Enantioselective benzylic C-H arylation via photoredox and nickel dual catalysis.

The asymmetric cross-coupling reaction is developed as a straightforward strategy toward 1,1-diaryl alkanes, which are a key skeleton in a series of natural products and bioactive molecules in recent years. Here we report an enantioselective benzylic C(sp3)-H bond arylation via photoredox/nickel dual catalysis. Sterically hindered chiral biimidazoline ligands are designed for this asymmetric cross-coupling reaction. Readily available alkyl benzenes and aryl bromides with various functional groups tolerance can be easily and directly transferred to useful chiral 1,1-diaryl alkanes including pharmaceutical intermediates and bioactive molecules. This reaction proceeds smoothly under mild conditions without the use of external redox reagents.

DMSO-Triggered Complete Oxygen Transfer Leading to Accelerated Aqueous Hydrolysis of Organohalides under Mild Conditions.

Addition of DMSO is found to greatly accelerate the aqueous hydrolysis of organohalides to alcohols, providing a neutral, more efficient, milder and more economic process. Mechanistic studies using 18 O-DMSO and 18 O-H2 O showed that, contrary to the opinion that DMSO works as a dipolar solvent to enhance water's nucleophilicity, the accelerating effect comes from a complete oxygen transfer from DMSO to organohalides through generation of ROS+ Me2 ⋅X- salts through C-O bond formation, followed by O-S bond disassociative hydrolysis of ROS+ Me2 ⋅X- with water. This method is applicable to a wide range of organohalides and thus may have potential for practical industrial application, owing to easy recovery of DMSO from the H2 O/DMSO mixture by regular vacuum rectification.

Visible-Light-Promoted Metal-Free Aerobic Oxidation of Primary Amines to Acids and Lactones.

A unique metal-free aerobic oxidation of primary amines via visible light photocatalytic double carbon-carbon bonds cleavage and multi carbon-hydrogen bonds oxidation was observed. Aerobic oxidation of primary amines could be controlled to afford acids by using dioxane with 18 W CFL, and lactones by using DMF with 8 W green LEDs, respectively. A plausible mechanism was proposed based on control experiments. This observation showed direct evidences for the fragmentation in the aerobic oxidation of aliphatic primary amines.