Chiral Bifunctional Thioureas and Squaramides and Their Copolymers as Recoverable Organocatalysts. Stereoselective Synthesis of 2-Substituted 4-Amino-3-nitrobenzopyrans and 3-Functionalized 3,4-Diamino-4<i>H</i>-Chromenes
作者:José M. Andrés、Alicia Maestro、María Valle、Rafael Pedrosa
DOI:10.1021/acs.joc.8b00567
日期:2018.5.18
Novel styryl-substituted thioureas and squaramides were obtained in three steps from commercially available 4-hydroxy-3,5-dichloroaniline. These organocatalysts promote cascade reactions in high yields and excellent stereoselection. By using only a 5 mol % loading of catalyst, it is possible to obtain 2,3,4-trisubstituted benzopyrans by reaction of α-amido sulfones derived from salicyladehydes and
从市售的4-羟基-3,5-二氯苯胺中分三步获得了新的苯乙烯基取代的硫脲和方酸酰胺。这些有机催化剂以高收率和出色的立体选择性促进级联反应。通过仅使用5mol%的催化剂负载量,可以通过衍生自水杨醛和硝基苯乙烯的α-酰胺基砜或2,3,4-三取代的4 H反应获得2,3,4-三取代的苯并吡喃。通过相同的α-酰胺基砜与(苯磺酰基)乙腈的反应,具有非对映选择性和对映选择性。通过最好的单体催化剂与苯乙烯和二乙烯基苯的共聚反应,制备了两种聚合的硫脲和方胺,并用于相同的转化。这些聚合物还具有出色的立体选择性催化剂的作用,可以回收并重复使用五个循环。