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
Novelbifunctionalchiralsquaramide–amine organocatalysts have been developed by rational combination of pyrrolidine and a cinchona alkaloid. The catalysts promoted the enantioselective Michael addition of both mono- and diketones to a broad range of nitroalkenes providing the corresponding products in moderate to high yields with excellent enantioselectivities and diastereoselectivities (up to 96%
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