1,3-或阿里基因的内分子 [4 + 2] 循环添加与具有高度反应性的阴离子素 Au (I) 复合物的基因
Cristina Nieto-Oberhuber1, Salomé López, Antonio M Echavarren
1Institute of Chemical Research of Catalonia (ICIQ), 43007 Tarragona, Spain.
Journal of the American Chemical Society
|April 28, 2005
概括
新黄金(I) 具有庞大的素的催化剂有效地催化其他循环. 这些反应通过特定的循环化途径产生复杂的多环结构,如四[b]和.
科学领域:
- 有机金属化学 有机金属化学
- 有机合成 有机合成
- 催化剂是一种催化剂.
背景情况:
- 恩尼循环是构建复杂分子架构的多功能反应.
- 开发高效和选择性催化剂对于推进合成方法至关重要.
研究的目的:
- 探索新型黄金的催化活性 (I) 复合物与体积大的双酸在 enyne 循环中.
- 为了研究不同的enyne基质的反应途径和产品选择性.
主要方法:
- 合成新的黄金 (I) 复合物,其中包括重的双酸联体.
- 这些复合物的催化测试在各种内循环反应中.
- 使用光谱技术阐明所得到的循环产品的结构.
主要成果:
- 新型黄金 (I) 复合物表现出高反应性和效率,作为其他循环的催化剂.
- 在基因上携带基团的1,6-Enynes经历了5-exo-dig循环化,随后进行了Nazarov型环扩张,产生2,3,9,9a-tetrahydro-1H-cyclopenta[b]naphthalenes.
- 1,8-丁-3-通过一个5exo-dig路径循环,提供二衍生物.
结论:
- 大量的双烯酸支持的金 (((I) 复合物代表了对enyne循环的高度有效的催化剂.
- 开发的催化系统为合成有价值的多环化合物提供了强大的途径.
相关概念视频
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
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.
01:14Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Electrophilic addition of halogens to alkenes proceeds via a cyclic halonium ion to form a 1,2-dihalide or a vicinal dihalide.
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.