反应详情

3-Ethoxy-cyclopent-2-enone (Intermediate NINE1) (commercially available from Aldrich) (10.0 g, 77.6 mmol) in carbon tetrachloride (15 mL) at 0° C. was treated with NBS (15.3 g, ˜85 mmol) added portion-wise over 30 m. After 1 h at 0° C. the mixture was partitioned between CH2Cl2 and saturated NaHCO3. The aqueous layer was extracted with CH2Cl2. The pooled organic layers were washed with H2O (2×) and dried over MgSO4. The mixture was filtered and evaporated to dryness. The solid was recrystallized from pentane:ether to give 13.3 g of 2-bromo-3-ethoxy-cyclopent-2-enone (Intermediate NINE2).

1. additionadded portion-wise over 30 m
2. customAfter 1 h at 0° C. the mixture was partitioned between CH2Cl2 and saturated NaHCO3
3. extractionThe aqueous layer was extracted with CH2Cl2
4. washThe pooled organic layers were washed with H2O (2×)
5. dry with materialdried over MgSO4
6. filtrationThe mixture was filtered
7. customevaporated to dryness
8. customThe solid was recrystallized from pentane