非機能化,アルファエピメリゼーション可能な非血性ケトンとアルデヒドは,イミンの結晶化誘発のダイナミック解像によって得ることができる
Janez Kosmrlj1, Leland O Weigel, David A Evans
1Chemical Process R&D, Lilly Research Laboratories, Indianapolis, IN 46285-4813, USA. janez.kosmrlj@uni-lj.si
Journal of the American Chemical Society
|March 13, 2003
まとめ
この研究では,単純な結晶化誘発ダイナミック解像度 (CIDR) 方法を導入し,ラセミアルデヒドとケトンを効率的に単一のエナチオマーに変換します. このプロセスは,高収量とエナティオメール過剰を達成し,キラル化合物の合成のための実用的なアプローチを提供します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- アシンメトリック・シンセシス
- クリスタル化・結晶化
背景:
- キラル化合物の脱セミゼーションは,エナティオメリックに純粋な物質を合成するために不可欠です.
- 既存の方法は複雑で,広範囲の基板の適用には効率が欠けることがあります.
研究 の 目的:
- アルデヒドとケトンの操作的にシンプルで高度に効率的な脱酸化プロトコルの開発.
- 新型結晶化誘発ダイナミック解像度 (CIDR) プロセスのメカニズムと範囲を調査する.
主な方法:
- ラセミアルデヒド/ケトンとキラルアミン補助体 (トランス-1R,2R) - 1アミノ-6-ニトロインダン-2-オール) からイミンの形成.
- イミン誘導体のダイアステロセレクティブ結晶化.
- キラル補助物質を回収し,エナチオメリックに濃縮された製品を得るための二相水解.
主要な成果:
- ラセミ混合物のほぼ完全な変換を単一のエナティオマーに達成しました.
- 2メチルサイクロヘクサノン (97%/92% ee) と2エチルヘクサナル (94%/98% ee) を含む様々な基板について,高収量とエナティオメール過量 (ee) が観察されました.
- このプロセスは,さまざまなケトンとアルデヒドに対して有効性を示しました.
結論:
- 開発されたCIDRプロトコルは,脱血化のための強力で実用的な方法です.
- この高い効率は,イミンとキラル補助体の間の固体状態の相互作用 (pi-stackingと水素結合) に起因する.
- このプロセスは,キラル合成における工業的な応用の可能性を秘めています.
関連する概念動画
Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.
Acid Halides to Amides: Aminolysis
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
Preparation of Amines: Reductive Amination of Aldehydes and Ketones
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.
Aldehydes and Ketones with Amines: Imine Formation Mechanism
Imine formation involves the addition of carbonyl compounds to a primary amine. It begins with the generation of carbinolamine through a series of steps involving an initial nucleophilic attack and then several proton transfer reactions. The second part includes the elimination of water, as a leaving group, to give the imine.
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
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...
Determination of Crystal Structures
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...


