反应详情

Methoxyacetic acid 360 mg, 3.99 mmol), 4-ethyl-3-thiosemicarbazide (581 mg, 4.87 mmol), diisopropylcarbodiimide (615 mg, 4.87 mmol) and hydroxybenzotriazole (69.6 mg, 0.51 mmol) were mixed in dimethylformamide (10 ml) and stirred under argon at ambient temperatures for 19 h. After evaporation to dryness the crude was used directly in the next step. MS (ESI) m/z 192 (M+1). Step 2: 4-Ethyl-5-methoxymethyl-2,4-dihydro-[1,2,4]triazole-3-thione: N-Ethyl-2-(methoxyacetyl(hydrazinecarbothioamide (760 mg crude, 4 mmol) and sodium bicarbonate (560 mg, 6.6 mmol) were suspended in water (15 ml) and refluxed for 5 h. After cooling and filtration the filtrate was acidified with concentrated hydrochloric acid, followed by extraction with ethyl acetate. After evaporation to dryness the crude was recrystallized in ethyl acetate/heptane. Filtration and recrystallization of the mother liquor gave a combined yield of 325 mg (47%) of the title compound. 1H NMR (CDCl3), δ (ppm): 4.47 (s, 2H), 4.13 (q, 2H), 3.37 (s, 3H), 1.38 (t, 3H).

1. customAfter evaporation to dryness the crude
2. temperaturerefluxed for 5 h
3. temperatureAfter cooling
4. filtrationfiltration the filtrate
5. extractionfollowed by extraction with ethyl acetate
6. customAfter evaporation to dryness the crude
7. customwas recrystallized in ethyl acetate/heptane
8. filtrationFiltration and recrystallization of the mother liquor