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991.
Ramu Rajasekaran Prakash Rao Aruna Dornadula Koteeswaran Loganathan Padmanabhan Kulandaivel Muthuvelu Ram Rathan Rai Palraj Thamilkumar Chilakapati Murali Krishna Singaravelu Ganesan 《Photochemistry and photobiology》2013,89(2):483-491
Urine is one of the diagnostically important bio fluids, as it has different metabolites in it, where many of them are native fluorophores. Native fluorescence characteristics of human urine samples were studied using excitation–emission matrices (EEMs) over a range of excitation and emission wavelengths, and emission spectra at 405 nm excitation, to discriminate patients with cancer from the normal subjects. The fluorescence spectra of urine samples of cancer patients exhibit considerable spectral differences in both EEMs and emission spectra with respect to normal subjects. Different ratios were calculated using the fluorescence intensity values of the emission spectra and they were used as input variables for a multiple linear discriminant analysis across different groups. The discriminant analysis classifies 94.7% of the original grouped cases and 94.1% of the cross‐validated grouped cases correctly. Based on the fluorescence emission characteristics of urine and statistical analysis, it may be concluded that the fluorophores nicotinamide adenine dinucleotide (NADH) and flavins may be considered as metabolomic markers of cancer. 相似文献
992.
The synthesis of peptides employing Fmoc-amino acid chlorides in presence of HOBt·DCHA salt in solution as well as by the solid-phase methods is described. The coupling was found to be complete in 30 min and free from racemization. The synthesis of β-casomorphin by solid-phase protocol employing Fmoc-amino acid chloride/HOBt·DCHA in DMF–CH2Cl2 has also been outlined. The final peptide was obtained in 80% yield and was fully characterized. 相似文献
993.
Radha Krishna Singamsetty Satish Kumar Vujjini Nagaraju Manne Brahmeshwara Rao Mandava Venkata Naga Vurimidi Himabindu Apurba Battacharya 《合成通讯》2013,43(24):4452-4459
A noninfringing synthesis of simvastatin 1, starting from lovastatin 2, is presented. This synthesis features the protection of the free hydroxyl group of the lovastatin with 3,4-dihydro-2H-pyran (DHP) and opening of the lactone ring with n-BuNH2 to afford amide 4 as a key intermediate. 相似文献
994.
Rhodium(II)-catalyzed reactions of diazo compound and a variety of ethynyl compounds were carried out. These reactions provide a rapid route for preparing a variety of furo[2,3-b]pyran-6-one derivatives in one-pot via cascade reactions of metal carbenoid reaction/ketene formation/[2+2]cycloaddition/ring expansion. 相似文献
995.
A sequential one-pot intermolecular oxy-Michael addition, intermolecular Heck coupling, and intramolecular degradation (retro-oxy-Michael addition) followed by condensation method has been developed for the synthesis of interesting 2-benzoxepin-3(1H)-ones. Significantly, the 2-benzoxepin-3(1H)-ones form the core quantum of biologically vital natural products. The initial oxy-Michael addition and Heck coupling steps involve a straight forward construction of C–O and C–C bonds, whereas, the final condensation step follows a novel mechanistic path via intramolecular degradation, double bond isomerization, and intramolecular condensation. Notably, a remarkable solvent effect has been observed in-order to promote the final intramolecular condensation. 相似文献
996.
M. Kondaiah K. Sreekanth D. Sravana Kumar D. Krishna Rao 《Journal of solution chemistry》2013,42(3):494-515
The densities, ρ, and viscosites, η, of mixtures of propanoic acid with equimolar mixtures of N,N-dimethyl formamide + methanol/ethanol/1-propanol, over the entire composition range of propanoic acid and including the pure liquids, have been measured at the temperatures T/K = 303.15, 313.15, and 323.15. From this experimental data, the excess molar volume, $ V_{\text{m}}^{\text{E}} $ , deviation in viscosity, Δη, and excess Gibbs energy of activation of viscous flow, ΔG *E, have been determined at all three temperatures. The influence of temperature on these mixtures has been studied in terms of molecular interactions. The calculated deviation and excess parameters have been fitted to a Redlich–Kister type polynomial and the corresponding standard deviations were also evaluated. Negative values of $ V_{\text{m}}^{\text{E}} $ and positive values of Δη and ΔG *E are observed at all temperatures over the entire composition range in the mixtures studied. The observed negative and positive values of various excess and deviation parameters are attributed to the existence of strong interactions, like dipole–dipole interactions, H-bonding between the carbonyl group of acid molecules and hydroxyl group of alcohol groups, geometrical fitting of smaller molecules into the voids created by larger molecules in the liquid mixtures. The strength of these interactions in the mixtures was found to decrease with the rise in temperature and increase with an increase of chain length of the alcohols. The derived partial molar volumes and excess partial molar volumes also support the $ V_{\text{m}}^{\text{E}} $ results. The experimental viscosity data of all of these liquid mixtures have been correlated with four viscosity models, those of Grunberg and Nissan, Hind et al., Katti and Chaudhri, and Heric and Brewer. The Katti and Chaudhri model was found to be in good agreement with the experimental values. 相似文献
997.
A kinetic resolution of racemic allyl propargyl alcohols by enantioselective epoxidation is described. 相似文献
998.
Three new α‐phenylcinnamic acid derivatives [4‐methoxy‐α‐phenylcinnamic acid, α‐(4‐methoxyphenyl)‐cinnamic acid, and 4,4′‐bismethoxy‐α‐phenylcinnamic acid] were synthesized, characterized, and selectively used for protecting the exocyclic amino function of purine nucleosides (2′‐deoxyadenosine and 2′‐deoxyguanosine) via active ester generation. The acids were first activated using p‐nitrophenol, and these activated esters were used subsequently for the selective protection of amino groups. The N‐protected derivatives of 2′‐deoxyguanosine and 2′‐deoxyadenosine have been found to be sufficiently stable toward acids, thus minimizing depurination under oligodeoxyribonucleotide synthesis protocol. The ease of syntheses of N‐protected purine nucleosides, their stability under an acidic environment, and mild deprotection conditions are the key advantages of the new protecting groups. 相似文献
999.
Fast and effective ring-closing olefin metathesis (RCM) of diallyamine derivatives of coumarin, quinolone, pyridine, and substituted benzene, using first-generation RCM ruthenium-based catalyst, leads to corresponding pyrrolidine derivatives in 70–95% yields under very mild conditions. 相似文献
1000.
A simple, convenient large‐scale synthesis of a universal solid support useful for the synthesis of oligonucleotides is described. 相似文献