We report a C(sp3)−C(sp3) cross‐coupling of alkyl bromides and alkyl chlorides with ethers by dual photoredox‐nickel catalysis. The catalytic system comprises of the organic photocatalyst 1,2,3,5‐tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene (4‐CzIPN) and bench stable nickel (II) acetylacetonate in the presence of visible‐light, providing the coupling products in up to 92% yield. Preliminary mechanistic studies suggest two catalytic cycles, as well as the photogeneration of bromine or chlorine radicals from halide atoms that are present in the structures of the coupling partners. The halide radical mediates the hydrogen atom transfer event, avoiding the need of an additional HAT catalyst.
Aromatic heterocycles are omnipresent structural motifs in various natural products, pharmaceuticals and agrochemicals. This work describes ap hotocatalytic Miniscitype CÀHf unctionalization of heteroarenes with non-activated alkyl bromides. The reaction avoids stoichiometricr adical-promoters, oxidants, or acids, and is conducted using blue LEDs as the light source.T he reactive carbon-centered alkyl radicals are generated by merging the photoredox approachw ith bromidea nion co-catalysis and spatialp re-aggregation of reacting speciesi nt he micellara queous solutions.T he obtained data highlight the critical importance of microstructuring and organization of the components in the reactionmixture. Scheme1.Strategies for CÀHa lkylation of heteroarenes with non-activated alkyl bromides. SDS-sodium dodecyl sulfate.
A radical
cascade process initiated through visible-light induced thiyl radical
coupling with ortho-substituted arylisocianides followed
by an intramolecular cyclization and subsequent aromatization to access
2-sulfenylindoles is described. The key thiyl radicals are promptly
generated via a hydrogen atom transfer event. The redox-neutral protocol
features broad substrate scope, excellent functional group tolerance,
and mild reaction conditions. Furthermore, the implementation of a
continuous flow variant allows smooth scalability with a short residence
time through process intensification.
We disclose herein a simple and direct method to synthesize vicinal tricarbonyl compounds (VTC) from Morita-Baylis-Hillman (MBH) adducts. The method is based on two sequential oxidation steps which provide VTC in moderate to good yields. This is the first report of the synthesis of vicinal tricarbonyl compounds from MBH adducts.
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