合成路线1

Metallation of 1,4-dibromobenzene (I) followed by addition to hexafluoroacetone afforded the bis(trifluoromethyl)carbinol (II), which was subsequently protected as the trimethylsilylethoxymethyl ether (III). 3,4-Dihydroxybenzaldehyde (IV) was alkylated with either chlorodifluoromethane or methyl chlorodifluoroacetate to give the bis(difluoromethyl)ether (V). Addition of either the organolithium or Grignard reagent prepared from aryl bromide (III) to aldehyde (V) furnished the diaryl carbinol (VI), which was converted to chloride (VII) by treatment with SOCl2 and diisopropyl ethylamine. Selective carbomethoxylation of 3,4-dimethylpyridine (VIII) using dimethyl carbonate and LDA afforded (IX). Condensation of chloride (VII) with the lithium anion of (IX) yielded the triarylpropionate derivative (X). Ester group hydrolysis with LiOH, followed by acidification with NH4Cl, provided the decarboxylated compound (XI). After SEM group cleavage by treatment with tetrabutylammonium fluoride, the pyridine ring of the resulting (XII) was finally oxidized to the target N-oxide.