固定化的无金属催化剂的使用为在流动模式下开发可持续流程提供了独特的可能性。在连续流动条件下,首次进行了具有挑战性的分子间有机催化的醛类对映选择性烷基化反应。通过使用填充有容易获得的对映体纯的咪唑啉酮的填充床反应器,用三种不同的阳离子亲电试剂处理不同的醛。与1,3-苯并二硫代四氟硼酸酯进行醛类的有机催化醛的α-烷基化反应时,具有优异的对映选择性,在某些情况下甚至比在烧瓶法中获得的对映选择性更好(在25°C时,ee高达95% ),并且生产率高(超过3800) h -1),因此表明催化反应器可以连续生产对映体富集的化合物。用阮内镍提供的对映异构体富集的α-甲基衍生物(活性药物成分和天然产物的关键中间体)处理烷基化产物。
Direct α-Alkylation of Aldehydes by Brønsted-Acid Catalysis
作者:Xiangrong Zhu、Ting Wang、Qixiang Guo
DOI:10.1002/cjoc.201100464
日期:2012.1
A Brønstedacid catalyzed directalkylation reaction of aldehydes was described. The 3,5‐dinitrobenzoic acid promoted the reaction between aldehydes and diarylmethanols to afford the corresponding alkylation products with middle to high yields (up to 91% yield).
The acid free asymmetric intermolecular α-alkylation of aldehydes in fluorinated alcohols
作者:Jian Xiao、Kai Zhao、Teck-Peng Loh
DOI:10.1039/c2cc30261f
日期:——
The acid free asymmetric intermolecular α-alkylation of aldehydes with alcohols has been discovered using trifluoroethanol as solvent. This unprecedented system affords the enantioenriched functionalized primary alcohols (after NaBH4 reduction) in high yields and good to excellent enantioselectivities with wide substrate scope in the absence of any acid additive.
Brønsted Acid Catalyzed α-Alkylation of Aldehydes with Diaryl Methyl Alcohols
作者:Chong Xing、Hui Sun、Junmin Zhang、Guohui Li、Yonggui Robin Chi
DOI:10.1002/chem.201102623
日期:2011.10.24
A proton does the two jobs: Brønsted acids alone catalyze the α‐alkylation of aldehydes with diaryl alcohols. In this type of transformation, the acid‐catalysis approach offers a broader substrate scope compared to the previously used enamine catalysis methods. The acid plays two important roles: one is to mediate the alcohol dehydration for carbocation formation; the other is to accelerate the rate‐determining