K2CO3-Mediated Intramolecular Oxa-Michael Cyclization of α,β-Unsaturated Ketoximes: Synthesis of Densely Arene-Substituted 2-Isoxazolines Bearing a Quaternary Center
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
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
Friedel-Crafts-type acylation of alkenes with acyl chlorides has been successfully conducted with a wide substrate scope by the combined use of AlCl3 and 2,6-dibromopyridine. Trisubstituted alkenes afford allylketones or vinylketones depending on the presence or absence of hydrogen atom(s) at the beta-position to the acylation site, while monosubstituted alkenes exclusively afford vinylketones.
Meyer,K. H.; Schuster, Chemische Berichte, 1922, vol. 55, p. 817