Development and Mechanistic Insights into Nef Reaction for Preparation of Aldehydes Using Singlet Oxygen

The Nef reaction for conversion of nitro compounds to aldehydes is described. Various functional groups, such as ethers, silyl ethers, acetals or esters, were tolerated to give aldehydes in high yields using Cs₂CO₃ and singlet oxygen as an oxidant. Transformations of nitromethyl groups into hydroxymethyl groups were achieved in a one-pot operation. The mechanism involved in the Nef reaction was studied using ion chromatography and radical scavengers, which resulted in the proposal of two unique reaction pathways.