描述了钒氨基三酚盐催化邻位二醇的好氧氧化CC键裂解。我们的结果表明,在空气或氧气气氛下,可以使用多种乙二醇(环状或直链,具有芳族或脂肪族取代基)在不同溶剂中进行C-C键裂解,从而提供具有高化学选择性的相应羰基衍生物。可以在低至10 ppm的催化剂下达到TON达到81,000和TOF达到4150 h -1的情况下进行反应。还提出了通过密度泛函理论计算合理化的反应机理。
Diols obtained via chemo and regioselective ring opening of epoxy alcohols: a straightforward synthesis of 2S,3S-Octandiol
摘要:
Epoxy alcohols are regio and chemoselectively opened to the corresponding iodohydrins and then reduced in situ to diols; the application of the described procedure leads to a short asymmetric synthesis of a well known pheromone. Also homoallylic (E and Z) epoxy alcohols and its benzylated derivatives shows high preference for regioselective opening affording the corresponding 1,3 diol.
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
Mechanistically Driven Development of an Iron Catalyst for Selective <i>Syn</i>-Dihydroxylation of Alkenes with Aqueous Hydrogen Peroxide
作者:Margarida Borrell、Miquel Costas
DOI:10.1021/jacs.7b07909
日期:2017.9.13
to be resolved in the design of iron catalysts for olefin syn-dihydroxylation with potential utility in organic synthesis. Toward this end, in this work a novel catalyst bearing a sterically encumbered tetradentate ligand based in the tpa (tpa = tris(2-methylpyridyl)amine) scaffold, [FeII(CF3SO3)2(5-tips3tpa)], 1 has been designed. The steric demand of the ligand was envisioned as a key element to support
catalysts for efficient and selective alkene oxidation (epoxidation and cis‐dihydroxylation) employing hydrogenperoxide as oxidant. Complex [Fe(II)(Me,Me,HPyTACN)(CF3SO3)2] (7), was identified as the most efficient and selective cis‐dihydroxylation catalyst among the family. The high activity of 7 allows the oxidation of alkenes to proceed rapidly (30 min) at room temperature and underconditions where the
通式为[Fe(II)(R,Y,X PyTACN)(CF 3 SO 3)2 ]的铁络合物家族,其中R,Y,X PyTACN = 1‐ [2′‐(4‐Y‐6 -[X-吡啶基)甲基] -4,7-二烷基-1,4,7-三氮杂环壬烷,X和Y分别表示吡啶的4和6位上的基团,R表示在N-处的烷基取代基三氮杂双环壬烷环的4和N-7被证明是使用过氧化氢作为氧化剂进行有效且选择性的烯烃氧化(环氧化和顺式-二羟基化)的催化剂。络合物[Fe(II)(Me,Me,H PyTACN)(CF 3 SO 3)2 ](7)被认为是该家族中最有效和选择性最强的顺式-二羟基化催化剂。7的高活性使烯烃的氧化在室温下以及在不大量使用烯烃而仅是限制性试剂的条件下迅速进行(30分钟)。在3%(摩尔)的存在下7,2当量。H 2 O 2作为氧化剂,当量为15当量。在乙腈溶液中,水被烯烃顺式-二羟基化,其收率可能对于合成目的是令人感兴趣的。竞
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
Enantioselective microbial hydrolysis of dissymmetrical cyclic carbonates with disubstitution
Enantioselective microbial hydrolysis of C1 and C2 dissymmetrical cyclic carbonates with disubstitution (methyl and another groups) has been developed. Pseudomonas diminuta (FU0090), a bacterium, efficiently catalyzes the hydrolysis of five-membered cyclic carbonates. While the trans-substrates are hydrolyzed with low enantioselectivities and/or reactivities, the microbe hydrolyzes the cis-substrates