General procedure for the synthesis of tert-butyl (4-methylthiophen-2-yl)carbamate from 4-methyl-2-thiophenecarboxylate (1.00 g, 7.03 mmol) and tert-butanol: 4-methyl-2-thiophenecarboxylate (1.00 g, 7.03 mmol), diphenylphosphoryl azide (1.94 g, 7.03 mmol) and triethylamine (0.98 mL. 7.03 mmol) were dissolved in tert-butanol (20 mL) and heated to reflux for 5 hours. Upon completion of the reaction, confirmation was monitored by thin layer chromatography (unfolding agent: dichloromethane/hexane). The reaction mixture was cooled to room temperature, poured into water and extracted with ether (3 x 20 mL). The ether extracts were combined, washed with saturated saline, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give a beige solid. Purification by silica gel column chromatography (eluent: hexane/dichloromethane) afforded the target compound tert-butyl (4-methylthiophen-2-yl)carbamate (0.96 g, yield 64%) as a white solid.1H-NMR (400 MHz, DMSO-d6) δ 6.42 (s, 1H), 6.35 (d, 1H), 1.46 (s, 9H).
