反应详情

For the preparation of the preferred aryl alkyl ketones a Friedel-Crafts reaction can be used, e.g., to effect reaction according to the following general format ##STR7## wherein R" is the residue of the desired aryl (Ar) group and R1 is the residue of the carboxylic acyl halide. For example, the 6-methoxy-2-naphthyl propiophenone can be prepared by reacting 6-methoxynaphthalene with propionyl chloride in the presence of aluminum chloride in methylene chloride. The resulting 6-methoxy-2-naphthyl ethyl ketone is converted to the ketal starting material for this process by reacting it with trimethyl orthoformate in the presence of acid. The 3-phenoxyphenyl ethyl ketone ketal can be prepared by reacting 3-hydroxyphenyl ethyl ketone with phenyl bromide in the presence of potassium carbonate to form 3-phenoxyphenyl ethyl ketone and then reacting this ketone with trimethylorthoformate to form the ketal. The ketal of 2-fluoro-4-biphenylyl ethyl ketone is formed by reacting 2-fluoro-4-biphenylyl ethyl ketone with trimethylorthoformate to form the ketal. The 2-fluoro-4-biphenylyl ethyl ketone can be prepared from 4-bromopropiophenone via 4'-bromo-3'-nitropropiophenone (see Chemical Abstracts, 61, p. 8232g), 4-propionyl-2-nitrobiphenyl (Ullman reaction), 4-propionyl-2-aminobiphenyl (reduction) and finally the Schiemann Reaction. See U.S. Pat. No. 3,793,457, Example 1 for a similar synthesis of 2-fluoro-4-biphenyl methyl ketone. The difluorobiphenyl ketone can be prepared by reacting 4-cyano-2,2'-difluorobiphenyl with ethyl magnesium bromide to form the di-fluoro biphenylyl ethyl ketone. See U.S. Pat. No. 3,755,427. This ketone can be converted to the ketal by the procedure described above.

1. customa Friedel-Crafts reaction
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