and Guangdong Natural Science Foundation (No. 8451064101000236).

1,3-共轭烯炔不仅是有机合成的重要中间体, 许多天然产物和具有生理活性的化合物的核心骨架都含有共轭烯炔单元, 在已有的共轭烯炔的合成方法中钯铜共催化的烯基卤与端炔的Sonogashira 偶联反应占据了统治地位. 炔卤化合物是一种独特有趣的有机分子, 它既能参与类似于端炔的偶联反应, 又具有卤苯的过渡金属氧化加成的性能, 这些特点使炔卤在构建复杂有机分子中起着重要的作用. 我们以Pd(OAc)2为催化剂, K2CO3为碱, 在DMF溶剂中实现了末端烯和炔基溴的交叉偶联反应高区域和立体选择性地合成1,3-共轭烯炔, 考察了催化剂的种类、碱的种类和温度对反应的影响. 研究结果表明: 5 mol% Pd(OAc)2, 2.5 equiv. K2CO3, 在DMF溶剂中, 不需要任何配体和添加剂, 炔基溴与苯乙烯衍生物于80 ℃, 与贫电子烯烃于室温反应2 h可以高产率得到所需产物, 所有化合物的结构用IR, 1H NMR, 13C NMR, MS, 高分辨质谱等方法进行了表征, 该偶联反应合成途径简捷、反应条件温和, 可为共轭烯炔化合物合成提供简便的途径.

1,3-Enynes are very useful synthetic intermediates. Furthermore, enyne moiety is also an important unit often found in many naturally occurring and biologically active compounds. For these reasons, the design and synthesis of such compounds containing an enyne moiety have received considerable attention in organic synthesis and have been extensively studied. Among of these methods, the Sonogashira cross-coupling reaction for the synthesis of enynes between a vinyl halide and a terminal alkyne or organometallic alkyne using Pd-Cu catalyst has become an indispensable and powerful tool for the synthesis of enynes. However, limited attention has been turned to another alternative cross-coupling reaction between a terminal alkene and a haloalkyne which is highly valuable synthon and widely used in synthetic organic chemistry for constructing complex organic compounds due to their versatility. Using Pd(OAc)2 as the catalyst and K2CO3 as the base in DMF, an efficient procedure for the stereoselective synthesis of a series of conjugated enynes by a simple cross-coupling reaction of alkenes and alkynyl bromides has been developed. The effects of catalyst, base and reaction temperature were studied. The result indicated that the reaction proceeds smoothly to give the corresponding products in good to excellent yields using 5 mol% Pd(OAc)2 and 2.5 equiv. K2CO3 in DMF for 2 h at 80 ℃ for arylalkene compounds, room temperature for electron-deficient alkenes. The structure of enyne derivatives was confirmed by IR, 1H NMR, 13C NMR, MS and HRMS. In summary, an efficient and general catalytic system has been developed for the cross-coupling reaction of a wide range of alkenes and bromoalkynes in the absence of any stabilizing ligands or special additives. The process is regio- and stereoselective, and provides good access to a series of functionalized 1,3-enynes in good to excellent yields. Moreover, the reaction is a convenient and simple path for the synthesis of the 1,3-enyne, and tolerates several functional groups on both coupling partners.