Enantioselective Synthesis of Planar-Chiral Sulfur-Containing Cyclophanes by Chiral Sulfide Catalyzed Electrophilic Sulfenylation of Arenes.

An efficient catalytic asymmetric electrophilic sulfenylation reaction for the synthesis of planar-chiral sulfur-containing cyclophanes has been developed for the first time. This was achieved by using a new Lewis base catalyst and a new ortho-trifluoromethyl-substituted sulfenylating reagent. Using the substrates with low rotational energy barrier, the transformation proceeded through a dynamic kinetic resolution, and the high rotational energy barrier of the substrates allowed the reaction to undergo a kinetic resolution process. Meanwhile, this transformation was compatible with a desymmetrization process when the symmetric substrates were used. Various planar-chiral sulfur-containing cyclophanes were readily obtained in moderate to excellent yields with moderate to excellent enantioselectivities (up to 97 % yield and 95 % ee). This approach was used to synthesize pharmaceutically relevant planar-chiral sulfur-containing molecules. Density functional theory calculations showed that π-π interactions between the sulfenyl group and the aromatic ring in the substrate play a crucial role in enantioinduction in this sulfenylation reaction.

[Material basis and mechanism of Curcuma longa tuberous roots with and without vinegar processing in treating primary dysmenorrhea].

Liquid chromatography-mass spectrometry was employed to analyze the chemical components in Curcuma longa tuberous roots(HSYJ), C. longa tuberous roots processed with vinegar(CHSYJ), and rat serum after the administration. The active components of HSYJ and CHSYJ absorbed in serum were identified based on the secondary spectrum of database and literature. The targets of primary dysmenorrhea was screened out from database. The protein-protein interaction network analysis, gene ontology(GO) functional annotation, and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment analysis were performed for the common targets shared by the drug active components in serum and primary dysmenorrhea, and the component-target-pathway network was constructed. AutoDock was used to conduct molecular docking between the core components and targets. A total of 44 chemical components were identified from HSYJ and CHSYJ, including 18 absorbed in serum. On the basis of network pharmacology, we identified 8 core components(including procurcumenol, isobutyl p-hydroxybenzoate, ferulic acid, and zedoarondiol) and 10 core targets \[including interleukin-6(IL-6), estrogen receptor 1(ESR1), and prostaglandin-endoperoxide synthase 2(PTGS2)\]. The core targets were mainly distributed in the heart, liver, uterus, and smooth muscle. The molecular docking results showed that the core components were well bound to the core targets, indicating that HSYJ and CHSYJ may exert therapeutic effect on primary dysmenorrhea via estrogen, ovarian steroidogenesis, tumor necrosis factor(TNF), hypoxia-inducible factor-1(HIF-1), IL-17 and other signaling pathways. This study clarifies the HSYJ and CHSYJ components absorbed in serum, as well as the corresponding mechanism, providing a reference for further elucidating the therapeutic material basis and clinical application of HSYJ and CHSYJ.

[Effect of processing with vinegar on efficacy of Curcuma longa in treatment of dysmenorrhea in rats with syndrome of liver depression and Qi stagnation].

This study compared the effects of Curcuma longa before and after processing with vinegar on the rat model of dysmenorrhea with the syndrome of liver depression and Qi stagnation to reveal the mechanism of vinegar processing in improving the role of C. longa in soothing liver and relieving pain. The rat model of dysmenorrhea with the syndrome of liver depression and Qi stagnation was established according to the Preparation of the Animal Model of Dysmenorrhea(Draft) and the chronic unpredictable stress me-thod. The changes in the body weight, organ indexes, writhing latency, writhing score, and serum levels of six liver function indicators, sex hormones, pain factors, and blood rheological indicators were measured to evaluate the efficacy of C. longa processed with vinegar or not in treating dysmenorrhea in the rats with syndrome of liver depression and qi stagnation. Compared with the model group, the C. longa group(processed with vinegar or not) showed slow weight loss, increase in writhing latency, and decrease in writhing response(P<0.05). The inhibition rates on writhing in raw C. longa, vinegar-processed C. longa, and positive groups were 33.780%, 64.611%, and 62.466%, respectively. The significantly higher inhibition rate of the vinegar processing group indicated that vinegar-processed C. longa demonstrated more significant therapeutic effect. The vinegar-processed C. longa group showed lower levels of alanine aminotransferase(ALT), alkaline phosphatase(ALP), aspartate aminotransferase(AST), direct bilirubin(DBIL), and total bilirubin(TBIL) and higher level of albumin(ALB)(P<0.05), which indicated that vinegar processing enhanced the therapeutic effect of C. longa on liver injury. The serum levels of estradiol(E_2) and oxytocin(OT) were lower in the vinegar-processed C. longa group(P<0.05), indicating that the vinegar-processed C. longa could regulate the sex hormone levels, reduce the activity of uterine smooth muscle and contraction of uterus, and alleviate the symptoms of dysmenorrhea in rats. Moreover, the vinegar-processed C. longa group showed lower interleukin-6(IL-6) and arginine vasopressin(AVP) levels and higher beta-endorphin(ß-EP) level(P<0.05), which indicated that vinegar-processed C. longa regulated the levels of pain factors to exert the pain-relieving effect. Drug intervention decreased the whole blood viscosity low-cut, medium-cut and high-cut values, plasma viscosity, whole blood reduction viscosity low-cut and high-cut values, erythrocyte cumulative pressure, and equation K value of erythrocyte sedimentation rate(P<0.05), and the vinegar-processed C. longa group outperformed other groups. This result indicated that vinegar processing enhanced the function of C. longa in improving the local blood rheology. C. longa processed with vinegar can enter the liver to relieve the da-mage to the heart, liver, kidney, and uterus, repair the liver function, and recover the sex hormone levels and immune function by regulating the levels of sex hormones and pain factors and improving the blood rheology. It activates the pain-relieving mechanism to relieve the pain, protect the liver, and fight inflammation, which is consistent with the theory that vinegar processing facilitates C. longa entering the liver to sooth liver and relieve pain.

Chiral Selenide/Achiral Sulfonic Acid Cocatalyzed Atroposelective Sulfenylation of Biaryl Phenols via a Desymmetrization/Kinetic Resolution Sequence.

Enantioselective synthesis of axially chiral sulfur-containing biaryl derivatives through the electrophilic sulfenylation of biaryl phenols has been achieved for the first time. This catalytic asymmetric system, which involves sequential desymmetrization and kinetic resolution, is enabled by a combination of a novel 3,3'-disubstituted BINOL-derived selenide catalyst and an achiral sulfonic acid. Control experiments and computational studies suggest that multiple noncovalent interactions between the cocatalysts and substrate, especially a network of hydrogen bond interactions, play a crucial role in determining the enantioselectivity and reactivity.

Tenofovir Alafenamide for Pregnant Chinese Women With Active Chronic Hepatitis B: A Multicenter Prospective Study.

BACKGROUND & AIMS: Data on long-term tenofovir alafenamide (TAF) therapy for pregnant women with active chronic hepatitis B (CHB) (immune clearance and reactivation phases, currently and previously diagnosed) and their infants are lacking. METHODS: Pregnant women with active CHB treated with TAF and tenofovir disoproxil fumarate (TDF) were enrolled in this multicenter prospective study, and infants received immunoprophylaxis. The primary outcomes were rates of adverse (safety) events in pregnant women and defects in infants and fetuses. The secondary outcomes were virologic responses in pregnant women, infants' safety, hepatitis B surface antigen (HBsAg) status, and growth conditions. RESULTS: One hundred three and 104 pregnant women were enrolled and 102 and 104 infants were born in the TAF and TDF groups, respectively. In the TAF group, the mean age, gestational age, alanine aminotransferase level, and viral loads at treatment initiation were 29.3 years, 1.3 weeks, 122.2 U/L, and 5.1 log10 IU/mL, respectively. TAF was well-tolerated, and the most common adverse event was nausea (29.1%) during a mean of 2 years of treatment. Notably, 1 (1.0%) TAF-treated pregnant woman underwent induced abortion due to noncausal fetal cleft lip and palate. No infants in either group had birth defects. In the TAF group, the hepatitis B e antigen seroconversion rate was 20.7% at postpartum month 6, infants had normal growth parameters, and no infants were positive for HBsAg at 7 months. The TDF group had comparable safety and effectiveness profiles. CONCLUSIONS: TAF administered throughout or beginning in early pregnancy is generally safe and effective for pregnant women with active CHB and their infants.

Real-Time Tunable Dynamic Range for Calibration-Free Biomolecular Measurements with a Temperature-Modulated Electrochemical Aptamer-Based Sensor in an Unprocessed Actual Sample.

The sensing technologies for monitoring molecular analytes in biological fluids with high frequency and in real time could enable a broad range of applications in personalized healthcare and clinical diagnosis. However, due to the limited dynamic range (less than 81-fold), real-time analysis of biomolecular concentration varying over multiple orders of magnitude is a severe challenge faced by this class of analytical platforms. For the first time, we describe here that temperature-modulated electrochemical aptamer-based sensors with a dynamically adjustable calibration-free detection window could enable continuous, real-time, and accurate response for the several-hundredfold target concentration changes in unprocessed actual samples. Specifically, we could regulate the electrode surface temperature of sensors to obtain the corresponding dynamic range because of the temperature-dependent affinity variations. This temperature modulation method relies on an alternate hot and cold electrode reported by our group, whose surface could actively be heated and cooled without the need for altering ambient temperature, thus likewise applying for the flowing system. We then performed dual-frequency calibration-free measurements at different interface temperatures, thus achieving an extended detection window from 25 to 2500 µM for procaine in undiluted urine, 1-500 µM for adenosine triphosphate, and 5-2000 µM for adenosine in undiluted serum. The resulting sensor architecture could drastically expand the real-time response range accessible to these continuous, reagent-less biosensors.

Sofosbuvir-based therapy for late pregnant women and infants with severe chronic hepatitis C: A case series study.

Data on sofosbuvir-based therapy for pregnant women and infants with severe chronic hepatitis C (CHC) are lacking. Two late pregnant women and one female infant with severe CHC were enrolled for treatment. Pregnant Women 1 and 2 and Infant 3 were 30, 33, and 1.2 years old, respectively; the gestational ages of pregnant Women 1 and 2 were 31 and 26 weeks, respectively. Notably, pregnant Women 1 and 2 and Infant 3 had hepatitis C virus (HCV) RNA levels of 139 000, 198 000, and 8 450 000 IU/ml; alanine aminotransferase levels of 420, 781, and 220 U/L; and received sofosbuvir/ledipasvir, sofosbuvir/velpatasvir, and sofosbuvir/ledipasvir for 12 weeks, respectively. All three patients were safely cured with favorable tolerance, and two newborns were both breastfeeding and were consistently negative for the anti-HCV antibody during the 1-year follow-up after birth. Additionally, two newborns and Infant 3 had normal growth parameters during the follow-up year one. In conclusion, this case series study found that sofosbuvir-based therapy for pregnant women and infants with severe CHC is safe and effective. The data may fill the gap and provide evidence of the use of sofosbuvir-based therapy as a reference when similar severe CHC situations are encountered during clinical practice.

The Alkynylative Difunctionalization of Alkenes.

Given alkynyl group is an important functional unit, a variety of efficient methods have been developed to construct alkynyl-containing compounds. Among them, the alkynylative difunctionalization of alkenes is one of the most straightforward and efficient strategies for preparing these compounds and so has made great progress in recent years, including the catalytic asymmetric manner. However, there is no comprehensive review to summarize these studies. This review is aimed at comprehensively summarizing the alkynylative difunctionalization of alkenes, which is presented in terms of alkynylation-initiated and alkynylation-terminated difunctionalizations of alkenes. We hope that this review will help to encourage more researchers to further explore in this field.

[The Association between the Level of Plasma D-dimer and Disease Severity and Prognosis of Mycoplasma pneumoniae Pneumonia in Children].

OBJECTIVE: To explore the association between the levels of plasma D-dimer and the disease severity and prognosis of Mycoplasma pneumoniae pneumonia (MPP) in children. METHODS: We retrospectively analyzed the clinical data of pediatric MPP patients who were admitted in our hospital between January 1, 2016 and December 31, 2018. According to the peak value of D-dimer, patients were divided into the normal group (D-dimer<0.55 mg/L) and the elevated group (D-dimer≥0.55 mg/L). Information regarding the demographics, clinical manifestations, auxiliary examinations and treatments of patients in the two groups was compared. RESULTS: Of the 231 MPP patients included in the study, 70 were in the normal group and 161 were in the elevated group. The age of patients in the D-dimer elevated group was significantly higher than that of the normal group ( P<0.01). Compared with the normal group, the elevated group had longer lengths of fever, hospital stay and antibiotic therapy, and more severe radiographic manifestations (all P<0.01). In addition, the incidence of extrapulmonary complications, refractory MPP and severe MPP in the elevated group were significantly higher than those in the normal group ( P<0.01). As for the laboratory data, we found that neutrophils, C-reactive protein, lactate dehydrogenase, interleukin-6, interleukin-10 and interferon-γ were significantly higher in the elevated group than those in the normal group ( P<0.05). After treatments, all patients showed improvement and were discharged, but the proportions of patients requiring glucocorticoids, bronchoscopy, thoracentesis were significantly higher in the elevated group than those in the normal group ( P<0.05). Follow-up findings showed that the absorption rate of lung lesions 4 weeks after admission was significantly higher, the time needed for lung lesions absorption was significantly shorter, and the incidence of pulmonary sequelae was significantly lower in the normal group than those in the elevated group (all P<0.05). Correlation analysis showed that D-dimer level was positively correlated with the severity of pneumonia ( r=0.272, P=0.000) and the incidence of pulmonary sequelae ( r=0.235, P=0.000). CONCLUSION: Pediatric patients of MPP who had elevated plasma D-dimer had clinical manifestations that were more severe, required longer duration of treatment and longer recovery time for lung lesions, and were more likely to have pulmonary sequelae.

Atroposelective Electrophilic Sulfenylation of N-Aryl Aminoquinone Derivatives Catalyzed by Chiral SPINOL-Derived Sulfide.

Atroposelective electrophilic sulfenylation of N-aryl aminoquinone derivatives has been achieved for the first time. This transformation is enabled by a new chiral 6,6'-disubstituted SPINOL-derived sulfide catalyst, which was first synthesized and then successfully explored for catalyzing enantioselective reactions. Various axially chiral sulfur-containing diarylamine derivatives were readily obtained in moderate to excellent yields with moderate to excellent enantioselectivities. A class of relatively flexible stereogenic C-N axes was easily constructed. The experimental results and a computational study suggested that an intramolecular N-H⋅⋅⋅S hydrogen bond is important for the stability of the C-N axis, which is consistent with our hypothesis. Density functional theory calculations revealed the origin of atroposelectivity and underscored the importance of catalyst rigidity in this sulfenylation reaction.

Tenofovir Alafenamide to Prevent Perinatal Hepatitis B Transmission: A Multicenter, Prospective, Observational Study.

BACKGROUND: Few safety and effectiveness results have been published regarding the administration of tenofovir alafenamide fumarate (TAF) during pregnancy for the prevention of mother-to-child transmission (MTCT) of hepatitis B virus (HBV). METHODS: In this multicenter prospective observational study, pregnant women with HBV DNA levels higher than 200 000 IU/mL who received TAF or tenofovir disoproxil fumarate (TDF) from gestational weeks 24-35 to delivery were 1:1 enrolled and followed until postpartum month 6. Infants received immunoprophylaxis. The primary endpoint was the safety of mothers and infants. The secondary endpoint was the hepatitis B surface antigen (HBsAg)-positive rate at 7 months for infants. RESULTS: In total, 116 and 116 mothers were enrolled, and 117 and 116 infants were born, in the TAF and TDF groups, respectively. TAF was well tolerated during a mean treatment duration of 11.0 weeks. The most common maternal adverse event was nausea (19.0%). One (0.9%), 3 (2.6%), and 9 (7.8%) mothers had abnormal alanine aminotransferase levels at delivery and at postpartum months 3 and 6, respectively. The TDF group had safety profiles that were comparable to those of the TAF group. No infants had birth defects in either group. The infants' physical and neurological development at birth and at 7 months in the TAF group were comparable with those in the TDF group. The HBsAg positive rate was 0% at 7 months in all 233 infants. CONCLUSIONS: Antiviral prophylaxis with TAF was determined to be generally safe for both mothers and infants and reduced the MTCT rate to 0%.

Temperature-Alternated Electrochemical Aptamer-Based Biosensor for Calibration-Free and Sensitive Molecular Measurements in an Unprocessed Actual Sample.

Frequently calibrating electrochemical biosensors (ECBs) to obtain acceptable accuracy can be cumbersome for the users. Thus, the achievement of calibration-free operation would effectively lead to commercial applications for ECBs in the real world. Herein, we fabricated a temperature-alternated electrochemical aptamer-based (TAEAB) sensor, producing a cycle of "enhanced-responsive and ∼nonresponsive" state at rapidly alternated interface temperatures (5 and 30 °C, respectively). The ratio of peak currents collected at two temperatures overcomes sensor-to-sensor fabrication variations, obviating sensor calibration prior to use due to its good reproducibility. We then demonstrated the capability of TAEAB sensors for improved, sensitive, and calibration-free measurement of different targets within 7 min, which respectively achieved a detection limit of 0.5 µM procaine in undiluted urine and 1.0 µM adenosine triphosphate in undiluted serum. This generalizable approach ameliorates sensitivity without the complicated amplification step, thus simplifying the operation procedure and reducing the detection time, which will effectively improve the clinical utility of biosensors.

[Study on effect of different processing methods on chemical components of Chuanxiong Rhizoma].

To determine the content of extracts in different processed products of Chuanxiong Rhizoma and the content of chlorogenic acid, ferulic acid, senkyunolide Ⅰ, coniferyl ferulate, senkyunolide A and ligustilide, in order to study the effect of different proces-sing methods on the alcohol-soluble extract and the content of six ingredients of Chuanxiong Rhizoma. The extract was determined according to the alcohol-soluble extract determination method set forth in item 2201 of the 2020 Chinese Pharmacopoeia Ⅳ; the content was determined by using Agilent TC-C_(18) column(4.6 mm×250 mm, 5 µm) for gradient elution, with acetonitrile(A)-0.5% acetic acid solution(B) as the mobile phase; the column temperature was at 30 ℃; the flow rate was 1.0 mL·min~(-1), the detection wavelength was 285 nm; and the injection volume was 10 µL. Compared with Chuanxiong Rhizoma, the extracts of processed products all increased significantly; by the degree of increase, the order was stir-frying Chuanxiong Rhizoma with honey>stir-frying Chuanxiong Rhizoma with rice wine>stir-frying Chuanxiong Rhizoma with Angelicae Dahuricae Radix decoction>stir-frying Chuanxiong Rhizoma with tea decoction; the HPLC method was convenient and reliable, with a high linear relationship of chlorogenic acid, ferulic acid, senkyunolide Ⅰ, coniferyl ferulate, senkyunolide A and ligustilide, and a high precision, repeatability, stability and the sample recovery rate in Chuanxiong Rhizoma and its processed products. There were 15 chromatographic peaks before and after processing, eight of them were identified. Compared with the pre-processing, two chromatographic peaks were added after the stir-frying with honey and rice wine; and four chromatographic peaks were added after the processing with Angelicae Dahuricae Radix decoction; the contents of chlorogenic acid, ferulic acid, senkyunolide Ⅰ, coniferyl ferulate, senkyunolide A, and ligustilide in stir-frying Chuanxiong Rhizoma with rice wine were all reduced. Except for the content of ferulic acid that increased, the content of the other five components decreased in stir-frying Chuanxiong Rhizoma with honey, stir-frying Chuanxiong Rhizoma with tea decoction, and stir-frying Chuanxiong Rhizoma with Angelicae Dahuricae Radix decoction. Rice wine, honey, decoction of tea and Angelicae Dahuricae Radix could all promote the dissolution of chemical components in Chuanxiong Rhizoma, and increase the content of extract; the changes in the contents of six components of different processed products could provide a certain basis for studying chemical composition and efficacy of different processed products of Chuanxiong Rhizoma.

Epidemiological features and viral shedding in children with SARS-CoV-2 infection.

A pandemic of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection broke out all over the world; however, epidemiological data and viral shedding in pediatric patients are limited. We conducted a retrospective, multicenter study, and followed-up with all children from the families with SARS-CoV-2 infected members in Zhejiang Province, China. All infections were confirmed by testing the SARS-CoV-2 RNA with real-time reverse transcription PCR method, and epidemiological data between children and adults in the same families were compared. Effect of antiviral therapy was evaluated observationally and fecal-viral excretion times among groups with different antiviral regiments were compared with Kaplan-Meier plot. By 29 February 2020, 1298 cases from 883 families were confirmed with SARS-CoV-2 infection and 314 of which were families with children. Incidence of infection in child close contacts was significantly lower than that in adult contacts (13.2% vs 21.2%). The mean age of 43 pediatric cases was 8.2 years and mean incubation period was 9.1 days. Forty (93.0%) were family clustering. Thirty-three children had coronavirus disease 2019 (20 pneumonia) with mild symptoms and 10 were asymptomatic. Fecal SARS-CoV-2 RNA detection was positive in 91.4% (32/35) cases and some children had viral excretion time over 70 days. Viral clearance time was not different among the groups treated with different antiviral regiments. No subsequent infection was observed in family contacts of fecal-viral-excreting children. Children have lower susceptibility of SARS-CoV-2 infection, longer incubation, and fecal-viral excretion time. Positive results of fecal SARS-CoV-2 RNA detection were not used as indication for hospitalization or quarantine.

Assessment of serum sialic acid correlated with C3 in children with Mycoplasma pneumoniae pneumonia.

BACKGROUND: Different from the diagnosis of bacterial infections, Mycoplasma pneumoniae pneumonia (MPP) is still lacking of convenient non-specific laboratory parameters. METHOD: A total of 125 children with MPP were included in the MPP group and 89 children with Mycoplasma-negative pneumonia were included in the control group, and the sera were collected from the children at both the acute and recovery stages in the two groups. RESULTS: The sialic acid and C3 in the MPP group were significantly higher than those in the control group both at the acute and at the recovery stage. On the other hand, the sialic acid and C3 at the acute stage were significantly higher than those at the recovery stage in the MPP group. However, in the control group, the sialic acid and C3 demonstrated IgG exhibited no significant change between the acute stage and the recovery stage. Lastly, positive correlations between sialic acid level and C3 level were identified in the MPP group at both acute and recovery stages. CONCLUSION: Our study demonstrated that the serum sialic acid correlated with C3 specifically increased in children with MPP, indicating that it might be the important non-specific parameters in the diagnosis of MPP.

Tolerance evaluation of Moringa oleifera extract to Hailan brown laying hens.

The aim of this experiment was to study the effects of dietary addition of high-dose Moringa extract (10 g/kg Moringa extract) on laying performance, haematological parameters, organ index and organ histopathology of Hailan brown laying hens in order to determine the safety limit of Moringa extract in laying hens diet. 270 Hailan brown commercial laying hens with similar body weight were randomly divided into three treatments, 6 replicates per treatment and 15 chickens per replicate. Corn-soybean meal-based diet was used in the experiment, and 0, 0.75 and 10 g/kg extracts of Moringa oleifera were added to the basic diet in the experimental group. The experiment lasted 24 weeks. The results showed that the treatment group given 10 g/kg of dietary Moringa extract had no significant difference in egg-laying performance from the control group (p > .05). Adding 0.75 g/kg Moringa extract had no significant effect on the production performance during the early stage of the experiment (p > .05), but during the later stage, F/E was significantly lower than in the control group (p < .05), and no significantly difference compared with 10 g/kg treatment group (p > .05). The addition of Moringa oleifera extract had no significant effect on serum biochemical indices of laying hens except ALB and UREA (p > .05). The addition of Moringa oleifera extract had no significant effect on blood routine indexes of laying hens except for PLT, MON and HCT (p > .05). The digestive and immune organ indexes of laying hens at the later stage of the experiment (24 weeks) were not significantly affected by the addition of Moringa extract (p > .05) except ceca. There were no obvious abnormalities in histological structure. On the whole, we find it is safe to add Moringa oleifera extract to the diet of laying hens at a dosage of less than 10 g/kg.

[Emergency plan for inter-hospital transfer of newborns with SARS-CoV-2 infection].

Since December 2019, the outbreak of coronavirus disease (COVID-19) has become the most serious public health issue. As the special population with immature immune function, newborns with COVID-19 have been reported. Newborns with suspected or confirmed COVID-19 should be transferred to designated hospitals for isolation treatment. An emergency transfer response plan for newborns with COVID-19 has been worked out. This plan puts forward the indications for neonatal COVID-19 transfer, organization management, protection strategies for medical staff, work procedures, and disinfection methods for transfer equipment, in order to provide guidance and suggestions for the inter-hospital transfer of suspected or confirmed neonatal COVID-19.

Lewis Base/Brønsted Acid Co-Catalyzed Asymmetric Thiolation of Alkenes with Acid-Controlled Divergent Regioselectivity.

A divergent strategy for the facile preparation of various enantioenriched phenylthio-substituted lactones was developed based on Lewis base/Brønsted acid co-catalyzed thiolation of homoallylic acids. The acid-controlled regiodivergent cyclization (6-endo vs. 5-exo) and acid-mediated stereoselective rearrangement of phenylthio-substituted lactones were explored. Experimental and computational studies were performed to clarify the origins of the regioselectivity and enantioselectivity. The calculation results suggest that C-O and C-S bond formation might occur simultaneously, without formation of a commonly supposed catalyst-coordinated thiiranium ion intermediate and the potential π-π stacking between substrate and SPh as an important factor in the enantio-determining step. Finally, this methodology was applied in the rapid syntheses of the bioactive natural products (+)-ricciocarpin A and (R)-dodecan-4-olide.

Copper-Complex-Catalyzed Asymmetric Aerobic Oxidative Cross-Coupling of 2-Naphthols: Enantioselective Synthesis of 3,3'-Substituted C1 -Symmetric BINOLs.

A novel chiral 1,5-N,N-bidentate ligand based on a spirocyclic pyrrolidine oxazoline backbone was designed and prepared, and it coordinates CuBr in situ to form an unprecedented catalyst that enables efficient oxidative cross-coupling of 2-naphthols. Air serves as an external oxidant and generates a series of C1 -symmetric chiral BINOL derivatives with high enantioselectivity (up to 99 % ee) and good yield (up to 87 %). This approach is tolerant of a broader substrates scope, particularly substrates bearing various 3- and 3'-substituents. A preliminary investigation using one of the obtained C1 -symmetric BINOL products was used as an organocatalyst, exhibiting better enantioselectivity than the previously reported organocatalyst, for the asymmetric α-alkylation of amino esters.

Lewis Base/Brønsted Acid Co-catalyzed Enantioselective Sulfenylation/Semipinacol Rearrangement of Di- and Trisubstituted Allylic Alcohols.

An enantioselective sulfenylation/semipinacol rearrangement of 1,1-disubstituted and trisubstituted allylic alcohols was accomplished with a chiral Lewis base and a chiral Brønsted acid as cocatalysts, generating various ß-arylthio ketones bearing an all-carbon quaternary center in moderate to excellent yields and excellent enantioselectivities. These chiral arylthio ketone products are common intermediates with many applications, for example, in the design of new chiral catalysts/ligands and the total synthesis of natural products. Computational studies (DFT calculations) were carried out to explain the enantioselectivity and the role of the chiral Brønsted acid. Additionally, the synthetic utility of this method was exemplified by an enantioselective total synthesis of (-)-herbertene and a one-pot synthesis of a chiral sulfoxide and sulfone.