Asymmetric Michael Addition Induced by the Anion of an Imidazolium Salt
作者:Vincent Gauchot、Julien Gravel、Andreea R. Schmitzer
DOI:10.1002/ejoc.201201068
日期:2012.11
We describe the application of a chiral catalytic imidazoliumsalt derived from trans-L-hydroxyproline, the anion being the catalytic entity, as a catalyst for the asymmetricMichaeladdition. We report the first example of a catalytic Michaeladdition using this type of catalyst, leading to excellent yields (up to 99 %) and good selectivities (up to 99:1 dr, up to 82 % ee).
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].
Remarkable Effect of
<i>tert</i>
‐Amine Additives in the Asymmetric Direct Michael Reaction of Ketones with β‐Arylnitroethenes Catalyzed by an
<i>L</i>
‐Hydroxyproline‐Based Amino Tf‐Amide Organocatalyst
A catalytic asymmetric direct Michaelreaction of ketones with trans‐β‐arylnitroethenes has been developed by using optically pure L‐hydroxyproline‐based secondary‐amino aromatic Tf‐amide organocatalyst. The effect of diethylmethylamine base additive is of crucial importance to accelerate the reaction and also to achieve high enantioselectivity.
Silica gel supported pyrrolidine-based chiral ionic liquid as recyclable organocatalyst for asymmetric Michael addition to nitrostyrenes
作者:Pinhua Li、Lei Wang、Yicheng Zhang、Guanwu Wang
DOI:10.1016/j.tet.2008.05.039
日期:2008.8
silica gel supported pyrrolidine-basedchiralionicliquid 6a has been developed and found to be a highly effective catalyst for the Michaeladditionreaction of ketones with nitrostyrenes. The reactions generated the corresponding products in good yields (up to 94%), excellent enantioselectivities (up to >99% ee), and high diastereoselectivities (up to >99:1 dr). In addition, the catalyst 6a can be
The direct smallpeptide-catalyzedenantioselective Michael addition of ketones to nitroolefins is presented. Simple di- and tripeptides derived from alanine catalyze the asymmetric Michael additions with high stereoselectivity and furnish the corresponding Michael products in high yield with up to 68 : 1 dr and 98% ee. The study demonstrates that small, readily prepared peptides with increased structural