Reduction of Cp2ZrCl2 with Mischmetall: A New Method for Generating an Efficient “Cp2Zr” Equivalent
摘要:
A "Cp2Zr" equivalent is generated under mild conditions (THF, room temperature) by reducing Cp2ZrCl2 with cheap and readily available mischmetall (an alloy of Ce, La, Nd, and Pr). Coupling reactions, including those of terminal alkynes, can efficiently be achieved by using this reagent.
The Transient Titanocene(II): Direct Synthesis from Solvated Titanium(II) Chloride and Cyclopentadienylsodium and Ensuing Interception with Diphenylacetylene as 1,1‐Bis(cyclopentadienyl)‐2,3,4,5‐tetraphenyltitanacyclopentadiene
作者:John J. Eisch、Adetenu A. Adeosun、John M. Birmingham
DOI:10.1002/ejic.200600766
日期:2007.1
LiCl and NaCl from the reaction mixture, then no trace of the titanacyclopentadiene derivative was found upon hydrolytic workup. Instead, a significant portion of the acetylene was found to have undergone hydrotitanation. This finding is clear evidence that the titanocene(II) had undergone a precedented rearrangement to a known dimer having the structure of a titanocene(III) hydride with a fulvalene
首次通过威尔金森茂金属方法直接合成了不稳定的二茂钛 (II),即四氢呋喃可溶形式的氯化钛 (II) 与两当量的环戊二烯基钠在 0°–25 °C 的四氢呋喃溶液中的相互作用. 由于由此获得的二茂钛 (II) 的短暂存在,它只能被两当量的二苯乙炔以高产率化学捕获为 1,1-双(环戊二烯基)-2,3,4,5-四苯基钛环戊二烯,如果在 25 °C 下加入乙炔,不去除副产物 LiCl 和 NaCl。如果延迟加入乙炔,以便从反应混合物中滤出 LiCl 和 NaCl,则在水解后处理时不会发现痕量的钛环戊二烯衍生物。反而,发现很大一部分乙炔已经过氢化钛化。这一发现是明确的证据,表明二茂钛 (II) 已经经历了先例重排,成为已知的二聚体,该二聚体具有二茂钛 (III) 氢化物的结构,在钛中心之间具有富瓦烯桥。我们建议未过滤的反应混合物中存在的 LiCl 和 NaCl 与二茂钛 (II) 形成二氯络合物,从而阻止其二聚重排为二茂钛
Synthesis and transformations of metallacycles 35. Joint cycloalumination of cyclic 1,2-dienes with disubstituted acetylenes and terminal allenes under the action of EtAlCl2 catalyzed by Ti and Zr complexes
作者:V. A. D’yakonov、R. K. Timerkhanov、T. V. Tyumkina、U. M. Dzhemilev
DOI:10.1007/s11172-009-0344-4
日期:2009.12
Catalytic intermolecular cycloalumination of cyclic 1,2-dienes with terminal allenes or disubstitutedacetylenes mediated by EtAlCl2 in the presence of complexes based on transition metals was accomplished. The yield of unsaturated bicyclic aluminacarbocycles was up to 85%.