Amine oxidative N-dealkylation via cupric hydroperoxide Cu-OOH homolytic cleavage followed by site-specific fenton chemistry.
Amine oxidative N-dealkylation via cupric hydroperoxide Cu-OOH homolytic cleavage followed by site-specific fenton chemistry.
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DOI：
10.1021/ja508371q
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发表时间：
2015-03-04
影响因子：
15
通讯作者：
Karlin, Kenneth D.
中科院分区：
文献类型：
--
作者：
Kim, Sunghee;Ginsbach, Jake W.;Lee, Jung Yoon;Peterson, Ryan L.;Liu, Jeffrey J.;Siegler, Maxime A.;Sarjeant, Amy A.;Solomon, Edward I.;Karlin, Kenneth D.
铜(II)-氢过氧化物是燃料电池和（生物）化学氧化等过程中的重要中间体，所有这些过程都涉及分子氧的逐步还原。我们之前报道了一种CuII-OOH物质，它可以对附着在三足四齿配体的吡啶基供体6位上的二苄胺基进行氧化n -脱烷基。为了深入了解这一过程的机理，采用不同对取代二苄基对（- h,- h,- cl; - h，- ome和- cl，- ome）或部分或完全氘化二苄基N-(CH2Ph)2的配体底物来测定反应动力学和产物。合成了一系列配体-双高氯酸铜（II）配合物，对其进行了表征，并测定了-H， -OMe类似物的x射线结构。H2O2/碱在-90℃丙酮中加成生成相应的亚稳CuII-OOH。这些转化（t1/2 ~ 53 s）为氧化n脱烷基产物，产生对取代苯甲醛。基于实验观察和支持的DFT计算，可以排除涉及二苯胺h原子抽离或CuII-OOH实体的电子转移氧化的反应机制。结果表明，化学反应首先是CuII - (OOH)的限速Cu-O均溶裂解，然后是特定位点的铜Fenton化学反应。作为铜和铁氧化（生物）化学的一个广泛关注的过程，进行了详细的计算分析，表明CuIOOH物种经历O-O均裂裂解产生羟基自由基和CuIIOH，而不是异裂裂解产生水和CuII-O•−。
Copper(II)-hydroperoxide species are significant intermediates in processes such as fuel cells and (bio)chemical oxidations, all involving stepwise reduction of molecular oxygen. We previously reported a CuII-OOH species that performs oxidative N-dealkylation on a dibenzylamino group that is appended to the 6-position of a pyridyl donor of a tripodal tetradentate ligand. To obtain insights into the mechanism of this process, reaction kinetics and products were determined employing ligand substrates with various para- substituent dibenzyl pairs (-H,-H; -H,-Cl; -H,-OMe and -Cl,-OMe), or with partially or fully deuterated dibenzyl N-(CH2Ph)2 moieties. A series of ligand-copper(II) bis-perchlorate complexes were synthesized, characterized, and the X-ray structures of the -H, -OMe analog was were determined. The corresponding metastable CuII-OOH species were generated by addition of H2O2/base in acetone at –90 °C. These convert (t1/2 ~ 53 s) to oxidatively N-dealkylated products, producing para-substituted benzaldehydes. Based on the experimental observations and supporting DFT calculations, a reaction mechanism involving dibenzylamine H-atom abstraction or electron-transfer oxidation by the CuII-OOH entity could be ruled out. It is concluded that the chemistry proceeds by rate limiting Cu–O homolytic cleavage of the CuII–(OOH) species, followed by site-specific copper Fenton chemistry. As a process of broad interest in copper as well as iron oxidative (bio)chemistries, a detailed computational analysis was performed, indicating that a CuIOOH species undergoes O–O homolytic cleavage to yield a hydroxyl radical and CuIIOH rather than heterolytic cleavage to yield water and a CuII-O•−.
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影响因子：
4.8
作者：
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通讯作者：
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