An Umpolung Approach to Alkene Carboamination: Palladium Catalyzed 1,2-Amino-Acylation, -Carboxylation, -Arylation, -Vinylation, and -Alkynylation
An Umpolung Approach to Alkene Carboamination: Palladium Catalyzed 1,2-Amino-Acylation, -Carboxylation, -Arylation, -Vinylation, and -Alkynylation
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DOI：
10.1021/jacs.5b03732
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发表时间：
2015-06-10
影响因子：
15
通讯作者：
Bower, John F.
中科院分区：
文献类型：
--
作者：
Faulkner, Adele;Scott, James S.;Bower, John F.
pd催化烯烃1,2-碳胺化的传统方法依赖于亲核氮基组分和内部c基或外部氧化剂的组合。在这项研究中，我们概述了一种umpolung方法，该方法由亲电n基组分的氧化引发，并采用“标准”有机金属亲核试剂引入新的碳基片段。具体来说，在o-五氟苯甲酰肟酯的N-O键上氧化加成Pd(0)-催化剂生成亚胺-Pd（II）中间体，这些中间体与空间上不同的烯烃进行5-外环化。在羰基化或非羰基化条件下，生成的烷基钯（II）中间体被有机金属亲核试剂或醇截获，生成1,2-碳胺化产物。这种方法首次提供了实现烯烃1,2-氨基酰化、-羧基化、-芳基化、-乙烯基化和-炔基化的统一策略。在羰基化过程中，五氟苯甲酸酯离去基的有序原脱羧是反应效率的基础。这一过程可能是相关Narasaka-Heck环化反应的一个关键特征，并解释了o -五氟苯甲酰肟酯在这种类型的aza-Heck反应中的功效。
Conventional approaches to Pd-catalyzed alkene 1,2-carboamination rely upon the combination of a nucleophilic nitrogen-based component and an internal C-based or external oxidant. In this study, we outline an umpolung approach, which is triggered by oxidative initiation at an electrophilic N-based component and employs "standard" organometallic nucleophiles to introduce the new carbon-based fragment. Specifically, oxidative addition of a Pd(0)-catalyst into the N-O bond of O-pentafluorobenzoyl oxime esters generates imino-Pd(II) intermediates, which undergo 5-exo cyclization with sterically diverse alkenes. The resultant alkyl-Pd(II) intermediates are intercepted by organometallic nucleophiles or alcohols, under carbonylative or noncarbonylative conditions, to provide 1,2-carboamination products. This approach provides, for the first time, a unified strategy for achieving alkene 1,2-amino-acylation, -carboxylation, -arylation, -vinylation, and -alkynylation. For carbonylative processes, orchestrated protodecarboxylation of the pentafluorobenzoate leaving group underpins reaction efficiency. This process is likely a key feature in related Narasaka-Heck cyclizations and accounts for the efficacy of O-pentafluorobenzoyl oxime esters in aza-Heck reactions of this type.