A solution of β-pinene (25.0 g, 184 mmol) in CH2Cl2 was cooled to -78 ᵒC and ozone bubbled through until a characteristic blue colour was observed (6 hours). The ozone flow was stopped, and nitrogen was bubbled through the solution to remove excess ozone. Triethylamine (51 mL, 0.368 mmol) was added dropwise with stirring while gradually warming to 0 °C. After 1 hour, the reaction was slowly warmed to room temperature and stirred for 18 hr before washing with 1M HCl (5 x 200 mL). The organic layer was dried over MgSO4 and concentrated in vacuo to a pale yellow-green oil which was used without further purification (20.0 g, 145 mmol, 79%).