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
甲基(β-D-吡喃葡糖基糖醛酸)-(1-> 3)-(2-乙酰氨基-2-脱氧-6-O-磺基-β-D-吡喃半乳糖基)-(1-> 4)的合成描述了)-(β-D-吡喃葡萄糖苷)尿酸三钠盐,软骨素6-硫酸盐三糖衍生物。强调了在涉及2-脱氧-2-三氯乙酰氨基-D-半乳糖系列和D-葡萄糖醛酸衍生的受体的活化的4,6-O-亚苄基衍生物的糖基化反应中失去立体控制。通过使用苯基3,4,6-三-O-乙酰基-2-脱氧-1-硫代-2-三氯乙酰胺基-β-D-Gala吡喃果糖苷可以克服这一缺点,得到所需的β-联二糖高产率的衍生物具有出色的立体选择性。随后将其进行酸催化的甲醇分解,然后进行苄基化,并与2,3,3甲基进行缩合,生成4-三-O-苯甲酰基-1-O-三氯乙酰亚胺基-α-D-吡喃葡萄糖醛,得到预期的三糖衍生物。随后将N-三氯乙酰基转化为N-乙酰基,进行温和的酸水解,在氨基糖部分的C-6处进行选择性O-磺化,然后进行