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91.
An array of 2-substituted-4,5-diphenyloxazoles were found to be cleaved to triacylamines and diacylamines (imides) using a reagent system composed of m-chloroperbenzoic acid (MCPBA) and 2,2′-bipyridinium chlorochromate (BPCC). The 2-alkyl-4,5-diphenyloxazoles give imides (38–60%) as the predominant cleavage product while the 2-aryl-4,5-diphenyloxazoles give triacylamines (44–71%). Two mechanisms involving intermediates such as cyclic endoperoxides or oxachromacycles were proposed. An application of the oxidative cleavage to the multi-step synthesis of (±)-phoracantholide I seco acid is detailed. 相似文献
92.
Siddappa Patil Karolin Dietrich Anthony Deally Brendan Gleeson Helge Müller‐Bunz Francesca Paradisi Matthias Tacke 《Helvetica chimica acta》2010,93(12):2347-2364
From the reaction of 1H‐imidazole ( 1a ), 4,5‐dichloro‐1H‐imidazole ( 1b ), 1H‐benzimidazole ( 1c ), 1‐methyl‐1H‐imidazole ( 1d ), and 1‐methyl‐1H‐benzimidazole ( 1f ) with methyl 4‐(bromomethyl)benzoate ( 2 ), symmetrically and nonsymmetrically 4‐(methoxycarbonyl)benzyl‐substituted N‐heterocyclic carbene (NHC) precursors, 3a – 3f , were synthesized. These NHC precursors were then reacted with silver(I) acetate (AgOAc) to yield the NHC–silver acetate complexes (acetato‐κO){1,3‐bis[4‐(methoxycarbonyl)benzyl]imidazol‐2‐ylidene}silver ( 4a ), (acetato‐κO){4,5‐dichloro‐1,3‐bis[4‐(methoxycarbonyl)benzyl]‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4b ), (acetato‐κO){1,3‐bis[4‐(methoxycarbonyl)benzyl]‐2,3‐dihydro‐1H‐benzimidazol‐2‐yl}silver ( 4c ), (acetato‐κO){1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4d ), (acetato‐κO){4,5‐dichloro‐1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4e ), and (acetato‐κO){1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐benzimidazol‐2‐yl}silver ( 4f ), respectively. The three NHC–AgOAc complexes 4a, 4c , and 4d were characterized by single‐crystal X‐ray diffraction. All compounds studied in this work were preliminarily screened for their antimicrobial activities in vitro against Gram‐positive bacteria Staphylococcus aureus, and Gram‐negative bacteria Escherichia coli using the qualitative disk‐diffusion method. All NHC–AgOAc complexes exhibited weak‐to‐medium antibacterial activity with areas of clearance ranging from 4 to 7 mm at the highest amount used, while the NHC precursors showed significantly lower activity. In addition, NHC–AgOAc complexes 4a and 4b , and 4d – 4f exhibited in preliminary cytotoxicity tests on the human renal‐cancer cell line Caki‐1 medium‐to‐high cytotoxicities with IC50 values ranging from 3.3±0.4 to 68.3±1 μM . 相似文献
93.
Rajendra D. Patil Girdhar Joshi Subbarayappa Adimurthy 《Monatshefte für Chemie / Chemical Monthly》2010,141(4):1093-1099
Abstract
Hydroarylation of styrenes with arenes/heteroarenes using KHSO4 (10 mol%) as an efficient heterogeneous catalyst is described. High conversion and selectivity (>99%) were observed for hydroarylation of styrenes with 2-naphthol at reflux temperature of 1,2-dichloroethane. Yields were quantitative with all styrenes. Moderate to good conversions and selectivities were achieved with other aromatics and heteroaromatics under the same conditions. Regeneration and reusability of KHSO4 were demonstrated. Addition of a trace amount of water could help to reactivate the KHSO4 through dispersion and to facilitate the hydroarylation reaction. 相似文献94.
Toche RB Janrao RA Bagul SM Patil SP Pagar BP Nikam PS 《Journal of fluorescence》2011,21(4):1617-1624
Suzuki-Miyaura cross coupling was successfully used for C5-arylation in 4-amino-2-chloroquinoline-3-carbaldehyde using arylbornic acid and tetrakistriphenylphosphine palladium catalyst in water. Friedländer condensation reaction on 4-amino-2-chloro/2-arylquinoline-3-carbaldehyde and aromatic ketones gave novel aryl and diarylbenzo[h] [1, 6]naphthyridines in good yields. Fluorescence quantum yields were increased by introducing C2 and C5 π donor aryl benzo[h][1, 6]naphthyridines derivatives. 相似文献
95.
A.J. ChoudhuryS.A. Barve Joyanti Chutia A.R. PalR. Kishore JagannathM. Pande D.S. Patil 《Applied Surface Science》2011,257(20):8469-8477
Hexamethyldisiloxane (HMDSO) films have been deposited on bell metal using radiofrequency plasma assisted chemical vapor deposition (RF-PACVD) technique. The protective performances of the HMDSO films and their water repellency have been investigated as a function of DC self-bias voltage on the substrates during deposition. Plasma potential measurements during film deposition process are carried out by self-compensated emissive probe. Optical emission spectroscopy (OES) analyses of the plasma during deposition reveal no significant change in the plasma composition within the DC self-bias voltage range of −40 V to −160 V that is used. Raman and X-ray photoelectron spectroscopy (XPS) studies are carried out for film chemistry analysis and indicate that the impinging ion energy on the substrates influences the physio-chemical properties of the HMDSO films. At critical ion energy of 113 qV (corresponding to DC self-bias voltage of −100 V), the deposited HMDSO film exhibits least defective Si-O-Si chemical structure and highest inorganic character and this contributes to its best corrosion resistance behavior. The hardness and elastic modulus of the films are found to be bias dependent and are 1.27 GPa and 5.36 GPa for films deposited at −100 V. The critical load for delamination is also bias dependent and is 11 mN for this film. The water repellency of the HMDSO films is observed to be dependent on the variation in surface roughness. The results of the investigations suggest that HMDSO films deposited by RF-PACVD can be used as protective coatings on bell metal surfaces. 相似文献
96.
Premanand Ramrao Patil 《Journal of carbohydrate chemistry》2013,32(5):279-293
Dry ball milling of hexosides with trityl chloride in the presence of DABCO or Na2CO3 has been found to result in their complete conversion to the respective 6‐O‐trityl ethers. Further wet grinding of the reaction mixture with Ac2O in the presence of DMAP led to the respective fully protected hexosides in good to excellent yields after isolation. It has been found to be an effective one‐pot two‐step synthesis under solvent‐free condition. The speed of homogenization has been shown to highly influence the rate and outcome of the reaction, and commercially available planetary ball mill has been proved to be very convenient for carrying out the reaction under standardized and reproducible conditions. 相似文献
97.
98.
P. M. Kadam N. L. Tarwal P. S. Shinde R. S. Patil H. P. Deshmukh P. S. Patil 《Applied Physics A: Materials Science & Processing》2009,97(2):323-330
Suitable host lattice and morphology for easy intercalation and deintercalation process are crucial requirements for electrochromic
device. In this investigation, the evolution of structural and morphological changes and their effect on electrochromic (EC)
properties of spray-deposited WO3 thin films are studied. Films of different morphologies were deposited from an ammonium tungstate precursor solution using
a novel pulsed spray pyrolysis technique (PSPT) on tin-doped indium oxide (ITO) coated glass substrates by varying quantity
of spraying solution. Interesting morphological transition from beads-to-wires-to-fibers as a function of quantity of sprayed
solution has been demonstrated. The porosity, crystallinity and “open” structures in the films consisting of beads, wires,
and fiber-like morphology enabled us to correlate these aspects to their EC performance. WO3 films comprising wire-like morphology (20 cc spraying quantity) exhibited better EC properties both in terms of coloration
efficiency (42.7 cm2/C) and electrochemical stability (103 colored/bleached cycles) owing to their adequate open structure, porosity, and amorphicity, compared with the films having
bead/fiber-like morphology. 相似文献
99.
In this paper, an algorithm for chemical non‐equilibrium hypersonic flow is developed based on the concept of energy relaxation method (ERM). The new system of equations obtained are studied using finite volume method with Harten–Lax–van Leer scheme for contact (HLLC). The original HLLC method is modified here to account for additional species and split energy equations. Higher order spatial accuracy is achieved using MUSCL reconstruction of the flow variables with van Albada limiter. The thermal equilibrium is considered for the analysis and the species data are generated using polynomial correlations. The single temperature model of Dunn and Kang is used for chemical relaxation. The computed results for a flow field over a hemispherical cylinder at Mach number of 16.34 obtained using the present solver are found to be promising and computationally (25%) more efficient. The present solver captures physically correct solution as the entropy conditions are satisfied automatically during the computations. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
100.
Abhijit Patil 《Optics Communications》2006,257(1):120-132
This paper proposes a subspace parameter estimation method which besides allowing for accommodating multiple PZTs in an optical interferometer permits for extracting in real time values of phase shifts between data frames at each pixel point. The technique enables to freely choose values of phase shifts between 0 and π. A generalized phase measurement algorithm allows for computing multiple phase information present in the interferometer. The method facilitates the use of spherical beams, addresses errors arising from the miscalibration of the phase shifting devices, and is capable of handling nonsinusoidal waveforms in an effective manner. Numerical simulations demonstrate that phase distributions can be measured with high accuracy even in the presence of noise. 相似文献