[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[N:12](C(C)OCC)[CH:11]=[N:10][C:9]=2[C:18]2[CH:23]=[CH:22][C:21]([S:24][CH3:25])=[CH:20][CH:19]=2)=[CH:4][CH:3]=1.CN(C)CCN(C)C.C([Li])CCC.CN(C)[CH:41]=[O:42]>O1CCCC1>[F:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[NH:12][C:11]([CH:41]=[O:42])=[N:10][C:9]=2[C:18]2[CH:23]=[CH:22][C:21]([S:24][CH3:25])=[CH:20][CH:19]=2)=[CH:6][CH:7]=1A solution of the compound from step 2 (500 mg, 1.4 mmol) and tetramethylethylenediamine (TMEDA) (186 mg, 1.6 mmol) in tetrahydrofuran (8 ml) was cooled to -70° C. under an argon atmosphere. n-Butyllithium (1.2 ml of 1.6M solution in hexane, 1.9 mmol) was added and the solution stirred at -70° C. for 15 minutes. Dimethylformamide (DMF) (140 mg, 1.9 mmol) was added and the solution was warmed to 0° C. The reaction was quenched by the addition of saturated NaHCO3 solution (2 ml) and extracted with diethyl ether. The organic phase was separated and dried (Na2SO4). The drying agent was filtered and the filtrate concentrated in vacuo. The residue was treated with 2N HCl (5 ml) in EtOH (10 ml) at room temperature for 24 hours. The reaction solution was made basic with NaHCO3, diluted with water (20 ml) and extracted with methylene chloride. After evaporation, the residue was chromatographed on silica gel, eluting with toluene/methanol (90/10), to give 350 mg (70%) of titled compound which was used immediately without further purification.
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