Highly strained 2H‐azirines with a tetrasubstituted stereocenter were synthesized by the enantioselective isomerization of isoxazoles with a chiral diene–rhodium catalyst system. The effect of ligands and the coordination behavior support the proposed catalytic cycle in which the coordination site is fixed in favor of efficient enantiodiscrimination by a bulky substituent of the ligand. In silico studies
6‐bis(oxazoline) (pybox) ligands for asymmetric transition metal catalysis is introduced by adding a bidentate ligand to modulate the electronic properties and asymmetric induction. Specifically, a ruthenium(II) pybox fragment is combined with a cyclometalated N‐heterocyclic carbene (NHC) ligand to generate catalysts for enantioselective transition metal nitrenoid chemistry, including ring contraction
通过添加双齿配体来调节电子性质和不对称诱导,提出了扩大手性吡啶-2,6-双(恶唑啉)(pybox)配体在不对称过渡金属催化中的应用的策略。具体来说,钌 (II) pybox 片段与环金属化 N-杂环卡宾 (NHC) 配体结合,生成用于对映选择性过渡金属氮烯化学的催化剂,包括环收缩为手性 2H-氮丙啶(2000 TON 时高达 97% ee)和对映选择性 C(sp 3 )−H 胺化(50 TON 时高达 97 % ee)。
Trading Symmetry for Stereoinduction in Tetradentate, non‐<i>C</i><sub>2</sub>‐Symmetric Fe(II)‐Complexes for Asymmetric Catalysis
作者:Philipp S. Steinlandt、Marcel Hemming、Xiulan Xie、Sergei I. Ivlev、Eric Meggers
DOI:10.1002/chem.202300267
日期:2023.6.7
A series of C1-symmetric bench-stable stereogenic-at-iron complexes comprising a linear, tetradentate ligand scaffold are introduced. The possibility of lowering the overall symmetry is scrutinized for an enantioselective ring-contraction of isoxazoles to furnish chiral 2H-azirines under open-flask conditions with the products serving as useful building blocks to access α-disubstituted α-amino acid
介绍了一系列包含线性四齿配体支架的 C 1对称稳定型铁立体异构复合物。降低整体对称性的可能性被仔细检查异恶唑的对映选择性缩环以在开放烧瓶条件下提供手性 2 H-氮杂环丙烷,产物用作获得 α-二取代的 α-氨基酸衍生物的有用构建单元。