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[摘要]:Hf(OTf)4-catalyzed 1,4-addn. reactions of indole to enones in the presence of pyridinediamine are described. Although a dimer and a trimer of indole were produced under the Hf(OTf)4 catalyzed reaction conditions of indole, the addn. of pyridinediamines (La-f) inhibited such oligomerization reactions. A 1:1 mixt. of Hf(OTf)4 and a pyridinediamine ligand formed a Hf(OTf)4-pyridinediamine complex, which catalyzed the 1,4-addn. reaction very efficiently without the formation of dimer and trimer of indole. The stereochem. of the pyridinediamine ligands was found to play an important role in the relative rate of the reactions. |
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