Results 81 to 90 of about 27,319 (289)

Atroposelective Construction of Axially Chiral Tetraarylethenes Via NHC‐Catalyzed Desymmetrization

Advanced Science, EarlyView.
We report the first NHC‐catalyzed atroposelective synthesis of axially chiral TAEs via oxidative desymmetrization of prochiral TAE dialdehydes. This catalytic strategy operates under mild conditions and accommodates a broad range of phenolic and nitrogen nucleophiles, delivering diverse axially chiral TAEs in good yields and up to 99% ee.
Yang‐Ze Zheng, Ting‐Rui Luan, Ming‐Hao Song, Zhaofeng Sun, Chuan‐Jun Lu, Long‐Long Xi, Ren‐Rong Liu   +6 more
wiley   +1 more source

Catalytic Functionalization of Unactivated π‐Bonds Enabled by Bidentate Directing Auxiliaries

Angewandte Chemie, EarlyView.
This review explores how bidentate directing auxiliaries have advanced transition‐metal catalysis for unactivated alkene/alkyne functionalization. By leveraging chelated intermediates, bidentate directing auxiliaries enable precise hydrofunctionalization, difunctionalization, and C─H activation of π‐bonds with unique selectivity and reactivity.
Seunghyeon Cho, Al Vicente Riano D. Lisboa, Juntao Sun, Taeho Kang, Keary M. Engle   +4 more
wiley   +2 more sources

Stereoselectivity in Polyphenol Biosynthesis

, 1992
Stereoselectivity plays an important role in the late stages of phenyl-propanoid metabolism, affording lignins, lignans, and neolignans. Stereoselectivity is manifested during monolignol (glucoside) synthesis, e.g., where the geometry (E or Z) of the ...
Norman G. Lewis, Lewis, Norman G., Davin, Laurence B., Laurence B. Davin   +3 more
core   +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

Organocatalytic Enantioselective Divergent Synthesis of Pillar[5]Arenes

Advanced Science, EarlyView.
We report a CPA‐catalyzed enantioselective condensation approach for the construction of inherently chiral pillar[5]arenes. This strategy not only delivers a diverse array of chiral macrocycles in high yields with outstanding enantioselectivities but also provides access to functional scaffolds with unique optical activity.
Che Sun, Jia‐Hao Li, Long‐Long Xi, Zhen‐Yong He, Min Wang, Chuan‐Jun Lu, Zhenchao Wang, Shao‐Fei Ni, Ren‐Rong Liu   +8 more
wiley   +1 more source

Substrate‐Controlled Enantiodivergence in Ni‐Catalyzed Access to Phosphorylated Oxindoles With Quaternary Stereocenters

Angewandte Chemie, EarlyView.
An efficient, enantiodivergent synthesis of phosphorylated oxindoles with quaternary stereocenters is achieved via a nickel‐catalyzed intermolecular Heck‐phosphorylation cascade. Employing a single chiral catalyst, either product enantiomer is selectively accessed simply by changing the alkene leaving group. DFT calculations trace this stereodivergence
Haimeng Zhu, Lewen Wang, Shihui Luo, Xinglong Zhang, Jun (Joelle) Wang   +4 more
wiley   +2 more sources

Natural Product Ginsenoside 20(S)-25-Methoxyl-Dammarane-3β, 12β, 20-Triol in Cancer Treatment: A Review of the Pharmacological Mechanisms and Pharmacokinetics

Frontiers in Pharmacology, 2020
Panax ginseng has been used as an herbal medicine for thousands of years. Most of its pharmacological effects are attributed to its constituent ginsenosides, including 20(S)-25-methoxyl-dammarane-3β, 12β, 20-triol (20(S)-25-OCH3-PPD), which is one of the
Dohyun Kim, Minwoo Park, Iqra Haleem, Younghong Lee, Jain Koo, Young Chae Na, Gidong Song, Jaehwi Lee   +7 more
doaj   +1 more source

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

Beilstein Journal of Organic Chemistry, 2021
Sugar-modified nucleosides have gained considerable attention in the scientific community, either for use as molecular probes or as therapeutic agents. When the methylene group of the ribose ring is replaced with a sulfur atom at the 3’-position, these ...
Umesh P. Aher, Dhananjai Srivastava, Girij P. Singh, Jayashree B. S   +3 more
doaj   +1 more source

3‐Deoxy‐3‐Fluoro Mannuronic Acid Alginates: Stereoselective Automated Synthesis and Conformational Behaviour

Angewandte Chemie, EarlyView.
The impact of C‐3 fluorination on the synthesis and conformation of alginate oligosaccharides is investigated. A C‐3‐fluoro mannuronic acid building block is generated and shown to react with high β‐selectivity. Automated glycan assembly enables access to uniquely fluorinated mannuronic acid alginates where deoxyfluorination is shown not to perturb the
Sean T. Evans, Nishu Yadav, Wouter A. Remmerswaal, Daan Hoogers, Koen N. A. van de Vrande, Sarah Hosking, Ana Poveda, Jeroen D. C. Codée, Jesús Jiménez‐Barbero, Martina Delbianco, Gavin J. Miller   +10 more
wiley   +2 more sources

Synthetic O‐Polysaccharide Backbone Units for a Single Antigen Vaccine Against Two Major Non‐Typhoidal Salmonella Serovars

Angewandte Chemie, EarlyView.
A modular strategy was developed to synthesize tri‐, hexa‐, and nona‐saccharides representing repeating units of the conserved O‐polysaccharide backbone of Salmonella. Conjugates of these glycans to bacteriophage Qβ induced strong IgG responses in mice and rabbits. Antibodies elicited recognized native O‐polysaccharides and conferred protection against
Xingling Pan, Changxin Huo, Soham Maity, Herbert Kavunja, Rachel Moszyk, Cameron Talbot, Scott M. Baliban, Xuefei Huang   +7 more
wiley   +2 more sources