- Catalyst recognition of cis-1,2-diols enables site-selective functionalization of complex molecules
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Carbohydrates and natural products serve essential roles in nature, and also provide core scaffolds for pharmaceutical agents and vaccines. However, the inherent complexity of these molecules imposes significant synthetic hurdles for their selective functionalization and derivatization. Nature has, in part, addressed these issues by employing enzymes that are able to orient and activate substrates within a chiral pocket, which increases dramatically both the rate and selectivity of organic transformations. In this article we show that similar proximity effects can be utilized in the context of synthetic catalysts to achieve general and predictable site-selective functionalization of complex molecules. Unlike enzymes, our catalysts apply a single reversible covalent bond to recognize and bind to specific functional group displays within substrates. By combining this unique binding selectivity and asymmetric catalysis, we are able to modify the less reactive axial positions within monosaccharides and natural products.
- Sun, Xixi,Lee, Hyelee,Lee, Sunggi,Tan, Kian L.
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p. 790 - 795
(2013/09/23)
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- Regioselective benzoylation of glycopyranosides by benzoyl chloride in the presence of MoO2(acac)2
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Benzoylation of methyl and benzyl glycopyranosides by benzoyl chloride in the presence of MoO2(acac)2 as a catalyst resulted in 3-benzoates with good yield and high regioselectivity. Simple synthesis of the monobenzoates of some glyc
- Evtushenko
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experimental part
p. 369 - 378
(2012/06/04)
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- Regioselective monoacetylation of methyl pyranosides of pentoses and 6-deoxyhexoses by acetic anhydride in the presence of MoCl5
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Convenient regioselective syntheses of 3-acetates of methyl pyranosides of α-L-rhamnose, α- and β-L-arabinose, α-D-fucose, α-D-lyxose, and β-D-ribose with good yields have been attained using MoCl5 as catalyst. Methyl β-L-rhamnopyranoside under this conditions gave 2-acetate. Copyright Taylor & Francis Group, LLC.
- Evtushenko, Evgeny V.
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p. 1593 - 1599
(2007/10/03)
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- Synthetic Cyclic Oligosaccharides - Syntheses and Structural Properties of a Cyclo(1->4)-α-L-rhamnopyranosyl-(1->4)-α-D-mannopyranosyl>trioside and -tetraoside
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An efficient polycondensation-cyclization approach to the synthesis of cyclodextrin analogues is demonstrated by the preparation of cyclohexaoside 1 and cyclooctaoside 2.The key intermediate, disaccharide 3, bearing the cyanoethylidene group as a glycosyl
- Ashton, Peter R.,Brown, Christopher L.,Menzer, Stephan,Nepogodiev, Sergey A.,Stoddart, J. Fraser,Williams, David J.
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p. 580 - 591
(2007/10/03)
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- Enzymatic esterification and de-esterification of carbohydrates: synthesis of a naturally occurring rhamnopyranoside of p-hydroxybenzaldehyde and a systematic investigation of lipase-catalysed acylation of selected arylpyranosides
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The regiocontrolled esterification and de-esterification of mono- and di-saccharides is reviewed.New results involving the enzyme-catalysed regioselective acylation of ribo-110, arabino-112, 119, xylo-111, and rhamnopyranosides 116, 118 (as well as two ar
- Bashir, Nazir B.,Phythian, Sara J.,Reason, Andrew J.,Roberts, Stanley M.
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p. 2203 - 2222
(2007/10/02)
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- SYNTHESIS OF 1,2-trans-DISACCHARIDES via SUGAR THIO-ORTHOESTERS
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The reaction of sugar 1,2-thio-orthoesters in the D-gluco, D-galacto, D-manno, and L-rhamno series with primary and secondary trityl ethers of monosaccharides, in the presence of triphenylmethylium perchlorate as catalyst, affords, stereospecifically, derivatives of 1,2-trans-disaccharides in good yields. 4-Trityl ethers of benzyl 2-acetamido-3,6-di-O-acetyl-2-deoxy-α-D-glucopyranoside and methyl 2,3,6-tri-O-benzoyl-α-D-galactopyranoside exhibit low reactivity in glycosylation by thio-ortho-esters.A reaction scheme for the glycosylation is discussed.
- Backinowsky, Leon V.,Tsvetkov, Yury E.,Balan, Nikolay F.,Byramova, Narguiz E.,Kochetkov, Nikolay K.
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p. 209 - 222
(2007/10/02)
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