2-Deoxy-β-C-glycosides represent an important class of carbohydrates that are present in many bioactive molecules. However, owing to the lack of substituents at the C2 position, the stereoselective synthesis of 2-deoxy-β-C-glycosides is highly challenging. Herein, we report a ligand-controlled stereoselective C-alkyl glycosylation reaction to access 2-deoxy-β-C-alkyl glycosides from readily available glycals and alkyl halides. This method exhibits broad substrate scope and excellent diastereoselectivity under very mild conditions. In addition, unprecedented stereodivergent synthesis of 2-deoxy-C-ribofuranosides is achieved using different chiral bisoxazoline ligands. Mechanistic studies suggest that hydrometallation of the glycal with the bisoxazoline-ligated Co-H species may be the turnover-limiting and stereodetermining step of this transformation.
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http://dx.doi.org/10.1002/anie.202218544 | DOI Listing |
Nat Commun
October 2024
Leibniz-Institut für Katalyse e.V., 18059, Rostock, Germany.
Four-membered carbocycles are among the most sought-after backbones which are commonly found in biologically active molecules. However, difficulties on their producing are existing due to its highly strained ring system. On the other hand, cyclobutanols can be straightforwardly prepared and can serves as precursors for synthesizing cyclobutane derivatives.
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
A diarylurea-containing phosphine ligand-modulated stereoinvertive -glycosylation with primal furanosyl and pyranosyl -alkynylbenzoate () donors under gold(I) catalysis is disclosed. Both α- and β-configured glycosides could be obtained from the corresponding stereochemically pure β- and α-glycosyl donors with high yields and good to excellent stereoselectivities, respectively. This method accommodates a variety of glycosyl donors and alcoholic acceptors, leading to both 1,2- and 1,2- glycosidic linkages, and has been applied to the convenient preparation of a series of linear arabinan glycans.
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang Province 310030, China.
Owing to substantial advances in the past several decades, transition-metal-catalyzed asymmetric reactions have garnered considerable attention as pivotal methods for constructing chiral molecules from abundant, readily available achiral counterparts. These advances are largely attributed to the development of chiral ligands that control stereochemistry through steric repulsion and other noncovalent interactions between the ligands and functional groups or prochiral centers on the substrates. However, stereocontrol weakens dramatically with increasing distance between the reaction site and the functional group or prochiral center.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2024
Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of Chemistry, Northeast Normal University, Changchun, 130024, China.
We herein describe the first example of ligand-controlled, copper-catalyzed regiodivergent asymmetric difunctionalization of terminal alkynes through a cascade hydroboration and hydroallylation process. The catalytic system, consisting of (R)-DTBM-Segphos and CuBr, could efficiently achieve asymmetric 1,1-difunctionalization of aryl terminal alkynes, while ligand switching to (S,S)-Ph-BPE could result in asymmetric 1,2-difunctionalization exclusively. In addition, alkyl substituted terminal alkynes, especially industrially relevant acetylene and propyne, were also valid feedstocks for asymmetric 1,1-difunctionalization.
View Article and Find Full Text PDFOrg Lett
June 2024
College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China.
A ligand-controlled regiodivergent and stereoselective ring-opening isomerization of vinylcyclopropane was developed with cobalt catalysis. Employing the commercially available Xantphos ligand, the reactions afforded exclusively linear-type 1,3-dienes as the products. Interestingly, when switching the ligand to an amido-diphosphine ligand (PNP), branched-type 1,3-dienes were obtained with high regioselectivity and stereoselectivity.
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