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
4-Aminothioureaprolinal dithioacetal 4a is a highlyefficientcatalyst for the asymmetric Michaeladdition of ketones and aldehydes to nitroolefins requiring only 3 mol-% catalyst loading. The reactions proceeded smoothly and gave syn selective adducts with excellent yields (up to 98 % yield), diastereoselectivity (up to >99:1 dr), and enantioselectivity (up to 99 % ee) under solvent free conditions
Enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes catalyzed by binaphthyl-derived organocatalysts
作者:Saet Byeol Woo、Dae Young Kim
DOI:10.3762/bjoc.8.78
日期:——
The highly enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes, promoted by binaphthyl-modified chiral bifunctional organocatalysts is described. This reaction afforded the chiral functionalized naphthoquinones in high yields (81-95%) and excellent enantioselectivities (91-98% ee) under low catalyst loading (1 mol %).
Enantioselective Conjugate Addition of Both Aromatic Ketones and Acetone to Nitroolefins Catalyzed by Chiral Primary Amines Bearing Multiple Hydrogen-Bonding Donors
of chiral primary amine catalysts bearing multiple hydrogen-bonding donors have been designed and synthesized. The newly developed bifunctional organocatalysts efficiently catalyzed not only enantioselectiveconjugateaddition of aromatic ketones to nitroolefins in good yields (up to 87%) with excellent enantioselectivities (97→99% ee) but also enantioselectiveconjugateaddition of acetone to nitroolefins
Asymmetric domino aza-Michael–Michael reaction of o-N-protected aminophenyl α,β-unsaturated ketones: construction of chiral functionalized tetrahydroquinolines
作者:Shinae Kim、Ki-Tae Kang、Sung-Gon Kim
DOI:10.1016/j.tet.2014.05.114
日期:2014.8
The diastereo- and enantioselective synthesis of 2,3,4-trisubstitutedtetrahydroquinolines has been developed through organocatalytic domino aza-Michael–Michaelreaction of o-N-tosylaminophenyl α,β-unsaturated ketones with nitroalkenes. This useful and simple domino process afforded diverse highly functionalized tetrahydroquinolines, some of which are not easily accessible using other methodologies