3',4'-Bis(pivaloyloxy)propiophenone was first prepared as a mobile liquid (63.6 g.), in a similar manner to 3',4'-bis(pivaloyloxy)acetophenone in Example 1, starting from 3',4'-dihydroxypropiophenone (40 g.), pivaloylchloride (63.3 ml.) and triethylamine (73.2 ml.). This mobile liquid (40.1 g.) was then reacted with bromine (7.2 ml.) in a similar manner to that used in Example 1 to obtained 2-bromo-3',4'-bis(pivaloyloxy)acetophenone. The crude bromo compound thus obtained was purified by dry column chromatography on silica gel as described in Example 1 to give pure 2-bromo-3',4'-bis(pivaloyloxy)propiophenone as a solid (18.4 g.), m.p. 58°-60° C.
