Reaktion #74555

Reaktionsgleichung

HCl

5-amino-1,2,4-thiadiazole

2,4-dimethoxybenzaldehyde

NaOH

NaBH4

→

title compound

Ausbeute 49.1%

(2,4-dimethoxy-benzyl)-[1,2,4]thiadiazol-5-yl-amine N-(2,4-dimethoxybenzyl)-1,2,4-thiadiazol-5-amine

Ausbeute 49.1%

Lösungsmittel

toluene

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwas refluxed under Dean and Stark conditions for 2 hours
2. 2
   SonstigeThe reaction mixture was evaporated
3. 3
   workup.ADDITIONafter each addition), and the reaction
4. 4
   workup.WAITwas left
5. 5
   SonstigeThe bulk of the methanol was evaporated
6. 6
   workup.ADDITIONwater (20 ml) added
7. 7
   Extraktionextracted with ethyl acetate (2×30 ml)
8. 8
   WaschenThe combined organic was washed brine (20 ml)
9. 9
   Sonstigedried
10. 10
    Sonstigeevaporated
11. 11
    SonstigeThe residue was purified by silica gel column chromatography (ISCO™ column 120 g; ethyl acetate:heptane 25:75 to 60:40)
12. 12
    Sonstigeto furnish a semi-solid residue that
13. 13
    Sonstigewas re-evaporated from heptane
14. 14
    workup.ADDITION2-3 ml tBuOMe was added
15. 15
    Filtration2-3 ml heptane, the solid filtered off
16. 16
    Waschenwashed with heptane
17. 17
    Sonstigedried

Vorschrift

A mixture of 5-amino-1,2,4-thiadiazole (1 g; 9.89 mmol) and 2,4-dimethoxybenzaldehyde (1.81 g; 10.9 mmol) in toluene (30 ml) was refluxed under Dean and Stark conditions for 2 hours. The reaction mixture was evaporated, the residue taken up in methanol (25 ml), NaBH4 (600 mg; 15.9 mmol) added carefully in small portions (vigorous effervescence after each addition), and the reaction was left stirring overnight at ambient temperature. Aqueous HCl (2M, 1 ml) was added followed by aqueous NaOH (2M, 10 ml). The bulk of the methanol was evaporated, water (20 ml) added and extracted with ethyl acetate (2×30 ml). The combined organic was washed brine (20 ml), dried, and evaporated. The residue was purified by silica gel column chromatography (ISCO™ column 120 g; ethyl acetate:heptane 25:75 to 60:40) to furnish a semi-solid residue that was re-evaporated from heptane. 2-3 ml tBuOMe was added, then 2-3 ml heptane, the solid filtered off, washed with heptane and dried to afford 1.22 g of the title compound.

Quelle