Jónsson Helgi Freyr, Orthaber Andreas, Fiksdahl Anne
Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
Department of Organic Chemistry - Ångström Laboratory, Uppsala University, Lägerhyddsvägen 1, 751 20, Uppsala, Sweden.
Dalton Trans. 2021 Apr 21;50(15):5128-5138. doi: 10.1039/d1dt00387a.
Five pairs of novel chiral alcohol functionalised gold(i) and gold(iii) NHC complexes derived from chiral amino alcohols, were synthesized and characterised (NMR, IR, HRMS). Single crystal X-ray diffraction data of gold(i) and gold(iii) complexes are reported and discussed. The chiral imidazolium preligands were readily synthesized via the oxalamides, subsequent reduction and final orthoformate condensation. An improved method was used for generation of gold(i) NHC complexes (up to 92%) and further oxidation afforded the corresponding gold(iii) NHC complexes (up to 99%). All the Au(i) and Au(iii) NHC complexes proved far more catalytically active in a 1,6-enyne alkoxycyclization test reaction than our previously tested N,N- and P,N-ligated Au(iii) complexes. Comparative gold(i) and gold(iii) catalytic studies demonstrated different catalytic ability, depending on the NHC ligand flexibility and bulkiness. Excellent yields (92-99%) of target alkoxycyclization product were obtained with both gold(i) and gold(iii) complexes with the bulky N1-Mes-N2-ethanol based NHC ligand.
合成并表征了（通过核磁共振、红外光谱、高分辨质谱）五对源自手性氨基醇的新型手性醇官能化金（Ⅰ）和金（Ⅲ）氮杂环卡宾配合物。报道并讨论了金（Ⅰ）和金（Ⅲ）配合物的单晶X射线衍射数据。手性咪唑鎓前体配体可通过草酰胺、后续还原以及最后的原甲酸酯缩合轻松合成。采用一种改进方法生成金（Ⅰ）氮杂环卡宾配合物（产率高达92%），进一步氧化得到相应的金（Ⅲ）氮杂环卡宾配合物（产率高达99%）。在1,6-烯炔烷氧基环化测试反应中，所有金（Ⅰ）和金（Ⅲ）氮杂环卡宾配合物的催化活性都远高于我们之前测试的N,N-和P,N-配位的金（Ⅲ）配合物。金（Ⅰ）和金（Ⅲ）的对比催化研究表明，催化能力不同，这取决于氮杂环卡宾配体的灵活性和体积大小。使用带有庞大的基于N1-Mes-N2-乙醇的氮杂环卡宾配体的金（Ⅰ）和金（Ⅲ）配合物，均可获得目标烷氧基环化产物的优异产率（92 - 99%）。
