(S)-N-(3-bromopropyl)-N-(tert-butoxycarbonyl)valine ethyl ester | 619307-04-9

• 分子结构分类: 有机化合物 - 有机酸及其衍生物 - 羧酸及其衍生物
• 英文名称: (S)-N-(3-bromopropyl)-N-(tert-butoxycarbonyl)valine ethyl ester
• 英文别名: ethyl (2S)-2-[3-bromopropyl-[(2-methylpropan-2-yl)oxycarbonyl]amino]-3-methylbutanoate
• CAS: 619307-04-9
• 化学式: C₁₅H₂₈BrNO₄
• 分子量: 366.296
• InChiKey: ILSMLTRCZCGPNI-LBPRGKRZSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  3.9
• 重原子数：
  21
• 可旋转键数：
  10
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.87
• 拓扑面积：
  55.8
• 氢给体数：
  0
• 氢受体数：
  4

反应信息

• 作为反应物：
  描述：

  (S)-N-(3-bromopropyl)-N-(tert-butoxycarbonyl)valine ethyl ester 在 氢氧化钾 作用下， 以 二甲基亚砜 为溶剂， 反应 2.0h， 以94%的产率得到N-(tert-butoxycarbonyl)-α-isopropylproline ethyl ester
  参考文献：
  名称：

  Powdered KOH in DMSO:  An Efficient Base for Asymmetric Cyclization via Memory of Chirality at Ambient Temperature

  摘要：

  Enolate chemistry has been extensively used for stereoselective C-C bond formation, in which metal amide bases are frequently employed in strictly anhydrous solvents at low temperatures. However, we found that asymmetric intramolecular C-C bond formation via axially chiral enolate intermediates proceeded in up to 99% ee at 20 degrees C using powdered KOH in dry or wet DMSO as a base. The enantioselectivity was even higher than that of the corresponding reactions with potassium hexamethyldisilazide in DIVIF at -60 degrees C. The racemization barrier of the axially chiral enolate intermediate was estimated to be similar to 15.5 kcal/mol. On the basis of the barrier, the chiral enolate intermediate was supposed to undergo cyclization within similar to 10(-3) sec at 20 degrees C after it is generated to give the product in 2 >= 99% ee. Thus, enolates generated with powdered KOH in DMSO were expected to be extremely reactive.

  DOI：

  10.1021/ja077684w

文献信息

• Asymmetric Cyclization via Memory of Chirality:  A Concise Access to Cyclic Amino Acids with a Quaternary Stereocenter
  作者：Takeo Kawabata、Shimpei Kawakami、Swapan Majumdar

  DOI：10.1021/ja0378299

  日期：2003.10.1

  N-(omega-Bromoalkyl)-amino acid derivatives, readily prepared from natural alpha-amino acids, gave cyclic amino acids with a quaternary stereocenter by treatment with potassium hexamethyldisilazaide in DMF. The chirality of parent amino acids was almost completely preserved during an enolate-formation and cyclization process, giving aza-cyclic amino acids in up to 98% ee in retention of configuration

  N-(ω-溴烷基)-氨基酸衍生物，很容易从天然α-氨基酸制备，通过在DMF中用六甲基二硅氮杂钾处理得到具有季立体中心的环状氨基酸。在烯醇化物形成和环化过程中，亲本氨基酸的手性几乎完全保留，使氮杂环氨基酸的构型保留率高达 98% ee。该方法适用于氮杂环丁烷、吡咯烷、哌啶和氮杂环庚烷衍生物的不对称合成。不对称环化似乎是通过轴向手性烯醇中间体而不是通过协调一致的 SEi 过程进行的。