This is an overview of successes in the realm of catalytic homogeneous asymmetric hydrogenation of substrates primarily of interest in the synthesis of pharmaceuticals in order to identify important ...problems still unsolved. First, tables are provided that list the successful reductions to over 90% enantiomeric excess of prochiral ketones to alcohols, imines to amines, and olefins to saturated carbon centers. Noted in the tables are the metal (including “green” metals Mn, Fe, and Co) or enzyme, the class of ligand, the conditions of the medium, and the scale of reduction, if over 1 kg of product, as well as the nature of the process, whether direct hydrogenation using H2 gas (DH), transfer hydrogenation (TH), or hydrogenation with dynamic kinetic resolution (DKR). Tables of representative pharmaceutical or fine chemicals products are provided for each class of substrate. With this overview, the opportunities for further research and development become clearer.
Coronary computed tomographic angiography (coronary CT) is a non-invasive test for diagnosis of cardiac function. Coronary calcium scores determined by coronary CT are associated with cardiovascular ...risk factors. However, no studies have investigated the association between coronary calcium scores and cardiovascular complications after liver transplantation (LT). We therefore evaluated the utility of preoperative coronary calcium scores for predicting early postoperative cardiovascular complications in LT recipients.
Between 2010 and 2012, 443 LT recipients were analysed retrospectively. Preoperative cardiovascular assessments, including coronary CT, were performed. A coronary calcium score >400 was defined as a positive finding. Predictive factors of early postoperative cardiovascular complications were evaluated by univariate and multivariate analyses. Major cardiovascular complications occurring during a period of 1 month after LT were noted.
Of the 443 patients, 38 (8.6%) experienced one or more cardiovascular complications. Positive coronary CT findings were seen in 11 (2.5%) patients. In the multivariate analysis, a coronary calcium score >400 {odds ratio (OR)=4.62 95% confidence interval (CI): 1.14–18.72, P=0.032} and female sex OR=2.76 (1.37–5.57), P=0.005 were predictive of cardiovascular complications.
A preoperative coronary calcium score of >400 predicted cardiovascular complications occurring 1 month after LT, suggesting that preoperative evaluation of coronary calcium scores could help predict early postoperative cardiovascular complications in LT recipients.
Yogurt is a healthy dairy food fermented by lactic acid bacteria (LAB). Because consumers demand healthier and more nutritious yogurt, numerous substances have been used to supplement yogurt. Chia ...seed has been reported to contain abundant phenolic compounds, dietary fiber, and n-3 fatty acids and therefore is a potential functional food additive. The aim of this study was to investigate the influence of chia seed extracts on the physicochemical and bioactive properties of set-type yogurt. Yogurt was fortified with chia seed water extract (CSWE) or chia seed ethanol extract (CSEE) at 0.05 or 0.1% (vol/vol). Results showed that supplementation with CSWE or CSEE significantly accelerated the fermentation rate and growth of LAB. Both CSWE and CSEE improved the viscosity, syneresis, and water-holding capacity of yogurt. The radical scavenging activity of yogurt was increased with both extracts, and the 0.1% CSEE yogurt exhibited the highest radical scavenging activity. Furthermore, 0.1% CSEE yogurt significantly inhibited lipopolysaccharide-induced production of hydrogen peroxide in human colon cells. Addition of chia seed extract improves the growth of LAB, the physiochemical properties, and the health-beneficial effects of set-type yogurt.
Chiral amines are key building blocks in synthetic chemistry with numerous applications in the agricultural and pharmaceutical industries. Asymmetric imine hydrogenation, particularly with iridium ...catalysts, is well developed. However, imine reduction still remains challenging in the context of replacing such a precious metal with a cheap, nontoxic, and environmentally friendly substitute such as iron. Here, we report that an unsymmetrical iron P-NH-P′ catalyst that was previously shown to be effective for the asymmetric hydrogenation of aryl ketones is also a very effective catalyst for the asymmetric hydrogenation of prochiral aryl imines activated with N-diphenylphosphinoyl or N-tosyl groups. The P-NH-P′ abbreviation stands for (S,S)-PPh2CHPhCHPhNHCH2CH2P i Pr2. Density functional theory results suggest that, surprisingly, the NH group on the catalyst activates and orients the imine to hydride attack by hydrogen bonding to the PO or SO group on the imine nitrogen, as opposed to the imine nitrogen itself. This may explain why N-Ph and N-Bu imines are not hydrogenated.
Objectives: To examine the prevalence of sarcopenia and sarcopenic obesity (SO) as defined by different indices, including appendicular skeletal muscle mass (ASM)/height2, skeletal muscle mass index ...(SMI) and residuals for Korean adults, and to explore the association between SO and metabolic syndrome. Methods: Our study sample included 526 participants (328 women, 198 men) for whom complete data on body composition were collected using available dual X-ray absorptiometry. Modified National Cholesterol Education Program Adult Treatment Panel III criteria were used to identify the individuals with metabolic syndrome. Results: The prevalence of sarcopenia and SO is higher in older adults. Using two s.d. of ASM/height2 below reference values from young, healthy adults as a definition of sarcopenia, the prevalence of sarcopenia and SO was 6.3% and 1.3% in older (60 years) men and 4.1% and 0.8% in older women, respectively. The prevalence of sarcopenia using the residuals method was 15.4% in older men and 22.3% in older women. In addition, using two s.d. of SMI, the prevalence of sarcopenia and SO was 5.1% and 5.1%, respectively, in older men and 14.2% and 12.5%, respectively, in older women. Among women, SO subjects defined by the SMI had three times the risk of metabolic syndrome (odds ratios (OR)=3.24, 95% confidence interval (CI)=1.21-8.66) and non-sarcopenic obese subjects had approximately twice the risk of metabolic syndrome (OR=2.17, 95% CI=1.22-3.88) compared with normal subjects. Similar trends were observed in men. Conclusion: The prevalence and cutoff values of sarcopenia and SO in the Korean population were evaluated using different methods. Among the different indices of sarcopenia and SO, SO only defined using the SMI was associated with the risk of metabolic syndrome. As the Korean population gets older and more obese, the problematics of SO need to be elucidate.
We report a search result for a light sterile neutrino oscillation with roughly 2200 live days of data in the RENO experiment. The search is performed by electron antineutrino (νe) disappearance ...taking place between six 2.8 GW th reactors and two identical detectors located at 294 m (near) and 1383 m (far) from the center of the reactor array. A spectral comparison between near and far detectors can explore reactor νe oscillations to a light sterile neutrino. An observed spectral difference is found to be consistent with that of the three-flavor oscillation model. This yields limits on sin 22θ14 in the 10−4 ≲ | Δm412 | ≲ 0.5 eV2 region, free from reactor νe flux and spectrum uncertainties. The RENO result provides the most stringent limits on sterile neutrino mixing at | Δm412 | ≲ 0.002 eV2 using the νe disappearance channel.
Two borane-functionalized bidentate phosphine ligands that vary in tether length have been prepared to examine cooperative metal–substrate interactions. Ni(0) complexes react with aryl azides at low ...temperatures to form structurally unusual κ2-(N,N)-N3Ar adducts. Warming these adducts affords products of N2 extrusion and in one case, a Ni-imido compound that is capped by the appended borane. Reactions with 1-azidoadamantane (AdN3) provide a distinct outcome, where a proposed nickel imido intermediate activates the sp2 C–H bonds of arenes, even in the presence of benzylic C–H sites. Combined experimental and computational mechanistic studies demonstrate that the unique reactivity is a consequence of Lewis-acid-induced polarization of the Ni–NR bond, potentially providing a synthetic strategy for chemoselective reaction engineering.
The use of manganese in homogeneous hydrogenation catalysis has been a recent focus in the pursuit of more environmentally benign base metal catalysts. It has great promise with its unique reactivity ...when coupled with metal-ligand cooperation of aminophosphine pincer ligands. Here, a manganese precatalyst Mn(P-N-P′)(CO)
2
, where P-N-P′ is the amido form of the ligand (
S
,
S
)-PPh
2
CHPhCHPhNHCH
2
CH
2
P
i
Pr
2
, has been synthesized and used for base-free ketone hydrogenation. This catalyst shows exceptionally high enantioselectivity and good activity, with tolerance for base-sensitive substrates. NMR structural analysis of intermediates formed by the reaction of the amido complex with hydrogen under pressure identified a reactive hydride with an NOE contact with the
syn
amine proton. Computational analysis of the catalytic cycle reveals that the heterolytic splitting of dihydrogen across the MnN bond in the amido complex has a low barrier while the hydride transfer to the ketone is the turnover-limiting step. The pro-
S
transition state is found to be usually much lower in energy than the pro-
R
transition state depending on the ketone structure, consistent with the high (
S
) enantiomeric excess in the alcohol products. The energy to reach the transition state is higher for the distortion of the in-coming ketone than that of the hydride complex. In a one-to-one comparison with the similar iron catalyst FeH
2
(CO)(P-NH-P′), the manganese catalyst is found to have higher enantioselectivity, often over 95% ee, while the iron catalyst has higher activity and productivity. An explanation of these differences is provided on the basis of the more deformable iron hydride complex due to the smaller hydride ligands.
Base-free direct hydrogenation of ketones using a Mn(PNP′)(CO)
2
complex is more enantioselective than that of a related base-activated iron complex.
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