NHC-Catalyzed Michael Addition to α,β-Unsaturated Aldehydes by Redox Activation
NHC-Catalyzed Michael Addition to α,β-Unsaturated Aldehydes by Redox Activation
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DOI：
10.1002/anie.201004593
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发表时间：
2010-01-01
影响因子：
16.6
通讯作者：
Studer, Armido
中科院分区：
文献类型：
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作者：
De Sarkar, Suman;Studer, Armido
C2C键的形成无疑属于有机化学中最重要的转化，迈克尔反应就是其中的重要例子。[1]迈克尔受体的活化主要遵循两种策略来进行共轭加成反应：a）通过使用刘易斯[2]或布朗斯台德[3]酸活化和B）通过亚胺离子产生活化。[4]Bode和Glorius [5]已经独立地表明，α，β不饱和醛1与N-杂环卡宾（NHC）2反应生成A型的非极性[6]中间体，然后该中间体可以作为β位的高烯醇化物与各种亲电试剂反应生成产物B（方案1）。[7]We最近表明，Breslow中间体A可以容易地用温和的有机氧化剂氧化成C型酰基唑鎓离子，其与各种O亲核试剂进行有效的O酰化，得到相应的酯。[8-10]基于这些结果，我们决定使用氧化生成的中间体C作为Michael受体，使用软C亲核试剂进行1，4-加成反应。有
The formation of CÀC bonds undoubtedly belongs to the most important transformations in organic chemistry, and Michael reactions are important examples thereof.[1] Two strategies have mainly been followed for the activation of Michael acceptors to conduct conjugate addition reactions: a) activation by using Lewis [2] or Brønsted [3] acids and b) activation by iminium ion generation.[4] It has been shown independently by Bode and Glorius [5] that α, βunsaturated aldehydes 1 react with N-heterocyclic carbenes (NHCs) 2 to umpoled [6] intermediates of type A, which can then react as homoenolates at the β position with various electrophiles to give product B (Scheme 1).[7]We recently showed that Breslow intermediates A can be readily oxidized with mild organic oxidants to acylazolium ions of type C, which undergo efficient Oacylation with various O nucleophiles to give the corresponding esters.[8–10] Based on these results we decided to use oxidatively generated intermediates C as Michael acceptors to conduct 1, 4-addition reactions using soft Cnucleophiles. There is