(+) - シアンチウイギンUの総合合成
Matthew W B Pfeiffer1, Andrew J Phillips
1Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA.
Journal of the American Chemical Society
|April 14, 2005
まとめ
研究者は,新しい双方向のタンデムメタテシス反応を用いて,三環性テルペンのシアンチウィギンUの簡潔な全合成を達成しました. この効率的な方法は,わずか12のステップで複雑なサイクロヘプタ[e]インデンのコアを構築します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 自然製品合成 自然製品合成
- テルペノイドの化学的性質について
背景:
- シアンチウィギンUは,潜在的生物学的な重要性を持つ複雑な三循環型テルペンです.
- 以前,シアンチウィギンUへの合成経路は長く,効率が悪かった.
- 簡潔で高収益性の合成戦略の開発は,複雑な天然製品にアクセスするために不可欠です.
研究 の 目的:
- シアンチウイギンUの簡潔な総合成を達成するために.
- サイクロヘプタ[e]インデンの核を構成するための新しい合成方法論を確立する.
- 自然産物合成における双方向タンデムメタテシスの有用性を実証する.
主な方法:
- 12段階の合成シーケンスが設計され,実行されました.
- 重要な双方向のタンデムメタテシス反応が採用されました.
- 合成は,容易に入手可能なビサイクロ[2.2.2]オクテンの前駆体から始まった.
主要な成果:
- シアンチウィギンUの全合成が成功しました.
- 全体で17%の収益率を達成しました.
- サイクロヘプタ[e]インデンの核は,タンデムメタテシスによって効率的に構築されました.
結論:
- 簡潔で効率的なシアンチウィギンUの全合成が開発されました.
- 2方向のタンデムメタテシス反応は,複雑な多循環系を構成する強力なツールです.
- この合成は,シアンチウイギンUおよび関連する天然製品への貴重な経路を提供します.
関連する概念動画
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As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy carbonyl compound.
01:09Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.
01:27Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)
α,β-Unsaturated carbonyl compounds with two electrophilic sites, the carbonyl carbon, and the β carbon, are susceptible to nucleophilic attack via two modes: conjugate or 1,4-addition and direct or 1,2-addition.
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
01:09EDTA: Conditional Formation Constant
Each EDTA molecule has six binding sites: four carboxyl groups and two amino groups. The fully protonated form of EDTA is represented as H6Y2+. However, it can exist in different forms, H5Y+, H4Y, H3Y−, H2Y2−, and HY3−, depending on the pH of the solution. In very basic solutions with pH > 10.17, the fully deprotonated form, Y4−, is the predominant species that readily complexes with metal ions in a 1:1 ratio.
For the equilibrium reaction of the metal with the Y4− form of EDTA, the formation...
For the equilibrium reaction of the metal with the Y4− form of EDTA, the formation...
01:26EDTA: Auxiliary Complexing Reagents
EDTA titrations are usually carried out in highly basic conditions, where the fully deprotonated form of EDTA, Y4−, actively complexes with the free metal ions in the solution. Several metal ions precipitate as hydrous oxide (hydroxides, oxides, or oxyhydroxides) under these conditions, lowering the concentration of free metal ions in the solution. For this reason, auxiliary complexing agents or ligands such as ammonia, tartrate, citrate, or triethanolamine are used in EDTA titrations to...
01:16Combining Functions
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