The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 01, 1997
Filed:
Jun. 19, 1995
Kazuharu Tamazawa, Saitama, JP;
Tadao Kojima, Saitama, JP;
Hideki Arima, Tokyo, JP;
Yukiyasu Murakami, Saitama, JP;
Yasuo Isomura, Tokyo, JP;
Minoru Okada, Tokyo, JP;
Toichi Takenaka, Tokyo, JP;
Kiyoshi Takanobu, Saitama, JP;
Yamanouchi Pharmaceutical Co., Ltd., Tokyo, JP;
Abstract
A process is provided for producing diastereoisomer A or a pharmaceutically acceptable acid addition salt of 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-(1-benzylpyrrolidin-3-yl) ester 5-methyl ester which comprises subjecting a mixture of diastereoisomers A and B of 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-(1-benzylpyrrolidin-3-yl) ester 5-methyl ester to column chromatography using silica gel as a carrier and a mixture of ethyl acetate and acetic acid as an eluant, and then separating the acetate of diastereoisomer A from the eluate, or treating the acetate with a base, or further treating the resulting diastereoisomer A with a pharmaceutically acceptable acid.