Photoredox-catalyzed C(sp2)-H trifluoromethylation of 3-methylene-isoindolin-1-ones under metal-free conditions.

A facile synthetic method for direct C(sp2)-H bond trifluoromethylation of 3-methylene-isoindolin-1-ones under visible-light-induced metal-free conditions is presented. This protocol features mild reaction conditions, broad substrate scope and excellent functional group tolerance, resulting in a range of structurally diverse trifluoromethylated products in good to excellent yields.

The effect of salinity on trimethoprim adsorption by activated sludge extracellular polymeric substances at trace concentration.

The saline wastewater produced in industrial activities and seawater use would flow into wastewater treatment plants and affect the characteristic of extracellular polymeric substance (EPS) of activated sludge, which could potentially impact the removal of antibiotics via adsorption. Nonetheless, the effect of salinity on trimethoprim adsorption by activated sludge extracellular polymeric substances at trace concentration and the underlying mechanism remain largely unknown. In this study, the effect of salinity on the adsorption removal of a typical antibiotic, i.e., trimethoprim (TMP) at trace concentration (25.0 µg/L) was evaluated. The results showed the content of EPS was decreased significantly from 56.36 to 21.70 mg/g VSS when the salinity was increased from 0 to 10 g/L. Protein fractions occupied the predominant component of EPS, whose concentration was decreased from 38.17 to 12.83 mg/g VSS. The equilibrium adsorption capacity of activated sludge for TMP was decreased by 49.70% (from 4.97 to 2.50 µg/g VSS). The fluorescence quenching results indicated the fluorescence intensity of tryptophan-like substances was decreased by 30% and the adsorption sites of EPS were decreased from 0.51 to 0.21 when the salinity was increased. The infrared spectrum and XPS results showed that the nitrogen-containing groups from protein were decreased significantly. The circular dichroic analysis showed α helix structure of protein in EPS was decreased with the increase of salinity, which was responsible for the decrease of adsorption capacity for TMP.

Morphology-independent general-purpose optical surface tractor beam.

Optical tractor beams capable of pulling particles backward have garnered significant and increasing interest. Traditional optical tractor beams are limited to free space beams with small forward wavevectors, enabling them to pull selected particles. Here, we present a comprehensive theory for the optical force exerted by a surface wave using analytical and numerical calculations, revealing the relationship between the canonical momentum and optical forces. Based on this theory, we demonstrate a general purpose optical surface tractor beam that can pull any passive particle, regardless of size, composition, or geometry. The tractor beam utilizes a surface wave with negative canonical momentum characterized by a single well-defined negative Bloch k vector. The tractor beam relies on a mechanism where the negative incident force always surpasses the recoil force. As such, the tractor beam, when excited on the surface of a double-negative index metamaterial, can pull particles with different morphologies.

Coronary CT Angiography-Based Radiomics to Predict Vessel-Specific Ischemia by Stress Dynamic CT Myocardial Perfusion Imaging.

RATIONALE AND OBJECTIVES: To investigate the predictive value of coronary CT angiography (CCTA)-based radiomics for vessel-specific ischemia by stress dynamic CT myocardial perfusion imaging (MPI). MATERIALS AND METHODS: Patients with typical angina/atypical angina/non-angina chest pain who underwent both stress dynamic CT MPI and CCTA scans were retrospectively enrolled. The following models were constructed for ischemic prediction using logistic regression and CCTA-derived quantitative and radiomic features: plaque quantitative model, lumen quantitative model, CT-fractional flow reserve (CT-FFR) model, integrative quantitative model, plaque radiomic model, peri-coronary adipose tissue (pCAT) radiomic model, integrative radiomic model, and quantitative and radiomic fusion model. A relative myocardial blood flow ≤ 0.75 on stress dynamic CT MPI was considered ischemic. The models' performances were quantified by the area under the receiver-operating characteristic curve (AUC). RESULTS: 386 coronary vessels (stenosis grade: 25%∼75%; training set: 200 [ischemia/non-ischemia=96/104]; test set:186 [ischemia/non-ischemia=79/107]) from 326 patients were included. The plaque radiomic model (training/test set: AUC=0.81/0.80) outperformed (p < .05) both the plaque quantitative (training/test set: AUC=0.71/0.68) model and the lumen quantitative (training/test set: AUC=0.69/0.65) model in identifying ischemia. The integrative radiomic model (training/test set: AUC=0.83/0.82) outperformed (p < .05) the CT-FFR model (training/test set: AUC=0.74/0.73) for ischemic prediction. The quantitative and radiomic fusion model (training/test set: AUC=0.86/0.84) outperformed (p < .05) the integrative quantitative model (training/test set: AUC=0.79/0.77) for ischemic detection. CONCLUSION: The plaque and pCAT radiomic features were superior to the plaque and pCAT quantitative features in predicting ischemia and the addition of the radiomic features to the quantitative features for ischemic identification yielded incremental discriminatory value.

Synergism of Light-Induced [4 + 4] Cycloaddition and Electron Transfer Toward Switchable Photoluminescence and Single-Molecule Magnet Behavior in a Dy4 Cubane.

Molecular materials possessing switchable magneto-optical properties are of great interest due to their potential applications in spintronics and molecular devices. However, switching their photoluminescence (PL) and single-molecule magnet (SMM) behavior via light-induced structural changes still constitutes a formidable challenge. Here, a series of cubane structures were synthesized via self-assembly of 9-anthracene carboxylic acid (HAC) and rare-earth ions. All complexes exhibited obvious photochromic phenomena and complete PL quenching upon Xe lamp irradiation, which were realized via the synergistic effect of photogenerated radicals and [4 + 4] photocycloaddition of the AC components. The quenched PL showed the largest fluorescence intensity change (99.72%) in electron-transfer photochromic materials. A reversible decoloration process was realized via mechanical grinding, which is unexpectedly in the electron-transfer photochromic materials. Importantly, an SMM behavior of the Dy analog was observed after room-temperature irradiation due to the photocycloaddition of AC ligands and the photogenerated stable radicals changed the electrostatic ligand field and magnetic coupling. Moreover, based on the remarkably photochromic and photoluminescent properties of these compounds, 2 demos were applied to support their application in information anti-counterfeiting and inkless printing. This work, for the first time utilizing the simultaneous modulation of photocycloaddition and photogenerated radicals in one system, realizes complete PL quenching and light-induced SMM behavior, providing a dynamical switch for the construction of multifunctional polymorphic materials with optical response and optical storage devices.

Optimal Oxophilicity at the Fe-Nx Interface Enhances the Generation of Singlet Oxygen for Efficient Fenton-Like Catalysis.

In the pursuit of efficient singlet oxygen generation in Fenton-like catalysis, the utilization of single-atom catalysts (SACs) emerges as a highly desired strategy. Here, a discovery is reported that the single-atom Fe coordinated with five N-atoms on N-doped porous carbon, denoted as Fe-N5/NC, outperform its counterparts, those coordinated with four (Fe-N4/NC) or six N-atoms (Fe-N6/NC), as well as state-of-the-art SACs comprising other transition metals. Thus, Fe-N5/NC exhibits exceptional efficacy in activating peroxymonosulfate for the degradation of organic pollutants. The coordination number of N-atoms can be readily adjusted by pyrolysis of pre-assembly structures consisting of Fe3+ and various isomers of phenylenediamine. Fe-N5/NC displayed outstanding tolerance to environmental disturbances and minimal iron leaching when incorporated into a membrane reactor. A mechanistic study reveals that the axial ligand N reduces the contribution of Fe-3d orbitals in LUMO and increases the LUMO energy of Fe-N5/NC. This, in turn, reduces the oxophilicity of the Fe center, promoting the reactivity of *OO intermediate-a pivotal step for yielding singlet oxygen and the rate-determining step. These findings unveil the significance of manipulating the oxophilicity of metal atoms in single-atom catalysis and highlight the potential to augment Fenton-like catalysis performance using Fe-SACs.

A pair of E3 ubiquitin ligases control immunity and flowering by targeting different ELF3 proteins in rice.

The ubiquitin-proteasome system (UPS) plays crucial roles in cellular processes including plant growth, development, and stress responses. In this study, we report that a pair of E3 ubiquitin ligases, AvrPiz-t-interaction protein 6 (APIP6) and IPA1-interaction protein 1 (IPI1), intricately target early flowering3 (ELF3) paralogous proteins to control rice immunity and flowering. APIP6 forms homo-oligomers or hetero-oligomers with IPI1. Both proteins interact with OsELF3-2, promoting its degradation to positively control resistance against the rice blast fungus (Magnaporthe oryzae). Intriguingly, overexpression of IPI1 in Nipponbare caused significantly late-flowering phenotypes similar to the oself3-1 mutant. Except for late flowering, oself3-1 enhances resistance against M. oryzae. IPI1 also interacts with and promotes the degradation of OsELF3-1, a paralog of OsELF3-2. Notably, IPI1 and APIP6 synergistically modulate OsELF3s degradation, finely tuning blast disease resistance by targeting OsELF3-2, while IPI1 controls both disease resistance and flowering by targeting OsELF3-1. This study unravels multiple functions for a pair of E3 ligases in rice.

Half-Space Sound Field Reconstruction Based on the Combination of the Helmholtz Equation Least-Squares Method and Equivalent Source Method.

In practical conditions, near-field acoustic holography (NAH) requires the measurement environment to be a free sound field. If vibrating objects are located above the reflective ground, the sound field becomes non-free in the presence of a reflecting surface, and conventional NAH may not identify the sound source. In this work, two types of half-space NAH techniques based on the Helmholtz equation least-squares (HELS) method are developed to reconstruct the sound field above a reflecting plane. The techniques are devised by introducing the concept of equivalent source in HELS-method-based NAH. Two equivalent sources are tested. In one technique, spherical waves are used as the equivalent source, and the sound reflected from the reflecting surface is regarded as a linear superposition of orthogonal spherical wave functions of different orders located below the reflecting surface. In the other technique, some monopoles are considered equivalent sources, and the reflected sound is considered a series of sounds generated by simple sources distributed under the reflecting surface. The sound field is reconstructed by matching the pressure measured on the holographic surface with the orthogonal spherical wave source in the vibrating object and replacing the reflected sound with an equivalent source. Therefore, neither technique is related to the surface impedance of the reflected plane. Compared with the HELS method, both methods show higher reconstruction accuracy for a half-space sound field and are expected to broaden the application range of HELS-method-based NAH techniques.

Association between fluoride exposure and psychiatric disorders in adults.

To explore the association between fluoride exposure and depression / anxiety in adults, the 1,169 participants were recruited. The demographic information of participants was obtained through questionnaire survey and physical measurements. Morning urine samples were collected, and urinary fluoride (UF) level was determined. Changes in depression and anxiety levels were evaluated using the Patient Health Questionnaire-2 and General Anxiety Disorder-2 scales. The association between psychiatric disorders and UF levels was analyzed. In the total population, the prevalence of depression and anxiety were 3.17% and 4.19%, respectively. These results showed no significant association between depression / anxiety scale scores and UF levels. Logistic regression suggested no significant association between depression / anxiety levels, and UF levels, but there was an interaction between UF and income on depression. Our findings highlighted the interaction between fluoride exposure and monthly income, which may affect depression in adults.

Near-Full-Spectrum Emission Realized in a Single Lead Halide Perovskite across the Visible-Light Region.

The engineering of tunable photoluminescence (PL) in single materials with a full-spectrum emission represents a highly coveted objective but poses a formidable challenge. In this context, the realization of near-full-spectrum PL emission, spanning the visible light range from 424 to 620 nm, in a single-component two-dimensional (2D) hybrid lead halide perovskite, (ETA)2PbBr4 (ETA+ = (HO)(CH2)2NH3+), is reported, achieved through high-pressure treatment. A pressure-induced phase transition occurs upon compression, transforming the crystal structure from an orthorhombic phase under ambient conditions to a monoclinic structure at high pressure. This phase transition driven by the adaptive and dynamic configuration changes of organic amine cations enables an effective and continuous narrowing of the bandgap in this halide crystal. The hydrogen bonding interactions between inorganic layers and organic amine cations (N-H…Br and O-H…Br hydrogen bonds) efficiently modulate the organic amine cations penetration and the octahedral distortion. Consequently, this phenomenon induces a phase transition and results in red-shifted PL emissions, leading to the near-full-spectrum emission. This work opens a possibility for achieving wide PL emissions with coverage across the visible light spectrum by employing high pressure in single halide perovskites.

[Mechanism of Modified Huoluo Xiaoling Pills against colorectal cancer based on network pharmacology, molecular docking, and experimental validation].

This study aims to predict the possible targets and related signaling pathways of Modified Huoluo Xiaoling Pills against colorectal cancer(CRC) by both network pharmacology and molecular docking and verify the mechanism of action by experiments. TCMSP was used to obtain the active ingredients and targets of Modified Huoluo Xiaoling Pills, and GeneCards, DrugBank, OMIM, and TTD were employed to acquire CRC-related targets. Cytoscape software was utilized to construct the drug-active ingredient-target network, and the STRING database was applied to establish the protein-protein interaction(PPI) network. DAVID platform was adopted to investigate the targets in terms of GO function and KEGG pathway enrichment analysis. Molecular docking was performed in AutoDock Vina. HCT 116 cells were intervened by different concentrations of Modified Huoluo Xiaoling Pills-containing serum, and CCK-8 was used to detect the proliferation inhibition of HCT 116 cells in each group. Transwell was employed to show the invasive abi-lity of HCT 116 cells, and Western blot was taken to reveal the expression levels of ß-catenin, cyclinD1, c-Myc, as well as epithelial-mesenchymal transition(EMT) marker proteins E-cadherin, N-cadherin, vimentin, MMP2, MMP7, MMP9, and TWIST in HCT 116 cells. The network pharmacological analysis yielded 242 active ingredients of Modified Huoluo Xiaoling Pills, 1 844 CRC targets, and 127 overlapping targets of CRC and Modified Huoluo Xiaoling Pills, and the signaling pathways related to CRC involved PI3K-Akt, TNF, HIF-1, IL-17, Wnt, etc. Molecular docking showed that the key active ingredients had a stable binding conformation with the core proteins. CCK-8 indicated that Modified Huoluo Xiaoling Pills significantly inhibited the proliferation of HCT 116 cells. Transwell assay showed that with increasing concentration of Modified Huoluo Xiaoling Pills containing serum, the invasive ability of HCT 116 cells was more obviously inhibited. The expression of ß-catenin, cyclinD1, c-Myc, N-cadherin, vimentin, MMP2, MMP7, MMP9, and TWIST proteins were suppressed, and the expression of E-cadherin was improved by the intervention of drug-containing serum. Thus, it can be seen that Modified Huoluo Xiaoling Pills restrains the proliferation, invasion, and metastasis of CRC cells through multiple components, multiple targets, and multiple pathways, and the mechanism of action may be related to the inhibition of the activation of the Wnt/ß-catenin signaling pathway, thereby affecting the occurrence of EMT.

Humoral and cellular immune responses following Omicron BA.2.2 breakthrough infection and Omicron BA.5 reinfection.

The emergence of novel Omicron subvariants has raised concerns regarding the efficacy of immunity induced by prior Omicron subvariants breakthrough infection (BTI) or reinfection against current circulating Omicron subvariants. Here, we prospectively investigated the durability of antibody and T cell responses in individuals post Omicron BA.2.2 BTI, with or without subsequent Omicron BA.5 reinfection. Our findings reveal that the emerging Omicron subvariants, including CH.1.1, XBB, and JN.1, exhibit extensive immune evasion induced by previous infections. Notably, the level of IgG and neutralizing antibodies were found to correlate with subsequent Omicron BA.5 reinfection. Fortunately, T cell responses recognizing both Omicron BA.2 and CH.1.1 peptides were observed. Furthermore, Omicron BA.5 reinfection may alleviate immune imprinting induced by WT-vaccination, bolster virus-specific ICS+ T cell responses, and promote the phenotypic differentiation of virus-specific memory CD8+ T cells. Antigen-updated or T cell-conserved vaccines are needed to control the transmission of diverse emerging SARS-CoV-2 variants.

Role of gut/liver metabolites and gut microbiota in liver fibrosis caused by cholestasis.

AIM OF THE STUDY: Cholestasis induces severe liver injury and subsequent liver fibrosis. However, a comprehensive understanding of the relationships between liver fibrosis and cholestasis-induced changes in metabolites in the gut and fibrotic liver tissue and in the gut microbiota is insufficient. METHODS: Common bile duct ligation (BDL) was employed to establish a cholestatic liver fibrosis model in mice for 26 days. Fibrotic liver tissue and the gut contents were collected. Untargeted metabolomics was conducted for the determination of metabolites in the gut contents and liver tissues. Metagenomics was adopted to explore the gut microbiota. RESULTS: The metabolites in the gut contents and liver tissues between normal and cholestatic liver fibrosis mice were highly distinct. Beta-alanine metabolism and glutathione metabolism were downregulated in the gut of the BDL group. Galactose metabolism, biosynthesis of unsaturated fatty acids, and ABC transporters were upregulated in the gut and downregulated in the liver of the BDL group. Arginine biosynthesis, taurine and hypotaurine metabolism, arginine and proline metabolism, and primary bile acid biosynthesis were downregulated in the gut and upregulated in the liver of the BDL group. Metagenomic analysis revealed that the alpha diversity of the microbiota in the BDL group decreased. The altered structure of the gut microbiota in the BDL group led to the hypofunction of important metabolic pathways (such as folate biosynthesis, histidine metabolism, thiamine metabolism, biotin metabolism, and phenylalanine, tyrosine and tryptophan biosynthesis) and enzymes (such as NADH, DNA helicase, and DNA-directed DNA polymerase). Correlation analyses indicated that certain gut microbes were associated with gut and liver metabolites. CONCLUSIONS: Untargeted metabolomics and metagenomics provided comprehensive information on gut and liver metabolism and gut microbiota in mice with cholestatic liver fibrosis. Therefore, significantly altered bacteria and metabolites may help provide some targets against cholestatic liver fibrosis in the future.

Influence of tumor thrombus morphology on the surgical complexity in renal cell carcinoma with inferior vena cava tumor thrombus: a single-center, large-sample study from China.

BACKGROUND: The morphology of tumor thrombus varies from person to person and it may affect surgical methods and tumor prognosis. However, studies on the morphology of tumor thrombus are limited. The purpose of our study was to evaluate the impact of tumor thrombus morphology on surgical complexity. METHODS: We retrospectively reviewed the clinical data of 229 patients with renal cell carcinoma combined with inferior vena cava (IVC) tumor thrombus who underwent surgical treatment at Peking University Third Hospital between January 2014 and December 2021. The patients were divided into floating morphology (107 patients) and filled morphology (122 patients) tumor thrombi groups. Chi-square and Mann-Whitney U tests were used for categorical and continuous variables, respectively. Postoperative complications were evaluated using the Clavien-Dindo surgical complication classification method. RESULTS: Patients with filled morphology tumor thrombus required more surgical techniques than those with floating morphology tumor thrombus, which was reflected in more open surgeries (P < 0.001), more IVC interruptions (P <0.001), lesser use of the delayed occlusion of the proximal inferior vena cava (DOPI) technique (P < 0.001), and a greater need for cut-off of the short hepatic vein (P < 0.001) and liver dissociation (P = 0.001). Filled morphology significantly increased the difficulty of surgery in patients with renal cell carcinoma with tumor thrombus, reflected in longer operation time (P < 0.001), more surgical blood loss (P <0.001), more intra-operative blood transfusion (P < 0.001), and longer postoperative hospital stay (P < 0.001). Filled morphology tumor thrombus also led to more postoperative complications (53% vs. 20%; P < 0.001). CONCLUSION: Compared with floating morphology thrombus, filled morphology thrombus significantly increased the difficulty of surgery in patients with renal cell carcinoma with IVC tumor thrombus.

Herpotrichone A Exerts Neuroprotective Effects by Relieving Ferroptosis.

Inhibition of oxidative stress and ferroptosis is currently considered to be a promising therapeutic approach for neurodegenerative diseases. Herpotrichones, a class of compounds derived from insect symbionts, have shown potential for neuroprotective activity with low toxicity. However, the specific mechanisms through which herpotrichones exert their neuroprotective effects remain to be fully elucidated. In this study, the natural [4 + 2] adducts herpotrichone A (He-A) and its new analogues were isolated from the isopod-associated fungus Herpotrichia sp. SF09 and exhibited significantly protective effects in H2O2-, 6-OHDA-, and RSL3-stimulated PC12 cells and LPS-stimulated BV-2 cells. Moreover, He-A was able to relieve ferroptotic cell death in RSL3-stimulated PC12 cells and 6-OHDA-induced zebrafish larvae. Interestingly, He-A can activate antioxidant elements and modulate the SLC7A11 pathway without capturing oxidic free radical and chelating iron. These findings highlight He-A as a novel hit that protects against ferroptosis-like neuronal damage in the treatment of neurodegenerative diseases.

Melatonin-Induced Chromium Tolerance Requires Hydrogen Sulfide Signaling in Maize.

Both melatonin and hydrogen sulfide (H2S) mitigate chromium (Cr) toxicity in plants, but the specific interaction between melatonin and H2S in Cr detoxification remains unclear. In this study, the interaction between melatonin and H2S in Cr detoxification was elucidated by measuring cell wall polysaccharide metabolism and antioxidant enzyme activity in maize. The findings revealed that exposure to Cr stress (100 µM K2Cr2O7) resulted in the upregulation of L-/D-cysteine desulfhydrase (LCD/DCD) gene expression, leading to a 77.8% and 27.3% increase in endogenous H2S levels in maize leaves and roots, respectively. Similarly, the endogenous melatonin system is activated in response to Cr stress. We found that melatonin had a significant impact on the relative expression of LCD/DCD, leading to a 103.3% and 116.7% increase in endogenous H2S levels in maize leaves and roots, respectively. In contrast, NaHS had minimal effects on the relative mRNA expression of serotonin-Nacetyltransferase (SNAT) and endogenous melatonin levels. The production of H2S induced by melatonin is accompanied by an increase in Cr tolerance, as evidenced by elevated gene expression, elevated cell wall polysaccharide content, increased pectin methylesterase activity, and improved antioxidant enzyme activity. The scavenging of H2S decreases the melatonin-induced Cr tolerance, while the inhibitor of melatonin synthesis, p-chlorophenylalanine (p-CPA), has minimal impact on H2S-induced Cr tolerance. In conclusion, our findings suggest that H2S serves as a downstream signaling molecule involved in melatonin-induced Cr tolerance in maize.

Clinical efficacy of Gamma Knife® combined with transarterial chemoembolization and immunotherapy in the treatment of primary liver cancer.

BACKGROUND: This study was designed to investigate the clinical efficacy and safety of Gamma Knife® combined with transarterial chemoembolization (TACE) and immunotherapy in the treatment of primary liver cancer. AIM: To investigate the clinical efficacy and safety of Gamma Knife® combined with TACE and immune-targeted therapy in the treatment of primary liver cancer. METHODS: Clinical data from 51 patients with primary liver cancer admitted to our hospital between May 2018 and October 2022 were retrospectively collected. All patients underwent Gamma Knife® treatment combined with TACE and immunotherapy. The clinical efficacy, changes in liver function, overall survival (OS), and progression-free survival (PFS) of patients with different treatment responses were evaluated, and adverse reactions were recorded. RESULTS: The last follow-up for this study was conducted on October 31, 2023. Clinical evaluation of the 51 patients with primary liver cancer revealed a partial response (PR) in 27 patients, accounting for 52.94% (27/51); stable disease (SD) in 16 patients, accounting for 31.37% (16/51); and progressive disease (PD) in 8 patients, accounting for 15.69% (8/51). The objective response rate was 52.94%, and the disease control rate was 84.31%. Alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alpha-fetoprotein isoform levels decreased after treatment compared with pretreatment (all P = 0.000). The median OS was 26 months [95% confidence interval (95%CI): 19.946-32.054] in the PR group and 19 months (95%CI: 14.156-23.125) in the SD + PD group, with a statistically significant difference (P = 0.015). The median PFS was 20 months (95%CI: 18.441-34.559) in the PR group and 12 months (95%CI: 8.745-13.425) in the SD + PD group, with a statistically significant difference (P = 0.002). Common adverse reactions during treatment included nausea and vomiting (39.22%), thrombocytopenia (27.45%), and leukopenia (25.49%), with no treatment-related deaths reported. CONCLUSION: Gamma Knife® combined with TACE and immune-targeted therapy is safe and effective in the treatment of primary liver cancer and has a good effect on improving the clinical benefit rate and liver function of patients.

Three new flavonoids from the roots of Sophora tonkinensis.

Three new flavonoids including two isoflavanones sophortones A and B (1 and 2), and one chalcone sophortone C (3) were isolated from the roots of Sophora tonkinensis. Their structures were established by UV, IR, HRESIMS, and NMR data. The absolute configurations of 1 and 2 were determined by electronic circular dichroism (ECD) calculations.