We report an approach for the intramolecular C(sp 2 )ÀH amidation of N-acyloxyamides under photoredox conditions to produce d-benzolactams with an aryl-alkyl sbond relocation. Computational studies on the designed reductive single electron transfer strategy led us to identify N-[3,5-bis(trifluoromethyl)benzoyl] group as the most effective amidyl radical precursor. Upon the formation of an azaspirocyclic radical intermediate by the selective ipso-addition with outcompeting an ortho-attack, radical-polar crossover was then rationalized to lead to the rearomative ring-expansion with preferential C À C bond migration.Scheme 1. Radical-polar crossover to access rearomative cyclization products via a radical ipso-addition.

We report herein a series of tailored CpXRh­(LX)Cl catalyst systems for the outer-sphere C–H amidations discovered by high-throughput experimentation. Using a diverse repertoire of Cp-tunable group 9 [CpXMCl2]2 precatalysts in combination with bidentate LX-type co-ligands, we have established a premixing protocol for the fast and convenient in situ generation of an array of half-sandwich metal complexes. Benefitting from the designed multidimensional approach to simultaneously screen the metal center, CpX, LX-type co-ligands, and nitrene precursors, optimal CpXRh­(III)­(LX) catalysts were quickly identified for intra- and intermolecular C–H amidations and also for an enantioselective transformation using N-tosyloxycarbamates as the nitrenoid precursor.

Cyclic volatile methyl siloxanes (cVMS) are anthropogenic chemicals emitted by consumer and industrial products. Evidence from laboratory and ambient studies indicates that cVMS contributes to the formation of secondary organosiloxane...