Triflic Acid-Catalyzed Cycloisomerization of 1,6-Enynes: Facile Access to Carbo- and Azaheterocycles

A new and efficient strategy for
enynes cyclization catalyzed by
triflic acid has been described. Various valuable carbocycle-fused
and heterocycle-fused ketones were easily accessed by the formation
of new C–C and C–O bond under benign reaction conditions.
This protocol also provides another opportunity to construct polycyclic
single-nitrogen ketones via a cation-induced cascade cyclization of
polyenynes. Furthermore, antiviral bioassays revealed that a few compounds
exhibited good antiviral activity against tobacco mosaic virus at
a concentration of 200 μg mL–1.