アレン酸エステルとアルファ,ベータ不飽和カルボニルとのアミン触媒結合
Catherine A Evans1, Scott J Miller
1Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467-3860, USA.
Journal of the American Chemical Society
|October 9, 2003
まとめ
核性アミンは,不飽和カルボニル化合物に1,4-アレン酸エステルを添加することを可能にします. この反応により,穏やかな条件下で複雑な分子の1つのポット,3つの成分合成が可能になります.
科学分野:
- 有機化学 オーガニック・ケミストリー
- カタリシス カタリシス カタリシス
背景:
- アルファ,ベータ不飽和カルボニル化合物は,汎用性の高い合成中間物質です.
- アレン酸エステルは,有機合成における貴重な構成要素である.
- 炭素-炭素結合形成のための効率的な触媒方法の開発は極めて重要です.
研究 の 目的:
- アレン酸エステルの1,4-添加における核性アミンの触媒活性を調べる.
- この反応における電気愛好体としてのベイリス・ヒルマン産物の使用を調査する.
- ワンポット・トライコンポーネント・カップリング戦略を策定する.
主な方法:
- 様々な核性アミンを用いた触媒反応スクリーニング.
- 反応条件 (温度,溶剤,濃度) の最適化.
- 基板の適用範囲と機能グループ耐性の調査.
主要な成果:
- 核性アミンは,アルファ,ベータ不飽和カルボニル化合物へのアレン酸エステルの1,4添加を効果的に触媒化する.
- 反応は穏やかな条件下で効率的に進行します.
- ベイリス・ヒルマン・アダクトは,電ophilesとして成功裏に採用され,1ポット,3コンポーネントのカップリングを可能にしました.
結論:
- 核性アミン触媒は,アレン酸エステルの結合添加のための効率的な経路を提供します.
- 開発されたワンポット・トライコンポーネント反応は,複雑な分子を合成するための簡素化されたアプローチを提供します.
- この方法論は,アレン酸エステルとベイリス・ヒルマン製品の合成有用性を拡大します.
さらに関連する動画
関連する概念動画
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Similar to water, alcohols can add to the carbonyl carbon of the aldehydes and ketones. The addition of one molecule of alcohol to the carbonyl compound forms the hemiacetal or half acetal. As depicted below, in a hemiacetal, the carbon is directly linked to an OH and OR group.
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
01:16Amines to Alkenes: Hofmann Elimination
Alkenes can be obtained from amines via an E2 elimination. The amine is first converted into a good leaving group, such as a quaternary ammonium salt. This is accomplished by treating the amine with an excess of alkyl halide, which results in a halide salt. Next, the halide salt is transformed into a hydroxide salt that functions as a base to enable elimination.
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
01:15Acid-Catalyzed Aldol Addition Reaction
The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The acid-catalyzed aldol reaction is depicted in Figure 1.
01:27Aldol Condensation with β-Diesters: Knoevenagel Condensation
The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as β-diesters to produce substituted olefins.
01:07Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis
Acetoacetic ester synthesis is a method to obtain ketones from alkyl halides and β-keto esters. The reaction occurs in the presence of an alkoxide base that abstracts the acidic proton of the β-keto esters. The step results in an enolate ion which is doubly stabilized. The enolate then reacts with an alkyl halide via the SN2 process to produce an alkylated ester intermediate with a new C–C bond. The hydrolysis of the intermediate, followed by acidification, results in an alkylated β-keto acid.