To a stirring suspension of 49 mg (0.10 mmol) of acetic acid 2-[3-(3-azido-4-methyl-benzoylamino)-5-methanesulfonylamino-4-methoxy-phenyl]-2-methyl-propyl ester in 1 mL of EtOH was added 4N NaOH dropwise until the solids dissolved. 2-Cyclopropyl-5-ethynyl-1-methyl-1H-imidazole (125 mg, 0.855 mmol) was added followed by 20 mg (0.1 mmol) of sodium ascorbate in water. The mixture was stirred under N2 and CuSO4 (0.1 M; 0.1 mL, 0.010 mmol) was added. The suspension was stirred overnight, then was was diluted with half-saturated NH4Cl, and extracted with EtOAc. The extract was washed with brine, and the washes were extract once more wtih EtOAc. The extracts were combined, dried with Na2SO4, filtered, and concentrated. Chromatography (0–4% MeOH (0.5% NH4OH) in CH2Cl2) provided the desired product with a slight blue-green color. The product was then redissolved in EtOAc and washed again with NH4Cl with a few drops of NH4OH added. The aqueous layer became blue, and the organic layer was washed once more with NH4Cl/NH4OH, and once with brine. The organic layer was then dried with Na2SO4, filtered, and concentrated to provide Example 133 (83 mg). ESI MS m/z 594 [C29H35N7O5S+H]+.
