3.1.3. Synthesis of Compounds **8a–d**

(+)-Myrtenal was synthesized according to the procedure [46] by the oxidation of (+)-α-pinene using t-BuOOH/SeO<sup>2</sup> system with a 57% yield. (−)- The (+)-myrtenols were synthesized from the corresponding aldehydes via reduction to alcohols with NaBH4, as described above. NaBH<sup>4</sup> (10.3 mmol) was added to a cooled (0–5 ◦C) solution of 10.3 mmol of the appropriate aldehyde in methanol (20 mL), and the reaction mixture was stirred for 3 h at room temperature. Then, 5% aqueous HCl was added to reach a pH of 4–5. The solvent was distilled off and the product was extracted using ether and dried with Na2SO4. The solvent was evaporated; the resulting alcohols (58% and 54% yields) were used in the synthesis without purification.

Bromides **8a–d** were synthesized from geraniol, (−)-nopol, and (−)- and (+)-myrtenols via the aforementioned reaction with PBr3. PBr<sup>3</sup> (8.9 mmol) was added to a cooled (0–5 ◦C) solution of the corresponding monoterpenoid alcohols (26.7 mmol) in dry ether (30 mL), and the reaction mixture was stirred for 2 h at room temperature. Saturated aqueous NaHCO<sup>3</sup> was added, and the product was extracted with ether. The extracts were washed with brine, dried with Na2SO4, and evaporated. Compounds **8a**, **8c**, and **8d** (with yields of 91%, 55%, and 60%, respectively) were sufficiently pure and used for the next step without purification. The compound **8b** was purified by column chromatography on SiO2, eluent–hexane (yield 24%).
