Hydroacylation of activated ketones catalyzed by N-heterocyclic carbenes
Hydroacylation of activated ketones catalyzed by N-heterocyclic carbenes
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DOI：
10.1021/ja060833a
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发表时间：
2006-04-12
影响因子：
15
通讯作者：
Scheidt, KA
中科院分区：
文献类型：
--
作者：
Chan, A;Scheidt, KA
由三唑盐衍生的N-杂环卡宾是活化酮氢酰化反应的有效催化剂，其摩尔分数在10-15%之间。还原当量是通过亲核卡宾物种和芳香醛的相互作用生成的。随后的醇产品可以与所产生的在NHC和醛之间原位形成的酰基杂氮唑中间体发生酰化反应。这种史无前例的多重成键反应可以容纳芳香醛作为氢化物来源和各种电子缺陷酮。初步的机理证据表明，还原和酰化步骤是连续的操作。这种有机催化反应的分子内变体以良好的产率提供了苯并呋喃酮。
N-heterocyclic carbenes derived from triazolium salts are effective catalysts between 10 and 15 mol % for the hydroacylation of activated ketones. The reducing equivalent is generated via the interaction of a nucleophilic carbene species and an aromatic aldehyde. The subsequent alcohol product can undergo an acylation event with the resulting acyl heteroazolium intermediate formed in situ between the NHC and the aldehyde. This unprecedented multiple bond-forming reaction can accommodate aromatic aldehydes as the hydride source and various electron-deficient ketones. Preliminary mechanistic evidence indicates that the reduction and acylation steps are sequential operations. The intramolecular variant of this organocatalytic reaction affords benzofuranones in good yield.