N′-(3,4-Difluoro-thiobenzoyl)-hydrazinecarboxylic acid tert-butyl ester (0.1 mmol) prepared as described in example 3 for N′-(4-fluoro-benzoyl)-hydrazinecarboxylic acid tert-butyl ester, is treated with TFA (1 mmol) in dry CH2Cl2 (1 mL) at room temperature for 30 minutes. Solvent is removed and the residue is dissolved in dry CH2Cl2 (1 mL). DIEA (0.57 mmol) is added to the solution and the mixture is treated with 3-(4-formyl-benzooxazol-2-yl)-benzoic acid methyl ester (0.064 mmol) in the presence of 4 Å molecular sieves. 2,4,6-Trifluorobenzoyl chloride (0.15 mmol) is added after 5 minutes. The mixture is kept at room temperature for 16 hours and purified by preparative HPLC (20-100% MeCN/H2O) to yield 3-{4-[5-(3,4-difluoro-phenyl)-3-(2,4,6-trifluoro-benzoyl)-2,3-dihydro-[1,3,4]thiadiazol-2-yl]-benzooxazol-2-yl}-benzoic acid methyl ester. LC/MS (ES+): (M+1) 610.0, (M+Na) 632.0.
