【作者】 丁寒锋；

【导师】 马成； 王彦广；

【作者基本信息】 浙江大学 ， 有机化学， 2008， 博士

【摘要】 碳-碳和碳-杂原子键的形成反应是有机合成研究的核心问题。利用亲核试剂与活泼π体系加成而得的两性离子作为反应中间体参与的有机反应已成为目前该领域研究的热点。本论文在综述了近年来以吡啶、叔胺、叔膦及氮杂环卡宾为亲核试剂形成的两性离子在碳-碳和碳-杂原子键形成反应中取得一系列进展的基础上,研究、发展了N-甲基咪唑参与的碳-碳和碳-氮键的形成反应及噻唑卡宾参与的三组分串联反应,主要内容如下:1.我们用烯酮来捕捉N-甲基咪唑与活泼炔DMAD形成的两性离子。研究中,我们首先发现了一个新的N-甲基咪唑催化的DMAD与原位产生的单取代烯酮的二组分反应,在温和的条件下以中等收率合成了(Z)-型和(E)-型的取代亚苄基琥珀酸二甲酯。在同位素标记基础上,我们推测了这个N-甲基咪唑催化的二组分反应可能的机理,并根据此机理设计用一个二取代的烯酮来捕捉N-甲基咪唑和DMAD形成的两性离子。实验结果表明,在形成可能的中间体B以后,由于烯酮取代基的作用,Michael加成被抑制,进而发生一个三组分串联反应,得到吡咯并咪唑衍生物。在此反应中,烯酮体现出不寻常的反应活性,作为“单碳”组分参与了形式上的[4+1]反应,形成五员环。2.我们用活泼炔DMAD捕捉了噻唑卡宾和醛形成的两性离子(Breslow中间体),发现并发展了一个新的噻唑卡宾、醛和DMAD的多组分串联反应,在温和的反应条件下以较好的收率合成了多取代的3-氨基呋喃衍生物。整个反应的历程取决于噻唑卡宾的亲核性,而卡宾前体在有机溶剂中的溶解性对反应也有较大的影响。同时,引入4-甲基噻唑盐作为卡宾前体,使整个反应的原子经济性得到了提高。此外,该反应对醛的适用范围较广,芳香醛、α,β-不饱和醛、甚至一些脂肪醛都能顺利进行反应。3.我们发现了一种新的噻唑卡宾和烯酮形成的两性离子的存在,并用活泼炔成功捕捉,从而发展了一个新的噻唑卡宾或苯并噻唑卡宾、二取代烯酮和活泼炔的三组分串联反应。通过这种方法,我们可以由简单易得的起始原料开始,以高度的原子经济性简便高效的合成呋喃并1,4-硫卓骨架。研究中,我们首次观察到了对烯酮的1,3-加成反应。另外,我们进一步研究了呋喃[2,3-C]并硫卓类化合物与苯炔的Diels-Alder反应,以高收率得到了1,4-硫卓并7-氧杂降冰片烯衍生物,此类结构可能具有潜在的可观的合成价值和生物学价值。更多还原

【Abstract】 Carbon-carbon and carbon-heteroatom bond-forming reactions are central to organic synthesis. Zwitterions resulting from the addition of nucleophiles to activatedπsystems, although known for a long time, have not been recognized adequately by researchers. In this thesis, based on the review aiming at developments of zwitterions in synthesis using pyridine, tertiary amine, phosphine and N-heterocyclic carbenes as nucleophiles, we have described several N-methylimidazole engaged carbon-carbon and carbon-nitrogen bond-forming reactions and thiazole carbene mediated three-component tandem reactions. The details are summarized as following:1. The zwitterion derived from the addition of N-methylimidazole to DMAD was investigated and intercepted by a ketene. In this process, we have discovered a novel N-methylimidazole catalyzed two-component reaction. Dimethyl (Z)- and (E)- succinates can be synthesized in moderate yields under mild conditions. In the meantime, we proposed a mechanism for this catalytic reaction. According to the possible formation of intermediate B, we designed a disubstituted ketene of more function to re-capture the zwitterion. In this process, we have discovered a three-component tandem reaction leading to the formation of 6-vinyl-1,3a-diazapentalene derivatives. The ketene was found act as a one-carbon component in the reaction to form a five-membered ring.2. We captured the zwitterions derived from the addition of thiazole carbene to aldehyde using DMAD, and developed a facile and effective synthesis of highly substituted 3-aminofuran derivatives via a novel multicomponent reaction of thiazole carbenes, aldehydes and DMAD in moderate to good yields. It is ascertained the whole tandem reaction sequence pivots on the nucleophilicity of thiazole carbenes, and the solubility of thiazolium precursors has an enormous effect on the reactions. Moreover, an improved overall economy of the process could be achieved by using 4-methylthiazolium salts as carbene precursors. Furthermore, the reaction seems to be applicable to various aldehydes, besides aromatic aldehydes,α,β-unsaturated aldehydes and some aliphatic aldehydes could also complete the reaction smoothly.3. A novel zwitterion derived from the addition of thiazole carbene to ketene was discovered and captured by an activated alkyne. In this process, we developed a facile and efficient three-component tandem reaction involving thiazole or benzothiazole carbene, disubstituted ketene and activated alkyne. A highly substituted ring system containing furo[2,3-c]thiazepine core can be generated from simple and readily accessible starting materials via this methodology. In this reaction, the first example of 1,3-addition to ketene was observed. Furthermore, the synthetic utilities of these unique polyheterocyclic compounds were demonstrated via their Diels-Alder reactions with benzynes to furnish thiazepine-fused 7-oxanorbornadiene derivatives in excellent yields.更多还原