- Synthesis of the Hexasaccharide Fragment of Landomycin A Using a Mild, Reagent-Controlled Approach
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The synthesis of the hexasaccharide fragment of landomycin A is reported. Using p-toluenesulfonyl chloride mediated dehydrative glycosylation, we constructed the deoxy-sugar linkages in a stereoselective fashion without the need for temporary prosthetic g
- Yalamanchili, Subbarao,Lloyd, DIna,Bennett, Clay S.
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supporting information
p. 3674 - 3677
(2019/05/17)
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- Reagent Controlled Direct Dehydrative Glycosylation with 2-Deoxy Sugars: Construction of the Saquayamycin Z Pentasaccharide
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The first synthesis of the pentasaccharide fragment of the angucycline antibiotic saquayamycin Z is described. By using our sulfonyl chloride mediated reagent controlled dehydrative glycosylation, we are able to assemble the glycosidic linkages with high
- Mizia, J. Colin,Bennett, Clay S.
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supporting information
p. 5922 - 5927
(2019/08/27)
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- Robust perfluorophenylboronic acid-catalyzed stereoselective synthesis of 2,3-unsaturated O-, C-, N- And S-linked glycosides
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A convenient protocol was developed for the synthesis of 2,3-unsaturated C-, O-, N- and S-linked glycosides (enosides) using 20 mol % perflurophenylboronic acid catalyst via Ferrier rearrangement. Using this protocol, D-glucals and L-rhamnals reacted with various C-, O-, N- and S-nucleophiles to give a wide range of glycosides in up to 98% yields with mainly α-anomeric selectivity. The perflurophenylboronic acid successfully catalyzed a wide range of substrates (both glucals and nucleophiles) under very mild reaction conditions.
- Tatina, Madhu Babu,Mengxin, Xia,Peilin, Rao,Judeh, Zaher M. A.
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supporting information
p. 1275 - 1280
(2019/07/08)
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- Magnetic core-shell Fe3O4@C-SO3H as an efficient and renewable 'Green catalyst' for the synthesis of O-2,3-unsaturated Glycopyra-nosides
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A magnetic core-shell solid-acid catalyst Fe3O4@C-SO3H was studied for synthesis of O-2,3-unsaturated glycosides through Ferrier rearrangement. The donors include 3,4,6-tri-O-acetyl-D-glucal and 3,4-di-O-acetyl-L-rhamnal. The acceptors consist of primary alcohols, secondary alcohols, tert-butanol, unsaturated alcohols, halogenated alcohol, sterol, sugars, and phenols. O-2,3-Unsaturated glycosides were obtained rapidly (5:1 to 19:1). Moreover, the catalyst can be easily separated from the reaction with an external magnetic force and reused for a minimum of five times without any significant decrease in the yields of the products after every recycle, suggesting it a promising green catalyst in 2,3-unsaturated glycosides syntheses.
- Sun, Guosheng,Qiu, Saifeng,Ding, Zekun,Chen, Heshan,Zhou, Jiafen,Wang, Zhongfu,Zhang, Jianbo
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supporting information
p. 347 - 352
(2017/02/10)
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- Y(OTf)3 as a highly efficient catalyst in Ferrier Rearrangement for the synthesis of O- and S-2,3-unsaturated glycopyranosides
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By using Y(OTf)3 as the catalyst, a series of 2,3-unsaturated-glucosides have been synthesized from 3,4,6-tri-O-acetyl-d-glucal, 3,4-di-O-acetyl-l-rhamnal, and 3,4,6-tri-O-benzyl-d-glucal under mild reaction conditions in good yields with high anomeric selectivities. It was found that, in this reaction, 3,4,6-tri-O-benzyl-d-glucal behaved differently from the other two glucals when it was reacted with phenol, O-benzyl glucoside instead of O-phenyl glucoside formed as the sole product. An explanation is given for this phenomenon.
- Chen, Peiran,Li, Shan
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supporting information
p. 5813 - 5816
(2015/02/19)
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- New chiral pool approach to anthracyclinones. The stereoselective synthesis of idarubicinone
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In the present work, a new chiral pool approach has been developed for the synthesis of anthracyclinones. Thus, enone 8, readily available from L-rhamnose, has been converted via addition of 2,5-dimethoxybenzyllithium to the carbonyl group and a series of six reactions into a suitably protected aldehyde 21. The SnCl4-promoted stereospecific cyclization of the latter afforded enantiopure key intermediate 22. Silylation of benzylic hydroxyl of 21 followed by anodic oxidation and selective hydrolysis gave ketoacetals 25 and 26 to which 3-cyano-1(3H)-isobenzofuranone 27 was annelated. Removal of the isopropylidene group in the resulting 28, subsequent oxidation of the C13 hydroxyl and full deprotection led to idarubicinone (4).
- Achmatowicz, Osman,Szechner, Barbara
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p. 2398 - 2404
(2007/10/03)
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- Studies related to the carbohydrate sectors of esperamicin and calicheamicin: Definition of the stability limits of the esperamicin domain and fashioning of a glycosyl donor from the calicheamicin domain
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The core trisaccharide regions of esperamicin and the aryltetrasaccharide region of calicheamicin have been synthesized. The minimum protection modalities necessary to stabilize structures against rearrangement to an isomeric azafuranose series were ascertained (see compounds 12 and 65). Deprotection of the 2-(trimethylsilyl)-ethoxycarbonyl carbamate from 65 led to azafuranose 14 characterized as methyl glycoside 15. Using this insight, it was possible to fashion, for the first time, a pre-glycosyl donor (see compound 128) corresponding to the complete arylsaccharide sector of calicheamicin γ1I at the oxidation level of the domain. Among the key assembly strategies were the conversion of α-thiophenylpseudoglycals to allal derivatives (see 44 → 45); the interfacing of epoxide-mediated glycosylation with iodoglycosylation (see 30 → 47 → 48); the synthesis of hydroxylamine glycosides via inflate displacement (see 61 + 91 → 101); and a new route to p-hydroxybenzonitriles (see formation of 86).
- Halcomb, Randall L.,Boyer, Serge H.,Wittman, Mark D.,Olson, Steven H.,Denhart, Derek J.,Liu, Kevin K. C.,Danishefsky, Samuel J.
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p. 5720 - 5749
(2007/10/02)
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- SYNTHESIS OF ISOMERIC BENZYL 6-DEOXY-α-L-TALO- AND α-L-GULOPYRANOSIDES
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Synthesis of benzyl 2,3,4-tri-O-acetyl-6-deoxy-α-L-talopyranoside (6) and its α-L-gulo isomer 7 was performed by a five-step sequence starting from L-rhamnal 1.The L-talo isomer was proved to be identical with the component of O-antigenic polysaccharide o
- Banaszek, Anna
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p. 285 - 292
(2007/10/02)
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- A convergent synthesis of optically active aspyrone
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Aspyrone (1) was elaborated in an optically pure form by the key reaction involving a nucleophilic addition of δ-lactone enolate to 2-tosyloxyaldehyde and a subsequent in situ formation of epoxide.
- Sugiyama,Murayama,Yamashita
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p. 7343 - 7344
(2007/10/02)
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