Hydroxylamines as Oxygen Atom Nucleophiles in Transition-Metal-Catalyzed Allylic Substitution

摘要

The viability of hydroxylamines as nucleophiles in transition-metal-catalyzed allylic substitutions was examined.We have found that the oxygen atom of hydroxylamines having an N-electron-withdrawing substituent (also known as hydroxamic acids) acts as a reactive nucleophile.The palladium-catalyzed O-allylic substitution of hydroxylamines with allylic carbonate afforded the linear hydroxylamines.The selective formation of the branched hydroxylamines was observed in iridium-catalyzed reaction.Regio- and enantioselective allylic substitution of the unsymmetrical phosphates with hydroxylamines was studied by using the indium complex of chiral pybox ligand.The aqueous-medium reaction with hydroxylamincs proceeded smoothly in the presence of Ba-(OH)_2 centre dot H_2O to give the branched products with good enantioselectivities.