Process for the resolution of enantiomers of benzopyran derivatives

US5103025A · kind A · utility

Assignee

• Merck Patent GmbH · DE

Inventors

• Ralf Devant · Darmstadt, DE
• Rolf Gericke · Seeheim-Jugenheim, DE

Key dates

• Filing date: Nov 2, 1990
• Grant date: Apr 7, 1992
• Expiry date: Nov 2, 2010

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D493/04
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

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.