Allylation of Aldehydes Promoted by the Cerium(III) Chloride Heptahydrate/Sodium Iodide System: the Dependence of Regio- and Stereocontrol on the Reaction Conditions
The cerium(III) chloride heptahydrate/sodium iodide complex (CeCl3 ⋅ 7 H2O/NaI) acts as a useful promoter in the carbon-carbonbond forming reaction by addition of allyltributylstannanes to aldehydes. The reaction of 2-butenyltributylstannane shows that the regio- and the stereochemical outcomes depend on the reaction conditions. When the promoter is adsorbed on a solid support (aluminum oxide), a
铈(III)七水合氯化/碘化钠复合物(加入CeCl 3 ⋅7 H 2 O / NAI)作为在碳-碳键形成通过加入allyltributylstannanes醛的反应的有用的启动子。2-丁烯基三丁基锡烷的反应表明区域和立体化学结果取决于反应条件。当促进剂吸附在固体载体(氧化铝)上时,在无溶剂条件下会观察到非常普遍的γ加合物形成。相反,当反应在乙腈作为溶剂中进行时,α-加合物占优势。在最后一种情况下,观察到完全的立体控制,以高几何纯度获得较不稳定的(Z)-异构体。
syn-Selective crotylation of aldehydes using bismuth-crotyl bromide-(1-butyl-3-methylimidazolium bromide) combination: some synthetic applications
作者:Dibakar Goswami、Mrunesh R. Koli、Sucheta Chatterjee、Subrata Chattopadhyay、Anubha Sharma
DOI:10.1039/c7ob00626h
日期:——
The Bi-[bmim][Br] combination has been found to offer high syn-selectivity in the crotylation of aldehydes with crotylbromide using practically stoichiometric amounts of the reagents. The room temperature ionic liquid (RTIL), [bmim][Br], activated Bi metal in the presence of oxygen to produce crotylbismuthdibromide, which reacted with the aldehydes at room temperature. The major anti–syn diastereomeric
<i>anti</i>-Diastereo- and Enantioselective Carbonyl Crotylation from the Alcohol or Aldehyde Oxidation Level Employing a Cyclometallated Iridium Catalyst: α-Methyl Allyl Acetate as a Surrogate to Preformed Crotylmetal Reagents
作者:In Su Kim、Soo Bong Han、Michael J. Krische
DOI:10.1021/ja808857w
日期:2009.2.25
catalyst generated in situ from [Ir(cod)Cl](2), 4-cyano-3-nitrobenzoic acid and the chiral phosphine ligand (S)-SEGPHOS, alpha-methyl allyl acetate couples to alcohols 1a-1j with complete levels of branched regioselectivity to furnish products of carbonyl crotylation 3a-3j, which are formed with good levels of anti-diastereoselectivity and exceptional levels of enantioselectivity. An identical set of optically
在使用由[Ir(cod)Cl](2)、4-氰基-3-硝基苯甲酸和手性膦配体(S)-SEGPHOS原位生成的邻位环金属化铱催化剂进行转移氢化的条件下,α-甲基乙酸烯丙酯与具有完全支化区域选择性水平的醇1a-1j偶联,提供羰基巴豆酰化产物3a-3j,形成的产物具有良好水平的反非对映选择性和异常水平的对映选择性。在相同的条件下,但使用异丙醇作为末端还原剂,可以从相应的醛2a-2j得到一组相同的光学富集的羰基巴豆酰化产物3a-3j。旨在探索立体选择起源的实验建立了 (R)-乙酸酯和经 (S)-SEGPHOS 修饰的铱催化剂的匹配电离模式,以及烯丙基乙酸酯的可逆电离和快速 pi 面相互转化。在CC键形成之前产生吡啶基中间体。此外,还证明了在羰基加成之前的快速醇-醛氧化还原平衡。因此,在不存在任何化学计量金属试剂或化学计量金属副产物的情况下,实现了醇或醛氧化水平的反非对映选择性和对映选择性羰基巴豆酰化。
Iridium-Catalyzed Hydrohydroxyalkylation of Butadiene: Carbonyl Crotylation
作者:Jason R. Zbieg、Takeo Fukuzumi、Michael J. Krische
DOI:10.1002/adsc.201000599
日期:2010.10.4
cyclometallated iridium catalyzed derived from allyl acetate, 4-methoxy-3-nitrobenzoic acid and BIPHEP (2,2'-bis(diphenylphosphino)biphenyl) results in hydrogen transfer to generate aldehyde-allyliridium pairs, which engage in C-Ccoupling to form products of carbonyl crotylation. Under related conditions using 1,4-butanediol as hydrogen donor, butadiene reductively couples to aldehydes 2e-2g and 2i to furnish