Fortschritte bei der selektiven chemischen Synthese komplexer Oligosaccharide

Paulsen, Hans

doi:10.1002/ange.19820940304

Cited by 325 publications

(4 citation statements)

References 126 publications

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“…Some well-known pairs include BF 3 /trichloroacetimidate, NIS-TMSOTf or AgOTf/alkyl- or arylthio, , IDCP/pentenyl, , and AgOTf/halides . The wide variety of leaving groups and catalyst or promoter pairs has made it possible to carry out chemoselective glycosylations as well as multistep glycosylations to obtain complex oligosaccharides − and one-pot synthesis of tris- or tetrasaccharides. − However, it continues to be important to further broaden the scope of leaving groups and catalyst or promoter pairs.…”

Section: Introductionmentioning

confidence: 99%

Practical Glucosylations and Mannosylations Using Anomeric Benzoyloxy as a Leaving Group Activated by Sulfonium Ion

Xing

Niu

2017

ACS Omega

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One obstacle for practical glycosylations is the high cost of promoters and low-temperature equipment. This problem has been at least partially solved by using MeSCH2Cl/KI as a low-cost promoter system. MeSCH2Cl has an estimated cost of <$1/mol compared with $1741/mol for AgOTf and $633/mol for TMSOTf. This new promoter system is capable of activating various leaving groups including anomeric Cl, F, trichloroacetimidate, and acyloxy groups. Stable and easy-to-prepare anomeric benzoloxy carbohydrate donors were investigated in the glycosylations of carbohydrates, aliphatic alcohols, amino acids, steroids, and nucleoside acceptors. Most of these glycosylations were operationally simple with fast reaction rates and moderate yields of 35–79%. In addition, direct glycosylations of nucleosides using less than 2 equiv of anomeric benzoloxy donors and high stereoselective mannosylation have been achieved. From an economic point of view, this glycosylation method should be highly applicable to industrial processes.

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Section: Introductionmentioning

confidence: 99%

Practical Glucosylations and Mannosylations Using Anomeric Benzoyloxy as a Leaving Group Activated by Sulfonium Ion

Xing

Niu

2017

ACS Omega

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“…1, 5 ) are formed by intramolecular nucleophilic substitution at the anomeric center by vicinal participation of the C2 acylamino group. These are highly reactive and favor the formation of 1,2- trans -glycosides in a diastereoselective fashion [23–26]. Secondly, the C1 N -linked 1,2-glycooxazolines (Fig.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

Vangala¹,

Shinde²

2015

Beilstein J. Org. Chem.

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SummaryThe TMSOTf-mediated synthesis of β-configured spirocyclic 2-substituted-2-oxazoline ribosides was achieved using a “Ritter-like” reaction in toluene through nucleophilic addition of electron-rich nitriles to the oxacarbenium ion intermediate of 1,2;3,4-di-O-isopropylidene-β-D-psicofuranose derivatives with concomitant intramolecular trapping of the C2 hydroxymethyl group on the electrophilic nitrilium carbon. These carbohydrate-derived spirooxazolines are stable and were obtained in good yield with high stereoselectivity due to the conformational rigidity imparted by the 3,4-isopropylidene group.

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“…Significant advances include the development of the trichloroacetimidate4 and thioglycoside5 donors, as well as the armed–disarmed,6 one‐pot,7,8 and solid‐phase8,9 strategies. However, the fundamental principle for forming a glycosidic bond is the same today as in 1982,10 i.e., a glycosyl donor is activated with a promoter and coupled to a partially protected acceptor with only one free hydroxy group. Irrespective of the donor and the strategy used, this causes the synthesis of a target oligosaccharide to involve a significant number of steps, of which the majority are used for the manipulation of protecting groups.…”

Section: Introductionmentioning

confidence: 99%

Regioselective Glycosylation of Unprotected Phenyl 1‐Thioglycopyranosides with Phenylboronic Acid as a Transient Masking Group

Fenger

Madsen

2013

Eur J Org Chem

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A useful protocol is described for the regioselective glycosylation of the secondary alcohols in unprotected glycosyl acceptors. Phenyl 1‐thioglycopyranosides derived from D‐glucose, D‐galactose, D‐glucosamine, L‐rhamnose, and L‐fucose were treated with phenylboronic acid to install a temporary boronic ester, and then submitted to a Koenigs–Knorr glycosylation with perbenzoylated glucopyranosyl or galactopyranosyl bromides. Good yields for coupling to the 3‐position in glucosides and galactosides were achieved, but lower yields were obtained with the other acceptors. With phenyl 1‐thio‐β‐D‐glucopyranoside, the coupling could also be achieved with a superarmed thiogalactoside donor. The product from a glucose–glucose coupling could be subjected to a second regioselective glycosylation at the 6‐position. In the galactose series, a β(1→3)‐linked galactotriose could be prepared in good yield by two consecutive glycosylations in one pot, where a free 2‐hydroxy group ensures neighboring group participation in the second coupling.

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Fortschritte bei der selektiven chemischen Synthese komplexer Oligosaccharide

Cited by 325 publications

References 126 publications

Practical Glucosylations and Mannosylations Using Anomeric Benzoyloxy as a Leaving Group Activated by Sulfonium Ion

Practical Glucosylations and Mannosylations Using Anomeric Benzoyloxy as a Leaving Group Activated by Sulfonium Ion

Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

Regioselective Glycosylation of Unprotected Phenyl 1‐Thioglycopyranosides with Phenylboronic Acid as a Transient Masking Group

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