Design,Synthesis, and Anti-Proliferative Activity of Some New Quinoxaline Containing 1,2,4-Thiadiazoles Amide Hybrids

Russian Journal of General Chemistry - A series of new quinoxaline-1,2,4-thiadiazoles amide hybrids has been synthesized and evaluated for their anti-proliferative activity on four different human...     

The Role of the C-3 Substituent in the Asymmetric Dihydroxylation of Hexo-5-Enofuranosides

ABSTRACT

Asymmetric dihydroxylation of vinyl furanosides 1-6 by use of OsO₄, AD-mix-α® and β® is described yielding the corresponding hexofuranose sugars. Vinyl furanosides 2 and 3, with an ester group at C-3, and vinyl manno furanoside 5 on asymmetric dihydroxylation with AD-mix α® exhibited high R diastereoselectivity at C-5. Reversal in diastereoselectivity at C-5 was observed for the 3-deoxy vinyl furanoside 6 giving furanosaccharide 6S with the S configuration at C-5.     

Spectroscopic studies of tantalum doped borate glasses

Glasses with formula 30Li₂O 60B₂O₃xTa₂O₅ (10−x) Bi₂O₃ for x=0, 2, 4, 6 and 8 were prepared via normal melt quenching technique and characterized by refractive index and MDSC. Refractive index (μ) and glass transition temperature (T_g) are found to increase with increase in dopant concentration. Impedance spectra of the samples were recorded in the frequency range 100 Hz–5 MHz in the temperature range 175–275 °C. The plots are typical of those recorded for disordered systems. Conductivities and relaxation times are found to follow Arrhenius type of relation and activation energies are calculated. Optical absorption spectra were recorded in the wavelength range 200–900 nm range from which cutoff wavelength (λ_c) and optical band gap energy (E_g) are evaluated. λ_c is found to decrease while E_g to increase with increase in composition. FTIR spectra of the samples were recorded in the frequency range 400–1500 cm⁻¹ which exhibit characteristic bands corresponding to BO₃, BO₄ stretching vibrations and BO bending vibration. Tightening of the structure is indicated by increase in the vibration of BO₃ at the cost of BO₄ for 8 mol% of Ta₂O₅. This is in support of the highest value of T_g for this sample among the series. Raman spectra of the samples were recorded in the frequency range 200–1200 cm⁻¹. With successive addition of Ta₂O₅, increase in the vibration of Ta–O groups TaO₆ groups to be responsible for observed increase in μ and T_g. An attempt is made to prepare tantalum doped borate glasses and study them by spectroscopic techniques.     

Efficient Synthesis of Hexahydrocarbazoles

Selective reduction of the nitro group in methyl 1-(2-nitrophenyl)-4-oxo-cyclohex-2-enecarboxylates with zinc-acetic acid forms hexahydrocarbazoles. The reaction is applicable to the corresponding pyridyl analogs to generate azahexahydrocarbazoles. This provides an efficient method for the generation of tricyclic framework.

A facile tandem construction of C-O and C-C bonds: a novel one-pot transformation of Baylis-Hillman adducts into 2-benzoxepines

A facile and one-pot synthesis of 2-benzoxepines, from Baylis-Hillman adducts that is, alkyl 3-aryl-3-hydroxy-2-methylenepropanoates, via treatment with HCHO in the presence of concd H₂SO₄, involving tandem construction of C-O and C-C bonds via Prins-type and Friedel-Crafts reactions, is described.     

Unoriented two-stage DEA: The case of the oscillating intermediate products

Data envelopment analysis (DEA) allows us to evaluate the relative efficiency of each of a set of decision-making units (DMUs). However, the methodology does not permit us to identify specific sources of inefficiency because DEA views the DMU as a “black box” that consumes a mix of inputs and produces a mix of outputs. Thus, DEA does not provide a DMU manager with insight regarding the internal source of the organization’s inefficiency.     

Functional Analysis of the Potential Enzymes Involved in Sugar Modulation in High and Low Sugarcane Cultivars

Sugarcane (Saccharum spp.) is a dynamic C4 polyploidy grass used as a major source of sucrose and an alternative for ethanol, food, and energy. Despite growing scientific interest, various sucrose metabolism regulatory aspects have been limited. Biochemical and gene expression studies were conducted on developmental stages, 240–420 days of planting (DAP) in mature leaves of three high and three low sucrose sugarcane cultivars. Sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities were found to be remarkably higher at 240–360 DAP but decrease at 420 DAP. Twofold increases of SS activity was estimated at 240–360 DAP while SPS activity trend was found to be lower than the SS activity. In comparing SS and SPS activities with the brix of respective DAP, results show that these activities are significant and positively correlated with ‘r’ values of 0.69 and 0.68 for SS and SPS, respectively. However, the soluble acid invertase (SAI) and neutral invertase (NI) activities were found to decrease significantly with the maturity of cultivars, negatively correlating with brix at ‘r’ values 0.83 and 0.89 for SAI and NI, respectively. The antioxidant enzyme activity was modulated similar to the invertases activity. Of the six genes, ESAS 11 and 23 associated with sucrose accumulation and ESTS 34 and 41 associated with sugar transport in sugarcane were differentially expressed among the selected high and low sugarcane cultivars. Hence, these findings reinforce the selection of diverse sugarcane cultivars for gene expression studies targeting to quantitative traits and candidate marker determination.     

A general method of obtaining vibrational wavefunctions and Frank-Condon factors at low quantum numbers

A general method of obtaining wavefunctions for empirical diatomic molecular potential functions has been given. Efficacy of the method has been tested by computing Franck-Condon factors for some bands of a new system of SiO using Morse oscillator model and these have been compared with the ones obtained using exact Morse wavefunctions. It is concluded that the method is satisfactory at low quantum numbers.     

The Baylis-Hillman reaction: one-pot facile synthesis of 2,4-functionalized 1,4-pentadienes

The Baylis-Hillman coupling between activated alkenes and alkyl 2-(bromomethyl)prop-2-enoates in the presence of DABCO (or DBU) leading to the formation of 2,4-functionalized 1,4-pentadienes, has been described.     

Oxidation of polythionates with chloramine-T

Summary Chloramine-T has been found to bring about the rupture of S-S link in polythionates in acid medium and oxidise all the sulphur present in the chain into sulphuric acid. Quantitative estimation of a polythionate may be made on the basis of this oxidation reaction.Our thanks are due to Prof. M. R. A. Rao for his interest in the work.