An efficient methodology for the synthesis of α-Kdo glycosidic bonds has been developed with 5,7-O-di-tert-butylsilylene (DTBS) protected Kdo ethyl thioglycosides as glycosyl donors. The approach permits a wide scope of acceptors to be used, thus affording biologically significant Kdo glycosides in good to excellent chemical yields with complete α-selectivity. The synthetic utility of an orthogonally protected Kdo donor has been demonstrated by concise preparation of two α-Kdo-containing oligosaccharides.
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Synthesis of 3- C-Branched Kdo Analogues via Sonogashira Coupling of 3-Iodo Kdo Glycal with Terminal Alkynes.
J Org Chem
June 2018
Shanghai Key Laboratory of New Drug Design, School of Pharmacy , East China University of Science and Technology, 130 Meilong Road , Shanghai 200237 , China.
A highly efficient approach for the synthesis of 3- C-branched mono- and di-3-deoxy-d- manno-oct-2-ulosonic acid (Kdo) enyne analogues is developed for the first time based on Sonogashira coupling of terminal alkynes with 3-iodo Kdo glycal obtained by the NIS/TMSOTf-promoted one-step reaction from peracetylated Kdo ethyl ester. Further transformation of 3- C-branched mono- and di-Kdo enyne analogues by asymmetric hydrogenation and saponification provided 2-deoxy-β-carboxyl Kdo analogues in a stereocontrolled mode.
View Article and Find Full Text PDFStereodirecting Effect of C5-Carboxylate Substituents on the Glycosylation Stereochemistry of 3-Deoxy-d- manno-oct-2-ulosonic Acid (Kdo) Thioglycoside Donors: Stereoselective Synthesis of α- and β-Kdo Glycosides.
J Am Chem Soc
March 2018
Department of Chemistry of Medicinal Natural Products, Sichuan Engineering Laboratory for Plant-Sourced Drug and Research Center for Drug Industrial Technology, West China School of Pharmacy, and State Key Laboratory of Biotherapy , West China Hospital, Sichuan University, Chengdu 610041 , China.
The stereodirecting effect of C5-ester functions on the glycosylation stereoselectivity of 3-deoxy-d- manno-oct-2-ulosonic acid (Kdo) ethyl thioglycoside donors is presented. The coupling of 5- O-arylcarbonyl or acetyl protected Kdo thioglycosides with acceptors proceeds in an α-selective and high-yielding manner, leading to formation of α-linked Kdo glycosides products. On the other hand, the glycosylation stereoselectivity of the 5- O-2-quinolinecarbonyl (Quin) or 4-nitropicoloyl substituted Kdo thioglycoside donors is switchable: (1) The glycosylation of the 5- O-Quin carrying Kdo donors with primary glycosyl acceptors shows complete β-stereoselectivity, furnishing the corresponding β-glycosides in good-to-excellent yield.
View Article and Find Full Text PDFStereoselective Synthesis of α-3-Deoxy-D-manno-oct-2-ulosonic Acid (α-Kdo) Glycosides Using 5,7-O-Di-tert-butylsilylene-Protected Kdo Ethyl Thioglycoside Donors.
Angew Chem Int Ed Engl
September 2015
Department of Chemistry of Medicinal Natural Products, Key Laboratory of Drug Targeting and Drug Delivery Systems of the Ministry of Education, West China School of Pharmacy.
An efficient methodology for the synthesis of α-Kdo glycosidic bonds has been developed with 5,7-O-di-tert-butylsilylene (DTBS) protected Kdo ethyl thioglycosides as glycosyl donors. The approach permits a wide scope of acceptors to be used, thus affording biologically significant Kdo glycosides in good to excellent chemical yields with complete α-selectivity. The synthetic utility of an orthogonally protected Kdo donor has been demonstrated by concise preparation of two α-Kdo-containing oligosaccharides.
View Article and Find Full Text PDFEfficient Large Scale Syntheses of 3-Deoxy-D-manno-2-octulosonic acid (Kdo) and Its Derivatives.
Org Lett
May 2015
School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, Shaanxi 710119, P. R. China.
An efficient method to rapidly synthesize 3-deoxy-D-manno-2-octulosonic acid (Kdo) and its derivatives in large scale has been developed. Starting from D-mannose, the di-O-isopropylidene derivative of Kdo ethyl ester was prepared in three steps on a scale of more than 40 g in one batch in an overall yield of 75-80% without any intermediate purification. Kdo, Kdo glycal, and 2-acetylated Kdo ester were synthesized quickly in high yield from a di-O-isopropylidene derivative of Kdo ethyl ester.
View Article and Find Full Text PDFFormal Synthesis of 3-Deoxy-D-manno-2-Octulosonic Acid (KDO) via a Highly Double-Stereoselective Hetero Diels-Alder Reaction Directed by a (Salen)Co(II) Catalyst and Chiral Diene.
J Org Chem
April 1998
State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai, 200032, China.
This paper presents a formal total synthesis of 3-deoxy-D-manno-2-octulosonic acid (KDO) based on a highly double-stereoselective hetero Diels-Alder reaction between an electron-rich diene and ethyl glyoxylate catalyzed by (Salen)Co(II) complex, a new catalyst for Diels-Alder reactions. A facial specific hydroboration followed by oxidative workup leads to a diol system with the trans-diequatorial arrangement of hydroxyl groups at the C-4 and C-5. Inversion of the configuration of the C-5 hydroxyl group in 12 and then ketal formation afford the desired target diisopropylidene-2-deoxy-KDO methyl ester (18), which can be converted to KDO according to the literature procedure.
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