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Tertiary Carbinamine Synthesis by Rhodium‐Catalyzed [3+2] Annulation of N‐Unsubstituted Aromatic Ketimines and Alkynes
Author(s) -
Sun ZhongMing,
Chen ShuoPing,
Zhao Pinjing
Publication year - 2010
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.200902814
Subject(s) - annulation , chemistry , rhodium , imine , alkyne , indene , catalysis , medicinal chemistry , isoquinoline , hydroamination , toluene , intramolecular force , indane , ligand (biochemistry) , organic chemistry , biochemistry , receptor
A convenient and waste‐free synthesis of indene‐based tertiary carbinamines by rhodium‐catalyzed imine/alkyne [3+2] annulation is described. Under the optimized conditions of 0.5–2.5 mol % [{(cod)Rh(OH)} 2 ] (cod=1,5‐cyclooctadiene) catalyst, 1,3‐bis(diphenylphosphanyl)propane (DPPP) ligand, in toluene at 120 °C, N‐unsubstituted aromatic ketimines and internal alkynes were coupled in a 1:1 ratio to form tertiary 1 H ‐inden‐1‐amines in good yields and with high selectivities over isoquinoline products. A plausible catalytic cycle involves sequential imine‐directed aromatic CH bond activation, alkyne insertion, and a rare example of intramolecular ketimine insertion into a Rh I –alkenyl linkage.