Total synthesis of sialosylcerebroside, GM4

Numata, Masaaki; SUGIMOTO, M.; Koike, Katsuya; Ogawa, Tomoya

doi:10.1016/0008-6215(87)80182-9

Cited by 126 publications

(32 citation statements)

References 27 publications

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“…14,15 The disadvantage in their use is the production of trichloroacetamide (MW = 144) as a byproduct. In a preliminary survey, we found that acetate was an adequate leaving group for the [COP-OAc] 2 -catalyzed cyclization of phenolic ( E )-allylic acetate 19 to form 2-vinylchromane (Table 3).…”

Section: Resultsmentioning

confidence: 99%

Palladium(II)-Catalyzed Enantioselective Synthesis of 2-Vinyl Oxygen Heterocycles

et al. 2012

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2-Vinylchromanes (1), 2-vinyl-1,4-benzodioxanes (2), and 2,3-dihydro-2-vinyl-2H-1,4-benzoxazines (3) can be prepared in high yields (90–98%) and excellent enantiomeric purities (87–98% ee) by [COP-OAc]2-catalyzed cyclization of phenolic (E)-allylic trichloroacetimidate precursors. Deuterium-labeling and computational experiments are consistent with these cyclization reactions taking place by an anti-oxypalladation/syn-deoxypalladation mechanism. 2-Vinylchromanes can be prepared also in good yields and high enantiomeric purities from analogous (E)-allylic acetate precursors, which constitutes the first report that acetate is a competent leaving group in COP-catalyzed enantioselective SN2′ substitution reactions.

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Section: Resultsmentioning

confidence: 99%

Palladium(II)-Catalyzed Enantioselective Synthesis of 2-Vinyl Oxygen Heterocycles

et al. 2012

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“…19) When ether was used as the solvent, decrement of both a-selectivity and yield was observed (entry 3). Finally, the glycosylation of 1b with 5c promoted by NIS-TfOH in CH 3 CN at Ϫ40°C afforded a 4 : 1 mixture of the known a and b Neu5Ac-(2→3)-galactoside 6c 20) in 37% (entry 4).…”

Section: Resultsmentioning

confidence: 99%

Preparation of 4-Pentenoic Acid Ester of Neu5Ac and 4-Pentenyl Glycoside of Neu5Ac and Their Application to Glycosylation

et al. 2005

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N-Acetylneuraminic acids (Neu5Ac), sialic acids are most frequently found as a-glycosidically linked terminal residues of glycoproteins and glycolipids. There are a wide range of biological properties endowed by sialic acids on natural glycoconjugate structure and function, often involved in important cell surface communications and infection processes. 1-3)The development of the efficient method of O-sialylation has been a challenging task in the field of sialic acid chemistry. 4,5) Fraser-Reid and his co-workers introduced a 4-pentenyl group as a new and effective leaving group at the anomeric center of the glycosyl donor.6) The attractiveness of 4-pentenyl glycosides is enhanced by the fact that they can be applied to the armed/disarmed methodology of oligosaccharide synthesis.7) 4-Pentenyl glycosides are of interest for studying various biological and physiological phenomena of carbohydrates.8) To the best of our knowledge, there has been no report on the synthesis of 4-pentenoic acid ester of Neu5Ac (1a). A few reports 9,10) on the synthesis of 4-pentenyl glycoside of Neu5Ac (1b) have been reported, however application of 1b to O-sialylation has not been studied. As a part of our program aimed at the development of new O-sialylation, 11,12) we are interested in finding out whether 1a, b would be suitable for stereoselective O-sialylation. This paper describes the synthesis of 1a, b and their application to O-sialylation. Results and DiscussionWe first focused on an efficient synthesis of 1a having 4-pentenoyloxy group at the 2-position of Neu5Ac as a leaving group. Treatment of per-O-acetylated Neu5Ac 2 with hydrogen chloride in AcCl-AcOH (1 : 1) gave 2-chloro derivative 3 in a quantitative yield. Compound 3 was treated with silver carbonate in acetone-H 2 O (9 : 1) to afford 2-hydroxy derivative 4 13) in 88% yield. Acylation of 4 was achieved by 4-pentenoic anhydride and pyridine and N,N-dimethylaminopyridine (DMAP) in CH 2 Cl 2 to give 1a in a quantitative yield as an anomeric mixture with b-anomer as the major product (Chart 1). Next, we focused on a search for an efficient method of synthesizing 1b. When silver salicylate was used as a promoter in the presence of 4-penten-1-ol in CH 2 Cl 2 , 1b was obtained in 80% yield.9) The best result was obtained when the reaction was performed by Koenigs-Knorr condi- * To whom correspondence should be addressed. e-mail: ikeda@u-shizuoka-ken.ac. Novel sialosyl donors, 4-pentenoic acid ester of N-acetylneuraminic acids (Neu5Ac) (1a) and 4-pentenyl glycoside of Neu5Ac (1b) were successfully prepared from the corresponding per-O-acetylated 2-hydroxy and 2-chloro derivatives of Neu5Ac, respectively and applied to the synthesis of O-sialosides.

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“…Deblocking of the 3-O-chloroacetyl group in 22 was achieved with thiourea and the resulting alcohol 23 was converted into ester 24 by acetylation. Selective removal of the 2-(trimethylsilyl)ethyl group in 24 was achieved with trifluoroacetic acid in CH 2 Cl 2 , and treatment with CCl 3 CN in the presence of 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) 23) to provide the corresponding a-trichloroacetimidate 25 in 74% yield. Tetrasaccharide derivative 26 was synthesized by coupling of donor 25 with disaccharide acceptor 13 in 83% yield.…”

Section: Synthetic Studies On Glycosphingolipids From Protostomia Phymentioning

confidence: 99%

Synthetic Studies on Glycosphingolipids from Protostomia Phyla: Synthesis of Glycosphingolipids from the Parasite Schistosoma mansoni

Kanaya

Yagi

Schweizer

et al. 2010

CHEMICAL & PHARMACEUTICAL BULLETIN

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Total synthesis of sialosylcerebroside, GM4

Cited by 126 publications

References 27 publications

Palladium(II)-Catalyzed Enantioselective Synthesis of 2-Vinyl Oxygen Heterocycles

Palladium(II)-Catalyzed Enantioselective Synthesis of 2-Vinyl Oxygen Heterocycles

Preparation of 4-Pentenoic Acid Ester of Neu5Ac and 4-Pentenyl Glycoside of Neu5Ac and Their Application to Glycosylation

Synthetic Studies on Glycosphingolipids from Protostomia Phyla: Synthesis of Glycosphingolipids from the Parasite Schistosoma mansoni

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