2-Methyltetrahydrofuran → 1-Amino-4-(tert-butoxycarbonylamino)pyridinium 2,4-dinitrophenolate

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Reaction Steps

To a 3 L four-necked flask equipped with an overhead stirrer, thermocouple and a condenser was charged with O-(2,4-dinitrophenyl)hydroxylamine (I-37) (248 g, 1245.5 mmol) and 2-MeTHF (1 L). To the stirred suspension at room temperature were added tert-butyl pyridin-4-ylcarbamate (254.6 g, 1245.5 mmol) and 2-MeTHF (1 L). The mixture was stirred at room temperature for 10 minutes and slowly heated to 40° C. (after 30 minutes the suspension became a solution at 30° C.). An exotherm was observed at 40° C. and the temperature reached 45° C. without heating. The mixture was cooled with a water bath to 40° C. and stirred at 40° C. for 4 hours. The mixture was further cooled to room temperature and stirred for 15 hours. The batch was filtered and the solid was washed with MTBE (2×200 mL) and air dried to give 1-amino-4-(tert-butoxycarbonylamino)pyridinium 2,4-dinitrophenolate (I-38) as a yellow solid. 1H NMR (500 MHz, DMSO) δ 10.90 (s, 1 H), 8.62 (s, 1 H), 8.54 (d, 2 H), 7.91 (d, 2 H), 7.85 (m, 3 H), 6.30 (d, 1 H), 1.46 (s, 9 H).

Provenance & Evidence