合成路线1

The reaction of N-tert-butylbenzenesulfonamide (I) with triisopropyl borate by means of BuLi in THF gives the boronic acid (II), which is condensed with 4-bromonitrobenzene (III) by means of palladium tetrakis(triphenylphosphine) to yield the N-tert-butyl-4'-nitrobiphenyl-2-sulfonamide (IV). The reduction of (IV) with H2 over Pd/C in methanol affords the biphenylamine (V), which is acylated with 3-(3-cyanophenyl)-5-(methoxycarbonylmethyl)-4,5-dihydroisoxazole-5-carboxylic acid (VI), by means of SOCl2 in acetonitrile affording the corresponding amide (VII). The reaction of (VII) with trifluoroacetic acid eliminates the tert-butyl protecting group providing intermediate (VIII). Finally, the cyano group of (VIII) is converted into amidino by reaction with HCl in chloroform/methanol and reaction of the intermediate imidate with ammonium acetate. Alternatively, biphenylamine (V) can also be obtained as follows: The reaction of 4-bromoaniline (IX) with tert-butoxycarbonyl anhydride in THF gives the corresponding carbamate (X), which is condensed with the boronic acid (II) by means of palladium tetrakis triphenylphosphine and deprotected with trifluoroacetic acid to afford the target intermediate (V).