Process for the preparation of certain pairs of enantiomers of .alpha.-cyano-3-phenoxy-4-fluorobenzyl permethrate

US4782174A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Rainer Fuchs · Halver, DE
• Andreas Wittig · Wuppertal, DE

Key dates

• Filing date: Jun 16, 1986
• Grant date: Nov 1, 1988
• Expiry date: Jun 16, 2006

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C255/53
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for the preparation of a mixture principally comprising the PA1 (b) 1R-3R-.alpha.S+1S-3S-.alpha. and PA1 (d) 1R-3S-.alpha.S+1S-3R-.alpha.R enantiomers of the compound .alpha.-cyano-3-phenoxy-4-fluorobenzyl permethrate, comprising dissolving a mixture of all 8 stereoisomers of the compound .alpha.-cyano-3-phenoxy-4-fluorobenzyl permethrate in an alcohol having 2 to 4 carbon atoms, adding a secondary or tertiary alkyl amine having 2-6 carbon atoms in each alkyl moiety and allowing the mass to crystallize, whereby the desired mixture of enantiomers b) and d) crystallizes out of the solution.