نتایج جستجو برای: enantioselectivity

تعداد نتایج: 1696  

Journal: :Organic & biomolecular chemistry 2011
Magnus Rueping Thomas Theissmann Mirjam Stoeckel Andrey P Antonchick

A convenient protocol for the enantioselective synthesis of 4-substituted tetrahydroquinolines has been developed. Chiral BINOL phosphoric acids promote the reduction of a wide range of 4-substituted quinolines with Hantzsch esters with good to high levels of enantioselectivity.

Journal: :Chemical communications 2012
Soyoung Park Keiichi Ikehata Ryo Watabe Yuta Hidaka Arivazhagan Rajendran Hiroshi Sugiyama

We describe asymmetric intramolecular Friedel-Crafts alkylations with a DNA-based hybrid catalyst and propose a plausible binding model. This study shows promise for studying relationships between the helical chirality of DNA and enantioselectivity of the chemical reaction.

Journal: :Chemical communications 2011
Morifumi Fujita Mikimasa Wakita Takashi Sugimura

Optically active 1,3-dioxolan-2-yl cation intermediates were generated during enantioselective dioxyacetylation of alkene with chiral hypervalent iodine(III). Regioselective attack of a nucleophile toward the intermediate resulted in reversal of enantioselectivity of the dioxyacetylation.

Journal: :Organic & biomolecular chemistry 2012
David J Aitken Angela M Bernard Francesca Capitta Angelo Frongia Régis Guillot Jean Ollivier Pier Paolo Piras Francesco Secci Marco Spiga

N-Phenylsulfonyl (S)-proline catalyzes the direct aldol reaction of 3-substituted cyclobutanones and aryl aldehydes in good yield and with excellent diastereoselectivity and enantioselectivity. This desymmetrization process provides highly functionalized cyclobutanones with control over three contiguous stereogenic centers.

Journal: :Chemical communications 2009
Ivan A Shuklov Natalia V Dubrovina Enrico Barsch Ralf Ludwig Dirk Michalik Armin Börner

For the first time the hydrogen bond based structure of self-aggregated Rh-phosphine complexes in fluorinated alcohols was directly determined, which gives a rationale for the high enantioselectivity observed in the asymmetric hydrogenation.

Journal: :Chemical communications 2006
Christoforos G Kokotos Varinder K Aggarwal

Phenyl stabilised chiral sulfur ylides react with five-membered-ring hemiaminals to give functionalised pyrrolidines directly with high enantioselectivity. The reaction can be diverted to give piperidines instead by isolation of the intermediate epoxide and treatment with TMSOTf.

Journal: :Chemical communications 2011
Gaoxi Jiang Benjamin List

The first Ru-catalyzed enantioselective hydrovinylation has been realized by using an asymmetric counteranion-directed catalysis strategy. Styrene derivatives react with ethylene in excellent yields and promising enantioselectivity using this approach.

Journal: :Organic letters 2011
Yu Zhao Amir H Hoveyda Richard R Schrock

The utility of W-alkylidene complexes for enyne ring-closing metathesis is demonstrated in a direct comparison with Mo-based analogs. Tungsten complexes lead to less alkyne oligomerization and higher levels of endo-selectivity and enantioselectivity.

Journal: :Organic & biomolecular chemistry 2010
Liujuan Chen Sanzhong Luo Jiuyuan Li Xin Li Jin-Pei Cheng

Kinetic resolution of 6-aryl-2,6-hexanediones was achieved with chiral secondary amine catalyzed intramolecular aldolization. The current kinetic resolution protocol enables the synthesis of both enantiomers of cyclohexenones with moderate to good enantioselectivity.

Journal: :Chemical communications 2004
Panagiotis Manesiotis Andrew J Hall Marco Emgenbroich Milena Quaglia Ersilia De Lorenzi Börje Sellergren

Using 1-(4-styryl)-3-(3-nitrophenyl)urea as host monomer for the imprinting of Z-(D or L)-Glu, a polymeric receptor exhibiting strong enantioselectivity and a change in color intensity upon binding of the guest was obtained.

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