1) Synthesis of α-ionone oxime compound 2
10.0 g (52 mmol) of α-ionone was dissolved in 20 mL of ethanol and added to the flask. 3.8 g (60 mmol) of hydroxylamine hydrochloride, 6.4 g (70 mmol) of sodium acetate and 15 mL of deionized water were sequentially added to the flask at one time. After the addition, the temperature of the system was raised to 55°C, and the reaction time was controlled for 3h. After the reaction, 60 mL of deionized water was added to the system, extracted three times with 60 mL of ethyl acetate respectively, and the organic phases were combined. The organic phase was washed with 60 mL of saturated aqueous sodium bisulfite solution, dried over anhydrous MgSO4, and the solvent was evaporated to obtain an orange liquid, which was placed in the refrigerator to become a solid, namely α-ionone oxime compound 2, with a yield of 99.6%. The molecular weight of compound 2 determined by gas mass spectrometry was 207, which was consistent with the calculated molecular weight of α-ionone oxime. H NMR spectrum shows that there are 22 hydrogens, including 4 methyl groups, with chemical shifts δH of 2.00, 1.55, 0.89, and 0.81, respectively. The chemical shifts of 3 olefin hydrogens are 6.12, 5.86, and 5.42. The C NMR spectrum shows that it contains 13 carbons, including one oxime group, the chemical shift δC is 155.7, and the chemical shifts δC of the four olefin carbons are 136.5, 132.8, 127.9, and 120.9, respectively. Combining gas mass spectrometry and nuclear magnetic analysis, the product was determined to be α-ionone oxime.
2) Synthesis of α-ionone epoxime compound 3
5.1 g (24 mmol) of α-ionone oxime 2 was added to 70 mL of deionized water, added to the reaction flask, and the temperature of the system was maintained at 0°C. Under stirring, slowly add 3.7mL CTAOH (10wt%), the system changes from colorless and transparent to milky white liquid, and then slowly add a mixture of 35mL hydrogen peroxide (30%) and 5mL lithium hydroxide (6mol/L), after the addition, the system The temperature was raised to 25°C and the reaction time was 15h. After the reaction was completed, 150 mL of deionized water was added, extracted with 100 mL of dichloromethane for three times respectively, the organic phases were combined, dried with anhydrous MgSO4, and the solvent was evaporated to obtain α-ionone epoxidized oxime compound 3 with a yield of 98.8 %.
3) Synthesis of Damascenone
Add 4.0 g (19 mmol) of α-ionone isoxazole derivative 4, 70 mL of cyclohexane and 2.0 g (86 mmol) of Na to the three-necked flask, maintain the system temperature at 40 °C, and add 8 mL of absolute ethanol until there is no metal After the sodium remained, the reaction time was 8h; after the reaction was completed, 6g of ammonium chloride and 30mL of deionized water were added, the solution was extracted with 50mL of dichloromethane three times, the organic phases were combined, and then washed with 50mL of saturated aqueous sodium bicarbonate solution. The water was dried with MgSO4; the liquid after the solvent was evaporated was distilled under reduced pressure to obtain Damascenone with a yield of 90.8%.