نتایج جستجو برای: βunsaturated ketones moieties

تعداد نتایج: 19705  

Journal: :Journal of the American Chemical Society 2002
K C Nicolaou T Montagnon T Ulven P S Baran Y-L Zhong F Sarabia

New synthetic technologies for the preparation and elaboration of alpha-tosyloxy ketones in solution- and on solid-phase are described. Both olefins and ketones serve as precursors to these relatively stable chemical entities: olefins via a novel one-pot epoxidation, arylsulfonic acid displacement, and oxidation sequence, and ketones by direct exposure to arylsulfonic acids in the presence of d...

Journal: :Physical chemistry chemical physics : PCCP 2014
Jihad Badra Ahmed E Elwardany Aamir Farooq

Reaction rate constants of the reaction of four large ketones with hydroxyl (OH) are investigated behind reflected shock waves using OH laser absorption. The studied ketones are isomers of hexanone and include 2-hexanone, 3-hexanone, 3-methyl-2-pentanone, and 4-methl-2-pentanone. Rate constants are measured under pseudo-first-order kinetics at temperatures ranging from 866 K to 1375 K and press...

Journal: :J. Chem. Soc., Trans. 1904

Journal: :Organic & biomolecular chemistry 2011
Cheng-Yan Ni Sha-Sha Kan Quan-Zhong Liu Tai-Ran Kang

Highly diastereoselective and enantioselective catalytic capture of chiral zinc enolates using nitroolefins as electrophiles is described. The tandem products γ-nitro ketones were obtained in good yields with high diastereoselectivities and enantioselectivities. The γ-nitro ketones were readily hydrogenated to the optically enriched and diastereomerically pure chiral pyrrolidines with four cont...

2017
Desta Doro Bume Cody Ross Pitts Fereshte Ghorbani Stefan Andrew Harry Joseph N. Capilato Maxime A. Siegler Thomas Lectka

The ubiquitous ketone carbonyl group generally deactivates substrates toward radical-based fluorinations, especially sites closest to it. Herein, ketones are used instead to direct aliphatic fluorination using Selectfluor, catalytic benzil, and visible light. Selective band g-fluorination are demonstrated on rigid mono-, di-, tri-, and tetracyclic (steroidal) substrates employing both cyclic an...

Journal: :The Journal of organic chemistry 2013
Qinghe Gao Xia Wu Fengcheng Jia Meicai Liu Yanping Zhu Qun Cai Anxin Wu

An I2/KOH synergistically promoted direct ring-opening aroylation of benzothiazoles with aryl ketones has been discovered. Aryl ketones were seen to act as carbonyl sources to construct 2-acylbenzothiazoles. This reaction could provide an example for the convergent integration of self-labor domino sequences based on an in situ cross-trapping strategy.

Journal: :Chemical communications 2012
Yutian Shao Chao Yang Weijun Gui Yang Liu Wujiong Xia

Irradiation of terminal aromatic γ,δ-epoxy ketones with a 450 W UV lamp led to Norrish type II cyclization/semi-pinacol rearrangement cascade reaction which formed the benzocyclobutanones containing a full-carbon quaternary center, whereas irradiation of substituted aromatic γ,δ-epoxy ketones led to the indanones through a photochemical epoxy rearrangement and 1,5-biradicals cyclization tandem ...

Journal: :Organic & biomolecular chemistry 2012
Chubei Wang Chao Xu Xiaosong Tan Hao Peng Hongwu He

A highly practical, catalytic enantioselective cyclic phosphite addition to aldehydes and ketones was developed. The reaction rate of the asymmetric hydrophosphonylation was significantly enhanced by the addition of silver carbonate. Particularly, significant improvement has been achieved on the asymmetric hydrophosphonylation of unactivated ketones, giving quaternary α-hydroxy phosphonates wit...

2003
Kaoru Nakamura Rio Yamanaka Tomoko Matsuda Tadao Harada

Herein we review recent advances in the asymmetric reduction of ketones by biocatalysts. Included are discussions on recent developments in methodologies to control enantioselectivities of catalytic reactions, and examples of practical applications that reduce various types of ketones are also shown. © 2003 Elsevier Ltd. All rights reserved.

Journal: :Chemical communications 2015
Wei-Peng Liu Ming-Lei Yuan Xiao-Hui Yang Ke Li Jian-Hua Xie Qi-Lin Zhou

Highly efficient iridium catalyzed asymmetric transfer hydrogenation of simple ketones with ethanol as a hydrogen donor has been developed. By using chiral spiro iridium catalysts (S)- a series of alkyl aryl ketones were hydrogenated to chiral alcohols with up to 98% ee.

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