4254-67-5

1-(4-(Benzyloxy)phenyl)-2-bromoethanone is an intermediate of Ractopamine Dimer Ether Dihydrochloride (R071420), which is an impurity of Ractopamine (R071400). A b-Adrenergic agonist. A repartitioning agent.

Obtained by reaction of bromine with 4-benzyloxyacetophenone in methanol in the presence of concentrated hydrochloric acid at 0–5° for 1 h, then at r.t. for another 1 h (90%).

General procedure for the synthesis of 2-bromo-4'-benzyloxyacetophenone from 1-(4-(benzyloxy)phenyl)ethanone: To a clarified solution of 1-(4-(benzyloxy)phenyl)ethanone (16.1 g, 71.2 mmol) in tetrahydrofuran (200 mL) at 0 °C, slowly add phenyltrimethylammonium tribromide (29.4 g, 78 mmol) dropwise to a tetrahydrofuran ( 150mL) solution. After completion of the reaction, the insoluble material was removed by filtration and washed with tetrahydrofuran. The filtrate was concentrated and the resulting yellow oil was purified by recrystallization from isopropanol. The final product was 2-bromo-4'-benzyloxyacetophenone with a yield of 17.99 g and 83%.

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