Highly Enantioselective Iron-Catalyzed <i>cis</i>
-Dihydroxylation of Alkenes with Hydrogen Peroxide Oxidant via an Fe<sup>III</sup>
-OOH Reactive Intermediate
作者:Chao Zang、Yungen Liu、Zhen-Jiang Xu、Chun-Wai Tse、Xiangguo Guan、Jinhu Wei、Jie-Sheng Huang、Chi-Ming Che
DOI:10.1002/anie.201603410
日期:2016.8.22
catalysts for highly enantioselective asymmetric cis‐dihydroxylation (AD) of alkenes with broad substrate scope remains a challenge. By employing [FeII(L)(OTf)2] (L=N,N′‐dimethyl‐N,N′‐bis(2‐methyl‐8‐quinolyl)‐cyclohexane‐1,2‐diamine) as a catalyst, cis‐diols in up to 99.8 % ee with 85 % isolated yield have been achieved in AD of alkenes with H2O2 as an oxidant and alkenes in a limiting amount. This “[FeII(L)(OTf)2]+H2O2”
开发具有良好底物范围的烯烃的高对映选择性不对称顺二羟基化(AD)的环境友好型催化剂仍然是一个挑战。通过使用[Fe II(L)(OTf)2 ](L = N,N'-二甲基-N,N'-双(2-甲基-8-喹啉基)-环己烷-1,2-二胺)作为催化剂,在以H 2 O 2为氧化剂的烯烃和数量有限的烯烃的AD中,已实现了高达99.8%ee的顺式二醇和85%的分离产率。该“ [Fe II(L)(OTf)2 ] + H 2 O 2”方法适用于(E)-烯烃和末端烯烃(24个实例,ee大于80%,最大1 g)。机理研究包括18种O-标记,UV / Vis,EPR,ESI-MS分析和DFT计算,为手性Fe III- OOH活性物种参与两个C-O键的对映选择性形成提供了证据。
Enantioselective Bio-Hydrolysis of Various Racemic and <i>meso</i>
Aromatic Epoxides Using the Recombinant Epoxide Hydrolase Kau2
substrate concentrations (up to 75 g/L) to be reached. Even extremely sterically demanding epoxides such as cis‐ and trans‐stilbene oxides were transformed on a reasonable time scale. All reactions were successfully conducted on a 1 g preparative scale, generating diol‐ and epoxide‐based chiral synthons with very high enantiomeric excesses and isolated yields close to the theoretical maximum. Thus we
已用十种不同的外消旋和内消旋体测试了在大肠杆菌RE3中过表达的环氧水解酶Kau2α,β-二取代的芳族环氧化物。一些经过测试的底物是双功能的,其中大多数是合成化学应用中非常有用的构建基块。作为一种普遍趋势,Kau2被证明是一种对映体选择性极强的生物催化剂,除了几乎对映体纯净的形式外,还获得了生物转化的二醇产物和剩余的环氧化物(有两个例外)。此外,反应时间通常很短(大约1小时,使用二氧化二苯乙烯时除外),并且有机共溶剂的使用被很好地耐受,从而可以达到很高的底物浓度(最高75 g / L)。 。甚至对空间要求极高的环氧化物,例如顺式和反式sti氧化物在合理的时间范围内转化。所有反应均以1 g制备规模成功进行,生成了对映体过量非常高且分离出的收率接近理论最大值的基于二醇和环氧化物的手性合成子。因此,我们在这里证明了表达Kau2环氧水解酶作为高度对映选择性的生物催化剂的冻干大肠杆菌细胞的有用性和多功