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81.
82.
Markad SD Karanjule NS Sharma T Sabharwal SG Puranik VG Dhavale DD 《Organic & biomolecular chemistry》2006,4(13):2549-2555
The Johnson-Claisen rearrangement of D-glucose-derived allylic alcohols 5a,b, afforded sugar-substituted gamma,delta-unsaturated ester in high yield. Conversion of the ester group to an azidomethyl group, epoxidation of the double bond and hydrogenation gave pyrrolidine ring skeletons 13a and 13b, which were transformed to tetrahydroxy perhydroaza-azulenes 1a and 1b, respectively. Glycosidase inhibitory activity was also evaluated. 相似文献
83.
Vrushali H. Jadhav Omprakash P. Bande Vedavati G. Puranik Dilip D. Dhavale 《Tetrahedron: Asymmetry》2010,21(2):163-170
The Sharpless asymmetric epoxidation of d-glucose-derived allyl alcohol 4 afforded α- and β-epoxides 5a and 5b in high stereoselectivity. The epoxide ring opening in 5a/5b was studied with different nucleophilic azido reagents, under various reaction conditions, and was found to be highly regioselective to give the preferential formation of 6-azido diol 6a/6b over 5-azido-diol 7a/7b. The 6-azido diol 6a/6b and 5-azido diol 7a/7b thus obtained were converted to the corresponding seven- and six-membered iminosugar, namely, azepane 1a/1b and 1-deoxy-nojirimycin 2a/2b. 相似文献
84.
This paper describes the experimental circuit and measured performance of varactor tuned Gunn oscillator at W-band. The power output of 12.5 dBm has been achieved when packaged GaAs Gunn diode is used. Linear frequency excursion of 150 MHz with power variation of 1 dB has been observed when varactor was given reverse bias from 0 to 20 volts. GaAs hyperabrupt varactor is used in parallel to gunn diode at a distance of odd multiple of g/2 in waveguide channel. 相似文献
85.
A one-pot synthesis of 6-mercaptopurines from 4,5-diamino-6-chloro-pyrimidine, an aldehyde and elemental sulfur is presented. The key advantage of this procedure is that it utilizes the in situ generated H2S to convert the chloro to a mercapto group. 相似文献
86.
Dhavale DD Markad SD Karanjule NS PrakashaReddy J 《The Journal of organic chemistry》2004,69(14):4760-4766
The asymmetric dihydroxylation of a d-glucose derived alpha,beta-unsaturated ester 3 afforded syn vicinal diols in good to high diastereoselectivity. The conversion of these vicinal diols to the corresponding cyclic sulfate, regio-, stereoselective nucleophilic ring opening by sodium azide, and LAH reduction afforded amino heptitols 7a,b that were converted to azepane 1c,d and nojirimycin analogues 2c,d. 相似文献
87.
Precise conductance measurements of solutions of lithium chloride, lithium bromide, lithium iodide, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, tetrabutylammonium bromide, and tetrabutylammonium tetraphenylborate in N,N-dimethylacetamide are reported at 25°C in the concentration range 0.005–0.015 mol-dm–3. The conductance data have been analyzed by the 1978 Fuoss conductance equation in terms of the limiting molar conductance (0), the association constant (K
a), and the association diameter (R). The limiting ionic conductances have been estimated from an appropriate division of the limiting molar conductivity of the reference electrolyte Bu4NBPh4. Slight ionic association was found for all these salts in this solvent medium. The results further indicate significant solvation of Li+ion, while the other ions are found to be unsolvated in N,N-dimethylacetamide. 相似文献
88.
Precise conductance measurements have been performed for lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, sodium perchlorate, and sodium tetraphenylborate in 2-methoxyethanol–water mixtures at four different mole fractions, i.e., 0.056, 0.136, 0.262, and 0.486 of 2-methoxyethanol (69.73 D 26.55) at 25°C in the concentration range 0.0004–0.0642 mol-dm–3. The limiting molar conductivity °, the association constant K
A, and the association distance R for the solvent mixtures have been evaluated from the conductance concentration data using the 1978 Fuoss conductance equation. The single-ion conductances have been estimated using the reference electrolyte tetrabutylam-monium tetraphynylborate(Bu4NBPh4). The analysis of the data indicates that for most salts ion association is appreciable in the solvent mixtures with a mole fraction of the cosolvent of 0.262 or higher. The results have been interpreted in terms of ion-solvent interactions and structural changes in the mixed solvent media. 相似文献
89.
M.M. Kanitkar V.N. Shukla P.L. Kanitkar Dilip S. Joag 《Solid State Communications》1984,50(9):817-819
Metallic glass Fe40Ni40B20 is imaged at liquid hydrogen temperature in field ion microscope. Pair and angular distributions are obtained from the analysis of a large number of micrographs. The pair distribution is found to exhibit features typical of metallic glasses. The angular distribution agrees well with the theoretical distribution for Lennard-Jones glass obtained by Jacobaeus et al. The closer agreement achieved has been attributed to the better experimental conditions and the improved resolution of field ion microscope. 相似文献
90.
Wonsook Ha Robert S. Mansell Dilip Shinde Nam-Ho Kim Husein A. Ajwa Craig D. Stanley 《Transport in Porous Media》2009,78(1):77-99
Pre-plant application of toxic fumigants to soil beds covered by plastic film is commonly used in agriculture to control soil-borne
pathogens. Plastic mulch covers tend to physically suppress the emissive loss of gaseous fumigant to the atmosphere. When
liquid fumigant metham sodium (MS) is applied in irrigation water to field soil, it is rapidly transformed to the gaseous
methyl isothiocyanate (MITC). The gaseous MITC is a potential atmospheric contaminant, and any untransformed MS is a potential
contaminant of underlying groundwater due to the high water solubility of MS. A finite element numerical model was developed
to investigate two-dimensional MITC fate/transport under non-isothermal soil conditions. Directional solar heating on soil
beds, coupled heat and water flow in the soil, and non-isothermal chemical transport were included in the model. Field soil
data for MITC distribution, soil water content, meteorological data, and laboratory data were used to verify the model for
soil beds covered with plastic mulch. Four possible scenarios were considered: low and high drip-irrigation rates and low
and high water contents. The movement of the center of MITC mass in the soil profile was effectively simulated. The lower
drip-irrigation rate of MS yielded more extensive coverage of MITC in the plastic-covered soil bed. The lower soil air contents
due to higher soil water contents for the higher irrigation rate resulted in high concentrations of soil MITC. NRMSE (normalized
root mean square error) calculations further verified that the model predicted fumigant fate/transport well under these non-isothermal
field conditions. 相似文献