反应详情

3.5 g (13.2 mmol) of 4,5-difluoro-2-methyl-7-propyl-7H-furo[3,2-f]chromene are hydrogenated for a few minutes in toluene using elemental hydrogen in the presence of Pd/C (5% Pd). The reaction soln. is concentrated to dryness, and the residue is purified by column chromatography (SiO2, n-heptane:1-chlorobutane=2:1). The further purification is carried out by recrystallisation from ethanol and subsequent absorptive (SiO2, n-heptane:1-chlorobutane=3:1) filtration, giving 4,5-difluoro-2-methyl-7-propyl-8,9-dihydro-7H-furo[3,2-f]chromene as a colourless solid having an m.p. of 75° C. (Δ∈c=−7.8).

1. concentrationis concentrated to dryness
2. customthe residue is purified by column chromatography (SiO2, n-heptane:1-chlorobutane=2:1)
3. customThe further purification
4. customis carried out by recrystallisation from ethanol and subsequent absorptive (SiO2, n-heptane:1-chlorobutane=3:1) filtration