[SH:1][C:2]1[NH:3][C:4]2[CH:10]=[C:9]([O:11][Si:12]([C:15]([CH3:18])([CH3:17])[CH3:16])([CH3:14])[CH3:13])[CH:8]=[CH:7][C:5]=2[N:6]=1.[H-].[Na+].[N+]([C:24]1[O:28][C:27]([CH:29]=[O:30])=[CH:26][CH:25]=1)([O-])=O.O>O1CCCC1>[C:15]([Si:12]([CH3:13])([CH3:14])[O:11][C:9]1[CH:8]=[CH:7][C:5]2[NH:6][C:2]([S:1][C:24]3[O:28][C:27]([CH:29]=[O:30])=[CH:26][CH:25]=3)=[N:3][C:4]=2[CH:10]=1)([CH3:18])([CH3:17])[CH3:16]Aldehyde intermediate preparation: A solution of 2-mercapto-5-(tert-butyl-dimethyl-silanyloxy)-benzimidazole (2.07 g, 7.38 mmol) in tetrahydrofuran (15 ml) is added dropwise to a mixture of sodium hydride (60% dispersion in mineral oil, 0.472 g, 11.8 mmol) and tetrahydrofuran (5 ml) at 0° C. The mixture is stirred at room temperature for 3 hours. A solution of 5-nitro-2-furaldehyde (1.04 g, 7.38 mmol) in tetrahydrofuran (10 ml) is then added dropwise over a 15 minute period and the mixture is stirred for 16 hours at room temperature. Water (10 ml) is then added and the reaction mixture is concentrated under reduced pressure. The residue is dissolved in a minimal volume of ethyl acetate and is filtered through a silica gel plug (20 ml) that is eluted with 500 ml of ethyl acetate. The organic filtrates are concentrated under reduced pressure and are purified on a silicagel column (120 g) eluted with a mixture of cyclohexane and ethyl acetate (7/3, v/v) to yield 1.4 g of 5-[5-(tert-butyl-dimethyl-silanyloxy)-1H-benzimidazol-2-ylsulfanyl]-furan-2-carbaldehyde as a brown oil. Yield=51%. Analytical LC/MS (method B): retention time=4.62 min., m/z=375.05 (positive ion mode).
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