MCM-41 Anchored Cinchona Alkaloid for Catalytic Asymmetric Dihydroxylation of Olefins: A Clean Protocol for Chiral Diols Using Molecular Oxygen

MCM-41 anchored 1,4-bis(9-O-quininyl)phthalazine (MCM-(QN)₂PHAL)-OsO₄, is prepared for the first time and used in the heterogeneous asymmetric dihydroxylation of olefins to afford diols with good to excellent enantiomeric excesses in the presence of N-methylmorpholine N-oxide, K₃Fe(CN)₆ or molecular oxygen as cooxidants.     

N-烯丙基酰胺的不对称双羟化反应

用1∶1的叔丁醇和水作溶剂,在0℃条件下,不同酰基取代的N-烯丙基酰胺在Sharp less催化剂作用下发生不对称双羟化反应,生成手性二醇的产率高达89%,其中N-烯丙基苯甲酰胺获得了50%的对映选择性。     

利用Sharpless不对称双羟基化反应制备光学活性的偶姻类化合物

以相应的酮为起始原料,通过烯醇硅醚的中间体,利用Sharpless不对称双羟基化反应制备了5个光学活性的偶姻化合物。4-庚酮、5-壬酮、2,6-二甲基-4-庚酮、5-甲基-3-己酮和4-苯基-2-丁酮在不同碱的作用下与三甲基氯硅烷或三甲基碘硅烷反应得到动力学控制或热力学稳定的烯醇硅醚后,再进行Sharpless不对称双羟基化反应,除5-甲基-3-己酮的烯醇硅醚外,其他烯醇硅醚用AD-mix-α氧化得到S构型的偶姻产物,对映体过量值(ee值)在62%以上,用AD-mix-β氧化得到R构型的偶姻产物,ee值在75%以上。5-甲基-3-己酮的烯醇硅醚分别用AD-mix-α和AD-mix-β氧化都得到R构型的2-羟基-5-甲基-3-己酮,前者ee值只有16%,后者ee值为76%;用D-果糖和L-果糖衍生的史一安催化剂和过硫酸氢钾氧化,则分别得到R构型和S构型产物,ee值分别为75%和73%。     

Polymer Enzyme Conjugates as Chiral Ligands for Sharpless Dihydroxylation of Alkenes in Organic Solvents

Conjugates of enzymes and poly(2‐methyloxazoline) were used as organosoluble amphiphilic polymer nanocontainers for dissolving osmate, thereby converting the enzymes into organosoluble artificial metalloenzymes. These were shown to catalyze the dihydroxylation of different alkenes with high enantioselectivity. The highest selectivities, found for osmate complexed with laccase polymer–enzyme conjugates (PECs), even exceed those of classical Sharpless catalysts.     

Silica Gel‐Supported Cinchona Alkaloid‐OsO4 Complex for Catalytic Heterogeneous Asymmetric Dihydroxylation of Olefins by H2O2 using a Titanium Silicalite‐Based Coupled Catalytic System

A triple catalytic system designed for asymmetric dihydroxylation of olefins, composed of NMM and two divergent heterogeneous catalysts, titanium silicalite and silica gel‐supported 1,4‐bis(9‐O‐dihydroquinidinyl)phthalazine [SGS‐(DHQD)₂PHAL)]‐OsO₄ complex relays the transport of two electrons from olefin to H₂O₂ used as a terminal oxidant to provide chiral diols with good yields and high enantiomeric excesses in a single pot.     

Towards Heterogeneous and Green Versions of Os Dihydroxylation Catalysis

Os-catalyzed dihydroxylation will find more widespread application if truly heterogeneous catalysts are available which use O₂ or H₂O₂ as terminal oxidants. This paper discusses and critically evaluates the concepts by which Os can be anchored on solid supports. New methods are also available for reoxidation of hexavalent to octavalent Os.     

不对称合成技术在昆虫性信息素合成中的研究进展

不对称合成技术是当前有机化学研究的热点与前沿领域,在药物以及天然产物的全合成中发挥重要作用。本文以＂代＂进行分类,就不对称合成技术在昆虫性信息素合成中的应用进行了归纳和总结,重点介绍了Sharpless环氧化等反应在性信息素不对称合成中的应用,并对今后昆虫性信息素的不对称合成研究动向进行了展望。     

多氧取代环己基甲醇苯甲酸酯的合成及其表征

以莽草酸为原料,经酯化、丙酮叉保护顺式邻二羟基、叔丁基二甲基硅烷保护羟基、还原、羟基酯化、最后双羟基化反应,得到多氧取代环己基甲醇苯甲酸酯(1),总产率为84.1%,其结构经IR、1H NMR和HR MS确证。对双羟基化反应的条件进行了探索,优化条件为:反应时间为15h,溶剂为THF∶H2O=1∶1(V∶V),配料比为n[(3R,4R,5R)-5-叔丁基二甲基硅氧基-3,4-(丙酮叉二氧)-环己基-1-烯烃-1-甲醇苯甲酸酯(5)]∶n(N-甲基吗啉氮氧化物)∶n(OsO4)∶n(手性配体)=100∶150∶0.5∶1,产率为90.6%,e.e.值为75.1%。     

Mannich reaction catalyzed by carboxyl-functionalized ionic liquid in aqueous media

Three-component Mannich reactions of aromatic aldehydes, anilines and acetophenone were efficiently catalyzed by a recyclable carboxyl-functionalized ionic liquid ([cmmim][BF₄]) in aqueous [bmim][BF₄] under mild conditions. Twelve β-aminoketones were successfully synthesized in high yields and the catalyst can be recycled at least 6 times without significant loss of activity.     

经不对称氨羟基化反应合成多西紫杉醇及其衍生物的新方法研究

首次用取代肉桂酸酯和叔丁氧基碳酰胺为原料,经改进的Sharphless不对称氨羟基化反应一步得到了多西紫杉醇及其衍生物的侧链,并最终得到了多西紫杉醇和新型抗癌化合物3,4-亚甲二氧基取代多西紫杉醇,该方法是目前合成多西紫杉醇及其衍生物的最简化和较高收率的路线。研究发现Sharphless不对称氨羟基化反应中手性配体、催化剂的用量和比例对原料的转化率、产物的产率等都有影响,当催化剂K2OsO2(OH)4、手性配体(DHQ)2PHAL的摩尔分数分别为原料的4％和5％时更倾向于生成多西紫杉醇衍生物侧链。所有新化合物及其结构均经过^1HNMR、^13CNMR、IR、MS、旋光度和元素分析等给予确证。3,4-OCH2O取代多西紫杉醇的初步药理活性显示具有较好的抗癌活性。