Bromine → 2-Acetoxy-5-(2-bromoacetyl)benzyl acetate

Participants

Reaction Steps

A solution of bromine (7.1 g.) in chloroform (20 ml.) was added dropwise to a stirred solution of 3'-acetoxymethyl-4'-acetoxyacetophenone (11.0 g.) in chloroform (150 ml.) at room temperature. After completion of the addition, the solution was washed with water (2×150 ml.) and brine (100 ml.). The organic phase was dried (MgSO4), filtered and evaporated to give 3'-acetoxymethyl-4'-acetoxy-2-bromoacetophenone (10.0 g.) which was judged to be sufficiently pure by IR and TLC [SiO2 ; 1:1 v/v EtOAc/petrol (60°-80° C.)] for use without further purification or characterisation. A solution of 3'-acetoxymethyl-4'-acetoxy-2-bromoacetophenone (10.0 g.) in dimethylsulphoxide (150 ml.) was stirred at room temperature for 48 hours. The solution was then poured into ice-water (500 ml.) and extracted with ethyl acetate (3×200 ml.). The organic layers were combined, dried (MgSO4) filtered. The solvent was removed by evaporation to give 3'-acetoxymethyl- 4'-acetoxy-phenylglyoxal hydrate as a yellow oil (6.5 g. 81%). The glyoxal derivative had a satisfactory IR spectrum and was judged pure by TLC (SiO2 : EtOAc) and was therefore used without full characterisation or isolation.

Provenance & Evidence