反应详情

温度

65 °C

A mixture of 2-chloro-1,4-naphthoquinone (1.16 g), 4-methoxycyclohexane-1-carboxylic acid (1.3 g) and silver nitrate (0.3 g) were stirred at 65° C. in a mixture of acetonitrile (2.5 ml), sulpholane (7.5 ml) and water (17.5 ml) while a solution of ammonium persulphate (2.3 g) in water (5 ml) was added dropwise during 15 minutes. The reaction mixture was stirred for a further 15 minutes at 65° C., cooled in ice and extracted with ether. The ether extracts were washed with sodium bicarbonate solution, dried and evaporated. The crude product was recrystallised from acetonitrile to yield 2-chloro-3-(4-methoxycyclohexyl)-1,4-naphthoquinone, m.p. 110°-113° C.; the product so obtained (0.9 g) was dissolved in boiling methanol (25 ml) and a solution of potassium hydroxide (0.9 g) in water (9 ml) added dropwise during 10 minutes. The reaction mixture was then refluxed for a further 30 minutes, concentrated hydrochloric acid (5 ml) added dropwise and the mixture cooled in ice. Addition of an equal volume of water precipitated an oil which slowly turned to a semi-solid. Recrystallisation from acetonitrile yielded 2-hydroxy-3-(4-methoxycyclohexyl)-1,4-naphthoquinone, m.p. 152°-155°, shown by n.m.r. to be the pure trans isomer.

1. additionwas added dropwise during 15 minutes
2. temperaturecooled in ice
3. extractionextracted with ether
4. washThe ether extracts were washed with sodium bicarbonate solution
5. customdried
6. customevaporated
7. customThe crude product was recrystallised from acetonitrile