Chiral spiro phosphoric acid-catalysed enantioselective reaction of ketenes with N–H pyrroles
作者:Qian-Yi Wang、Teng-Fei Liu、Li-Feng Chu、Yun Yao、Chong-Dao Lu
DOI:10.1039/d1cc05307h
日期:——
In the presence of a chiral spiro phosphoric acid catalyst, the asymmetric reaction of disubstituted ketenes with N–H pyrroles occurred to afford enantioenriched C-acylated pyrroles bearing α-stereogenic carbon centres. The described reaction constitutes a rare example of a catalytic asymmetric reaction of ketenes with carbon-based nucleophiles.
Phosphine-Catalyzed Asymmetric Synthesis of β-Lactones from Disubstituted Ketenes and Aldehydes
作者:Shi Chen、Mukulesh Mondal、Ahmad A. Ibrahim、Kraig A. Wheeler、Nessan J. Kerrigan
DOI:10.1021/jo500486e
日期:2014.6.6
general catalytic procedure for the formation of β-lactones bearing two stereogenic centers, from disubstituted ketenes and achiral aldehydes. BINAPHANE was found to display excellent enantioselectivity (≥90% ee for eight examples) and good diastereoselectivity (≥90:10 for 13 examples) in catalyzing the formation of β-lactones bearing two stereogenic centers from achiral aldehydes (both aromatic and aliphatic)
在本文中,我们描述了由双取代的烯酮和非手性醛形成带有两个立体中心的β-内酯的一般催化程序。发现BINAPHANE在催化由非手性醛(芳族和脂族)和两个非手性醛形成带有两个立构中心的β-内酯时,表现出优异的对映选择性(对于8个实例≥90%ee)和良好的非对映选择性(对于13个实例≥90:10)。烷基芳基烯酮或二烷基烯酮。在这些反应中观察到偏好形成反式非对映异构体。对于那些其中BINAPHANE失败作为催化剂的反应,三Ñ发现丁基丁基膦是一种有效的非手性亲核催化剂,在外消旋β-内酯的形成中具有良好的收率和非对映选择性。通过31 P NMR光谱监测反应并与在膦催化的乙烯酮均二聚反应中观察到的先前表征的中间体进行比较,获得了有关烯醇中间体参与反应机理的证据。
Phosphine-catalyzed stereoselective dimerizations of ketenes
作者:Ahmad A. Ibrahim、Pei-Hsun Wei、Gero D. Harzmann、Divya Nalla、Mukulesh Mondal、Kraig A. Wheeler、Nessan J. Kerrigan
DOI:10.1016/j.tet.2020.131838
日期:2021.1
Full details of optimisation studies of the phosphine-catalyzed ketene homodimerization reaction and the detailed development of an asymmetric variant are discussed. Studies towards the development of a phosphine-catalyzed ketene heterodimerization reaction are revealed. A discussion of possible reaction mechanisms for the dimerization reactions, supported by spectroscopic analysis of intermediates
Josiphos-Catalyzed Asymmetric Homodimerization of Ketoketenes
作者:Ahmad A. Ibrahim、Pei-Hsun Wei、Gero D. Harzmann、Nessan J. Kerrigan
DOI:10.1021/jo101867m
日期:2010.11.19
phosphine-catalyzed homodimerization of ketoketenes that provides access to a variety of highlysubstitutedketoketenedimerβ-lactones (11 examples) is reported. The Josiphos catalytic system displays good to excellent enantioselectivity (up to 96% ee). Ring-opening reactions of the enantioenriched ketoketenedimers were also carried out to access 1,3-diketones, enolesters, and β-hydroxyketones with good
Asymmetric synthesis of enantioenriched α-allyl esters through Pd(BINAPHANE)-catalysed allylation of disubstituted ketenes
作者:Ahmad A. Ibrahim、Stephen C. J. O’Reilly、Margot Bottarel、Nessan J. Kerrigan
DOI:10.1039/d4cc00057a
日期:2024.3.19
Pd2dba3·CHCl3 (2.5 mol%)-BINAPHANE (5 mol%) was used to promote the first catalytic enantioselective allylation of disubstituted ketenes to give α-allyl esters. The ester products were formed in good to excellent yields (61–93% yield for 13 examples, 16 examples in all), with moderate to good enantioselectivity (68–80% ee for 7 examples).