具有高度选择性的催化剂依赖的竞争性1,2-C→C, -O→C,和 -N→C从β-甲-β-silyloxy-β-amido-α-diazoacetates的迁移
Xichen Xu1, Yu Qian, Peter Y Zavalij
1Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
Journal of the American Chemical Society
|January 16, 2013
概括
过渡金属催化剂使复杂的有机分子中碳,氧和的选择性迁移成为可能. 这种控制是通过金属碳在催化过程中具有独特的固体和立体电子特性来实现的.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 有机金属化学 有机金属化学
背景情况:
- 酸是一种多功能合成中间体.
- 过渡金属催化对于选择性键形成至关重要.
- 控制复杂分子中的迁移途径仍然是一个挑战.
研究的目的:
- 研究过渡金属在指导迁移中的催化活性.
- 探索选择性的C→C,O→C和N→C键形成.
- 了解金属碳在控制反应通路中的作用.
主要方法:
- 使用过渡金属催化剂.
- 使用β-甲基-β-基-β-胺-α-酸作为基质.
- 分析反应产品的选择性和产量.
主要成果:
- 在1,2-C→C,O→C和N→C迁移中实现了高选择性.
- 证明了催化剂在迁移路径之间区分的能力.
- 识别了金属碳的固体和立体电子效应作为关键控制因素.
结论:
- 过渡金属催化剂可以精确控制迁移反应.
- 金属碳中间体在指导选择性方面发挥着至关重要的作用.
- 这种方法为合成复杂的有机结构提供了一个强大的工具.
相关概念视频
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Carboxylic acids react with diazomethane in an ether solvent via alkylation at the carboxylate oxygen atom to give methyl esters of the corresponding acid with excellent yields.
α-Alkylation of Ketones via Enolate Ions
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the strong interaction...
Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
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...


