01867nas a2200241 4500008004100000022001400041245012500055210006900180260009900249300001000348490000800358520098600366653001801352653000801370653001301378653001401391653001201405653001301417100002301430700001701453700002701470856012801497 2012 eng d a0008-621500aRadical mediated deoxygenation of inositol benzylidene acetals: conformational analysis, DFT calculations, and mechanism0 aRadical mediated deoxygenation of inositol benzylidene acetals c aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcAPR a26-340 v3513 a

Xanthates of 1,3-benzylidene acetal derivatives of myo- and neo-inositols undergo dideoxygenation under Barton-McCombie conditions, as a result of intramolecular abstraction of the benzylidene acetal hydrogen and subsequent cleavage of the acetal ring. Scrutiny of structure of these bicyclic inositol derivatives shows that although the conformation of the two rings can vary depending on the configuration of the inositol ring and the phase in which the molecules are present, both the xanthates lead to the formation of the same dideoxyinositol. DFT calculations on these molecular systems suggest that neo-inositol derivatives undergo conformational change prior to radical formation while myo- inositol derivatives undergo conformational change subsequent to radical formation, during the deoxygenation reaction. A low barrier for intramolecular hydrogen transfer supports the extreme facility of this deoxygenation reaction. (C) 2012 Elsevier Ltd. All rights reserved.

10aDeoxygenation10aDFT10aInositol10aMechanism10aRadical10aXanthate1 aGurale, Bharat, P.1 aVanka, Kumar1 aShashidhar, Mysore, S. uhttp://library.ncl.res.in/content/radical-mediated-deoxygenation-inositol-benzylidene-acetals-conformational-analysis-dft-002131nas a2200265 4500008004100000022001400041245014200055210006900197260009700266300001200363490000600375520116200381653000901543653001301552653001301565653002501578653001401603653001801617100001901635700001801654700002101672700002601693700001901719856012701738 2015 eng d a2210-803300aLannea coromandelica attenuates glucagon and oxyntomodulin mediated cAMP formation in HEK cells stably-expressing human glucagon receptor0 aLannea coromandelica attenuates glucagon and oxyntomodulin media aOFFICE JENA, P O BOX 100537, 07705 JENA, GERMANYbELSEVIER GMBH, URBAN & FISCHER VERLAGcSEP a153-1570 v53 a

Antagonism of glucagon is a potential therapeutic approach for Type 2 diabetes mellitus (T2DM). The bark extract of Lannea coromandelica has been reported to have hypoglycemic or anti-diabetic effects on animal models and human subjects. The aim of this study was to elucidate the molecular mechanisms of L. coromandelica extract as a glucagon receptor antagonist. The aqueous extract of L. coromandelica bark attenuated glucagon-mediated cAMP formation in a concentration dependent manner with an IC50 value of 4.24 +/- 1.31 mu g/ml. It shifted a concentration response curve of glucagon towards the right with a 4, 21 and 40-fold change in IC50 at 6.25, 12.5 and 25 mu g/ml of extract, respectively. Additionally, it attenuated an oxyntomodulin-mediated cAMP response. The extract was found specifically to inhibit glucagon mediated cAMP formation since it was ineffective in reducing cAMP levels nonspecifically-elevated by forskolin. The data support that the aqueous extract of L. coromandelica antagonizes the glucagon receptor and has the potential to reduce glucagon mediated liver glucose output. (C) 2015 Elsevier GmbH. All rights reserved.

10acAMP10aDiabetes10aGlucagon10aLannea coromandelica10aMechanism10aOxyntomodulin1 aWalunj, Sameer1 aGupta, Rajesh1 aJoshi, Swati, P.1 aSabharwal, Sushma, G.1 aJoshi, Kalpana uhttp://library.ncl.res.in/content/lannea-coromandelica-attenuates-glucagon-and-oxyntomodulin-mediated-camp-formation-hek-002259nas a2200241 4500008004100000022001400041245016300055210006900218260000800287300001600295490000700311520140300318653001901721653001401740653001601754653002601770653001301796653001401809100002601823700002801849700002101877856011901898 2016 eng d a1944-399400aMechanistic and spectroscopic investigations of Ru3+-catalyzed oxidative degradation of azidothymidine by heptavalent manganese at environmentally relevant pH0 aMechanistic and spectroscopic investigations of Ru3catalyzed oxi cDEC a28349-283620 v573 a

The rapid increase in the population across the world has increased the consumption of pharmaceutical substances. These pharmaceutical substances have penetrated into the water through various ways. Mechanistic and spectroscopic investigations of Ru3+-catalyzed oxidative degradation of azidothymidine (AZT) by heptavalent manganese was studied for the first time. The values of pH-dependent apparent second-order rate constant show that Ru3+ accelerates the rate of the oxidative degradation of AZT by heptavalent manganese eight times faster than uncatalyzed reaction. Ru3+ catalytic oxidative degradation of AZT by heptavalent manganese was greatly depending on the pH. The removal of the AZT by heptavalent manganese in the presence of Ru3+ shows unit order with respect to heptavalent manganese, Ru3+, and AZT. The influences of dielectric constant, ionic strength, pH, addition of monomer, variation in catalyst concentration, etc. on the rate of the reaction were studied thoroughly and discussed in detail. The eight different products produced during the reaction were analyzed using the high-resolution mass spectrometry. Activation parameters were determined from variation in temperature during the reaction. The catalytic plausible mechanism was projected in which Ru3+ is oxidized to higher oxidation states of ruthenium by heptavalent manganese at environmentally relevant pH.

10aAzidothymidine10acatalysis10aDegradation10aHeptavalent manganese10akinetics10aMechanism1 aKulkarni, Raviraj, M.1 aBhamare, Vijaykumar, S.1 aSanthakumari, B. uhttp://library.ncl.res.in/content/mechanistic-and-spectroscopic-investigations-ru3-catalyzed-oxidative-degradation01921nas a2200229 4500008004100000022001400041245013600055210006900191260000800260300001600268490000700284520112000291653001601411653001301427653001401440653001701454653001501471100002601486700002801512700002101540856013001561 2016 eng d a1944-399400aOxidative transformation of antiretroviral drug zidovudine during water treatment with permanganate: reaction kinetics and pathways0 aOxidative transformation of antiretroviral drug zidovudine durin cFEB a24999-250100 v573 a

The presence of the pharmaceutical substances in the water has been reported by many studies and has attracted attention across the world. The mechanistic insight into oxidation of antiretroviral drug zidovudine (ZDV) by potassium permanganate was investigated between the pH values 3.0 and 9.0. The pH-dependent second-order rate constants were determined and rate constants decreased with an increase in pH. The products of the reaction were identified by high-resolution mass spectrometry. A probable mechanism is proposed which involves the formation of an intermediate complex between permanganate and ZDV, which further undergoes degradation in subsequent fast steps to form various oxidized products. The different parameters like effect of initially added products, solvent polarity, ionic strength, temperature, and pH on the rate of the oxidative degradation of ZDV by permanganate were systematically studied. The various activation parameters were determined from the effect of variation in temperature on the oxidative degradation of ZDV by permanganate in acidic medium and discussed in detail.

10aDegradation10akinetics10aMechanism10aPermanganate10aZidovudine1 aKulkarni, Raviraj, M.1 aBhamare, Vijaykumar, S.1 aSanthakumari, B. uhttp://library.ncl.res.in/content/oxidative-transformation-antiretroviral-drug-zidovudine-during-water-treatment-permanganate02394nas a2200241 4500008004100000022001400041245009700055210006900152260000900221300001400230490000600244520158800250653001901838653002401857653001401881653003001895653002101925100002401946700001601970700001501986700002402001856012702025 2019 eng d a2196-021600aMedium modulated oxygen reduction activity of Fe/Co active centre-engrafted electrocatalysts0 aMedium modulated oxygen reduction activity of FeCo active centre cJUN  a2956-29640 v63 a

Iron and cobalt metal atoms are effective active centers for the synthesis of carbon-based noble-metal-free catalysts for the oxygen reduction reaction (ORR) owing to their cost-effective intrinsic activity and tunable properties. Annealing of the active center with the conducting carbon enhances the ORR activity significantly. Herein, we have engrafted Fe and Co active centers in the homemade conducting carbon and the ORR performance has been closely observed under acidic and basic pH conditions to understand the influence of the medium and participating moieties towards the performance. In the half-cell reaction, the onset potential and half-wave potential for ORR are governed by the surface intermediates and concomitantly driven by the adsorption energies of the intermediates over the active centers. The iron and cobalt active center-engrafted carbon catalyst behaves differently in acidic and basic electrolytes owing to the dissociation of the surface intermediates. The iron-based catalyst shows improved onset potential against the cobalt-based one. Similarly, the cobalt-based catalyst shows improved half-wave potential against the iron active-center-grafted catalyst. The combined synergistic effect of the two catalysts is realized in the composition represented as Fe/2Co-N-GVC, where improved onset and half-wave potentials are noted in basic medium. A significant variation in the activity of the catalyst is observed as the medium changes from acidic to basic and the effect is directly associated with the surface adsorption of the intermediates.

10aactive centers10ahalf-wave potential10aMechanism10aoxygen reduction reaction10atransition state1 aKashyap, Varchaswal1 aAnand, Aljo1 aSoni, Roby1 aSreekumar, Kurungot uhttp://library.ncl.res.in/content/medium-modulated-oxygen-reduction-activity-feco-active-centre-engrafted-electrocatalysts01868nas a2200241 4500008004100000022001400041245013600055210006900191260000800260300001200268490000600280520105500286653001701341653001901358653001201377653001401389653001101403653002901414100002201443700001801465700002001483856012301503 2019 eng d a2155-543500aNickel-catalyzed straightforward and regioselective C-H alkenylation of indoles with alkenyl bromides: scope and mechanistic aspect0 aNickelcatalyzed straightforward and regioselective CH alkenylati cJAN a431-4410 v93 a

Nickel-catalyzed regioselective C-H bond alkenylation of indoles and related heteroarenes with alkenyl bromides is accomplished under relatively mild conditions. This method allows the straightforward synthesis of C-2 alkenylated indoles employing an air-stable and well-defined nickel catalyst, (bpy)NiBr2, providing a solution to the limitations associated with hydroindolation and oxidative alkenylation. The reaction conceded the coupling of indole derivatives with various alkenyl bromides, such as aromatic and heteroaromatics, alpha- and beta-substituted as well as exo- and endo-cyclic alkenyl compounds. An extensive mechanistic investigation, including controlled study, reactivity experiments, kinetics and labeling studies, and EPR and XPS analyses, highlights that the alkenylation proceeds through a single-electron transfer process comprising an odd-electron oxidative addition of alkenyl bromide. Furthermore, the alkenylation operates via a probable Ni(I)/Ni(III) pathway involving the rate-limiting C-H nickelation of indole.

10aalkenylation10aC-H activation10aindoles10aMechanism10aNickel10asingle-electron transfer1 aJagtap, Rahul, A.1 aVinod, C., P.1 aPunji, Benudhar uhttp://library.ncl.res.in/content/nickel-catalyzed-straightforward-and-regioselective-c-h-alkenylation-indoles-alkenyl01870nas a2200289 4500008004100000022001400041245013600055210006900191260000900260300001600269490000700285520090000292653001901192653001901211653002001230653001201250653001401262653001101276653002301287100002801310700002901338700001801367700002401385700002601409700002001435856012501455 2021 eng d a2155-543500aNi(II)-catalyzed intramolecular C-H/C-H oxidative coupling: an efficient route to functionalized cycloindolones and indenoindolones0 aNiIIcatalyzed intramolecular CHCH oxidative coupling an efficien cOCT  a12384-123930 v113 aNickel(II)-catalyzed intramolecular C(sp(2))-H/C(sp(3))-H and C(sp(2))-H/C(sp(2))-H oxidative couplings in indoles are achieved via chelation assistance. These reactions provide access to biologically relevant five- and six-membered substituted cyclopentaindolones, carbazolones, and indenoindolones in high yields and good chemoselectivity employing an air-stable and defined nickel catalyst, (bpy)Ni(OAc)(2). The oxidative cyclizations proceeded either through a six-membered or an unconventional seven-membered nickelacycle. An extensive mechanistic investigation by experiments and theoretical calculations revealed a facile indole's C(2)-H nickelation and a rate-limiting reductive elimination process. This intramolecular oxidative cyclization operates via a probable Ni(II)/Ni(III) pathway involving single-electron oxidation of nickel without the participation of a carbon-based radical.10aC-H activation10acycloindolones10aindenoindolones10aindoles10aMechanism10aNickel10aoxidative coupling1 aAnkade, Shidheshwar, B.1 aSamal, Pragnya, Paramita1 aSoni, Vineeta1 aGonnade, Rajesh, G.1 aKrishnamurty, Sailaja1 aPunji, Benudhar uhttp://library.ncl.res.in/content/niii-catalyzed-intramolecular-c-hc-h-oxidative-coupling-efficient-route-functionalized01751nas a2200253 4500008004100000022001400041245009500055210006900150260000800219300001500227490000700242520095900249653001901208653001701227653000901244653001101253653001401264653001401278100002201292700002201314700002401336700002001360856011701380 2022 eng d a1861-472800aEfficient route to 3,3 `-biindolinylidene-diones by iron-catalyzed dimerization of isatins0 aEfficient route to 33 biindolinylidenediones by ironcatalyzed di cAUG ae2022004140 v173 a

Iron-catalyzed dimerization of various isatin derivatives is described for the efficient synthesis of 3,3 `-biindolinylidene-diones (isoindigos). The reaction provides easy access to self-coupled and cross-coupled 3,3 `-indolinylidene-diones that have high relevance to biology and materials. This Fe(0)- or Fe(II)-catalyzed dimerization reaction tolerates a wide range of functionalities, such as fluoro, chloro, bromo, alkenyl, nitrile, ether, ester, pyrrolyl, indolyl and carbazolyl groups, including cyclic and acyclic alkyls as well as an alkyl-bearing fatty-alcohol moiety. Especially, the coupling between two distinct isatins provided excellent selectivity for the cross-dimerization with trace of self-couplings. The single-crystal X-ray diffraction study established the molecular structure of eight dimerized products. A preliminary mechanistic study of the Fe-catalyzed dimerization supported the radical pathway for the reaction.

10aCross-coupling10adimerization10airon10aIsatin10aIsoindigo10aMechanism1 aJagtap, Rahul, A.1 aPradhan, Chandini1 aGonnade, Rajesh, G.1 aPunji, Benudhar uhttp://library.ncl.res.in/content/efficient-route-33-biindolinylidene-diones-iron-catalyzed-dimerization-isatins02015nas a2200313 4500008004100000022001400041245013600055210006900191260000800260300001100268490000800279520101300287653001901300653001101319653001401330653002801344653002201372653002001394100001601414700001801430700002101448700002101469700001901490700001301509700002201522700001301544700001301557856013101570 2022 eng d a0960-852400aUnraveling the reaction mechanism of selective C9 monomeric phenols formation from lignin using Pd-Al2O3-activated biochar catalyst0 aUnraveling the reaction mechanism of selective C9 monomeric phen cJAN a1262040 v3443 aThe conversion of biomass-derived lignin to valuable monomeric phenols at high selectivity is of paramount importance for sustainable biorefineries. In this study, a novel Pd-Al2O3 supported on activated biochar catalyst is developed for lignin hydrogenolysis. The catalyst characterization revealed that the (1 1 1) planes of both of Pd-0 and Al2O3 were exposed to the surface. The maximum lignin conversion of 70.4% along with high liquid yield (similar to 57 wt%) was obtained at 240 degrees C, 3 h and 3 MPa H-2 pressure. The total monomeric phenols yield in the liquid was 51.6 wt%, out of which C9 monomeric guaiacols constituted similar to 30.0 wt% with 38.0% selectivity to 4-propyl guaiacol. Using the reaction intermediate, coniferyl alcohol, chemoselective hydrogenation of C-alpha=C-beta is proved to occur over the Pd site, while dehydroxylation of C-gamma-OH is shown to occur over the alumina site. An impressive carbon atom economy of 60% was achieved for the production of monomeric phenols.10aHydrogenolysis10alignin10aMechanism10aPd-Al/activated biochar10aPropanol guaiacol10aPropyl guaiacol1 aGurrala, L.1 aKumar, M., M.1 aYerrayya, Attada1 aKandasamy, Prabu1 aCastano, Pedro1 aRaja, T.1 aPilloni, Giovanni1 aPaek, C.1 aVinu, R. uhttp://library.ncl.res.in/content/unraveling-reaction-mechanism-selective-c9-monomeric-phenols-formation-lignin-using-pd-al2o3