Tertiary Carbinamine Synthesis by Rhodium‐Catalyzed [3+2] Annulation of N‐Unsubstituted Aromatic Ketimines and Alkynes |
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| Authors: | Zhong‐Ming Sun Dr Shuo‐Ping Chen Pinjing Zhao Prof?Dr |
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| Institution: | Department of Chemistry and Molecular Biology, North Dakota State University, 1231 Albrecht Avenue, P.O. Box 6050, Fargo, ND 58108‐6050 (USA), Fax: (+1)?701‐231‐8831 |
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| Abstract: | 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 1H‐inden‐1‐amines in good yields and with high selectivities over isoquinoline products. A plausible catalytic cycle involves sequential imine‐directed aromatic C? H bond activation, alkyne insertion, and a rare example of intramolecular ketimine insertion into a RhI–alkenyl linkage. |
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| Keywords: | alkynes carbinamines C?H activation ketimines rhodium |
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