Robust continuous-flow synthesis of deuterium-labeled ¢-nitroalcohols catalyzed by basic anion exchange resin

A practical and efficient continuous-flow system was developed for the synthesis of site-selectively deuterium-labeled ¢- nitroalcohols by using the tertiary amine-functionalized basic anion exchange resin, WA30, as a heterogeneous organocatalyst. For this system, WA30 was prepacked in a cartridge under metal-free conditions. The system was operated by pumping a solution of aldehydes or ketones, as electrophiles, and nitroalkanes in a solvent system of deuterium oxide and THF in the catalyst cartridge. Various deuterated ¢-nitroalcohols were obtained in moderate to excellent yields with high deuteration efficiencies. The continuous-flow system was applied in continuous synthesis for at least 72 h without degradation of the heterogeneous organocatalyst activity.