Enantioselective metal-free reduction of ketones by a user-friendly silane with a reusable chiral additive

Iridium-catalyzed reduction of o-hydroxyl phenyl enaminones for the synthesis of propiophenones and their application in 3-methyl chromone synthesis

A method of reducing o-hydroxyphenyl enaminones with silane as the reductant to provide o-hydroxyl propiophenones has been achieved with iridium catalysis. The reduction reactions were found to proceed via the assistance of the hydroxyl group in the phenyl ring. In addition, the o-hydroxyl propiophenone products were used for the easy synthesis of 3-methyl chromones by directly incorporating N,N-dimethyl formamide dimethyl acetal (DMF-DMA) without using any catalyst.

A General Method for Photocatalytic Decarboxylative Hydroxylation of Carboxylic Acids

A general and practical method for decarboxylative hydroxylation of carboxylic acids was developed through visible light-induced photocatalysis using molecular oxygen as the green oxidant. The addition of NaBH₄ to in situ reduce the unstable peroxyl radical intermediate much broadened the substrate scope. Different sp³ carbon-bearing carboxylic acids were successfully employed as substrates, including phenylacetic acid-type substrates, as well as aliphatic carboxylic acids. This transformation worked smoothly on primary, secondary, and tertiary carboxylic acids.

Chiral Brønsted Acid-Catalyzed Metal-Free Asymmetric Direct Reductive Amination Using 1-Hydrosilatrane

The asymmetric direct reductive amination of prochiral ketones with aryl amines using 1-hydrosilatrane with a chiral Brønsted acid catalyst is reported. This is the first known example of chiral Brønsted acid-catalyzed asymmetric reductive amination using a silane as the hydride source. The reaction features a highly practical reducing reagent and proceeds efficiently at room temperature without a specialized reaction setup or equipment to exclude air or moisture. This method provides high conversion and enantiomeric excess up to 84% of the desired chiral secondary amines with minimal side products.