K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>-Mediated Selective Trifluoromethylacylation and Trifluoromethylarylation of Alkenes under Transition-Metal-Free Conditions: Synthetic Scope and Mechanistic Studies
on and -arylation of alkenes with inexpensive CF3SO2Na and K2S2O8 in aqueous media has been developed, respectively, affording the highly chemoselective synthesis of CF3-functionalized chroman-4-ones and chromanes in satisfactory yields. Control experiments and DFT calculations indicate that the CF3SO2Na/K2S2O8 system is capable of trifluoromethylating the substrate of alkenes without a transition
2-(3-Aryl-2-propenyloxy)benzaldehyde (or 1-naphthaldehyde) arylhydrazones undergo an intramolecular cycloaddition reaction via their 1,3-dipolar tautomers, azomethine imines, to the alkenyl group. Initial cycloadducts were converted to dehydrogenated compounds under the reaction conditions. On the other hand, introduction of cyano or ethoxycarbonyl groups instead of the aryl group into 3-position of
A cascade process for the synthesis of <i>ortho</i>-formyl allyl aryl ethers and 2<i>H</i>-chromen-2-ol derivatives from arynes <i>via</i> trapping of <i>o</i>-quinone methide with an activated alkene
作者:Abhilash Sharma、Pranjal Gogoi
DOI:10.1039/c8ob02507j
日期:——
A transition-metal free synthetic strategy has been developed for the direct synthesis of ortho-formyl substituted allyl aryl ethers via a cascade three-component coupling of arynes, activated alkene and N,N-dimethylformamide. The reaction proceeds via C–O and C–Cbond cleavage as well as C–C and two new C–Obond formations in a single reaction vessel. The methodology provides a good yield of ortho-formyl
“Diazo” not needed: The title reaction results in the rearrangement of oxonium ylides, which were prepared from readily available homopropargylic allylic ethers instead of diazo compounds, through two different mechanisms: a concerted 2,3‐sigmatropic rearrangement, or a stepwise 1,4‐allyl migration followed by a Claisen rearrangement (see scheme).