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111.
José A. Forni Nenad Micic Dr. Timothy U. Connell Dr. Geethika Weragoda Dr. Anastasios Polyzos 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18805-18813
We report a new visible-light-mediated carbonylative amidation of aryl, heteroaryl, and alkyl halides. A tandem catalytic cycle of [Ir(ppy)2(dtb-bpy)]+ generates a potent iridium photoreductant through a second catalytic cycle in the presence of DIPEA, which productively engages aryl bromides, iodides, and even chlorides as well as primary, secondary, and tertiary alkyl iodides. The versatile in situ generated catalyst is compatible with aliphatic and aromatic amines, shows high functional-group tolerance, and enables the late-stage amidation of complex natural products. 相似文献
112.
Susith R. Galle Kankanamge Jianbo Ma Dr. Robert T. Mackin Dr. Fedra M. Leonik Prof. Carol M. Taylor Prof. Igor V. Rubtsov Prof. Daniel G. Kuroda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17160-17165
Hydrogen bonds (H bonds) play a major role in defining the structure and properties of many substances, as well as phenomena and processes. Traditional H bonds are ubiquitous in nature, yet the demonstration of weak H bonds that occur between a highly polarized C−H group and an electron-rich oxygen atom, has proven elusive. Detailed here are linear and nonlinear IR spectroscopy experiments that reveal the presence of H bonds between the chloroform C−H group and an amide carbonyl oxygen atom in solution at room temperature. Evidence is provided for an amide solvation shell featuring two clearly distinguishable chloroform arrangements that undergo chemical exchange with a time scale of about 2 ps. Furthermore, the enthalpy of breaking the hydrogen bond is found to be 6–20 kJ mol−1. Ab-initio computations support the findings of two distinct solvation shells formed by three chloroform molecules, where one thermally undergoes hydrogen-bond making and breaking. 相似文献
113.
本文综合评述了近年来2-[2-(二环己膦基)苯基]-1-甲基-1H-吲哚(CM-Phos)膦配体及其衍生物在钯催化的交叉偶联反应中的应用, 主要根据不同种类的交叉偶联反应进行系统性分述, 并对该领域的发展前景进行了展望. 相似文献
114.
Srinivas Cheruku Chaithra Nagaraju Poornima Shetty Swarup Hassan A Sandhya Nagarakere C 《合成通讯》2020,50(10):1486-1494
AbstractWe have developed an economical and efficient method for the synthesis of medicinally and synthetically important indole-based triarylmethanes by using indoles and benzhydrols in the presence of propylphosphonic anhydride (T3P®). This methodology is an alternate approach for the C–C bond formation with good to excellent yields. In this T3P-mediated dehydration approach, the by-product is highly soluble in water, so that it can be done at larger scale also. In addition to that this efficient protocol has several advantages such as mild reaction conditions, short reaction time and operational simplicity. We have successfully synthesized pyrrole, imidazothiadiazole and imidazolo pyridine based triarylmethanes also. 相似文献
115.
Therese Planke Katarina Cirnski Dr. Jennifer Herrmann Prof. Dr. Rolf Müller Prof. Dr. Andreas Kirschning 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4289-4296
Cystobactamids belong to the group of arene-based oligoamides that effectively inhibit bacterial type IIa topoisomerases. Cystobactamid 861-2 is the most active member of these antibiotics. Most amide bonds present in the cystobactamids link benzoic acids with anilines and it was found that some of these amide bonds undergo chemical and enzymatic hydrolysis, especially the one linking ring C with ring D. This work reports on the chemical synthesis and biological evaluation of thirteen new cystobactamids that still contain the methoxyaspartate hinge. However, we exchanged selected amide bonds either by the urea or the triazole groups and modified ring A in the latter case. While hydrolytic stability could be improved with these structural substitutes, the high antibacterial potency of cystobactamid 861-2 could only be preserved in selected cases. This includes derivatives, in which the urea group is positioned between rings A and B and where the triazole is found between rings C and D. 相似文献
116.
ukasz Balewski Franciszek Sczewski Patrick J. Bednarski Lisa Wolff Anna Nadworska Maria Gdaniec Anita Kornicka 《Molecules (Basel, Switzerland)》2020,25(24)
The appropriate 1-arylhydrazinecarbonitriles 1a–c are subjected to the reaction with 2-chloro-4,5-dihydro-1H-imidazole (2), yielding 7-(4,5-dihydro-1H-imidazol-2-yl)-2-aryl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-imines 3a–c, which are subsequently converted into the corresponding amides 4a–e, 8a–c, sulfonamides 5a–n, 9, ureas 6a–I, and thioureas 7a–d. The structures of the newly prepared derivatives 3a–c, 4a–e, 5a–n, 6a–i, 7a–d, 8a–c, and 9 are confirmed by IR, NMR spectroscopic data, as well as single-crystal X-ray analyses of 5e and 8c. The in vitro cytotoxic potency of these compounds is determined on a panel of human cancer cell lines, and the relationships between structure and antitumor activity are discussed. The most active 4-chloro-N-(2-(4-chlorophenyl)-7-(4,5-dihydro-1H-imidazol-2-yl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)benzamide (4e) and N-(7-(4,5-dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)-[1,1′-biphenyl]-4-sulfonamide (5l) inhibits the growth of the cervical cancer SISO and bladder cancer RT-112 cell lines with IC50 values in the range of 2.38–3.77 μM. Moreover, N-(7-(4,5-dihydro-1H-imidazol-2-yl)-2-phenyl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)-4-phenoxybenzenesulfonamide (5m) has the best selectivity towards the SISO cell line and induces apoptosis in this cell line. 相似文献
117.
Moritz Balkenhohl Harish Jangra Ilya S. Makarov Shu‐Mei Yang Hendrik Zipse Paul Knochel 《Angewandte Chemie (International ed. in English)》2020,59(35):14992-14999
The development of a predictive model towards site‐selective deprotometalation reactions using TMPZnCl?LiCl is reported (TMP=2,2,6,6‐tetramethylpiperidinyl). The pKa values of functionalized N‐, S‐, and O‐heterocycles, arenes, alkenes, or alkanes were calculated and compared to the experimental deprotonation sites. Large overlap (>80 %) between the calculated and empirical deprotonation sites was observed, showing that thermodynamic factors strongly govern the metalation regioselectivity. In the case of olefins, calculated frozen state energies of the deprotonated substrates allowed a more accurate prediction. Additionally, various new N‐heterocycles were analyzed and the metalation regioselectivities rationalized using the predictive model. 相似文献
118.
We have developed a facile and efficient procedure for the synthesis of diarylphosphate esters and amides. Using Zn(acac)2 as the catalyst, the reaction of diarylphosphoryl azides with aliphatic alcohols and phenols through an unusual P?N bond cleavage provided a number of diarylphosphate esters in good yields (22 examples, up to 94%). Additionally, various diarylphosphate amides were obtained from the corresponding amines in excellent yields as well (8 examples, up to 96%). 相似文献
119.
Francesco A. Bottino Giovanna Di Pasquale Nicoletta Leonardi Antonino Pollicino 《Journal of polymer science. Part A, Polymer chemistry》1996,34(7):1305-1310
High molecular-weight aromatic polyamides were obtained from 1,5- and 2,6-bis-(4′-carboxy-4-phenylenoxy-sulfonyl)naphthalene by direct polycondensation reaction in N-methyl-2-pyrrolidone with various aromatic diamines, using triphenyl phosphite and pyridine as condensing agents. The polymers were characterized by elemental analysis, thermogravimetric analysis, differential scanning calorimetry, and infrared analysis. The polyamides, obtained in quantitative yield, possessed inherent viscosities in the range 0.42–1.70 dL/g, glass transition temperatures between 245–310°C, and 10% weight loss temperatures in nitrogen and air above 435 and 424°C, respectively. Most of the polymers were soluble in aprotic solvents. The effect of the structure on properties, such as solubility, Tg, and thermal behavior, were also studied. © 1996 John Wiley & Sons, Inc. 相似文献
120.
Mahmoud Sunjuk Mousa Al-Noaimi Ghassan Abu Sheikha Ekkehard Lindner Bassam El-Eswed Kamal Sweidan 《Polyhedron》2009
Water-soluble functionalized bis(phosphine) ligands L (a–h) of the general formula CH2(CH2PR2)2, where for a: R = (CH2)6OH; b–g: R = (CH2)nP(O)(OEt)2, n = 2–6 and n = 8; h: R = (CH2)3NH2 ( Scheme 1), have been prepared photochemically by hydrophosphination of the corresponding 1-alkenes with H2P(CH2)3PH2. Water-soluble palladium complexes cis-[Pd(L)(OAc)2] (1–8) were obtained by the reaction of Pd(OAc)2 with the ligands a–h in a 1:1 mixture of dichloromethane:acetonitrile. The water-soluble phosphine ligands and their palladium complexes were characterized by IR, 1H and 31P NMR. A crystallographic study of complex 1 shows that the Pd(II) ion has a square planar coordination sphere in which the acetate ligands and the diphosphine ligand deviate by less than 0.12 Å from ideal planar. 相似文献