Novel thiourea-amine bifunctional catalysts for asymmetric conjugate addition of ketones/aldehydes to nitroalkenes: rational structural combination for high catalytic efficiency
A series of thiourea-amine bifunctionalcatalysts have been developed by a rational combination of prolines with cinchona alkaloids, which are connected by a thiourea motif. The catalyst 3a, prepared from L-proline and cinchonidine, was found to be a highly efficient catalyst for the conjugateaddition of ketones/aldehydes to a wide range of nitroalkenes (up to 98/2 dr and 96% ee). The privileged cinchonidine
CINCHONA-BASED BIFUNCTIONAL ORGANOCATALYSTS AND METHOD FOR PREPARING CHIRAL HEMIESTERS USING THE SAME
申请人:SONG Choong Eui
公开号:US20110213151A1
公开(公告)日:2011-09-01
The present invention relates to cinchona-based bifunctional organocatalysts and methods for preparing chiral hemiesters using the same. More specifically, the present invention relates to methods for preparing chiral hemiesters from prochiral or meso cyclic acid anhydrides via desymmetrization, using bifunctional cinchona alkaloid catalysts comprising sulfonamide functional groups.
Squaramide-catalysed asymmetric Friedel–Crafts alkylation of naphthol and unsaturated pyrazolones
作者:Ran Wei、Li Gao、Gaihui Li、Li Tang、Guoshun Zhang、Feilang Zheng、Heng Song、Qingshan Li、Shurong Ban
DOI:10.1039/d1ob00347j
日期:——
The first method for highly efficient asymmetric Michael-type Friedel–Craftsalkylation of naphthol and unsaturated pyrazolones has been accomplished under mild reaction conditions. In the presence of the chiral squaramide catalyst, a wide range of substrates are tolerated in excellent yields (up to 99%) with reasonable enantioselectivities (up to 96% ee).
在温和的反应条件下完成了萘酚和不饱和吡唑啉酮类高效不对称 Michael 型 Friedel-Crafts 烷基化的第一种方法。在手性方酸酰胺催化剂的存在下,可以以优异的收率(高达 99%)和合理的对映选择性(高达 96% ee)耐受各种底物。
Promotion of Henry reactions using Cu(OTf)2 and a sterically hindered Schiff base: access to enantioenriched β-hydroxynitroalkanes
The steric and electronic properties of chiral Schiff base ligands derived from cinchona alkaloids were evaluated in asymmetric Henry reactions. Amongst these, the stericallyhindered ligand 2 showed outstanding catalytic efficiency in the Cu(II) catalyzed asymmetric addition of nitroalkanes to a variety of aldehydes to afford the desired adducts in high yields (up to 97%) with excellent enantioselectivities
The organocatalytic enantioselective decarboxylative addition of malonic acid half thioesters to ketimines derived from isatins by using N‐heteroarenesulfonyl cinchonaalkaloid amides afforded products with high enantioselectivity. The products could be converted into optically active AG‐041R. X‐ray crystallographic analysis revealed that the hydrogen bonding between the sulfonimide proton and the