【作者】 吴传隆；

【导师】 马学兵；

【作者基本信息】 西南大学 ， 有机化学， 2008， 硕士

【摘要】 手性分子在科学和技术上扮演着重要的角色。而不对称催化在获得手性化合物中占有很重要的地位,最具有吸引力。因为它会以少量的手性配体生产出大量的具有光学活性的产品,符合原子经济的环境友好过程。近三十年来,不对称催化已经成为了化学研究的前沿领域。手性的具有C₂型轴对称的双噁唑啉类化合物由于其独特的立体结构和电子效应,在不对称催化反应中已经成为了一类优良的手性配体。本文分别以手性的联二萘酚、氯乙酸和L-丝氨酸甲酯盐酸盐为主要原料,经过一系列的化学反应,合成了一类新型的以手性联二萘酚为骨架具有C₂型轴对称双噁唑啉类化合物42和43,并用IR、¹H NMR、¹³C NMR等表征手段对催化剂的组成和结构进行了表征,并将该类配体应用于催化二乙基锌对苯甲醛的不对称加成反应中。在0℃的条件下,甲苯/正己烷（v/v=1:1）作溶剂,反应24 h,（R,S,S）-43c在催化二乙基锌对苯甲醛的不对称加成反应,获得91%的产率和86%的对映选择性。文献报道手性双噁唑啉酯类化合物在催化二乙基锌对苯甲醛的不对称加成反应时,没有对映选择性,但本文以联二萘酚衍生的双手性中心的双噁唑啉酯类化合物（R,S,S）-42a和（S,S,S）-42b却分别获得了44%和40%的对映选择性。实验表明联二萘酚的绝对构型以及羟基碳上所连的基团大小对催化二乙基锌与苯甲醛的不对称加成反应的对映选择性和催化活性有重要影响,并存在骨架结构与催化中心的协同效应。结合文献报道和本文实验数据,提出了催化加成反应中协同效应的可能反应机理。更多还原

【Abstract】 Chiral molecules play a very important role both in science and technology. Asymmetric catalysis is the most important and attractive way for the preparation of chiral compounds, because a little mount of chiral catalyst can get a great deal of chiral compounds, and the catalytic proccess is atomic economic and friendly to the environment. In recent thirty years, asymmetric catalysis has been advanced frontier in chemistry.In asymmetric catalysis, chiral C₂-bisoxazoline compounds were proved to be a type of effective catalysts owing to their particular steric structure and electronic effect. In this paper, the novel type of C₂-symmetic bisoxazoline ligands 42 and 43 with chiral binaphthol backbone had been designed and prepared from chiral 1,1 ’-Bi-2-naphthol, chloroacetic acid and easily available L-serine methyl ester hydrochloride. The ligands had been determined by IR、¹H NMR、¹³C NMR and applied in the alkylation of diethylzinc to benzaldehyde. At 0℃for 24 h in toluene/hexane （v/v=1:1）, the 91% yield and up to 86% e.e were obatained for the catalytic addition of diethylzinc to benzaldehyde by using the ligand （R, S,S）-43C.Based on literatures, the C₂-symmetric bis（oxazoline）-ester resulted in no enantioselectivity. However, the 44 % e.e and 40 % e.e were obtained by C₂-symmetric bis（oxazoline）-ester ligands （R,S,S） -42a and （S,S,S）-42b derived from binaphthol backbone for the asymmetric alkylation of diethylzinc to benzaldehyde. It was shown that the configuration of chiral binaphthol and the bulkiness of substituted group at hydroxyl position play an important role on the catalytic activities and enantioselectivities, and there was the cooperative effect between chiral binaphthol backbone and active catalytic site. Based on the literatures and experimental data, the possible mechanism was put forth to elucidate the cooperative effect.更多还原