Enamine/butadienylborane cycloaddition in the frustrated Lewis pair regime
作者:Guo-Qiang Chen、Fatma Türkyilmaz、Constantin G. Daniliuc、Christoph Bannwarth、Stefan Grimme、Gerald Kehr、Gerhard Erker
DOI:10.1039/c5ob01602a
日期:——
Piers’ borane [HB(C6F5)2]. Its reaction with a series of acetophenone derived enamines 3 resulted in the formation of the strong enamine β-carbon adduct with the borane Lewis acid (4). In contrast B–C adduct formation between the dienylborane 2a and a series of much more bulky cyclohexanone derived enamines (6) is rapidly reversible above ca. −30 °C and then leads to the formation of the [4 + 2]cycloaddition
二烯基硼烷2a是通过共轭烯炔1a与Piers's硼烷[HB(C 6 F 5)2 ]的区域选择性炔烃硼氢化制备的。它与一系列苯乙酮衍生的烯胺3的反应导致与硼烷路易斯酸(4)形成强烯胺β-碳加合物。相比之下,二烯基硼烷2a与一系列更大体积的环己酮衍生的烯胺之间的B-C加合物的形成在ca之上可快速逆转(6)。−30°C,然后形成[4 + 2]环加成产物8。DFT研究表明,该反应可能是逐步进行的,通过在二烯基硼烷末端加烯胺来生成两性离子的硼酸酯-烯烃/亚胺离子中间体,该中间体随后会快速闭合。产物8的加热导致在产物框架处的邻氨基/硼烷对中的氨基硼烷消除,从而得到相应的六氢萘产物10。随后用TEMPO(2当量)处理导致不饱和环选择性氧化,得到相应的四氢萘衍生物12。
Rhodium catalysts derived from a fluorinated phanephos ligand are highly active catalysts for direct asymmetric reductive amination of secondary amines
作者:Sophie H. Gilbert、Sergey Tin、José A. Fuentes、Tamara Fanjul、Matthew L. Clarke
DOI:10.1016/j.tet.2020.131863
日期:2021.1
An asymmetric hydrogenation of enamines is efficiently catalysed by rhodium complexed with a fluorinated version of the planar chiral paracyclophane-diphosphine ligand, Phanephos. This catalyst was shown to be very active, with examples operating at just 0.1 mol% of catalyst. This catalyst was then successfully adapted to Direct AsymmetricReductive Amination, leading to the formation of several tertiary
Asymmetric Copper-Catalyzed Propargylic Substitution Reaction of Propargylic Acetates with Enamines
作者:Ping Fang、Xue-Long Hou
DOI:10.1021/ol901891u
日期:2009.10.15
Enamines served as carbon-nucleophiles for the first time in the Cu-catalyzed asymmetricpropargylicsubstitutionreaction of propargylicacetates, providing corresponding chiral β-ethynyl-substituted ketones in high yields and in good to high enantioselectivity.
Internal Adduct Formation of Active Intramolecular C<sub>4</sub>-bridged Frustrated Phosphane/Borane Lewis Pairs
作者:Xiaowu Wang、Gerald Kehr、Constantin G. Daniliuc、Gerhard Erker
DOI:10.1021/ja413060u
日期:2014.2.26
The tetramethylene-bridged PMes2/B(C6F5)2 frustratedLewispair (FLP) 8 was prepared by hydroboration of Mes2P-(CH2)2CH═CH2 with HB(C6F5)2. It is an active FLP that splits dihydrogen under mild conditions and, consequently, serves as a metal-free hydrogenation catalyst for a variety of substrates. It also reacts typically with terminal acetylenes. The C4-bridged FLP 23 was prepared by HB(C6F5)2 hydroboration
Frustrated Lewis Pair Chemistry Derived from Bulky Allenyl and Propargyl Phosphanes
作者:Christoph Rosorius、Jennifer Möricke、Birgit Wibbeling、Alison C. McQuilken、Timothy H. Warren、Constantin G. Daniliuc、Gerald Kehr、Gerhard Erker
DOI:10.1002/chem.201502493
日期:2016.1.18
underwent rapid phosphane/borane (P/B) frustrated Lewis pair (FLP) reactions under mild conditions. Compound 2 c reacted with nitric oxide (NO) to give the persistent FLP NO radical 11. The systems 2 b,c cleaved dihydrogen at room temperature to give the respective phosphonium/hydridoborate products 13 b,c. Compound 13 c transferred the H+/H− pair to a small series of enamines. Compound 13 c was also