選択的C-H活性化アルファからプライマリアミンへ. ブリッジングメタラジリジンは,触媒的,分子内アルファ-アルキレーションのためのブリッジングメタラジリジンである
Jason A Bexrud1, Patrick Eisenberger, David C Leitch
1Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B.C, Canada, V6T 1Z1.
Journal of the American Chemical Society
|January 29, 2009
まとめ
研究者らは,ブリッジング金属アジリジン複合体を用いて,一次アミンのアルファ-アルキル化のための新しい触媒方法を開発しました. このアプローチは,窒素保護基を必要とせずに,効率的に四次性キラルセンターを作成します.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- 合成有機化学 合成有機化学について
背景:
- 選択的なC-H活性化は,効率的な合成に不可欠です.
- アミン機能化のための新しい触媒システムを開発することは,継続的な課題です.
- 窒素に隣接する四次性キラルセンターは,重要な構造モチーフです.
研究 の 目的:
- 主要アミンのアルファアルキル化のための新しい触媒方法の開発.
- 最初の橋渡し金属アジリジン複合体を合成し,特徴づけること.
- アルファから窒素までの四次性キラルセンターの形成を調査する.
主な方法:
- 選択的なα-C-H活性化反応.
- 新しいジルコニウム2-ピリドナート複合物の開発.
- 予備研究を用いたメカニズム調査.
主要な成果:
- 最初の橋渡し金属アジリジン複合体の合成が成功しました.
- 主要アミンの触媒性アルファアルキレーションは,窒素保護なしで達成される.
- アルファから窒素までの四次性キラルセンターの形成が実証された.
- ブリッジングメタルアジリジンの活性中間物質としての識別.
結論:
- 開発された方法は,一次アミンのアルファアルキル化のための新しい経路を提供します.
- ジルコニウム2-ピリドナート複合体は,この変換の効果的な触媒である.
- この反応により,複雑な分子構造の構築が可能になります.
関連する概念動画
01:30Preparation of Amines: Alkylation of Ammonia and Amines
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...
01:22Preparation of 1° Amines: Azide Synthesis
Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
01:28Preparation of 1° Amines: Gabriel Synthesis
Direct alkylation is not a suitable method for synthesizing amines because it produces polyalkylated products. Gabriel synthesis is the most preferred method to exclusively make primary amines. The method uses phthalimide, which contains a protected form of nitrogen that participates in alkylation only once to predominantly give primary amines.
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
01:10α-Alkylation of Ketones via Enolate Ions
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the strong interaction...