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:
Jun. 28, 1988
Filed:
Aug. 02, 1985
Adrian Waldner, Allschwil, CH;
Ciba-Geigy Corporation, Ardsley, NY (US);
Abstract
A process for producing pyridine-2,3-dicarboxylic acid derivatives of the formula ##STR1## is described. The process is based on the cleavage of HNR.sub.10 R.sub.11 from 1-amino-1,2,3,4-tetrahydropyridine-2,3-dicarboxylic acid derivatives of the formula II ##STR2## to give 1,4-dihydropyridine-2,3-dicarboxylic acid derivatives of the formula III ##STR3## and subsequent oxidation of these compounds to obtain pyridine-2,3-dicarboxylic acid derivatives of the formula I. According to one variant of the process, the 1,4-dihydropyridine-2,3-dicarboxylic acid derivatives of the formula III are obtained directly, without isolation of the intermediately formed 1-amino-1,2,3,4-tetrahydropyridine-2,3-dicarboxylic acid derivatives of the formula II, by reaction of .alpha.,.beta.-unsaturated hydrazones of the formula IV ##STR4## with ethene-1,2-dicarboxylic acid derivatives of the formula V ##STR5## and subsequently oxidized to pyridine-2,3-dicarboxylic acid derivatives of the formula I. In the above formulae, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.10 and R.sub.11 have the meanings defined in claim 1. The pyridine-2,3-dicarboxylic acid derivatives of the formula I are intermediates for producing herbicidal active substances.