147384-01-8Relevant articles and documents
Topology-Based Functionalization of Robust Chiral Zr-Based Metal-Organic Frameworks for Catalytic Enantioselective Hydrogenation
Jiang, Hong,Zhang, Wenqiang,Kang, Xing,Cao, Ziping,Chen, Xu,Liu, Yan,Cui, Yong
supporting information, p. 9642 - 9652 (2020/07/02)
The design and development of robust and porous supported catalysts with high activity and selectivity is extremely significant but very challenging for eco-friendly synthesis of fine chemicals and pharmaceuticals. We report here the design and synthesis of highly stable chiral Zr(IV)-based MOFs with different topologies to support Ir complexes and demonstrate their network structures-dependent asymmetric catalytic performance. Guided by the modulated synthesis and isoreticular expansion strategy, five chiral Zr-MOFs with a flu or ith topology are constructed from enantiopure 1,1′-biphenol-derived tetracarboxylate linkers and Zr6, Zr9, or Zr12 clusters. The obtained MOFs all show high chemical stability in boiling water, strongly acidic, and weakly basic aqueous solutions. The two flu MOFs featuring the dihydroxyl groups of biphenol in open and large cages, after sequential postsynthetic modification with P(NMe2)3 and [Ir(COD)Cl]2, can be highly efficient and recyclable heterogeneous catalysts for hydrogenation of α-dehydroamino acid esters with up to 98% ee, whereas the three ith MOFs featuring the dihydroxyl groups in small cages cannot be installed with P(NMe2)3 to support the Ir complex. Incorporation of Ir-phosphorus catalysts into Zr-MOFs leads to great enhancement of their chemical stability, durability, and even stereoselectivity. This work therefore not only advances Zr-MOFs as stable supports for labile metal catalysts for heterogeneous asymmetric catalysis but also provides a new insight into how highly active chiral centers can result due to the framework topology.
Controlled Exchange of Achiral Linkers with Chiral Linkers in Zr-Based UiO-68 Metal-Organic Framework
Tan, Chunxia,Han, Xing,Li, Zijian,Liu, Yan,Cui, Yong
supporting information, p. 16229 - 16236 (2018/11/27)
The development of highly robust heterogeneous catalysts for broad asymmetric reactions has always been a subject of interest, but it remains a synthetic challenge. Here we demonstrated that highly stable metal-organic frameworks (MOFs) with potentially acid-labile chiral catalysts can be synthesized via postsynthetic exchange. Through a one- or two-step ligand exchange, a series of asymmetric metallosalen catalysts with the same or different metal centers are incorporated into a Zr-based UiO-68 MOF to form single- and mixed-M(salen) linker crystals, which cannot be accomplished by direct solvothermal synthesis. The resulting MOFs have been characterized by a variety of techniques including single-crystal X-ray diffraction, N2 sorption, CD, and SEM/TEM-EDS mapping. The single-M(salen) linker MOFs are active and efficient catalysts for asymmetric cyanosilylation of aldehydes, ring-opening of epoxides, oxidative kinetic resolution of secondary alcohols, and aminolysis of stilbene oxide, and the mixed-M(salen) linker variants are active for sequential asymmetric alkene epoxidation/epoxide ring-opening reactions. The chiral MOF catalysts are highly enantioselective and completely heterogeneous and recyclable, making them attractive catalysts for eco-friendly synthesis of fine chemicals. This work not only advances UiO-type MOFs as a new platform for heterogeneous asymmetric catalysis in a variety of syntheses but also provides an attractive strategy for designing robust and versatile heterogeneous catalysts.
The first porphyrin-salen based chiral metal-organic framework for asymmetric cyanosilylation of aldehydes
Li, Jiawei,Ren, Yanwei,Qi, Chaorong,Jiang, Huanfeng
supporting information, p. 8223 - 8226 (2017/07/24)
The first porphyrin-salen based chiral metal-organic framework (ps-CMOF) constructed by judiciously incorporating metalloporphyrin and metallosalen struts into one MOF structure is reported, which can serve as an effective heterogeneous catalyst for the a
Multivariate Metal-Organic Frameworks as Multifunctional Heterogeneous Asymmetric Catalysts for Sequential Reactions
Xia, Qingchun,Li, Zijian,Tan, Chunxia,Liu, Yan,Gong, Wei,Cui, Yong
supporting information, p. 8259 - 8266 (2017/06/28)
The search for versatile heterogeneous catalysts with multiple active sites for broad asymmetric transformations has long been of great interest, but it remains a formidable synthetic challenge. Here we demonstrate that multivariate metal-organic frameworks (MTV-MOFs) can be used as an excellent platform to engineer heterogeneous catalysts featuring multiple and cooperative active sites. An isostructural series of 2-fold interpenetrated MTV-MOFs that contain up to three different chiral metallosalen catalysts was constructed and used as efficient and recyclable heterogeneous catalysts for a variety of asymmetric sequential alkene epoxidation/epoxide ring-opening reactions. Interpenetration of the frameworks brings metallosalen units adjacent to each other, allowing cooperative activation, which results in improved efficiency and enantioselectivity over the sum of the individual parts. The fact that manipulation of molecular catalysts in MTV-MOFs can control the activities and selectivities would facilitate the design of novel multifunctional materials for enantioselective processes.
An orthogonal biocatalytic approach for the safe generation and use of HCN in a multistep continuous preparation of chiral O-acetylcyanohydrins
Brahma, Aischarya,Musio, Biagia,Ismayilova, Uliviya,Nikbin, Nikzad,Kamptmann, Sonja B.,Siegert, Petra,Jeromin, Günter E.,Ley, Steven V.,Pohl, Martina
, p. 262 - 266 (2016/01/20)
An enantioselective preparation of O-acetylcyanohydrins has been accomplished by a three-step telescoped continuous process. The modular components enabled an accurate control of two sequential biotransformations, safe handling of an in situ generated hazardous gas, and in-line stabilization of products. This method proved to be advantageous over the batch protocols in terms of reaction time (40 min vs 345 min) and ease of operation, opening up access to reactions which have often been neglected due to safety concerns.
Dual Lewis Acid/Lewis Base Catalyzed Acylcyanation of Aldehydes: A Mechanistic Study
Laurell Nash, Anna,Hertzberg, Robin,Wen, Ye-Qian,Dahlgren, Bj?rn,Brinck, Tore,Moberg, Christina
, p. 3821 - 3829 (2016/03/08)
A mechanistic investigation, which included a Hammett correlation analysis, evaluation of the effect of variation of catalyst composition, and low-temperature NMR spectroscopy studies, of the Lewis acid-Lewis base catalyzed addition of acetyl cyanide to prochiral aldehydes provides support for a reaction route that involves Lewis base activation of the acyl cyanide with formation of a potent acylating agent and cyanide ion. The cyanide ion adds to the carbonyl group of the Lewis acid activated aldehyde. O-Acylation by the acylated Lewis base to form the final cyanohydrin ester occurs prior to decomplexation from titanium. For less reactive aldehydes, the addition of cyanide is the rate-determining step, whereas, for more reactive, electron-deficient aldehydes, cyanide addition is rapid and reversible and is followed by rate-limiting acylation. The resting state of the catalyst lies outside the catalytic cycle and is believed to be a monomeric titanium complex with two alcoholate ligands, which only slowly converts into the product.
Fast microwave-assisted resolution of (±)-cyanohydrins promoted by lipase from Candida antarctica
Ribeiro, Sandra S.,Ferreira, Irlon M.,Lima, Jo?o P. F.,De Sousa, Bruno A.,Carmona, Rafaela C.,Santos, Alcindo A. Dos,Porto, André L. M.
, p. 1344 - 1350 (2015/07/15)
Enzymatic kinetic resolution (EKR) of (±)-cyanohydrins was performed by using immobilized lipase from Candida antarctica (CALB) under conventional ordinary conditions (orbital shaking) and under microwave radiation (MW). The use of microwave radiation contributed very expressively on the reduction of the reaction time from 24 to 2 h. Most importantly, high selectivity (up to 92percent eep) as well as conversion was achieved under MW radiation (50-56percent).
Direct and Post-Synthesis Incorporation of Chiral Metallosalen Catalysts into Metal-Organic Frameworks for Asymmetric Organic Transformations
Xi, Weiqin,Liu, Yan,Xia, Qingchun,Li, Zijian,Cui, Yong
, p. 12581 - 12585 (2015/09/01)
Two chiral porous metal-organic frameworks (MOFs) were constructed from [VO(salen)]-derived dicarboxylate and dipyridine bridging ligands. After oxidation of VIV to VV, they were found to be highly effective, recyclable, and reusable
Chemoenzymatic flow cascade for the synthesis of protected mandelonitrile derivatives
Delville, Marille M. E.,Koch, Kaspar,Van Hest, Jan C. M.,Rutjes, Floris P. J. T.
supporting information, p. 1634 - 1638 (2015/03/05)
A chemoenzymatic two-step cascade process, with both steps having incompatible reaction conditions, was successfully performed in continuous flow. The chemoenzymatic aqueous formation of cyanohydrins was integrated with a subsequent organic phase protection step in a single flow process utilising a membrane-based phase separation module. The wider applicability of our setup was demonstrated with the synthesis of nine protected cyanohydrin derivatives, all obtained in good yields and high to excellent enantioselectivity.
A simple separation method for (S)-hydroxynitrile lyase from cassava and its application in asymmetric cyanohydrination
Zheng, Zubiao,Zi, Yan,Li, Zhongzhou,Zou, Xinzhuo
, p. 434 - 439 (2013/06/27)
Using an acetone precipitation method, crude (S)-hydroxynitrile lyase [(S)-MeHNL] was separated from Munihot esculenta (cassava) leaves, and used directly as biocatalyst to catalyze asymmetric cyanohydrination and produce cyanohydrins with enantiomeric purities (≥90% ee) significantly greater than those previously reported. The use of a water/i-Pr2O system with an enzyme, NaCN, and appropriate amounts of acetic acid is crucial in improving the stereoselectivity of cyanohydrin formation by minimizing the non-enzymatic reaction and the racemization of the chiral products. The proposed isolation method for crude (S)-MeHNL has a high value because of its simplicity, and low cost as well as the high activity of the crude (S)-MeHNL.