Reactions between acyclic (E)-allylic acetates and arylboronic acids in the presence of a palladium catalyst prepared from Pd(OAc)(2), phenanthroline (or bipyridine), and AgSbF(6) (1:1.2:1) proceeded with excellent gamma-selectivity to afford allyl-aryl coupling products with E-configuration. The reactions of alpha-chiral allylic acetates took place with excellent alpha-to-gamma chirality transfer
hydroperoxidation. Within NaY, the diastereoselectivity may significantly depend on the site selectivity, as probed through specific deuterium labelling of trisubstituted alkenes bearing a gem-dimethyl group. In certain cases, a remote stereogenic centre relative to the reacting doublebond may induceenhanced diastereoselection and regioselectivity.
Stabilized carbanions by alkyllithium-induced decarboxylation of non-enolizable carboxylic acids. An anionic equivalent to the hunsdiecker reaction
作者:John P. Gilday、Leo A. Paquette
DOI:10.1016/s0040-4039(00)80532-8
日期:1988.1
Intermediate dianions formed by nucleophilic attack of methyllithium on α-phenyl or α-phenylthio carboxylate salts fragment in highly coordinating solvents to produce stabilized carbanions. Once formed, these anions may be conveniently functionalized with various electrophilic reagents.
Preparation and reactions of cyclic and acyclic allene complexes of zirconocene
作者:Jianguo Yin、W.M. Jones
DOI:10.1016/0040-4020(94)01128-m
日期:1995.4
substitution due to rapid coupling of the initally formed complex with the unreacted allene. This problem was circumvented by generating the allene complex by β-hydrogen elimination from a pre-formed sigma complex. This appears to be a potentially general way to prepare allene complexes of zirconocene if the allene precursor has no cis-vinyl hydrogen. This method has been successfully used to prepare
<i>Z</i>-Trisubstituted α,β-Unsaturated Esters and Acid Fluorides through Stereocontrolled Catalytic Cross-Metathesis
作者:Can Qin、Tobias Koengeter、Fengyue Zhao、Yucheng Mu、Fang Liu、K. N. Houk、Amir H. Hoveyda
DOI:10.1021/jacs.2c13245
日期:2023.2.15
Z-trisubstituted α-methyl, α,β-unsaturated, alkyl and aryl esters, thiol esters, and acid fluorides. Transformations are promoted by a Mo bis-aryloxide, a monoaryloxide pyrrolide, or a monoaryloxide chloride complex; air-stable and commercially available paraffin tablets containing a Mo complex may also be used. Alkyl, aryl, and silyl carboxylicesters as well as thiol esters and acid fluoride reagents
可以生成高立体异构纯度的三取代烯烃的催化交叉复分解(CM)反应很重要,但范围仍然有限。这里引入了 CM 反应,生成Z-三取代的 α-甲基、α,β-不饱和烷基酯和芳基酯、硫羟酸酯和酰基氟。 Mo双芳基氧化物、单芳基氧化物吡咯化物或单芳基氧化物氯化物复合物促进转化;也可以使用含有Mo络合物的空气稳定且市售的石蜡片。烷基、芳基和甲硅烷基羧酸酯以及硫羟酸酯和酰基氟试剂可以购买或可以一步制备。产物收率 55–95%, Z / E比为 88:12–>98:2(通常>95:5)。该方法的适用性通过香茅醇两步转化为异薄荷内酯前体(1.7 g,产率 73%, Z / E 97:3)和乙酸羊毛甾醇单步转化为 3- epi -anwuweizic 来突出。酸(产率 72%, Z / E 94:6)。其中包括 DFT 研究的结果,涉及几个最初令人费解的催化剂活性趋势,提供以下信息:(1) 关键是,由竞争性同复分解