Group-Transfer Reactions of a Cationic Iridium Alkoxycarbene Generated by Ether Dehydrogenation
Group-Transfer Reactions of a Cationic Iridium Alkoxycarbene Generated by Ether Dehydrogenation
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DOI：
10.1021/acs.inorgchem.0c00609
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发表时间：
2020-05-18
影响因子：
4.6
通讯作者：
Schley, Nathan D.
中科院分区：
文献类型：
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作者：
Chapp, Scott M.;Schley, Nathan D.
尽管对金属卡宾络合物有广泛的兴趣，但仍然存在通过由α，α-脱氢产生的烷氧基卡宾中间体进行的醚的催化转化的几个实例。我们证明了中性和阳离子烷氧基卡宾衍生物都可以在PNP（iPr）（4）钳形负载的铱配合物（PNP（iPr）（4）= 2，6-双（（二异丙基膦基）甲基）吡啶）上通过醚脱氢获得。阳离子和中性烷氧基卡宾配合物都经历与叠氮化物的基团转移亚胺化，其中阳离子衍生物充当环戊基醚亚胺化的更有效的催化剂。机制研究支持铱（I）二氮复合物在黑暗中的静止状态和光促进N-2解离的作用。亚硝酸异戊酯和苯基乙基乙烯酮也被发现从事与阳离子烷氧基卡宾配合物在正式的醇盐和O原子转移反应，分别。在前一种情况下，获得了可分离的二烷氧基烷基铱络合物，其仅代表过渡金属的结构表征的二烷氧基烷基络合物的第二实例。
Despite broad interest in metal carbene complexes, there remain few examples of catalytic transformations of ethers that proceed via alkoxycarbene intermediates generated by alpha,alpha-dehydrogenation. We demonstrate that both neutral and cationic alkoxycarbene derivatives are accessible via ether dehydrogenation at a PNP(iPr)(4) pincer-supported iridium complex (PNP(iPr)(4) = 2,6-bis((diisopropylphosphino)methyl)pyridine). Both cationic and neutral alkoxycarbene complexes undergo group transfer imination with azides, with the cationic derivative serving as a more efficient catalyst for cyclopentyl ether imination. Mechanistic studies support an iridium(I)dinitrogen complex as the resting state in the dark and a role for light-promoted N-2 dissociation. Isoamyl nitrite and phenyl ethyl ketene are also found to engage with the cationic alkoxycarbene complex in formal alkoxide and O atom transfer reactions, respectively. In the former case an isolable dialkoxyalkyliridium complex is obtained, representing only the second example of a structurally characterized dialkoxyalkyl complex of a transition metal.