The alkylation of isovanillin (I) with cyclopentyl bromide (II) and K2CO3 in DMF gives 3-(cyclopentyloxy)-4-methoxybenzaldehyde (III), which is methylated with MeLi in THF yielding the 1-phenylethanol (IV). The oxidation of (IV) with pyridinium dichromate (PDC) in dichloromethane affords the corresponding acetophenone (V), which is treated with NH2OH in pyridine to afford the oxime (VI). Finally, this oxime is treated with NaOCN and TFA in dichloromethane, or with chlorosulfonyl isocyanate in THF.