نتایج جستجو برای: asymmetric catalyst

تعداد نتایج: 108514  

Journal: :Organic letters 2002
Stefan France Harald Wack Ahmed M Hafez Andrew E Taggi Daniel R Witsil Thomas Lectka

[reaction: see text]. We describe a superior procedure for the catalytic, asymmetric synthesis of beta-lactams using a bifunctional catalyst system consisting of a chiral nucleophile and an achiral Lewis acid.

Journal: :Chemical communications 2012
Takahiro Nishimura Akira Noishiki Tamio Hayashi

Asymmetric addition of arylboroxines to δ-aryl-α,β,γ,δ-unsaturated ketones proceeded in the presence of an iridium catalyst coordinated with a chiral diene ligand to give high yields of δ-diaryl ketones with very high enantioselectivity.

Journal: :Chemical communications 2007
Francesca Gini Bart Hessen Ben L Feringa Adriaan J Minnaard

The complex formed from Pd(CH(3)CN)(4)(BF(4))(2) and (R,R)-MeDUPHOS is a highly enantioselective catalyst for the asymmetric conjugate addition of aryltriethylsiloxanes to a variety of unsaturated ketones, lactones and lactams.

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.

2008
Chun-Sheng Ling Qiang Wu Shan-Shan Li

In the title compound, C(17)H(19)NO(6), which may serve as a ketone catalyst for the asymmetric epoxidation of olefins, the crystal packing is consolidated by C-H⋯O inter-actions.

Journal: :Organic letters 2005
Qian Dai Weiran Yang Xumu Zhang

[reaction: see text] N-Aryl beta-amino esters were obtained by asymmetric hydrogenation of a new class of N-aryl beta-enamino esters. High conversions and up to 96.3% ee values were achieved with a Rh-TangPhos catalyst.

Journal: :Chemical communications 2009
Yi Li Xue-Qiang Wang Chao Zheng Shu-Li You

Camphor-derived chiral triazolium salts have been found to be highly efficient for asymmetric intramolecular Michael reactions. With 1-5 mol% of the catalyst, the desired products were obtained in excellent yields, with up to 99% ee.

Journal: :Chemical communications 2010
Takahiro Nishimura Takahiro Sawano Sumito Tokuji Tamio Hayashi

Asymmetric addition of (triisopropylsilyl)acetylene to nitroalkenes took place in the presence of a rhodium/chiral bisphosphine catalyst to give beta-alkynylated nitroalkanes in high yields with high enantioselectivity.

Journal: :Chemical communications 2011
Magnus Rueping René M Koenigs

A Brønsted acid differentiated metal catalyzed hydrogenation has been developed. A combinatorial variation of chiral triflylamides with achiral metal complexes results in a highly active catalyst for the asymmetric reduction.

Journal: :Organic & biomolecular chemistry 2016
Jian-Qiang Zhao Deng-Feng Yue Xiao-Mei Zhang Xiao-Ying Xu Wei-Cheng Yuan

The asymmetric Neber reaction of 3-O-sulfonyl ketoxime, in situ generated from isatin ketoxime and sulfonyl chloride, for the synthesis of chiral spirocyclic oxindole compounds is reported. With the developed protocol, a range of chiral spirooxindole 2H-azirines could be obtained in good to excellent yields and up to a 92 : 8 enantiomeric ratio by using (DHQD)2PHAL as the catalyst. This methodo...

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