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Palladium(II)‐Catalyzed One‐Pot Syntheses of 9‐(Pyridin‐2‐yl)‐9 H ‐carbazoles through a Tandem CH Activation/CX (X=C or N) Formation Process
Author(s) -
Chu JeanHo,
Lin PiShan,
Lee YaMing,
Shen WeiTing,
Wu MingJung
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201101528
Subject(s) - transmetalation , catalysis , chemistry , palladium , reductive elimination , medicinal chemistry , tandem , ligand (biochemistry) , solvent , benzoquinone , combinatorial chemistry , organic chemistry , biochemistry , materials science , receptor , composite material
A new one‐pot synthesis of 9‐(pyridin‐2‐yl)‐9 H ‐carbazoles through the simultaneous CH activation and palladium(II)‐catalyzed cross‐coupling of N ‐phenylpyridin‐2‐amines with potassium aryltrifluoroborates is presented. Silver acetate and 1,4‐dioxane proved to be the best oxidant and solvent, respectively. The product yields fluctuated from modest to excellent and the reaction showed sufficient functional group tolerance. p ‐Benzoquinone served as an important ligand for the transmetalation and reductive elimination steps in the catalytic process. The kinetic isotope effects ( k H / k D ) for the first and second CH activation/CC or CN formation steps were measured as 2.14 and 1.18, respectively. Finally, a rational catalytic mechanism is presented based on all experimental evidence.