| 摘要 |
1,8-Diethyl 1,3,4,9-tetrahydropyrano (3,4-b) indole 1-acetic acid of formula (I) is made by (a) reacting formic acid with a cpd. of formula (III), using 300-700% molar excess of formic acid as a 40-60% aq. soln., at 70-130 deg. C; (b) isolating (I) by chromatography and fractional crystallisation; and (c) recrystallising from isopropanol, chloroform or hexane.
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