Discovery of a New Class of Inhibitors of Vaccinia Virus Based on (−)-Borneol from Abies sibirica and (+)-Camphor

: A series of the bornyl ester/amide derivatives with N-containing heterocycles were designed and synthesized as vaccinia virus (VV) inhibitors. Bioassay results showed that among the designed compounds, derivatives 6, 13, 14, 34, 36 and 37 showed the best inhibitory activity against VV with the IC50 values of 12.9, 17.9, 3.4, 2.5, 12.5 and 7.5 μm, respectively, and good cytotoxicity. The primary structure-activity relationship (SAR) study suggested that the combination of a saturated N-heterocycle, such as morpholine or 4-methylpiperidine, and a 1,7,7-trimethylbicyclo[2.2.1]heptane scaffold was favorable for antiviral activity.