5350-71-0Relevant academic research and scientific papers
Metal-Organic Framework Anchored with a Lewis Pair as a New Paradigm for Catalysis
Niu, Zheng,Bhagya Gunatilleke, Wilarachchige D.C.,Sun, Qi,Lan, Pui Ching,Perman, Jason,Ma, Jian-Gong,Cheng, Yuchuan,Aguila, Briana,Ma, Shengqian
, p. 2587 - 2599 (2018/12/02)
Lewis pair (LP) chemistry has shown broad applications in the catalysis field. However, one significant challenge has been recognized as the instability for most homogeneous LP catalysts upon recycling, thus inevitably leading to dramatic loss in catalytic activity. Additionally, current heterogeneous LP catalysts suffer from low surface area, which largely limits their catalytic efficiency, thereby restricting their potential applications. In this work, we report the successful introduction of LPs, classical and frustrated, into a metal-organic framework (MOF) that features high surface and ordered pore structure via a stepwise anchoring strategy. Not only can the LP be stabilized by the strong coordination interaction between the LP and MOF, but the resultant MOF-LP also demonstrates excellent catalysis performance with interesting size and steric selectivity. Given the broad applicability of LPs, our work therefore paves a way for advancing MOF-LP as a new paradigm for catalysis. Lewis pairs (LPs), classical and frustrated, are excellent prospects in catalysis, organic syntheses, biology, and material sciences. However, the instability of most LP catalysts leads to a dramatic loss in activities, thereby largely restricting their industrial applications. As robust porous materials, metal-organic frameworks (MOFs) offer a platform to stabilize homogeneous catalysts. Here, we show a strategy that grafts the LP catalyst on the MOF to minimize loss of LPs during catalysis and recycling. Our work reveals the enormous potential of MOFs as an appealing paradigm for the construction of efficient heterogeneous catalysts with interesting steric and size selectivity worthy of exploration. In addition, the strategies for anchoring a LP into a MOF as contributed herein can be readily applied for the task-specific design of functional catalysis materials for various applications. Lewis pairs (LPs), classical and frustrated, have been successfully introduced into and stabilized in a metal-organic framework (MOF). Benefiting from the robust framework and tunable porous structure of MOFs, the resultant MOF-LP demonstrates not only great recyclability but also excellent performance in the catalytic reduction of imines and hydrogenation of alkenes. The combination of LP and MOF therefore lays a foundation for developing a MOF-LP as a new paradigm for catalysis, particularly heterogeneous catalysis.
Hydrogenations at room temperature and atmospheric pressure with mesoionic carbene-stabilized borenium catalysts
Eisenberger, Patrick,Bestvater, Brian P.,Keske, Eric C.,Crudden, Cathleen M.
supporting information, p. 2467 - 2471 (2015/02/19)
1,2,3-Triazolylidene-based mesoionic carbene boranes have been synthesized in a convenient one-pot protocol from the corresponding 1,2,3-triazolium salts, base, and borane. Borenium ions are obtained by hydride abstraction and serve as catalysts in mild hydrogenation reactions of imines and unsaturated N-heterocycles at ambient pressure and temperature.
Copper-catalyzed oxaziridine-mediated oxidation of C-H bonds
Motiwala, Hashim F.,Guelgeze, Belgin,Aube, Jeffrey
experimental part, p. 7005 - 7022 (2012/10/08)
The highly regio- and chemoselective oxidation of activated C-H bonds has been observed via copper-catalyzed reactions of oxaziridines. The oxidation proceeded with a variety of substrates, primarily comprising allylic and benzylic examples, as well as one example of an otherwise unactivated tertiary C-H bond. The mechanism of the reaction is proposed to involve single-electron transfer to the oxaziridines to generate a copper-bound radical anion, followed by hydrogen atom abstraction and collapse to products, with regeneration of the catalyst by a final single-electron transfer event. The involvement of allylic radical intermediates was supported by a radical-trapping experiment with TEMPO.
Taking the F out of FLP: Simple lewis acid-base pairs for mild reductions with neutral boranes via borenium ion catalysis
Eisenberger, Patrick,Bailey, Adrian M.,Crudden, Cathleen M.
supporting information, p. 17384 - 17387 (2013/01/15)
Discrete three-coordinate borenium salts 1c and 1d are accessed by cooperative Lewis acid-base pair-mediated heterolytic splitting of the B-H bond in pinacolborane by B(C6F5)3DABCO and Ph 3C+/DABCO, respectively. The resulting salts are competent catalysts in the reduction of a broad range of imines and can be generated in situ. Moreover, a mechanistic framework for borenium catalysis based on experimental evidence is proposed. The reaction is suggested to proceed by borenium activation of the imine substrate followed by counterintuitive hydride delivery from HBPin (with the assistance of DABCO) rather than from the HB(C6F5)3- anion, contrary to typical mechanisms of reduction in FLP systems.
Rhodium-Catalyzed Asymmetric [5+2] Cycloaddition of Alkyne- Vinylcyclopropanes
Shintani, Ryo,Nakatsu, Hiroki,Takatsu, Keishi,Hayashi, Tamio
supporting information; experimental part, p. 8692 - 8694 (2010/03/24)
The development of such an asymmetric catalysis by the use of a rhodium complex coordinated with chiral phosphoramidite ligand, achieving very high enantiomeric excesses has been reported. Transition-metal-catalyzed cycloaddition of vinylcyclopropanes wit
Stereoselective synthesis of spirooxindoles by palladium-catalyzed decarboxylative cyclization of γ-methylidene-β-valerolactones with isatins
Shintani, Ryo,Hayashi, Shin-Ya,Murakami, Masataka,Takeda, Momotaro,Hayashi, Tamio
supporting information; experimental part, p. 3754 - 3756 (2011/02/28)
Image Presented A new synthetic method of spirooxindole derivatives has been developed by way of a palladium-catalyzed decarboxylative cyclization of γ-methylidene-β-valerolactones with isatins. By employing a newly prepared phosphoramidite ligand, the re
UNEXPECTED PRODUCTS IN A KABACHNIK-FIELDS SYNTHESIS OF AMINOPHOSPHONATES
Gancarz, Roman
, p. 59 - 64 (2007/10/02)
In a Kabachnik-Fields synthesis of aminophosphonates derived from aromatic ketones the formation of hydroxyphosphonates, their rearrangement to corresponding phosphates and amine promoted decomposition of the last, leads to a number of unexpected products, which in some cases could be the only products of reaction.Key words: 1-Aminophosphonates; 1-hydroxyphosphonates; Kabachnik-Fields reaction; phosphonate-phosphate rearrangement.
Photochemical Reduction and Decomposition of Benzpinacolone N-Benzhydrylimine
Giri, B. P.,Mehrotra, K. N.
, p. 806 - 807 (2007/10/02)
Irradiation of a 2-propanol solution of benzpinacolone N-benzhydrylimine (I) affords triphenylmethane (II), 9-phenylfluorene (III), 1,2,2,2-tetraphenylethylbenzhydrylamine (IV), diphenylmethane (V), dibenzhydrylamine (VI) and 1,1,2,2-tetraphenylethylamine (VII).
