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2.66 g (54.3 mmol) of sodium cyanide, 37.78 g (434.4 mmol) of manganese dioxide and 979 mg (16.3 mmol) of acetic acid were added to a solution of 3.35 g (10.9 mmol) of 3-(2,4-dimethoxy-5-formylphenyl)octanoic acid (prepared as described in Preparation 32) in 70 ml of methanol, and the resulting mixture was stirred for 4 hours. At the end of this time, the reaction mixture was acidified with 1 N aqueous hydrochloric acid and filtered using a Celite (trade mark) filter aid. The filtrate was then concentrated by evaporation under reduced pressure, and the concentrate was mixed with a small amount of water, after which it was extracted with ethyl acetate. The extract was washed with water and with a saturated aqueous solution of sodium chloride, in that order, after which it was dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure, and the resulting residue was purified by column chromatography through 100 g of silica gel, using a gradient elution method, with mixtures of ethyl acetate and methanol ranging from 50:0 to 50:3 by volume as the eluent, to give 3.25 g (yield 88%) of the title compound, melting at 106-107° C. (from ethyl acetate-hexane).

1. filtrationfiltered
2. filtrationfilter aid
3. concentrationThe filtrate was then concentrated by evaporation under reduced pressure
4. additionthe concentrate was mixed with a small amount of water
5. extractionafter which it was extracted with ethyl acetate
6. washThe extract was washed with water and with a saturated aqueous solution of sodium chloride, in that order
7. dry with materialafter which it was dried over anhydrous magnesium sulfate
8. customThe solvent was removed by distillation under reduced pressure
9. customthe resulting residue was purified by column chromatography through 100 g of silica gel
10. washa gradient elution method