91819-58-8

1686-14-2

18383-51-2

23727-15-3

The general procedure for the synthesis of trans-pinocampheol and (S)-2-(2,2,3-trimethylcyclopent-3-en-1-yl)acetaldehyde from α-pinocampheol as a raw material was as follows: firstly, α-pinocampheol epoxide 6 was prepared according to the literature method [17] from (-)-α-pinocampheol (7) (Aldrich, [α]D20 -48.4 (pure)). p-toluenesulfonic acid mono hydrate (0.299 g, 1.57 mmol) was added to a solution of N-methyl-2-pyrrolidone (1.35 g, 13.6 mmol) in dichloromethane (15 ml) and stirred for 2 min. Subsequently, a dichloromethane (15 ml) solution of α-pinene epoxide 6 (1.016 g, 6.68 mmol) was slowly added over 10 minutes. The reaction mixture was continued to be stirred at room temperature for 3 h, after which the organic phase was separated by dilution with 25 ml of water with vigorous stirring for 10 min. The aqueous phase was extracted with dichloromethane (20 ml). The organic layers were combined, dried with anhydrous sodium sulfate and concentrated in vacuum. The residue was purified by silica gel column chromatography (17 g SiO2) using a 0 to 50% ether-hexane gradient elution to afford (-)-trans-vanillinol (3) (0.165 g, 1.09 mmol, 16%, [α]D23 -134.9 (c 0.90, CHCl3), respectively; literature value [11] [α]D23 -139 (c1.2)) and lobenic enal 8 (0.406 g, 2.67 mmol, 40%). The spectral data of compounds 3 and 8 are in agreement with literature reports [29,30].