The δ C-H amination of unactivated, secondary C-H bonds to form a broad range of functionalized pyrrolidines has been developed via a triiodide (I3−)-mediated strategy. By in situ (i) oxidation of sodium iodide and (ii) sequestration of the transiently generated iodine (I2) as I3−, this approach precludes undesired I2− mediated decomposition that can otherwise limit synthetic utility to only weak C-H bonds. The mechanism of this triiodide-mediated cyclization of unbiased, secondary C-H bonds, via thermal or photolytic initiation, is supported by NMR and UV-Vis spectroscopic data and intercepted intermediates.

Single-electron reduction of a carbonyl to a ketyl enables access to a polarity-reversed platform of reactivity for this cornerstone functional group. However, the synthetic utility of the ketyl radical is hindered by the strong reductants necessary for its generation, which also limit its reactivity to net reductive mechanisms. Herein, we report a strategy for net redox-neutral generation and reaction of ketyl radicals. The in situ conversion of aldehydes to α-acetoxy iodides lowers their reduction potential (Δ 1200 mV), allowing for milder access to the corresponding ketyl radicals and an oxidative termination event. Upon subjecting these iodides to a Mn2(CO)10 pre-catalyst and visible light irradiation, an atom transfer radical addition (ATRA) mechanism affords a broad scope of vinyl iodide products with high Z-selectivity.

Dimethoxybenzitripyrranes were prepared in excellent yields by reacting benzene dicarbinols with BF3·Et2O and excess pyrrole in refluxing 1,2-dichloroethane. Reaction with a pyrrole dialdehyde in the presence of TFA, followed by oxidation with DDQ, afforded good yields of meso-diphenyldimethoxybenziporphyrins. These dimethoxyporphyrinoids exhibited weakly diatropic properties that were enhanced upon protonation. The dimethoxybenzitripyrranes also reacted with a thiophene dicarbinol to give dimethoxythiabenziporphyrins, and the nonplanar nature of this system was demonstrated by X-ray crystallography. The dimethoxybenziporphyrins reacted with palladium(II) acetate to give the related organometallic derivatives, but the thiabenziporphyrins underwent a demethylation to afford palladium(II) thiaoxybenziporphyrins. Related palladium(II) complexes were also prepared from previously reported thiacarbaporphyrinoids. The X-ray structure for one of the complexes showed that the six-membered ring is very distorted and the thiophene ring is strongly tilted out of the plane of the macrocycle. The dimethoxybenzitripyrranes also reacted with dimethoxybenzene dicarbinols to give the first examples of dibenziporphyrins, thereby further demonstrating the versatility of this synthetic methodology.

Fosu, Hambira, and colleagues describe the direct C-H functionalization of medicinally relevant arenes or heteroarenes. This strategy is enabled by transient generation of reactive, non-symmetric iodanes from anions and PhI(OAc) 2 . The site-selective incorporation of Cl, Br, OMs, OTs, and OTf to complex molecules, including within medicines and natural products, can be conducted by the operationally simple procedure included herein. A computational model for predicting site selectivity is also included.

The first catalytic strategy to harness imidate radicals has been developed. This approach enables alkene difunctionalization of allyl alcohols by photocatalytic reduction of their oxime imidates. The ensuing imidate radicals undergo consecutive intra- and intermolecular reactions to afford (i) hydroamination, (ii) aminoalkylation, or (iii) aminoarylation, via three distinct radical mechanisms. The broad scope and utility of this catalytic method for imidate radical reactivity is presented, along with comparisons to other N-centered radicals and complementary, closed-shell imidate pathways.