The reduction of 2,4-dichloro-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-one (I) with NaBH4 in methanol gives the corresponding alcohol (II), which is treated with refluxing SOCl2 to yield 2,4,5-trichloro-10,11-dihydro-5H-dibenzo[a,d]cycloheptene (III). Finally, this compound is condensed with imidazole (IV) in refluxing DMF and salified with nitric acid in isopropanol/diisopropyl ether.
A process useful for the industrial preparation of eberconazole has been reported: The Wittig condensation of 2-(methoxycarbonyl)benzyl(triphenyl)phosphonium bromide (I) with 3,5-dichlorobenzaldehyde (II) by means of NaH in DMF gives 2-[2-(3,5-dichlorophenyl)vinyl]benzoic acid methyl ester (III), which is hydrolyzed with NaOH in methanol to the corresponding free acid (IV). The hydrogenation of (IV) with H2 over Pd/C in methanol affords 2-[2-(3,5-dichlorophenyl)ethyl]benzoic acid (V), which is cyclized to 2,4-dichloro-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-one (VI) by means of polyphosphoric acid. The reduction of (VI) with NaBH4 yields the corresponding carbinol (VII), which is treated with SOCl2 affording the chloride (VIII). Finally, this compound is condensed with imidazole (IX) in refluxing DMF.