Origin of the Enantioselectivity in Organocatalytic Michael Additions of β-Ketoamides to α,β-Unsaturated Carbonyls: A Combined Experimental, Spectroscopic and Theoretical Study
作者:Adrien Quintard、Diana Cheshmedzhieva、Maria del Mar Sanchez Duque、Anouk Gaudel-Siri、Jean-Valère Naubron、Yves Génisson、Jean-Christophe Plaquevent、Xavier Bugaut、Jean Rodriguez、Thierry Constantieux
DOI:10.1002/chem.201404481
日期:2015.1.7
The organocatalytic enantioselective conjugate addition of secondary β‐ketoamides to α,β‐unsaturated carbonyl compounds is reported. Use of bifunctional Takemoto’s thiourea catalyst allows enantiocontrol of the reaction leading either to simple Michael adducts or spirocyclic aminals in up to 99 % ee. The origin of the enantioselectivity has been rationalised based on combined DFT calculations and kinetic
Asymmetric α-Photoalkylation of β-Ketocarbonyls by Primary Amine Catalysis: Facile Access to Acyclic All-Carbon Quaternary Stereocenters
作者:Yunbo Zhu、Long Zhang、Sanzhong Luo
DOI:10.1021/ja508605a
日期:2014.10.22
We describe the direct construction of all-carbon quaternarystereocentersvia α-photoalkylation of β-ketocarbonyls with high efficacy and enantioselectivities by merging photoredoxcatalysis and primaryaminecatalysis. The open-shell photoradical approach enables asymmetric α-alkylations that are difficult under thermal conditions.
Visible Light Promoted β-C-H Alkylation of β-Ketocarbonyls <i>via</i>
a β-Enaminyl Radical Intermediate
作者:Dehong Wang、Long Zhang、Sanzhong Luo
DOI:10.1002/cjoc.201700785
日期:2018.4
carbonyl activation mode is reported on the basis of photo‐induced single‐electron‐transfer (SET) oxidation of a secondary enamine. The resultant β‐enaminyl radical intermediate was trapped by a wide range of Michael acceptors, producing β‐alkylation products of β‐ketocarbonyls in a highly efficient manner.
Highly Diastereo- and Enantioselective Synthesis of α-Spiro-δ-lactams by an Organocascade Reaction
作者:Kaiheng Zhang、Marta Meazza、Vojtěch Dočekal、Mark E. Light、Jan Veselý、Ramon Rios
DOI:10.1002/ejoc.201700193
日期:2017.4.3
An asymmetric synthesis of α-spiro-δ-lactam via organocascade reaction from easily accessible starting materials is reported. The catalytic sequence undergoes enantioselective Michael addition of β-ketoamide to α,β-unsaturated aldehyde catalysed by a secondary amine catalyst, followed by hemiaminal annulation. Optically enantiopure compounds with two contiguous stereogenic centres are obtained in good
报道了通过有机级联反应从容易获得的起始材料不对称合成 α-螺-δ-内酰胺。催化序列在仲胺催化剂的催化下,对 β-酮酰胺与 α,β-不饱和醛进行对映选择性迈克尔加成,然后进行半胺化环化。以良好的产率和出色的选择性(高达 >20:1 dr 和高达 >99% ee)获得具有两个连续立体中心的光学对映体纯化合物。
Control of Activation Mode To Achieve Diastereodivergence in Asymmetric Syntheses of Chiral Spiropiperidinone Derivatives
作者:Xiang Li、Wei Huang、Yan-Qing Liu、Jing-Wen Kang、Dan Xia、Gu He、Cheng Peng、Bo Han
DOI:10.1021/acs.joc.6b02489
日期:2017.1.6
efficient organocatalytic cascadereaction has been developed involving a Michael–hemiaminalization relay for the asymmetric synthesis of spiropiperidinone derivatives bearing adjacent quaternary and tertiary chiral centers via LUMO or HOMO activation. Importantly, this methodology demonstrates that applying distinct activation modes to different substrates in the same reaction can diverge diastereoselectivity