使用动态分辨率策略的初级氨基的纳米分子尺度配置分配
Shawn M Miller1, Renzo A Samame, Scott D Rychnovsky
1Department of Chemistry, 1102 Natural Sciences II, University of California-Irvine, Irvine, California 92697, United States.
Journal of the American Chemical Society
|December 6, 2012
概括
现在确定初级氨基的立体化学方法变得更加简单了. 一种新的动力分辨率方法使用选性化剂和质谱学来准确地分配配置,即使是小样本.
科学领域:
- 有机化学 有机化学
- 分析化学 分析化学
- 立体化学是一种立体化学.
背景情况:
- 在化学中,赋予像初级氨基酸这样的性分子绝对配置至关重要.
- 现有的确定氨酸立体化学的方法可能很复杂或需要大量的样本.
研究的目的:
- 开发一种简单而灵敏的方法来分配初级氨基的绝对配置.
- 使用新型选性乙化剂的动力分辨率策略.
主要方法:
- 采用米奥斯科夫斯基的酶选择性1 - ((R,R) 和2 - ((S,S) 乙化剂,用于初级氨基的动力分离.
- 开发了一个简单的记忆器来帮助确定分配的配置.
- 使用伪反体对试剂 (1-(R,R) 和2-(S,S) -d(3)) 在微分子尺度上测定氨基.
- 使用电子喷雾离子质谱法 (ESI-MS) 分析了得到的乙胺产品.
主要成果:
- 乙胺产品的ESI-MS分析准确地反映了通过动力实验确定的选择性因子.
- 该方法在分配配置时显示出高的enantioselectivity.
- 开发的策略成功地确定了胺基混合物的配置.
- 这种方法在50纳米分子的氨基样本上得到了验证.
结论:
- 已经建立了一种新,高效和敏感的方法来分配初级氨基的绝对配置.
- 动力分辨率,记忆器和ESI-MS的组合为立体化学分析提供了强大的工具.
- 这种方法适用于复杂的混合物,并且需要最小的样本量,从而推进了奇拉胺氨基分析.
相关概念视频
Structure of Amines
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...
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The secondary and tertiary amines are derivatives of ammonia, where two and three of its hydrogens are replaced by alkyl groups, respectively. Secondary and tertiary amines can be symmetrical with identical alkyl groups attached to the nitrogen atom or unsymmetrical when more than one type of alkyl group is present. The standard nomenclature of secondary and tertiary amines is similar to the names given to the primary amines. They are generally named alkylamines. As depicted in Figure 1, for...
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Carbonyl compounds and primary amines undergo reductive amination first to produce imines, followed by secondary amines in the same reaction mixture, using selective reducing agents like sodium cyanoborohydride or sodium triacetoxyborohydride. Reductive amination produces different degrees of substitution of amines depending on the starting amine substrate.
Mass Spectrometry of Amines
In mass spectroscopy, amines undergo fragmentation to give parent ions with odd molecule weights. This observed mass spectrum follows the nitrogen rule; a molecule with an odd number of nitrogen atoms produces a molecular ion with an odd molecular weight. Amines undergo fragmentation through α cleavage, producing nitrogen-containing cations—iminium ions—and alkyl radicals. Mass spectra of aromatic and cyclic aliphatic amines exhibit strong molecular ion peaks, but acyclic aliphatic amines show...
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Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
NMR Spectroscopy Of Amines
In proton NMR spectroscopy, primary amines and secondary amines showcase their N–H protons as a broad signal in the chemical shift range between δ 0.5 and 5 ppm. The exact position in this range depends on several factors, including sample concentration, hydrogen bonding, and the type of solvent used. Since amine protons undergo fast proton exchange in solution, the protons are labile and therefore do not participate in any splitting with adjacent protons. Thus, the observed peak is broad and...


