Unprotected Carbohydrates as Starting Material in Chemical Synthesis: Not Just a Challenge but an Opportunity

Saloranta, Tiina; Leino, Reko

doi:10.1055/s-0034-1379979

Cited by 31 publications

(18 citation statements)

References 19 publications

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“…31 But there are some tools which helpto utilize carbohydrates as aldehydes or ketones to a full extent, which will be discussed in this article.…”

Section: Scheme 5 Catalyst-free Aldol Additions Of Aldehydes With Ethmentioning

confidence: 99%

The long underestimated carbonyl function of carbohydrates – an organocatalyzed shot into carbohydrate chemistry

Mahrwald

2015

Chem. Commun.

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The aggressive and strong development of organocatalysis provides several protocols for the convenient utilization of the carbonyl function of unprotected carbohydrates in C-C-bond formation processes. These amine-catalyzed mechanisms enable multiple cascade-protocols for the synthesis of a wide range of carbohydrate-derived compound classes. Several, only slightly different protocols, have been developed for the application of 1,3-dicarbonyl compounds in the stereoselective chain-elongation of unprotected carbohydrates and the synthesis of highly functionalized C-glycosides of defined configuration. In addition, C-glycosides can also be accessed by amine-catalyzed reactions with methyl ketones. By a one-pot cascade reaction of isocyanides with unprotected aldoses and amino acids access to defined configured glycopeptide mimetics is achieved. Depending on the reaction conditions different origins to control the installation of configuration during the bond-formation process were observed.

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“…31 But there are some tools which helpto utilize carbohydrates as aldehydes or ketones to a full extent, which will be discussed in this article.…”

Section: Scheme 5 Catalyst-free Aldol Additions Of Aldehydes With Ethmentioning

confidence: 99%

The long underestimated carbonyl function of carbohydrates – an organocatalyzed shot into carbohydrate chemistry

Mahrwald

2015

Chem. Commun.

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“…4,5 However, with the exception of some partial reduction methods, [6][7][8] carbohydrate biomass treatment often results in the loss of functional groups and chiral information, and it remains very challenging to selectively remove one or more hydroxyl groups from a polyol, without resorting to extensive protecting group manipulations. 9,10 For this reason, the range of more complex targets retaining stereochemical information from biomass sugars prepared via succinct methods avoiding extensive protection-deprotection steps has remained limited.…”

Section: Introductionmentioning

confidence: 99%

Functionalised tetrahydrofuran fragments from carbohydrates or sugar beet pulp biomass

et al. 2019

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Carbohydrate biomass represents a potentially valuable sustainable source of raw materials for chemical synthesis, but for many applications, selective deoxygenation/dehydration of the sugars present is necessary to access compounds with useful chemical and physical properties. Selective dehydration of pentose sugars to give tetrahydrofurans can be achieved by treatment of the corresponding N,N-dimethylhydrazones under acidic or basic conditions, with the two approaches showing complementary stereoselectivity. The dehydration process is readily scalable and the THF hydrazones derived from arabinose, ribose, xylose and rhamnose were converted into a range of useful fragments containing primary alcohol, ketone, carboxylic acid or amine functional groups. These compounds have potentially useful physiochemical properties making them suitable for incorporation into fragment/lead generation libraries for medicinal chemistry. It was also shown that L-arabinose hydrazone could be obtained selectively from a crude sample of hydrolysed sugar beet pulp. † Electronic supplementary information (ESI) available: Procedures for the preparation of all compounds, together with characterisation data and X-ray crystallographic data. CCDC 1877937 and 1877938. For ESI and crystallographic data in CIF or other electronic format see Scheme 4 Proposed mechanism for the basic cyclisation of L-arabinose hydrazone 1a and D-ribose hydrazone 1b.Scheme 5 Base mediated (a) cyclic carbonate 6a formation, (b) cyclisation of 7a. Green Chemistry PaperThis journal is Scheme 10 Synthesis of carboxylic acid 10a from (a) triol 9a and (b) hydrate 12a.∥ Tables of selected crystallographic data for 9b and 13-Br can be found in the ESI. † CCDC 1877937 and 1877938 contain the supplementary crystallographic data for compounds 9b and 13-Br respectively. ¶ The selectivity of the acetal protection was confirmed by obtaining an X-ray crystal structure of 13-Br,∥ an analogue of 13 prepared from 4-bromobenzaldehyde (see ESI † for full details). Green Chemistry PaperThis journal is

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“…More expedient chemical and enzymatic methods to access glycosides is an ongoing area of research and one that could have implications that extend far beyond a synthetic chemist’s laboratory [2–4]. Glycosylation is a coupling reaction that takes place at the anomeric position (C1–OH) of a saccharide, termed donor, and another molecule, termed the acceptor, with the product of the reaction termed glycoside.…”

Section: Introductionmentioning

confidence: 99%

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

Downey

Hocek

2017

Beilstein J. Org. Chem.

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Glycosylation is an immensely important biological process and one that is highly controlled and very efficient in nature. However, in a chemical laboratory the process is much more challenging and usually requires the extensive use of protecting groups to squelch reactivity at undesired reactive moieties. Nonetheless, by taking advantage of the differential reactivity of the anomeric center, a selective activation at this position is possible. As a result, protecting group-free strategies to effect glycosylations are available thanks to the tremendous efforts of many research groups. In this review, we showcase the methods available for the selective activation of the anomeric center on the glycosyl donor and the mechanisms by which the glycosylation reactions take place to illustrate the power these techniques.

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Unprotected Carbohydrates as Starting Material in Chemical Synthesis: Not Just a Challenge but an Opportunity

Cited by 31 publications

References 19 publications

The long underestimated carbonyl function of carbohydrates – an organocatalyzed shot into carbohydrate chemistry

The long underestimated carbonyl function of carbohydrates – an organocatalyzed shot into carbohydrate chemistry

Functionalised tetrahydrofuran fragments from carbohydrates or sugar beet pulp biomass

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

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