[CH3:1][CH:2]1[CH2:10][C:9]2[C:4](=[CH:5][CH:6]=[CH:7][CH:8]=2)[NH:3]1.Cl.[N:12]([O-])=O.[Na+].C(=O)(O)[O-].[Na+].C(=O)([O-])[O-].[NH4+].[NH4+]>CO.O.[Zn]>[NH2:12][N:3]1[C:4]2[C:9](=[CH:8][CH:7]=[CH:6][CH:5]=2)[CH2:10][CH:2]1[CH3:1]
140 g of 2-methylindoline was dissolved in 1 liter of methanol. About 95 ml of concentrated hydrochloric acid was added and the solution was cooled to 15° C. Then a 25% solution of sodium nitrite (73 g) in water was added dropwise at 5°-10° C. The pH of the solution was adjusted to about 7.5 with sodium bicarbonate and 156 g of zinc dust was added to form a mixture thereof. Keeping the mixture at about 5° C., a solution of 264 g of ammonium carbonate in 1 liter of water was added over a period of about 1.5 hours. The mixture was then stirred at 5°-10° C., warmed to 40° C., and filtered. The residual was washed with toluene. The combined filtrate and washes were separated and the aqueous layer was discarded. The toluene was removed in vacuo and the residue recrystallized from heptane to give 1-amino-2-methylindoline. TLC test confirmed the identity of the product compound. (ANALTECH Silica Gel plate; chloroform/acetic acid:9/1).
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