The mixture of intermediate 2 (1 mmol), potassium carbonate (10 mmol) and isatins 3 (0.5 mmol) in DMF (10 mL) was stirred at room temperature overnight. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel chromatography eluted with PE:EA=1:2 to give the key intermediates 4a,b. To a mixture of intermediates 4a,b (1 mmol) in water (10 mL) and THF (50 mL), the requested amine hydrochloride (5 mmol) was added. The mixture was stirred at 50 oC for 12 h. After cooling to room temperature, the mixture was extracted with EA (100 mL*2). The combined organic layers were washed with H2O (100 mL*2) and brine (100 mL) in sequence, and dried over Na2SO4. After filtration, the filtrate was concentrated under reduced pressure to give a residue which was purified by silica gel chromatography eluted with PE:EA=1:2 to give the homonuclear isatin dimers 5a-d. A mixture of 5-methylisatin 6 (1 mmol), potassium carbonate (5 mmol) and methoxyamine or ethoxyamine hydrochloride (1.2 mmol) in a mixture of water (5 mL) and THF (30 mL) was stirred at 50 oC for 12 h. After cooling to room temperature, the mixture was extracted with EA (30 mL*2). The combined organic layers were washed with H2O (20 mL*2) and brine (20 mL) in sequence, dried over Na2SO4, filtrated, and concentrated under reduced pressure. The crude intermediates 7 were obtained as a yellow solid which were used directly without further purification. The mixture of intermediate 2 (2 mmol), potassium carbonate (10 mmol) and 5-fuloroisatin 8 (1 mmol) in DMF (10 mL) was stirred at room temperature overnight. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel chromatography eluted with PE:EA=1:2 to give the intermediates 9. A mixture of intermediate 9 (1 mmol), intermediate 7 (1 mmol) and potassium carbonate (10 mmol) in DMF (10 mL) was stirred at room temperature for 2 days. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel chromatography eluted with PE:EA=1:2 to give the desired heteronuclear isatin dimers 10a,b. To a mixture of heteronuclear isatin dimers 10a,b (1 mmol) in water (10 mL) and THF (50 mL), methoxyamine or ethoxyamine hydrochloride (1.4 mmol) was added. The mixture was stirred at 50 oC for 12 h. After cooling to room temperature, the mixture was extracted with EA (100 mL*2). The combined organic layers were washed with H2O (100 mL*2) and brine (100 mL) in sequence, and dried over Na2SO4. After filtration, the filtrate was concentrated under reduced pressure to give a residue which was purified by silica gel chromatography eluted with PE:EA=1:2 to give the desired products 10c-f. 1