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Updated: Jan 25, 2026
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Published on: July 28, 2022
Diketone-Enabled Regioselective Cobalt-Catalyzed C-H/N-H Activation with Alkyl Alkynes
Jia-Wei Li1, Yu-Yan Tan2, Xiao-Hong Chen2
1School of Chemistry and Chemical Engineering, Zhoukou Normal University, Zhoukou 466001, P. R. China.
None:
Annulation of alkynes with C-H/N-H bonds is a green and efficient method for constructing lactams. Controlling the regioselectivity of unsymmetric alkynes, especially alkyl-substituted alkynes, remains challenging. Herein, we report a regioselective annulation of C-H and N-H bonds with alkyl alkynes catalyzed by cobalt using diketone. This transformation has excellent functional group tolerance and a wide substrate scope. Mechanistic experiments demonstrate that the 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD) ligand plays a crucial role in this reaction.
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02:27Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
02:39Nomenclature of Alkynes
02:35Regioselectivity of Electrophilic Additions-Peroxide Effect
02:45Alkyl Halides
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...