Reaction #70221

Reaction equation

ketone

2′-Bromo-5′-hydroxy-4′-methoxyacetophenone

compound 19

O-(4-Nitrobenzyl)hydroxylamine Hydrochloride

imidazole

ethyl acetate hexane

→

title compound

(E)-2′-Bromo-5′-hydroxy-4′-methoxyacetophenone O-4-Nitrobenzyl Oxime

Solvents

EtOH

Conditions

Workup

1. 1
   Temperatureat reflux for 2 h
2. 2
   Temperaturebefore being cooled
3. 3
   Concentrationconcentrated under reduced pressure
4. 4
   OtherThe ensuing residue was partitioned between CH2Cl2 (10 mL) and H2O (10 mL)
5. 5
   Extractionthe separated aqueous fraction extracted with CH2Cl2 (1×10 ml)
6. 6
   DryingThe combined organic fractions were then dried (MgSO4)
7. 7
   Filtrationfiltered
8. 8
   Concentrationconcentrated under reduced pressure
9. 9
   Otherto afford

Procedure

A magnetically stirred solution of ketone 39 (162 mg, 0.661 mmol) in EtOH (2.0 mL) was treated with compound 19 (271 mg, 1.32 mmol) and imidazole (68 mg, 0.999 mmol) then the resulting mixture stirred at reflux for 2 h before being cooled and concentrated under reduced pressure. The ensuing residue was partitioned between CH2Cl2 (10 mL) and H2O (10 mL) and the separated aqueous fraction extracted with CH2Cl2 (1×10 ml). The combined organic fractions were then dried (MgSO4), filtered and concentrated under reduced pressure. The resulting mixture was subjected to flash chromatography (15:85 v/v ethyl acetate/hexane) to afford a ca. 3:1 mixture of the E- and Z-isomeric foams of the title compound CP302108 (229 mg, 88%) as a pale-yellow solid, Rf 0.5 in 1:1 v/v ethyl acetate/hexane. Recrystallisation of this material (twice from isopropanol) afforded the major isomer, CP302108-major, as a pale-yellow solid, m.p. 136.8-138.4° C.

Source