Generation and Radical-Radical Cross-Coupling of Alkenyloxy Radical.

Alkene-attached oxygen radicals are rarely used, as highly reactive oxygen radicals are incompatible with the alkene moiety. The direct radical-radical cross-coupling of O radicals is also challenging (limited to N-O bond formation) because of the lack of suitable persistent radical species. This study demonstrated the feasibility of using Breslow intermediate radical (BIR) as a persistent radical to capture unstable π-conjugated O radicals and allow the C-O radical-radical cross-coupling.

Synthesis of Thioesters from Aldehydes via N-Heterocyclic Carbene (NHC) Catalyzed Radical Relay.

We have developed an efficient N-heterocyclic carbene (NHC)-catalyzed thioesterification of aldehydes using N-thiosuccinimides as the thiolation reagent. This organocatalyzed transition involves the generation of sulfur radicals by single electron transfer of the Breslow enolate (generated from aldehyde and NHC catalyst) with N-thiosuccinimides. This method offers facile access to various highly functionalized thioesters and exhibits good chemical yields and functional group tolerance.

N-Heterocyclic-Carbene-Catalyzed C-H Acylation via Radical Relay.

A method of N-fluorocarboxamide-directed N-heterocyclic-carbene (NHC)-catalyzed benzylic C-H acylation with aldehydes via the hydrogen atom transfer strategy is disclosed. This transformation involves a sequence of single-electron transfer, 1,5-hydrogen atom transfer, and radical cross-coupling steps. This method offers facile access to various highly functionalized ketones and exhibits good chemical yields and functional group tolerance.

Regioselective intramolecular Markovnikov and anti-Markovnikov hydrofunctionalization of alkenes via photoredox catalysis.

Highly regioselective Markovnikov hydrofunctionalization of alkenes was successfully realized via photoredox catalysis by introducing a urea group and fine tuning the hydrogen atom transfer catalysts. The anti-Markovnikov hydroamination of alkenes was also achieved with high yields and stereoselectivities in this work.

Hydrogen bond directed aerobic oxidation of amines via photoredox catalysis.

An application of H-bonding interactions for directing the α-C-H oxidation of amines to amides and amino-ketones catalyzed by an organic photocatalyst is reported. The high efficiency of this method is demonstrated by the aerobic oxidation of pyrrolidines, diarylamines and benzylamines bearing urea groups with high yields and a wide substrate scope.

Visible light-induced cyclization reactions for the synthesis of 1,2,4-triazolines and 1,2,4-triazoles.

A novel method for concisely synthesizing 1,2,4-triazolines via [3+2] cyclization under visible light is reported. These compounds can be easily converted into 1,2,4-triazoles under basic or photoredox conditions. The application of the 1,2,4-triazoles was also investigated via mild operations.