催化分子内氧化的玛-和三角-氧烯形成循环
Hua Qian1, Xiaoqing Han, Ross A Widenhoefer
1P. M. Gross Chemical Laboratory, Duke University, Durham, North Carolina 27708-0346, USA.
Journal of the American Chemical Society
|August 5, 2004
概括
催化剂促进氧烯的氧化,有效合成替代的四基和四基衍生物. 这种方法展示了广泛的功能组耐受性和适用于复杂的化和螺旋环乙烯的适用性.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 合成方法论 合成方法论
背景情况:
- 油脂的氧化是有机合成中的一个关键转化.
- 开发高效的催化系统,用于循环形成是至关重要的.
- 催化为氨酸功能化提供了独特的反应性.
研究的目的:
- 为了研究催化氧化的马-氧烯.
- 探索这种催化反应的范围和局限性.
- 为了合成具有高产量的替代四二衍生物.
主要方法:
- 2,2-二-4-丁-1-醇与催化剂系统的反应 ([PtCl2(H2C=CH2) ]2和P(4-C6H4CF3) 3).
- 优化反应条件,包括温度和时间.
- 对产品产量的分析和合成的四水的表征.
主要成果:
- 在78%的产量中分离2-甲基-4,4-二四甲.
- 证明了催化氧化对烯酸和相邻碳的各种替代物的耐受性.
- 成功应用于化和螺旋环乙烯合成,并从三角氧烯中形成四基衍生物.
结论:
- 催化氧化是合成替代循环乙烯的通用方法.
- 该方法表现出广泛的功能组耐受性,使复杂分子合成成为可能.
- 这种方法提供了一个有效的途径,以有价值的异环化合物.
相关概念视频
03:00Preparation of Epoxides
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:22Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
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01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
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