The cascade dimerization of alkynones bearing sterically hindered secondary alkyl groups at the carbonyl function has unexpectedly furnished highly functionalized furans. The reaction efficiently ...occurs in the presence of potassium tert‐butoxide/dimethylsulfoxide superbase catalytic system at room temperature. Alkynones having additional C−H active site at the carbon‐carbon triple bond have followed another dimerization pathway to afford 3‐alkenylpyran‐4‐ones. The discovery of these reactions expands the traditional knowledge about the reactivity of alkynones in strong basic medium.
Novel superbase‐catalyzed dimerization pathways of widely‐applicable substrates, namely alkynones, have been discovered and thoroughly studied.
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BFBNIB, FZAB, GIS, IJS, KILJ, OILJ, SBCE, SBMB, UPUK
There is currently limited information as to which conditions are most prevalent in communities in developing countries. This makes effective planning of eye services difficult.
3,899 eligible ...individuals were recruited and examined in a cross-sectional survey in Asa Local Government Area, Nigeria. Those who self-reported an ocular morbidity were also asked about their health-seeking behaviour. Health records of local facilities were reviewed to collect information on those presenting with ocular morbidities.
25.2% (95% CI: 22.0-28.6) had an ocular morbidity in at least one eye. Leading causes were presbyopia and conditions affecting the lens and conjunctiva. The odds of having an ocular morbidity increased with age and lower educational attainment. 10.1% (7.7-13.0) self-reported ocular morbidity; 48.6% (40.4-56.8) of them reported seeking treatment. At the facility level, 344 patients presented with an ocular morbidity over one month, the most common conditions were red (26.3%) or itchy (20.8%) eyes.
Ocular morbidities, including many non vision impairing conditions, were prevalent with a quarter of the population affected. The delivery of eye care services needs to be tailored in order to address this need and ensure delivery in a cost-effective and sustainable manner.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Patterns of differential selectivity of two competing unsaturated substrates along with differential regioselectivity of α‐ and β‐regioisomers of arylated products formed in Heck reactions with aryl ...halides or with aromatic carboxylic anhydrides as well as differential regioselectivity of C2‐ and C3‐arylated indoles in direct C−H arylation with aryl halides unambiguously evidence that the commonly accepted mechanistic scheme of unsaturated substrate activation the Heck‐type coupling reactions needs to be revised. Comprehensive kinetic study points to the activation of aryl halide and unsaturated substrate by two distinct Pd species, as well as existence of an additional intermediate of their catalytic cycles being not taken into consideration earlier in the mechanistic schemes of the reactions.
Comprehensive kinetic study of Heck and related reactions points to the activation of aryl halide and unsaturated substrate by two distinct Pd species, as well as existence of an additional intermediate of their catalytic cycles being not taken into consideration earlier in the mechanistic schemes of the reactions
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
We have discovered that three molecules of arylacetylene are rapidly (15 min) assembled with one molecule of nitrile at room temperature in the KOBut/DMSO system to afford ...2-aryl-3-arylethynyl-4-aryl-5-benzyl-1H-pyrroles in up to 76% yield. We assume that this unprecedented self-organization process involves the cascade addition of acetylenic carbanions, first to the C≡N, then to the C≡C and C=C bonds of the intermediates, followed by pyrrole ring closure via the intramolecular nucleophilic addition of the NH functional group to the C≡C bond of the final intermediates.
2-Acetyl-3,4-dihydropyrans, assembled from acetylene gas and ketones in a one-pot procedure, are ethynylated with acetylenes (KOBu
t
/DMSO, 15 °C, 2 h) to give acetylenic alcohols, which readily ...cyclize (TFA, rt, 5 min) to 7-ethynyl-6,8-dioxabicyclo3.2.1octanes in up to 92% yield. The ring closure of the above acetylenic alcohols can be performed without their isolation from the reaction mixture. Thus, the synthesis of 7-ethynyl-6,8-dioxabicyclo3.2.1octanes can be realized in just two synthetic operations from simple and available starting materials under mild transition-metal-free conditions.
A new family of natural-related bicyclic ketals became readily accessible in a simple atom-economic two-step procedure from acetylenes and ketones under mild transition-metal-free conditions.
Dienyl derivatives of 6,8-dioxabicyclo3.2.1octanes, closely related to naturally abundant molecules, have been synthesized from 2-acetyl-3,4-dihydropyrans (readily available from ketones and ...acetylene in two steps), which further add to aryl(hetaryl)acetylenes in the KOBut/DMSO superbase system (105 °C, 1.5 h) to stereoselectively give the corresponding E-styryl adducts. The latter undergo ring closure (NH4Cl/H2O, acetonitrile, reflux, 8 h) to form the 6,8-dioxabicyclo3.2.1octane core decorated with the (1Z,3E)-diene substituent.
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IJS, KILJ, NUK, PNG, UL, UM
No compound has generated more attention in both the scientific and recently in the political arena as much as cannabinoids. These diverse groups of compounds referred collectively as cannabinoids ...have both been vilified due to its dramatic and potentially harmful psychotropic effects and glorified due to its equally dramatic and potential application in a number of acute and chronic neurological conditions. Previously illegal to possess, cannabis, the plant where natural form of cannabinoids are derived, is now accepted in a growing number of states for medicinal purpose, and some even for recreational use, increasing opportunities for more scientific experimentation. The purpose of this review is to summarize the growing body of literature on cannabinoids and to present an overview of our current state of knowledge of the human endocannabinoid system in the hope of defining the future of cannabinoids and its potential applications in disorders of the central nervous system, focusing on stroke.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
As prevalence decreases in pre-elimination settings, identifying the spatial distribution of remaining infections to target control measures becomes increasingly challenging. By measuring multiple ...antibody responses indicative of past exposure to different pathogens, integrated serological surveys enable simultaneous characterisation of residual transmission of multiple pathogens.
Here, we combine integrated serological surveys with geostatistical modelling and remote sensing-derived environmental data to estimate the spatial distribution of exposure to multiple diseases in children in Northern Ghana. The study utilised the trachoma surveillance survey platform (cross-sectional two-stage cluster-sampled surveys) to collect information on additional identified diseases at different stages of elimination with minimal additional cost. Geostatistical modelling of serological data allowed identification of areas with high probabilities of recent exposure to diseases of interest, including areas previously unknown to control programmes. We additionally demonstrate how serological surveys can be used to identify areas with exposure to multiple diseases and to prioritise areas with high uncertainty for future surveys. Modelled estimates of cluster-level prevalence were strongly correlated with more operationally feasible metrics of antibody responses.
This study demonstrates the potential of integrated serological surveillance to characterise spatial distributions of exposure to multiple pathogens in low transmission and elimination settings when the probability of detecting infections is low.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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