26452-98-2Relevant articles and documents
Investigations into the C-deuteriation of enol acetates derived from aryl alkyl ketones
Buksha, Svitlana,Coumbarides, Gregory S.,Dingjan, Marco,Eames, Jason,Suggate, Michael J.,Weerasooriya, Neluka
, p. 337 - 352 (2005)
Results are reported on the regioselective C-deuteriation of a series of enol acetates (derived from the aryl alkyl ketones) using molecular deuterium as the D-source and palladium-on-barium sulphate as the mediator. The results presented highlight potent
Identification of an Esterase Isolated Using Metagenomic Technology which Displays an Unusual Substrate Scope and its Characterisation as an Enantioselective Biocatalyst
Gavin, Declan P.,Murphy, Edel J.,Foley, Aoife M.,Castilla, Ignacio Abreu,Reen, F. Jerry,Woods, David F.,Collins, Stuart G.,O'Gara, Fergal,Maguire, Anita R.
supporting information, p. 2466 - 2474 (2019/03/11)
Evaluation of an esterase annotated as 26D isolated from a marine metagenomic library is described. Esterase 26D was found to have a unique substrate scope, including synthetic transformations which could not be readily effected in a synthetically useful manner using commercially available enzymes. Esterase 26D was more selective towards substrates which had larger, more sterically demanding substituents (i. e. iso-propyl or tert-butyl groups) on the β-carbon, which is in contrast to previously tested commercially available enzymes which displayed a preference for substrates with sterically less demanding substituents (e.g. methyl group) at the β-carbon. (Figure presented.).
DMAP-based flexible polymer networks formed via Heck coupling as efficient heterogeneous organocatalysts
Xu, Wei,Xia, Wu,Guan, Yukun,Wang, Yiming,Lu, Cuifen,Yang, Guichun,Nie, Junqi,Chen, Zuxing
, p. 15 - 21 (2016/06/14)
Two DMAP-based flexible polymer networks TPB-DMAP and TPA-DMAP have been successfully synthesized via palladium catalyzed Heck cross-coupling. The structures of these polymers were confirmed by solid state 13C CP/MAS and Fourier transform infrared spectroscopy (FTIR). Although both polymers have negligible surface areas, they exhibit excellent catalytic efficiency for the acylation of 1-phenylethanol with acetic anhydride due to their good swelling capacities. Utilized as a typical catalyst, the polymer TPA-DMAP shows high activities for acylation of a variety of alcohols to the corresponding esters. Moreover, the catalyst can be recycled at least ten times without obvious loss of catalytic activity.
Efficient approach for the chemoselective acetylation of alcohols catalyzed by a novel metal oxide nanocatalyst CuO-ZnO
Albadi, Jalal,Alihosseinzadeh, Amir,Mardani, Mehdi
, p. 308 - 313 (2015/09/28)
A new method has been developed for the chemoselective acetylation of alcohols with acetic anhydride in the presence of phenols using a novel, recyclable CuO-ZnO nanocatalyst. The catalyst was synthesized using the co-precipitation method and characterized by N2 adsorption-desorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersion scanning analyses. Furthermore, this catalyst could be recycled up to six times without significant loss in its activity.
Chemoenzymatic synthesis of rasagiline mesylate using lipases
De Mattos, Marcos Carlos,De Fonseca, Thiago Sousa,Da Silva, Marcos Reinaldo,De Oliveira, Maria Da Concei??o Ferreira,De Lemos, Telma Leda Gomes,De Marques, Ricardo Araújo
, p. 76 - 82 (2015/05/04)
A straightforward chemoenzymatic synthesis of rasagiline mesylate has been developed. The key steps for the introduction of chirality involved kinetic enzymatic resolution with lipases via acetylation of racindanol and an inversion configuration Mitsunobu reaction of the produced (S)-indanol. Immobilized lipase from Thermomyces lanuginosus proved to be a robust biocatalyst in the kinetic resolution, leading to (S)-indanol with high selectivity (e.e. > 99%, E > 200) in just 15 min, at 35°C, in hexane, being reused for ten-times without significant loss of the activity and selectivity.
CAL-B-Catalyzed Enantioselective Deacetylation of Some Benzylic Acetate Derivatives Via Alcoholysis in Non-aqueous Media
Zadi, Amna,Merabet-Khelassi, Mounia,Aribi-Zouioueche, Louisa
, p. 1054 - 1061 (2015/02/05)
Enantioselective deacetylation of a set of benzylic acetates via alcoholysis catalyzed by Lipase B from Candida antarctica (CAL-B), under mild conditions is described. A systematic study allows to determine the appropriate combination nucleophile/organic solvent and also to explain the influence of these parameters on the enzymatic catalytic reaction. In all cases, (R)-alcohols are obtained with high ee (up to >99 %) at conversion 36 % 500. The enzymatic reactivity is influenced by the hydrophobicity of solvent and the structure/nature of the nucleophile. Furthermore, CAL-B allows enantio-complementary between transesterifications in non-aqueous media: alcoholysis and acetylation.
Allylic oxidation of alkenes catalyzed by a copper-aluminum mixed oxide
Garcia-Cabeza, Ana Leticia,Marin-Barrios, Ruben,Moreno-Dorado, F. Javier,Ortega, Maria J.,Massanet, Guillermo M.,Guerra, Francisco M.
supporting information, p. 1598 - 1601 (2014/04/17)
A strategy for the allylic oxidation of cyclic alkenes with a copper-aluminum mixed oxide as catalyst is presented. The reaction involves the treatment of an alkene with a carboxylic acid employing tert-butyl hydroperoxide as the oxidant. In all cases, the corresponding allylic esters are obtained. When l-proline is employed, the allylic alcohol or ketone is obtained. The oxidation of cyclohexene and valencene has been optimized by design of experiments (DoE) statistical methodology.
Efficient benzylic and aliphatic C-H oxidation with selectivity for methylenic sites catalyzed by a bioinspired manganese complex
Shen, Duyi,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
supporting information, p. 1108 - 1111 (2014/03/21)
A benzimidazole-based nonheme manganese complex efficiently catalyzes benzylic, aliphatic C-H as well as tertiary C-H oxidation with hydrogen peroxide as the oxidant in the presence of acetic acid as additive. 18O labeling experiments suggest the reaction may proceed via a high-valent manganese-oxo intermediate.
A green route to enantioenriched (S)-arylalkyl carbinols by deracemization via combined lipase alkaline-hydrolysis/Mitsunobu esterification
Houiene, Zahia,Merabet-Khelassi, Mounia,Bouzemi, Nassima,Riant, Olivier,Aribi-Zouioueche, Louisa
, p. 290 - 296 (2013/04/23)
Herein we report results of the chemoenzymatic deracemization of a range of secondary benzylic acetates 1a-9a via a sequence of hydrolysis with CAL-B lipase in non-conventional media, combined with esterification of the recovered alcohol according to the Mitsunobu protocol following an enzymatic kinetic resolution (KR). The KR of racemic acetates 1a-9a via an enzymatic hydrolysis, with CAL-B lipase and Na2CO3, in non-aqueous media was optimized and gave high selectivities (E ? 200) at good conversions (C >49%) for all of the substrates studied. This method competes well with the traditional one performed in a phosphate buffer solution. The deracemization using Mitsunobu inversion gave the (S)-acetates in moderate to excellent enantiomeric excess 75% ee 99%, in acceptable isolated yields 70% yield 89%, and with some variations according to the acetate structure.
Green methodology for enzymatic hydrolysis of acetates in non-aqueous media via carbonate salts
Merabet-Khelassi, Mounia,Houiene, Zahia,Aribi-Zouioueche, Louisa,Riant, Olivier
experimental part, p. 828 - 833 (2012/09/25)
Herein we report a new approach to enantiomerically enriched acetates using a lipase-catalyzed hydrolysis in non-aqueous media by alkaline carbonate salts. The use of sodium carbonate in the enzymatic hydrolysis with Candida antarctica lipase B (CAL-B) of racemic acetates shows a large enhancement of the reactivity and selectivity of this lipase. The role of the carbonate salts, the amount and the nature of the alkaline earth metal on the efficiency of this new pathway are investigated. The enzymatic kinetic resolution of acetates 1a-9a, by enzymatic-carbonate hydrolysis under mild conditions is described. In all cases, the resulting alcohols and remaining acetates were obtained in high ee values (up to >99%) while the selectivities reached E >500.
