RESUMO
Alkyne 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 ß-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 ß-regioselectively. Moreover, the method can be extended to the ß- 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.
RESUMO
Herein, we report the metal-free hydration of pyridine-SF4-alkynes, under acidic conditions and with reaction durations ranging from 5 min to 10 h at room temperature, to synthesize pyridine-SF4-methyl ketones in yields of 59-93%. Further, we demonstrate the synthetic applications of the synthesized pyridine-SF4-methyl ketones, such as chlorination, NaBH4 reduction, Baeyer-Villiger oxidation, and the generation of enol-triflates. These compounds hold promise as useful building blocks in the syntheses of a wide range of SF4-containing drug candidates.
