90124-30-4Relevant academic research and scientific papers
Donor-Reactivity-Controlled Sialylation Reactions
Asressu, Kesatebrhan Haile,Chang, Chun-Wei,Lam, Sarah,Wang, Cheng-Chung
, p. 4525 - 4530 (2021/08/09)
Although tremendous efforts have been made for the efficient preparation of sialosides, controlling the stereochemical outcome of sialylation reaction still remains one of the most challenging tasks due to the unique chemical structure of sialic acid. We developed a new strategy to statistically analyze the stereoselectivity of sialylation reactions on six types of p-tolyl thiosialosides in NIS/TfOH system using Relative Reactivity Value (RRV) as the indicator. Analysis of the reaction mechanism showed the formation of the relatively stable glycosyl bromide and glycosyl chloride intermediates from halide- and triflate-containing promotors in the absence of an acceptor. We found that the α/β-stereoselectivity, yields, and intermediate changes were associated with their donor reactivity. These findings enable to tailor the most suitable building blocks for stereo-controlled sialylation reactions.
One-pot synthesis of sialo-containing glycosyl amino acids by use of an N-trichloroethoxycarbonyl-β-thiophenyl sialoside
Tanaka, Hiroshi,Adachi, Masaatsu,Takahashi, Takashi
, p. 849 - 862 (2007/10/03)
We describe an efficient synthesis of 2,6- and 2,3-sialyl T antigens linked to serine in a one-pot glycosylation. We first investigated the glycosidation of thiosialosides by varying the N-protecting group. Modification of the C-5 amino group of β-thiosialosides into the N-9-fluorenylmethoxycarbonyl, N-2,2,2-trichloroethoxycarbonyl (N-Troc), and N-trichloroacetyl derivatives enhanced the reactivity of these compounds towards glycosidation. Addition of a minimum amount of 3 A molecular sieves was also effective in improving the yield of α-linked sialosides. Next, we conducted one-pot syntheses of the glycosyl amino acids by using the N-Troc sialyl donor. The N-Troc derivative can be converted into the N-acetyl derivative without racemization of the amino acids. Branched-type one-pot glycosylation, initiated by regioselective glycosylation of the 3,6-dihydroxy galactoside with the N-Troc-β-thiophenyl sialoside, provided the protected 2,6-sialyl T antigen in good yield. Linear-type one-pot glycosylation, initiated by chemoselective glycosylation of galactosyl fluoride with the N-Troc-β-thiophenyl sialoside, afforded the protected 2,3-sialyl T antigen in excellent yield. Both protected glycosyl amino acids were converted into the fully deprotected 2,6- and 2,3-sialyl T antigens linked to serine in good yields.
Synthesis of a useful lauryl thioglycoside of sialic acid and its application
Matsuoka, Koji,Onaga, Tomotsune,Mori, Tomonori,Sakamoto, Jun-Ichi,Koyama, Tetsuo,Sakairi, Nobuo,Hatano, Ken,Terunuma, Daiyo
, p. 9383 - 9386 (2007/10/03)
An efficient synthesis of a useful thioglycosyl donor 2 was accomplished directly from known peracetylated sialic acid methyl ester and 1-dodecanethiol (lauryl mercaptan) in the presence of BF3-OEt2. The reactivities of the lauryl glycosides for glycosidation by means of TMSOTf as a convenient promoter were investigated, and the lauryl thioglycoside showed satisfactory activities. Further transformation of the lauryl glycoside was also attempted to give a 5-azide analogue 14 of the sialic acid, which was also reacted with a secondary alcohol in the presence of TMSOTf to give known glycoside 15 in high yield.
Dehydrative sialylation with C2-hemiketal sialyl donors
Haberman, Jannine M.,Gin, David Y.
, p. 2539 - 2541 (2007/10/03)
(Matrix presented) A new method for sialylation involving the dehydrative coupling of sialyl donors with the reagent combination of (p-nitrophenyl)(phenyl) sulfoxide and triflic anhydride is reported. This process establishes sialyl C2-hemiketals as viabl
Efficient Sialylation with Phenyltrifluoroacetimidates as Leaving Groups
Cai, Sutang,Yu, Biao
, p. 3827 - 3830 (2007/10/03)
(Matrix presented) Sialylation with N-phenyltrifluoroacetimidates as leaving groups and a catalytic amount of TMSOTf as promoter compares favorably with the previous protocols for direct sialylation and expand in essence the scope of the Schmidt glycosyla
A new C(1)-auxiliary for anomeric stereocontrol in the synthesis of alpha-sialyl glycosides.
Haberman,Gin
, p. 1665 - 1668 (2007/10/03)
The installation of the novel N,N-dimethylglycolamide ester auxiliary onto the C(1)-position of protected neuraminic acid donors allows for the exploitation of C(1)-neighboring group participation to generate sialoside conjugates with good to excellent al
Synthesis and use of glycosyl phosphites: An effective route to glycosyl phosphates, sugar nucleotides, and glycosides
Sim, Mui Mui,Kondo, Hirosato,Wong, Chi-Huey
, p. 2260 - 2267 (2007/10/02)
An efficient and convenient synthetic route to glycosyl phosphites and phosphates has been developed that uses dibenzyl N,N-diethylphosphoramidite as a phosphitylating reagent. Glycosyl phosphites and phosphates of 2-acetamido-2-deoxy-D-galactose (GalNAc) (29), 2-acetamido-2-deoxy-D-glucose (GlcNAc) (30), D-galactose (Gal) (31), D-glucose (Glc) (32), D-mannose (Man) (33), L-rhamnose (Rha) (34), L-fucose (Fuc) (35), and N-acetylneuraminic acid (NeuAc) (41) were prepared by this procedure. Compounds 29 and 30 were obtained as α anomers exclusively, whereas compounds 31, 32, and 41 were obtained as β anomers, and compounds 33 and 34, as α anomers, predominately. The phosphates are useful for the synthesis of sugar nucleotides, and the phosphites are effective glycosylation reagents.
Benzeneselenenyl triflate as an activator of thioglycosides for glycosylation reactions
Ito, Yukishige,Ogawa, Tomoya,Numata, Masaaki,Sugimoto, Mamoru
, p. 165 - 175 (2007/10/02)
A new method for the activation of thioglycosides was developed by use of benzeneselenenyl triflate (PhSeOTf), which, upon reaction with either a primary or secondary sugar HO-group, afforded O-glycosides under extremely mild reaction conditions.The reaction was applicable to various 1-thiohexosides 2-6 as well as to a 2-thioglycoside 20 derived from N-acetylneuraminic acid (NeuAc).
Glycosylation of 4,7,8,9-Tetra-O-acetyl-2-deoxy-2β,3β-epoxy-N-acetylneuraminic Acid Methyl Ester
Okamoto, Kaoru,Kondo, Tadao,Goto, Toshio
, p. 637 - 644 (2007/10/02)
Reaction of the 2β,3β-epoxyneuraminic acid derivative prepared from 2,3-dehydroneuraminic acid derivative with primary or secondary alcohol gave the corresponding glycoside(s) or ortho ester.
