Doylefletcher2308

A palladium-catalyzed cross-coupling between in situ generated allenyl/propargyl-lithium species and aryl bromides to yield highly functionalized allenes is reported. The direct and selective formation of allenic products preventing the corresponding isomeric propargylic product is accomplished by the choice of SPhos or XPhos based Pd catalysts. The methodology avoids the prior transmetalation to other transition metals or reverse approaches that required prefunctionalization of substrates with leaving groups, resulting in a fast and efficient approach for the synthesis of tri- and tetrasubstituted allenes. Experimental and theoretical studies on the mechanism show catalyst control of selectivity in this allene formation. Selleck SR-18292 © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.Chiral 1,2-bimetallic reagents are useful motifs in synthetic chemistry. Although  syn -1,2-bimetallic compounds can be prepared by alkene dimetallation,  anti -1,2-bimetallics are still rare. The stereospecific 1,2-metallate shift that occurs during conjunctive cross-coupling is shown to enable a practical and modular approach to the catalytic synthesis of enantioenriched  anti -1,2-borosilanes.  In addition to reaction development, the synthetic utility of  anti -1,2-borosilanes was investigated, including applications to the synthesis of  anti -1,2-diols and  anti -1,2-amino alcohols. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.We report the first examples of catalytic enantioselective benzilic ester rearrangement reaction. In the presence of a catalytic amount of Cu(OTf)2 and a chiral box ligand under mild conditions, reaction of 2,3-diketoesters with alcohols afforded structurally diverse α-aryl(alkyl) substituted-α-hydroxy malonates (tartronic esters) in good to excellent yields with high enantioselectivities. Preliminary mechanistic studies indicated that hemiketalization, rather than the dynamic kinetic resolution of hemiketal, was the enantiodetermining step under our reaction conditions. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.The nematic twist-bend (NTB ) liquid crystal phase possesses a local helical structure with a pitch length of a few nanometres and is the first example of spontaneous symmetry breaking in a fluid system. All known examples of the NTB phase occur in materials whose constituent mesogenic units are aromatic hydrocarbons. It is not clear if this is due to synthetic convenience or a bona fide structural requirement for a material to exhibit this phase of matter. In this work we demonstrate that materials consisting largely of saturated hydrocarbons can also give rise to this mesophase. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.Nickel iron oxyhydroxide is the benchmark catalyst for the oxygen evolution reaction (OER) in alkaline medium. Whereas the presence of Fe ions is essential to the high activity, the functions of Fe are currently under debate. Using oxygen isotope labeling and operando Raman spectroscopic experiments, we obtain turnover frequencies (TOFs) of both Ni and Fe sites for a series of Ni and NiFe layered double hydroxides (LDHs), which are structurally defined samples of the corresponding oxyhydroxides. The Fe sites have TOFs 20-200 times higher than the Ni sites such that at an Fe content of 4.7 % and above the Fe sites dominate the catalysis. Higher Fe contents lead to larger structural disorder of the NiOOH host. A volcano-type correlation was found between the TOFs of Fe sites and the structural disorder of NiOOH. Our work elucidates the origin of the Fe-dependent activity of NiFe LDH, and suggests structural ordering as a strategy to improve OER catalysts. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.In recent decades, a paradigm shift in forest management and associated policies has led to greater emphasis on harvest practices that retain mature, overstory trees in forest stands that would otherwise be clearcut. While it is often assumed that the maintenance of compositional and structural complexity, such as that achieved through retention forestry approaches, will also mitigate negative impacts to functional diversity, empirical evidence of this relationship is sparse. We examined the effects of an aggregated retention system on taxonomic and functional diversity in a regenerating aspen-dominated forest. Sampling was conducted along transects arranged to capture the transition from harvested (regenerating) forest to mature, unharvested forest (both intact forest stands and 0.1 ha retention aggregates). We then assessed the magnitude and distance of edge effects on multiple indices of taxonomic and functional diversity as well as functional identity. Twelve years after harvest, the distance and magnitude of edge effects on functional and taxonomic diversity did not differ between the two unharvested patch sizes (intact vs. aggregate); however, intact forest exhibited greater resistance to edge effects and greater depth of edge influence into harvested areas for some traits compared to aggregates. Analyses relying on functional traits were generally applicable across sites within a highly variable forest type, and our results demonstrate the promise of using functional traits to assess management impacts on plant diversity across a landscape. Aggregates maintained some functional attributes associated with interior forest and influenced adjacent regeneration. However, trends in some traits (i.e. shade tolerance and seed mass), particularly in the seedling layer, suggest aggregates of this size provide primarily edge habitat. This article is protected by copyright. All rights reserved.Immobilization of compartmentalized microscale objects in 3D hydrogels provides a step towards the modular assembly of soft functional materials with tunable architectures and distributed functionalities. Herein, we report the use of a combination of micro-compartmentalization, immobilization, and modularization to fabricate and assemble hydrogel-based microreactor assemblies comprising millions of functionalized polysaccharide-polynucleotide coacervate droplets. The heterogeneous hydrogels can be structurally fused by interfacial crosslinking and coupled as input and output modules to implement a UV-induced photocatalytic/peroxidation nanoparticle/DNAzyme reaction cascade that generates a spatiotemporal fluorescence read-out depending on the droplet number density, intensity of photoenergization, and chemical flux. Our approach offers a route to heterogeneous hydrogels with endogenous reactivity and reconfigurable architecture, and provides a step towards the development of soft modular materials with programmable functionality. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.In hunting for safe and cost-effective materials for post lithium-ion energy storage systems, design and synthesis of high-performance solid electrolytes (SEs) are currently bottlenecks for all-solid-state batteries. Many issues need to be addressed, such as chemical stability during processing, storing and using in ambient condition. Therefore, we investigate the effect of water as well as oxyhdryl group (▪OH) on NaBi 3 O 4 Cl 2 through evaluating ionic conductivity. It is noted that presence of water and ▪OH results in an increase in ionic conductivity of NaBi 3 O 4 Cl 2 due to the diffusion of H 2 O into NaBi 3 O 4 Cl 2 and partially forming binding ▪OH through oxygen vacancy repairing. Furthermore, Ab intio calculation reveals that the electrons significantly accumulate around ▪OH and induce a more negative charge center which can promote Na + hopping. This finding provides a fundamental for understanding the essential role of H 2 O in halide-based SEs and hence provides possible roles in designing water-insensitive SEs through defects control. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.The concept of anion-π catalysis focuses on the stabilization of anionic transition states on aromatic π surfaces. Recently, we demonstrated the occurrence of epoxide-opening ether cyclizations on aromatic π surfaces. Although the reaction proceeded through unconventional mechanisms, the obtained products are the same as those from conventional Brønsted acid catalysis, and in agreement with the Baldwin selectivity rules. Different mechanisms, however, should ultimately lead to new products, a promise anion-π catalysis has been reluctant to live up to. Herein, we report non-trivial reactions that work with anion-π catalysis, but not with Brønsted acids, under comparable conditions. Namely, we show that the anion-π templated autocatalysis and epoxide opening with alcoholate-π interactions can provide access to unconventional ring chemistry. For smaller rings, anion-π catalysis affords anti-Baldwin oxolanes, 2-oxabicyclo[3.3.0]octanes, and the expansion of Baldwin oxetanes by methyl migration. link2 For larger rings, anion-π templated autocatalysis is thought to alleviate the entropic penalty of folding to enable disfavored anti-Baldwin cyclizations into oxepanes and oxocanes. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.OBJECTIVE Characterization of partial remission using the insulin dose-adjusted HbA1c (IDAA1c) ≤ 9 definition in a multiethnic Brazilian population of children and adolescents with type 1 diabetes (T1D), in addition with the determination of both Class II HLA genotype and autoantibodies. METHODS We analyzed the prevalence of partial remission in 51 new-onset T1D patients with a median time follow-up of 13 months from diagnosis. For this study, anti-GAD65, anti-IA2 and HLA class II genotyping were considered. RESULTS Partial remission occurred in 41.2% of T1D patients until 3 months after diagnosis, mainly in those aged 5-15 years. We have demonstrated a significant increase in the haplotypes of class II HLA DRB1*0301-DQB1*0201 in children and adolescents with a partial remission phase of the disease (42.9% vs 21.7% in non-remitters, P = .0291). link3 This haplotype was also associated with the reduction of anti-IA2 antibodies production. Homozygote DRB1*03-DQB1*0201/DRB1*03-DQB1*0201 children had the lowest prevalence of IA-2A antibodies (P = .0402). However, this association does not correlate with the time of the remission phase. CONCLUSION Although the number of patients studied was reduced, our data suggested that the association between genetics and decrease in antibody production to certain islet auto-antigen may contribute, at least in part, to the remission phase of T1D. © 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.OBJECTIVES The prevalence and burdens of obesity-associated chronic conditions (OCC) are rising nationwide, particularly in health professional shortage areas (HPSA). This study examined the impact of access to primary care on health care utilization for vulnerable populations with OCC in the South. METHODS Adult patients with obesity (BMI ≥ 30 kg/m2 ), greater than or equal to one additional OCC, and self-reported primary care access data were retrospectively identified from hospital and emergency department (ED) electronic medical records of a major health care system in the South. Multivariable logistic regression assessed factors associated with self-reported access to primary care. Multivariable zero-inflated negative binomial models assessed effect of HPSA residence on relationships between self-reported access to primary care and health care utilization. RESULTS A total of 29 674 patients were identified. Hypertension (76.1%), type 2 diabetes mellitus (34.1%), and hyperlipidemia (32.9%) were the most prevalent OCC.