Photo-induced bromination of (+)-camphene and efficient synthesis of novel camphene-based compounds

The bromination of 1R,4S-2,2-dimethyl-3-methylenebicyclo[2.2.1]heptane and 1S,4R-1-bromomethyl-7,7-dimethylbicyclo[2.2.1]hept-‑2-ene was investigated under various reaction conditions. Additionally, the Suzuki-Miyaura coupling and nucleophilic substitution reactions of 1R,4S-E-3-bromomethylene-2,2-dimethylbicyclo[2.2.1]heptane were studied. The influence of neighboring groups on the rearrangement process was examined, and the mechanisms underlying the formation of di- and tri-brominated rearrangement and non-rearrangement products, along with the role of substituent groups in skeletal rearrangement, were analyzed. The structures of all synthesized compounds were characterized using ¹H NMR, ¹³C NMR, and FTIR, with a few compounds also analyzed by ¹⁹F NMR and X-ray crystallography to confirm their precise structural frameworks. The optical activity of all synthesized chiral compounds was assessed using polarimetry to distinguish between isomers. Furthermore, the coupling constants, as well as shielding and deshielding effects, were evaluated to understand the relationship between substituent groups and the structural skeleton.