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Sukhran Y, Alshanski I, Filiba O, Mackintosh MJ, Schapiro I, Hurevich M. Unexpected Nucleophile Masking in Acyl Transfer to Sterically Crowded and Conformationally Restricted Galactosides. J Org Chem 2023. [PMID: 37269328 DOI: 10.1021/acs.joc.3c00878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Design and synthesis of orthogonally protected monosaccharide building blocks are crucial for the preparation of well-defined oligosaccharides in a stereo- and regiocontrolled manner. Selective introduction of protecting groups to partially protected monosaccharides is nontrivial due to the often unpredictable electronic, steric, and conformational effects of the substituents. Abolished reactivity toward a commonly used Lewis base-catalyzed acylation of O-2 was observed in conformationally restricted 4,6-O-benzylidene-3-O-Nap galactoside. Investigation of analogous systems, crystallographic characterization, and quantum chemical calculations highlighted the overlooked conformational and steric considerations, the combination of which produces a unique passivity of the 2-OH nucleophile. Evaluating the role of electrophile counterion and auxiliary base in the acylation of the sterically crowded and conformationally restricted galactoside system revealed an alternative Brønsted base-driven reaction pathway via nucleophilic activation. Insights gained from this model system were utilized to access the target galactoside intermediate within the envisioned synthetic route. The acylation strategy described herein can be implemented in future syntheses of key monomeric building blocks with unique protecting group hierarchies.
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Affiliation(s)
- Yonatan Sukhran
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Israel Alshanski
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Ofer Filiba
- Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Megan J Mackintosh
- Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Mattan Hurevich
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Li X, Wang D, Zhang P, Yu G, Cai C. Recent Advances in the Chemical Synthesis of Marine Acidic Carbohydrates. CURR ORG CHEM 2021. [DOI: 10.2174/1385272824999201230120805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ocean supplies abundant active compounds, including small organic molecules,
proteins, lipids, and carbohydrates, with diverse biological functions. The high-value
transformation of marine carbohydrates primarily refers to their pharmaceutical, food, and
cosmetic applications. However, it is still a big challenge to obtain these marine carbohydrates
in well-defined structures. Synthesis is a powerful approach to access marine oligosaccharides,
polysaccharide derivatives, and glycomimetics. In this review, we focus on the
chemical synthesis of marine acidic carbohydrates with uronic acid building blocks such as
alginate, and glycosaminoglycans. Regioselective sulfation using a chemical approach is also
highlighted in the synthesis of marine oligosaccharides, as well as the multivalent glycodendrimers
and glycopolymers for achieving specific functions. This review summarizes recent
advances in the synthesis of marine acidic carbohydrates, as well as their preliminary structure activity relationship
(SAR) studies, which establishes a foundation for the development of novel marine carbohydrate-based drugs and
functional reagents.
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Affiliation(s)
- Xinru Li
- Key Laboratory of Marine Drugs, Ministry of Education & Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Depeng Wang
- Key Laboratory of Marine Drugs, Ministry of Education & Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Ping Zhang
- Key Laboratory of Marine Drugs, Ministry of Education & Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Guangli Yu
- Key Laboratory of Marine Drugs, Ministry of Education & Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Chao Cai
- Key Laboratory of Marine Drugs, Ministry of Education & Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
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