55676-46-5Relevant academic research and scientific papers
A highly stereocontrolled synthesis of 1β,1β-linked acetylated oligosaccharides via orthoester formation-rearrangement
Wang,Kong
, p. 1361 - 1364 (1999)
1β,1β- Linked acetylated di-, tri-, and tetrasaccharides were synthesized in satisfactory yields and good stereoselectivities by a new method - orthoester formation and rearrangement under mild conditions.
Glycosyl Fluorides as Intermediates in BF3·OEt2-Promoted Glycosylation with Trichloroacetimidates
Nielsen, Michael M.,Stougaard, Bolette A.,Bols, Mikael,Glibstrup, Emil,Pedersen, Christian M.
supporting information, p. 1281 - 1284 (2017/03/17)
Glycosyl fluorides have been found to be important intermediates in glycosylations with trichloroacetimidate donors and BF3·OEt2 activation (0.2–1 equiv.). Low-temperature NMR spectroscopy experiments revealed that the α-trichloroacetimidate was transformed into the glycosyl fluoride with inversion of stereochemistry, whereas the β anomer was not. A concerted mechanism was suggested for the stereospecific formation of glycosyl fluorides, which is not accounted for in the classic mechanism.
Synthesis of branched dithiotrisaccharides via ring-opening reaction of sugar thiiranes
Repetto, Evangelina,Manzano, Veronica E.,Uhrig, Maria Laura,Varela, Oscar
, p. 253 - 265 (2012/02/14)
Satisfactory procedures are described for the synthesis of 5,6- and 3,4-thiirane derivatives from the respective hexofuranose or hexopyranose epoxide precursors. The controlled ring-opening reaction of thiiranes by 1-thioaldoses was successfully accomplished to afford, regio- and stereoselectively, β-S-(1→4)-3,4-dithiodisaccharides. For instance, the regioselective attack of per-O-acetyl-1-thioglucose (16) to C-4 of 2-propyl 2,6-di-O-acetyl-3,4-epithio-α-d-galactopyranoside (14) gave the derivative of Glcp-β-S-(1→4)-3,4-dithioGlcp-O-iPr (17). This thiodisaccharide was accompanied by the (1→3)-disulfide 18, formed between 16 and 17, and the symmetric (3→3)-disulfide 19, which resulted from the oxidative dimerization of 17. However, the S-acetyl derivative of 17 could be obtained in good yield (62%) by LiAlH4 reduction of the crude mixture 17-19, followed by acetylation. The same sequence of reactions starting from 14 and the 1-thiolate of Galp afforded the per-O,S-acetyl derivative of Galp-β-S-(1→4)-3,4-dithio-α-d-Glcp-O-iPr (23), which was selectively S-deacetylated to give 25. The dithiosaccharides 17 and 25 are 3,4-di-S-analogues of derivatives of the natural disaccharides cellobiose and lactose, respectively. The ring-opening reaction of 5,6-epithiohexofuranoses of d-galacto (8) or l-altro (11) configuration with 1-thioaldoses was also regio- and stereoselective to give the respective β-S-(1→6)-linked 5,6-dithiodisaccharides 26 or 29 in excellent yields. Glycosylation of the free thiol group of 17, 25, or 26, using trichloroacetimidates as glycosyl donors, led to the corresponding branched dithiotrisaccharides. Some of them are sulfur analogues of derivatives of branched trisaccharides found in natural polysaccharides.
Novel Water-Soluble Bisphosphinite Chiral Ligands Derived from α,α- And β,β-Trehalose. Application to Asymmetric Hydrogenation of Dehydroamino Acids and Their Esters in Water or an Aqueous/ Organic Biphasic Medium
Yonehara, Koji,Hashizume, Tomohiro,Mori, Kenji,Ohe, Kouichi,Uemura, Sakae
, p. 5593 - 5598 (2007/10/03)
Novel 2,3:4,6-di-O-isopropylidene-α-D-glucopyranosyl-(1,1)-4,6-O-isopropylidene- 2,3-di-O-diphenylphosphino-α-D-glucopyranoside (2), 2,3:4,6-di-O-cyclohexylidene-α-D-glucopyranosyl-(1,1)-4,6-O- cyclohexylidene-2,3-di-O-diphenylphosphino-α-D-glucopyranoside (4), and 2,3:4,6-di-O-cyclohexylidene-β-D-glucopyranosyl-(1,1)-4,6-O- cyclohexylidene-2,3-di-O-diphenylphosphino-β-D-glucopyranoside (11) were prepared from the corresponding α,α- or β,β-trehalose. The ligands were transformed into cationic Rh complexes, such as [Rh(α-D-glucopyranosyl-(1,1)-2,3-di-O-diphenylphosphino-α-D- glucopyranoside)(cod)]BF4 (3) and [Rh(β-D-glucopyranosyl-(1,1)-2,3-di-O-diphenylphosphino-β-D- glucopyranoside)(cod)]BF4 (12) bearing free hydroxy groups. These complexes were soluble in water and were efficient catalysts for the asymmetric hydrogenation of dehydroamino acids and their esters in water or an aqueous/organic biphasic medium with high enantioselectivity (up to 99.9% ee). Aqueous biphasic systems offer an easy separation of the aqueous catalyst phase from the product phase and allow recycling of the catalyst phase without the loss of enantioselectivity.
A NOVEL OBSERVATION ON KOENIGS-KNORR CONDENSATION OF 2,3,4,6-TETRA-O-ACETYL-α-D-GLUCOPYRANOSYL BROMIDE WITH METHYL 4,6-O-BENZYLIDENE-α-D-GLUCOPYRANOSIDE
Temeriusz, Andrzej,Piekarska, Boguslawa,Radomski, Jan,Stepinski, Janusz
, p. 141 - 147 (2007/10/02)
As a result of condensation between methyl 4,6-O-benzylidene-α-D-glucopyranoside and bromo-2,3,4,6-tetra-O-acetyl-α-D-glucopyranose in 1,2-dichloroethane in presence of silver carbonate, after removal of functional groups, the following substances were ob
