合成路线1

1) The reaction of 5-methylbenzofuran (I) with triisopropyl borate by means of butyllithium and tetramethylethylenediamine (TMEDA) in ethyl ether gives 5-methylbenzofuran-2-boronic acid (II), which is condensed with methyl 2-bromobenzoate (III) by means of tetrakis(triphenylphosphine)palladium yielding 2-(5-methylbenzofuran-2-yl)benzoic acid methyl ester (IV). The bromination of (IV) with Br2 in CCl4 affords 2-(3-bromo-5-methylbenzofuran-2-yl)benzoic acid methyl ester (V), which is hydrolyzed with NaOH in refluxing methanol to the corresponding benzoic acid (VI). The reaction of (VI) with diphenylphosphoryl azide (DPPA) and tert-butanol in dioxane gives N-[2-(3-bromo-5-methylbenzofuran-2-yl)phenyl]carbamic acid tert-butyl ester (VII), which is brominated with N-bromosuccinimide (NBS) and benzoyl peroxide to the corresponding bromomethyl derivative (VIII). The condensation of (VIII) with 4-cyclopropyl-2-ethylimidazole-5-carboxylic acid ethyl ester (IX) by means of K2CO3 in DMF affords 1-[3-bromo-2-[2-(tert-butoxycarbonylamino)phenyl]benzofuran-5-ylmethyl]-4-cyclopropyl-2-ethylimidazole-5-carboxylic acid ethyl ester (X), which is treated with trifluoroacetic acid to eliminate the carbamate group, yielding compound (XI) with a free amino group. Acylation of (XI) with trifluoromethanesulfonic anhydride in dichloromethane gives the sulfonamide (XII), which is treated with NaOH in hot aqueous methanol to hydrolyze the ethyl ester group and isolate the carboxylic acid (XIII). Finally, this compound is treated first with carbonyldiimidazole (CDI) in THF and then with ethanolic ammonia. 2) The intermediate imidazole (IX) is obtained by reaction of ethyl 3-cyclopropyl-3-oxopropanoate (XIV) with NaNO2 and acetic acid, followed by hydrogenation with H2 over Pt/C in ethanol to give ethyl 2-amino-3-cyclopropyl-3-oxopropanoate (XV), which is then cyclized with propionimidic acid ethyl ester (XVI) by means of triethylamine in ethanol.