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101.
Saqib A. Iqbal Jessica Cid Richard J. Procter Marina Uzelac Kang Yuan Michael J. Ingleson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15525-15529
Indoles are privileged heterocycles found in many biologically active pharmaceuticals and natural products. However, the selective functionalization of the benzenoid moiety in indoles in preference to the more reactive pyrrolic unit is a significant challenge. Herein we report that N‐acyl directing groups enable the C7‐selective C?H borylation of indoles using just BBr3. This transformation shows some functional‐group tolerance and notably proceeds with C6 substituted indoles. The directing group can be readily removed in situ and the products isolated as the pinacol boronate esters. Acyl‐directed electrophilic borylation can be extended to carbazoles and anilines with excellent ortho selectivity. 4‐amino‐indoles are amenable to this process, with acyl group installation and directed electrophilic C?H borylation enabling selective formation of C5‐BPin‐indoles. 相似文献
102.
Masood Parvez Kaleem M. Khosa Muhammad Mazhar Saqib Ali Manzar Sohail 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(1):m51-m54
The crystal structures of 3,3‐dimethyl‐3‐(trichlorogermyl)propionic acid, [Ge(C5H9O2)Cl3], 3,3‐dimethyl‐3‐(triphenylgermyl)propionic acid, [Ge(C6H5)3(C5H9O2)], and 3,3‐dimethyl‐3‐(tri‐p‐tolylgermyl)propionic acid, [Ge(C7H7)3(C5H9O2)], have slightly distorted tetrahedral geometries about the Ge atoms. All the structures form dimers via strong O—H·O hydrogen bonds, resulting in eight‐membered rings that can be best described in terms of graph‐set notation (8). 相似文献
103.
Yen-Ting Lin Hafiz Saqib Ali Dr. Sam P. de Visser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(34):8851-8864
The nonheme iron dioxygenase 2-(trimethylammonio)-ethylphosphonate dioxygenase (TmpA) is an enzyme involved in the regio- and chemoselective hydroxylation at the C1-position of the substrate as part of the biosynthesis of glycine betaine in bacteria and carnitine in humans. To understand how the enzyme avoids breaking the weak C2−H bond in favor of C1-hydroxylation, we set up a cluster model of 242 atoms representing the first and second coordination sphere of the metal center and substrate binding pocket, and investigated possible reaction mechanisms of substrate activation by an iron(IV)-oxo species by density functional theory methods. In agreement with experimental product distributions, the calculations predict a favorable C1-hydroxylation pathway. The calculations show that the selectivity is guided through electrostatic perturbations inside the protein from charged residues, external electric fields and electric dipole moments. In particular, charged residues influence and perturb the homolytic bond strength of the C1−H and C2−H bonds of the substrate, and strongly strengthens the C2−H bond in the substrate-bound orientation. 相似文献
104.
Dr. Hafiz Saqib Ali Dr. Sam P. de Visser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(9):e202104167
Taurine/α-ketoglutarate dioxygenase is an important enzyme that takes part in the cysteine catabolism process in the human body and selectively hydroxylates taurine at the C1-position. Recent computational studies showed that in the gas-phase the C2−H bond of taurine is substantially weaker than the C1−H bond, yet no evidence exists of 2-hydroxytaurine products. To this end, a detailed computational study on the selectivity patterns in TauD was performed. The calculations show that the second-coordination sphere and the protonation states of residues play a major role in guiding the enzyme to the right selectivity. Specifically, a single proton on an active site histidine residue can change the regioselectivity of the reaction through its electrostatic perturbations in the active site and effectively changes the C1−H and C2−H bond strengths of taurine. This is further emphasized by many polar and hydrogen bonding interactions of the protein cage in TauD with the substrate and the oxidant that weaken the pro-R C1−H bond and triggers a chemoselective reaction process. The large cluster models reproduce the experimental free energy of activation excellently. 相似文献
105.
Farzana Shaheen Muhammad Sirajuddin Saqib Ali Paul Joseph Dyson Ali Haider Muhammad Nawaz Tahir Khadija Shahid 《Journal of the Iranian Chemical Society》2017,14(2):387-394
A series of tri- and diorganotin(IV) derivatives of 4-(2-thienyl)butyric acid have been synthesized by the reaction of ligand acid with tri- and diorganotin salts in 1:1 and 2:1 molar ratios, respectively. The synthesized compounds have been confirmed by CHNS elemental analyses, FTIR, multinuclear NMR (1H and 13C) spectroscopy and X-ray diffraction studies. NMR data reveal a 5-coordinate geometry for the triorganotin(IV) derivatives, while 6-coordinate for the diorganotin(IV) derivatives, respectively. The X-ray crystallographic analysis of the compound 2 showed polymeric 5-coordinate trigonal bipyramidal geometry. Antimicrobial studies were also evaluated against different strains of bacteria (Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis and Staphylococcus aureus) and fungi (Mucor species, Aspergillus solani, Helminthosporium oryzae, Aspergillus flavus, Aspergillus niger) to establish the biological significance of these compounds. The synthesized compounds probably work by interfering with the ability of bacteria to form cell walls by keeping unwanted substances from entering their cells and stop the contents of their cells from leaking out due which the bacteria get die. The antifungal activity of some of the tested compound is comparable to that of the standard drug, terbinafine. From their antimicrobial results, it was concluded that they might be used as potential candidate for the generation of new antimicrobial drugs. 相似文献
106.
Mukhtiar Hussain Zia‐ur‐Rehman Muhammad Hanif Muhammad Altaf Aziz‐ur‐Rehman Saqib Ali Kingsley J. Cavell 《应用有机金属化学》2011,25(6):412-419
A series of new diethyltin(IV) derivatives of substituted phenyl acrylates have been synthesized and characterized by elemental analysis, IR, multinuclear NMR (1H, 13C, 19F and 119Sn) and X‐ray single crystal analysis. X‐ray single crystal diffraction study of complex 8 has shown the formation of secondary O···Sn, F···H and H···O intermolecular interactions. These complexes proved to be good antitumor agents. The antitumor properties are presumably due to the intercalative mode of interaction of these complexes with the tumor cells' DNA. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
107.
Sadiq‐ur‐Rehman Saqib Ali Masood Parvez M. Mazhar Amin Badshah 《Heteroatom Chemistry》2004,15(5):398-406
The ligand, 3‐(3‐fluorophenyl)‐2‐phenylpropenoic acid, [C15H11FO2] ( I ) was prepared by reacting equimolar amount of phenyl acetic acid with 3‐fluorobenzaldehyde (1:1) using Perkin condensation method. The trimethyltin(IV) carboxylate, [Me3SnO2FH10C15] ( II ) was synthesized by refluxing an equimolar (1:1) mixture of trimethyltin chloride and silver salt of the ligand acid, [C15H10FO2Ag] ( Ia ). The ligand and complex both were characterized by elemental analysis, IR, mass, 1H NMR, and X‐ray crystallographic data. On the basis of 1H NMR data, (2J[117/119Sn, 1H] and C Sn C bond angle), it is concluded that the environment around the tin atom in solution is tetrahedral. The Infrared spectroscopic results showed that trimethyltin(IV) derivative has 5‐coordinated polymeric structure with bridging carboxylate groups in the solid state, which has been confirmed by the X‐ray crystallographic data. The crystal of ligand acid ( I ) is triclinic with space group Pbar1. However, the crystal of the complex ( II ) is monoclinic with space group C2/c. The geometry around the tin atom is distorted trigonal bipyramid with O(1) and O(2) atoms in apical positions. The ligand ( I ) and complex ( II ) were also tested for their biocidal activities. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:398–406, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20032 相似文献
108.
Niaz Muhammad Afzal Shah Zia-ur-Rehman Shaukat Shuja Saqib Ali Rumana Qureshi Auke Meetsma Muhammad Nawaz Tahir 《Journal of organometallic chemistry》2009,694(21):3431-3437
Four new organotin(IV) carboxylates, [Bu2SnL2] (1), [Et2SnL2] (2), [Bu3SnL]n (3), [Me3SnL]n (4), where L = 4-nitrophenylethanoates, were synthesized and characterized by elemental analysis, FT-IR and multinuclear NMR (1H and 13C). Spectroscopic results authenticated the coordination of ligand to the organotin moiety via COO group while X-ray single crystal analysis revealed bidentate chelating mode of coordination of ligand in complex 2 and a bridging behavior in complexes 3 and 4. Cyclic voltammetric (CV) technique was used to evaluate the electrochemical, kinetic and thermodynamic parameters of complexes 1-4, interacting with DNA. The linearity of the plots between the peak current (I) and the square root of the scan rate (ν1/2) indicated the electrochemical processes to be diffusion controlled. The diffusion coefficients of the free (Df) and DNA bound forms (Db), standard rate constants (ks) and charge transfer coefficients (α) were determined by the application of Randle–Sevcik, Nicholson and Kochi equations. Furthermore, the binding constants evaluated from voltammetric data revealed the following increasing order of binding strength: 2 < 1 < 4 < 3. For 1 and 2, the activity against prostate cancer cell lines (PC-3) was found consistent with the order obtained from voltammetric behavior. 相似文献
109.
Masood Parvez Saqib Ali Sajjad Ahmad Moazzam Hussain Bhatti Muhammad Mazhar 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):m334-m335
The crystal structure of catena‐poly[[tri‐n‐butyltin]‐μ‐3‐(1‐naphthylaminocarbonyl)acrylato‐κ2O1:O3], [Sn(C4H9)3(C14H10NO3)]n, is composed of polymeric chains wherein the metal center exhibits a distorted trigonal‐bipyramidal geometry, with three n‐butyl groups defining the trigonal plane [mean Sn—C 2.133 (7) Å] and the axial positions being occupied by the carboxylate O atoms of two different N‐(1‐naphthyl)maleamate ligands with inequivalent Sn—O distances [2.167 (4) and 2.457 (4) Å]. The N‐(1‐naphthyl)maleamate fragment forms an essentially planar seven‐membered ring involving an intramolecular N—H?O hydrogen bond. 相似文献
110.