نتایج جستجو برای: ketones

تعداد نتایج: 9200  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2010
Anthony Mastracchio Alexander A Warkentin Abbas M Walji David W C MacMillan

The first enantioselective organocatalytic α-allylation of cyclic ketones has been accomplished via singly occupied molecular orbital catalysis. Geometrically constrained radical cations, forged from the one-electron oxidation of transiently generated enamines, readily undergo allylic alkylation with a variety of commercially available allyl silanes. A reasonable latitude in both the ketone and...

1999
C. Jo D. U. Ahn

Release of volatiles in oil emulsion systems containing various fat contents was determined using purge-and-trap dynamic headspace/gas chromatography. Oil emulsions were prepared using 0, 0.5, 1, 2, 4, or 8% oil, and a standard mixture was prepared using hydrocarbons, aldehydes, ketones, and alcohols. Fat content in oil emulsions reduced the volatility of added volatile standards, and the amoun...

2016
Muhamad Ali K Shakhatreh Mousa L Al-Smadi Omar F Khabour Fatima A Shuaibu Emad I Hussein Karem H Alzoubi

Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-(N,N-dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones we...

2014
Yue Qiao Zhaohua Gao Yong Liu Yan Cheng Mengxiao Yu Lingling Zhao Yixiang Duan Yu Liu

BACKGROUND Acetone, β -hydroxybutyric acid, and acetoacetic acid are three types of ketone body that may be found in the breath, blood, and urine. Detecting altered concentrations of ketones in the breath, blood, and urine is crucial for the diagnosis and treatment of diabetic ketosis. The aim of this study was to evaluate the advantages of different detection methods for ketones, and to establ...

Journal: :Applied and environmental microbiology 2009
Jessica Rehdorf Christian L Zimmer Uwe T Bornscheuer

While the number of available recombinant Baeyer-Villiger monooxygenases (BVMOs) has grown significantly over the last few years, there is still the demand for other BVMOs to expand the biocatalytic diversity. Most BVMOs that have been described are dedicated to convert efficiently cyclohexanone and related cyclic aliphatic ketones. To cover a broader range of substrate types and enantio- and/o...

Journal: :Chemical communications 2012
Peng Wang Chun-Rong Liu Xiu-Li Sun Shuai-Shuai Chen Jun-Fang Li Zuowei Xie Yong Tang

A newly designed PE-supported arsine has been developed as an excellent catalyst for catalytic Wittig-type olefination. Simple ketones, in particular inactive ketones prove to be suitable substrates for the first time. This reaction provides an easy access to di-, tri-, and tetra-substituted olefins in high yield.

Journal: :Organic & biomolecular chemistry 2015
William J Kerr David M Lindsay Vipulkumar K Patel Muralikrishnan Rajamanickam

Efficient conversion of ketones into kinetic enol phosphates under mild and accessible conditions has been realised using the developed methods with di-tert-butylmagnesium and bismesitylmagnesium. Optimisation of the quench protocol resulted in high yields of enol phosphates from a range of cyclohexanones and aryl methyl ketones, with tolerance of a range of additional functional units.

Journal: :Chemical communications 2008
Marco Bandini Riccardo Sinisi Achille Umani-Ronchi

Remarkable generality in scope of new C9-benzoylcupreines bearing electron-withdrawing substituents for the nitroaldol condensation with fluoromethyl ketones is presented. Both tri- and difluoromethyl ketones provided excellent levels of stereoinduction (ee 76-99%) under mild reaction conditions and low loading of catalyst (1-5 mol%).

Journal: :Organic & biomolecular chemistry 2014
You-Qing Wang Xiao-Yu Cui Yuan-Yuan Ren Yongna Zhang

A highly enantioselective direct Mannich reaction of methyl alkyl ketones with cyclic imines benzo[e][1,2,3]oxathiazine 2,2-dioxides, catalyzed by the combination of cinchona alkaloid derived primary amine and TFA, is disclosed. For unsymmetrical methyl alkyl ketones, it is favoured that specific regioselective addition to the imine substrates occurs at the less-substituted methyl group by ster...

2014
Tulaza Vaidya Ryan Cheng Peter N. Carlsen Alison J. Frontier Richard Eisenberg

A heterogeneous gold catalyst with remarkable activity for promoting the electrophilic reactions of aryl vinyl ketones and aryl dienyl ketones is described. The catalyst is easy to prepare, is robust, and can be recycled. Low loadings are effective for different types of cationic reactions, including Nazarov cyclizations, lactonizations, and [1,2] shifts.

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