Reaktion #2270851

Reaktionsgleichung

3-(Benzo[b]thiophen-5-yl)-2-bromo-5,6-dihydroimidazo[2,1-b]thiazole hydrobromide

ethylmagnesium chloride

Dimethylformamide

→

3-(benzo[b]thiophen-5-yl)-5,6-dihydroimidazo[2,1-b]thiazole-2-carboxaldehyde

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGthe mixture was stirred at <15° C. for 20 minutes and at ambient temperature for 1 hour
2. 2
   Sonstigeit was quenched by the addition of saturated aqueous ammonium chloride solution (10 ml) and water (5 ml)
3. 3
   workup.ADDITIONEthyl acetate (30 ml) was added
4. 4
   workup.STIRRINGthe mixture was stirred at ambient temperature for 18 hours
5. 5
   Sonstigethe organic layer was separated
6. 6
   Sonstigefurther product was isolated from the aqueous layer by extraction into ethyl acetate (2×15 ml)
7. 7
   WaschenThe combined ethyl acetate solutions were washed with water (2×30 ml) and saturated aqueous sodium chloride solution (35 ml)
8. 8
   Trocknenthey were dried (MgSO4)
9. 9
   Sonstigethe solvents were removed in vacuo
10. 10
    SonstigeThe residue was purified by flash chromatography over silica using
11. 11
    workup.ADDITIONa 9:1 mixture of ethyl acetate and methanol as eluant
12. 12
    Sonstigethe solvents were removed in vacuo

Vorschrift

3-(Benzo[b]thiophen-5-yl)-2-bromo-5,6-dihydroimidazo[2,1-b]thiazole hydrobromide (1.9 g) was added in portions under nitrogen at 0-5° C. to a stirred solution of ethylmagnesium chloride (2M solution in ether; 6.8 ml) in tetrahydrofuran (30 ml), then the mixture was stirred at this temperature for 20 minutes. Dimethylformamide (1.5 ml) was added at <15° C., the mixture was stirred at <15° C. for 20 minutes and at ambient temperature for 1 hour, then it was quenched by the addition of saturated aqueous ammonium chloride solution (10 ml) and water (5 ml). Ethyl acetate (30 ml) was added, the mixture was stirred at ambient temperature for 18 hours, then the organic layer was separated and further product was isolated from the aqueous layer by extraction into ethyl acetate (2×15 ml). The combined ethyl acetate solutions were washed with water (2×30 ml) and saturated aqueous sodium chloride solution (35 ml), then they were dried (MgSO4) and the solvents were removed in vacuo. The residue was purified by flash chromatography over silica using a 9:1 mixture of ethyl acetate and methanol as eluant. Appropriate fractions were combined and the solvents were removed in vacuo to give 3-(benzo[b]thiophen-5-yl)-5,6-dihydroimidazo[2,1-b]thiazole-2-carboxaldehyde (0.7 g) as a yellow solid, m.p. 146° C.

Quelle