反应详情

0.21 g of 5-benzyloxy-2-(6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)pyridine N-oxide in 90 ml of methanol was hydrogenated over 10% palladium-on-carbon at room temperature and under atmospheric pressure for 30 minutes. The catalyst was removed by filtration and the filtrate was evaporated. The residue was chromatographed on silica gel using dichloromethane/methanol (19:1) for the elution to give 0.05 g of 2-(6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)-5-hydroxypyridine N-oxide in the form of an off-white solid of melting point 224° C. (from ethyl acetate).

1. customThe catalyst was removed by filtration
2. customthe filtrate was evaporated
3. customThe residue was chromatographed on silica gel
4. washfor the elution