نتایج جستجو برای: preparation of ketones

تعداد نتایج: 21170795  

2018
Hui Liu Bi-Shuang Chen Fayene Zeferino Ribeiro de Souza Lan Liu

Whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to optically active alcohols. Currently, most of the whole-cell catalytic performance involves resting cells rather than growing cell biotransformation, which is one-step process that benefits from the simultaneous growth and biotransformation, eliminating the need for catalysts preparation. In this paper, asymme...

2017
Tsuneo Imamoto

The asymmetric hydrogenation of prochiral unsaturated compounds, such as alkenes, ketones, and imines, is one of the most efficient and straightforward methods for the preparation of optically active compounds. This method uses dihydrogen and small amounts of chiral transition metal complexes and is now recognized as economical, operationally simple, and environmentally friendly. It is frequent...

Journal: :Chemical science 2015
Valentín Hornillos Massimo Giannerini Carlos Vila Martín Fañanás-Mastral Ben L Feringa

A catalytic method for the direct cross-coupling of alkenyllithium reagents with aryl and alkenyl halides is described. The use of a catalyst comprising Pd2(dba)3/XPhos allows for the stereoselective preparation of a wide variety of substituted alkenes in high yields under mild conditions. In addition (1-ethoxyvinyl)lithium can be efficiently converted into substituted vinyl ethers which, after...

2015
Valentín Hornillos Massimo Giannerini Carlos Vila Martín Fañanás-Mastral Ben L. Feringa

A catalytic method for the direct cross-coupling of alkenyllithium reagents with aryl and alkenyl halides is described. The use of a catalyst comprising Pd2(dba)3/XPhos allows for the stereoselective preparation of a wide variety of substituted alkenes in high yields under mild conditions. In addition (1-ethoxyvinyl) lithium can be efficiently converted into substituted vinyl ethers which, afte...

Journal: :The Journal of organic chemistry 2012
Martyn Inman Anna Carbone Christopher J Moody

In a new variation on the Fischer indole synthesis, readily available haloarenes are converted into a wide range of indoles in just two steps by halogen-magnesium exchange and quenching with di-tert-butyl azodicarboxylate, followed by reaction with aldehydes or ketones under acidic conditions. The protocol, which is readily extended to the preparation of indole isosteres, 4- and 6-azaindoles an...

2010
Marco Pacenti Stefano Dugheri Pietro Traldi Filippo Degli Esposti Nicola Perchiazzi Elena Franchi Massimo Calamante Ireneo Kikic Paolo Alessi Alice Bonacchi Edoardo Salvadori Giulio Arcangeli Vincenzo Cupelli

The present research is focused on automation, miniaturization, and system interaction with high throughput for multiple and specific Direct Immersion-Solid Phase Microextraction/Fast Gas Chromatography analysis of the urinary ketones. The specific Mass Spectrometry instrumentation, capable of supporting such the automated changeover from Negative Chemical to Electron Ionization mode, as well a...

Journal: :Organic & biomolecular chemistry 2012
Tom Mejuch Bishnu Dutta Mark Botoshansky Ilan Marek

The combined carbometalation-zinc homologation-allylation reaction of the resulting stereodefined 3,3-disubstituted allylmetal species with ketones allow the preparation of allylic vicinal diol derivatives in good yields with excellent diastereomeric ratios from commercially available alkynes. Two adjacent quaternary centers are formed with the concomitant formation of three new carbon-carbon b...

Journal: :Journal of the American Chemical Society 2009
Sang Min Lim Nicholas Hill Andrew G Myers

We describe a synthetic sequence that allows for the preparation of optically active trans-1,2-diol monosilyl ether derivatives from ketones, providing a new means for retrosynthetic simplification of differentiated diol and polyol targets. The sequence involves silyl enol ether formation, Shi asymmetric epoxidation, and then regio- and stereospecific addition of hydride, methide, or higher alk...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - دانشکده علوم 1389

fluorescence chemical sensors for the highly sensitive and selective determination of pb2+ , hg2+, co2+ and fe3+ ions in aqueous solutions are described. the ion sensing system was prepared by incorporating lipophilic ligand (l) as a neutral ion-selective fluoroionophore in the plasticized pvc membrane containing sodium tetraphenylborate or potasium tetrakis (p-chlorophenyl) borate as a liphoph...

Journal: :Angewandte Chemie 2014
Jeffrey S Arnold Edward T Mwenda Hien M Nguyen

Dynamic kinetic asymmetric amination of branched allylic acetimidates has been applied to the synthesis of 2-alkyl-dihydrobenzoazepin-5-ones. These seven-membered-ring aza ketones are prepared in good yield with high enantiomeric excess by rhodium-catalyzed allylic substitution with 2-amino aryl aldehydes followed by intramolecular olefin hydroacylation of the resulting alkenals. This two-step ...

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