2647-04-3Relevant academic research and scientific papers
Determining the Enantiomeric Excess and Absolute Configuration of in Situ Fluorine-Labeled Amines and Alcohols by 19F NMR Spectroscopy
Jang, Sumin,Park, Hahyoun,Duong, Quynh Huong,Kwahk, Eun-Jeong,Kim, Hyunwoo
, p. 1441 - 1446 (2022/01/11)
The determination of the enantiomeric excess and absolute configuration of chiral compounds is indispensable in synthetic, pharmaceutical, and biological chemistry. In this article, we describe an efficient 19F nuclear magnetic resonance (NMR)-based analytical protocol for determining the enantiomeric excess and absolute configuration of in situ fluorine-labeled amines and alcohols. 2-Fluorobenzoylation was used to convert analytes to fluorinated amides or esters. The resulting F-labeled analytes were mixed with a cationic cobalt(III) complex, [Co]BArF, resulting in clean baseline peak separations of analyte enantiomers in 19F{1H} NMR spectra. The measured ΔδRS signs were unambiguously used to correlate the absolute configurations of amines, amino alcohols, and alcohols. Moreover, the structure-dependent 19F{1H} NMR signals enabled absolute configuration determination by analyzing the relative chemical shifts of enantiopure analyte samples with [Co]BArF and ent-[Co]BArF.
Copper-Catalyzed C(sp3)?H Amidation: Sterically Driven Primary and Secondary C?H Site-Selectivity
Bakhoda, Abolghasem (Gus),Jiang, Quan,Badiei, Yosra M.,Bertke, Jeffery A.,Cundari, Thomas R.,Warren, Timothy H.
supporting information, p. 3421 - 3425 (2019/02/14)
Undirected C(sp3)?H functionalization reactions often follow site-selectivity patterns that mirror the corresponding C?H bond dissociation energies (BDEs). This often results in the functionalization of weaker tertiary C?H bonds in the presence of stronger secondary and primary bonds. An important, contemporary challenge is the development of catalyst systems capable of selectively functionalizing stronger primary and secondary C?H bonds over tertiary and benzylic C?H sites. Herein, we report a Cu catalyst that exhibits a high degree of primary and secondary over tertiary C?H bond selectivity in the amidation of linear and cyclic hydrocarbons with aroyl azides ArC(O)N3. Mechanistic and DFT studies indicate that C?H amidation involves H-atom abstraction from R-H substrates by nitrene intermediates [Cu](κ2-N,O-NC(O)Ar) to provide carbon-based radicals R. and copper(II)amide intermediates [CuII]-NHC(O)Ar that subsequently capture radicals R. to form products R-NHC(O)Ar. These studies reveal important catalyst features required to achieve primary and secondary C?H amidation selectivity in the absence of directing groups.
Nickel/Briphos-Catalyzed Direct Transamidation of Unactivated Secondary Amides Using Trimethylsilyl Chloride
Yu, Subeen,Shin, Taeil,Zhang, Maosheng,Xia, Yuanzhi,Kim, Hyunwoo,Lee, Sunwoo
supporting information, p. 7563 - 7566 (2019/01/03)
Direct transamidation of secondary amides was developed via nickel catalysis. In the presence of trimethylsilyl chloride and manganese, Ni(diglyme)Cl2 with a Briphos ligand efficiently promoted the transamidation of N-aryl benzamide derivatives with primary amines to afford the corresponding secondary amides in moderate to good yields. Primary amines bearing electron-donating groups gave higher yields of the transamidation products.
Copper-Catalyzed Reductive N-Alkylation of Amides with N-Tosylhydrazones Derived from Ketones
Xu, Peng,Qi, Fu-Ling,Han, Fu-She,Wang, Yan-Hua
, p. 2030 - 2034 (2016/07/28)
A CuI-catalyzed reductive coupling of ketone-derived N-tosylhydrazones with amides is presented. Under the optimized conditions, an array of N-tosylhydrazones derived from aryl–alkyl and diaryl ketones could couple effectively with a wide variety of (hete
Selective catalytic Hofmann: N -alkylation of poor nucleophilic amines and amides with catalytic amounts of alkyl halides
Xu, Qing,Xie, Huamei,Zhang, Er-Lei,Ma, Xiantao,Chen, Jianhui,Yu, Xiao-Chun,Li, Huan
supporting information, p. 3940 - 3944 (2016/07/21)
Using only catalytic amounts of alkyl halides in the reactions of poor nucleophilic amines/amides and alcohols led to a selective Hofmann N-alkylation reaction catalytic in alkyl halides, providing a practical and efficient method for the practical synthesis of mono- or di-alkylated amines/amides in high selectivities. This new method avoids the use of large amounts of bases, alkyl halides, and solvents, and generates water as the only byproduct. Preliminary mechanistic studies showed that alkyl halides are key intermediates/catalysts regeneratable in the reaction cycle.
Au(iii)-catalyzed intermolecular amidation of benzylic C-H bonds
Zhang, Yan,Feng, Bainian,Zhu, Chengjian
supporting information, p. 9137 - 9141,5 (2012/12/12)
Au(iii)-catalyzed intermolecular amidations of benzylic C-H bonds with sulfonamides and carboxamides are described. The protocol with the Au-bipy complex/N-bromosuccinimide system provides practical applications for synthesis of various amides via C-H activations. The reaction proceeds with high efficiency to give the corresponding amines, which are extremely useful synthetic intermediates.
Efficient intermolecular iron-catalyzed amidation of C-H bonds in the presence of n-bromosuccinimide
Wang, Zhe,Zhang, Yongming,Fu, Hua,Jiang, Yuyang,Zhao, Yufen
supporting information; experimental part, p. 1863 - 1866 (2009/04/12)
We have developed an efficient, inexpensive, and air-stable catalyst/oxidant (FeCI2/NBS) system that could efficiently promote amidation of benzylic sp3 C-H bonds in ethyl acetate under mild conditions.
