Fig. 5

Controlled stepwise reductive methylation. a Example showing fluorescent compound^{i, ii, iii}. b Selectivity towards mono-methylation^iv. ^aReaction conditions a: ⁱ0.5 mmol of 49, 50 mg Fe₂O₃/NGr@C (5 mol% Fe), 2 mmol paraformaldehyde, 1 mmol Na₂CO₃, 2 mL DMSO-water (1:1), 130 °C, 8 h. (b): ⁱⁱ0.5 mmol of 49, 50 mg Fe₂O₃/NGr@C (5 mol% Fe), 3.2 mmol paraformaldehyde, 1 mmol Na₂CO₃, 2 mL DMSO-water (1:1), 130 °C, 18 h. ⁱⁱⁱ0.5 mmol of 49, Fe₂O₃/NGr@C (5 mol% Fe), 10 mmol paraformaldehyde, 1 mmol Na₂CO₃, 2 mL DMSO-water (1:1), 130 °C, 30 h. ^ivReaction conditions of (B): 0.5 mmol nitroarene, 50 mg Fe₂O₃/NGr@C (5 mol% Fe), 3.2 mmol paraformaldehyde, 1 mmol Na₂CO₃, 2 mL DMSO-water (1:1), 130 °C, 18 h. All are isolated yields