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81.
A new palladium-catalyzed C-H amination of aryl enamines for the synthesis of trifluoromethylated indoles is established. The attractive features of this transformation are the use of atom-economical O2 as the oxidant and easily prepared enamines as substrates. A variety of pharmaceutically important 2-trifluoromethyl indoles can be targeted in moderate to good yields with good functional compatibility. 相似文献
82.
Fabio Bellina 《Tetrahedron》2008,64(26):6060-6072
Highly selective, practical, and efficient protocols for the preparation of 4(5)-aryl-1H-imidazoles 2, 2,4(5)-diaryl-1H-imidazoles 3, and 4,5-diaryl-1H-imidazoles 1 are described. A key step of these protocols is the regioselective synthesis of 5-aryl-1-benzyl-1H-imidazoles 9 by Pd-catalyzed direct C-5 arylation of commercially available 1-benzyl-1H-imidazole (8) with aryl halides. The three-step synthesis of compounds 3 from 8 also involves the Pd-catalyzed and Cu-mediated direct C-2 arylation of imidazoles 9 with aryl halides under base-free and ligandless conditions. On the other hand, the four-step synthesis of imidazoles 1 from 8 also involves the regioselective bromination of compounds 9 and a Suzuki reaction of the resulting 5-aryl-1-benzyl-4-bromo-1H-imidazoles 11 with arylboronic acids 5 under phase-transfer conditions, followed by N-debenzylation. 相似文献
83.
Behrouz Notash Hamid Reza Khavasi Vahid Amani Anita Abedi 《Journal of organometallic chemistry》2008,693(24):3553-3557
Two novel organometallic complex of 2,2′-dimethyl-4,4′-bithiazole (dm4bt) ligand (L) with formula [Tl(dm4bt)2(NO3)(H2O)] (1) and [Tl(dm4bt)2(NO3)(DMSO)] (2) have been synthesized and structurally characterized by elemental analysis, FT-IR, 1H NMR spectra and X-ray crystallography. These complexes also display the first transoid conformation in bithiazole ligands in which C-H bond activation in bithiazole ring is observed with Tl(III) ion. 相似文献
84.
Manisha Devesh Chandra Prof. Dr. Upendra Sharma 《European journal of organic chemistry》2023,26(30):e202300411
An efficient Rh(III)-catalyzed C−H alkenylation of N-protected isoquinolone with maleimides is reported. The carbonyl group of isoquinolone acts as an inherent directing group. Various N-substituents in the maleimide, including alkyl, aryl, and even H and −OH, were well tolerated under the developed reaction condition. This protocol showed broad substrate scope, good selectivity, and excellent yields. Hammett plot is also drawn to check the effect of substituents on the reaction progress. 相似文献
85.
以二叔丁基过氧化物(DTBP)为氧化剂,苯硫酚为硫化试剂,在无金属参与的条件下,于120℃下采用一步法合成了硫代苄醚.这种构筑C(sp~3)—S键的方法具有高原子经济性和高选择性的优点,并以较高的收率获得了一系列目标化合物. 相似文献
86.
Treatment of [RuCl3(PPh3)3] with 1-(arylazo)naphthol ligands in benzene under reflux afford air-stable new organoruthenium(III) complexes with general composition [Ru(an-R)Cl(PPh3)2] (where, R = H, Cl, CH3, OCH3, OC2H5) in fairly good yield. The 1-(arylazo)naphtholate ligands behave as dianionic tridentate C, N, O donors and coordinates to ruthenium through phenolic oxygen, azo nitrogen and ortho carbon generate two five-membered chelate rings. The composition of the complexes have been established by analytical (elemental analysis and magnetic susceptibility measurement) and spectral (FT-IR, UV-Vis, EPR) methods. The complexes are paramagnetic (low-spin, d5) in nature and in dichloromethane solution show intense d-d transitions and ligand-to-metal charge transfer (LMCT) transitions in the visible region. The solution EPR spectrum of complex [Ru(an-CH3)Cl(PPh3)2] (3) in dichloromethane at 77 K shows rhombic distortion around the ruthenium ion with three different ‘g’ values (gx ≠ gy ≠ gz). The single crystal structure of the complex [Ru(an-OCH3)Cl(PPh3)2] (4) has been characterised by X-ray crystallography, indicates the presence of a distorted octahedral geometry in these complexes. All the complexes exhibit one quasi-reversible oxidative response in the range 0.60-0.79 V (RuIV/RuIII) and two quasi-reversible reductive responses (RuIII/RuII; RuII/RuI) within the range −0.50 to −0.62 V and −0.93 to −0.98 V respectively. The formal potential of all the couples correlate linearly with the Hammett constant of the para substituent in arylazo fragment of the 1-(arylazo)naphtholate ligand. Further, the catalytic efficiency of one of the ruthenium complexes (4) was determined for the transfer hydrogenation of ketones with an excellent yield up to 99% in the presence of isopropanol/KOH. 相似文献
87.
The frequency response characteristics for twenty-two organic vapours by piezoelectric thickness-shear-mode (TSM) acoustic wave sensors coated with four supramolecule compounds—calixarenes have been investigated. Among them, 2,8,14,20-tetraethyl-4,6,10,12,16,18,22,24-octahydroxylcalix[4]arene (I) was the most efficient actively adsorptive material for host-guest recognizing alkyl ketone molecules such as 2-butanone and acetone. The supramolecule recognition mechanism has been discussed, that is based on the formation of C-H?π bond interaction between the methyl group of ketone molecule and the phenyl ring of the calixarene compound. The linear range of the TSM sensor upon exposure to 2-butanone vapour was 0-940.5 ppm with a detection limit of 2.67 ppm when the coating mass of the compound I was selected as 19 μg. The kinetics behaviours in the adsorption and desorption processes have been examined with polynomial curve fitting procedure. Furthermore, the proposed TSM sensor possessed good selectivity, reversibility, reproducibility and high stability. Compared with gas chromatography (GC) method, the proposed sensor can be used for on-line determination of 2-butanone vapour in air with a recovery of 94.8-106.5%, which was in consistent with those obtained by GC method. 相似文献
88.
Soukaina Faarasse Nabil El Brahmi Grald Guillaumet Saïd El Kazzouli 《Molecules (Basel, Switzerland)》2021,26(19)
The regioselective C-H functionalization of the five-membered ring of the 6,5-fused heterocyclic systems is nowadays well documented due to its high reactivity compared to the six-membered ring. So, developing new procedures of C-H functionalization of the six-membered ring “by thinking out of the box” is extremely challenging, which explains the limited number of reports published to date. This review paper aims to highlight advances achieved in this emerging chemistry research and discusses recently reported methods. 相似文献
89.
90.
含氮饱和杂环化合物,如β-内酰胺、氮杂环丙烷、四氢吡咯、哌啶及其苯并骨架吲哚啉、四氢喹啉、四氢异喹啉等结构单元是天然产物和药物分子中常见的"优势骨架",在新药的发现中起到了极其重要的作用.配位导向的非活化C(sp3)-H键的直接胺化方法可高效构建C-N键,是C-H键活化反应方法学的重要研究内容之一.本文介绍了近期配位导向的非活化C(sp3)-H键的分子内直接胺化策略构建含氮杂环的新进展,其中包括双齿、单齿和分子内本身的二级胺作为定位基参与的活化模式,探讨了其反应机制、选择性、底物的适用性及其在合成中的应用. 相似文献