methyl 2,3-di-O-benzyl-4-O-[methyl (4-O-benzyl-2,3-O-isopropylidene-α-D-mannopyranosyluronate)]-α-D-mannopyranosyluronate | 1158840-69-7

• 分子结构分类: 有机化合物 - 有机氧化合物
• 英文名称: methyl 2,3-di-O-benzyl-4-O-[methyl (4-O-benzyl-2,3-O-isopropylidene-α-D-mannopyranosyluronate)]-α-D-mannopyranosyluronate
• CAS: 1158840-69-7
• 化学式: C₃₉H₄₆O₁₃
• 分子量: 722.786
• InChiKey: MQJRPZXXEZDTPS-HKMCTADRSA-N

物化性质

• 沸点：
  746.8±60.0 °C(predicted)
• 密度：
  1.29±0.1 g/cm3(Temp: 20 °C; Press: 760 Torr)(predicted)

计算性质

• 辛醇/水分配系数(LogP)：
  4.09
• 重原子数：
  52.0
• 可旋转键数：
  14.0
• 环数：
  6.0
• sp3杂化的碳原子比例：
  0.49
• 拓扑面积：
  135.67
• 氢给体数：
  0.0
• 氢受体数：
  13.0

反应信息

• 作为产物：
  描述：

  methyl (phenyl 4-O-benzyl-2,3-O-isopropylidene-1-thio-β-D-mannopyranosyluronate) 、 methyl (methyl 2,3-di-O-benzyl-α-D-mannopyranosyluronate) 在 三氟甲磺酸酐 、 二苯基亚砜 、 2,4,6-三叔丁基嘧啶 作用下， 以 二氯甲烷 为溶剂， 反应 0.25h， 以20%的产率得到methyl 2,3-di-O-benzyl-4-O-[methyl (4-O-benzyl-2,3-O-isopropylidene-α-D-mannopyranosyluronate)]-α-D-mannopyranosyluronate
  参考文献：
  名称：

  Stereoselectivity of glycosylations of conformationally restricted mannuronate esters

  摘要：

  Glycosidation of conformationally unrestricted mannuronate ester donors proceeds in a highly P-selective fashion, whereas condensations of mannuronate ester donors, which are con formationally constrained by a 3,4-butanedimethylacetal or a 2,3-isopropylidene function, provide a-selective products. We hypothesize that the difference in stereochemical outcome of these condensations results from the different conformations of the product forming oxacarbenium intermediate. The formation of the beta-linked products from the flexible mannuronates is thought to originate from the most favorable H-3(4) oxacarbenium ion, which is not accessible from the conformationally restrained donors. Although an a-triflate intermediate is formed upon activation of the 3,4-butanedimethylacetal protected mannuronate ester thio donor, this is not the product forming intermediate. The anomeric triflate serves as a reservoir for the H-4(3) oxacarbenium ion, which is glycosidated to provide the a-linked mannuronates. (C) 2009 Elsevier Ltd. All rights reserved.

  DOI：

  10.1016/j.tet.2009.02.067