Asymmetric Hydrogenation of α,α′-Disubstituted Cycloketones through Dynamic Kinetic Resolution: An Efficient Construction of Chiral Diols with Three Contiguous Stereocenters
Chiral diols with threecontiguousstereocenters were synthesized by a highly enantioselective ruthenium‐catalyzedasymmetric hydrogenation of racemic α,α′‐disubstituted cycloketones involving dynamic kineticresolution. This new catalytic asymmetric method provides a concise route to the alkaloid (+)‐γ‐lycorane.
The first palladium-catalyzedasymmetric allylic trifluoromethylation is disclosed. The methodology evokes a fundamental principle by which the synergistic interplay of a leaving group and its subsequent activation of the nucleophilic trifluoromethyl group enabled the reaction. Allyl fluorides have been shown to be superior precursors for generation of π-allyl complexes, which lead to trifluoromethylated
Direct Regioselective Dehydrogenation of α‐Substituted Cyclic Ketones
作者:Sebastian Armin Schwengers、Gabriela Guillermina Gerosa、Tynchtyk Amatov、Naoki Yasukawa、Sebastian Brunen、Markus Leutzsch、Benjamin Mitschke、Grigory André Shevchenko、Benjamin List
DOI:10.1002/anie.202307081
日期:2023.8.28
A highly regioselective, one-step dehydrogenation of α-substituted cyclicketones in the presence of 2,3-dichlorobenzo-5,6-dicyano-1,4-benzoquinone is described. The reaction proceeds via phosphoric acid-based enol catalysis and provides access to several α-aryl and α-alkyl substituted α,β-unsaturated ketones.
Practical and Efficient Suzuki−Miyaura Cross-Coupling of 2-Iodocycloenones with Arylboronic Acids Catalyzed by Recyclable Pd(0)/C
作者:François-Xavier Felpin
DOI:10.1021/jo051501b
日期:2005.10.1
The first Suzuki-Miyaura cross-coupling of 2-iodocycloenones with arylboronic acids catalyzed by 10% Pd(O)/C is described as an interesting alternative to classical homogeneous conditions. Most of the substrate reacted under mild condition at 25 degrees C under air in aqueous DME. The conditions described tolerate a wide range of iodoenones and boronic acids. Notably, the procedure features inexpensive reagents and solvents with low toxicity rendering the method environmentally benign. Additionally 10% Pd(O)/C could be recovered and efficiently reused at least five times without significant alteration of the yields of the cross-coupled product.
Ring Enlargements. V. The Preparation of 2-Arylcycloheptanones and 2-Aryl-2-cycloheptenones<sup>1</sup>