反应详情

9.8 g 7-hydroxy-2-methyl-4H-1-benzopyrane-4-on in 20 cm3 dry pyridine and 20 cm3 acetic anhydride was left to stand for 24 hours. The obtained solution was admixed with the mixture of ice, water and hydrochloric acid and the precipitate [11 g of 7-acetoxy-2-methyl-4H-1-benzopyrane-4-on, m.p. 94°-95° C. from benzene] was filtered. The acetoxy compound was hydrogenated in glacial acetic acid at 60° C. in the presence of a palladium on charcoal catalyst till it absorbed 3 molar equivalents of hydrogen, then after filtration and evaporation 11.5 g 7-acetoxy-2-methyl-3,4-dihydro-2H-1-benzopyrane-4-on (m.p. 66°-68° C. from ethanol) was obtained. This compound was hydrolyzed hot in the mixture of 100 cm3 methanol and 1.5 cm3 concentrated hydrochloric acid. The solvent was distilled off, the residue was subjected to fractionated distillation to obtain 6.5 g 7-hydroxy-2-methyl-3,4-dihydro-2H-1-benzopyrane (b.p. 85°-90° C./26 Pa); starting from this compound and following the process of example 5 (b), using a piperidine catalyst and 1-chloro-2,3-epoxypropane reagent, 1-chloro-3-(2-methyl-3,4-dihydro-2H-1-benzopyrane-7-yloxy)-2-propanol (m.p. 70°-72° C.) was obtained.

1. filtrationthe precipitate [11 g of 7-acetoxy-2-methyl-4H-1-benzopyrane-4-on, m.p. 94°-95° C. from benzene] was filtered
2. customwas hydrogenated in glacial acetic acid at 60° C. in the presence of a palladium on charcoal catalyst till it
3. customabsorbed 3 molar equivalents of hydrogen
4. filtrationafter filtration
5. customevaporation 11.5 g 7-acetoxy-2-methyl-3,4-dihydro-2H-1-benzopyrane-4-on (m.p. 66°-68° C. from ethanol)
6. customwas obtained
7. distillationThe solvent was distilled off
8. distillationthe residue was subjected to fractionated distillation