T(N) 结构单元 Nα-(9-芴甲氧羰基)-O-(3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃半乳糖基)-L-丝氨酸/L-苏氨酸五氟苯基酯的合成：方案比较及副反应解析

Syntheses of T(N) building blocks Nalpha-(9-fluorenylmethoxycarbonyl)-O-(3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosyl)-L-serine/L-threonine pentafluorophenyl esters: comparison of protocols and elucidation of side reactions.

作者信息

Liu Mian, Young Victor G, Lohani Sachin, Live David, Barany George

机构信息

Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.

出版信息

Carbohydr Res. 2005 May 23;340(7):1273-85. doi: 10.1016/j.carres.2005.02.029.

DOI:10.1016/j.carres.2005.02.029

PMID:15854597

Abstract

T(N) antigen building blocks Nalpha-(9-fluorenylmethoxycarbonyl)-O-(3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosyl)-L-serine/L-threonine pentafluorophenyl ester [Fmoc-L-Ser/L-Thr(Ac3-alpha-D-GalN3)-OPfp, 13/14] have been synthesized by two different routes, which have been compared. Overall isolated yields [three or four chemical steps, and minimal intermediary purification steps] of enantiopure 13 and 14 were 5-18% and 6-10%, respectively, based on 3,4,6-tri-O-acetyl-D-galactal (1). A byproduct of the initial azidonitration reaction of the synthetic sequence, that is, N-acetyl-3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosylamine (5), has been characterized by X-ray crystallography, and shown by 1H NMR spectroscopy to form complexes with lithium bromide, lithium iodide, or sodium iodide in acetonitrile-d3. Intermediates 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosyl bromide (6) and 3,4,6-tri-O-acetyl-2-azido-2-deoxy-beta-D-galactopyranosyl chloride (7) were used to glycosylate Nalpha-(9-fluorenylmethoxycarbonyl)-L-serine/L-threonine pentafluorophenyl esters [Fmoc-L-Ser/L-Thr-OPfp, 11/12]. Previously undescribed low-level dehydration side reactions were observed at this stage; the unwanted byproducts were easily removed by column chromatography.

摘要

已通过两种不同路线合成了T(N)抗原构建块Nα-(9-芴甲氧羰基)-O-(3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃半乳糖基)-L-丝氨酸/L-苏氨酸五氟苯酯[Fmoc-L-Ser/L-Thr(Ac3-α-D-GalN3)-OPfp，13/14]，并对这两条路线进行了比较。基于3,4,6-三-O-乙酰基-D-半乳糖烯(1)，对映体纯的13和14的总分离产率[三或四个化学步骤，以及最少的中间纯化步骤]分别为5-18%和6-10%。合成序列初始叠氮硝化反应的副产物，即N-乙酰基-3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃半乳糖胺(5)，已通过X射线晶体学表征，并通过1H NMR光谱表明在氘代乙腈中与溴化锂、碘化锂或碘化钠形成配合物。中间体3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃半乳糖基溴(6)和3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-β-D-吡喃半乳糖基氯(7)用于糖基化Nα-(9-芴甲氧羰基)-L-丝氨酸/L-苏氨酸五氟苯酯[Fmoc-L-Ser/L-Thr-OPfp，11/12]。在此阶段观察到了以前未描述的低水平脱水副反应；不需要的副产物可通过柱色谱轻松去除。