24825-01-2Relevant academic research and scientific papers
Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
, (2019/08/30)
Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
The Activation of Carboxylic Acids via Self-Assembly Asymmetric Organocatalysis: A Combined Experimental and Computational Investigation
Monaco, Mattia Riccardo,Fazzi, Daniele,Tsuji, Nobuya,Leutzsch, Markus,Liao, Saihu,Thiel, Walter,List, Benjamin
, p. 14740 - 14749 (2016/11/18)
The heterodimerizing self-assembly between a phosphoric acid catalyst and a carboxylic acid has recently been established as a new activation mode in Br?nsted acid catalysis. In this article, we present a comprehensive mechanistic investigation on this activation principle, which eventually led to its elucidation. Detailed studies are reported, including computational investigations on the supramolecular heterodimer, kinetic studies on the catalytic cycle, and a thorough analysis of transition states by DFT calculations for the rationalization of the catalyst structure-selectivity relationship. On the basis of these investigations, we developed a kinetic resolution of racemic epoxides, which proceeds with high selectivity (up to s = 93), giving the unreacted epoxides and the corresponding protected 1,2-diols in high enantiopurity. Moreover, this approach could be advanced to an unprecedented stereodivergent resolution of racemic α-chiral carboxylic acids, thus providing access to a variety of enantiopure nonsteroidal anti-inflammatory drugs and to α-amino acid derivatives.
Heterogenisation of ketone catalysts within mesoporous supports for asymmetric epoxidation
Brown, Lynda J.,Brown, Richard C. D.,Raja, Robert
, p. 843 - 850 (2013/03/28)
The synthesis of the first mesoporous silica (150 A) anchored carbohydrate-derived chiral ketone is described. This new heterogeneous catalyst has been shown to be effective in the asymmetric epoxidation of olefins by oxone. The heterogeneous ketone catalyst has comparable activity to that of its homogeneous counterpart and returned enantioselectivities up to 90% e.e.
Asymmetric epoxidation with a photoactivated [Ru(salen)] complex
Nakata, Kenya,Takeda, Tsuyoshi,Mihara, Jun,Hamada, Tetsuya,Irie, Ryo,Katsuki, Tsutomu
, p. 3776 - 3782 (2007/10/03)
(Nitrosyl)(salen)ruthenium(II) complex 1 was found to serve as an efficient catalyst for the epoxidation of conjugated olefins under photoirradiation, with 2,6-dichloropyridine N-oxide (2) or tetramethylpyrazine N,N′-dioxide as a stoichiometric oxidant. High enantioselectivity was achieved irrespective of the substitution pattern of olefins. The choice of solvent depends on stability of the resulting epoxides: high enantioselectivity is generally observed in the reaction with ethereal solvents, but use of benzene is recommended when the resulting epoxides are acid-sensitive.
Ru-salen catalyzed asymmetric epoxidation: Photoactivation of catalytic activity
Takeda, Tsuyoshi,Irie, Ryo,Shinoda, Yo,Katsuki, Tsutomu
, p. 1157 - 1159 (2007/10/03)
(ON+)(Salen)ruthenium(II) complex 1 was found to be an efficient catalyst for the epoxidation of conjugated olefins under sunlight coming through windows or incandescent light. The most suitable terminal oxidant was 2,6-dichloropyridine N-oxide 2. All the examined conjugated olefins showed high enantioselectivity greater than 80% ee, irrespective of their substitution pattern.
Photo-controlled Lewis acidity: Chiral (ON)Ru-salen catalyzed hetero Diels-Alder reaction and kinetic resolution of racemic epoxides
Mihara, Jun,Hamada, Tetsuya,Takeda, Tsuyoshi,Irie, Ryo,Katsuki, Tsutomu
, p. 1160 - 1162 (2007/10/03)
(ON+)(Salen)ruthenium(II) complex 1 serves as a chiral Lewis acid catalyst for asymmetric hetero Diels-Alder reaction and for kinetic resolution of racemic epoxides when the reactions were carried out under sunlight coming through windows or incandescent light.
Asymmetric cyclopropanation of olefins with diazoacetate using chiral copper catalysts
Ichiyanagi, Tsuyoshi,Shimizu, Makoto,Fujisawa, Tamotsu
, p. 9599 - 9610 (2007/10/19)
Chiral 2-(2-aryl- or 2-alkyl-sufonylamino)phenyl-4-phenyl-1,3-oxazolines were found to be effective ligands for copper-catalyzed enantioselective cyclopropanation reaction of olefins. The reaction of styrene with d-menthyl diazoacetate in the presence of optically active copper catalysts gave cyclopropanation products in a ratio of trans: cis = 83: 17 with 63% ee (trans) and 84% ee (cis).
Microbiological transformations. 31: Synthesis of enantiopure epoxides and vicinal diols using fungal epoxide hydrolase mediated hydrolysis
Pedragosa-Moreau,Archelas,Furstoss
, p. 3319 - 3322 (2007/10/03)
The enantioselective hydrolysis of epoxyindene and dihydronaphtalene epoxides by the fungus Beauveria sulfurescens (ATCC 7159) is described. This allowed the preparation of both these epoxides, as well as of the corresponding diols, in good to excellent enantiomeric purity.
