An efficient synthesis of cyanoalkylated heteroarenes via iron-catalyzed direct C-H cyanoalkylation of heteroarenes has been developed. Structurally diverse cyanoalkyl motifs generated through C-C bond cleavage of cyclobutanone oxime esters have been introduced into quinoxalin-2(1H)-ones, flavone, benzothiazoles, and caffeine in good to excellent yields. Remarkably, less-strained cyclopentanone and unstrained cyclohexanone oxime esters were also amenable substrates in this cyanoalkylation reaction.
A direct C-H cyanoalkylation of heteroaromatic N-oxides and quinones with cyclobutanone oximes is reported. This redox-neutral, operationally simple cyanoalkylation reaction is successfully amenable to a wide range of heteroaromatic N-oxides, quinones, and cyclobutanone oximes. A novel catalytic system consisting of a nickel source proved crucial for cleavage of the C-C bond of cyclobutanone oximes and for selective C-C bond formation over β-hydride elimination. Mechanistic studies suggest that a radical intermediate might be involved in this transformation.
An efficient iron-catalyzed intermolecular
remote C(sp3)–H heteroarylation of alkyl ketones
has been developed via
an iminyl radical-triggered 1,5-hydrogen-atom transfer (HAT) cascade.
This protocol was amenable to a wide variety of alkyl ketones and
heteroaryls, thus providing a straightforward method for the late-stage
functionalization of alkylketones and heteroaryls.
An iron-catalyzed redox-neutral, decarboxylative olefination of cycloketone oxime esters with α,β-unsaturated carboxylic acids has been developed. This reaction involves an iminyl radical mediated C-C bond cleavage/radical addition/decarboxylation cascade. This protocol is highlighted by its low-cost catalytic system and readily accessible starting materials, as well as broad substrate scope, thus providing facile access to structurally diverse cyano-containing alkenes.
An efficient iminyl radical-triggered
1,5-hydrogen-atom transfer/Heck-type
coupling cascade has been achieved through visible-light photoredox
catalysis. A variety of unactivated C(sp3)–H bonds
have been alkenylated efficiently and selectively with easily available
alkenes, providing an elegant route to γ-alkenylated ketone.
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