Propiolamidines I. Syntheses ofN,N′-Disubstituted Phenylpropiolamidines and New Routes to 5-N-Substituted Amino-3-phenylisoxazoles and 5-N-Substituted Amino-1,3-diphenylpyrazoles
Rare-Earth-Metal-Catalyzed Addition of Terminal Monoalkynes and Dialkynes with Aryl-Substituted Symmetrical or Unsymmetrical Carbodiimides
摘要:
A high-efficiency and atom-economic route for the synthesis of N-aryl-substituted propiolamidines was established through the addition of terminal alkynes with aryl-substituted symmetrical or unsymmetrical carbodiimides catalyzed by mixed Tp(Me2)/Cp rare-earth-metal alkyl complexes (TpMe(2))CpLnCH(2)Ph(THF) (1(Ln)). Moreover, the gadolinium alkyl complex 1(Gd) can also serve as a catalyst for the double addition of dialkynes with carbodiimides. Mechanism studies indicated that the variable coordination modes (kappa(3) or kappa(2)) of the Tp(Me2) ligand on the rare-earth-metal species may play an important role in the catalytic cycles.