Regioselective C(sp2)-H imidation of arenes by redox neutral visible-light photocatalysis.

We report herein a redox neutral visible light-induced regioselective C(sp2)-H imidation of electron-rich arenes and heteroarenes using conceptually designed redox-active 1 as a source of the N-centered imidyl radical. Structurally diverse aromatic imides were obtained in moderate to good yields. This methodology has been successfully employed for the late stage imidation of complex molecules and has also been applied towards the formal total synthesis of the marine natural products carpatamides A, B and D. It has further been shown that the generated imides can easily be converted to the corresponding anilines in situ directly.

Chemical composition, pesticidal activities and in-silico investigation of Hedychium spicatum Sm. chloroform extract.

The present study aimed to identify the bioactive constituents in the chloroform extract of H. spicatum rhizomes (HS-RCLE), further evaluated for its in-vitro pesticidal activities validating via molecular docking techniques. GC/MS analysis of HS-RCLE identified 14 compounds contributing 84.1 % of the total composition. The extract was dominated by oxygenated sesquiterpenes (43.1 %) with curcumenone (25.2 %) and coronarin E (14.8 %) as the major compounds. The extract recorded 89.4 % egg hatchability inhibition and 82.6 % immobility of Meloidogyne incognita, 66.7 % insecticidal activity on Spodoptera litura, 100 % phytotoxic activity on Raphanus raphanistrum seeds, and 74.7 % anti-fungal activity on Curvularia lunata at the respective highest dose studied. The biological activities were furthermore validated by using docking studies on certain proteins/enzymes namely acetylcholinesterase (PBD ID: IC2O), carboxylesterase (PDB ID: 1CI8), acetohydroxyacid synthase (PBD ID: 1YHZ) and trihydroxy naphthalene reductase (PBD ID: 3HNR). The bioactivity of the major constituents of the extract was predicted with the help of in silico PASS studies. HS-RCLE was observed to be a viable alternative source of natural pesticidal agents and paves the way for further studies on its mechanistic approaches and field trials to ascertain its pesticidal studies.

Direct Arylation of Distal and Proximal C(sp3)-H Bonds of t-Amines with Aryl Diazonium Tetrafluoroborates via Photoredox Catalysis.

A visible light-mediated arylation protocol for t-amines has been reported through the coupling of γ- and α-amino alkyl radicals with different aryl diazonium salts using Ru(bpy)3Cl2·6H2O as a photocatalyst. Structurally different 9-aryl-9,10-dihydroacridine, 1-aryl tetrahydroisoquinoline, hexahydropyrrolo[2,1-a]isoquinoline, and hexahydro-2H-pyrido[2,1-a]isoquinoline frameworks with different substitution patterns have been synthesized in good yield using this methodology.

Diversity-Oriented Approach Toward the Syntheses of Amaryllidaceae Alkaloids via a Common Chiral Synthon.

Functionalized hydroindole (1), a common chiral synthon, for versatile transformations to synthesize a broad range of Amaryllidaceae alkaloids (AAs) including (-)-crinine, (-)-crinane, (-)-amabiline, (+)-mesembrine, (-)-maritidine, (-)-oxomaritidine, and (+)-mesembrane is reported. Scaffold 1 is found as a prime structural motif in a wide variety of the AAs and is a novel synthon toward designing a divergent route for the synthesis of these natural products. This is established in a few steps, starting from a chiral aza-bicyclo-heptene sulfone scaffold (2) via conjugate addition and concomitant stereoselective ring opening with allylmagnesium bromide, a key step that generates a crucial quaternary stereocenter, fixing the stereochemistry of the rest of the molecule at an early stage. One carbon truncation followed by intramolecular reductive amination led to the desired core 1 in a multigram scale.

Benzylic C(sp(3))-H Functionalization for C-N and C-O Bond Formation via Visible Light Photoredox Catalysis.

A visible light mediated highly selective benzylic C-H bond functionalization for intermolecular C-N and C-O bond formation is reported. This cross-dehydrogenative coupling reaction demonstrates a straightforward protocol for incorporating the heteroaromatics to the benzylic position. Benzylic oxidation of various alkyl aryls to corresponding carbonyl compounds has also been reported.

Aza-Quaternary Scaffolds from Selective Bond Cleavage of Bridgehead-Substituted 7-Azabicyclo[2.2.1]heptane: Total Synthesis of (+)-Cylindricines†C-E and (-)-Lepadiformine†A.

A novel bridgehead-substituted aza-bicyclic framework has been designed and developed in both enantiomeric forms through an asymmetric desymmetrization reaction. Strategic exploitation of the ring strain in the aza-bicyclic framework has been utilized for the construction of the chiral aza-quaterenary scaffolds by selective bond fragmentation processes. Furthermore, a strategically designed precursor is employed for selective bond cleavage to initiate a cascade rearrangement for the total synthesis of the 1-azaspirotricyclic marine alkaloids (+)-cylindricines C, D, and E, as well as (-)-lepadiformine A. An oxidation/retro-aldol/aza-Michael sequence generated three new chiral centers with the required configuration in one pot.

Efficient access to enantiopure 1,3-disubstituted isoindolines from selective catalytic fragmentation of an original desymmetrized rigid overbred template.

An efficient and scalable synthesis of various enantiopure 1,3- disubstituted isoindolines is reported. The base catalyzed nucleophilic fragmentation of a rigid overbred template is established with various substrates to afford the corresponding 1,3-disubstituted isoindoline ester, amide, thioate, 1,3-amino alcohol and isoindolylcarboxylic acid. The crucial rigid overbred template is synthesized in an optically pure form in multigram scale by asymmetric desymmetrization of the corresponding meso compound.

The socio-economic determinants of infant mortality in Nepal: analysis of Nepal Demographic Health Survey, 2011.

BACKGROUND: Infant mortality reflects not only the health of infants but societal well-being as a whole. This study explores distal socioeconomic and related proximate determinants of infant mortality and provides evidence for designing targeted interventions. METHODS: Survival information on 5391 live born infants (2006-2010) was examined from the nationally representative Nepal Demographic Health Survey 2011. Bivariate logistic regression and multivariate hierarchical logistic regression approaches were performed to analyze the distal-socioeconomic and related proximate determinants of infant mortality. RESULTS: Socio-economic distal determinants are important predictors for infant mortality. For example, in reference to infants of the richest class, the adjusted odds ratio of infant mortality was 1.66 (95% CI: 1.00-2.74) in middle class and 1.87 (95% CI: 1.14-3.08) in poorer class, respectively. Similarly, the populations of the Mountain ecological region had a higher odds ratio (aOR =1.39, 95% CI: 0.90-2.16) of experiencing infant mortality compared with the populations of the Terai plain region. Likewise, the population of Far-western development region had a higher adjusted odds ratio (aOR =1.62, 95% CI: 1.02-2.57) of experiencing infant mortality than the Western development region. Moreover, the association of proximate determinants with infant mortality was statistically significant. For example, in reference to size at birth, adjusted odds ratio of infant dying was higher for infants whose birth size, as reported by mothers, was very small (aOR = 3.41, 95% CI: 2.16-5.38) than whose birth size was average. Similarly, fourth or higher birth rank infants with a short preceding birth interval (less than or equal to 2 years) were at greater risk of dying (aOR =1.74, 95% CI: 1.16-2.62) compared to the second or third rank infants with longer birth intervals. A short birth interval of the second or the third rank infants also increased the odds of infant death (aOR = 2.03, 95% CI: 1.23-3.35). CONCLUSIONS: Socioeconomic distal and proximate determinants are associated with infant mortality in Nepal. Infant mortality was higher in the poor and middle classes than the wealthier classes. Population of Mountain ecological region and Far western development region had high risk of infant mortality. Similarly, infant dying was higher for infants whose birth size, as reported by mothers, was very small and who has higher birth rank and short preceding birth interval. This study uniquely addresses both broader socioeconomic distal and proximate determinants side by side at the individual, household and community levels. For this, both comprehensive, long-term, equity-based public health interventions and immediate infant care programs are recommended.

Visible-Light-Catalyzed Direct Benzylic C(sp(3))-H Amination Reaction by Cross-Dehydrogenative Coupling.

A conceptually new and synthetically valuable cross-dehydrogenative benzylic C(sp(3))-H amination reaction is reported by visible-light photoredox catalysis. This protocol employs DCA (9,10-dicyanoanthracene) as a visible-light-absorbing photoredox catalyst and an amide as the nitrogen source without the need of either a transition metal or an external oxidant.

α-Trimethylsilylmethylamine radical cation in the synthesis of cyclic amines and beyond.

The evolution of chemistry associated with the photoinduced electron transfer (PET)-generated α-trimethylsilylmethylamine radical cation cyclization to a tethered olefin to synthesize cyclic amine structural frame works is presented in chronological order. The importance of this interesting chemistry is demonstrated by the synthesis of several novel glycosidase inhibitors.

Characterizing Properties of Biomolecular Condensates Below the Diffraction Limit In Vivo.

Fluorescence microscopy assays enable the investigation of endogenous biomolecular condensates directly in their cellular context. With appropriate experimental designs, these assays yield quantitative information on condensate material properties and inform on biophysical mechanisms of condensate formation. Single-molecule super-resolution and tracking experiments grant access to the smallest condensates and early condensation stages not resolved by conventional imaging approaches. Here, we discuss considerations for using single-molecule assays to extract quantitative information about biomolecular condensates directly in their cellular context.

Sustainable ceramic membrane for decontamination of water: A cost-effective approach.

A sustainable ceramic membrane embedded with silver has been developed using quartz, kaolin and calcium carbonate. All the chemicals involved in this process were commonly available, non-toxic and cheap. The process was very simple, convenient and does not involve any wastage of water. Decoration of silver particles onto the porous ceramic membrane with the help of APTES as a connecting molecule leads to the formation of a durable material having strong antibacterial capacity. The fabricated membrane holds wide pore morphology with pore size of 4.4 µm and average porosity of 19.5% with an estimated cost of fabrication of about 60 dollar/m2. The membrane was found capable in reducing the TDS, BOD and COD of water samples that confirms that it is efficient for water treatment applications.

Organocatalytic dynamic kinetic resolution via conjugate addition: synthesis of chiral trans-2,5-dialkylcyclohexanones.

A novel strategy of initiating an organocatalysed dynamic kinetic resolution (dr up to 99 : 1 and er up to 94 : 6) for the synthesis of chiral trans-2,5-dialkylcyclohexanones by an asymmetric conjugate addition of dimethyl malonate on to 6-substituted cyclohexenones is reported.

p-Silylation of Arenes via Organic Photoredox Catalysis: Use of p-Silylated Arenes for Exclusive o-Silylation, o-Acylation, and o-Alkylation Reactions.

Photocatalytic regiospecific p-silylation of arenes has been achieved by the coupling of in situ generated silyl radical with arene radical cation. The strategy involves reductive activation of PhSe-SiR3 and single electron transfer from the electron rich arene to 9,10-dimethoxyanthracene radical cation (DMA•+). p-Silyl arenes, thus formed, are further utilized for exclusive o-silylation reaction and for regiospecific o-acylation as well as o-alkylation reaction.

Approaches to synthesize MgO nanostructures for diverse applications.

Magnesium oxide remained interesting from long time for several important phenomena like; defect induced magnetism, spin electron reflectivity, broad laser emission etc. Moreover, nanostructures of this material exhibited suitability for different kinds of applications ranging from wastewater treatment to spintronics depending upon their shape and size. In this way, researchers had grown nanostructures in the form of nanoparticles, thin films, nanotubes, nanowalls, nanobelts. Though nanoparticles and thin films are well known form of nanostructures and wide variety of synthesis approaches are available, however, limited methodology for other nanostructures are available. In order to grow these nanostructures in an optimized way an understanding of these methods is essential. Thus, this review article depicts an overview of various approaches for design of different kinds of nanostructures.

Synthesis of polyfunctional quinolizidine alkaloids: development towards selective glycosidase inhibitors.

A highly divergent route to a variety of quinolizidine alkaloids is described. The enantiomeric precursors and utilized for the synthesis of these alkaloids were constructed stereospecifically from the PET cyclization of the corresponding acetylene tethered alpha-trimethylsilyl amine moieties and , respectively, both of which were synthesised from D-ribose. The polyhydroxy quinolizidine alkaloid was found to be a selective inhibitor of alpha-galactosidase with Ki 83.9 microM. The amine analogs , and are found to be selective and potent inhibitors of alpha-glucosidase with Ki 28, 120 and 140 microM, respectively.

Heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis.

A general and efficient method for heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis to access a wide range of structurally diverse oxygen as well as nitrogen heterocycles up to a gram scale is reported. The potential application of this new methodology is demonstrated by the total synthesis of (-)-codonopsinine and (+)-centrolobine. Herein it is proposed that selectfluor, unlike a fluorinating reagent, acts as an oxidative quencher and a hydrogen radical acceptor.

Suzuki cross-coupling/reductive debenzyloxycarbonylation sequence for the syntheses of [c]annulated isoquinolines: application for the syntheses of pancratistatin-like isoquinolines.

A two-step strategy involving Suzuki cross-coupling of boronic acids with a diverse array of alpha-iodoenones followed by hydrogenation is developed for the construction of [c]annulated isoquinolines. This mild and efficient procedure is also applied to the synthesis of highly oxygenated isoquinolines.

Generation of All-Carbon Quaternary Stereocenters at the C-3 Carbon of Lactams via [3,3]-Sigmatropic Rearrangement and Revision of Absolute Configuration: Total Synthesis of (-)-Physostigmine.

A diastereoselective (up to >99%) route to all carbon quaternary stereocenters at the C-3 position of cyclic lactams has been developed via Johnson-Claisen rearrangement of γ-hydroxy-α,ß-unsaturated lactams. It has been observed that olefin geometry plays an important role in the development of the absolute stereochemistry of the product. Dependence of product configuration on the olefin geometry is explained by postulating probable transition states. The success of this method has been shown for multigram-scale synthesis of these substituted lactams from commercially available cheap starting materials. The synthetic usefulness of this method is also demonstrated by carrying out the total synthesis of (-)-physostigmine.