查看更多>>摘要：Compared to electron transporting layer materials,the species and numbers of hole transporting layer(HTL)materials for organic so-lar cells(OSCs)are rare.The development of HTL materials with excellent hole collection ability and non-corrosive nature is a long-standing issue in the field of OSCs.Herein,we designed and synthesized a series of conjugated polyelectrolytes(CPEs)with con-tinuously varied energy levels toward HTL materials for efficient OSCs.Through a"mutual doping"treatment,we obtained a CPE composite PCT-F:POM with a WF of 5.48 eV and a conductivity of 1.56 x 10-3 S/m,meaning that a good hole collection ability can be expected for PCT-F:POM.The OSC modified by PCT-F:POM showed a high PCE of 18.0％,which was superior to the reference device with PEDOT:PSS.Moreover,the PCT-F:POM-based OSC could maintain 91％of the initial PCE value after storage of 20 d,meaning that the long-term stability of OSCs is improved by incorporating the PCT-F:POM HTL.In addition,PCT-F:POM possesses good compatibility with large-area processing technique;i.e.,a PCT-F:POM HTL was processed by the blade-coating method for fabricating 1 cm2 OSC,and a PCE of 15.1％could be achieved.The results suggest the promising perspective of PCT-F:POM in practical applications.
查看更多>>摘要：N,N,N-Trimethyl-D-glucosamine(TMG)-chitotriomycin,a naturally occurring chitin related oligosaccharide,is a specific β-N-acetylhexo-saminidases(HexNAcases)inhibitor for insects and fungi.Although TMG-chitoriomycin holds great promise as a novel class insecticide and fungicide,the limited accessibility of TMG-chitotriomycin prevents its further biological evaluation.We report herein a simple and eco-friendly chemoenzymatic approach for the efficient synthesis of TMG-chitotriomycin and its analogues.In this strategy,the readily available chitosan was enzymatically hydrolyzed and chemically N-acetylated to afford the chitooligosaccharides ranging from disac-charide to hexasaccharide.These chitooligosaccharides were selectively deacetylated by two different chitin deacetylases followed by chemical N-trimethylation to obtain the desired TMG-chitotriomycin and a total of 13 TMG-chitotriomycin analogues in the longest linear sequence of 4 steps in over 12％total yields.
查看更多>>摘要：The activation of inert chemical bonds is an exciting area of research in chemistry because it enables the direct utilization of readily available starting materials and promotes atom-and step-economic synthesis.Undoubtedly,selectively activating and transforming multiple inert chemical bonds is an even more intriguing and demanding task in synthetic chemistry.However,due to its inherent complexity and extreme challenges,this endeavour is rarely accomplished.We report a copper-mediated complete cleavage and se-lective transformation of multiple inert chemical bonds of three easily available feedstocks,i.e.,a sp2C-H bond in indoles,three sp3C—H bonds and one C—N bond in a methyl carbon atom in TMEDA,and the C≡N triple bond in CH3CN.This reaction proceeds via tandem carbon and nitrogen atom transfer,and allows for the direct and efficient cyanation of indoles,presenting a simple and direct alternative for synthesizing 3-cyanoindoles.
查看更多>>摘要：Pd-mediated bioorthogonal cleavage reactions have been extensively utilized in the activation of prodrug molecules,precise regula-tion of protein function,and cellular engineering.However,the availability of cleavable"caging"groups is quite limited,and their ap-plication in nucleic acid modification has seldom been reported.Herein,we introduce a method based on Pd-catalyzed reduction amination of azides as a decaging strategy to activate the activity of biomolecules.We designed modifications on the bioactive sites with azides or their derivatives to mask the related biological function,followed by the release of biological activity through Pd-catalyzed NaBH4 reduction amination reaction.This study has demonstrated that the strategy can effectively be used to activate bioactive molecules such as fluorescent probes,prodrugs,and to regulate the biological function of RNA,including reverse transcrip-tion extension,binding to ligands,and cleavage activity of the CRISPR-Cas system.All results confirm that this strategy provides an ef-ficient and controllable"OFF to ON"biological switch,capable of achieving significant regulatory effects substoichiometrically,and is expected to be extended to other biological applications.
查看更多>>摘要：The strategy of removable glycosylation modification was used to overcome the low-efficiency problem encountered in the chemical synthesis of the mirror-image D-version of the immunoglobulin(Ig)-like domain of tropomyosin receptor kinase A(DIgCTrkA),a protein molecule needed for mirror-image screening of D-peptide ligands targeting this cell membrane receptor.It was found that O-linked-β-N-acetyl-D-glucosamine(O-GIcNAc)modification at DSer312,or DSer320 can significantly improve the efficiency of DIgCTrkA synthesis and folding,while O-GIcNAc modification at DSer330 showed barely any improvement.This study provides a new example demonstrating the power of the removable glycosylation modification strategy in the chemical synthesis and folding of diffi-cult-to-obtain proteins.It also presents evidence that removable glycosylation modification at different sites would significantly affect the efficiency of protein folding promoted by this strategy.
查看更多>>摘要：A novel visible-light-induced radical cascade 6-endo cyclization of dienes(N-(2-vinylphenyl)acryl amides)is developed utilizingα-carbonyl bromides as alkyl reagents.This approach affords an efficient way for synthesizing six-membered benzo-fused lactam de-rivatives with chemo-and regio-selectivity and good functional group tolerance.Primary,secondary,and tertiary bromides are well-compatible with this cascade cyclization reaction.
查看更多>>摘要：A visible light photocatalytic[3+2]cycloaddition of alkynes with readily accessible organic iodides as the C3 synthon is developed herein.By merging halogen atom transfer(XAT)and hydrogen atom transfer(HAT),alkyl/aryl iodides serve as a formal diradical pre-cursor and add across C-C triple bonds to deliver a number of functionalized cyclopentanes in moderate to high yields with exceptional regio-and diastereoselectivity.A reductive radical-polar crossover mechanism,involving the cascade XAT,radical addition,1,5-HAT,polar effect-promoted 5-endo annulation,single electron transfer(SET)reduction,and protonation,may account for this unprece-dented dehalogenative[3+2]cycloaddition.This work not only expands the repertoire of the traditional RATC methodology,but also provides a robust platform for the expedient assembly of cyclopentanes,a valuable structural motif in the realms of medicinal chem-istry and material sciences.
查看更多>>摘要：The implementation of divergent protein engineering on the natural transaminase Vf-ω-TA led to the development of two effective mutants(M2 and M8),enabling the enzymatic synthesis of chiral amine precursors of Rivastigmine and Apremilast,respectively.The evolution of the enzymes was guided by crystal structures and a focused mutagenesis strategy,allowing them to effectively address the challenging ketone substrates with significant steric hindrance.Under the optimized reaction parameters,transamination pro-ceeded smoothly in good conversions and with perfect stereochemical control(＞99％ee).These processes utilize inexpensiveα-methylbenzylamine as an amine donor and avoid the continuous acetone removal and costly LDH/GDH/NADH systems.
查看更多>>摘要：Phthalides serve as core structures pervasive in a wide array of natural products and drug molecules,which display a diverse array of biological activities.We report herein a highly efficient dynamic kinetic resolution of 3-hydroxyphthalides by chiral isothioureas(ITUs)catalyzed asymmetric acylation,facilitating the effective synthesis of a variety of chiral phthalidyl esters with good yields and enanti-oselectivities.Notably,this reaction features mild reaction conditions,expansive substrate scope as well as good functional group compatibility.In addition,the practicality of this method is underscored by the large-scale synthesis,reduced catalyst loading experi-ment and the synthesis of the chiral phthalidyl ester prodrug.
查看更多>>摘要：Catalytic and green strategies for the synthesis of privileged scaffolds are synthetically appealing.We now report a radical-polar crosso-ver(RPC)-enabled three-component cyclization of bromodifluoroalkyls with enaminones and 6-aminouraciles via a visible-light-induced domino cyclization.The reaction exhibited a broad substrate scope(＞40 examples)including complex molecules,which highlighted the utility of this strategy for the construction of a library of bioactive analogs.
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