催化学报

催化学报 ›› 2016, Vol. 37 ›› Issue (6): 979-986.DOI: 10.1016/S1872-2067(15)61084-1

• 论文 • 上一篇    

Lewis碱协助的Lewis酸催化醇脱水合成烯烃及二氢吡喃开环合成2-肉桂基取代1,3-二羰基化合物

刘昌会a, 潘彬a, 顾彦龙a,b   

  1. a 华中科技大学能量转化与存储材料化学教育部重点实验室, 材料化学与服务失效湖北省重点实验室, 湖北武汉 430074;
    b 中国科学院兰州化学物理研究所羰基合成与选择性氧化国家重点实验室, 甘肃兰州 730000
  • 收稿日期:2016-02-05 修回日期:2016-03-15 出版日期:2016-05-30 发布日期:2016-05-30
  • 通讯作者: Yanlong Gu
  • 基金资助:

    国家自然科学基金(21173089, 21373093); 中央高校基本科研业务费专项资金(2014ZZGH019); 湖北省催化化学协同创新中心.

Lewis base-assisted Lewis acid-catalyzed selective alkene formation via alcohol dehydration and synthesis of 2-cinnamyl-1,3-dicarbonyl compounds from 2-aryl-3,4-dihydropyrans

Changhui Liua, Bin Pana, Yanlong Gua,b   

  1. a Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Hubei Key Laboratory of Material Chemistry and Service Failure, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China;
    b State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China
  • Received:2016-02-05 Revised:2016-03-15 Online:2016-05-30 Published:2016-05-30
  • Contact: Yanlong Gu
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21173089 and 21373093), the Fundamental Research Funds for the Central Universities of China (2014ZZGH019), and the Cooperative Innovation Center of Hubei Province.

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摘要：

醇脱水是合成烯烃的重要方法之一. 全球每年约有15%的苯乙烯是通过1-苯乙醇在酸性条件下脱水反应生产. 虽然人们对该反应进行了较为深入的研究, 但是当使用活性较高的1-苯乙醇衍生物为底物时, 由于得到的取代苯乙烯产物具有较高的反应性, 在脱水过程中会发生聚合而导致反应选择性降低, 因此有必要探索适宜在高活性1-苯基乙醇脱水反应中应用的催化剂体系.
本文借助酸碱协同催化方法考察了1-(4-甲氧基苯基)乙醇制备 4-甲氧基苯乙烯的反应. 发现三苯基磷与 AlCl3 构建的 Lewis 碱/Lewis 酸协同催化体系在硝基甲烷中可以接近定量的收率得到 4-甲氧基苯乙烯. Lewis碱/Lewis酸协同催化体系有效避免了4-甲氧基苯乙烯的二聚现象. 底物拓展研究显示该方法具有很好的底物普适性, 对多种取代苯乙烯的收率均超过 80%. 机理研究表明, 1-(4-甲氧基苯基)乙醇在酸作用下先生成碳正离子, 三苯基磷作为偶极性的电子给体不但能在一定程度上稳定该苄基碳正离子, 而且抑制了其与4-甲氧基苯乙烯之间的亲电反应, 进而最大化了脱质子生成4-甲氧基苯乙烯的选择性.
将Lewis 碱协助的 Lewis 酸催化提高反应选择性策略用于2-苯基-3,4-二氢吡喃衍生物合成2-肉桂基-1,3-二羰基化合物的开环反应. 该类取代二氢吡喃在酸催化剂作用下也可生成苄基碳正离子, 但是该中间体易受分子间和分子内亲电反应影响, 反应选择性不高. 而当使用单质碘/三苯基磷协同催化体系时, 2-苯基-3,4-二氢吡喃衍生物能高选择性地实现开环反应, 得到反式 2-肉桂基-1,3-二羰基化合物. 该类1,3-二羰基化合物具有丰富的反应性, 是一类重要的合成子.

关键词: 协同催化, 酸碱催化, 醇脱水, 2-肉桂基-1,3-二羰基化合物, 均相催化剂

Abstract:

Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often plagued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4- dihydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.

Key words: Synergistic catalysis, Acid-base catalysis, Dehydration of alcohol, 2-Cinnamyl-1,3-dicarbonyl compound, Homogeneous catalysis