Ruthenium-Catalyzed Rearrangementof Aldoximes toPrimary Amides in Water.

The rearrangement of aldoximes to primary amides hasbeen studiedusing the readily available arene-ruthenium(II) complex [RuCl2(η6-C6Me6){P(NMe2)3}] (5 mol %) as catalyst. Reactions proceededcleanly in pure water at 100 °C without the assistance of anycocatalyst, affording the desired amides in high yields (70–90%)after short reaction times (1–7 h). The process was operativewith both aromatic, heteroaromatic, α,β-unsaturated, andaliphatic aldoximes and tolerated several functional groups. Reactionprofiles and experiments using 18O-labeled water indicatethat two different mechanisms are implicated in these transformations.In both of them, nitrile intermediates are initially formed by dehydrationof the aldoximes. These intermediates are then hydrated to the correspondingamides by the action of a second molecule of aldoxime or water. Akinetic analysis of the rearrangement of benzaldoxime to benzamideis also discussed. [ABSTRACT FROM AUTHOR]