Process to prepare, 1,4-dihydropyridine intermediates and...

Details Process to prepare, 1,4-dihydropyridine intermediates and... Process to prepare, 1,4-dihydropyridine intermediates and...

2005-02-22

2005-02-22

Killos, Paul J. (Department: 1625)

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acid esters

C560S021000, C560S051000, C546S249000, C546S321000

Reexamination Certificate

active

06858747

ABSTRACT:
An improved catalyst is disclosed for a process involving the preparation of benzylidene intermediates useful in the preparation of 1,4-dihydropyridine compounds and derivatives thereof useful as medicines such as for example felodipine. This is accomplished by the condensation of an aldehyde and an acetoacetate in the presence of a novel catalyst system that includes a pyridyl carboxylic acid and a secondary amine. It has been found that through the use of the present invention the purity and yield of the desired isomer of the benzylidene intermediate can be maximized, thus avoiding the requirement of additional purification steps. The use of these intermediates can then be further reacted to form the required dihydropyridines, again having a very high purity and yield compared with the prior art.

REFERENCES:
patent: 4600778 (1986-07-01), Teller et al.
patent: 5310917 (1994-05-01), Auerbach
patent: 5977369 (1999-11-01), Desai et al.
patent: 549753 (1985-12-01), None
patent: WO 9807698 (1997-07-01), None
Cope, Arthur C.,Condensation Reactions. I. The Condensation of Ketones with Cyanoacetic Esters and the Mechanism of the Knoevenagel Reaction, Journal of the American Chemical Society, 1937, vol. 59, pp. 2327-2330.
Fener, Chen et al.,Synthesis of Calcium Antagonist. III. Synthesis of Felodipine, 1995, vol. 7, No. 2, pp. 154-157.

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