The condensation of 3,4-methylenedioxybenzaldehyde (I) with 3,3-dimethyl-2-butanone (II) by means of NaOH in ethanol-water gives 4,4-dimethyl-1-[(3,4-methylenedioxy)phenyl]-1-penten-3-one (III), which is reduced with NaBH4 in methanol.
The synthesis of [14]-labeled stiripentol has been published: The reaction of 3,4-methylenedioxybromobenzene (I) with 14CO2 by means of butyllithium in ether gives 3,4-methylenedioxybenzoic acid (II), which is reduced with LiAlH4 to the corresponding benzyl alcohol (III). Oxidation of (III) with CrO3-pyridine affords the aldehyde (IV), which is condensed with methyl tert-butyl ketone (V) by means of NaOH in refluxing ethanol to give the labeled pentanone (VI). Finally, this compound is reduced to [14C]-labeled stiripentol with NaBH4 in methanol.