Isomerization to linear ketones is a valuable transformation of 1,2-disubstituted cyclopropanols proceeding through radical intermediates. Despite simplicity of this reaction, the known protocol required stoichiometric amounts of both an oxidant and a reducing agent. In this article, we report a cata- [a]
The 2‐(neopentylsulfinyl)aniline directing group that promotes rapid palladium‐catalyzed C–H acetoxylation and alkenylation of arylacetamides has been developed. The acetoxylation reaches completion within only 40 min at 100 °C and leads to the bis‐functionalized products. Alternatively, the reaction can be carried out at room temperature, which is beneficial for sensitive substrates. For the alkenylation, we have developed a protocol in which easily available 1‐substituted cyclopropanols were employed as equivalents of vinyl ketones.
A one-step catalytic oxidant-free synthesis of unsaturated ketones from 1,2-disubstituted cyclopropanols is reported. Previously for this transformation, only two- and three-step protocols have been developed. The reaction proceeds under irradiation with visible light in the presence of catalytic amounts of both an acridinium photocatalyst and a cobaloxime complex. 2-Aryl-substituted cyclopropanols react giving α,β-unsaturated ketones, while dehydrogenative ring opening of 2-alkyl-substituted substrates affords mixtures of α,β- and β,γ-enones. The reaction starts with one-electron oxidation of a cyclopropanol to cyclopropyloxy radical, presumably, by the photoexcited acridinium catalyst. We also found that Co(dmgBF2)2(MeCN)2 complex under an air atmosphere and irradiation with blue LEDs or upon heating can serve as a hydroxycyclopropane oxidant.
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