The esterification of 2,4-dichloromandelic acid (I) with methanol and sulfuric acid gives the corresponding methyl ester (II), which by treatment with NH3 in methanol yields 2,4-dichloromandelamide (III). The alkylation of (III) with allyl chloride (IV) and NaH in THF affords 2-allyloxy-2-(2,4-dichlorophenyl)acetamide (V), which is hydrolyzed with refluxing aqueous HCl giving 2-allyloxy-2-(2,4-dichlorophenyl)acetic acid (VI). The reduction of (VI) with LiAlH4 in refluxing ether yields 2-allyloxy-2-(2,4-dichlorophenyl)ethanol (VII), which is esterified with methanesulfonyl chloride in pyridine to afford 2-allyloxy-2-(2,4-dichlorophenyl) ethanol methanesulfonate (VIII). Finally, this compound is condensed with 1H-imidazole (IX) in refluxing DMF.
The bromination of 2,4-dichloroacetophenone (X) with Br2 in refluxing methanol gives 2,4-dichlorophenacyl bromide (XI), which is condensed with 1H-imidazole (IX) in methanol to yield 2,4-dichloro-alpha-(1-imidazolyl)acetophenone (XII). The reduction of (XII) with NaBH4 in refluxing methanol affords 1-(2,4-chlorophenyl)-2-(1-imidazolyl)ethanol (XIII), which is finally alkylated with allyl chloride (IV) and NaH in refluxing DMF.