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)。
The tautomerism of heteroaromatic compounds with five-membered rings—I
作者:A.J. Boulton、A.R. Katritzky
DOI:10.1016/0040-4020(61)80097-5
日期:1961.1
Infra-red and ultra-violet spectra show that 3,4-dimethyl-5-hydroxyisoxazole exists in aqueous and chloroform solution, and in the solid phase in the OH form; and that 3-phenyl-, 4-bromo-3-phenyl-, and 4-methyl-3-phenyl-isoxazol-5-ones exist as mixtures of the CH and NH forms in solution, the proportion of the NH form increasing with the polarity of the solvent. The basicities of isoxazole and some
the synthesis of azirine-2-carboxylates from non-halogenated 5-alkoxyisoxazoles. A convenient gram-scale method for the preparation of 2-halo-2H-azirine-2-carboxylic acidesters, thioesters and amides via metal-catalyzed isomerization of 5-heteroatom-substituted 4-haloisoxazoles is developed. The formation of the esters and amides is efficiently catalyzed by Rh2(Piv)4, while FeCl2·4H2O is the catalyst
One-Pot Synthesis of Multifunctionalized 1-Pyrrolines from 2-Alkyl-2<i>H</i>-azirines and Diazocarbonyl Compounds
作者:Ilya P. Filippov、Mikhail S. Novikov、Alexander F. Khlebnikov、Nikolai V. Rostovskii
DOI:10.1021/acs.joc.2c00977
日期:2022.7.1
the synthesis of 1-pyrrolines based on formal [4 + 1] annulation of 2-alkyl-2H-azirines with diazocarbonyl compounds has been developed. This one-pot approach includes the Rh(II)-catalyzed formation of 4-alkyl-2-azabuta-1,3-dienes, followed by the DBU-promoted cyclization, and features a good substrate tolerance. The 1-pyrrolines containing an ester group at the C3 were prepared in a three-step one-pot
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。