Instituto CINQUIMA and Departamento de Química Orgánica, Facultad de Ciencias , Universidad de Valladolid , Paseo de Belén 7 , 47011 - Valladolid , Spain.
J Org Chem. 2018 May 18;83(10):5546-5557. doi: 10.1021/acs.joc.8b00567. Epub 2018 May 3.
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 nitrostyrenes or 2,3,4-trisubstituted 4 H-chromenes by reaction of the same α-amido sulfones with (phenylsulfonyl)acetonitrile in excellent diastereo- and enantioselectivities. Two polymeric thioureas and squaramides were prepared by copolymerization of the best monomeric catalysts with styrene and divinylbenzene and used for the same transformations. These polymers behave also as excellent stereoselective catalysts that can be recovered and reused for five cycles.
新型的苯乙烯基取代硫脲和噁二唑啉酮可以从商业可得的 4-羟基-3,5-二氯苯胺出发，经过三步反应得到。这些有机催化剂以高产率和优异的立体选择性促进级联反应。通过仅使用 5 mol%的催化剂负载量，有可能通过反应α-酰胺砜，得到 2,3,4-三取代的苯并吡喃，该α-酰胺砜是由水杨醛和硝基亚乙烯基砜衍生而来，或者通过反应相同的α-酰胺砜与（苯磺酰基）乙腈，得到 2,3,4-三取代的 4H-色烯，产率高且对映选择性和非对映选择性优异。两种聚合的硫脲和噁二唑啉酮是通过最佳单体催化剂与苯乙烯和二乙烯基苯的共聚制备的，并用于相同的转化。这些聚合物也表现出优异的立体选择性催化剂的行为，可以回收并重复使用五轮。
