Ethyl (E)-4-O-(tert-butyldiphenylsilyl)-2,3,6,7,8-pentadeoxy-α-D-erythro-nona-2,7-dienopyranoside

• 分子结构分类: 有机化合物 - 有机金属化合物 - 有机类金属化合物
• 英文名称: Ethyl (E)-4-O-(tert-butyldiphenylsilyl)-2,3,6,7,8-pentadeoxy-α-D-erythro-nona-2,7-dienopyranoside
• 英文别名: (E)-4-[(2R,3S,6S)-3-[tert-butyl(diphenyl)silyl]oxy-6-ethoxy-3,6-dihydro-2H-pyran-2-yl]but-2-en-1-ol
• 化学式: C₂₇H₃₆O₄Si
• 分子量: 452.666
• InChiKey: YRWVTYYNBXTYKT-VOFHUOPJSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  4.19
• 重原子数：
  32
• 可旋转键数：
  10
• 环数：
  3.0
• sp3杂化的碳原子比例：
  0.41
• 拓扑面积：
  47.9
• 氢给体数：
  1
• 氢受体数：
  4

反应信息

• 作为反应物：
  描述：

  二苯二硫醚 、 Ethyl (E)-4-O-(tert-butyldiphenylsilyl)-2,3,6,7,8-pentadeoxy-α-D-erythro-nona-2,7-dienopyranoside 在 吡啶 、 三丁基膦 作用下， 以94%的产率得到Ethyl (E)-4-O-(tert-butyldiphenylsilyl)-2,3,6,7,8,9-hexadeoxy-9-(phenylthio)-α-D-erythro-nona-2,7-dienopyranoside
  参考文献：
  名称：

  Serial Radical Cyclization of Pyranose-Derived Dienes in the Stereocontrolled Synthesis of Woodward's Reserpine Precursor

  摘要：

  A new strategy for the synthesis of Woodward's densely functionalized carbocyclic precursor to reserpine (2) that is based upon serial radical 5-exo/6-exo cyclizations of readily prepared dienic hexopyranose derivatives has been examined. The substrates 4, 7, 9, and 12, which are obtainable in simple steps from commercially available triacetylglucal, have their unsaturations on-template at C2 and off-template at C7, and the cyclization sequence is triggered by use of a silicon tether appendage placed at C-4 in the pyran ring. The first radical cyclization takes place onto the s Delta(2,3) unsaturation and serves the dual purpose of introducing a carbon branch at C-3 in a complete regio- and stereocontrolled manner as well as generating a radical at C-2 that experiences the 6-exo-trig ring closure to form the actual cyclohexane ring in which all but one of the required stereocenters have been established. Electron-withdrawing substituents that accelerate the 6-exo-trig ring closure, as in substrates 4(a and b), were found to be necessary for the second cyclization to take place in good yields. Nevertheless, some cyclohexane formation was also obtained in the radical cyclization of substrates 9(a and b) in which an allylic phenyl sulfide was used as the C-7 trap. The presence of an acetate substituent at C-6 in the latter cases resulted in a high degree of stereocontrol for the 6-exo cyclization process based in a stereochemical model that invokes release of 1,3 allylic strain in the transition state for the radical cyclization. The compounds resulting from the radical cyclizations of 4a,b and 9a,b were transformed to the same [2.2.2]oxabicyclic intermediate 34 that was correlated with Woodward's carbocyclic intermediate after opening of the glycosidic bond.

  DOI：

  10.1021/jo00117a043
• 作为产物：
  描述：

  ethyl (E)-uronate 在 二异丁基氢化铝 作用下， 以 正己烷 、 二氯甲烷 为溶剂， 以86%的产率得到Ethyl (E)-4-O-(tert-butyldiphenylsilyl)-2,3,6,7,8-pentadeoxy-α-D-erythro-nona-2,7-dienopyranoside
  参考文献：
  名称：

  Serial Radical Cyclization of Pyranose-Derived Dienes in the Stereocontrolled Synthesis of Woodward's Reserpine Precursor

  摘要：

  A new strategy for the synthesis of Woodward's densely functionalized carbocyclic precursor to reserpine (2) that is based upon serial radical 5-exo/6-exo cyclizations of readily prepared dienic hexopyranose derivatives has been examined. The substrates 4, 7, 9, and 12, which are obtainable in simple steps from commercially available triacetylglucal, have their unsaturations on-template at C2 and off-template at C7, and the cyclization sequence is triggered by use of a silicon tether appendage placed at C-4 in the pyran ring. The first radical cyclization takes place onto the s Delta(2,3) unsaturation and serves the dual purpose of introducing a carbon branch at C-3 in a complete regio- and stereocontrolled manner as well as generating a radical at C-2 that experiences the 6-exo-trig ring closure to form the actual cyclohexane ring in which all but one of the required stereocenters have been established. Electron-withdrawing substituents that accelerate the 6-exo-trig ring closure, as in substrates 4(a and b), were found to be necessary for the second cyclization to take place in good yields. Nevertheless, some cyclohexane formation was also obtained in the radical cyclization of substrates 9(a and b) in which an allylic phenyl sulfide was used as the C-7 trap. The presence of an acetate substituent at C-6 in the latter cases resulted in a high degree of stereocontrol for the 6-exo cyclization process based in a stereochemical model that invokes release of 1,3 allylic strain in the transition state for the radical cyclization. The compounds resulting from the radical cyclizations of 4a,b and 9a,b were transformed to the same [2.2.2]oxabicyclic intermediate 34 that was correlated with Woodward's carbocyclic intermediate after opening of the glycosidic bond.

  DOI：

  10.1021/jo00117a043

文献信息

• Serial Radical Cyclization of Pyranose-Derived Dienes in the Stereocontrolled Synthesis of Woodward's Reserpine Precursor
  作者：Ana M. Gomez、J. Cristobal Lopez、Bert Fraser-Reid

  DOI：10.1021/jo00117a043

  日期：1995.6

  A new strategy for the synthesis of Woodward's densely functionalized carbocyclic precursor to reserpine (2) that is based upon serial radical 5-exo/6-exo cyclizations of readily prepared dienic hexopyranose derivatives has been examined. The substrates 4, 7, 9, and 12, which are obtainable in simple steps from commercially available triacetylglucal, have their unsaturations on-template at C2 and off-template at C7, and the cyclization sequence is triggered by use of a silicon tether appendage placed at C-4 in the pyran ring. The first radical cyclization takes place onto the s Delta(2,3) unsaturation and serves the dual purpose of introducing a carbon branch at C-3 in a complete regio- and stereocontrolled manner as well as generating a radical at C-2 that experiences the 6-exo-trig ring closure to form the actual cyclohexane ring in which all but one of the required stereocenters have been established. Electron-withdrawing substituents that accelerate the 6-exo-trig ring closure, as in substrates 4(a and b), were found to be necessary for the second cyclization to take place in good yields. Nevertheless, some cyclohexane formation was also obtained in the radical cyclization of substrates 9(a and b) in which an allylic phenyl sulfide was used as the C-7 trap. The presence of an acetate substituent at C-6 in the latter cases resulted in a high degree of stereocontrol for the 6-exo cyclization process based in a stereochemical model that invokes release of 1,3 allylic strain in the transition state for the radical cyclization. The compounds resulting from the radical cyclizations of 4a,b and 9a,b were transformed to the same [2.2.2]oxabicyclic intermediate 34 that was correlated with Woodward's carbocyclic intermediate after opening of the glycosidic bond.