A new synthetic access to N-alkylated nitrones through Lewis acid-catalyzed conjugate additions of aldoximes

In the presence of Lewis acid catalysts, aldoximes react with α,β-unsaturated carbonyl compounds at room temperature to give N-alkylnitrones in good yields. Combination of two Lewis acid catalysts, zinc(II) iodide/boron trifluoride etherate (50 mol%/50 mol%), is the best choice to mediate the reactions producing N-alkylated nitrones in excellent yields. In this procedure, a variety of aldoximes and α,β-unsaturated carbonyl acceptors can be employed.