The use of 2-deoxy-2-trichloroacetamido-?-glucopyranose derivatives in syntheses of hyaluronic acid-related tetra-, hexa-, and octa-saccharides having a methyl β-?-glucopyranosiduronic acid at the reducing end
Efficient and stereocontrolled synthesis of size-defined hyaluronan oligomers is described for the first time starting from natural chondroitin polymer. Semisynthesis from chondroitin polymer afforded a disaccharide fragment that was used as starting material for the efficient preparation of a protected hyaluronicaciddisaccharidebuildingblock. Selective inversion of configuration at C-4 of the
Transformation of the (2-nitrophenyl)acetyl protecting group in the presence of trichloroacetonitrile and 1,8-diazabicyclo[5,4,0]-undec-7-ene
作者:Jean-Claude Jacquinet
DOI:10.1016/j.carres.2012.11.003
日期:2013.1
trichloroacetonitrile in the presence of 1,8-diazabicyclo[5,4,0]-undec-7-ene, the (2-nitrophenyl)acetylprotectinggroup (NPAc) was partially transformed into mono-(NPClAc) and dichlorinated (NPCl(2)Ac) species, but no chlorination occurred in the presence of solid potassium carbonate. The monochlorinated NPClAc group, which is suitable for use in glycosylation reaction, can be selectively removed by treatment
Unexpected stereochemical outcome of activated 4,6-O-benzylidene derivatives of the 2-deoxy-2-trichloroacetamido-d-galacto series in glycosylation reactions during the synthesis of a chondroitin 6-sulfate trisaccharide methyl glycoside
作者:Frédéric Bélot、Jean-Claude Jacquinet
DOI:10.1016/s0008-6215(99)00322-5
日期:2000.4
disaccharide derivative in high yield with an excellent stereoselectivity. This later was submitted to acid-catalyzed methanolysis, followed by benzylidenation, and condensed with methyl 2,3,4-tri-O-benzoyl-1-O-trichloroacetimidoyl-alpha-D-glucopyran uronate to afford the expected trisaccharide derivative. Subsequent transformation of the N-trichloroacetyl group into N-acetyl, mild acid hydrolysis, selective
Unexpected loss of stereoselectivity in glycosylation reactions during the synthesis of chondroitin sulfate oligosaccharides
作者:Teresa Mena-Barragán、José L de Paz、Pedro M Nieto
DOI:10.3762/bjoc.15.14
日期:——
results, together with those obtained from experiments employing model monosaccharide buildingblocks, highlight the impact of the glycosyl acceptor structure on the stereoselectivity of glycosylation reactions. Our study provides useful data about the substitution pattern of GlcA units for the efficient synthesis of CS oligomers.