نتایج جستجو برای: asymmetric catalyst
تعداد نتایج: 108514 فیلتر نتایج به سال:
Asymmetric addition of arylboronates to aryl-substituted cyclic ketimines proceeded in the presence of a rhodium catalyst coordinated with a chiral diene ligand to give high yields of sulfamidates and sulfamides with high enantioselectivity (up to 99% ee).
This paper describes an efficient asymmetric biomimetic transamination of α-keto esters with a quinine-derived chiral base as the catalyst, giving a variety of β-branched α-amino esters in 50-96% yield and 87-95% ee.
[reaction: see text]. A novel catalytic system for asymmetric hydrogenation of functionalized ketones has been developed using a Pd/bisphosphine complex as the catalyst in 2,2,2-trifluoroethanol. The reaction exhibits high enantioselectivity, and up to 92.2% ee was obtained.
Transition metals can catalyse the stereoselective synthesis of cyclic organic molecules in a highly atom-efficient process called cycloisomerization. Many diastereoselective (substrate stereocontrol), and enantioselective (catalyst stereocontrol) cycloisomerizations have been developed. However, asymmetric cycloisomerizations where a chiral catalyst specifies the stereochemical outcome of the ...
An efficient, classical resolution of the versatile P-ligand intermediate 6-phospha-2,4,8-trioxa-adamantane (CgPH) is described and the rhodium complex of the optically pure secondary phosphine beta-CgPH is an active and moderately selective asymmetric hydrogenation catalyst.
A series of iron complexes of chiral iminopyridine-oxazoline (IPO) ligands have been synthesized. The most sterically hindered iron catalyst exhibits excellent activity (up to 99% yield) and high enantioselectivity (up to 93% ee) in asymmetric hydrosilylation of aryl ketones.
Amides with quaternary stereogenic centers have been synthesised by catalytic asymmetric vinylogous Mukaiyama aldol reactions. The chiral copper-sulfoximine catalyst gives rise to products with moderate to good yields and up to 92% ee.
trans-1,2-Diaminocyclohexane functionalized mesoporous silica was applied as an ideal catalyst for asymmetric Michael addition of various nitroalkane derivatives. Short channels and plugs in the pore structure offered chiral enhancement in Michael addition.
The catalytic asymmetric 1,2-addition of a series of arylboronic acids to 2,2,2-trifluoroacetophenones is described with high isolated yields (up to 96%) and good enantioselectivities (up to 83% ee) using a rhodium(I)/phosphoramidite catalyst.
Organocatalysts for the asymmetric reduction of ketimines are presented that function well at low catalyst loadings providing chiral amines in good yield and enantioselectivity, the latter appearing to be independent of the ketimine substrate geometry.
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