Cobalt(iii)-catalyzed redox-neutral [4+2]-annulation ofN-chlorobenzamides/acrylamides with alkylidenecyclopropanes at room temperature
An efficient synthesis of substituted 3,4-dihydroisoquinolinones through [4+2]-annulation ofN-chlorobenzamides/acrylamides having a monodentate directing group with alkylidenecyclopropanes in the presence of a less expensive, highly abundant and air stable Co(iii) catalystviaa C-H activation is demonstrated. In this reaction, the N-Cl bond ofN-chlorobenzamide serves as an internal oxidant and thus an external metal oxidant is avoided. The 3,4-dihydroisoquinolinone derivatives are converted successfully into the highly useful imidoyl chloride derivatives. The deuterium labeling and kinetic isolabelling studies reveal that the C-H activation is a rate-determining step in this cyclization reaction.
Ramesh, Balu,Jeganmohan, Masilamani
supporting information
p. 3692 - 3695
(2021/04/16)
Gem-Difluorination of Methylenecyclopropanes (MCPs) Featuring a Wagner-Meerwein Rearrangement: Synthesis of 2-Arylsubstituted gem-Difluorocyclobutanes
The geminal difluorocyclobutane core is a valuable structural element in medicinal chemistry. Strategies for gem-difluorocyclobutanes, especially the 2-substituted cases, are limiting and often suffer from harsh reaction conditions. Reported herein is a m
Nickel-Catalyzed Favorskii-Type Rearrangement of Cyclobutanone Oxime Esters to Cyclopropanecarbonitriles
A nickel-catalyzed base-promoted rearrangement of cyclobutanone oxime esters to cyclopropanecarbonitriles was developed. The ring opening of cyclobutanone oxime esters occurs at the sterically less hindered side. A base-promoted nickelacyclobutane intermediate, formed in situ, is assumed to be involved in the formation of the product.
Fang, Ping,Mei, Tian-Sheng,Shuai, Bin
supporting information
p. 1637 - 1641
(2021/10/02)
Rhodium-Catalyzed Ring-Opening Hydroacylation of Alkylidenecyclopropanes with Chelating Aldehydes for the Synthesis of γ,δ-Unsaturated Ketones
The first intermolecular ring-opening hydroacylation of alkylidenecyclopropanes with chelating aldehydes through a rhodium-catalyzed acrylamide-promoted protocol is reported. This highly efficient catalytic system enables the direct synthesis of a diverse
Ring opening of methylenecyclopropanes with halides in liquid sulfur dioxide
Methylenecyclopropanes (MCP) undergo ring opening reactions with group I and II metal halides and ammonium halides in liquid SO2 to afford homoallylic halides, which are versatile reagents in organic synthesis. The developed reaction conditions are compatible with acid-labile substrates such as N-Boc-protected compounds. Liquid SO2 is a polar reaction medium with Lewis acid properties that solubilizes inorganic salts. The unique properties of SO2 were demonstrated by control experiments: 1) upon performing the reactions with the aforementioned salts in conventional solvents, the MCP ring opening was not observed either in the presence of catalytic amounts of H3PO4 (similar pKa to that of H2SO3), or in the absence of H3PO4; 2) a solution of SO2 in THF exhibited similar properties to that of liquid SO2.
Le?kovskis, Kristaps,Gulbe, Krista,Mishnev, Anatoly,Turks, Māris
supporting information
(2020/10/19)
Enantioselective Radical Ring-Opening Cyanation of Oxime Esters by Dual Photoredox and Copper Catalysis
Catalytic enantioselective chemical reactions involving highly reactive radical species remain largely unexplored. We report herein for the first time a novel enantioselective radical ring-opening cyanation of redox-active oxime esters by dual photoreodox
Organoselenium-Catalyzed Oxidative Ring Expansion of Methylenecyclopropanes with Hydrogen Peroxide
Catalyst screening and optimization of reaction conditions allowed control of the organoselenium-catalyzed oxidative ring expansion of highly active methylenecyclopropanes to give substituted cyclobutanones selectively. This protocol employs H2O2 as a clean oxidant and generates no waste and, therefore, provides green access to useful, but not readily available, substituted cyclobutanones under mild conditions.
Yu, Lei,Chen, Fenglin,Ding, Yuanhua
p. 1033 - 1037
(2016/04/05)
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