Ammonium Hydroxide → (Z)-4,5-diamino-1,3-dihydro-3-[(1H-pyrrol-2-yl)methylene]-2H-indol-2-one

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Reaction Steps

(Z)-4-Azido-1,3-dihydro-5-nitro-3-[(1H-pyrrol-2-yl)methylene]-2H-indol-2-one (340 mg, 1.15 mmol)(from Example 11) was dissolved in THF at rt (30 mL). Ammonium hydroxide was added (0.36 ml), followed by a catalytic amount of poisoned platinum on carbon (5% Pt/C•½S, 50 mg) (Engelhard Industries). The reaction mixture was hydrogenated in a Parr bomb under 50 psi of hydrogen for 2.5 h. The mixture was filtered through a cake of Celite®, and the cake was washed twice with THF. The hydrogenation was repeated with a fresh batch of catalyst, solvent and ammonium hydroxide (50 psi, 2 h). After filtration through Celite®, the mixture was concentrated under reduced pressure. The crude material was purified by flash chromatography on Silica Gel (230-400 mesh, eluted with 75% ethyl acetate in hexanes) to yield (Z)-4,5-diamino-1,3-dihydro-3-[(1H-pyrrol-2-yl)methylene]-2H-indol-2-one. (Yield 160 mg, 58%).

Provenance & Evidence