Hydrochloric Acid → 5,7-Dihydroxyspiro[chroman-2,1'-cyclobutan]-4-one

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

8 g (49.34 mmol) of 1,3,5-trihydroxybenzene dihydrate and 6.64 g (59.21 mmol) of cyclo-butylideneacetic acid (Example 40A) are initially charged, 25 ml (197.4 mmol) of boron trifluoride/diethyl ether complex are added and the mixture is then heated to 70° C. After three hours, the mixture is cooled, poured into 600 ml of ice-water, acidified with 6 N hydrochloric acid and extracted repeatedly with ethyl acetate. The combined organic phases are washed twice with saturated sodium chloride solution, dried over sodium sulfate, filtered and concentrated. The crude product is taken up in dichloromethane and stirred, and insoluble solid is then filtered off. Silica gel is added to the filtrate, the mixture is concentrated and the residue is purified chromatographically on silica gel (mobile phase: cyclohexane→cyclohexane/ethyl acetate 5:1). This gives 4.7 g (43% of theory) of the title compound.

Herkunft & Nachweise