Example 2: Preparation of 2-aminooxazole. To a tetrahydrofuran (THF, 60 mL) solution of cyanamide (19.8 mL, 50% w/w aqueous solution, 0.25 mol) was added a 24 mL aqueous solution of 2-hydroxyacetaldehyde (15 g, 0.25 mol). The reaction mixture was treated with 2 M aqueous sodium hydroxide (25.2 mL, 0.05 mol) at 0 °C. The mixture was slowly warmed to room temperature and stirred continuously for 24 hours. Upon completion of the reaction, the volatile solvent (THF) was removed by distillation under reduced pressure. The remaining aqueous solution was extracted with ethyl acetate (4 × 200 mL). The organic phases were combined, dried with anhydrous sodium sulfate, and subsequently concentrated under reduced pressure to give 14.968 g (71.3% yield) of white solid product. The product was characterized by 400 MHz 1H NMR (CDCl3): δ 7.13 (s, 1H), 6.74 (s, 1H), 5.26 (br.s, 2H). Elemental analysis calculated values (C3H4N2O): C 42.86%, H 4.80%, N 33.32%; measured values: C 43.01%, H 4.87%, N 33.11%.
