(±)-(2R,3R)-methyl 5-(benzyloxy)-3-hydroxy-2-methylpentanoate

• 分子结构分类: 有机化合物 - 苯类化合物 - 苯和取代衍生物
• 英文名称: (±)-(2R,3R)-methyl 5-(benzyloxy)-3-hydroxy-2-methylpentanoate
• 英文别名: methyl (2S,3S)-3-hydroxy-2-methyl-5-phenylmethoxypentanoate
• 化学式: C₁₄H₂₀O₄
• 分子量: 252.31
• InChiKey: IOYDJCCOTMVJHB-AAEUAGOBSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  1.7
• 重原子数：
  18
• 可旋转键数：
  8
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.5
• 拓扑面积：
  55.8
• 氢给体数：
  1
• 氢受体数：
  4

反应信息

• 作为反应物：
  描述：

  (±)-(2R,3R)-methyl 5-(benzyloxy)-3-hydroxy-2-methylpentanoate 在 palladium on activated charcoal 咪唑 、 4-二甲氨基吡啶 、 正丁基锂 、 N-甲基吲哚酮 、 四丙基高钌酸铵 、 amberlyst-15 、 四丁基氟化铵 、 水 、 氢气 、 二异丁基氢化铝 、 O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate 、 溶剂黄146 、 1,8-二氮杂双环[5.4.0]十一碳-7-烯 、 N,N-二异丙基乙胺 、 三氟乙酸 、 lithium chloride 作用下， 以 四氢呋喃 、 正己烷 、 二氯甲烷 、 N,N-二甲基甲酰胺 、 乙腈 为溶剂， -78.0~20.0 ℃ 、344.75 kPa 条件下， 反应 112.5h， 生成 desepoxyarenastatin A
  参考文献：
  名称：

  Total Synthesis of Cryptophycin-24 (Arenastatin A) Amenable to Structural Modifications in the C16 Side Chain

  摘要：

  Two efficient protocols for the synthesis of tert-butyl (5S,6R,2E,7E)-5-[(tert-butyldimethylsily oxy]-6-methyl-8-phenyl-2,7-octadienoate, a major component of the cryptophycins, are reported. The first utilized the Noyori reduction and Frater alkylation of methyl 5-benzyloxy-3-oxopentanoate to set two stereogenic centers, which became the C16 hydroxyl and C1' methyl oft-he cryptophycins. The second approach started from 3-p-methoxybenzyloxypropanal and a crotyl borane reagent derived from (-)-alpha -pinene to set both stereocenters in a single step and provided the dephenyl analogue, tert-butyl(5S,6R,2E)-5-[(tert-butyldimethylsilyl)oxy]-6 -methyl-2,7 -octadienoate, in five steps. This compound was readily converted to the 8-phenyl compound via Heck coupling. The silanyloxy esters were efficiently deprotected and coupled to the C2-C10 amino acid fragment to provide desepoxyarenastatin A and its dephenyl analogue. The terminal olefin of the latter was further elaborated via Heck coupling. Epoxidation provided cryptophycin-24 (arenastatin A).

  DOI：

  10.1021/jo000767+
• 作为产物：
  描述：

  3-苄氧基丙醛 在 Cp2Zr(OTf)2 、 溶剂黄146 作用下， 以 四氢呋喃 、 水 为溶剂， 反应 5.0h， 生成 (±)-(2R,3R)-methyl 5-(benzyloxy)-3-hydroxy-2-methylpentanoate
  参考文献：
  名称：

  Mukaiyama Aldol Reactions Catalyzed by Zirconocene Bis(triflate) Complexes:  Stereochemistry and Mechanisms for C−C Bond Formation

  摘要：

  The aldol condensations of alpha- and beta-(benzyloxy) aldehydes with enol silanes, catalyzed by Cp2Zr(OTf)(2) . THF or Cp2Zr(OTf)(2), in a variety of solvents were studied. The simple diastereoselectivity of these reactions is modest and comparable to that observed using simple aldehydes of similar steric requirements. Studies have revealed that TMSOTf is directly produced on reaction with the zirconocene catalyst with the enol silane in nitroalkane solvent or is formed during catalysis in dichloromethane solution. Although TMSOTf is known to catalyze cross-aldol reactions under these conditions, the rate of this process is not always competitive with that observed using the zircanocene catalysts. In particular, sterically unhindered or aromatic aldehydes react via a mechanism that appears to be mainly Zr-catalyzed, based on both the difference in rate between Zr- and Si-mediated reactions as well as differences in enol silane/silyl triflate reactivity in crossover-type experiments. With sterically hindered aldehydes in dichloromethane or nitromethane, catalysis is mediated by Si. The Zr-catalyzed process occurs via formation of a Zr-aldolate complex from aldehyde and enol silane, with liberation of TMSOTf, followed by rate-limiting O-silylatian of the metal aldolate by TMSOTf, as revealed by both model studies and in situ monitoring during catalysis.

  DOI：

  10.1021/jo971803g

文献信息

• Diastereoselective Hydrogen-Transfer Reactions: An Experimental and DFT Study
  作者：François Godin、Michel Prévost、Serge I. Gorelsky、Philippe Mochirian、Maud Nguyen、Frédérick Viens、Yvan Guindon

  DOI：10.1002/chem.201300377

  日期：2013.7.8

  an equatorial orientation. Hydride deliveries to different acyclic substrates and calculations also suggest that the higher anti‐selectivities obtained with borinate intermediates are not related to the formation of a complex mimicking an exocycle. From a broader standpoint, this study reveals important conformational factors for reactions taking place at a center vicinal to a heterocycle or an α‐alkoxy

  将带有杂环exo（α）的卤代前体自由基还原为以碳为中心的自由基，会增强抗选择性，这种现象我们称为“环外效应”。在BHandHLYP / TZVP级别的新实验数据和DFT计算表明，环外效应的起源与自由基中间体在过渡态（ΔE ≠应变）达到其反应构象所需的应变能有关。此外，受约束的THP系统的自由基减少表明，较高的2,3-抗只有当自由基链处于赤道取向时，才能达到诱导作用。氢化物可递送至不同的非环状底物，并且计算结果还表明，硼酸盐中间体可获得更高的抗选择性，与模拟环外化合物的复合物的形成无关。从更广泛的角度来看，这项研究揭示了重要的构象因子，这些构象是在中心邻位发生的对杂环或α-烷氧基的反应。
• Formal syntheses of cryptophycin A and arenastatin A
  作者：Syed M. Ali、Gunda I. Georg

  DOI：10.1016/s0040-4039(97)00194-9

  日期：1997.3

  Efficient formal syntheses of the tubulin binding antitumor agents cryptophycin A (1) and arenastatin A (2) are detailed. The readily available beta-keto ester 4 was subjected to catalytic asymmetric hydrogenation, Frater alkylation, and selective functional group transformations to provide the silyl ether of octanoic acid methyl ester 3, which is the key intermediate for the formal syntheses of the title compounds. (C) 1997 Elsevier Science Ltd.
• Total Synthesis of Cryptophycin-24 (Arenastatin A) Amenable to Structural Modifications in the C16 Side Chain
  作者：MariJean Eggen、Craig J. Mossman、Suzanne B. Buck、Sajiv K. Nair、Laxminarayan Bhat、Syed M. Ali、Emily A. Reiff、Thomas C. Boge、Gunda I. Georg

  DOI：10.1021/jo000767+

  日期：2000.11.1

  Two efficient protocols for the synthesis of tert-butyl (5S,6R,2E,7E)-5-[(tert-butyldimethylsily oxy]-6-methyl-8-phenyl-2,7-octadienoate, a major component of the cryptophycins, are reported. The first utilized the Noyori reduction and Frater alkylation of methyl 5-benzyloxy-3-oxopentanoate to set two stereogenic centers, which became the C16 hydroxyl and C1' methyl oft-he cryptophycins. The second approach started from 3-p-methoxybenzyloxypropanal and a crotyl borane reagent derived from (-)-alpha -pinene to set both stereocenters in a single step and provided the dephenyl analogue, tert-butyl(5S,6R,2E)-5-[(tert-butyldimethylsilyl)oxy]-6 -methyl-2,7 -octadienoate, in five steps. This compound was readily converted to the 8-phenyl compound via Heck coupling. The silanyloxy esters were efficiently deprotected and coupled to the C2-C10 amino acid fragment to provide desepoxyarenastatin A and its dephenyl analogue. The terminal olefin of the latter was further elaborated via Heck coupling. Epoxidation provided cryptophycin-24 (arenastatin A).
• Mukaiyama Aldol Reactions Catalyzed by Zirconocene Bis(triflate) Complexes:  Stereochemistry and Mechanisms for C−C Bond Formation
  作者：Shuqiong Lin、Georgiy V. Bondar、Christopher J. Levy、Scott Collins

  DOI：10.1021/jo971803g

  日期：1998.3.1

  The aldol condensations of alpha- and beta-(benzyloxy) aldehydes with enol silanes, catalyzed by Cp2Zr(OTf)(2) . THF or Cp2Zr(OTf)(2), in a variety of solvents were studied. The simple diastereoselectivity of these reactions is modest and comparable to that observed using simple aldehydes of similar steric requirements. Studies have revealed that TMSOTf is directly produced on reaction with the zirconocene catalyst with the enol silane in nitroalkane solvent or is formed during catalysis in dichloromethane solution. Although TMSOTf is known to catalyze cross-aldol reactions under these conditions, the rate of this process is not always competitive with that observed using the zircanocene catalysts. In particular, sterically unhindered or aromatic aldehydes react via a mechanism that appears to be mainly Zr-catalyzed, based on both the difference in rate between Zr- and Si-mediated reactions as well as differences in enol silane/silyl triflate reactivity in crossover-type experiments. With sterically hindered aldehydes in dichloromethane or nitromethane, catalysis is mediated by Si. The Zr-catalyzed process occurs via formation of a Zr-aldolate complex from aldehyde and enol silane, with liberation of TMSOTf, followed by rate-limiting O-silylatian of the metal aldolate by TMSOTf, as revealed by both model studies and in situ monitoring during catalysis.