Structure-activity relationships for group 4 biaryl amidate complexes in catalytic hydroamination/cyclization of aminoalkenes
Structure-activity relationships for group 4 biaryl amidate complexes in catalytic hydroamination/cyclization of aminoalkenes
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DOI：
10.1021/om061087l
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发表时间：
2007-03-26
期刊：
影响因子：
2.8
通讯作者：
Scott, Peter
中科院分区：
文献类型：
--
作者：
Gott, Andrew L.;Clarke, Adam J.;Scott, Peter
以（R，S）-2，2 '-二氨基-6，6'-二甲基联苯为原料，经酰氯处理，合成了双酰胺前配体。与第4族金属的均配烷基直接反应干净地产生酰胺化物配合物。单晶X射线衍射表明，这些配合物在钛的情况下是单体，在锆的情况下是二聚体。所形成的络合物在与标准硼酸盐/硼烷活化剂反应时不产生明确的阳离子，并且尽管观察到一些氢化胺化催化，但其不是以有用的速率。Zr（NMe 2）（4）与前配体H2 L1 -4的原位处理产生了根据酰胺取代基的空间体积而变化的核性的配合物，但与金属烷基系列相反，单核物种是可接近的;发现均三甲苯基衍生物[（S）-（LZr）-Zr-4（NMe 2）（2）]是用于1-氨基-2-甲基苯的氢胺化/环化的高对映选择性催化剂，2-二甲基异丙基-4-烯，对映体过量为91%。
Synthesis of bis(carboxamide) proligands derived from (R,S)-2,2'-diamino-6,6'dimethylbiphenyl was readily achieved by treatment of the amine with acid chlorides. Direct reaction with homoleptic alkyls of the group 4 metals cleanly yielded amidate complexes. These complexes were shown by single-crystal X-ray diffraction to be monomeric in the case of titanium and dimeric in the case of zirconium. The complexes formed do not yield well-defined cations upon reaction with standard borate/borane activators, and although some hydroamination catalysis was observed, it was not at a rate that is useful. In-situ treatment of Zr(NMe2)(4) with the proligands H2L1-4 yielded complexes of varying nuclearity depending on the steric bulk of the amide substituents, but in contrast to the metal alkyl series, mononuclear species are accessible; the mesityl derivative [(S)-(LZr)-Zr-4(NMe2)(2)] was found to be a highly enantioselective catalyst for the hydroamination/cyclization of 1-amino-2,2-dimethylpent-4-ene, with an enantiomeric excess of 91%.