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This work implements a catalytic SN2 glycosylation by employing an amide-functionalized 1-naphthoate platform as a latent glycosyl leaving group. Upon gold-catalyzed activation, the amide group enables the SN2 process by directing the attack of the glycosyl acceptor via H-bonding interaction, which results in stereoinversion at the anomeric center. Unique in this approach is that the amide group also enables a novel safeguarding mechanism by trapping oxocarbenium intermediates and, hence, minimizing stereorandom SN1 processes. The strategy is applicable to the synthesis of a broad range of glycosides with high to excellent levels of stereoinversion from anomerically pure/enriched glycosyl donors. These reactions are generally high-yielding, and their applications in the synthesis of challenging 1,2-cis-linkage-rich oligosaccharides are demonstrated.

An oxidative strategy is reported to access α-oxo BMIDA gold carbenes directly from BMIDA-terminated alkynes. Besides offering expedient access to seldom studied boryl metal carbenes, these BMIDA gold carbene species undergo facile insertions into methyl, methylene, methine, and benzylic C-H bonds in the absence of the Thorpe-Ingold effect. They also undergo efficient OH insertion, cyclopropanation, and F-C alkylations. This chemistry provides rapid access to structurally diverse α-BMIDA ketones, which are scarcely documented. In combination with DFT studies, the role of BMIDA is established to be an electron-donating group that attenuates the high electrophilicity of the gold carbene center.

Gold allenylidene species have been seldom exploited as reactive intermediates in synthetically versatile catalytic reactions. By employing alkynylbenziodoxoles as the substrates and bifunctional WangPhos as the metal ligand, this work demonstrated ready catalytic access to these intermediates of general substitution patterns and their electrophilic reactivities at the γ‐carbon center with a diverse range of nucleophiles. The reaction is driven by the reductive decomposition of the benziodoxole moiety and achieves the replacement of a propargylic proton with an N/O/C‐based nucleophile, hence realizing reactivity umpolung. Corroborated by Density Functional Theory (DFT) calculations, the reaction mechanism involves a mild propargylic deprotonation. In contrast to prior works employing a tertiary amine functionality, a weakly BrØnsted‐basic amide group in WangPhos is surprisingly effective in deprotonation at the propargylic position under a gold‐ligand cooperation regime. [ABSTRACT FROM AUTHOR]

In order to understand the active mesoscale processes in the Kuroshio extension (KE) region, and reveal the three-dimensional structure of mesoscale eddies in this region, as well as the contributions of mesoscale eddies to water mass redistribution and ocean-atmosphere interactions, based on shipboard observations and satellite remote sensing data, this study investigates the three-dimensional structural characteristics of a typical eddy dipole composed of cyclonic eddy (CE) and an anticyclonic eddy (AE) distributed on the north and south sides of the KE axis, respectively, during June-July 2022. Results show that the CE has a southward cross-frontal motion dominated by shear forcing, while the AE remains relatively stable. The "cold tongue" structure of the CE gradually diminishes due to sea surface warming and heat diffusion from the KE axis, with the AE exhibiting a "reverse eddy sea surface temperature anomaly" structure due to the entrainment of cold water carried by the CE. The vertical multi-cores of internal temperature and salinity anomalies in the eddy dipole are related to the vertical redistribution of water masses with different characteristics. The AE's internal flow field is strongly baroclinic, with around 50% of it having a Richardson number less than the critical value of 0.25, indicating a tendency for turbulent mixing. The upper layer of the CE is barotropic, hindering substantial diapycnal mixing. This study helps to enhance understanding of the eddy dipole characteristics and internal structure of eddies in the KE region, providing information for further research on eddy dynamics. [ABSTRACT FROM AUTHOR]

A series of ruthenium bis(σ‐B−H) borate complexes 1–4 have been prepared by a salt‐elimination protocol using lithium monoaryl trihydroborates Li[ArBH3] (R=Ph, 3,5‐(CF3)2C6H3, o‐tol or Mes) and the corresponding metal halide Cp*Ru(PCy3)Cl. All of these bis(σ‐B−H) borate complexes are stable at room temperature and isolated in good yields (70–92 %). Additionally, treatment of 4 with the hydride abstracting agent B(C6F5)3 generated rare cationic bis(σ‐B−H) borane complex 5. Crystallographic characterization data are provided for 3 and 5. All these new complexes were fully characterized by multinuclear NMR spectroscopy and elemental analysis. [ABSTRACT FROM AUTHOR]

The transition rules of cellular automata (CA) werestrengthened by incorporating annual growth rate (AGR) to reflect spatially heterogeneous neighbourhoods. We conducted hotspot (AGRHST) and gradient (AGRGDT) analysis of AGR to generate two spatial heterogeneity layers, then constructed three CA models: AGR-CA, AGRHST-CA and AGRGDT-CA. The modeling results showed that AGR-CA performed best in overall accuracy, AGRGDT-CA was superior to other models in terms of landscape pattern, and AGRHST-CA produced unrealistically smooth boundaries. The simulation accuracy of these models exceeds 89%, indicating that logistic regression-based simulation methods can be substantially improved by strengthening the neighbourhood effects. [ABSTRACT FROM AUTHOR]

We found that significant errors occurred when diurnal data instead of diurnal–nocturnal data were used to calculate the daily sea-air CO2 flux (F). As the errors were mainly associated with the partial pressure of CO2 in seawater (pCO2w) and the sea surface temperature (SST) in the control experiment, pCO2w and SST equations were established, which are called the nocturnal effect of the CO2 flux. The root-mean-square error between the real daily CO2 flux (Freal) and the daily CO2 flux corrected for the nocturnal effect (Fcom) was 11.93 mmol m−2 d−1, which was significantly lower than that between the Freal value and the diurnal CO2 flux (Fday) (46.32 mmol m−2 d−1). Thus, the errors associated with using diurnal data to calculate the CO2 flux can be reduced by accounting for the nocturnal effect. The mean global daily CO2 flux estimated based on the nocturnal effect and the sub-regional pCO2w algorithm (cor_Fcom) was −6.86 mol m−2 y−1 (September 2020–August 2021), which was smaller by 0.75 mol m−2 y−1 than that based solely on the sub-regional pCO2w algorithm (day_Fcom). That is, compared with day_Fcom, the global cor_Fcom value overestimated the CO2 sink of the global ocean by 10.89%. [ABSTRACT FROM AUTHOR]

Dynamic urban growth is affected by various driving factors which are important for building cellular automata (CA) models. Two categories of urban‐growth drivers (i.e., proximity and accessibility) have not been well differentiated in simulating urban patterns. We built two CA models (Pro‐CAPSO and Acc‐CAPSO) using particle swarm optimization (PSO) incorporating the proximity and accessibility drivers and applied these models to simulate urban growth at Zhuji in China. The results show that although both models accurately reproduced urban growth from 2005 to 2015, differences in the allocation of urban cells are apparent. The proximity‐based model yielded a slightly better figure of merit (FOM) of 19.3% during calibration (2005–2010) as compared to the accessibility‐based model with FOM of 17.5%. An opposite trend (FOM 17.5% vs. 18.3%) was found for subsequent validation (2010–2015). The simulations by the Acc‐CAPSO model are closer to the real urban patterns as measured by landscape metrics. The results indicate that accessibility is a relatively robust driver in predicting long‐term future urban growth. For specific regions, urban future scenarios produced by the two models show opposing patterns; in the same areas, when Pro‐CAPSO predicted more new urban cells, Acc‐CAPSO predicted fewer, and vice versa. Our methods are useful for modelers in selecting appropriate factors between proximity and accessibility and arrange the combination to represent human disturbance when simulating urban growth. [ABSTRACT FROM AUTHOR]