Citric Acid → 6-(7-Hydroxyheptyl)-7-(3-hydroxy-4-methyloct-1-enyl)-1,4-dioxaspiro[4,4]nonane

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Reaction Steps

6-(7-Hydroxyheptyl)-7-(4-methyl-3-oxooct-1-enyl)-1,4-dioxaspiro[4,4]nonane [1.0 g; prepared as hereinbefore described in Example 1 (v)] was dissolved in methanol (50 ml.) and added to aqueous sodium citrate solution (130 ml; 2% w/v). To this stirred solution, at -5° to 0° C., solid potassium borohydride (2.24 g.) was added portionwise at such a rate as to avoid undue effervescence and the reaction mixture was maintained at pH 8 by the occasional addition of aqueous citric acid solution (10% w/v). After the final addition of the potassium borohydride the reaction mixture was stirred at -5° to 0° C. and pH 8 for 90 minutes. Acetone (50 ml.) was then added, the solution was saturated with sodium chloride, and extracted with diethyl ether. The combined ether extracts were washed with a saturated solution of sodium chloride in hydrochloric acid (2 N) and saturated sodium chloride solution respectively, then dried over sodium sulphate. Removal of the solvent under reduced pressure gave crude 6-(7-hydroxyheptyl)-7-(3-hydroxy-4-methyloct-1-enyl)-1,4-dioxaspiro[4,4]nonane (0.6 g.), νmax 3400 cm-1, 1040 cm-1 , 970 cm-1, which was used in the next stage without further purification.

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