反应详情

A modification of a procedure in the following reference herein incorporated by reference in its entirety, for all purposes as if fully set forth herein, was used: Boojamra, C. G.; Burow, K. M.; Thompson, L. A.; Ellman, J. A. J. Org. Chem., 1997, 62, 1240-1256. A solution of (NH4)2Fe(II)(SO4)2.6H2O (24.4 g, 63 mmol) in water (60 mL) was added to a stirred solution of 4-bromo-2-nitro-benzoic acid (2) (3.05 g, 12.45 mmol) in concentrated aqueous NH4OH (40 mL) at room temperature. The iron sulfate solution flask was washed with an additional portion of water (20 mL) which was added to the reaction. After 16 hours, the reaction had changed from a dark green solution to a rusty-brown mixture which was filtered through a plug of Celite and washed with concentrated aqueous NH4OH (80 mL) and water (4×80 mL). The combined aqueous fractions were acidified to pH 1-2 with aqueous concentrated HCl and extracted with EtOAc (4×500 mL). The organic fractions were evaporated under reduced pressure to a brown solid. The crude product was dissolved in EtOAc (300 mL), washed with water (40 mL), brine (40 mL), dried with Na2SO4, filtered, and concentrated to dryness giving 2.47 g of product (3) as a brown solid in 91% yield and >90% purity by HPLC.

1. washThe iron sulfate solution flask was washed with an additional portion of water (20 mL) which
2. additionwas added to the reaction
3. filtrationwas filtered through a plug of Celite
4. washwashed with concentrated aqueous NH4OH (80 mL) and water (4×80 mL)
5. extractionextracted with EtOAc (4×500 mL)
6. customThe organic fractions were evaporated under reduced pressure to a brown solid
7. dissolutionThe crude product was dissolved in EtOAc (300 mL)
8. washwashed with water (40 mL), brine (40 mL)
9. dry with materialdried with Na2SO4
10. filtrationfiltered
11. concentrationconcentrated to dryness