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Gold-Catalyzed Oxidations of 1,3-Diynamides with C(1) versus C(3) Regioselectivity: Catalyst-Dependent Oxidative Cyclizations in the C(3) Oxidation

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journal contribution
posted on 21.05.2020, 16:40 by Manisha Skaria, Yu-Chen Hsu, Yan-Ting Jiang, Ming-Yi Lu, Tung-Chun Kuo, Mu-Jeng Cheng, Rai-Shung Liu
This work reports two distinct paths in catalytic oxidations of 1,3-diynamides with 8-methylquinoline oxide. A typical C(1) regioselectivity was observed for aryl-substituted 1,3-diyn-1-amides, whereas an unexpected C(3) regioselectivty occurred for 5-hydroxy1,3-diyn-1-amides. We focused on the C(3) oxidations of 5-hydroxy1,3-diyn-1-amides because we observed two oxidative cyclizations of the same substrates to yield 2-aminomethylenefuran-3­(2H)-ones and 2-amino-4H-pyran-4-ones using AuCl3 and a cationic gold catalyst, respectively. Density functional theory calculations were performed to rationalize the C(3) regioselectivity on 5-hydroxy1,3-diyn-1-amides.