A Highly Tunable Stereoselective Olefination of Semistabilized Triphenylphosphonium Ylides with <i>N</i>-Sulfonyl Imines
作者:De-Jun Dong、Hai-Hua Li、Shi-Kai Tian
DOI:10.1021/ja910238f
日期:2010.4.14
The Wittigreaction involving direct olefination of triphenylphosphonium ylides (Ph(3)P horizontal lineCHR) with aldehydes is arguably the most often used method for alkene synthesis, but in general it yields mixtures of Z- and E-alkenes for semistabilized triphenylphosphonium ylides (R = aryl or vinyl). We have developed a simple and efficient protocol to improve the stereoselectivity significantly
Transition-Metal-Free Sulfuration/Annulation of Alkenes: Economical Access to Thiophenes Enabled by the Cleavage of Multiple C–H Bonds
作者:Liang Chen、Hao Min、Weilan Zeng、Xiaoming Zhu、Yun Liang、Guobo Deng、Yuan Yang
DOI:10.1021/acs.orglett.8b03078
日期:2018.12.7
and transition-metal-free strategy for the synthesis of thiophenes from substituted buta-1-enes with potassium sulfide has been presented. The reaction achieves double C–Sbondformations via cleavage of multiple C–H bonds and provides an efficientapproach to access various functionalized thiophenes. Moreover, the strategy can also be used for the synthesis of thiophenes from 1,4-diaryl-1,3-dienes.
Catalysis by ionic liquids: cyclopropyl carbinyl rearrangements catalyzed by [pmim]Br under organic solvent free conditions
作者:Brindaban C. Ranu、Subhash Banerjee、Arijit Das
DOI:10.1016/j.tetlet.2005.12.003
日期:2006.2
Aryl substituted cyclopropylcarbinol derivatives undergo stereoselective rearrangements catalyzed by the ionic liquid, 1-methyl-3-pentylimidazolium bromide, under sonication, without any organic solvent, to produce the substituted conjugated all-trans-butadienes.
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。
Synthesis of 1-aryl-2,3-diaroyl cyclopropanes from 1,3,5-triaryl-1,5-diketones and their transformation into E,E-1,4-diaryl-1,3-butadienes
作者:Kashpar John Britto、Maniarasu Meenakshi、Kannupal Srinivasan
DOI:10.1039/d4ra02525c
日期:——
A new method for the synthesis of 1-aryl-2,3-diaroyl cyclopropanes has been developed by iodine/DBU-mediated cyclization of 1,3,5-triaryl-1,5-diketones. The alcohols derived by the reduction of these cyclopropanes, when treated with conc. HCl, afforded a series of 1,3-dienes through cyclopropyl ring-opening and subsequent fragmentation. Overall, the synthetic sequence represents a new non-Wittig methodology