Hydroxylamines as oxygen atom nucleophiles in transition-metal-catalyzed allylic substitution |
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Authors: | Miyabe Hideto Yoshida Kazumasa Yamauchi Masashige Takemoto Yoshiji |
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Institution: | Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. |
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Abstract: | reaction: see text] 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 iridium complex of chiral pybox ligand. The aqueous-medium reaction with hydroxylamines proceeded smoothly in the presence of Ba(OH)(2).H(2)O to give the branched products with good enantioselectivities. |
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