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. 07, 1992
Filed:
Nov. 02, 1990
Applicant:
Inventors:
Ralf Devant, Darmstadt, DE;
Rolf Gericke, Seeheim, DE;
Assignee:
Merck Patent Gesellschaft Mit Beschrankter Haftung, Darmstadt, DE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C07D / ;
U.S. Cl.
CPC ...
549387 ;
Abstract
The invention relates to a process for the resolution of enantiomers of 3,4-epoxy-3,4-dihydro-2,2-dimethyl-3-R-2H-1-benzopyran-6-carbonitriles (I), in which R is H or CH.sub.3, characterized in that racemic I is dissolved in an inert solvent or solvent mixture together with a small amount of (-)-I [or (+)-I], the solution is seeded with (-)-I [or (+)-I], the precipitated (-)-I [or (+)-I] is isolated, further racemic I is dissolved in the filtrate, seeded with (+)-I [or (-)-I], the precipitated (+)-I [or (-)-I] is isolated and, if desired, this crystallization cycle is repeated one or more times.