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
Construction of Complex 1,3-Cyclohexadienes via Phosphine-Catalyzed (4 + 2) Annulations of δ-Acetoxy Allenoates and Ketones
作者:Yuwen Zhang、Xiaofeng Tong
DOI:10.1021/acs.orglett.7b02787
日期:2017.10.6
The phosphine-catalyzed substrate-dependent (4 + 2) annulations of δ-acetoxy allenoates with ketones is described. Allenoates 1 with an alkyl substituent at δC are able to react with cyclic 1,3-diketones 2, wherein the δC is attacked by the methenyl carbon of 2 while the αC attacks the ketone of 2. Allenoates 5 with an aryl group at δC is poised to react with cyclic β-carbonyl amides 6, in which the
A Cooperative Participation of the Amido Group in the Organocatalytic Construction of All-Carbon Quaternary Stereocenters by Michael Addition with β-Ketoamides
作者:Maria del Mar Sanchez Duque、Olivier Baslé、Nicolas Isambert、Anouk Gaudel-Siri、Yves Génisson、Jean-Christophe Plaquevent、Jean Rodriguez、Thierry Constantieux
DOI:10.1021/ol200924e
日期:2011.7.1
The secondary amido group of a-substituted beta-ketoamides plays a crucial role in the control of the reactivity and spatial arrangement (selectivity) in the organocatalyzed Michael addition to unsaturated carbonyls. This results in an unprecedented activation mode of substrates through H-bonding interactions allowing the construction of enantiomerically enriched functionalized all-carbon quaternary centers and spiroaminals of high synthetic potential.
Activation of 1,2- and 1,3-Ketoamides with Thiourea Organocatalyst for the Enantioselective Domino Synthesis of Functionalized Cyclohexanes
Several reactive sites of 1,2- and 1,3-ketoamides were successively exploited in two complementary domino transformations for the synthesis of polysubstituted monocyclic or bridged bicyclic cyclohexanes, with the creation of up to six stereogenic centers. In both cases, a chiral bifunctional thiourea organocatalyst allowed efficient control of chirality in the final carbocycle.