Direct Access to Highly Enantioenriched α-Branched Acrylonitriles through a One-Pot Sequential Asymmetric Michael Addition/Retro-Dieckmann/Retro-Michael Fragmentation Cascade
摘要:
A highly enantioselective synthesis of alpha-branched acrylonitriles is reported featuring a one-pot sequential asymmetric Michael addition/retro-Dieckmann/retro-Michael fragmentation cascade. The method, which relies on a solid, bench-stable, and commercially available acrylonitrile surrogate, is practical, scalable, and highly versatile and provides a direct access to a wide range of enantioenriched nitrite-containing building blocks. Most importantly, the method offers a new tool to incorporate an acrylonitrile moiety in an asymmetric fashion.
Copper-Catalyzed Conjugate Additions of Alkylboranes to Imidazolyl α,β-Unsaturated Ketones: Formal Reductive Conjugate Addition of Terminal Alkenes
作者:Hirohisa Ohmiya、Mika Yoshida、Masaya Sawamura
DOI:10.1021/ol102819k
日期:2011.2.4
Conjugateaddition of alkylboron compounds (alkyl-9-BBN) to imidazol-2-yl α,β-unsaturated ketones proceeded in the presence of a catalytic amount (10 mol %) of CuCl, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes), and t-BuOK. The alkylboranes are available through alkene hydroboration, and thus the overall process represents a reductive conjugateaddition of alkenes to enone derivatives. A
Copper‐Catalyzed Asymmetric Conjugate Addition of Dimethylzinc to Acyl‐
<i>N</i>
‐methylimidazole Michael Acceptors: a Powerful Synthetic Platform
作者:Sammy Drissi‐Amraoui、Marie S. T. Morin、Christophe Crévisy、Olivier Baslé、Renata Marcia de Figueiredo、Marc Mauduit、Jean‐Marc Campagne
DOI:10.1002/anie.201506189
日期:2015.9.28
An efficient copper‐catalyzedenantioselectiveconjugateaddition of dimethylzinc to α,β‐ and α,β,γ,δ‐unsaturated 2‐acyl‐N‐methylimidazoles has been achieved using a chiral bidentate hydroxyalkyl‐NHC ligand. The reactions proceeded with both excellent regio‐ and enantioselectivity (14 examples, 87–95 % ee) to afford the desired 1,4‐adducts, which were easily transformed to the corresponding aldehydes