Reactions of 2-Substituted Pyridines with Titanocenes and Zirconocenes: Coupling versus Dearomatisation.
Reactions of 2-Substituted Pyridines with Titanocenes and Zirconocenes: Coupling versus Dearomatisation.
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DOI：
10.1002/chem.201504411
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
F. Reiß;Kai Altenburger;Lisanne Becker;Kathleen Schubert;H. Jiao;A. Spannenberg;D. Hollmann;P. Arndt;U. Rosenthal
中科院分区：
文献类型：
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作者：
F. Reiß;Kai Altenburger;Lisanne Becker;Kathleen Schubert;H. Jiao;A. Spannenberg;D. Hollmann;P. Arndt;U. Rosenthal
研究了第4族茂金属源与2-取代吡啶的反应，以评估它们在无辜脱芳和还原脱芳之间的配位类型，并探讨偶联的可能性。观察到对双金属配体（Cp，Cp*），金属（Ti，Zr）和底物（2-苯基-，2-乙酰基-和2-亚氨基吡啶）的依赖性。虽然2-苯基吡啶几乎没有反应性，但2-乙酰基吡啶与Cp-取代的配合物剧烈反应，并选择性地与它们的Cp* 类似物反应。与2-亚氨基吡啶，在所有情况下，观察到选择性反应。在分离的[Cp 2 Ti]、[Cp 2 Zr]和[Cp*2 Zr]化合物中，底物通过其吡啶基环和不饱和侧链配位。随后，吡啶脱芳构化，这在[Cp*2 Zr]化合物中最明显。使用[Cp*2 Ti]导致意外的顺磁性络合物[Cp*2 TiIII（N，O-acpy）]和[Cp*2 TiIII（N，N '-impy）]。这突出了吡啶基底物的非无辜特性。
Reactions of group 4 metallocene sources with 2-substituted pyridines were investigated to evaluate their coordination type between innocent and reductive dearomatisation as well as to probe the possibility for couplings. A dependence on the cyclopentadienyl ligands (Cp, Cp*), the metals (Ti, Zr), and the substrates (2-phenyl-, 2-acetyl-, and 2-iminopyridine) was observed. While 2-phenylpyridine is barely reactive, 2-acetylpyridine reacts vigorously with the Cp-substituted complexes and selectively with their Cp* analogues. With 2-iminopyridine, in all cases selective reactions were observed. In the isolated [Cp2 Ti], [Cp2 Zr], and [Cp*2 Zr] compounds the substrate coordinates by its pyridyl ring and the unsaturated side-chain. Subsequently, the pyridine was dearomatised, which is most pronounced in the [Cp*2 Zr] compounds. Using [Cp*2 Ti] leads to the unexpected paramagnetic complexes [Cp*2 TiIII (N,O-acpy)] and [Cp*2 TiIII (N,N'-impy)]. This highlights the non-innocent character of the pyridyl substrates.