C - Chemistry – Metallurgy – 07 – C
Patent
C - Chemistry, Metallurgy
07
C
260/479.8
C07C 255/53 (2006.01)
Patent
CA 1150730
K 1817 ABSTRACT Process for preparing cyclopropane carboxylic acid ester derivatives This invention relates to the preparation of cyclopropane carboxylic acid ester derivatives, which are useful as pesticides. There is provided a process for preparing a mixture of cis- isomers of a compound of formula Image (I) wherein R1 and R2 are independently selected from chlorine, bromine and methyl, consisting predominantly of the lR cis S- and lS cis R- isomers, which process comprises dissolving a mixture of lS cis S- and lR cis R- isomers of the compound of formula I, alone or in the presence of lR cis S- and lS cis R-isomers, in an organic amine base containing from 5 to 7 carbon atoms and being a secondary amine containing two branched alkyl groups or a tertiary amine, crystallising out from a resulting solution of cis- isomers of formula I in the organic amine base a 1:1 mixture of the lR cis S- and lS cis R- isomers, and evaporating off the organic amine base. The process of the invention yields a product which may contain up to twice as much of the most active isomer of the compound of formula I as a racemic mixture of all four cis- isomers, and is a readily effected process which does not involve any sterospecific synthesis or optical resolution steps.
372319
Shell Canada Limited
Smart & Biggar
LandOfFree
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