The hydrolysis of N-(4,5-dimethyl-3-isoxazolyl)carbamic acid tert-butyl ester (I) with HCl in dioxane gives the corresponding amine (II), which is condensed with 2-bromophenylsulfonyl chloride (III) by means of DMAP in pyridine to yield the sulfonamide (IV). The alkylation of (I) with 2-methoxyethoxymethyl chloride (V) and NaH in DMF affords the N,N-disubstituted sulfonamide (VI), which is treated with trimethyl borate (VII) and BuLi in THF to provide the boronate (VIII). The condensation of (VIII) with 2-bromo-5-(2-oxazolyl)benzaldehyde (IX) by means of palladium tetrakis(triphenylphosphine) in hot toluene/ethanol gives the biphenyl derivative (X), which is deprotected by means of HCl in refluxing ethanol/water to yield the sulfonamide (XI). The reductive amination of (XI) with methylamine and NaBH(OAc)3 in dichloromethane/HOAc affords the secondary amine (XII), which is finally acylated with 3,3-dimethylbutyryl chloride and TEA in dichloromethane to furnish the target diamide.