5856-79-1Relevant academic research and scientific papers
Pd/Cu-Catalyzed Cascade C(sp3)-H Arylation and Intramolecular C-N Coupling: A One-Pot Synthesis of 3,4-2 H-Quinolinone Skeletons
Xiao, Han-Zhi,Wang, Wen-Shu,Sun, Yu-Song,Luo, Hao,Li, Bo-Wen,Wang, Xiao-Dong,Lin, Wei-Li,Luo, Fei-Xian
supporting information, p. 1668 - 1671 (2019/03/11)
In this letter, we successfully explored a cascade Pd/Cu-catalyzed intermolecular C(sp3)-H arylation of amides and intramolecular C-N coupling reaction. This method provides a one-pot strategy to synthesize 3,4-2H-quinolinone with good regioselectivity of C-H arylation and C-N coupling from C-I and C-X bonds from readily available starting materials.
2-Amino-5,6-difluorophenyl-1 H-pyrazole-Directed PdII Catalysis: Arylation of Unactivated β-C(sp3)-H Bonds
Yang, Jinyue,Fu, Xiaopan,Tang, Shibiao,Deng, Kezuan,Zhang, Lili,Yang, Xianjin,Ji, Yafei
, p. 10221 - 10236 (2019/08/20)
Palladium-catalyzed arylation of unactivated β-C(sp3)-H bonds in carboxylic acid derivatives with aryl iodides is described for the first time using 2-amino-5,6-difluorophenyl-1H-pyrazole as an efficient and readily removable directing group. Two fluoro groups are installed at the 5- and 6-position of the anilino moiety in 2-aminophenyl-1H-pyrazole, clearly enhancing the directing ability of the auxiliary. In addition, the protocol employs Cu(OAc)2/Ag3PO4 (1.2/0.3) as additives, evidently reducing the stoichiometric amount of expensive silver salts. Furthermore, this process exhibits high β-site selectivity, compatibility with diverse substrates containing α-hydrogen atoms, and excellent functional group tolerance.
Stereocontrol in Preparation of Cyclopalladated Alkylaromatic Oximes and Evaluation of Their Stereoselective Esterase-Type Catalytic Activity
Vatsadze, Sergey Z.,Medved'Ko, Aleksei V.,Kurzeev, Sergey A.,Pokrovskiy, Oleg I.,Parenago, Olga O.,Kostenko, Mikhail O.,Ananyev, Ivan V.,Lyssenko, Konstantin A.,Lemenovsky, Dmitri A.,Kazankov, Gregory M.,Lunin, Valery V.
, p. 3068 - 3075 (2017/09/05)
The stereochemistry of 2′-methylbutyrophenone oxime, the rates of ortho-palladation of its E- and Z-isomers, and catalytic activity of the respective Pd complexes were studied. The full stereoisomeric composition of oximes was established for the first time by means of supercritical fluid chromatography on chiral polysaccharide column. It was shown that enantiomeric excesses of both E/Z-isomers of (S)-2′-methylbutyrophenone oxime (1S) and (R)-2′-methylbutyrophenone oxime (1R) were equal to 92 ± 2. The cyclopalladation study revealed that while E-isomer is ortho-palladated very quickly its Z-counterpart does not enter this reaction. However, upon coordination to Pd(II), Z-oxime slowly isomerizes into E-form with fast subsequent cyclopalladation, so it was possible to perform ortho-palladation of E-oxime in kinetic resolution mode with removal of unreacted Z-oxime. Comparatively rare cis-structure of cyclopalladated oxime dimer was proved by means of single-crystal X-ray study. For the first time, it was shown that ortho-palladated chiral oximes behave as enantioselective catalyst in the hydrolysis of chiral esters.
Ligand-enabled β-C-H arylation of α-amino acids using a simple and practical auxiliary
Chen, Gang,Shigenari, Toshihiko,Jain, Pankaj,Zhang, Zhipeng,Jin, Zhong,He, Jian,Li, Suhua,Mapelli, Claudio,Miller, Michael M.,Poss, Michael A.,Scola, Paul M.,Yeung, Kap-Sun,Yu, Jin-Quan
supporting information, p. 3338 - 3351 (2015/03/30)
Pd-catalyzed β-C-H functionalizations of carboxylic acid derivatives using an auxiliary as a directing group have been extensively explored in the past decade. In comparison to the most widely used auxiliaries in asymmetric synthesis, the simplicity and practicality of the auxiliaries developed for C-H activation remains to be improved. We previously developed a simple N-methoxyamide auxiliary to direct β-C-H activation, albeit this system was not compatible with carboxylic acids containing α-hydrogen atoms. Herein we report the development of a pyridine-type ligand that overcomes this limitation of the N-methoxyamide auxiliary, leading to a significant improvement of β-arylation of carboxylic acid derivatives, especially α-amino acids. The arylation using this practical auxiliary is applied to the gram-scale syntheses of unnatural amino acids, bioactive molecules, and chiral bis(oxazoline) ligands.
Pd(II)-Catalyzed Direct Sulfonylation of Unactivated C(sp3)-H Bonds with Sodium Sulfinates
Rao, Wei-Hao,Zhan, Bei-Bei,Chen, Kai,Ling, Peng-Xiang,Zhang, Zhuo-Zhuo,Shi, Bing-Feng
supporting information, p. 3552 - 3555 (2015/07/28)
A Pd(II)-catalyzed sulfonylation of unactivated C(sp3)-H bonds with sodium arylsulfinates using an 8-aminoquinoline auxiliary is described. This reaction demonstrates excellent functional group tolerance with respect to both the caboxamide starting material and the sodium arylsulfinate coupling partner, affording a broad range of aryl alkyl sulfones. Moreover, the late-stage modification of complex molecules was achieved via this sulfonylation protocol.
Unactivated C(sp3)-H hydroxylation through palladium catalysis with H2O as the oxygen source
Hu, Jiantao,Lan, Tianlong,Sun, Yihua,Chen, Hui,Yao, Jiannian,Rao, Yu
supporting information, p. 14929 - 14932 (2015/10/06)
A novel palladium catalyzed hydroxylation of unactivated aliphatic C(sp3)-H bonds was successfully developed. Different from conventional methods, water serves as the hydroxyl group source in the reaction. This new reaction demonstrates good reactivity and broad functional group tolerance. The C-H hydroxylated products can be readily transformed into various highly valuable chemicals via known transformations. Based on experimental and theoretical studies, a mechanism involving the Pd(ii)/(iv) pathway is proposed for this hydroxylation reaction.
An LC-MS/MS method to quantify acylcarnitine species including isomeric and odd-numbered forms in plasma and tissues
Giesbertz, Pieter,Ecker, Josef,Haag, Alexander,Spanier, Britta,Daniel, Hannelore
, p. 2029 - 2039 (2015/11/17)
Acylcarnitines are intermediates of fatty acid and amino acid oxidation found in tissues and body fluids. They are important diagnostic markers for inherited diseases of peroxisomal and mitochondrial oxidation processes and were recently described as biomarkers of complex diseases like the metabolic syndrome. Quantification of acylcarnitine species can become challenging because various species occur as isomers and/or have very low concentrations. Here we describe a new LC-MS/MS method for quantification of 56 acylcarnitine species with acyl-chain lengths from C2 to C18. Our method includes amino acid-derived positional isomers, like methacrylyl-carnitine (2-M-C3:1-CN) and crotonyl-carnitine (C4:1-CN), and odd-numbered carbon species, like pentadecanoyl-carnitine (C15:0-CN) and heptadecanoyl-carnitine (C17:0-CN), occurring at very low concentrations in plasma and tissues. Method validation in plasma and liver samples showed high sensitivity and excellent accuracy and precision. In an application to samples from streptozotocin-treated diabetic mice, we identified significantly increased concentrations of acylcarnitines derived from branched-chain amino acid degradation and of odd-numbered straight-chain species, recently proposed as potential biomarkers for the metabolic syndrome. In conclusion, the LC-MS/MS method presented here allows robust quantification of isomeric acylcarnitine species and extends the palette of acylcarnitines with diagnostic potential derived from fatty acid and amino acid metabolism.
Isolation and synthesis of N-acyladenine and adenosine alkaloids from a southern Australian marine sponge, Phoriospongia sp.
Farrugia, Michelle,Trotter, Nicholas,Vijayasarathy, Soumini,Salim, Angela A.,Khalil, Zeinab G.,Lacey, Ernest,Capon, Robert J.
supporting information, p. 5902 - 5904 (2014/12/11)
Chemical fractionation of the southern Australian marine sponge Phoriospongia sp. (CMB-03107) yielded phorioadenine A (1) as a nematocidal agent and the first reported example of a 6-N-acyladenine natural product. The structure of 1 was confirmed by spectroscopic analysis and the chemical synthesis of racemic (1a) and enantiomeric (1b) analogues. HPLC-ESIMS analysis of the crude sponge extract with comparisons to the synthetic 6-N-acyladenosine 2a provided evidence that the biosynthetically related adenosine, phorioadenosine A (2), was present as a trace co-metabolite. The rare starfish metabolite asterubine (3) was also isolated as a co-metabolite, and its structure confirmed by spectroscopic analysis and chemical synthesis. Biological investigations confirmed that natural products 1-3 and synthetic analogues 1a-e and 2a were not cytotoxic to multiple mammalian cancer cell lines, or Gram-positive or -negative bacteria. Nematocidal activity (inhibition of larval development of Haemonchus contortus) detected in the Phoriospongia sp. extract was attributed to 1 (LD9931 μg/mL), with preliminary structure-activity relationship investigations confirming the importance of the N-acyl side chain.
Ligand-promoted alkylation of C(sp3)-H and C(sp2)-H bonds
Zhu, Ru-Yi,He, Jian,Wang, Xiao-Chen,Yu, Jin-Quan
supporting information, p. 13194 - 13197 (2015/03/30)
9-Methylacridine was identified as a generally effective ligand to promote a Pd(II)-catalyzed C(sp3) - H and C(sp2) - H alkylation of simple amides with various alkyl iodides. This alkylation reaction was applied to the preparation of unnatural amino acids and geometrically controlled tri- and tetrasubstituted acrylic acids.
Memory of chirality in rebound cyclizations of α-amide radicals
Sasmal, Aniruddha,Taniguchi, Tsuyoshi,Wipf, Peter,Curran, Dennis P.
supporting information, p. 1 - 5 (2013/03/13)
Reduction of (S)-N-(2-bromoallyl)-N-(tert-butyl)-2-methyl-3- phenylpropanamide with tributyltin hydride provides (3S,4S)-3-benzyl-1-(tert- butyl)-3,4-dimethylpyrrolidin-2-one with about 80% retention of chirality at the stereocenter adjacent to the amide carbonyl group. This memory of chirality is suggested to occur by transfer of chirality from a stereocenter to an axis, then from the axis back to a new stereocenter.
