Unusual detritylation of tritylated tetrazole in Sartan molecules

Tritylated tetrazole of 2a underwent unusual detritylation under basic reaction condition during the synthesis of methyl ether of olmesartan medoxomil 1. The unusual detritylation was found to be a common feature in the case of all tetrazole containing Sartan molecules (3-7).     

Propargyl Alcohols as Bifunctional Reagents for Divergent Annulations of Biphenylamines via Dual C−H Functionalization/Dual Oxidative Cyclization

The C−H functionalization strategy provides access to valuable molecules that previously required convoluted synthetic attempts. Dual C−H unsymmetrical functionalization, with a single bifunctional reagent, is an effective tactic. Propargyl alcohols (PAs), despite containing a reactive C≡C bond, have not been explored as building blocks via oxidative cleavage. Annulations via C−H activation are a versatile and synthetically attractive strategy. We disclose PA as a new bifunctional reagent for unsymmetrical dual C−H functionalization of biphenylamine for regioselectively annulated outcomes. On tuning the conditions, the annulation bifurcated towards an unusual dual oxidative cyclization. This method accommodates a wide range of PAs and showcases late-stage diversification of some natural products.     

Biosynthesis of silver nanocrystals by Bacillus licheniformis

The use of microorganisms for the synthesis of nanoparticles is in the limelight of modern nanotechnology. Using the bacterium Bacillus licheniformis, the biosynthesis of silver nanoparticles was investigated. These silver nanoparticles were characterized by means of UV-vis spectroscopy, scanning electron microscopy (SEM), electron diffraction spectroscopy (EDX) and X-ray diffraction (XRD). The nanoparticles exhibited maximum absorbance at 440 nm in UV-vis spectroscopy. The XRD spectrum of silver nanoparticles exhibited 2theta values corresponding to the silver nanocrystal. SEM micrographs revealed the formation of well-dispersed silver nanoparticles of 50 nm, and the presence of silver was confirmed by EDX analysis.     

Multitargeting Prodrugs that Release Oxaliplatin,Doxorubicin and Gemcitabine are Potent Inhibitors of Tumor Growth and Effective Inducers of Immunogenic Cell Death

A multitargeting prodrug ( 2 ) that releases gemcitabine, oxaliplatin, and doxorubicin in their active form in cancer cells is a potent cytotoxic agent with nM IC_50s; it is highly selective to cancer cells with mean selectivity indices to human (136) and murine (320) cancer cells. It effectively induces release of DAMPs (CALR, ATP & HMGB1) in CT26 cells facilitating more efficient phagocytosis by J774 macrophages than the FDA drugs or their co-administration. The viability of CT26 cells co-cultured with J774 macrophages and treated with 2 was reduced by 32 % compared to the non-treated cells, suggesting a synergistic antiproliferative effect between the chemical and immune reactions. 2 inhibited in vivo tumor growth in two murine models (LLC and CT26) better than the FDA drugs or their co-administration with significantly lower body weight loss. Mice inoculated with CT26 cells treated with 2 showed slightly better tumor free survival than doxorubicin.     

Isomer Effect on Energy Storage of π-Extended S-Shaped Double[6]Heterohelicene

Recently, chiral and nonplanar cutouts of graphene have been the favorites due to their unique optical, electronic, and redox properties and high solubility compared with their planar counterparts. Despite the remarkable progress in helicenes, π-extended heterohelicenes have not been widely explored. As an anode in a lithium-ion battery, the racemic mixture of π-extended double heterohelical nanographene containing thienothiophene core exhibited a high lithium storage capability, attaining a specific capacity of 424 mAh g⁻¹ at 0.1 A g⁻¹ with excellent rate capability and superior long-term cycling performance over 6000 cycles with negligible fade. As a first report, the π-extended helicene isomer (PP and MM), with the more interlayer distance that helps faster diffusion of ions, has exhibited a high capacity of 300 mAh g⁻¹ at 2 A g⁻¹ with long-term cycling performance over 1500 cycles compared to the less performing MP and PM isomer and racemic mixture (150 mAh g⁻¹ at 2 A g⁻¹). As supported by single-crystal X-ray analysis, a unique molecular design of nanographenes with a fixed (helical) molecular geometry, avoiding restacking of the layers, renders better performance as an anode in lithium-ion batteries. Interestingly, the recycled nanographene anode material displayed comparable performance.     

Intermolecular Carbophosphination of Alkynes with Phosphole Oxides via Ni−Al Bimetal-Catalyzed C−P Bond Activation

Intermolecular carbophosphination reaction of alkynes or alkenes with unreactive C−P bonds remains an elusive challenge. Herein, we used a Ni−Al bimetallic catalyst to realize an intermolecular carbophosphination reaction of alkynes with 5-membered phosphole oxides, providing a series of 7-membered phosphepines in up to 94 % yield.     

Pd-Catalyzed Arylation and Benzylation of Tyrosine at the δ−C(sp2)−H and C(2) Positions: Expanding the Library of Unnatural Tyrosines

This paper describes Pd(II)-catalyzed picolinamide-directed intermolecular arylation and benzylation of remote δ−C(sp²)−H bond (C(2) position) of the aryl ring in tyrosine derivatives and expansion of the library of unnatural tyrosine. Various racemic and enantiopure bis C(2) (ortho C−H) arylated and benzylated tyrosine derivatives were assembled in good yields. Removal of the picolinoyl moiety after the C(2)−H arylation and assembling of tyrosine-based peptides using C(2)−H arylated tyrosines were shown. Tyrosine derivatives and biaryl amino acids are vital scaffolds in medicinal chemistry. Correspondingly, this work is a contribution towards the expansion of the unnatural tyrosine library with biaryl- or terphenyl and diarylmethane-based tyrosine scaffolds.     

Analysis of thermal,oxidative and cold flow properties of methyl and ethyl esters prepared from soybean and mustard oils

Oilseed crop with high oil content and promising ecological adaptability are potential sources for competitive biodiesel production. This study investigates the scope of utilizing biodiesel development through the methyl and ethyl ester from soybean and mustard oil as an alternative fuel. Methyl and ethyl esters of oils having different fatty acids compositions such as soybean (SOME and SOEE) and mustard oil (MUME and MUEE) were prepared by transesterification with methanol and ethanol in the presence of an alkali-KOH catalyst. The gas chromatographic (GC) analysis of oil samples revealed that primary fatty acid composition in soybean oil was linoleic acid (C_18:2, 51.93%), followed by oleic acid (C_18:1, 22.82%), palmitic acid (C_16:0, 11.56%), linolenic acid (C_18:3, 5.95%) and stearic acid (C_18:0, 4.32%). Whereas, the main components in mustard oil were erucic acid (C_22:1, 32.81%), oleic acid (C_18:1, 24.98%), eicosenoic acid (C_20:1, 10.44%), linolenic acid (C_18:3, 8.61%) and palmitic acid (C_16:0, 2.80%). The physicochemical properties (acid value, iodine value, calorific value, flash point, pour point etc.) of methyl and ethyl ester samples were estimated and found to be within the acceptable range of ASTM D6751 standards specifications. The prepared esters and oil samples were examined for cold flow properties by differential scanning calorimetry (DSC). Results revealed better cold flow properties for MUME (−2.55 °C) and MUEE (−3.10 °C) than SOME (3.21 °C) and SOEE (1.83 °C) due to more unsaturated fatty acid content in MU. Thermal and oxidative stability of samples was determined by thermogravimetric analysis (TG) and differential thermal analysis (DTA). The thermal and oxidative stability ranking of the samples was in the order of oil > methyl esters > ethyl esters.

     

Stationary,completely mixed and symmetric optimal and equilibrium strategies in stochastic games

In this paper, we address various types of two-person stochastic games—both zero-sum and nonzero-sum, discounted and undiscounted. In particular, we address different aspects of stochastic games, namely: (1) When is a two-person stochastic game completely mixed? (2) Can we identify classes of undiscounted zero-sum stochastic games that have stationary optimal strategies? (3) When does a two-person stochastic game possess symmetric optimal/equilibrium strategies? Firstly, we provide some necessary and some sufficient conditions under which certain classes of discounted and undiscounted stochastic games are completely mixed. In particular, we show that, if a discounted zero-sum switching control stochastic game with symmetric payoff matrices has a completely mixed stationary optimal strategy, then the stochastic game is completely mixed if and only if the matrix games restricted to states are all completely mixed. Secondly, we identify certain classes of undiscounted zero-sum stochastic games that have stationary optima under specific conditions for individual payoff matrices and transition probabilities. Thirdly, we provide sufficient conditions for discounted as well as certain classes of undiscounted stochastic games to have symmetric optimal/equilibrium strategies—namely, transitions are symmetric and the payoff matrices of one player are the transpose of those of the other. We also provide a sufficient condition for the stochastic game to have a symmetric pure strategy equilibrium. We also provide examples to show the sharpness of our results.     

Ultrasound-assisted rapid and efficient one-pot synthesis of furanyl spirooxindolo and spiroquinoxalinopyrrolizidines by 1,3-dipolar cycloaddition: a green protocol

Efficient synthesis of novel spirooxindolo and spiroquinoxalinopyrrolizidine derivatives was expediently accomplished with regioselectivity via one-pot, three-component 1,3-dipolar cycloaddition using ultrasonication. Chalcones derived from both heteroaryl methyl ketones and furfural were used as dipolarophiles in these reactions. The synthesized compounds were analyzed by ¹H and ¹³C nuclear magnetic resonance (NMR), mass spectrometry, and elemental (CHN) analysis. Single-crystal X-ray diffraction studies of one of the compounds (11d) proved the structure and regiochemistry of the cycloaddition. The ultrasound methodology is clearly advantageous, and the desired products were obtained in moderate to good yield in shorter reaction time compared with conventional heating and fusion methods.