An efficient method for intermolecular branch-selective allylic C-H amidation has been accomplished via Ir(III) catalysis. The reaction proceeds through initial allylic C-H activation, supported by the isolation and crystallographic characterization of an allyl-Ir(III) intermediate, followed by a subsequent oxidative amidation with readily available dioxazolones as nitrenoid precursors. A diverse range of amides are successfully installed at the branched position of terminal alkenes in good yields and regioselectivities. Importantly, the reaction allows the use of amide-derived nitrenoid precursors avoiding problematic Curtius-type rearrangements.

The total synthesis of the tunicate metabolite mandelalide A and the correction of its originally assigned stereochemistry are reported. Key features of the convergent, fully stereocontrolled route include the use of a Prins cyclization for the diastereoselective construction of the tetrahydropyran subunit, Rychnovsky-Bartlett cyclization for the preparation of the tetrahydrofuran moiety, Suzuki coupling, Horner-Wadsworth-Emmons macrocyclization, and glycosylation to append the L-rhamnose-derived pyranoside.

C–H activation reactions enable chemists to unveil new retrosynthetic disconnections and streamline conventional synthetic approaches. A longstanding challenge in C–H activation is the inability to distinguish electronically and sterically similar C–H bonds. Although numerous synergistic combinations of transition-metal complexes and chelating directing groups have been utilized to distinguish C–H bonds, undirected regioselective C–H functionalization strategies remain elusive. Herein, we report a regioselective C–H activation/amination reaction of various unsymmetrical dialkyl-substituted alkenes. The regioselectivity of C–H activation is correlated to the electronic properties of allylic C–H bonds indicated by the corresponding 1 J CH coupling constants. A linear relationship between the difference of 1 J CH coupling constants of the two competing allylic C–H bonds (Δ 1 J CH ) and the C–H activation barriers (ΔΔG ‡ ) has also been determined.

An intramolecular Ir(III)-catalyzed regiodivergent oxyamination of unactivated alkenes provides valuable γ-lactams, γ-lactones and δ-lactams. The regioselectivity is controlled by the electronically tunable cyclopentadienyl Ir(III)-complexes enabling oxyamination via either 5-exo or 6-endo pathways. With respect to the mechanism, we propose a highly reactive [3.1.0] bicycle intermediate derived from Ir(V) nitrene-mediated aziridination to be a key intermediate toward the synthesis of γlactams.

A revised configurational assignment for the marine metabolite lagunamide A is proposed and validated by total synthesis.