General procedure for the synthesis of tert-butyl (3-formylphenyl)-carbamate from tert-butyl (3-(hydroxymethyl)phenyl)carbamate: activated manganese dioxide (7.8 g, 90 mmol) was added to a solution of dichloromethane (50 mL) containing 3-(tert-butoxycarbonylamino)-benzyl alcohol (2.0 g, 9.0 mmol). The resulting suspension was stirred and reacted at room temperature for 16 hours. Upon completion of the reaction, the mixture was filtered through a diatomaceous earth pad and the filtrate was concentrated under reduced pressure to give 1.7 g (85% yield) of the target product. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 9.97 (s, 1H), 7.92 (t, J = 1.8 Hz, 1H), 7.63 (dd, J = 8.0,1.1 Hz, 1H), 7.55 (ddd, J = 7.6,1.4,1.1 Hz, 1H), 7.44 (t, J = 7.6 Hz, 1H), and 1.53 (s, 9H).
