Regio‐ and Z‐Selective Alkyne Hydroamination and Hydrophenoxylation using Tetrafluoro‐λ6‐Sulfanyl Alkynes under Superbasic, Naked Anion Conditions

Abstract

AbstractAlkyne hydroamination is an effective approach for the production of enamines and enamine‐containing N‐heterocycles. However, stereoselectivity control is a considerable challenge in this reaction because of the electronic repulsion between an incoming nitrogen lone pair and the alkyne π‐system. Herein, we propose a methodology involving β‐regio‐ and Z‐selective alkyne hydroamination by using tetrafluoro‐λ6‐sulfanyl (SF4) alkynes under superbasic, naked anion conditions. The reaction is compatible with a wide variety of N‐heterocycles, including indoles, carbazoles, pyrazoles, and imidazoles, and selectively furnishes SF4‐linked Z‐vinyl enamines with β‐regioselectively. Moreover, the method can be extended to the β‐ and Z‐controlled, base‐mediated alkyne hydrophenoxylation with phenols to provide SF4‐linked Z‐vinyl ethers in high yields. As the SF4 unit has attracted attention as a bioisostere for alkynes, p‐benzenes, bicyclo[1.1.1]pentyl (BCP) groups, and cubanes in medicinal chemistry, this chemistry represents an effective approach to creating novel drug candidates incorporating SF4‐containing molecules.