K2CO3-Mediated Intramolecular Oxa-Michael Cyclization of α,β-Unsaturated Ketoximes: Synthesis of Densely Arene-Substituted 2-Isoxazolines Bearing a Quaternary Center
A versatile palladium-catalyzedsynthesis of highly substituted α,β-unsaturated carbonyl compounds has been developed. In contrast to the known Heck-type coupling reaction of unsaturated carbonyl compounds with aryl halides, the present methodology allows the use of stable and readily available saturated carbonyl compounds as the alkene source. In addition, the reaction proceeds well with low catalyst
Direct Aroylation of Olefins through a Cobalt/Photoredox‐Catalyzed Decarboxylative and Dehydrogenative Coupling with α‐Oxo Acids
作者:Alex M. Davies、Rafael D. Hernandez、Jon A. Tunge
DOI:10.1002/chem.202202781
日期:2022.12.27
Visible light promotes decarboxylative Heck-like benzoylations of olefins. This process leverages the synergistic interaction of a photoredox catalyst with cobaloxime catalysts to form enones through decarboxylation and hydrogen evolution. Mechanistic studies reveal different rate-limiting steps, depending on electronics of the olefin.
SOCl<sub>2</sub>-Catalyzed Meyer–Schuster Rearrangement of 3°-Propargylic Alcohols: Synthesis of Densely Arene-Substituted Pyrazolines Bearing Quaternary Centers from α,β-Unsaturated Carbonyl Compounds and Arylhydrazines
作者:Ram Singh Jat、M. Bhanuchandra
DOI:10.1021/acs.joc.3c01387
日期:2023.9.15
Meyer–Schuster rearrangement of 3°-propargyl alcohol to the corresponding α,β-unsaturatedcarbonylcompoundsunder SOCl2 catalysis has been reported. Terminal and internal propargyl alcohols efficiently participated in the reaction. Furthermore, we have demonstrated the synthetic utility of conjugated carbonylcompounds to access densely arene-substituted pyrazolines bearing quaternary centers by reacting
作者:Saumya Verma、Vikram Singh、Jawahar L. Jat、Bhoopendra Tiwari
DOI:10.1021/acs.joc.3c02478
日期:2024.6.7
The Beckmann reaction is one of the most atom-economical methods for the preparation of amides from ketones. Unlike ketones, the multiple competing reactivities of enones as well as the requirement of demanding reaction conditions for in situ generation of oximes have severely impacted the application of this reaction for the preparation of α,β-unsaturated amides. Herein, we describe the first chemoselective
example of photocatalytic cross-coupling of alkenes with aldehydes by a single catalyst without an external photosensitizer and any additives. Irradiation of the aromatic aldehyde and cobaloxime catalyst results in the formation of an acyl radical, which undergoes radical addition with alkene or indole and subsequently β-H elimination to afford alkenyl ketone. The reaction features cheap and readily available