【作者】 刘昆；

【导师】 马军安；

【作者基本信息】 天津大学 ， 有机化学， 2008， 硕士

【摘要】 手性硫脲是有机小分子催化剂的一个重要研究方向。硫脲分子容易连接其他官能团而得到双功能的催化剂:催化过程中不仅仅有氢键的Lewis酸性活化亲电性的反应底物,还可以通过另一官能团活化亲核性反应物,从而可以表现出非常高的催化活性和立体选择性。Michael加成反应是有机化学领域应用广泛的非常重要的碳-碳键形成反应。近年来,不对称Michael加成反应的研究得到了极大的发展。本文中,设计了一大类手性硫脲小分子催化剂,在不对称Michael加成反应中表现出良好的效果。由廉价的糖化合物经过简单的转化,高收率的合成手性伯胺基硫脲。尝试了不同的酮对反式硝基烯烃的Michael加成,测试了催化剂构型匹配、筛选了反应中的溶剂、反应温度、添加剂、反应物的当量比等等的影响因素。探索出最佳反应条件,高收率的分离出了高对映选择性的加成产物。1, 2-环己二胺骨架的硫脲2a适用于以芳香酮为Michael供体的反应,21种芳香酮的加成产物能获得高达98%的ee值和大于99%的收率。1, 2-二苯基乙烷-1, 2-二胺骨架的硫脲4a能促进环状脂肪酮高对映选择性的加成E-硝基烯烃,14种加成产物都获得了非常好的对映选择性和非对映选择性。所有新化合物都通过红外光谱、核磁共振氟谱、核磁共振氢谱、核磁共振碳谱、质谱和元素分析确证了结构。催化剂4a通过X-衍射得到了晶体结构,为我们揭示了反应的高选择性的原因,以此为依据,提出了反应的过渡态。更多还原

【Abstract】 Organocatalysis has become an important protocol in the field of asymmetric catalysis. Among these organocatlysts, chiral thiourea is a outstanding bifunctional catalyst for many reactions.Michael addition is one of most important carbon-carbon bond-forming reactions in organic synthesis. Over the past decades highly enantioselective Michael addition attracts lots of attention. In the context, asymmetric addition of ketone to trans-nitroolefin is involved in synthesis of many natural products. Chiral thiourea bearing primary amine group is ideal catalyst which can dually activate both ketone and olefin.A series of chiral primary amine-thiourea were synthesized from commercially, non-toxic carbohydrates through three-easy handle-step. These catalysts were screened in addition of ketone to trans-nitroolefin. Different parameters were tested to disclose the appropriate catalyst loading, solvent, temperature, additive et al. Thiourea based on 1, 2-cyclohexanediamine promoted the aryl ketones addition to trans -nitroolefin with up to 99% yield and 98% ee. Thiourea prepared from 1, 2-diphenylethane -1, 2-diamine gave excellent results in catalyzing cyclic ketones Michael addition nitroolefins.Under the optimized condition, 35 adducts were separated and all new products were characterized by NMR, IR, MS and HRMS. The thiourea 4a was applied to X-ray analysis. The presumed transition state was rationalized by the crystalline structure of the thiourea.更多还原