关键词： 亚胺   串联反应   立体选择性   β-氨基酮   硫叶立德   氮杂环丙烷  

摘要： 该论文主要对亚胺的某些立体选择性反应进行了研究。研究人员开展了亚胺参加的Michael-Imino Aldol串联反应的研究。首先研究人员用硫负离子来引发串联反应,通过硫负离子对α,β-不饱和酮的共轭加成而后用亚胺捕获生成的中间体,顺利地得到了预期的串联反应产物。其次,研究人员以二乙基锌来引发串联反应,发现HMPA对反应的选择性同样产生显著的影响,并通过在反应体系中加入4当量的HMPA,高立体选择性地得到了β-氨基酮类化合物。在高非对映选择性的基础上,研究人员以文献报道的BINOL衍生的单磷化合物为配体,高对映选择性地实现了Michael-Imino Aldol串联反应,主产物的ee值最高可在94.9﹪。此外,作为硕士工作的延续,研究人员经由硫叶立德途径的氨杂环丙烷化做了进一步的研究。

关键词： 硫叶立德   一锅法   环丙烷化   β-不饱和羰基化合物   羧酸酯   国家重点实验室   元素有机化学   对映异构体过量值   南开大学   全反式  

关键词： OPTICALLY-ACTIVE EPOXIDES   TERTIARY ALCOHOLS   SULFONIUM YLIDES   NUCLEOPHILIC-ADDITION   GRIGNARD-REAGENTS   CERIUM CHLORIDE   SULFIDES   CYCLOPROPANATION   SUBSTITUTION   GENERATION  

摘要： A range of 1,3-oxathianes based on camphorsulfonic acid have been prepared and tested in the catalytic asymmetric epoxidation of carbonyl compounds. It was found that the 1,3-oxathiane derived from acetaldehyde 5b gave the highest yield and enantioselectivity in the epoxidation process. The enantioselectivity was independent of the solvent and metal catalyst used (although yields were dependent on both). The optimum conditions were applied to a range of aldehydes, and good enantioselectivities and diastereoselectivities were observed. The origin of the enantioselectivity was probed, and in particular the role of the oxygen of the 1,3-oxathiane was investigated. Thus, the sulfur and carbon analogues of the camphorsulfonic acid based 1,3-oxathiane (derived from formaldehyde) were prepared (i.e., 1,3-dithiane and thiane analogues). With this series of analogues the steric effects are minimized so that the electronic effects can be investigated. The series of compounds was reacted in the catalytic cycle with benzaldehyde and gave stilbene oxides with 44% ee (sulfur analogue), 41% ee (1,3-oxathiane), and 20% ee (carbon analogue). Thus, it was concluded that the oxygen of the 1,3-oxathiane exerted a significant electronic effect in controlling the face selectivity of the ylide reactions. This electronic effect was a result of combined anomeric (higher with the sulfur analogue, not present with the carbon analogue) and Cieplak effects. A strong anomeric effect was observed in the X-ray structures of one of the 1,3-oxathianes, and an even greater one was observed in the corresponding sulfoxide (this was used as an electronic analogue of the ylide). The face selectivity of the ylide was believed to be complete in reactions with 5b. The minor enantiomer resulted from reaction of the miner conformer of the ylide, reacting again with high face selectivity. This was proven by using a more substituted diazo compound, which was expected to give much less of the minor conformer. In

关键词： 硫苄基   硒苄基   叶立德   硫叶立德   硒叶立德  

关键词： 手性胶束   硫叶立德   醛   酮   不对称环氧化  

关键词： DIAZOACETATE   PROTECTION   ALDEHYDES   IMINES   AMINES  

摘要： Proposes a catalytic cycle for aziridination. Total yield of trans and cis isomers; Preparation of aziridines from imines and phenyldiazomethane; Derivation of chiral sulfides.

关键词： 三烷基硼烷   巴豆烷酸乙酯   化学反应  

摘要： 三烷基硼烷能与4-(二甲基硫叶立德)巴豆酸乙酯反应,给出(E/Z)-β,γ-不饱和酯(E:Z≈58:42),条件温和,产率高.该反应是一条使烷基延长四个碳原子得到β,γ-不饱和酯的新路线。

关键词： 氧硫叶立德   羰基化合物   相转移催化  

摘要： 本文报导在苯和氢氧化钠水溶液组成的两相体系中,在相转移催化剂TBAI的作用下,碘化三甲基氧锍鎓盐分别与△^(5、16)——3-羟基-孕甾-20-酮反应,生成△~5-16、17-环丙基-3-羟基-孕甾-20-酮;与香芹酮反应生成1-甲基-4-异丙基双环-[4、1、0]-庚酮-2;与苯甲醛的反应,不加TBAI,反应也顺利进行,仍然得到与加TBAI相同的结果,产物为2-苯基环氧乙烷。从而认为,在这反应中,碘化三甲基氧锍鎓盐本身,起着相转移催化剂的作用。