BF<sub>3</sub>·Et<sub>2</sub>O-Catalyzed Direct Carbon−Carbon Bond Formation of α-EWG Ketene-(<i>S</i>,<i>S</i>)-Acetals and Alcohols and Synthesis of Unsymmetrical Biaryls
作者:Qian Zhang、Shaoguang Sun、Jianglei Hu、Qun Liu、Jing Tan
DOI:10.1021/jo061775e
日期:2007.1.1
efficient BF3·OEt2-catalyzed formal dehydration C−C coupling reaction between readily available α-EWG ketene-(S,S)-acetals and various alcohols via direct substitution of the hydroxy group in alcohols has been developed. On the basis of this C−C coupling reaction, a series of alkylated α-EWG ketene-(S,S)-acetals and functionalized 1,4-pentanedienes were prepared in high to excellent yields and the unsymmetrical
Unexpected Hydrobromic Acid-Catalyzed CC Bond-Forming Reactions and Facile Synthesis of Coumarins and Benzofurans Based on Ketene Dithioacetals
作者:Hongjuan Yuan、Mang Wang、Yingjie Liu、Lili Wang、Jun Liu、Qun Liu
DOI:10.1002/chem.201002107
日期:2010.12.3
Hydrobromic acid was found to be a unique catalyst in CC bond‐forming reactions with ketene dithioacetals. Distinctly different from other acids (including Lewis and Brønsted acids), the remarkable catalytic performance of hydrobromic acid in catalytic amounts was observed in the “acid”‐catalyzed reactions of readily available functionalized ketene dithioacetals 1 with various electrophiles. Under
氢溴酸被发现是在C独特催化剂与烯酮二硫C键形成反应。与其他酸(包括路易斯酸和布朗斯台德酸)明显不同,氢溴酸在催化量上的显着催化性能在易于获得的官能化乙烯酮二硫缩醛1与各种亲电试剂的“酸”催化反应中观察到。在0.1当量的氢溴酸的催化下,1与羰基化合物2 a – l的反应生成多官能化的戊-1,4-二烯3或共轭二烯4产量高到极好。该反应在乙烯酮二硫缩醛1和羰基化合物2上均具有宽范围的取代基。这种有效的CC键形成方法的应用是在温和的,无金属的条件下,通过氢溴酸1与水杨醛2 m - o和对苯醌6 a - d的反应生成香豆素5和苯并呋喃7。, 分别。根据抗衡离子的性质,形成了一种新的反应性物种,即一种硫稳定的碳鎓叶立德,这被提议作为氢溴酸独特催化的关键中间体。
Palladium‐Catalyzed Oxidative Cross‐Coupling of α‐Cyanoketene Dithioacetals with Olefins
Efficient palladium‐catalyzedcross‐coupling reactions of the internal olefinsα‐cyanoketenedithioacetals with a variety of olefins were achieved in dioxane/HOAc/DMSO (9:3:1 v/v/v) under air atmosphere or by means of AgOAc as the terminal oxidant. Electron‐deficient terminal olefins reacted to form the linear diene derivatives with air as the oxidant. Styrenes underwent the cross‐coupling to give both
在二恶烷/ HOAc / DMSO(9:3:1 v / v / v)中或在空气中或通过AgOAc的方式,在内部空气中钯催化的α-氰基碳烯二硫缩醛与各种烯烃的高效交叉偶联反应得以实现。 终端氧化剂。缺电子的末端烯烃与空气反应形成线性二烯衍生物。当使用AgOAc作为氧化剂时,苯乙烯会进行交叉偶联,以生成直链和支链的二烯。未活化的环状和线性内烯烃底物都在空气中催化量的苯醌存在下反应,生成跳过的二烯。X射线晶体学在结构上证实了典型产品。
Three-Component Reactions of Ketene Dithioacetals, Aldehydes, and Arenesulfinic Acids: Facile Synthesis of Allylic Sulfones
作者:Deqiang Liang、Wenzhong Huang、Lin Yuan、Yinhai Ma、Liping Ouyang、Yuqin Rao、Yuxian Yang
DOI:10.1080/00397911.2013.879315
日期:2014.7.3
Abstract A facile and efficient synthesis of allylic sulfones via sulfuric acid–mediated three-component reactions of easily available ketenedithioacetals, aldehydes, and arenesulfinic acids is presented. The reaction features low cost and good yields. GRAPHICAL ABSTRACT
TiCl4 mediated Michael addition reactions of α-cyanoketene-S,S-acetals with enones
作者:Yanbing Yin、Qian Zhang、Jia Li、Shaoguang Sun、Qun Liu
DOI:10.1016/j.tetlet.2006.06.098
日期:2006.8
Titaniumtetrachloridepromoted Michael addition reactions of α-cyanoketene-S,S-acetals 1 with enones 2 have been developed. The polyfunctionalized 2-[1,3]dithiolan-2-ylidene-3-substituted-5-oxo-5-substituted-pentanenitriles 3 were obtained in good to high yields and the corresponding mechanism was also described.