- Quantitation of monosaccharide isotopic enrichment in physiologic fluids by electron ionization or negative chemical ionization GC/MS using Di-O-isopropylidene derivatives
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The aldonitrile pentaacetate and other derivatives lack ions in the electron ionization (EI) spectra possessing an intact hexose structure and thus must be analyzed by chemical ionization GC/MS in order to study multiple isotopomers. We report methods for quantitation of hexose di-O-isopropylidene acetate (IPAc) or pentafluorobenzoyl (PFBz) esters. These were prepared in a two-step procedure using inexpensive reagents that do not adversely impact the isotopomer structure of the sugar. The acetate derivative possesses an abundant [M - CH3] ion in the EI spectrum which is suitable for quantitative analysis of isotopomers. The negative chemical ionization (NCI) spectrum of the corresponding pentafluorobenzoyl derivative has a dominant molecular anion. Moreover, the PFBz derivative is about 100-fold more sensitive than the acetate, which offers some advantages for analysis of minor hexoses found in plasma. Isotopic calibration curves of [U-13C]glucose are linear over the 0.1-60% tracer/tracee range tested. The useful range for isotopic tracer studies is 25-2500 pmol for EI analysis of the acetate derivative and 0.1-55 pmol for NCI analysis of PFBz derivative (sample amount injected). For most studies where sample size is not limited, EI-GC/MS analysis of the IPAc derivative is preferred. NCI-GC/MS analysis is reserved when sample size is limiting or when studies involve hexoses other than glucose that are normally present at low concentration.
- Hachey, David L.,Parsons, W. Reed,McKay, Siripoom,Haymond, Morey W.
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- Visible-Light-Induced Pd-Catalyzed Radical Strategy for Constructing C-Vinyl Glycosides
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A novel visible-light-induced palladium-catalyzed Heck reaction for bromine sugars and aryl olefins with high regio- and stereochemistry selectivity for the preparation of C-glycosyl styrene is described. This reaction takes place in one step at room temperature by using a simple and readily available starting material. This protocol can be scaled up to a wide range of glycosyl bromide donors and aryl olefin substrates. Mechanistic studies indicate that a radical addition pathway is involved.
- Li, Ming,Qiu, Yi-Feng,Wang, Cui-Tian,Li, Xue-Song,Wei, Wan-Xu,Wang, Yu-Zhao,Bao, Qiao-Fei,Ding, Ya-Nan,Shi, Wei-Yu,Liang, Yong-Min
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- Chemoselective and Diastereoselective Synthesis of C-Aryl Nucleoside Analogues by Nickel-Catalyzed Cross-Coupling of Furanosyl Acetates with Aryl Iodides
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Canonical nucleosides are vulnerable to enzymatic and chemical degradation, yet their stable mimics—C-aryl nucleosides—have demonstrated potential utility in medicinal chemistry, chemical biology, and synthetic biology, although current synthetic methods remain limited in terms of scope and selectivity. Herein, we report a cross-electrophile coupling to prepare C-aryl nucleoside analogues from readily available furanosyl acetates and aryl iodides. This nickel-catalyzed modular approach is characterized by mild reaction conditions, broad substrate scope, excellent β-selectivity, and high functional-group compatibility. The exclusive chemoselectivity with respect to the aryl iodide enables efficient preparation of a variety of C-aryl halide furanosides suitable for various downstream transformations. The practicality of this transformation is demonstrated through the synthesis of a potent analogue of a naturally occurring NF-κB activator.
- Li, Chao,Li, Luyang,Li, Yuxi,Shao, Feng,Tian, Xiaoying,Wang, Zheng
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supporting information
(2021/11/30)
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- Intramolecular hydrogen abstraction reaction promoted by alkoxy radicals in carbohydrates. Synthesis of chiral 2,7-dioxabicyclo[2.2.1]heptane and 6,8-dioxabicyclo[3.2.1]octane ring systems
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The reaction of specifically protected anhydroalditols with (diacetoxyiodo)benzene or iodosylbenzene and iodine is a mild and selective procedure for the synthesis of chiral 6,8-dioxabicyclo [3.2.1]octane and 2,7-dioxabicyclo[2.2.1]heptane ring systems under neutral conditions. This reaction can be considered to be an intramolecular glycosidation that goes through an intramolecular hydrogen abstraction promoted by an alkoxy radical followed by oxidation of the transient C-radical intermediate to an oxycarbenium ion. This methodology is useful not only for the preparation of chiral synthons but also for the selective oxidation of specific carbons of the carbohydrate skeleton, constituting a good procedure for the synthesis of protected uloses.
- Francisco, Cosme G.,Herrera, Antonio J.,Suarez, Ernesto
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p. 7439 - 7445
(2007/10/03)
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- A convenient preparation of 5-benzyl ethers of D-gluco- and D-manno-furanose derivatives
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Keywords: Glucofuranose; Mannofuranose; Selective benzylation; Two-phase benzylation
- Stepowska, Halszka,Zamojski, Aleksander
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p. 133 - 138
(2007/10/02)
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- SYNTHESES OF 1-O-ACYLALDOSE DERIVATIVES via THE CORRESPONDING O-GLYCOSYLPSEUDOUREAS
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A series of 1-O-acylaldose derivatives was prepared in good yield throught the reaction of 1,3-dialkyl-O-glycosylpseudoureas with carboxylic acids.
- Tsutsumi, Hideo,Ishido, Yoshiharu
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