An unexpected Cu-catalyzed deoxygenative C2-sulfonylation reaction of quinoline N-oxides in the presence of radical initiator K2S2O8 was developed that used sodium sulfinate as a sulfonyl coupling partner. The mechanism studies indicate that the reaction proceeds via Minisci-like radical coupling step to give sulfonylated quinoline with good chemical yields.
A palladium-catalyzed ortho-halogenation (I, Br, Cl) of arylnitrile is described. The optimal reaction conditions were identified after examining various factors such as catalyst, additive, solvent, and reaction temperature. Using cyano as the directing group, the halogenation reaction gave good to excellent yields. The method is compatible to the arylnitriles with either electron-withdrawing or electron-donating groups. The reaction is available to the substrate in at least gram scale. The present method was successfully applied to the synthesis of the precursors of paucifloral F and isopaucifloral F.
A NiH-catalyzed thioether-directed
cyclometalation strategy is
developed to enable remote methylene C–H bond amidation of
unactivated alkenes. Due to the preference for five-membered nickelacycle
formation, the chain-walking isomerization initiated by the NiH insertion
to an alkene can be terminated at the γ-methylene site remote
from the alkene moiety. By employing 2,9-dibutyl-1,10-phenanthroline
(L4) as the ligand and dioxazolones as the reagent, the
amidation occurs at the γ-C(sp3)–H bonds to
afford the amide products in up to 90% yield (>40 examples) with
remarkable
regioselectivity (up to 24:1 rr).
A new protocol for C-S and C-Se bond formation by the direct functionalization of the C(sp(3))-H bond of alkanes under metal-free conditions was developed. Using (t)BuOO(t)Bu as the oxidant, the reaction of disulfides or diselenides with alkanes gave sulfides or selenides in moderate to good yields. The method was very simple and atom-economical.
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