[C:1]([Si:5]([CH3:18])([CH3:17])[O:6][C:7]1[CH:8]=[CH:9][C:10]([N+:14]([O-])=O)=[C:11]([CH:13]=1)[NH2:12])([CH3:4])([CH3:3])[CH3:2]>CO.[Pd]>[C:1]([Si:5]([CH3:18])([CH3:17])[O:6][C:7]1[CH:8]=[CH:9][C:10]([NH2:14])=[C:11]([NH2:12])[CH:13]=1)([CH3:4])([CH3:3])[CH3:2]A solution of 5-(tert-butyl-dimethyl-silanyloxy)-2-nitro-aniline (1.9 g, 7.08 mmol) in methanol (40 ml) is introduced in a hydrogenation vessel with 10% palladium on carbon catalyst (0.226 g). The reaction mixture is heated at 80° C. for 3 hours under an hydrogen atmosphere (P=1 bar). The reaction mixture is then filtered on Celite® and concentrated under reduced pressure. The residue is dissolved in 10 ml of ethyl acetate and filtered through a silica gel plug (40 ml) that is washed with 600 ml of ethyl acetate. The organic filtrates are concentrated under vacuum to yield 2.55 g of 4-(tert-butyl-dimethyl-silanyloxy)-ortho-phenylenediamine used without further purification in the following step. Analytical LC/MS (method B): retention time=3.12 min., m/z=239.15 (positive ion mode).
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