Synthesis
GENERAL STEPS: The synthesis of 4-chloroindoline from 4-chloroindole was carried out as follows: 4-chloroindole (20.0 g, 148 mmol) was dissolved in acetic acid (60 mL), followed by the addition of sodium cyanoborohydride (18.7 g, 296 mmol) in batches. The reaction mixture was stirred at room temperature for 2 hours. Upon completion of the reaction, the mixture was slowly poured into 1500 mL of a 2 M NaOH aqueous solution. The aqueous phase was extracted with dichloromethane (CH2Cl2) and the organic layers were combined. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate (MgSO4) and concentrated under reduced pressure to give 4-chloroindoline (20.0 g, 98% yield). The product was confirmed by 1H NMR (400MHz, CDCl3): δ3.08 (2H, triple peak, J=8.4Hz), 3.62 (2H, triple peak, J=8.4Hz), 6.62-6.66 (1H, multiple peaks), 6.78-6.83 (1H, multiple peaks), 6.90 (1H, double double peaks, J=7.6,0.4Hz).
References
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