A practical and step-economical nitroso aldol reaction has been developed based on metal-free direct cross-coupling of ready-stock anilines with silyl enol ethers at room temperature affording α-amino ketones in high yields (up to 82%). The protocol features a one-pot cascade of nitroso compound generation, selective C-N bond formation, and N-O bond cleavage using solely inexpensive and user-friendly Oxone and displays remarkable functional group tolerance. The method was further extended to prepare densely functionalized indoles that are otherwise difficult to synthesize.
An unprecedented Henry reaction of in situ generated nitrosocarbonyl intermediates and concomitant denitration cascade has been developed. The reaction is catalyzed by organic base at room temperature offering α-ketoamides, a demanding scaffold for drug discovery, in high yields. An alteration of substitution pattern also produced α-keto oximes, a high-value synthon. The protocol features operational simplicity and broad substrate scope.
A straightforward synthesis of 2-styrylbenzoic acids from aryl carboxylic acids is disclosed through a carboxylate-assisted coupling under Ru(II) catalysis. This protocol is simple and exhibits broad scope with high tolerance of common organic functional groups, providing good to excellent yields of diverse olefinated products. The efficacy of this protocol has been showcased through sequential syntheses of isochromanone, isocoumarin, and formal synthesis of anacardic acid derivative in good yields.
A base promoted vinylogous annulation cascade of alkylidene malononitriles with cyclopentene‐1,3‐diones with a subsequent reduction sequence has been devised to furnish densely functionalized 3‐hydroxyindanone scaffolds in high yields with excellent diastereoselectivity. Unlike preceding approaches that account for the formation of the pentanoid ring, this strategy features construction of the aromatic ring. The protocol is scalable, displays very broad substrates scope including late‐stage functionalization of bioactive estrone, applicable to activated coumarin system, and is suitable to access an indenoquinoline derivative.magnified image
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.orglett.3c00358.Complete experimental details, characterization data for the prepared compounds (PDF)Accession CodesCCDC 2179740 and 2215095 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk
The
divergent reactivity of nitrosocarbonyls in oxidative dearomatization
of β-naphthols is reported. In the presence of quinidine catalyst,
their reactions with α-unsubstituted β-naphthols proceeded
through the N-center to furnish α-imino-β-naphthalenones
in high yields. Upon exposure to α-substituted β-naphthols
in the presence of copper catalyst, an alteration of regioselectivity
was observed to produce α-aminoxylation products. The reaction
is scalable, tolerates a wide spectrum of functional groups, and represents
a rare example of dearomatization of α-unsubstituted β-naphthols.
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