methyl (2S,3S,4S,5S,6S)-3-acetyloxy-4,5-bis(phenylmethoxy)-6-phenylsulfanyloxane-2-carboxylate | 1320281-30-8

• 分子结构分类: 有机化合物 - 有机氧化合物
• 英文名称: methyl (2S,3S,4S,5S,6S)-3-acetyloxy-4,5-bis(phenylmethoxy)-6-phenylsulfanyloxane-2-carboxylate
• CAS: 1320281-30-8
• 化学式: C₂₉H₃₀O₇S
• 分子量: 522.619
• InChiKey: WPMQRFCQIBPVEH-RRUDZPKISA-N

计算性质

• 辛醇/水分配系数(LogP)：
  5
• 重原子数：
  37
• 可旋转键数：
  12
• 环数：
  4.0
• sp3杂化的碳原子比例：
  0.31
• 拓扑面积：
  106
• 氢给体数：
  0
• 氢受体数：
  8

反应信息

• 作为反应物：
  描述：

  methyl (2S,3S,4S,5S,6S)-3-acetyloxy-4,5-bis(phenylmethoxy)-6-phenylsulfanyloxane-2-carboxylate 在 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 0.5h， 生成 methyl (4-acetyl-2,3-O-benzyl-1-trifluoromethylsulfonyl-α-mannopyranosyluronate)
  参考文献：
  名称：

  Equatorial Anomeric Triflates from Mannuronic Acid Esters

  摘要：

  Activation of mannuronic acid esters leads to a conformational mixture of alpha-anomeric triflates, in which the equatorial triflate (C-1(4), chair) is formed preferentially. This unexpected intermediate clearly opposes the anomeric effect and is mainly stabilized by the electron-withdrawing carboxylate function at C-5. Because the anomeric center carries a significant positive charge, the C-1(4), mannopyral chair approximates the favored H-3(4), half-chair oxacarbenium ion conformation. The excellent B-selectivity in glycosytations of mannuronates is postulated to originate from the cooperative action of the triflate counterion and the (stereo)etectronic effects governing oxacarbenium ion stabilization in the transition state leading to the 1,2-cis product.

  DOI：

  10.1021/ja905008p

文献信息

• The impact of oxacarbenium ion conformers on the stereochemical outcome of glycosylations
  作者：Marthe T.C. Walvoort、Jasper Dinkelaar、Leendert J. van den Bos、Gerrit Lodder、Herman S. Overkleeft、Jeroen D.C. Codée、Gijsbert A. van der Marel

  DOI：10.1016/j.carres.2010.02.027

  日期：2010.7

  The search for stereoselective glycosylation reactions has occupied synthetic carbohydrate chemists for decades. Traditionally, most attention has been focused on controlling the S(N)2-like substitution of anomeric leaving groups as highlighted by Lemieux's in situ anomerization protocol and by the discovery of anomeric triflates as reactive intermediates in the stereoselective formation of beta-mannosides

  立体选择性糖基化反应的研究已经占据了合成碳水化合物化学家的数十年。传统上，大多数注意力都集中在控制异头离去基团的S（N）2取代上，如Lemieux的原位异构化方案和发现异头三氟甲磺酸酯作为β-甘露糖苷立体选择性形成中的反应性中间体所强调的那样。近来，已经清楚的是，类似S（N）1的反应途径也可以导致高度选择性的糖基化反应。这篇综述描述了立体选择性糖基化的一些最新实例，其中氧杂碳鎓离子被认为是选择性的基础。
• Mannopyranosyl Uronic Acid Donor Reactivity
  作者：Marthe T. C. Walvoort、Wilbert de Witte、Jesse van Dijk、Jasper Dinkelaar、Gerrit Lodder、Herman S. Overkleeft、Jeroen D. C. Codée、Gijsbert A. van der Marel

  DOI：10.1021/ol2016862

  日期：2011.8.19

  The reactivity of a variety of mannopyranosyl uronic acid donors was assessed In a set of competition experiments, in which two (S)-tolyl mannosyl donors were made to compete for a limited amount of promoter (NIS/TfOH). These experiments revealed that the reactivity of mannuronic acid donors is significantly higher than expected based on the electron-withdrawing capacity of the C-5 carboxylic acid ester function. A 4-O-acetyl-beta-(S)-tolyl mannuronic acid donor was found to have similar reactivity as per-O-benzyl-alpha-(S)-tolyl mannose.