- Excited-State Palladium-Catalyzed 1,2-Spin-Center Shift Enables Selective C-2 Reduction, Deuteration, and Iodination of Carbohydrates
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Excited-state catalysis, a process that involves one or more excited catalytic species, has emerged as a powerful tool in organic synthesis because it allows access to the excited-state reaction landscape for the discovery of novel chemical reactivity. Herein, we report the first excited-state palladium-catalyzed 1,2-spin-center shift reaction that enables site-selective functionalization of carbohydrates. The strategy features mild reaction conditions with high levels of regio- and stereoselectivity that tolerate a wide range of functional groups and complex molecular architectures. Mechanistic studies suggest a radical mechanism involving the formation of hybrid palladium species that undergoes a 1,2-spin-center shift followed by the reduction, deuteration, and iodination to afford functionalized 2-deoxy sugars. The new reactivity will provide a general approach for the rapid generation of natural and unnatural carbohydrates.
- Zhao, Gaoyuan,Yao, Wang,Mauro, Jaclyn N.,Ngai, Ming-Yu
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supporting information
p. 1728 - 1734
(2021/02/06)
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- Process for synthesizing card Geleg only (by machine translation)
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The invention discloses a process for synthesizing card Geleg only, in order to 2?Methyl benzoic acid as starting material, use of improvised catalyst, reaction to produce the iodine iodate a in the middle, or in 2?Methyl benzoic acid as starting material, the metal reagent and under the action of catalyst, by adding liquid bromine, synthetic intermediates b; optionally intermediate one or intermediate two acylation reaction with thionyl chloride, to Friedel-crafts reaction produce intermediate three; in order to ALPHA?D?Glucose as raw material, with the reaction protection of all hydroxyl after pivalyl chloride, and then with zinc bromide, trimethyl silane reaction produce intermediate four; three intermediate the intermediate body, connecting delivery into intermediate five; finally under acidic conditions to remove the acyl special fifth heavenly stem, produce the target compound. card Geleg only of the present invention new process for the synthesis of high yield, mild condition, safety and reliability, is suitable for industrial production, raw material is cheap and easy to obtain, it is beneficial to control the production cost. (by machine translation)
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- METHOD FOR PRODUCING a-HALO-TETRAACYL-GLUCOSE
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There is provided an efficient and excellent preparation method of an α-halo-tetraacyl-glucose which is suitable for industrial preparation, which comprises reacting D-glucose or lower alkyl D-glucoside with a reactive derivative of a carboxylic acid and a metal halide to prepare the α-halo-tetraacyl-glucose represented by the formula (III): wherein R represents an optionally substituted lower alkyl group or an optionally substituted aryl group, and X represents a halogen atom, in one step, and the resulting α-halo-tetraacyl-glucose (III) can be converted into a compound of the formula (I) or a salt thereof by subjecting to a conventional method.
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- PROCESS FOR THE PREPARATION OF COMPOUNDS USEFUL AS INHIBITORS OF SGLT2
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The present invention is directed to a novel process for the preparation of compounds of formula (I) and pharmaceutically acceptable salts and solvates thereof; comprising: reacting a compound of formula (V) wherein LG1 is a leaving group, with a mixture of a zinc salt and an organo-lithium reagent; in a first hydrocarbon solvent; at a temperature in the range of from about -78°C to about room temperature; to yield a mixture of the corresponding compound of formula (VI), wherein M1 is lithium, and the zinc salt; admixing to the mixture of the compound of formula (VI) and the zinc salt, a first ether solvent; to yield the corresponding compound of formula (VII), wherein M2 is a reactive zinc species.
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- PROCESS FOR THE PREPARATION OF COMPOUNDS USEFUL AS INHIBITORS OF SGLT2
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The present invention is directed to a novel process for the preparation of compounds having inhibitory activity against sodium-dependent glucose transporter (SGLT) being present in the intestine or kidney.
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- A properly protected sphingosine acceptor for helferich glycosylation
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The synthesis and some examples of glycosylations of a properly protected sphingosine is presented. This compound is suitable for the preparation of glycosphingolipids. It has been used for the synthesis of -mannosylceramide and sulfatide exploiting the anchimeric assistance to address the stereochemistry of the glycosidic bond.
- Michieletti, Mario,Sillani, Laura,Panza, Luigi
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body text
p. 2609 - 2612
(2010/02/28)
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- High-Yield Syntheses of Tetra-O-benzyl-α-D-glucopyranosyl bromide and Tetra-O-pivaloyl-α-D-glucopyranosyl bromide and their Advantage in the Koenigs-Knorr Reaction
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Several improved approaches for the preparation of tetra-O-benzyl-α- D-glucopyranosyl bromide and tetra-O-pivaloyl-α-D-glucopyranosyl bromide are discussed. The importance of these compounds, which are useful glycosyl donors, was demonstrated by successful preparation of cholesteryl glucopyranosides in an almost neutral medium without the formation of orthoesters. In addition, accurate 1H and 13C NMR resonance assignments of the synthesized cholesteryl glycosides were performed by 2D NMR spectroscopy. Springer-Verlag 2006.
- Presser, Armin,Kunert, Olaf,Poetschger, Irmgard
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p. 365 - 374
(2007/10/03)
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- Synthesis of rhododendrin and epi-rhododendrin,
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The first synthesis of rhododendrin 1 and epi-rhododendrin 2 was achieved by starting from ethyl (S)-3-hydroxybutanoate 4, p-bromoanisole and D-glucose.Rhododendrin 1 is known as the hepatoprotective constituent of Taxus baccata L. Keywords: betuligenol / betuloside / epi-rhododendrin / rhododendrin / rhododendrol
- Mori, Kenji,Qian, Zhao-Hui
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p. 382 - 387
(2007/10/02)
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- Glycoside Synthesis Using 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyranosyl Bromide
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In the presence of silver salts the glycosylation of benzyl alcohol and of cholesterol is achieved in high yields by use of 2,3,4,6-tetra-O-pivaloyl-α-D-glucopyranosyl bromide (2).The formation of orthoesters, which often complicates the Koenigs-Knorr reaction using 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (5), is largely suppressed using 2.The preferential formation of the glycoside from the intermediate ion A is a result of the steric influence of the tert-butyl substituent which hinders nucleophilic attack at the acyloxonium carbon atom and steers the reaction in the desired direction.
- Kunz, Horst,Harreus, Albrecht
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