硫脲衍生物有机催化蒽酮与硝基烯烃的不对称Michael加成反应

将硫脲衍生物用于有机催化蒽酮和β-硝基烯烃的不对称Michael加成反应.考察溶剂、温度及催化剂用量等对反应催化性能的影响.结果表明,最佳催化条件为5%(摩尔百分数)催化剂1f,二氯甲烷为溶剂,室温反应.得到了80%~97%的化学产率和最高达99%ee的对映选择性.     

有机催化丙二酸酯与β-硝基烯烃的不对称Michael加成反应

将金鸡纳生物碱衍生物用于催化丙二酸酯和β-硝基芳基乙烯的不对称Michael加成反应。考察溶剂、温度及催化剂用量对反应催化性能的影响。结果表明,最佳催化条件为5 mol%催化剂1e,甲苯为溶剂,0℃反应。得到了86～93%的化学产率和最高达99%ee的对映选择性。     

蒽酮与β-硝基苯乙烯的不对称Michael加成反应

不对称催化Michael加成反应是一类重要的形成碳—碳键的反应,以蒽酮作为亲核试剂的不对称Michael反应报道甚少.以手性伯胺硫脲作为催化剂,对蒽酮与硝基苯乙烯的不对称有机催化Michael加成反应进行了研究.实验结果表明,所用的伯胺硫脲均具有较好的催化活性(80%～95%收率),其中硫脲4a得到了较高的对映选择性.对反应条件进行优化后,以乙醚为溶剂,使用5%摩尔分数催化剂4a和苯甲酸,研究了多个硝基苯乙烯类底物和蒽酮的Michael加成反应,获得了优异的化学收率(95%～98%)和较好的对映选择性(最高86%ee).     

有机催化不对称Michael加成反应

有机催化的不对称合成反应是目前研究最为活跃的领域之一. 不对称Michael加成反应是合成众多重要的手性合成子和药物中间体的有效手段. 目前报道的催化Michael加成反应的有机催化剂主要有脯氨酸及其衍生物、手性咪唑啉酮、手性(硫)脲、金鸡纳碱衍生物等. 对各类有机催化剂在有机催化不对称Michael加成反应中的应用, 以及不对称诱导反应的机理、催化剂分子结构及反应条件对其催化活性和不对称诱导作用的影响进行了评述.     

β-硝基丙烯酸酯与芳胺化合物的Michael加成反应研究

以β-硝基丙烯酸酯为底物,在无催化剂的条件下与芳胺化合物通过Michael加成反应,高选择性地合成了19个β-硝基-α-氨基丙酸酯类化合物(3a~3s, 3i~3s为新化合物,其结构经¹H NMR, ¹³C NMR和HR-MS（ESI）表征。并以手性BINOL磷酸为催化剂,初步探索了该反应的不对称催化,以85%收率和36%ee合成了产物3g。     

4-羟基香豆素与β-硝基烯烃的不对称Michael加成/环化串联反应

将金鸡纳碱衍生催化剂用于有机催化4-羟基香豆素和β-硝基芳基乙烯的不对称Michael加成/环化串联反应.在0.1 mmol底物用量条件下,筛选出最佳的催化剂体系为:10 mol％催化剂1g,200 mg 3?分子筛,三氯甲烷(1 mL)为溶剂,室温反应,以60～75％的产率和最高达92％的对映选择性获得了手性二氢呋喃...     

手性方酰胺催化巴比妥酸和硝基烯的不对称Michael加成反应

用手性环己二胺衍生的方酰胺催化1,3-二甲基巴比妥酸和硝基烯的不对称Michael加成反应,合成了一系列新型巴比妥衍生物,其结构经¹H NMR和¹³C NMR表征。并考察了底物结构对反应收率和立体选择性的影响。结果表明：该反应可获得较高的收率(80%~100%)和中等至良好的对映选择性(ee 43%~90%)。     

硫脲催化硝基烯与硫叶立德的不对称Michael加成反应

基于密度泛函理论研究了氯代苯基硫脲催化的硝基苯乙烯与硫叶立德的Michael加成反应,确定了控制反应立体选择性的C―C键形成步骤的过渡态结构,计算了过渡态的相对能量和反应势垒,弄清了硫脲催化的微观反应机理,探讨了硫脲催化性能的微观本质.结果表明,反应有利于反式Michael加成产物的形成,硫脲在反应中作为质子给体,首先与质子受体硝基苯乙烯形成双氢键配合物,通过授受体间的电荷转移活化硝基苯乙烯的β-C原子增强其亲电性,有利于硫叶立德的亲核进攻.     

有机催化异氰基乙酸甲酯与芳香醛亚胺的不对称Mannich反应

将金鸡纳生物碱衍生物用于有机催化异氰基乙酸甲酯与芳香醛亚胺的不对称Mannich反应。 考察溶剂、温度及催化剂用量对反应催化性能的影响。 结果表明,最佳催化条件为摩尔分数10%催化剂1b,甲苯为溶剂,4A型分子筛,室温反应。 产物产率为55%~80%,对映选择性最高达82%ee(对映体过量值)和非对映选择性(dr)达到>99：1。     

不对称催化的有机锌试剂对酮的加成反应研究进展

按照手性配体的结构类型分类, 综述了近年来有机锌试剂对酮、α-酮酯等化合物的不对称加成反应的研究进展, 对高效、高选择性的手性配体在该类反应中的应用进行了重点评述.     

Stereodivergent Organocatalytic Intramolecular Michael Addition/Lactonization for the Asymmetric Synthesis of Substituted Dihydrobenzofurans and Tetrahydrofurans

A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported. Commercially available (S)‐(?)‐tetramisole hydrochloride gives products with high syn diastereoselectivity in excellent enantioselectivity (up to 99:1 d.r._syn/anti, 99 % ee_syn), whereas using a cinchona alkaloid derived catalyst gives the corresponding anti‐diastereoisomers as the major product (up to 10:90 d.r._syn/anti, 99 % ee_anti).     

Organocatalyzed Cascade Aza‐Michael/Michael Addition for the Asymmetric Construction of Highly Functionalized Spiropyrazolone Tetrahydroquinolines

An organocatalyzed diastereo‐ and enantioselective cascade aza‐Michael/Michael addition of 2‐tosylaminoenones to unsaturated pyrazolones has been developed to afford novel chiral spiropyrazolone tetrahydroquinolines containing three contiguous stereocenters. This cascade reaction proceeded well with 2 mol % chiral bifunctional tertiary amine squaramide catalyst to give the desired products in excellent yields (up to 99 %) with excellent diastereoselectivity (up to >25:1 diastereomeric ratio) and high enantioselectivity (up to 91 % enantiomeric excess).     

Organocatalytic Asymmetric 1,6‐Addition/1,4‐Addition Sequence to 2,4‐Dienals for the Synthesis of Chiral Chromans

A novel asymmetric organocatalytic 1,6‐addition/1,4‐addition sequence to 2,4‐dienals is described. Based on a 1,6‐Friedel–Crafts/1,4‐oxa‐Michael cascade, the organocatalyst directs the reaction of hydroxyarenes with a vinylogous iminium‐ion intermediate to give only one out of four possible regioisomers, thus providing optically active chromans in high yields and 94–99 % ee. Furthermore, several transformations are presented, including the formation of an optically active macrocyclic lactam. Finally, the mechanism for the novel reaction is discussed based on computational studies.     

Enantioselective Organocatalytic Conjugate Addition of Aldehydes to Vinyl Sulfones and Vinyl Phosphonates as Challenging Michael Acceptors

Chiral framework : Chiral amines with pyrrolidine frameworks catalyze the enantioselective conjugate addition of a wide range of aldehydes to various vinyl sulfones and vinyl phosphonates in high yields and with enantioselectivities up to >99 % ee (see scheme). The high versatility of the Michael adducts is exemplified by various functionalizations with conservation of the optical purity.

     

Efficacy of Selenourea Organocatalysts in Asymmetric Michael Reactions under Standard and Solvent-Free Conditions

By varying the steric and electronic surroundings of the hydrogen-bonding motif, the novel chiral Cinchona-alkaloid based selenoureas were developed. Acting as bifunctional catalysts, they were applied in the Michael reactions of dithiomalonate and nitrostyrene providing chiral adducts with up to 96% ee. The asymmetric Michael–-hemiacetalization reaction of benzylidene pyruvate and dimedone, performed with the assistance of 5 mol% of selenoureas, furnished the product with up to 93% ee and excellent yields. The effectiveness of the new hydrogen-bond donors was also proved in solvent-free reactions under ball mill conditions, supporting the sustainability of the devised catalytic protocol.