基合成通过分子内化有机 ((I) 与 Ester 的合成
Tomoya Miura1, Taisuke Sasaki, Hiroki Nakazawa
1Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan.
Journal of the American Chemical Society
|February 3, 2005
概括
新的催化反应通过分子内化有效地形成循环. 这种方法在一个步骤中构建复杂的2-norbornanone骨架,使有价值的有机化合物的高效合成成为可能.
科学领域:
- 有机化学 有机化学
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
背景情况:
- 循环子是天然产品和药品中重要的结构动图.
- 构建循环基支架的高效和选择性方法在合成化学中非常受欢迎.
研究的目的:
- 开发用于合成循环的新型循环化反应.
- 通过涉及多个碳-碳键形成的单步过程构建2-norbornanone骨架.
主要方法:
- 开发新的循环化反应,利用有机 (I) 中间体.
- 通过有机 (I) 物种对一个基组的内分子化.
- 催化循环涉及产生一个氧 () 种.
主要成果:
- 成功开发新的循环化反应,形成循环子.
- 在单个合成操作中构建2-norbornanone骨架.
- 产生一种促进催化循环的氧 (alkoxyrhodium) 种.
结论:
- 开发的催化反应提供了一条有效的循环的途径.
- 该方法允许快速组装复杂的分子架构,如2-norbornanone骨架.
- 催化系统是强大的,并为随后的循环再生活跃物种.
相关概念视频
00:57Nitriles to Ketones: Grignard Reaction
Organomagnesium halides, commonly known as Grignard reagents, convert nitriles to ketones and proceed through a nucleophilic acyl substitution. Nitriles react with a Grignard reagent, followed by an aqueous acid, to yield ketones. The reaction introduces a new carbon–carbon bond. The alkyl–magnesium bond in the Grignard reagent is highly polar, so the alkyl carbon develops a carbanionic character and acts as a nucleophile.
The mechanism begins with a nucleophilic attack by the Grignard reagent...
The mechanism begins with a nucleophilic attack by the Grignard reagent...
01:13Intramolecular Claisen Condensation of Dicarboxylic Esters: Dieckmann Cyclization
Dieckmann cyclization is an intramolecular Claisen condensation of diesters. The reaction occurs in the presence of a base and generates a cyclic β-ketoester as the final product. Commonly, 1, 6 and 1, 7-diesters are preferred substrates for the reaction since the generated five, and six-membered cyclic β-keto esters are particularly more stable.
01:19α-Hydroxy Ketones via Reductive Coupling of Esters: Acyloin Condensation Overview
The pinacol and McMurry reactions involve the reductive coupling of ketones or aldehydes. Similarly, the bimolecular reductive coupling of two ester molecules in the presence of sodium metal in an aprotic solvent yields an α-hydroxy ketone product. The α-hydroxy ketone is also called acyloin, so the reaction is referred to as ‘acyloin condensation.’
01:07Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis
Acetoacetic ester synthesis is a method to obtain ketones from alkyl halides and β-keto esters. The reaction occurs in the presence of an alkoxide base that abstracts the acidic proton of the β-keto esters. The step results in an enolate ion which is doubly stabilized. The enolate then reacts with an alkyl halide via the SN2 process to produce an alkylated ester intermediate with a new C–C bond. The hydrolysis of the intermediate, followed by acidification, results in an alkylated β-keto acid.
01:14Alkylation of β-Diester Enolates: Malonic Ester Synthesis
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
01:27Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).