反应详情

4-Bromobenzamide (5.3 g) and dimethylformamide dimethoxyacetal (35 ml) were heated together at 125° C. for 2 h. The reaction was allowed to cool to rt and the liquid evaporated to give a pale yellow solid. Hydroxylamine hydrochloride (2.2 g) in 1N NaOH solution (36 ml) was added, followed by dioxane (36 ml) then AcOH (48 ml). The reaction mixture was stirred at rt for 30 min then heated at 90° C. for 3 h. The reaction was allowed to cool to rt and saturated aqueous K2CO3 solution (100 ml) was added followed by DCM (200 ml) before filtering. The organic phase was separated from the mixture, then saturated brine (100 ml) was added and the aqueous phase was extracted into EtOAc (200 ml). The combined organic phases were dried (Na2SO4) and evaporated to give a brown solid. The crude product was purified by column chromatography (silica gel, step gradient 10-50% EtOAc in hexane) to give the title compound (D41) as a white solid (2.9 g). LCMS electrospray (+ve) 240 (MH+).

1. customthe liquid evaporated
2. customto give a pale yellow solid
3. temperaturethen heated at 90° C. for 3 h
4. temperatureto cool to rt
5. filtrationbefore filtering
6. customThe organic phase was separated from the mixture
7. additionsaturated brine (100 ml) was added
8. extractionthe aqueous phase was extracted into EtOAc (200 ml)
9. dry with materialThe combined organic phases were dried (Na2SO4)
10. customevaporated
11. customto give a brown solid
12. customThe crude product was purified by column chromatography (silica gel, step gradient 10-50% EtOAc in hexane)