反应详情

温度

200 °C

33.5 g of methyl (RS)-3-(1-cyclopropyl-prop-2-ynyloxy)-4,5-dimethoxy-benzoate were dissolved in 330 ml of N,N-diethylaniline, heated to 200° C. under argon and stirred at 200° C. for a further 5 hrs. The solvent was distilled off at 90° C./1 mbar and the residue was extracted: 2×1.5 l of diethyl ether, 2×1.5 l of 1N HCl, 2×1.5 l of saturated NaCl. The oil obtained was purified by silica gel chromatography with toluene, then toluene/ethyl acetate 9:1. Crystallization was effected from diethyl ether and hexane. Methyl (RS)-2-cyclopropyl-7,8-dimethoxy-2H-1 -benzopyran-5-carboxylate was obtained as white crystals.

1. distillationThe solvent was distilled off at 90° C./1 mbar
2. extractionthe residue was extracted
3. customThe oil obtained
4. customwas purified by silica gel chromatography with toluene
5. customCrystallization