对N1999A2的酶选择性合成
Nan Ji1, Hardwin O'Dowd, Brad M Rosen
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Journal of the American Chemical Society
|November 16, 2006
概括
研究人员开发了一种21个步骤的选择性合成,用于enediyne抗生素N1999A2,首次实现了固体形式. 这一突破使得对这种复杂分子的进一步研究成为可能.
科学领域:
- 有机化学 有机化学
- 药用化学 医学化学
- 合成化学 合成化学
背景情况:
- 恩迪因抗生素N1999A2是一种复杂的天然产品,具有显著的治疗潜力.
- 以前的合成努力受到中间体的不稳定性和缺乏可扩展路线的阻碍.
- 开发一种高效和对抗选择性合成对于释放N1999A2.2.的全部潜力至关重要.
研究的目的:
- 建立一种新的,对恩迪因抗生素N1999A2.2.产生新的,对恩迪因抗生素的选择性合成途径.
- 为了克服与之前的合成试验中中期不稳定性和低产量相关的挑战.
- 为进一步的生物和药理学研究提供一种可靠的生产N1999A2的方法.
主要方法:
- 设计了一个21个步骤的融合合成,从 (R) -(+) -glycidol开始.
- 关键的转换包括催化合,分子内氧化循环和跨环状阴离子循环.
- 由于晚期中间体的不稳定性,必须仔细操纵保护组.
主要成果:
- 合成实现了0.4%的整体收益率,平均步骤收益率为77%.
- 三个关键片段的融合组合:一个 (1-乙烯) 斯坦,一个1,5-hexadiyne-3,4-diol衍生物,和一个替代的酸.
- 最后一步涉及三组同时剥离保护,以76%的产量产生合成N1999A2,并使其作为固体沉.
结论:
- 已经成功开发了一种强大且对N1999A2具有抗选择性的合成途径.
- 能够将N1999A2作为固体分离出来,这对其研究和潜在应用来说是一个重大进步.
- 这种合成为未来研究N1999A2.2.的生物活性和治疗应用提供了基础.
相关概念视频
Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon.
Nucleophilic Aromatic Substitution: Addition–Elimination (SNAr)
Nucleophilic substitution in aromatic compounds is feasible in substrates bearing strong electron-withdrawing substituents positioned ortho or para to the leaving group. The reaction proceeds via two steps: the addition of the nucleophile and the elimination of the leaving group.
The reaction begins with an attack of the nucleophile on the carbon that holds the leaving group. This results in the delocalization of the π electrons over the ring carbons. The resonance interaction between the...
The reaction begins with an attack of the nucleophile on the carbon that holds the leaving group. This results in the delocalization of the π electrons over the ring carbons. The resonance interaction between the...
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
Preparation 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...
2° Amines to N-Nitrosamines: Reaction with NaNO2
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
Preparation 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...


