[NH:1]1[CH:5]=[CH:4][CH:3]=[C:2]1/[CH:6]=[C:7]1\[C:8](=[O:22])[NH:9][C:10]2[C:15]\1=[CH:14][C:13]([C:16]#[C:17][Si](C)(C)C)=[CH:12][CH:11]=2.[C-]#N.[K+].C(=O)(O)[O-].[Na+]>C(O)C.O1CCCC1.O.[N+]([O-])([O-])=O.[Ag+]>[C:16]([C:13]1[CH:14]=[C:15]2[C:10](=[CH:11][CH:12]=1)[NH:9][C:8](=[O:22])/[C:7]/2=[CH:6]\[C:2]1[NH:1][CH:5]=[CH:4][CH:3]=1)#[CH:17]To a solution of (Z)-1,3-dihydro-3-[(1H-pyrrol-2-yl)methylene]-5-(trimethylsilyl)ethynyl-2H-indol-2-one (940 mg, 3.1 mmol) (from Example 81 above) in 50 mL ethanol and 15 mL tetrahydrofuran (Fisher Scientific) was added dropwise a solution of silver nitrate (1.17 g, 6.89 mmol) in 5 mL water and 15 mL ethanol, during which time a precipitate formed. The mixture was stirred at room temperature for 45 minutes, after which a solution of potassium cyanide (2.18 g, 33.47 mmol) in 8 mL of water was added and the precipitated dissolved. To the solution was then added 50 mL of a saturated aqueous sodium bicarbonate solution followed by 500 mL of water. The product was then filtered off and dried to give (Z)-1,3-dihydro-5-ethynyl-3-[(1H-pyrrol-2-yl)methylene]-2H-indol-2-one (yield 700 mg, 96%), which was recrystallized from EtOAc/Hex to yield 540 mg of the product as yellow crystals.
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