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91.
An efficient [4+2] cyclization of N-methylanilines with maleimides to afford tetrahydroquinolines using N-hydroxyphthalimide as a metal-free and cheap organophotoredox catalyst is reported. The protocol involves C(sp3)H activation of N-methylanilines for the formation of α-amino radical without an oxidant at room temperature. The present method describes an easy preparation of tricyclic heterocycles in good to excellent yields under mild reaction conditions. 相似文献
92.
Two CrIII–picolinato complexes were obtained and characterized in solution. The [Cr(C2O4)(pyac)2]– and [Cr(C2O4)2(pyac)]2– ions (pyac = picolinic acid anion) in acidic solutions undergo a reversible one-end CrIII–picolinato chelate ring opening via CrIII—N bond breaking. The reaction rate was determined spectrophotometrically in the 0.1–1.0 M HClO4 range at I = 1.0 M. The observed pseudo-first order rate constant depends on [H+] according to the equation: k
obs = a + b[H+] + c/[H+]. A reaction mechanism, which assumes participation of the protonated and unprotonated forms of the reactants, has been proposed. The kinetic parameters a, b, c have been defined as a = k
1, b = k
2
Q
1, c = k
–1/Q
2, where k
1, k
–1,k
2 are rate constants for the forward and reverse processes and Q
1, Q
2 are the protolytic equilibrium constants in the term of the proposed mechanism. The activation parameters have been determined and discussed. 相似文献
93.
94.
Prashansa Sharma Suman Pant Shambhavi Rai Renu Bala Yadav Swapnil Sharma Vivek Dave 《应用有机金属化学》2018,32(3)
This research work was proposed to study the antimicrobial activity of the silver nanocoated fabric with the purpose of producing good dressing and clothing material. We synthesized simple, ecofriendly, cost‐effective and sustainable silver nanoparticles by using the aqueous extract of Allium cepa L. Here, A. cepa L. acts as a good reducing and capping agent that produced stable silver nanoparticles having particle size of range 36 ± 1 to 98 ± 2 nm, Poly dispersiblity index 0.234 ± 0.61 to 1.023 ± 0.33 and Zeta potential ‐12 ± 1.5 mV to ‐26 ± 1.2 mV. The effect of temperature and extract volume used was considered for optimization of synthetic procedure. The nanocoated fabric was characterized for morphological study, size (using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE‐SEM) and zeta‐potential (Zeta Potentiometer). The presence of functional groups were observed by using attenuated total reflection‐Fourier transform infrared (ATR‐FTIR) and Raman spectroscopy. The crystallinity and structural property of the synthesized silver nanoparticles were studied in terms of Powder X‐ray diffraction (PXRD). An IC50 value and zone of inhibition was studied which demonstrate that the silver nanocoated fabric have an excellent antibacterial property against Gram‐negative (Escherichia coli) and Gram‐positive (Staphylococcus aureus) bacteria. Further nanocoated fabric material was washed (with function of time 0, 10, 25, and 50 laundry cycles) and still retained their anti‐bacterial activity towards both strain. Initially there was 52 μg/ml of silver nanoparticles on the cotton fabric but after 50 laundry cycle in 500 ml of distilled water the fabric showed 92% efficiency against gram positive and 90% efficacy toward gram negative bacteria. It was found that 4.16 μg/ml nano particles leached in case of S. Aureus and 5.2 μg/mL silver nanoparticles leached in case of E. coli. Nanocoated fabric material synthesized using green synthesis was found to be economical with good resistance to washing. 相似文献
95.
The first attempts to use ethynylsiloxysilsesquioxanes as reagents for hydrosilylation in the presence of Pt‐ and Ru‐based catalysts are reported. The results obtained strongly depend on the catalytic system used. The catalysts are proved to promote regioselective introduction of β‐(E)‐ and α‐fragments of the alkenylsilane group to the silsesquioxane core. The favourable features of these catalytic systems are their high selectivity and the requirement for relatively mild conditions. This methodology was also successfully applied to dihydro‐substituted organosilicon compounds to obtain a new class of silsesquioxane‐based compounds. 相似文献
96.
Gowravaram Sabitha B. V. Subba Reddy J. S. Yadav Nishant Jain B. Jagan Mohan Reddy 《Journal of heterocyclic chemistry》2018,55(4):863-870
A series of new 1,3,4‐oxadiazole‐linked 1,2,3‐triazole/isoxazole derivatives were designed and synthesized. All the synthesized compounds were screened for in vitro anticancer activity against four human cancer cells: HeLa (cervical), MDA‐MB‐231 (breast), DU‐145 (prostate), and HEPG2 (liver). Among 17 compounds tested, 7a , 7c , and 7d showed potent activity toward four cell lines. 相似文献
97.
Srilatha Avuluri Sheshurao Bujaranipalli Saibal Das J.S. Yadav 《Tetrahedron letters》2018,59(39):3547-3549
A first stereoselective total synthesis of 14-memebered β-resorcylic macrolactone 5′-hydroxyzearalenone (1) has been achieved. The key steps are Jocobsen hydrolytic kinetic resolution, Sharpless asymmetric dihydroxylation, Vilsmeier-Haack reaction, Mitsunobu esterification and ring-closing metathesis. 相似文献
98.
99.
Masood Parvez Govindaraji Senthil Veejendra K. Yadav 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):577-579
The stereoisomers of 7‐phenyl‐1‐oxa‐4‐thiaspiro[4.5]decan‐7‐ol, C14H18O2S, have the same stereochemistry at the C atom bearing an OH group, i.e. axial OH and equatorial phenyl groups. However, the acetal S and O atoms are axial and equatorial, respectively, in one isomer and reversed in the second. Furthermore, the crystals of one isomer are composed of hydrogen‐bonded molecules involving the hydroxyl H atom and the O atom of the five‐membered heterocyclic ring, with an O?O distance of 2.962 (3) Å, forming a polymeric chain along the b axis. The asymmetric unit of the other isomer is composed of two molecules, wherein hydroxyl H atoms and the O atoms of the five‐membered heterocyclic rings display intramolecular O—H?O hydrogen bonds with O?O separations of 2.820 (2) and 2.834 (2) Å. 相似文献
100.
Different nanostructures such as flower-like, rod-like, and snowflake-like of ZnO have been synthesized by varying the amount
of agarose using sonochemical method. It is found that morphology is governed by amount of agarose as well as ultrasonic treatment.
Three amounts of agarose 0.01, 0.1, and 1.00 g are used to investigate its effect on ZnO. X-ray diffraction (XRD) confirmed
the formation of single phase with hexagonal structure. Scanning electron microscopy (SEM) showed flower-like, rod-like, and
snowflake-like morphology for 1.00, 0.1, and 0.01 g agarose, respectively. UV/Visible absorption study showed blue shift at
band-edge absorption in comparison to bulk ZnO. Photoluminescence spectra showed band-edge emission at 399 nm for lowest amount
of agarose which quenched on increasing the agarose amount. These findings show a better and more environment friendly procedure
for production of ZnO of readily adjustable morphology. 相似文献