نتایج جستجو برای: chemoselective

تعداد نتایج: 1372  

2014
Chathurika R. K. Jayasundara Jason M. Unold Jossian Oppenheimer Milton R. Smith Robert E. Maleczka

A two-step Ir-catalyzed borylation/Pd-catalyzed dehalogenation sequence allows for the net synthesis of fluoroarenes where the boronic ester is ortho to fluorine. Key elements of this approach include the use of a halogen para to the fluorine to block meta Ir-catalyzed borylation and the chemoselective Pd-catalyzed dehalogenation by KF activated polymethylhydrosiloxane (PMHS).

Journal: :Organic letters 2016
Mu-Wang Chen Bo Wu Zhang-Pei Chen Lei Shi Yong-Gui Zhou

A highly enantioselective synthesis of chiral fluorinated propargylamines was developed through phosphoric acid and ruthenium-catalyzed chemoselective biomimetic hydrogenation of the carbon-nitrogen double bond of fluorinated alkynyl ketimines in the presence of a carbon-carbon triple bond. This reaction features high chemoselectivity and slow background reaction. In addition, selective transfo...

2011
Nuria García Patricia García-García Manuel A. Fernández-Rodríguez Rubén Rubio María R. Pedrosa Francisco J. Arnáiz Roberto Sanz

Pinacol is described as a new chemoselective and environmentally benign reducing agent for sulfoxides and nitroaromatics assisted by readily available dichlorodioxomolybdenum(VI) complexes as catalysts. A wide range of substrates including those bearing challenging functional groups have been efficiently and selectively reduced being acetone and water the only byproducts of these reactions.

Journal: :Chemical communications 2014
Maciej Stodulski Alissa Goetzinger Stefanie V Kohlhepp Tanja Gulder

The nucleophilicity of the substituents in iodobenzene pre-catalysts have a huge impact on product selectivity in iodine(III) triggered halogenations, steering the reactivity from solely carbocyclizations towards dihalogenations. Utilizing this catalyst-dependent reactivity a diastereo- and chemoselective dihalogenation method was established allowing the conversion of structurally and electron...

Journal: :Chemical communications 2012
Yu-Ting Lee Yeong-Jiunn Jang Siang-en Syu Shu-Chi Chou Chia-Jui Lee Wenwei Lin

A general preparation of new types of benzofurans, benzothiophenes and indoles is realized via chemoselective intramolecular Wittig reactions with the corresponding ester, thioester and amide functionalities using in situ formed phosphorus ylides as key intermediates. The reaction conditions are very mild, and numerous Michael acceptors and commercially available acid chlorides can be applied v...

Journal: :Carbohydrate research 2003
Tülay Polat Robert J Linhardt

A simple and efficient method is developed for the chemoselective one-pot conversion of ethers (benzyl, TBDMS and acetal) to the corresponding benzoates by zinc triflate-catalyzed deprotection and benzoylation by benzoyl bromide. In the same reaction, methyl or p-methoxyphenyl glycosides are converted into glycosyl bromides that are useful in glycosylation reactions.

2016
Hyungjun Lee Yue Yuan Inmoo Rhee Timothy W. Corson Seung-Yong Seo

Naturally occurring homoisoflavonoids containing either 5,7-dihydroxy-6-methoxy or 7-hydroxy-5,6-dimethoxy groups such as the antiangiogenic homoisoflavanone, cremastranone, were synthesized via three or four linear steps from the known 4-chromenone. This facile synthesis includes chemoselective 1,4-reduction of 4-chromenone and selective deprotection of 3-benzylidene-4-chromanone a containing ...

Journal: :Chemical communications 2011
Damien Crépin Coralie Tugny James H Murray Christophe Aïssa

Mild intramolecular hydroacylation of α,α-disubstituted 4-alkylidenecyclopropanals has been developed, avoiding decarbonylation and affording cycloheptenones in good yields. The reaction is chemoselective in favour of the alkylidenecyclopropane moiety when potential alkene or alkyne acceptors are tethered to the substrate.

Journal: :Angewandte Chemie 2000
Marx Yamamoto

Superacid-derived aluminum catalysts R(2)AlNTf(2) (2 - 5 mol%) are highly efficient and versatile and are suitable promoters for the allylation and pentadienylation of aldehydes, aldol reactions, aldol cross-coupling of ketones, and Michael additions (several products are shown). Furthermore, they can be converted into chemoselective Lewis acids. Tf=trifluoromethanesulfonyl.

Journal: :Chemical communications 2011
Fan Yang Tienan Jin Ming Bao Yoshinori Yamamoto

A facile, efficient, and general synthetic method for 3,4-dihalofurans has been developed via the electrophilic iodocyclization of various 4-hydroxy-2-but-2-yn-1-ones. The use of MeOH as a solvent is crucial for the efficient chemoselective synthesis of the corresponding 3,4-dihalofurans.

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