A Facile Synthesis of 1,1-Difluoroallenes from Commercially Available 1,1,1-Trifluoro-2-iodoethane
作者:Junji Ichikawa、Ken Oh、Kohei Fuchibe
DOI:10.1055/s-0030-1258438
日期:2011.3
1,1-Difluoroallenes are synthesized in good yield via zinc-promoted 1,2-elimination of 3,3-difluoro-2-iodoallylic acetates, which are prepared by the reaction of aldehydes or ketones with 1-iodo-2,2-difluorovinyllithium, generated from commercially available 1,1,1-trifluoro-2-iodoethane.
In this study, 1,1-difluoroallenes underwent a regioselective [2+3] cycloaddition with nitrile oxides and imine oxides in the presence of a AuCl catalyst. (E)-4-Alkylidene-5,5-difluoroisoxazolines and -isoxazolidines were obtained in regioselective and diastereoselective manners by employing aurated difluoroallylic cation intermediates. The synthesized 5,5-difluoroisoxazolines were readily aromatized
在这项研究中,1,1-二氟丙二烯在 AuCl 催化剂存在下与氧化腈和氧化亚胺发生区域选择性 [2+3] 环加成反应。( E )-4-亚烷基-5,5-二氟异恶唑啉和5,5-二氟异恶唑烷是通过使用含金二氟烯丙基阳离子中间体以区域选择性和非对映选择性方式获得的。合成的 5,5-二氟异恶唑啉很容易通过脱氟化氢或烯丙基氟取代来芳构化,得到 5-氟异恶唑。
Multi-substituted trifluoromethyl alkene construction <i>via</i> gold-catalyzed fluoroarylation of <i>gem</i>-difluoroallenes
fluoroarylation of 1,1-difluoroallenes with a cost-effective nucleophilic fluoride reagent and aryldiazonium salts is reported. This visible light promoted gold-catalyzed reaction allows a stereo- and regioselective incorporation of both the fluorine atom and aryl group, enabling a straightforward construction of multi-substituted trifluoromethyl alkenes. Under the mild reaction conditions, a nice tolerance of diverse