反应详情

To a solution of 3-oxo-spiro[5.5]undecane-2-carboxylic acid methyl ester (29.6 g) obtained in Step 3 in a mixed solvent of methanol (200 mL)-tetrahydrofuran (50 mL), sodium borohydride (4.67 g) was added in three portions under ice-cooling, followed by stirring the reaction mixture under ice-cooling for 1 hour. Then, after addition of 1N aqueous hydrochloric acid solution to the reaction mixture, the resulting insolubles were filtered off. Methanol in the filtrate was evaporated off in vacuo, followed by extraction with ethyl acetate. The organic layer was washed with saturated brine, dried and concentrated. The residue was purified by column chromatography on silica gel (ethyl acetate:hexane (volume ratio)=1:10 to 1:3) to give trans-3-hydroxy-spiro[5.5]undecane-2-carboxylic acid methyl ester (4.15 g) and cis-3-hydroxy-spiro[5.5]undecane-2-carboxylic acid methyl ester (4.9 g).

1. temperaturecooling
2. temperaturecooling for 1 hour
3. filtrationthe resulting insolubles were filtered off
4. customMethanol in the filtrate was evaporated off in vacuo
5. extractionfollowed by extraction with ethyl acetate
6. washThe organic layer was washed with saturated brine
7. customdried
8. concentrationconcentrated
9. customThe residue was purified by column chromatography on silica gel (ethyl acetate:hexane (volume ratio)=1:10 to 1:3)