p-methoxyphenyl 2-O-benzyl-3-O-(2,3,4-tri-O-benzyl-α-D-rhamnopyranosyl)-4,6-O-benzylidene-β-D-galactopyranoside | 1361383-01-8

• 分子结构分类: 有机化合物 - 有机氧化合物
• 英文名称: p-methoxyphenyl 2-O-benzyl-3-O-(2,3,4-tri-O-benzyl-α-D-rhamnopyranosyl)-4,6-O-benzylidene-β-D-galactopyranoside
• CAS: 1361383-01-8
• 化学式: C₅₄H₅₆O₁₁
• 分子量: 881.032
• InChiKey: GZBVWHLVZKMZBL-WXTPBBIRSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  9.38
• 重原子数：
  65.0
• 可旋转键数：
  18.0
• 环数：
  9.0
• sp3杂化的碳原子比例：
  0.33
• 拓扑面积：
  101.53
• 氢给体数：
  0.0
• 氢受体数：
  11.0

反应信息

• 作为产物：
  描述：

  p-methoxyphenyl 2-O-benzyl-4,6-O-benzylidene-β-D-galactopyranoside 、 phenyl-2,3,4-tri-O-benzyl-1-thio-β-D-rhamnose 在 二苯基亚砜 、 2,4,6-三叔丁基嘧啶 、 三氟甲磺酸酐 作用下， 以 二氯甲烷 为溶剂， 反应 0.67h， 生成 p-methoxyphenyl 2-O-benzyl-3-O-(2,3,4-tri-O-benzyl-α-D-rhamnopyranosyl)-4,6-O-benzylidene-β-D-galactopyranoside 、 p-methoxyphenyl 2-O-benzyl-3-O-(2,3,4-tri-O-benzyl-α-D-rhamnopyranosyl)-4,6-O-benzylidene-β-D-galactopyranoside
  参考文献：
  名称：

  Stereodirecting Effect of the Pyranosyl C-5 Substituent in Glycosylation Reactions

  摘要：

  The stereodirecting effect of the glycosyl C-5 substituent has been investigated in a series of D-pyranosyl thioglycoside donors and related to their preferred positions in the intermediate H-3(4) and H-4(3) half-chair oxacarbenium ions. Computational studies showed that an axially positioned C-5 carboxylate ester can stabilize the (3)H4 half-chair oxacarbenium ion conformer by donating electron densit from its carbonyl function into the electron-poor oxacarbenium ion functionality. A similar stabilization can be achieved by a C-5 benzyloxyrnethyl group, but,the magnitude of this stabilization is significantly smaller than for the C-5 carboxylate ester. As a result, the preference of the C-5 benzyloxymethyl to occupy an axial position in the half-chair oxacarbenium ions is much reduced compared to the C-5 carboxylate ester. To minimize steric interactions, a C-5 methyl group prefers to adopt an equatorial position and therefore favors the H-4(3) half-chair oxacarbenium ion. When all pyranosyl substituents occupy their favored position in one of the two intermediate half-chair oxacarbenium ions, highly stereoselective glycosylations can be achieved as revealed by the excellent beta-selectivity of mannuronate esters and alpha-selectivity of 6-deoxygulosides.

  DOI：

  10.1021/jo900662v