Highly Diastereo- and Enantioselective Vinylogous Mannich Reactions of Fluorinated Aldimines with Siloxyfurans
作者:Qian-Yi Zhao、Zhi-Liang Yuan、Min Shi
DOI:10.1002/adsc.201000843
日期:2011.3.7
A highly regio‐ and enantioselective asymmetric vinylogousMannichreaction of readily available fluorinatedaldimines bearing a chiral auxiliary [(S)‐1‐phenylethyl group] with siloxyfurans to afford chiral fluorine‐containing γ‐butenolide or γ‐lactone derivatives has been developed in the presence of silver acetate (10 mol%) and axially chiral phosphine‐oxazoline ligand L1 (11 mol%). In most cases
New peptidomimetics featuring CH(RF)NH units, having different degree of fluorination, as peptide-bond surrogates have been synthesized. The key step in the synthesis consists of a stereoselective aza-Michael addition of chiral α-amino acid esters to β-fluoroalkyl-α-nitroethenes. The diastereoselection of the process was influenced by the electronegativity, rather than by the steric bulk, of the fluorinated residue RF in β-position of the nitroalkene acceptors. Replacement of a single F atom of RF by a hydrogen or methyl group brings about a dramatic drop of stereocontrol, whereas Br, Cl, and CF3, albeit bulkier than F, provide poorer results in terms of stereocontrol.
Copper(I)-Catalyzed Asymmetric 1,3-Dipolar Cycloaddition of Azomethine Ylides with Fluorinated Imines: The Expanded Scope and Mechanism Insights
作者:Liang Wei、Qing-Hua Li、Chun-Jiang Wang
DOI:10.1021/acs.joc.8b01743
日期:2018.10.5
The mechanism of the Cu(I)/(S,Rp)-PPFOMe-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with fluorinated aldimines has been studied using labeling experiments, control experiments, and linear effect experiments, which clearly ruled out the 1,3-DC/epimerization pathways and explained the unusal exo′-selective stereochemistry. This protocol allows for the preparation of a series of highly functionalized
使用标记实验,对照实验和线性效应实验研究了Cu(I)/(S,R p)-PPFOMe催化的1,3-偶极环偶氮亚甲基与氟化亚胺的加成反应的机理,明确排除了1,3- DC /差向异构化途径和解释了此项特殊的外切' -选择性的立体化学。该方案允许以良好的产率和优异的立体选择性制备一系列高度官能化的氟化咪唑烷。而且,目前的方法已经成功地扩展到通过内含物合成具有挑战性的,带有CF 3的季立构中心的咪唑烷类化合物。在相同的反应条件下,用三氟化酮亚胺对甲亚胺烷基化物进行1,3-DC选择性合成。
Synthesis of fluorinated 3-pyrrolines and pyrroles via [3+2] annulation of N-aryl fluorinated imines with allenoates catalyzed by phosphine
A phosphine-catalyzed [3 + 2] annulation of N-aryl fluorinated imines with allenoates is reported. A series of fluorinated pyrrolines is obtained in moderate yield, which are further transformed to fluorinated pyrroles via dehydro-aromatization by DDQ in high to excellent yield. The reaction mechanism is also discussed.
Asymmetric Organocatalyzed Friedel–Crafts Reaction of Trihaloacetaldehydes and Phenols
作者:David Svestka、Jan Otevrel、Pavel Bobal
DOI:10.1002/adsc.202200180
日期:2022.7.5
Herein we report the asymmetric organocatalyzed method for the Friedel–Craftsreaction between activatedphenols and trihaloacetaldehydes. A three-phase screening including 41 compounds was employed to identify a catalyst structure based on 3,5-dinitrobenzamide of 9-amino-epi-cinchonidine as the lead catalytic molecule. Under the optimized reaction conditions, the above catalyst offered trihalohydroxyalkylated