نتایج جستجو برای: regioselectivity

تعداد نتایج: 1520  

Journal: :Chemical communications 2009
Sae Young Yun Saron Catak Won Koo Lee Matthias D'hooghe Norbert De Kimpe Veronique Van Speybroeck Michel Waroquier Yongeun Kim Hyun-Joon Ha

The ring opening of 2-substituted N,N-dibenzylaziridinium ions by bromide exclusively occurs at the substituted aziridine carbon atom in a stereospecific way, whereas the opposite regioselectivity was observed for hydride-induced ring opening at the unsubstituted position; furthermore, this unprecedented hydride-promoted reactivity was validated by means of Density Functional Theory (DFT) calcu...

Journal: :Chemical communications 2014
Weili Si Shirong Lu Naoki Asao Ming Bao Yoshinori Yamamoto Tienan Jin

We have demonstrated that NBS is able to promote the oxidation of fullerene monoradicals to form 1,4-difunctional fullerenes. The singly bonded fullerene dimers were used as fullerene monoradical precursors, which produced various 1,4-fullerenes with a wide range of functional groups in good to high yields with high regioselectivity in terms of cosolvents and nucleophiles.

Journal: :Organic letters 2006
Naidu S Chowdari Moballigh Ahmad Klaus Albertshofer Fujie Tanaka Carlos F Barbas

[reaction: see text] Organocatalytic asymmetric Mannich reaction of protected amino ketones with imines in the presence of an L-proline-derived tetrazole catalyst afforded diamines with excellent yields and enantioselectivities of up to 99%. The amino ketone protecting group controlled the regioselectivity of the reaction providing access to chiral 1,2-diamines from azido ketones and 1,4-diamin...

Journal: :Chemical science 2013
Osvaldo Gutierrez Jason G Harrison Ryan J Felix Fernando Cortés Guzman Michel R Gagné Dean J Tantillo

Quantum chemical calculations are used to explore the origins of regioselectivity for proton-, Pt(II)- and Pd(II)-promoted cyclizations of 1,5-hexadienes, 5-aminoalkenes, and allylic acetimidates. The strain associated with achieving carbonium ion-like transition state geometries is shown to be a key factor in controlling 5-exo vs. 6-endo selectivity.

Journal: :Chemical communications 2012
Jeffrey S Arnold Gregory T Cizio Drew R Heitz Hien M Nguyen

We report the chiral diene ligated rhodium-catalyzed dynamic kinetic asymmetric transformation (DYKAT) of racemic secondary allylic trichloroacetimidates with a variety of N-methyl anilines, providing allylic N-methyl arylamines in high yields, regioselectivity, and enantiomeric excess. The rhodium-catalyzed DYKAT method addresses limitations previously associated with this particular class of ...

2017
Juraj Dobiaš Marek Ondruš Gabriela Addová Andrej Boháč

3-Acylmethylidene-3,4-dihydroquinoxalin-2(1H)-ones are compounds which possess a wide range of physical and pharmaceutical applications. These compounds can be easily prepared by cyclocondensation of o-phenylenediamines and aroylpyruvates. Unsymmetrically substituted o-phenylenediamines can be obtained form regioisomeric mixtures of 3,4-dihydroquinoxalin-2(1H)-ones. It is often quite difficult ...

2016
Yanning Zheng Lingling Li Qiang Liu Haibo Zhang Yujin Cao Mo Xian Huizhou Liu

BACKGROUND Diols are important monomers for the production of plastics and polyurethanes, which are widely used in our daily life. The medium-chain diols with one hydroxyl group at its subterminal end are able to confer more flexibility upon the synthesized materials. But unfortunately, this type of diols has not been synthesized so far. The strong need for advanced materials impelled us to dev...

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