Gold-Catalyzed Iminations of Terminal Propargyl Alcohols with Anthranils with Atypical Chemoselectivity for C(1)-Additions and 1,2-Carbon Migration |
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Authors: | Dr. Manisha Skaria Sayaji Arjun More Tung-Chun Kuo Prof. Dr. Mu-Jeng Cheng Prof. Dr. Rai-Shung Liu |
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Affiliation: | 1. Frontier Research Centers of Fundamental and Applied Science of Matter, Department of Chemistry, National Tsing-Hua University, Hsinchu, 30013 Taiwan;2. Department of Chemistry, National Cheng Kung University, Tainan, 701 Taiwan |
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Abstract: | This work reports gold-catalyzed iminations of terminal propargyl alcohols with anthranils or isoxazoles to yield E-configured α-amino-2-en-1-ones and -1-als with complete chemoselectivity. These catalytic iminations occur exclusively with C(1)-nucleophilic additions on terminal alkynes, in contrast to a typical C(2)-route. For 3,3-dialkylprop-1-yn-3-ols, a methyl substituent is superior to long alkyl chains as the 1,2-migration groups toward α-imino gold carbenes. For secondary prop-1-yn-3-ols, phenyl, vinyl, and cyclopropyl substituents are better than hydrogen as the migrating groups, obviating typical gold carbene reactions. DFT calculations have been performed to rationalize the observed C(1)-regioselectivity and the preferable cyclopropyl migration based on gold carbene pathways. |
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Keywords: | 1,2-migration alkynols anthranils C1-regioselectivity gold catalysis imination |
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