Palladium-Catalyzed Stereoselective Synthesis of (E)-Stilbenes via Organozinc Reagents and Carbonyl Compounds
作者:Jin-Xian Wang、Kehu Wang、Lianbiao Zhao、Hongxia Li、Ying Fu、Yulai Hu
DOI:10.1002/adsc.200606016
日期:——
In the presence of a catalytic amount of PdCl2(PPh3)2 and a silylating agent, organozinc halides reacted with carbonylcompounds to give the corresponding (E)-stilbenes in good to excellent yields under mild conditions. The reaction mechanism is briefly discussed.
One-Pot Intermolecular Reductive Cross-Coupling of Deactivated Aldehydes to Unsymmetrically 1,2-Disubstituted Alkenes
作者:Anna I. Arkhypchuk、Nicolas D’Imperio、Sascha Ott
DOI:10.1021/acs.orglett.8b01754
日期:2018.9.7
MesP(Li)TMS, and an aldehyde affords Mes-phosphaalkenes which, upon methanol addition and P-oxidation, react with a second carbonyl compound site specifically to produce unsymmetric alkenes. The E/Z selectivity of the one-pot cross coupling is largely determined by the electronic nature of the aryl substituent of the first aldehyde, with electron-donating groups giving rise to increased amounts of Z-alkenes.
Divergent Rearrangements of Cyclopropyl-Substituted Fluoroepoxides Involving C–F Bond Cleavage and Formation
作者:Tao Luo、Rui Zhang、Wei Zhang、Xiao Shen、Teruo Umemoto、Jinbo Hu
DOI:10.1021/ol403644n
日期:2014.2.7
Unprecedented divergent rearrangements of cyclopropyl-substituted fluoroepoxides are reported. In the presence of a catalytic amount of benzoic acid, cyclopropyl-substituted fluoroepoxides efficiently undergo 1,5-fluorine migration. However, when the fluoroepoxides are heated with K2CO3 at 60 °C, 1,2-fluorine migration occurs. The 1,5-fluorine migration is believed to proceed via a carbocation intermediate
据报道,环丙基取代的氟环氧化物发生了前所未有的发散重排。在催化量的苯甲酸存在下,环丙基取代的氟环氧化物有效地经历了1,5-氟的迁移。然而,当将氟环氧化物与K 2 CO 3在60°C下加热时,会发生1,2-氟迁移。据信1,5-氟迁移通过碳正离子中间体进行,而1,2-氟迁移可能涉及紧密的离子对中间体或通过协同过程进行。
Iridium-Catalyzed Selective <i>trans</i>-Semihydrogenation of 1,3-Enynes with Ethanol: Access to (<i>E,E</i>)-1,4-Diarylbutadienes
precatalyst and tBuNH2 as the cocatalyst. This catalyst system provides an efficient and atom-economical access to unsymmetrical (E,E)-1,4-diarylbutadienes with high yields and stereoselectivities. Monitoring the process revealed that a sequence of cis-semihydrogenation of the triple bond of 1,3-enynes (to form (E,Z)-butadienes) and (E,Z)-to-(E,E) isomerization occurs to form (E,E)-butadienes.
使用新的 (PCN)Ir 配合物作为预催化剂和t BuNH 2作为助催化剂,开发了以乙醇为氢源的 1,3-烯炔的反式半氢化反应。该催化剂体系以高产率和立体选择性提供了一种高效且原子经济地获得不对称 ( E , E )-1,4-二芳基丁二烯的途径。监测过程显示,1,3-烯炔的三键顺式半氢化(形成 ( E , Z )-丁二烯)和 ( E , Z ) 到-( E , E ) 异构化形成( , _E )-丁二烯。
Base-promoted direct <i>E</i>-selective olefination of organoammonium salts with sulfones toward stilbenes and conjugated 1,3-dienes
deaminative olefination of organoammonium salts was developed. Only mediated by KOtBu, a series of benzyl and cinnamyl ammonium salts reacted smoothly with sulfones, producing the valuable stilbenes and related 1,3-diene derivatives in good to high yields with good functional group tolerance and excellent E-selectivity. With this developed method, biologically active resveratrol and DMU-212 were also successfully
开发了一种碱促进的有机铵盐直接脱氨基烯化。仅由 KO t Bu 介导,一系列苄基和肉桂基铵盐与砜类顺利反应,以良好至高收率生产有价值的二苯乙烯和相关的 1,3-二烯衍生物,具有良好的官能团耐受性和优异的E选择性。利用该方法,还成功制备了具有生物活性的白藜芦醇和DMU-212,进一步证明了该反应的实用性。