Method for the preparation of 5-carboxyphthalide
AssigneeH. Lundbeck A/S
InventorsHans Petersen, Poul Dahlberg Nielsen
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Abstract
5-carboxyphthalide is obtained with very high purity and in high yields by a convenient process comprising reaction of terephthalic acid 1 with paraformaldehyde HO(CH2)nH in oleum.
Claims2
In a method of preparing citalopram by reacting 5-cyanophthalide with 4-fluorophenyl magnesium halide and N,N-dimethylaminopropyl magnesium halogenide, and subjecting the resulting dicarbinol compound to a ring closure reaction, wherein said 5-cyanophthalide is formed by reacting 5-carboxyphthalide with a dehydrating agent and sulfonamide of the formula H2N—SO2-R wherein R is NH2, alkyloxy, optionally substituted phenyloxy or substituted phenyl to form 5-cyanophthalide, the improvement comprising forming 5-carboxyphthalide
- 5
- by reacting terephthalic acid
- 6
- with paraformaldehyde HO(CH2)nH in oleum.
A method of preparing citalopram by reaction of 5-cyanophthalide, wherein said 5-cyanophthalide is formed by reacting 5-carboxyphthalide with a dehydrating agent and sulfonamide, and 5-carboxyphthalide
- 7
- is formed by reacting terephthalic acid
- 8
- with paraformaldehyde HO(CH2)nH wherein n is an integer from 8 to 100, in oleum.
Dependencies are inferred from the claim text.