Synthesis of α,β-Unsaturated Carbonyl Compounds via Cu/TEMPO/O2 Aerobic Catalytic System.

An N,N,N-type Cu(Ⅱ) complex-catalyzed desaturation method for converting alcohols, ketones, lactones, and lactams to their α,β-unsaturated carbonyl compounds is reported. The dehydrogenation reaction can be conducted with a green terminal oxidant O2 without requiring strong acid/base or stoichiometric oxidants. The Cu(Ⅱ) complex/TEMPO/O2 system uses a non-noble catalyst, and a green terminal oxidant as well as demonstrates high activity and functional group tolerance.

Visible-Light-Initiated Air-Oxygenation of Alkylarenes to Carbonyls Mediated by Carbon Tetrabromide in Water.

Synthesizing benzyl skeleton derivatives via direct oxidation of functionalized benzylic C-H bonds has received extensive research attention. Herein, a method was developed to prepare carbonyl compounds via photoinduced aerobic oxidation of ubiquitous benzylic C-H bonds mediated by bromine radicals and tribromomethane radicals. This method employed commercially available CBr as a hydrogen atom transfer reagent precursor, air as an oxidant, water as a reaction solvent, and tetrabutylammonium perchlorate (TBAPC) as an additive under mild conditions.

Visible-Light-Driven Organocatalytic Alkoxylation of Benzylic C-H Bonds.

A variety of strategies for direct alkoxylation of the benzyl C-H bond have been developed toward the construction of benzyl ethers. The light-induced benzyl C-H bond alkoxylation provides an alternative strategy for the synthesis of these important intermediates. The photocatalyzed alkoxylation of the benzyl C-H bond has dominated by metal-catalyzed methods.

Highly Active and Robust Ruthenium Complexes Based on Hemilability of Hybrid Ligands for C-H Oxidation.

Evaluation of the hemilability of hybrid ligands provides a key to understand the metal-ligand cooperation in transition metal catalysis. Here, we design and synthesize a type of Ru complexes based on the hemilability of N-heterocyclic carbenes (NHCs), pyridine, and pyrazole, to compare their activity with other reported Ru catalysts in benzylic C-H oxidation. The Ru catalysts showed ultrastrong catalytic activity in water at room temperature and achieved a turnover frequency (TOF) of 114 h, which is the highest TOF value ever reported for Ru-catalyzed benzylic C-H oxidation.