反应详情

Methylmagnesium chloride (3M solution in tetrahydrofuran; 5.7 ml) was added under nitrogen to a stirred solution of 4-chloro-N-methoxy-N-methylbenzo[b]thiophene-2-carboxamide (4 g; prepared in a manner similar to that described in Example 18) in tetrahydrofuran (120 ml) then the mixture was allowed to stand at ambient temperature for 30 minutes, heated under reflux for 30 minutes and allowed to stand at ambient temperature for 30 minutes. Further methylmagnesium chloride (3M solution in tetrahydrofuran; 2.0 ml) was added and the mixture was allowed to stand at ambient temperature for 2 hours. Further methylmagnesium chloride (3M solution in tetrahydrofuran; 2.0 ml) was added and the mixture was allowed to stand at ambient temperature for 30 minutes. Water (200 ml) and 5M hydrochloric acid (15 ml) were added and the product was extracted into dichloromethane (3×80 ml). The combined extracts were dried (MgSO4) and the solvents were removed in vacuo. The residue was purified by column chromatography over silica using dichloromethane as eluant. Appropriate fractions were combined and the solvents removed in vacuo to leave 1-(4-chloro-benzo[b]thiophen-2-yl]ethan-1-one (1.8 g) as an off-white solid, m.p. 113-115° C.

1. customprepared in a manner similar to
2. temperatureheated
3. temperatureunder reflux for 30 minutes
4. waitto stand at ambient temperature for 30 minutes
5. waitto stand at ambient temperature for 2 hours
6. waitto stand at ambient temperature for 30 minutes
7. extractionthe product was extracted into dichloromethane (3×80 ml)
8. dry with materialThe combined extracts were dried (MgSO4)
9. customthe solvents were removed in vacuo
10. customThe residue was purified by column chromatography over silica
11. customthe solvents removed in vacuo