- Triflic Imide-Catalyzed Glycosylation of Disarmed Glycosyl ortho-Isopropenylphenylacetates and ortho-Isopropenylbenzyl Thioglycosides
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Glycosylation reaction involving the coupling of a glycosyl donor with a glycosyl acceptor is one of the cornerstones of chemical preparation of pure glycans and glycoconjugates of biological relevance. Catalytic glycosylation of glycosyl ester donors and thioglycosides is an attractive but underexplored topic in carbohydrate chemistry. Herein, triflic imide (Tf2NH)-catalyzed glycosylation of various O-, S-, and C-nucleophiles has been achieved using disarmed glycosyl ortho-isopropenylphenylacetates (GIPPAs) and ortho-isopropenylbenzyl thioglycosides as glycosylating agents. The reactions proceed under mild conditions to give the desired glycosides in good-to-excellent yields. Of particular note, the comparable reactivity for the α-isomers and the β-ones of GIPPAs is observed. The mechanistic investigation demonstrates that the isopropenyl group is essential for the reaction and its preferential protonation triggers the reaction. This work provides another member to the arsenals of glycosyl ester and thioglycoside donors suitable for acid-catalyzed glycosylation to create various glycosidic bonds.
- Qiao, Zhi,Wang, Peng,Ni, Jingxuan,Li, Dongwei,Sun, Yao,Li, Tiantian,Li, Ming
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- Enantioselective Copper-Catalyzed Desymmetrization of 1,3-Diketones Involving Borylation of Styrenes
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A copper-catalyzed intramolecular enantioselective and diastereoselective borylative coupling of styrenes and ketones was achieved by merging desymmetrization strategy and olefin difunctionalization. The reaction proceeds through an initial enantioselective borylcupration of styrenes, followed by a highly selective direct addition to 1,3-diketones. The bicyclic scaffolds with three chiral carbon centers, including two tetrasubstituted carbons, were generated in excellent yields, diastereoselectivities, and enantioselectivities. This catalytic tandem reaction has great potential for further synthetic application of the chiral polycyclic compounds, because of the versatility of the functional groups in the products.
- Zheng, Purui,Han, Xiaoyu,Hu, Jiao,Zhao, Xiaoming,Xu, Tao
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supporting information
p. 6040 - 6044
(2019/08/27)
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- Aerobic Photooxidative Synthesis of β-Alkoxy Monohydroperoxides Using an Organo Photoredox Catalyst Controlled by a Base
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Transition-metal-free synthesis of β-alkoxy monohydroperoxides via aerobic photooxidation using an acridinium photocatalyst was developed. This method enables the synthesis of some novel hydroperoxides. The peroxide source is molecular oxygen, which is cost-effective and atomically efficient. Magnesium oxide plays an important role as a base in the catalytic system.
- Asano, Yuya,Nagasawa, Yoshitomo,Yamaguchi, Eiji,Itoh, Akichika
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p. 409 - 412
(2018/02/21)
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- Synthesis of isothiochromenes and 1,3-dihydrobenzo[c]thiophenes by iodine- and hydrobromic acid-mediated cyclizations of o-[(tert-butylsulfanyl)methyl)]styrenes
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Methods for the syntheses of 4-substituted isothiochromenes and 1,1-disubstituted 1,3-dihydrobenzo[c]thiophenes have been developed. Thus, treatment of α-substituted o-[(tert-butylsulfanyl)methyl]styrenes, derived from α-substituted o-bromostyrenes using
- Kobayashi, Kazuhiro,Ueyama, Takuma,Horiuchi, Mai
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p. 2065 - 2079
(2017/11/21)
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- C- ARYL GLYCOSID DERIVATIVES, PHARMACEUTICAL COMPOSITION, PREPARATION PROCESS AND USES THEREOF
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This invention relates to a kind of C-aryl glycoside derivatives, its pharmaceutical compositions, preparation methods, and uses thereof. The preparation method comprises: method 1: in a solvent, deprotecting the acetyl protecting groups of compound 1-f in the presence of a base; method 2: 1) compound 2-g reacts with via Mitsunobu reaction; 2) deprotecting the acetyl protecting groups of compound 2-f obtained from step 1; method 3: 1) compound 2-g reacts with via nucleophilic substitution reaction; 2) deprotecting the acetyl protecting groups of compound 3-f obtained from step 1. The pharmaceutical composition comprises a kind of C-aryl glycoside derivatives; it's pharmaceutically acceptable salts and/or prodrugs thereof and excipient thereof. This invention further relates to a kind of C-aryl glycoside derivatives, it's pharmaceutically acceptable salts or pharmaceutical compositions thereof for the use in preparation of a SGLT inhibitor. The C-aryl glycoside derivatives of this invention provides a new direction for the study of SGLT inhibitors.
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Paragraph 0152; 0156; 0157
(2017/04/19)
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- Copper-catalysed cyanoalkylative cycloetherification of alkenes to 1,3-dihydroisobenzofurans: development and application to the synthesis of citalopram
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A copper-catalysed cyanoalkylative cycloetherification of alkenes was developed. Heating a solution of substituted (2-vinylphenyl)methanol in MeCN/MeOH (v/v 7/3) in the presence of a catalytic amount of copper(ii) tetrafluoroborate hydrate [Cu(BF4)2·6H2O], bathophenanthroline, K3PO4, BnOH and (tBuO)2 afforded 1,3-dihydroisobenzofurans (phthalanes) via formation of one C(sp3)-C(sp3) and one C(sp3)-O bonds. A concise synthesis of citalopram, a marketed anti-depressant drug, was accomplished by applying this novel synthetic transformation.
- Ha, Tu M.,Wang, Qian,Zhu, Jieping
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p. 11100 - 11103
(2016/09/19)
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- Compounds of the menthane series. Synthesis of unsaturated primary alcohols with the o- and p-menthane skeletons
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Precursors to terpene alcohols of the o- and p-menthane series (o-cimen-7-ol and o- and p-cimen-9-ols) were synthesized, and their reduction with lithium in ethylenediamine was studied. The reduction of o- and p-cimen-9-ols in the presence of isopropyl alcohol selectively afforded the corresponding 1,4-dihydro derivatives. Under analogous conditions, o-cimen-7-ol was converted into a mixture of unsaturated hydrocarbons. The reduction with lithium in ethylenediamine in the absence of isopropyl alcohol in all cases gave mixtures of menthene alcohols.
- Fedorov,Fedorova,Sheverdov,Pavlov,Eremkin
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p. 806 - 812
(2016/07/30)
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- Preparation of conformationally constrained α2 antagonists: The bicyclo[3.1.0]hexane approach
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The aim of the research was to discover antagonists at α2 receptor subtypes potentially more selective than known compounds. We focused on new, conformationally restricted analogues of atipamezole. The key step in the synthetic sequences leading to target compounds relied on a rhodium-catalyzed intramolecular cyclopropanation reaction, the outcome of which varied with the nature of the diazo styrene precursor. Thus, depending on the substitution pattern of the double bond and the electronic properties of the diazo precursors, the cyclopropanes 2 or 7, naphtalenes 8, or pyrazolines 17 were formed. The byproducts 8 and 17 originated from different, nonoverlapping mechanisms. Among the racemates synthesized, three compounds (1a, 22a, and 22b) showed increased selectivity for α2A vs. α2B and α2C receptor subtypes, and consequently were prepared in enantiomerically pure form. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Bonnaud, Bernard,Funes, Philippe,Jubault, Nathalie,Vacher, Bernard
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p. 3360 - 3369
(2007/10/03)
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