Metal-free catalytic hydrogenation
Metal-free catalytic hydrogenation
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DOI：
10.1002/anie.200702908
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Stephan, Douglas W.
中科院分区：
文献类型：
--
作者：
Chase, Preston A.;Welch, Gregory C.;Stephan, Douglas W.
氢化是将氢加成到不饱和有机化合物上。这种反应用于生产世界各地的无数化学产品，从大规模操作，包括原油的升级和大宗商品材料的生产，到食品，农业和制药工业中使用的各种精细化学品的合成。[1]氢加成到不饱和前体的过程由均相或非均相过渡金属基催化剂介导。[1]Blaser等人[2]他指出，“氢气是最清洁的还原剂，氢化可以说是实验室和生产规模上合成有机化学中最重要的催化方法”。从历史上看，加氢反应始于Sabatier在1897年发现微量的镍可以介导烯烃的催化加氢反应，并最终与Grignard分享了1912年的诺贝尔奖。在20世纪60年代，有机金属化学的出现产生了用于各种底物的均相过渡金属基氢化催化剂。这些催化剂的操作取决于氢的氧化加成这一关键步骤。[3]最近，已经发现了在金属中心实现氢的异裂的过渡金属系统。在这些情况下，金属氢化物与酰胺基配体的同时质子化形成。[4，5]用于氢化反应的非过渡金属催化剂几乎是未知的。KOtBu已被证明在200 ℃和大于100巴H2的强制条件下作为催化剂实现H2加成到二苯甲酮。[6]已经开发了用于烯酮和亚胺的氢化的有机催化剂;然而，这样的系统不直接使用H2，而是使用替代物如Hantzsch酯作为氢的化学计量来源。[7-11]非金属加氢催化剂的发展取决于与H2清洁反应的体系的发现，但很少有人知道。Power和同事报道了Ge 2-炔类似物的氢化，得到Ge 2和主要锗烷产物的混合物。[12]最近，我们引入了“阻挫刘易斯对”的概念，即在空间上不能形成简单刘易斯的大体积刘易斯酸和碱
Hydrogenation is the addition of hydrogen to unsaturated organic compounds. Such reactions are used for the production of a myriad of chemical products worldwide, from largescale operations including the upgrading of crude oil and the production of bulk commodity materials to the synthesis of a variety of fine chemicals used in the food, agricultural, and pharmaceutical industries.[1] The process of hydrogen addition to unsaturated precursors is mediated by either homogeneous or heterogeneous transition-metal-based catalysts.[1] Blaser et al.[2] place the importance of this chemistry in context, stating that “hydrogen is the cleanest reducing agent and hydrogenation is arguably the most important catalytic method in synthetic organic chemistry both on the laboratory and the production scale”. Historically, hydrogenation began with Sabatier s 1897 discovery that traces of nickel could mediate the catalytic hydrogenation of olefins and culminated in a share of the 1912 Nobel Prize with Grignard. In the 1960s, the advent of organometallic chemistry gave rise to homogeneous transition-metal-based hydrogenation catalysts for a variety of substrates. The operation of these catalysts hinges on the key step of oxidative addition of hydrogen.[3] More recently, transition-metal systems that effect heterolytic cleavage of hydrogen at a metal center have been uncovered. In these cases, a metal hydride is formed with concurrent protonation of an amido ligand.[4, 5]Non-transition-metal catalysts for hydrogenation reactions are all but unknown. KOtBu has been shown to act as a catalyst effecting the addition of H2 to benzophenone under forcing conditions of 2008C and greater than 100 bar H2.[6] Organocatalysts have been developed for hydrogenations of enones and imines; however, such systems do not employ H2 directly but rather a surrogate such as a Hantzsch ester as the stoichiometric source of hydrogen.[7–11] The development of nonmetal hydrogenation catalysts hinges on the discovery of systems that react cleanly with H2, but few are known. Power and co-workers reported the hydrogenation of Ge2–alkyne analogues to give a mixture of Ge2 and primary germane products.[12] Recently we have introduced the concept of “frustrated Lewis pairs”, bulky Lewis acids and bases which are sterically precluded from forming simple Lewis