Iron is one of the most attractive catalysts, especially for aromatic C–H functionalizations. However, stoichiometric amounts of oxidants and strong carbanions are required, and C–H tertiary alkylation, especially with electron-deficient alkyl groups, is unexplored. In this paper, we describe the development of iron-catalyzed selective C–H tertiary alkylations with heteroaromatics, in which an iron salt acts as a single-electron source and enhances the reactivity of a tertiary alkyl radical generated from α-bromocarbonyl compounds. Our established methodology was demonstrated in the efficient synthesis of various quaternary carbon atoms under very simple conditions.

Ketones with a 2-nitrophenyl group at the α-position were treated with sodium hydroxide in methanol at 60 °C. Under these conditions, enolates derived from the ketones intramolecularly reacted with the nitro group to form a variety of nitrones. Additional experimental results, including the unexpected isolation of N-hydroxyindolinone as a byproduct, led to a proposed reaction mechanism, occurring via an α-hydroxyketone. The resultant nitrones underwent inter- and intramolecular 1,3-dipolar cycloaddition with olefins to afford polycyclic isoxazolidines.

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The [5-7-6-3] tetracyclic core of premyrsinane diterpenes was convergently synthesized via the stereoselective three-component coupling of a 2-propenyl unit, an enone, and an aldehyde, followed by the relay ring-closing metathesis...