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The ability to selectively functionalize ubiquitous C-H bonds streamlines the construction of complex molecular architectures from easily available precursors. Here we report enzyme catalysts derived from a cytochrome P450 that use a nitrene transfer mechanism for the enantioselective amination of primary, secondary and tertiary C(sp3)-H bonds. These fully genetically encoded enzymes are produced and function in bacteria, where they can be optimized by directed evolution for a broad spectrum of enantioselective C(sp3)-H amination reactions. These catalysts can aminate a variety of benzylic, allylic and aliphatic C-H bonds in excellent enantioselectivity with access to either antipode of product. Enantioselective amination of primary C(sp3)-H bonds in substrates that bear geminal dimethyl substituents furnished chiral amines that feature a quaternary stereocentre. Moreover, these enzymes enabled the enantioconvergent transformation of racemic substrates that possess a tertiary C(sp3)-H bond to afford products that bear a tetrasubstituted stereocentre, a process that has eluded small-molecule catalysts. Further engineering allowed for the enantioselective construction of methyl-ethyl stereocentres, which is notoriously challenging in asymmetric catalysis.

The development of boron reagents is crucial for synthetic chemistry. Herein, we present a scalable and practical synthesis of diborodichloromethane (DBDCM) through the reaction of trichloromethyllithium with bis(pinacolato)diboron (B2pin2). The resulting DBDCM reagent serves as a basic synthetic unit for the construction of various structurally diverse gem‐diborylalkanes through controllable C−Cl functionalizations. Moreover, we have developed consecutive tetra‐functionalizations of DBDCM for the construction of diverse tertiary and quaternary carbon containing molecules. The use of isotopically enriched 13C‐chloroform and 10B2pin2 enables the synthesis of isotopically enriched 13C‐DBDCM and 10B‐DBDCM reagents, which are beneficial for the convenient synthesis of carbon‐13 and boron‐10 molecules. [ABSTRACT FROM AUTHOR]

Evaluating waterlogging vulnerability and analyzing its characteristics and future trends can provide scientific support for urban disaster prevention and reduction. For this study, taking Fuzhou as an example, an urban waterlogging vulnerability assessment system was constructed from the three dimensions of exposure, sensitivity, and adaptive capacity. The entropy method was used to evaluate urban waterlogging vulnerability in Fuzhou during 2014–2020. The use of CA–Markov to predict waterlogging vulnerability in 2023, 2026, and 2029 in Fuzhou is an important innovation reported in this paper. Study results showed that: (1) Vulnerability to waterlogging in Fuzhou follows a gradually decreasing "center-southeast" distribution pattern, with Level 5 areas mainly located in Cangshan District, Gulou District, and Taijiang District. (2) Changes in waterlogging vulnerability in Fuzhou from 2014 to 2020 can be divided into five change modes, with changing areas, mainly of the late-change type, accounting for 14.13% of the total area. (3) Prediction accuracy verification shows that the CA–Markov model is suitable for predicting waterlogging vulnerability in Fuzhou with high accuracy and a kappa coefficient of 0.9079. (4) From 2020 to 2029, the vulnerability level of the eastern coastal region of Fuzhou is expected to generally increase, and the vulnerability degree will continue to deteriorate. The proportion of Level 5 vulnerable areas will increase by 4.5%, and the growth rate will increase faster and faster with the passage of time. [ABSTRACT FROM AUTHOR]

Carbon-hydrogen (C-H) and carbon-carbon (C-C) bonds are the main constituents of organic matter. Recent advances in C-H functionalization technology have vastly expanded our toolbox for organic synthesis.sup.1. By contrast, C-C activation methods that enable editing of the molecular skeleton remain limited.sup.2-7. Several methods have been proposed for catalytic C-C activation, particularly with ketone substrates, that are typically promoted by using either ring-strain release as a thermodynamic driving force.sup.4,6 or directing groups.sup.5,7 to control the reaction outcome. Although effective, these strategies require substrates that contain highly strained ketones or a preinstalled directing group, or are limited to more specialist substrate classes.sup.5. Here we report a general C-C activation mode driven by aromatization of a pre-aromatic intermediate formed in situ. This reaction is suitable for various ketone substrates, is catalysed by an iridium/phosphine combination and is promoted by a hydrazine reagent and 1,3-dienes. Specifically, the acyl group is removed from the ketone and transformed to a pyrazole, and the resulting alkyl fragment undergoes various transformations. These include the deacetylation of methyl ketones, carbenoid-free formal homologation of aliphatic linear ketones and deconstructive pyrazole synthesis from cyclic ketones. Given that ketones are prevalent in feedstock chemicals, natural products and pharmaceuticals, these transformations could offer strategic bond disconnections in the synthesis of complex bioactive molecules. Aromatization-driven C-C bond activation through iridium/phosphine catalysis enables deacylative transformations in various ketone substrates., Author(s): Yan Xu [sup.1] , Xiaotian Qi [sup.2] , Pengfei Zheng [sup.1] [sup.3] , Carlo C. Berti [sup.1] , Peng Liu [sup.2] , Guangbin Dong [sup.1] Author Affiliations: (1) Department [...]

Green technology adoption is indispensable for sustainable growth. Therefore, this study examines the determinants of green innovation in BRICS countries considering the Triple Bottom Line Theory (social, environmental, and economic). A cross-sectional autoregressive distributed lag (CS-ARDL) model is applied for empirical analysis from 1990 to 2019. The findings show that social, economic, and environmental factors significantly derive green innovation in the long run. However, their marginal contribution is substantially varied. A 1% increase in economic factors increases green innovation by 0.290%, while environmental concerns induce innovation by 0.438% in the long run. In contrast, social factors possess a relatively lower influence on green innovation, with a coefficient magnitude of 0.175%. Lastly, globalization stimulates green innovation by 0.310%. Similar results are observed in the short run; however, the magnitude of variables is significantly lower than long-run. These results are also validated using alternative estimators and recommend TBL factors as core drivers of green innovation in BRICS countries. [ABSTRACT FROM AUTHOR]

This report describes the unprecedented electrooxidation of a solvent (e.g. DMF)‐ligated B2cat2 complex, whereby a solvent‐stabilized boryl radical is formed via quasi‐homolytic cleavage of the B−B bond in a DMF‐ligated B2cat2 radical cation. Cyclic voltammetry and density functional theory provide evidence to support this novel B−B bond activation strategy. Furthermore, a strategy for the electrochemical gem‐diborylation of gem‐bromides via paired electrolysis is developed for the first time, affording a range of versatile gem‐diborylalkanes, which are widely used in synthetic society. Notably, this reaction approach is scalable, transition‐metal‐free, and requires no external activator. [ABSTRACT FROM AUTHOR]