[Br:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[CH2:8]C=O.[CH:11](OC)([O:14][CH3:15])[O:12][CH3:13].O.C1(C)C=CC(S(O)(=O)=O)=CC=1.[OH-].[Na+].[Cl-].[Na+].O>CO.C(OCC)C>[CH3:13][O:12][CH:11]([O:14][CH3:15])[CH2:8][C:3]1[CH:4]=[CH:5][CH:6]=[CH:7][C:2]=1[Br:1]To a solution of 10.0 grams (0.05 mole) of 2-(2-bromophenyl)acetaldehyde (from the above preparation and another similar preparation) in 50 milliliters of dry methanol, was added 50 milliliters of trimethyl orthoformate and 0.25 gram of p-toluenesulfonic acid monohydrate and the resulting mixture was heated at reflux temperature for 3.5 hours. At the end of this period, the reaction mixture was cooled and 100 milliliters of diethyl ether and 50 milliliters of a 1:1 solution of 50 percent aqueous sodium hydroxide/brine were added. The ether solution was mechanically separated, washed, dried and stripped on the rotary evaporator to obtain 2-(2-bromophenyl)acetaldehyde dimethylacetal intermediate as a yellow oil. The latter was distilled to obtain 10.5 grams (85 percent yield) of purified product as a clear oil, b.p. 65°-67° /0.2 mm.
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