Transition metal-catalyzed conversion of aldehydes to ketones

Light-Driven Photocatalyst-Free Synthesis of β, δ-Functionalized Ketones from Aldehydes

The synthesis of ketones has been a long focus of chemistry research, on account of its unique reactivity. Herein, we report a simple light-driven photocatalyst-free synthesis of β, δ-functionalized ketones from aldehydes, using inexpensive and commercially abundant feedstock chemicals. This reaction is enabled by the direct acyl radical generation via hydrogen atom transfer and the subsequent radical addition process, avoiding the need for prefunctionalized substrates and organometallic reagent.

One-Pot Transformation of Aldehydes to Ketones via Minisci-Type Reaction of Imines

A method for the conversion of aldehydes to ketones via the preliminary formation of aldiminines is described. The imines are involved in acid promoted Minisci-type reaction with alkyl radicals generated from esters of N-hydroxylphthalimide under photoredox conditions. Aminyl radical cations formed after the addition of the iminium ions are believed to be key intermediates, which determine the reaction outcome.

Ketones from aldehydes via alkyl C(sp3)-H functionalization under photoredox cooperative NHC/palladium catalysis

Direct synthesis of ketones from aldehydes features high atom- and step-economy. Yet, the coupling of aldehydes with unactivated alkyl C(sp³)-H remains challenging. Herein, we develop the synthesis of ketones from aldehydes via alkyl C(sp³)-H functionalization under photoredox cooperative NHC/Pd catalysis. The two-component reaction of iodomethylsilyl alkyl ether with aldehydes gave a variety of β-, γ- and δ-silyloxylketones via 1,n-HAT (n = 5, 6, 7) of silylmethyl radicals to generate secondary or tertiary alkyl radicals and following coupling with ketyl radicals from aldehydes under photoredox NHC catalysis. The three-component reaction with the addition of styrenes gave the corresponding ε-hydroxylketones via the generation of benzylic radicals by the addition of alkyl radicals to styrenes and following coupling with ketyl radicals. This work demonstrates the generation of ketyl radical and alkyl radical under the photoredox cooperative NHC/Pd catalysis, and provides two and three component reactions for the synthesis of ketones from aldehydes with alkyl C(sp³)-H functionalization. The synthetic potential of this protocol was also further illustrated by the late-stage functionalization of natural products.

Iron-catalysed quinoline synthesis via acceptorless dehydrogenative coupling

An iron-catalysed atom-economical and straightforward methodology for the synthesis of quinolines from α-2-aminoaryl alcohols and secondary alcohols is presented.