Readily Accessible 9-epi-amino Cinchona Alkaloid Derivatives Promote Efficient, Highly Enantioselective Additions of Aldehydes and Ketones to Nitroolefins
作者:Séamus H. McCooey、Stephen J. Connon
DOI:10.1021/ol0628006
日期:2007.2.1
from commercially available starting materials, have been shown to promote highly enantio- and diastereoselective Michael-type addition reactions between enolizable carbonyl compounds and nitroalkenes of broad scope. The influence of both the absolute and relative stereochemistry at C-9 on catalyst performance has also been assessed. [reaction: see text].
Asymmetric Michael addition reactions of aldehydes with nitrostyrenes catalyzed by functionalized chiral ionic liquids
作者:Qianying Zhang、Bukuo Ni、Allan D. Headley
DOI:10.1016/j.tet.2008.03.073
日期:2008.5
A new class of pyrrolidine-based functionalized chiralionicliquids (FCILs) has been developed and shown to be effective and reusable catalysts for the asymmetricMichaeladditionreactions. For the Michaeladditionreaction involving various aldehydes and nitrostyrenes, FCIL 6, in combination with trifluoroacetic acid as an additive, was found to be a very effective catalyst, compared to FCIL 3,
Organocatalytic Direct Michael Reaction of Ketones and Aldehydes with β-Nitrostyrene in Brine
作者:Nobuyuki Mase、Kaori Watanabe、Hidemi Yoda、Kunihiko Takabe、Fujie Tanaka、Carlos F. Barbas
DOI:10.1021/ja060338e
日期:2006.4.1
We have developed a direct, asymmetric Michael reaction that can be performed in brine or seawater without addition of organic solvents. A bifunctional catalyst with long hydrophobic alkyl chains efficiently catalyzed Michael reactions and afforded the desired products in excellent yield with high enantiomeric excess, even when only an equal molar ratio of the donor to acceptor was used.
Direct Asymmetric Organocatalytic Michael Reactions of α,α-Disubstituted Aldehydes with β-Nitrostyrenes for the Synthesis of Quaternary Carbon-Containing Products
作者:Nobuyuki Mase、Rajeswari Thayumanavan、Fujie Tanaka、Carlos F. Barbas
DOI:10.1021/ol049196o
日期:2004.7.1
Direct asymmetric catalytic Michael reactions have been performed using chiral-amine/acid bifunctional catalysts. Performed with 0.3 equiv of (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine and 0.3 equiv of trifluoroacetic acid as the catalyst, the reaction of alpha,alpha-dialkylaldehydes with (E)-beta-nitrostyrene provided the alpha,alpha-dialkyl Michael products in up to 96% yield with up to 91% ee. With respect to enantioselectivity, L-proline was a poor catalyst of this class of Michael reactions.
Solid Supported 9-Amino-9-deoxy-<i>epi</i>-quinine as Efficient Organocatalyst for Stereoselective Reactions in Batch and Under Continuous Flow Conditions
AbstractPolystyrene‐supported 9‐amino‐9‐deoxy‐epi‐quinine was synthesized through co‐polymerization of an ad hoc‐designed chiral monomer with divinylbenzene, in the presence of azobis(isobutyronitile) (AIBN) as radical initiator and toluene and 1‐dodecanol as porogenic solvents. The heterogenized catalyst efficiently promoted the reaction of isobutyric aldehyde with β‐nitrostyrene, in very high yield and enantioselectivity, comparable or even higher than that of the homogeneous counterpart (up to 95% ee). The recyclability of the catalyst, its general applicability and its successful application to other reactions was also demonstrated. Finally, for the first time, a 9‐amino‐epi‐quinine derivative was employed to perform an enantioselective Michael reaction under continuous‐flow conditions; by using a home‐made, packed‐bed catalytic reactor, the aldehyde addition to nitrostyrene was successfully realized in flow mode, leading to the product in up to 93% ee.magnified image