15040-96-7Relevant academic research and scientific papers
Fluorous bispidine: A bifunctional reagent for copper-catalyzed oxidation and knoevenagel condensation reactions in water
Ang, Wei Jie,Chng, Yong Sheng,Lam, Yulin
, p. 81415 - 81428 (2015/10/06)
Fluorous bispidine-type ligands have been developed to facilitate its recovery and reusability and to demonstrate its bifunctional property as a ligand and base in copper-catalyzed aerobic oxidation, the Knoevenagel condensation and tandem oxidation/Knoevenagel condensation in water under mild conditions. Application of the fluorous ligand was also extended to the surfactant-free copper-catalyzed allylic and benzylic sp3 C-H oxidation reaction in water. The fluorous ligands could be recovered using F-SPE with recovery ranging from 91-97% and could be reused five times with little loss of activity.
Acylammonium salts as dienophiles in diels-alder/lactonization organocascades
Abbasov, Mikail E.,Hudson, Brandi M.,Tantillo, Dean J.,Romo, Daniel
supporting information, p. 4492 - 4495 (2014/04/17)
α,I?-Unsaturated acylammonium salts, generated in situ from commodity acid chlorides and a chiral isothiourea organocatalyst, comprise a new and versatile family of chiral dienophiles for the venerable Diels-Alder (DA) cycloaddition. Their reactivity is unveiled through a highly diastereo- and enantioselective Diels-Alder/lactonization organocascade that generates cis- and trans-fused bicyclic I?- and I??-lactones bearing up to four contiguous stereocenters. Moreover, the first examples of DA-initiated, stereodivergent organocascades are described delivering complex scaffolds found in bioactive compounds. The origins of stereoselectivity are rationalized through computational studies. In addition, the utility of this methodology is demonstrated through a concise approach to the core structure of glaciolide and formal syntheses of fraxinellone, trisporic acids, and trisporols.
2-Quinoxalinol diamine Cu(II) complex: Facilitating catalytic oxidation through dual mechanisms
Li, Yuancheng,Lee, Taebum,Weerasiri, Kushan,Wang, Tanyu,Buss, Emily E.,McKee, Michael L.,Gorden, Anne E. V.
, p. 13578 - 13583 (2014/11/08)
The Cu(II) complex 1, Cu(II)-6-N-3,5-di-tert-butylsalicylidene-6,7- quinoxalinol-diamine, has been developed to address problems with current methods of catalytic oxidation using tert-butyl hydroperoxide (TBHP). Complex 1 demonstrated an increased capability to utilize TBHP while limiting interference from free radical reactions and was demonstrated to be highly effective in the oxidations of a variety of olefins. the Partner Organisations 2014.
Cyclometalation of anthyridine-based ligands with dirhodium acetates: Structure and catalytic activity
Huang, Da-Wei,Lo, Ying-Hao,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
, p. 4009 - 4015 (2013/08/23)
Coordination of 2,8-Ar2-5-phenylanthyridines (Ar = 2-thienyl, 1a; Ar = 2-ClC6H4-, 1b) with dirhodium tetraacetate yielded the cyclometalated complexes [Rh2(OAc)3(metalated- 1a)] (3a) and [Rh2(OAc)3(metalated-1b)] (3b), respectively. Under acidic conditions, cleavage of the Rh-C bond in 3a,b took place to give the corresponding coordination complexes 4a,b. Treatment of 3a,b with PPh3 led to the phosphine-cyclometalated species [Rh 2(OAc)2{P,C-(C6H4)PPh 2}(metalated-1a)] (5a) and [Rh2(OAc)2{P,C- (C6H4)PPh2}(metalated-1b)] (5b), respectively. These new dirhodium complexes have been structurally characterized by NMR spectroscopy, and some representative compounds were also analyzed by X-ray methods. The use of these newly prepared dirhodium complexes as catalysts for the allylic oxidation of cyclohexenes was investigated.
Allylic C-H activations using Cu(II) 2-quinoxalinol salen and tert-butyl hydroperoxide
Li, Yuancheng,Lee, Tae Bum,Wang, Tanyu,Gamble, Audrey V.,Gorden, Anne E. V.
experimental part, p. 4628 - 4633 (2012/08/08)
Using a Cu(II) 2-quinoxalinol salen complex as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant, allylic activations of olefin substrates can be converted to the corresponding enones or 1,4-enediones. Excellent yields can be achieved (up to 99%) within a very short reaction time and with great tolerance for additional functional groups. Possible mechanistic pathways have been characterized using Raman spectroscopy, cyclic voltammetry, and theoretical calculations.
Allylic oxidations catalyzed by dirhodium caprolactamate via aqueous tert-butyl hydroperoxide: The role of the tert-butylperoxy radical
McLaughlin, Emily C.,Choi, Hojae,Wang, Kan,Chiou, Grace,Doyle, Michael P.
experimental part, p. 730 - 738 (2009/07/04)
Dirhodium(II) caprolactamate exhibits optimal efficiency for the production of the tert-butylperoxy radical, which is a selective reagent for hydrogen atom abstraction. These oxidation reactions occur with aqueous tert-butyl hydroperoxide (TBHP) without rapid hydrolysis of the caprolactamate ligands on dirhodium. Allylic oxidations of enones yield the corresponding enedione in moderate to high yields, and applications include allylic oxidations of steroidal enones. Although methylene oxidation to a ketone is more effective, methyl oxidation to a carboxylic acid can also be achieved. The superior efficiency of dirhodium(II) caprolactamate as a catalyst for allylic oxidations by TBHP (mol % of catalyst, % conversion) is described in comparative studies with other metal catalysts that are also reported to be effective for allylic oxidations. That different catalysts produce essentially the same mixture of products with the same relative yields suggests that the catalyst is not involved in product-forming steps. Mechanistic implications arising from studies of allylic oxidation with enones provide new insights into factors that control product formation. A previously undisclosed disproportionation pathway, catalyzed by the tert-butoxy radical, of mixed peroxides for the formation of ketone products via allylic oxidation has been uncovered.
Allylic Oxidations Catalyzed by Dirhodium Catalysts under Aqueous Conditions
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Page/Page column 14-16, (2009/04/24)
The present invention relates to compositions and methods for achieving the efficient allylic oxidation of organic molecules, especially olefins and steroids, under aqueous conditions. The invention concerns the use of dirhodium (II,II) “paddlewheel complexes, and in particular, dirhodium carboximate and tert-butyl hydroperoxide as catalysts for the reaction. The use of aqueous conditions is particularly advantageous in the allylic oxidation of 7-keto steroids, which could not be effectively oxidized using anhydrous methods, and in extending allylic oxidation to enamides and enol ethers.
A new dirhodium tetraacetate carbenoid: Synthesis, crystal structure and catalytic application
Na, Sung Jae,Lee, Bun Yeoul,Bui, Nhat-Nguyen,Mho, Sun-il,Jang, Hye-Young
, p. 5523 - 5527 (2008/03/12)
A new dirhodium tetraacetate II involving 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene I was synthesized and characterized by general spectroscopic tools in the solution state as well as single X-ray crystallographic analysis in the solid state. The catalytic activity of dirhodium tetraacetate carbenoid II was tested for the allylic oxidation, and the improved reactivity to the allylic oxidation was observed compared to that of Rh2(OAc)4. The different electrochemical properties of dirhodium tetraacetate carbenoid II and Rh2(OAc)4 were compared via cyclic voltammetry.
Dirhodium(II) caprolactamate: An exceptional catalyst for allylic oxidation
Catino, Arthur J.,Forslund, Raymond E.,Doyle, Michael P.
, p. 13622 - 13623 (2007/10/03)
The oxidation of organic molecules represents a fundamentally important chemical process. Particularly important is allylic oxidation, whereby a single methylene unit is converted directly into a carbonyl group. In this communication, we report that dirhodium(II) caprolactamate [Rh2(cap)4] in combination with tert-butyl hydroperoxide (terminal oxidant) effectively catalyzes the allylic oxidation of a variety of olefins and enones. The reaction is completely selective, tolerant of air/moisture, and can be performed with as little as 0.1 mol % catalyst in minutes. A mechanistic proposal involving redox chain catalysis has been put forth, as well as evidence for the intermediacy of a higher valent dirhodium tert-butyl peroxy complex. Copyright
