Ruthenium- and lipase-catalyzed DYKAT of 1,2-diols: an enantioselective synthesis of syn-1,2-diacetates
摘要:
Regio- and stercoselective lipase-catalyzed kinetic resolutions were investigated for some unsymmetrical, secondary/secondary syn-diols. Candida antarctica lipase B-catalyzed transesterifications of a few aryl/alkyl- and alkyl/alkyl 1,2-diols were coupled in one-pot for efficient ruthenium-catalyzed epimerization and intramolecular acyl migration to give a dynamic kinetic asymmetric transformation (DYKAT) affording enantioenriched (ee up to > 99%) syn-diacetates as the main diastereomers (sywanti similar to 2:1 to 10:1). (c) 2006 Elsevier Ltd. All rights reserved.
An Osmium(III)/Osmium(V) Redox Couple Generating Os<sup>V</sup>(O)(OH) Center for <i>cis</i>-1,2-Dihydroxylation of Alkenes with H<sub>2</sub>O<sub>2</sub>: Os Complex with a Nitrogen-Based Tetradentate Ligand
2-dihydroxylation of alkenes catalyzed by osmium(VIII) tetroxide (OsO(4)) is a powerful method. However, OsO(4) is quite toxic due to its highly volatile and sublimable nature. Thus, the development of alternative catalysts for cis-1,2-dihydroxylation of alkenes is highly challenging. Our approach involves the use of a nitrogen-based tetradentate ligand, tris(2-pyridylmethyl)amine (tpa), for an osmium center to
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。
Olefin-Dependent Discrimination between Two Nonheme HOFe<sup>V</sup>O Tautomeric Species in Catalytic H<sub>2</sub>O<sub>2</sub>Epoxidations
作者:Anna Company、Yan Feng、Mireia Güell、Xavi Ribas、Josep M. Luis、Lawrence Que、Miquel Costas
DOI:10.1002/chem.200802597
日期:2009.3.23
water incorporation into products (up to 75 %) is observed in epoxidation reactions with H2O2 by a bioinspired nonheme iron catalyst. A surprising substrate‐dependent incorporation of water is observed, and is proposed to arise from fast equilibrium betweentwo high‐valent HOFeVO isomeric species exhibiting different reactivity.
湿式加氧酶模型:在通过生物启发的非血红素铁催化剂与H 2 O 2进行的环氧化反应中,观察到前所未有的高水平的水混入产品(高达75%)。水的令人惊讶的衬底依赖性掺入观察到的,并提出了两个高价HO之间从快速平衡出现铁V表现出不同的反应性O异构体物种。
A Well-Defined Osmium–Cupin Complex: Hyperstable Artificial Osmium Peroxygenase
catalyze cis-dihydroxylation of several alkenes efficiently. With the low catalyst loading (0.01% mol), up to 9100 turnover number was achieved for the dihydroxylation of 2-methoxy-6-vinyl-naphthalene (50 mM) using an equivalent of H2O2 as oxidant at 70 °C for 12 h. When octene isomers were dihydroxylated in a preparative scale for 5 h (2% mol cat.), the terminal alkene octene isomers was converted to the
来自海栖热袍菌的热稳定 TM1459 铜蛋白超家族蛋白通过采用金属结合混杂的金属取代策略被重新用作锇 (Os) 过氧化酶。这种新型人工金属酶带有由 4-组氨酸基序支持的与价结合的 Os 离子。明确定义的 Os 中心不仅负责催化活性,还负责蛋白质折叠的热力学稳定性,从而产生强大的生物催化剂(Tm ≈ 120 °C)。Os 结合的 TM1459 的光谱分析和原子分辨率 X 射线晶体结构揭示了 Os 中心的两种类型的供体组,具有八面体配位几何。一种包括反式二氧化物、OH 和三聚体-三组氨酸咪唑(O3N3 供体组),而另一种具有四个组氨酸咪唑加上顺式位置的 OH 和水分子(O2N4 供体组)。具有后一种供体组(O2N4 供体组)的 Os 结合 TM1459 被评估为过氧化酶,它能够有效地催化几种烯烃的顺式二羟基化。在低催化剂负载量 (0.01% mol) 下,使用等量的 H2O2 作为氧化剂在 70°C
Assignment of the relative and absolute configurations of acyclic secondary 1,2-diols
作者:Shuhei Higashibayashi、Yoshito Kishi
DOI:10.1016/j.tet.2004.08.101
日期:2004.12
solvent (R,R)- and (S,S)-BMBA-p-Me (2) were found to be significantly different. On the basis of this NMR characteristic, a method has been developed to predict both the relative and absoluteconfigurations of acyclic secondary 1,2-diols.