We report the (R)-3,3′-I 2 −BINOL−boron-complex-catalyzed asymmetric 1,3-dipolar cycloaddition of 2′-hydroxychalcones with N,N′-cyclic azomethine imines, providing the corresponding N,N′-bicyclic pyrazolidine derivatives with three contiguous tertiary stereocenters in high yields with excellent diastereo-and enantioselectivities (up to >99:1 diastereomeric ratio and >99% enantiomeric excess). This catalytic system exhibits advantages of mild reaction conditions, high efficiency, and broad substrate scopes.
We report herein the (R)-3,3′-Br2-BINOL-catalyzed enantioselective conjugate
addition of organic boronic
acids to β,γ-unsaturated α-ketoesters to generate
the corresponding Michael addition products in moderate to high yields
and with moderate to excellent enantioselectivities (up to 99% ee). This catalytic system features characteristics of mild
reaction conditions, high efficiency, and tolerance to alkenylboronic
acids and heteroarylboronic acids.
Asymmetric conjugate addition of organic boronic acids to dienones was successfully achieved by using chiral 3,3'-disubstituted-BINOLs or hydroxytetraphenylenes as the catalyst. A series of enantiopure bis-adducts were readily generated in...
Herein, we report the enantioselective conjugate addition of organic boronic acids to α,β-unsaturated 2-acyl imidazoles using (R)-3,3′-I 2 -BINOL as the catalyst. The catalytic system shows high efficiency and tolerance to alkenylboronic acids and heteroarylboronic acids. The corresponding Michael addition products were obtained in moderate to excellent yields and with moderate to excellent enantioselectivities (up to 97% ee). A gram-scale reaction was also conducted, and the desired product was obtained in high yield with no erosion in enantioselectivity. Finally, the synthetic utility of the methodology was demonstrated by transforming the 2-acyl imidazole moiety to the corresponding aldehyde, carboxylic acid, ester, and amide derivatives.
We report the (S)-2,15-Cl2-DHTP-catalyzed enantioselective conjugate addition of organic boronic acids to β-enaminones, providing the corresponding addition products in high yields and moderate to excellent enantioselectivities (up to 98% ee)....
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