Organocatalytic synthesis of axially chiral tetrasubstituted allenes.

Asymmetric organocatalysis is a growing method for the synthesis of axially chiral tetrasubstituted allenes, the most challenging one among allene syntheses. In this method, chiral organocatalysts such as phase-transfer catalysts, peptides, disulfonimides, and binaphthyl/bispiro phosphoric acids have displayed remote control of regio- and stereoselectivity. Highly functionalized enantiopure allenes including those with an adjacent tertiary or quaternary stereocenter have been efficiently prepared with high levels of regio-, diastereo-, and enantioselectivity using this method. Several mechanistic pathways, including electrophilic addition to cumulenolate or zwitterionic enolate intermediates, alkynylogous Mukaiyama aldol reaction, nucleophilic addition to quinone methides, and dearomative addition to imino esters, were proposed. The method is necessary for providing access to axially chiral tetrasubstituted allenes, which can be utilized for the preparation of novel ligands, natural products, and organic materials, particularly those having complex structures. This review covers the enantioselective organocatalytic synthesis of these tetrasubstituted allenes and the mechanistic insights into the formation of the chiral axis up to July 2022.

Traceless point-to-axial chirality exchange in the atropselective synthesis of biaryls/heterobiaryls.

Traceless point-to-axial chirality exchange is a growing method for the preparation of axially chiral biaryls/heterobiaryls. During the exchange, stereogenic centers are destroyed and a chiral axis is simultaneously created. Highly functionalized enantiopure biaryls/heterobiaryls including those containing furanyl, thiophenyl, or pyrrolyl moieties with low rotation barriers have been prepared using this strategy with high levels of chirality transfer. The method is necessary for providing access to novel ligands, catalysts, natural products and active drugs having chiral axes. This review focuses on the chirality exchange approach for the formation of axially chiral biaryls/heterobiaryls and stereochemical models for the control of atropselectivity up to April 2019.

Progression of Amplitude-Integrated Electroencephalography and Neurological Outcomes in Neonates With Hypoxic-Ischemic Encephalopathy: A Single-Institution Cohort Study in Vietnam.

Background The characteristics of amplitude-integrated electroencephalography (aEEG) are associated with neurological outcomes in neonates with hypoxic-ischemic encephalopathy (HIE). We perform a longitudinal analysis of continuous monitoring of aEEG during therapeutic hypothermia and explore the association between aEEG interpretation and clinical neurological outcomes. Method We conducted a prospective cohort study on HIE neonates undergoing hypothermia with aEEG monitoring. Results A total of 37 HIE infants underwent hypothermia with improved aEEG background activity in 28 (75.7%) neonates, of which 18 (48.6%) neonates had background activity returned to a continuous pattern, and the median recovery time was 26.5 hours. Sleep-wake cycle (SWC) appeared in 14 (37.8%) cases, with a median onset time of 34.5 hours. Seizure activity on aEEG was present in 26 (70.3%) infants. Factors associated with poor outcomes at discharge included low voltage or flat trace background activity, a lack of improvement in background activity after hypothermia, and the absence of SWC. Neonates who took longer than 62 hours to return to continuous background activity (time to normal trace) or did not have SWC before the end of hypothermia were more likely to have unfavorable outcomes at discharge. Conclusions Longitudinal analysis of aEEG during hypothermia should be implemented in neonatal care units. The progression of these features on aEEG may predict neurological outcomes for HIE neonates.

Cardiac Tamponade Due to Pericardial Effusion Following Peripherally Inserted Central Catheter: A Single-Institution Case Series.

INTRODUCTION: Although the use of peripherally inserted central catheters (PICCs) has many advantages, misplacement can lead to serious life-threatening complications such as pericardial effusion (PCE) and cardiac tamponade (CT). This report aims to describe four cases of CT resulting from misplaced PICC, which were successfully managed. METHODS: Retrospective analysis of neonates who required PICC insertion and had PCE leading to CT in the Neonatal Intensive Care Unit (NICU) at The Children's Hospital 2, Ho Chi Minh City, Vietnam, during the year 2022. RESULTS: Four cases involved preterm infants at 28-30 weeks gestational age, weighing between 900-1,500 grams. The PCE/CT developed between 3 and 24 days following PICC insertion. The abrupt onset with clinical manifestations that showed hemodynamic instability included sudden deterioration, lethargy, apnea, bradycardia, pale skin, and cardiovascular collapse. We use cardiac point of care ultrasound (POCUS) to assess the condition of these patients and guide the pericardiocentesis procedure. The analysis of the aspirated fluid used for PCE/CT treatment is consistent with the component of parenteral nutrition. No deaths were encountered. CONCLUSION: Neonates presenting sudden deterioration following PICC insertion should undergo POCUS to prompt identifying PCE/CT. Timely diagnosis via POCUS, prompt pericardiocentesis, and prevention of misplaced PICC-associated serious complications are crucial. Monitoring of the PICC position twice a week is recommended to avoid life-threatening complications. Additionally, incorporating POCUS for identifying the tip of PICC rather than relying solely on X-ray should be considered in the current protocol.

DFT approach towards accurate prediction of 1H/13C NMR chemical shifts for dipterocarpol oxime.

A computational NMR approach for accurate predicting the 1H/13C chemical shifts of triterpenoid oximes featuring the screening of 144 DFT methods was demonstrated. Efficiently synthesized dipterocarpol oxime was employed as a model compound. The six highest accurate methods from the screening generated root-mean-square-error (RMSE) values in the range of 0.84 ppm (0.55%) to 1.14 ppm (0.75%) for calculated 13C shifts. For 1H results, simple, economical 6-31G basis set unexpectedly outperformed other more expensive basic sets; and the couple of it with selected functionals provided high accuracy shifts (0.0617 ppm (1.49%) ≤ RMSE ≤ 0.0870 ppm (2.04%)). These computational results strongly supported the proton and carbon assignments of the oxime including the difficult ones of diastereotopic methyl groups, the methyl groups attached to an internal olefin, and diastereotopic α-protons.

1H/13C chemical shift calculations for biaryls: DFT approaches to geometry optimization.

Twelve common density functional methods and seven basis sets for geometry optimization were evaluated on the accuracy of 1H/13C NMR chemical shift calculations for biaryls. For these functionals, 1H shifts calculations for gas phase optimized geometries were significantly less accurate than those for in-solution optimized structures, while 13C results were not strongly influenced by geometry optimization methods and solvent effects. B3LYP, B3PW91, mPW1PW91 and ωB97XD were the best-performing functionals with lowest errors; among seven basis sets, DGDZVP2 and 6-31G(d,p) outperformed the others. The combination of these functionals and basis sets resulted in high accuracy with CMAEmin = 0.0327 ppm (0.76%) and 0.888 ppm (0.58%) for 1H and 13C, respectively. The selected functionals and basis set were validated when consistently producing optimized structures with high accuracy results for 1H and 13C chemical shift calculations of two other biaryls. This study highly recommends the IEFPCM/B3LYP, B3PW91, mPW1PW91 or ωB97XD/DGDZVP2 or 6-31G(d,p) level of theory for the geometry optimization step, especially the solvent incorporation, which would lead to high accuracy 1H/13C calculation. This work would assist in the fully structural assignments of biaryls and provide insights into in-solution biaryl conformations.

Diastereoselective addition of Grignard reagents to α-epoxy N-sulfonyl hydrazones.

The α-alkylation of ketones and their derivatives by the addition of their corresponding enolates to alkyl halides is a fundamental synthetic transformation, but its utility is limited because the key bond-forming step proceeds in a bimolecular nucleophilic substitution fashion. Here we describe how an umpolung strategy that involves the addition of Grignard reagents to α-epoxy N-sulfonyl hydrazones-directed by the alkoxide of the 1-azo-3-alkoxy propenes formed in situ via base-induced ring opening of the epoxide-leads to the syn-selective production of α-alkyl-ß-hydroxy N-sulfonyl hydrazones with α-quaternary centres. This transformation is remarkable in its ability to incorporate an unprecedented range of carbon-based substituents, which include primary, secondary and tertiary alkyl, as well as alkenyl, aryl, allenyl and alkynyl groups. Subsequent hydrolysis of the ß-hydroxy N-sulfonyl hydrazone products produces the corresponding ß-hydroxy ketones. In addition to hydrolysis, the hydrazone products are poised to undergo numerous different known synthetic transformations via well-established chemistry, which would provide access to a wide array of useful structures.

Longitudinal Analyses of Presenteeism and Its Role as a Predictor of Sick Leave in Patients With Ankylosing Spondylitis.

OBJECTIVE: To investigate, in a cohort of patients with ankylosing spondylitis (AS) adequately treated with infliximab, changes over time in presenteeism and the role of presenteeism relative to that of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Bath Ankylosing Spondylitis Functional Index (BASFI) in predicting sick leave. METHODS: Data were analyzed from 71 patients with paid work and taking a stable dose of infliximab participating in a 96-week study with 5 assessment points. Covariates included presenteeism, sick leave, time, sex, age, BASDAI, BASFI, Bath Ankylosing Spondylitis Metrology Index, and part- or full-time work. Presenteeism represented the AS impact on productivity (by visual analog scale, range 0-10, where 10 = completely unproductive). Sick leave represented the number of days absent from work due to AS in the last 6 months. A linear mixed-effects model for presenteeism, and hurdle and zero-inflated count models for sick leave were explored. RESULTS: Mean ± SD presenteeism ranged from 2.2 ± 2.2 to 3.8 ± 7.8, and sick leave occurred in 8-17% of the patients during the 6-month period. Presenteeism positively correlated with BASDAI and BASFI, but was not significantly influenced by time. The chance of incurring sick leave was affected by presenteeism but not by BASDAI and BASFI. Conditional on being absent from work, the effect of presenteeism on the length of sick leave (in days) was much stronger than BASDAI and BASFI. For presenteeism ≥5, an increase of 1 unit in presenteeism yielded an increase by 36-40% (or 2-12 days) in the length of sick leave during the following 6 months. CONCLUSION: Presenteeism, even measured by a simple visual analog scale, was an important factor to explain future sick leave.

Accelerated axon loss in MOG35-55 experimental autoimmune encephalomyelitis (EAE) in myelin-associated glycoprotein-deficient (MAGKO) mice.

Myelin-associated glycoprotein (MAG) expressed by oligodendrocytes promotes the stability of axons but also impedes neural repair by inhibiting axon extension through lesioned white matter. We previously reported exacerbated axon losses in MAGKO as compared to wild type mice, 30days into experimental autoimmune encephalitis (EAE). Here, we report the time course of axon losses in EAE and show this occurs as early as 7days post-immunization, confirming MAG is protective against immune-mediated axon transection events. MAGKO mice also exhibit increased microglial activation prior to EAE, which is not seen in B4galnt1KO mice that also have axon loss, suggesting that the microglial activation may be a consequence of the loss of MAG inhibitory influence, and not a simple result of axonal degeneration.