立体选择性易斯酸催化阿尔法-乙乙烯添加剂
Troy E Reynolds1, Ashwin R Bharadwaj, Karl A Scheidt
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
Journal of the American Chemical Society
|November 30, 2006
概括
这项研究引入了一种新的方法,用于从propargylsilanes中合成silicloxyallenes,从而使化物能够有效地进行不对称的添加. 该过程保留了光学活性,为新的性化合物产生了高的enantioselectivity.
科学领域:
- 有机化学 有机化学
- 不对称的合成方法
- 有机化学 有机化学
背景情况:
- 阿尔法-基基基烯酸是多功能合成前体.
- 锡基烯是有机合成中的反应性中间体.
- 催化不对称的反应对于产生反分子纯化合物至关重要.
研究的目的:
- 开发一种高效的合成力基烯的方法.
- 为了研究化物对化物的催化不对称的silylloxyallenes的添加.
- 为了建立一个路径,对有价值的性分子的enantioselective合成.
主要方法:
- 基因催化1,2-布鲁克对propargylsilanes进行重新排列,以获得sylloxyallenes.
- 促进的添加到acylsilanes的alkynes,用于丰富的propargylsilane合成.
- 催化不对称的添加使用一种性(III) 易斯酸.
主要成果:
- 锡基烯从α-hydroxypropargylsilanes中得到了有效的合成.
- 以高达74% ee.e.的基基基基基基基基基基基基基基基基基基基基基
- 催化不对称的添加 Racemic 锡基烯 化物 产生的产品高达 92% ee.
- 转换成西基烯显示光学活动的损失最小.
结论:
- 已经开发出一种新且高效的合成路径,用于制造西洛克赛.
- 该方法允许催化不对称合成具有高enantioselectivity的奇拉化合物.
- 该反应具有广泛的基质范围,使其适用于各种芳香和酸化合物.
相关概念视频
02:42Acidity of 1-Alkynes
The acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.
00:53Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
01:15Acid-Catalyzed Aldol Addition Reaction
The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The acid-catalyzed aldol reaction is depicted in Figure 1.