Copper-Catalyzed N-N Bond Formation by Homocoupling of Ketoximes via N-O Bond Cleavage: Facile, Mild, and Efficient Synthesis of Azines
摘要:
A facile, mild, and efficient copper-catalyzed homocoupling of ketoximes involving N-O bond cleavage in the presence of sodium bisulfite (NaHSO3) has been developed. This reaction shows good functional group tolerance and affords a broad scope of azines in high yields.
One-Pot Transformation of Ketoximes into Optically Active Alcohols and Amines by Sequential Action of Laccases and Ketoreductases or ω-Transaminases
作者:Raquel S. Correia Cordeiro、Nicolás Ríos-Lombardía、Francisco Morís、Robert Kourist、Javier González-Sabín
DOI:10.1002/cctc.201801900
日期:2019.2.20
An enzymatic one‐pot process for asymmetric transformation of prochiral ketoximes into alcohols or amines was developed by sequential coupling of a laccase‐catalyzed deoximation either with a ketone reduction (ketoreductase, KRED) or bioamination (ω‐transaminase, ω‐TA) in aqueous medium. An accurate selection of biocatalysts provided the corresponding products in excellent enantiomeric excesses and
A novel protocol for the efficient activation of the Beckmannrearrangement utilizing the readily available sulfuryl fluoride (SO2F2 gas) is reported. The substrate scope of this methodology has been demonstrated by 37 examples with good to nearly quantitative isolated yields in a short time. A tentative mechanism was proposed involving formation and elimination of sulfonyl ester.
报道了一种利用容易获得的硫酰氟(SO 2 F 2气体)有效激活贝克曼重排的新方案。该方法的底物范围已通过37个实例证明,并在短时间内获得了良好至近乎定量的分离产率。提出了一种尝试性的机制,涉及形成和消除磺酰基酯。
<i>N</i>,<i>N</i>′-Dioxide−Cu(OTf)<sub>2</sub> Complex Catalyzed Highly Enantioselective Amination Reaction of <i>N</i>-Acetyl Enamide
The N,N′-dioxide−Cu(OTf)2complexes were applied in the asymmetric amination reaction of N-acetyl enamides with dialkyl azodicarboxylate, giving the corresponding products in good yields with high enantioselectivities (up to 91% ee). Precursors of vicinal diamine were readily obtained with excellent diastereoselectivities (>95:5) by NaBH4 reduction.
The deoximation of a wide range of ketoximes and aldoximes to their corresponding carbonyl compounds with high yields has been achieved usinggrapheneoxide (GO) and sodium nitrite (NaNO2) as highly efficient catalysts and air as the green oxidant under mild conditions. The mechanism of deprotection and recycling use of catalyst were revealed in deep experiment. The carboxylic acid groups on the GO
We report realization of the first enantioselective Cope-type hydroamination of oximes for asymmetric nitrone synthesis. The ligand promoted asymmetriccyclopropene “hydronitronylation” process employs a Cu-based catalytic system and readily available starting materials, operates under mild conditions and displays broad scope and exceptionally high enantio- and diastereocontrol. Preliminary mechanistic