相关实验视频
Updated: Jul 17, 2026

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Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
合成 (-) - 四环素的合成
Mark G Charest1, Dionicio R Siegel, Andrew G Myers
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Journal of the American Chemical Society
|June 9, 2005
概括
这项研究详细介绍了从酸中合成 (-) - 四环素的17个步骤的酶选择合成,实现了1.1%的总产量. 关键步骤包括Diels-Alder循环添加和立体选择性氧化,以有效生产抗生素.
科学领域:
- 有机化学 有机化学
- 合成化学 合成化学
- 药用化学 医学化学
背景情况:
- 四环素抗生素对于治疗细菌感染至关重要.
- 为四环素等复杂的天然产品开发高效的合成路径对于药物发现和开发至关重要.
- 之前的合成在立体选择性和整体产量方面面临着挑战.
研究的目的:
- 为了建立 (-) - 四环素的融合和enantioselective合成.
- 优化关键步骤,包括Diels-Alder循环添加和氧化,以提高效率.
- 为进一步研究提供一种可靠的 (-) - 四环素生产方法.
主要方法:
- 一个从酸开始的17步合成.
- 通过引入alpha-phenylthio组来激活一个AB前体,用于Diels-Alder循环添加.
- 立体选择性氧化和随后的转化,包括自氧化和解.
- 使用了关键中间体,如α-甲和子基衍生物.
主要成果:
- 从酸中获得了 (-) - 四环素的融合性,对抗选择性合成,总产量为1.1%.
- 迪尔斯-阿尔德循环添加产生了64%的内附产物.
- 最后的解步骤产生 (-) - 四环素在42%的收益率从中间的7.
- 合成的 (-) - 四环素与真实样本无法区分.
结论:
- 已经开发出一种可行且对 (-) - 四环素有选择性的合成途径.
- 描述的方法为构建复杂的四环素结构提供了一种战略方法.
- 这种合成为潜在的大规模生产和模拟开发提供了基础.
相关概念视频
Synthesis and Decomposition Reactions
Synthesis and decomposition are two types of redox reactions. Synthesis means to make something, whereas decomposition means to break something. The reactions are accompanied by chemical and energy changes.
Cycloaddition Reactions: Overview
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
Radical Formation: Addition
Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an unpaired...
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Radical Formation: Elimination
Another method of radical formation is the elimination process. It is the opposite of the addition route and is driven by the instability of the radical. For example, as depicted in Figure 1, dibenzoyl peroxide yields a pair of unstable radicals upon homolysis. Given its instability, this radical spontaneously undergoes elimination via a C–C bond cleavage to form a relatively more stable phenyl radical. The mechanism involves cleavage of the bond between the α and β positions with respect to...
Conjugate 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...

