cis-resveratrol was prepared as follows:
(1) Synthesis of the compound of formula (V)
Take 0.47g (0.02mol) of sodium metal and add it to 10mL (0.17mol) of absolute ethanol. After the sodium metal is completely dissolved, mix 1.66g (0.01mol) of 3,5-dimethoxybenzaldehyde with 1.47g ( 0.01mol) of p-methoxyphenylacetonitrile was dissolved in 10mL (0.17mol) of ethanol and added to the reaction flask, refluxed at 75°C for 12 hours, cooled, a large amount of light yellow crystals were precipitated, and recrystallized with ethanol to obtain 2.1g of the compound of formula (V), The yield was 71%.
(2) Synthesis of the compound of formula (VI)
Weigh 2.95g (0.01mol) of the compound of formula (V) and dissolve it in 75mL (1.34mol) of ethylene glycol, add 75mL of 15% (0.3mol) sodium hydroxide solution, stir, react at 120°C for 72 hours, cool , acidified to acidity by adding dilute hydrochloric acid, extracted with ethyl acetate, dried and concentrated, and recrystallized from ethanol/water to obtain 2.12 g of light yellow needle crystals, namely the compound of formula (VI), with a yield of 67%.
(3) Synthesis of the mixture of formula (VII) compound and formula (VIII) compound
Weigh 3.14g (0.01mol) of the compound of formula (VI), 3.00g (0.047mol) of copper powder and 30g (0.23mol) of quinoline, stir, react at 220°C for 2 hours, cool to room temperature, and add an appropriate amount of ethyl acetate , washed with dilute hydrochloric acid to acidity, mass fraction 5% sodium hydroxide solution was washed to alkaline, the organic layer was dried, concentrated to obtain light yellow oily liquid 1.92g, i.e. the mixture of formula (VII) compound and formula (VIII) compound, yield 71%.
(4) separation of the mixture of formula (VII) compound and formula (VIII) compound
Add 3.0 g of the obtained mixture of the compound of formula (VII) and compound of formula (VIII) into 1 mL of ethyl acetate to dissolve, load the sample on a column filled with 100 g of silica gel, and wash with a mixed solvent of petroleum ether-chloroform at a volume ratio of 1:8. Elution was carried out by removing solvent, and compound a(VII) 1.2g (yield 60%) and compound b(VIII) 0.6g (yield 20%) were successively obtained.
(5) The compound of formula (II) is the synthesis of trans-resveratrol
Weigh 2.70g (0.01mol) compound of formula (VIII) into a 100mL three-neck round bottom flask, add 40mLCH2Cl2, stir for a while under ice-water bath, slowly add 8mL (0.08mol) BBr3 solution dropwise, after the dropwise addition Stir at room temperature for 13 hours, add a large amount of water, extract with ethyl acetate, dry, concentrate, and recrystallize to obtain 1.90 g of light yellow solid with a yield of 81.5%. The obtained product was analyzed and confirmed to be the compound of formula (II), ie trans-resveratrol.
(6) The compound of formula (I) is the synthesis of cis-resveratrol
Weigh 2.70g (0.01mol) of the compound of formula (VII) into a 100mL three-necked round-bottomed flask, add 40mL (0.63mol) CH2Cl2, stir for a while under ice-water bath, slowly add dropwise 8mL (0.08mol) BBr3 solution , after the dropwise addition, stirred at room temperature for 12 hours, added a large amount of water, extracted with ethyl acetate, dried, concentrated, and recrystallized to obtain 1.75 g of white crystals, with a yield of 76.8%. The obtained product was analyzed and confirmed to be the compound of formula (I), namely cis-resveratrol.
