Construction of heterocyclic scaffolds via transition metal-catalyzed sp3 C–H functionalization

Transition metal-catalyzed sp3 C-H activation and intramolecular C-N coupling to construct nitrogen heterocyclic scaffolds

Nitrogen heterocycles are of great medicinal importance, and the construction of nitrogen heterocyclic scaffolds has been one of the focuses in synthetic organic chemistry. Recently, the strategy of transition metal-catalyzed sp3 C-H activation and intramolecular C-N coupling to construct nitrogen heterocyclic scaffolds has been well developed. Palladium, copper, silver, nickel, cobalt, ruthenium and rhodium catalysis were successfully used for the construction of nitrogen heterocyclic scaffolds, aziridines, azetidines, pyrrolidines, pyrrolidine-2,5-diones, indolines, isoindolines, isoindolinones, tetrahydropyridines, oxazolidinones, oxazinanones, β-lactams, γ-lactams etc., which have been synthesized by the sp3 C-H activation strategy. Here, we summarize the progress of transition metal-catalyzed sp3 C-H activation/intramolecular C-N bond formation, and introduce both the reaction development and mechanisms in numerous synthetically useful intramolecular sp3 C-H catalytic aminations/amidations.

nBu4NI-Mediated oxidation of methyl ketones to α-ketoamides: using ammonium, primary and secondary amine-salt as an amine moiety

Presented is the first example of synthesizing an array of primary-, secondary-, and tertiary-α-ketoamides in moderate to excellent yields with a catalyst nBu₄NI from methyl ketones and amine/ammonium salts under mild conditions using oxidant TBHP.

Synthesis and Application of Tetrahydro-2H-fluorenes by a Pd(0)-Catalyzed Benzylic C(sp(3) )-H Functionalization

A new method has been developed for the synthesis of tetrahydro-2H-fluorenes based on a Pd(0)-catalyzed benzylic C(sp(3) )-H functionalization. Importantly, the success of the cyclization step was dependent on there being substituents at the two positions ortho to the benzylic group to avoid an undesired C(sp(2) )-H functionalization. This method was subsequently used to prepare the right-hand fragment of the hexacyclic triterpenoid benzohopanes, and therefore represents a powerful tool for the construction of the related compounds.