Planar-chiral [2.2]Paracyclophane-based Pyridonates as Ligands for Tantalum-catalyzed Hydroaminoalkylation

By using planar chiral [2.2]paracyclophane-containing N,O-chelating ligands for tantalum-catalyzed hydroaminoalkylation, one of the most versatile catalytic systems for this reaction to date was ob-tained. Convenient Csp3?Csp3 bond formation of amines with terminal and internal alkenes was enabled by the same in situ synthesized catalytic system of [2.2]paracyclophane-based pyridonates and Ta(CH2TMS)3Cl2 (Scheme 1) that shows also very promising results for N-containing heterocycles.By using planar chiral [2.2]paracyclophane-containing N,O-chelating ligands for tantalum-catalyzed hydroaminoalkylation, one of the most versatile catalytic systems for this reaction to date was obtained. Convenient C-sp3-C-sp3 bond formation of amines with terminal and internal alkenes was enabled by the same insitu synthesized catalytic system of [2.2]paracyclophane-based pyridonates and Ta(CH2TMS)(3)Cl-2 that shows also very promising results for N-containing heterocycles.Peer reviewe

State of Nebraska Digital Equity Plan: Understanding the Digital Equity Needs of Covered Populations in Nebraska

According to 2021 estimates from the U.S. Census Bureau’s American Community Survey, 7% of Nebraska households do not have access to a computer and 6% of Nebraska households have access to a computer but no internet. Although recent efforts suggest there is momentum and government action at both the federal and state levels to address lack of broadband (Hammel, 2023; Newman, 2023), this still leaves a considerable number of Nebraskans without access to reliable broadband in the meantime. Furthermore, broadband access is moot if Nebraskans do not have access or cannot afford technology and the cost of internet in the first place. The purpose of this report is to take a deeper look at specific covered populations in Nebraska who are more likely to be without affordable, reliable technology access and, therefore, are disproportionally impacted by the digital divide. The research team, representing the University of Nebraska at Omaha Center for Public Affairs Research and Department of Gerontology, was approached by the Nebraska Information Technology Commission to conduct focus groups with covered populations. Key findings from focus groups are shared. Findings indicate that access to technology and internet is not only vital for all Nebraskans but is also costprohibitive for already marginalized populations. Moving forward, these findings will inform the creation of a state digital equity plan for Nebraska

Titanium pyridonates for the homo- and copolymerization of <i>rac</i>-lactide and ε-caprolactone

A series of titanium pyridonate complexes have been synthesized under very mild reaction conditions from a common precursor, Ti(NMe2)4. These complexes have been explored as initiators for the ring-opening polymerization of rac-lactide and ε-caprolactone and have proven to be competitive with leading titanium initiators.</p

Risk-taking in disorders of natural and drug rewards: neural correlates and effects of probability, valence, and magnitude.

Pathological behaviors toward drugs and food rewards have underlying commonalities. Risk-taking has a fourfold pattern varying as a function of probability and valence leading to the nonlinearity of probability weighting with overweighting of small probabilities and underweighting of large probabilities. Here we assess these influences on risk-taking in patients with pathological behaviors toward drug and food rewards and examine structural neural correlates of nonlinearity of probability weighting in healthy volunteers. In the anticipation of rewards, subjects with binge eating disorder show greater risk-taking, similar to substance-use disorders. Methamphetamine-dependent subjects had greater nonlinearity of probability weighting along with impaired subjective discrimination of probability and reward magnitude. Ex-smokers also had lower risk-taking to rewards compared with non-smokers. In the anticipation of losses, obesity without binge eating had a similar pattern to other substance-use disorders. Obese subjects with binge eating also have impaired discrimination of subjective value similar to that of the methamphetamine-dependent subjects. Nonlinearity of probability weighting was associated with lower gray matter volume in dorsolateral and ventromedial prefrontal cortex and orbitofrontal cortex in healthy volunteers. Our findings support a distinct subtype of binge eating disorder in obesity with similarities in risk-taking in the reward domain to substance use disorders. The results dovetail with the current approach of defining mechanistically based dimensional approaches rather than categorical approaches to psychiatric disorders. The relationship to risk probability and valence may underlie the propensity toward pathological behaviors toward different types of rewards.This is the final version. It was first published by NPG at http://www.nature.com/npp/journal/v40/n4/full/npp2014242a.htm

Zirconium catalyzed alkyne dimerization for selective Z-enyne synthesis

The regioselective head-to-head dimerization of alkynes is catalyzed by a dibenzyl tethered bis(ureate) zirconium precatalyst with aniline as an additive. This system also gives outstanding stereoselectivity to furnish Z-enynes in high yields. A dinuclear reactive intermediate has been characterized, which provides a potential mechanistic rationale for the unexpected regio- and stereoselectivity in this catalytic system

2‑Pyridonate Titanium Complexes for Chemoselectivity. Accessing Intramolecular Hydroaminoalkylation over Hydroamination

Chemoselectivity of intramolecular hydroaminoalkylation over hydroamination has been achieved with a bis(3-phenyl-2-pyridonate) titanium complex. Primary aminoalkenes are selectively α-alkylated by C–H functionalization adjacent to nitrogen to access five- and six-membered cycloalkylamines with a good substrate-dependent diastereoselectivity of up to 19:1

2‑Pyridonate Titanium Complexes for Chemoselectivity. Accessing Intramolecular Hydroaminoalkylation over Hydroamination

Chemoselectivity of intramolecular hydroaminoalkylation over hydroamination has been achieved with a bis(3-phenyl-2-pyridonate) titanium complex. Primary aminoalkenes are selectively α-alkylated by C–H functionalization adjacent to nitrogen to access five- and six-membered cycloalkylamines with a good substrate-dependent diastereoselectivity of up to 19:1

Mechanistic Elucidation of Intramolecular Aminoalkene Hydroamination Catalyzed by a Tethered Bis(ureate) Complex: Evidence for Proton-Assisted C-N Bond Formation at Zirconium

A broad mechanistic investigation regarding hydroamination reactions catalyzed by a tethered bis(ureate) zirconium species, [ureate(2-)]Zr(NMe(2))(2)(HNMe(2)), is described. The cyclization of both primary and secondary aminoalkene substrates gives similar kinetic profiles, with zero-order dependence on substrate concentration up to similar to-60-75% conversion, followed by first-order dependence for the remainder of the reaction. The addition of 2-methylpiperidine changes the observed substrate dependence to first order throughout the reaction, but does not act as a competitive inhibitor. The reactions are first order in precatalyst up to loadings of similar to 0.15 M, indicating that a well-defined, mononuclear catalytic species is operative. Several model complexes have been structurally characterized, including dimeric imido and amido species, and evaluated for catalytic performance. These results indicate that imido species need not be invoked as catalytically relevant intermediates, and that the mono(amido) complex [ureate(2-)]Zr(NMe(2))(Cl)(HNMe(2)) is much less active than its bis(amido) counterpart. Structural evidence suggests that this is due to differences in coordination geometry between the mono- and bis(amido) complexes, and that an equatorial amido ligand is required for efficient catalytic turnover. On the basis of the determination of kinetic isotope effects and stoichiometric reactivity, the catalytic turnover-limiting step is proposed to be a concerted C-H, C-N bond-forming process with a highly ordered, unimolecular transition state (Delta S(double dagger) = -21 +/- 1 eu). In addition to this key bond-forming step, the catalytic cycle involves an on-cycle pre-equilibrium between six- and seven-coordinate intermediates, leading to the observed switch from zero- to first-order kinetics