نتایج جستجو برای: asymmetric catalyst
تعداد نتایج: 108514 فیلتر نتایج به سال:
[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.
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.
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.
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.
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.
[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.
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.
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.
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.
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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