新的双联催化:通过催化环闭转化-烯异体化序列制备循环乙醇
Amanda E Sutton1, Benjamin A Seigal, David F Finnegan
1Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
Journal of the American Chemical Society
|November 7, 2002
概括
这项研究引入了一种结合环闭转化和氨酸异构的新联体反应. 这种高效的过程使用单个催化剂从非循环二烯中产生循环乙醇.
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:
- 协奏反应在合成化学中提供了更高的效率.
- 使用单金属催化剂开发新的反应序列是关键目标.
- 催化剂被广泛用于olefin转化.
研究的目的:
- 开发一种用于合成循环乙醇乙的双重反应序列.
- 为了确定一个结合环闭转化和烯异构化过程的反应条件.
- 在两个催化步骤中使用一种常见的前体.
主要方法:
- 使用格拉布斯的鲁基基催化剂.
- 调查协同催化反应的反应条件.
- 使用易于获得的非循环二烯作为起始材料.
主要成果:
- 成功实现了双环闭合转化-烯异体化序列.
- 从各种非循环二烯中生成循环乙醇.
- 证明了单个鲁前体在合工艺中的有效性.
结论:
- 开发的双重反应提供了一个有效的循环乙醇乙烯的途径.
- 这种方法简化了合成途径,将两个反应结合在一个中.
- 单个催化剂前体的使用凸显了它在复杂转换中的多功能性.
相关概念视频
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
01:16Cycloaddition 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.
01:28Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
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01:24[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
The Claisen rearrangement is a [3,3] sigmatropic rearrangement of allyl vinyl ethers to unsaturated carbonyl compounds. The rearrangement is a concerted pericyclic reaction proceeding via a chair-like transition state.