Results 41 to 50 of about 15,429 (247)

Unveiling the Origin of the Selectivity and the Molecular Mechanism in the [3+2] Cycloaddition Reaction of N-aryl-C-carbamoylnitrone with N-arylitaconimide

Organics, 2022
The [3+2] cycloaddition reaction of N-aryl-C-carbamoylnitrone (nitrone 1) with N-arylitaconimide (ethylene 2) was computationally studied using the B3LYP/6-31G(d) level of theory. An analysis of the different energetic profiles and the transition states’
Abdelmalek Khorief Nacereddine, Fouad Chafaa   +1 more
doaj   +1 more source

Atroposelective Access to π‐Conjugated 1,2‐Azaborepines Enabled by Palladium‐Catalyzed Cyclization of N‐Heterobiaryls with Alkynylboronates

Advanced Science, EarlyView.
We report a palladium‐catalyzed atroposelective cyclization of N‐heterobiaryl triflates with alkynyl boronates to access seven‐membered 1,2‐BN‐bridged biaryls with high yields and excellent enantioselectivity via a cascade DyKAT, cis‐carbopalladation, and 1,2‐migration, which expands the toolbox for axially chiral π‐conjugated boron compounds and opens
Fengya He, Zhen Wang, Haoyu Guo, Shuguang Chen, Xu Zhang, Yongjia Shang, Hui Wang   +6 more
wiley   +1 more source

Chemoenzymatic Synthesis of Heparan Sulfate Oligosaccharides by a Covalent Catch‐and‐Release Approach

Angewandte Chemie, EarlyView.
A glycan having a hydrazide tag enables chemoenzymatic synthesis of HS oligosaccharides. The hydrazide can, under mild acidic conditions, react with an aldehyde‐containing resin to give an immobilized hydrazone that is stable under neutral conditions, allowing washing. The product can be released by transiminolysis using aqueous hydroxylamine to give a
Francesco Palmieri, Chin Huang, Digantkumar Chapla, Kelley W. Moremen, Geert‐Jan Boons   +4 more
wiley   +2 more sources

Ligand-controlled regiodivergent arylation of aryl(alkyl)alkynes and asymmetric synthesis of axially chiral 9-alkylidene-9,10-dihydroanthracenes

Nature Communications
Transition metal-catalyzed addition of organometallics to aryl(alkyl)alkynes has been well known to proceed with the regioselectivity in forming a carbon–carbon bond at the alkyl-substituted carbon (β-addition).
Chao Sun, Ting Qi, Faiz-Ur Rahman, Tamio Hayashi, Jialin Ming   +4 more
doaj   +1 more source

Semi-rational engineering of an α-L-fucosidase for regioselective synthesis of fucosyl-N-acetylglucosamine disaccharides

Food Chemistry: Molecular Sciences
α-L-Fucosidases are attractive biocatalysts for the production of bioactive fucosylated oligosaccharides, however, poor regioselectivity and activity for transglycosylation have significantly limited their applications.
Peng Liu, Xiaodi Chen, Xueting Cao, Yuying Wang, Yafei Gao, Li Xu, Xukai Jiang, Min Xiao   +7 more
doaj   +1 more source

Heterogeneous Catalysts in Pictet-Spengler-Type Reactions

Journal of Chemistry, 2013
Several solid catalysts were evaluated as an alternative for 1,2,3,4-tetrahydroisoquinoline synthesis by means of the Pictet-Spengler reaction. The reaction catalysed by a mixed oxide (Mg and Al) led to the best yield and good regioselectivity; using an ...
Rodolfo Quevedo, Camilo Perdomo, Sonia Moreno   +2 more
doaj   +1 more source

A Simple and Easily Implemented Method for the Regioselective Introduction of Deuterium into Azolo[1,5-a]pyrimidines Molecules

Molecules, 2023
A method for the technically easy-to-implement synthesis of deuterium-labeled pyrazolo[1,5-a]pyrimidines and 1,2,4-triazolo[1,5-a]pyrimidines have been developed. The regioselectivity of such transformations has been shown.
Gevorg G. Danagulyan, Henrik A. Panosyan, Vache K. Gharibyan, Ani H. Hasratyan   +3 more
doaj   +1 more source

Tandem Duplication‐Driven Neofunctionalization of UDP‐Glycosyltransferases Shapes the Diversification of Triterpenoid Saponins in the Cucurbitaceae

Advanced Science, EarlyView.
We present a chromosome‐level genome assembly of Siraitia grosvenorii and, through comparative genomics, uncover a conserved UGT73 tandem array driving triterpenoid saponin diversification in Cucurbitaceae. Crystalized SgUGT73AM30 further reveals the regioselectivity mechanism underlying its catalytic activity.
Guangyi Wang, Mengmeng Li, Xuehui Dai, Yanchen Zhang, Yuhan Wu, Zhaotao Yan, Chenfei Tian, Hongkai Fan, Haili Liu, Xiaowei Zhang, Yiming Yang, Jiayu Lu, Yuwei Sun, Yong Wang   +13 more
wiley   +1 more source

Exclusive Hydroformylation of Terminal Olefins: A Phosphorus‐Free Ruthenium System for the Selective Functionalization of Complex Mixtures

Angewandte Chemie, EarlyView.
Development of a phosphorus‐free Ru/DBU catalyst enabling highly chemo‐ and regioselective hydroformylation of terminal olefins, sparing internal double bonds. Optimization of reaction parameters, ligand effects, and substrate scope including industrial feedstocks was realized.
Mohamed Niyaz Vellala Syed Ali, Ida Ziccarelli, Dilver Peña Fuentes, Christoph Kubis, Robert Franke, Ralf Jackstell, Matthias Beller   +6 more
wiley   +2 more sources

Tailoring Regioselectivity‐Controlled UDP‐Glycosyltransferase for Bidirectional Glycosylation of Tyrosol via Free Energy‐Driven Pocket Reshaping and Tunnel Engineering

Advanced Science
UDP‐glycosyltransferases (UGTs) are pivotal biocatalysts for synthesizing pharmaceutically valuable active components; however, their application is frequently constrained by poor regioselectivity and suboptimal catalytic efficiency.
Ziyu Zhang, Jingyi Chen, Zuozhi Liang, Wenming Shao, Zhen Gao, Bin Wu, Bingfang He, Gerhard Schenk   +7 more
doaj   +1 more source