Silver-catalyzed C(sp)-H and C(sp)-Si bond transformations and related processes.
Silver-catalyzed C(sp)-H and C(sp)-Si bond transformations and related processes.
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DOI：
10.1021/cr078359u
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发表时间：
2008-07
期刊：
影响因子：
62.1
通讯作者：
Yoshihiko Yamamoto
中科院分区：
文献类型：
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作者：
Yoshihiko Yamamoto
炔是用途极为广泛的不饱和烃，1广泛存在于功能材料、2超分子、3和天然产物中。4此外，它们也是有用的合成中间体，可以通过它们的CC三键之间的加成反应从其获得各种饱和和不饱和化合物。特别是，过渡金属催化的炔类转化的最新进展为复杂分子结构提供了快速而简洁的途径。6因此，发展一种新的制备取代炔的方法有望大大扩展基于它们的转化的合成方法的实用性。Csp 3取代的炔通常通过末端炔前体的去质子化和随后所得金属乙炔化物与亲电试剂如烷基卤化物和羰基化合物的反应来合成。7由于炔属质子的酸度高于烷烃和烯烃的酸度（乙炔、乙烯和乙烷相对于水的pKa值分别为25、44和50），8末端炔的去质子化通常使用烷基锂或格氏试剂在惰性气体气氛下在干燥的非质子溶剂中进行，或者使用碱金属酰胺在液氨中进行。由于它们对空气和湿气的敏感性，原位形成的乙炔化物直接用于进一步的反应而无需分离。相反，银炔化物可以很容易地从末端炔与氨性银盐制备，并且它们可以作为沉淀物分离。[9]然而，分离的银乙炔化物已经用于相当有限数量的合成有用的CC键形成。9d这些反应涉及对酰卤、9a、10芳基重氮盐、11亚氨基氯化物、12呋喃核糖基卤化物、13和烷基卤化物14的取代反应，或对亚胺盐15和吡啶盐16、醛17和CO2的加成反应。18.虽然金属乙炔化物的化学计量使用已经得到很好的确立，但从原子和步骤经济的角度来看，一种能够催化生成和同时转化金属乙炔化物的工艺是理想的。19，20此外，这种催化方法具有显著的优点，根据该优点，可以避免直接处理潜在爆炸性的乙炔银。本文综述了银催化的过程，其中炔属Csp-H以及Csp-Si键的转化在银介体的影响下发生。为了显示银催化的Csp-H和Csp-Si键官能化的合成实用性，还概述了所得产物的相关转化。
Alkynes are extremely versatile unsaturated hydrocarbons, 1 which are ubiquitously found in functional materials, 2 supramolecules, 3 and natural products. 4 Further, they are also useful synthetic intermediates from which a wide variety of saturated and unsaturated compounds can be obtained via addition reactions across their CC triple bonds. 5 In particular, recent advances in the transition-metal-catalyzed transformations of alkynes have provided rapid and concise access to complex molecular architectures. 6 Therefore, the development of a new preparative method of substituted alkynes promises to greatly expand the utility of the synthetic methodologies based on their transformations. Csp3-substituted alkynes have conventionally been synthesized through the deprotonation of terminal alkyne precursors and subsequent reactions of the resultant metal acetylides with electrophiles such as alkyl halides and carbonyl compounds. 7 Since the acidity of acetylenic protons is higher than those of alkanes and alkenes (pKa values of acetylene, ethylene, and ethane relative to water are 25, 44, and 50, respectively), 8 the deprotonation of terminal alkynes has been routinely performed using alkyllithiums or Grignard reagents in dry aprotic solvents under an inert gas atmosphere or alternatively with alkali metal amides in liquid ammonia. Because of their air and moisture sensitivities, acetylides formed in situ are directly used for further reactions without isolation. In contrast, silver acetylides can be readily prepared from terminal alkynes with ammoniacal silver salts, and they are isolable as precipitates. 9 The isolated silver acetylides, however, have been employed in a rather limited number of synthetically useful CC bond formations. 9d These involve the substitution reactions on acyl halides, 9a, 10 aryldiazonium salts, 11 iminochlorides, 12 ribofuranosyl halides, 13 and alkyl halides14 or additions to iminium15 and pyridinium16 salts, aldehydes, 17 and CO2. 18 While the stoichiometric use of metal acetylides has been well established, a process that enables their catalytic generation and simultaneous transformation is ideal in terms of atom and step economies. 19, 20 In addition, such a catalytic process has a significant merit according to which the direct handling of potentially explosive silver acetylides can be avoided. 9a This review surveys the silver-catalyzed processes in which acetylenic Csp-H as well as Csp-Si bond transformations occur under the influence of silver mediators. To show the synthetic utility of silver-catalyzed Csp-H and Csp-Si bond functionalizations, relevant transformations of the resulting products are also outlined.