Chemistry of carbon compounds – Miscellaneous organic carbon compounds – C-metal
Patent
1981-04-10
1984-01-24
Love, Ethel G.
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
C-metal
424304, C07C12175
Patent
active
044275986
ABSTRACT:
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 1:1 mixture of 1R cis S- and 1S cis R- isomers substantially free of 1S cis S- and 1R cis R- isomers of a compound of formula: ##STR1## wherein R.sup.1 and R.sup.2 are each independently selected from chlorine, bromine and methyl, which process comprises dissolving a mixture of 1S cis S- and 1R cis R- isomers of the compound of formula I, alone or in the presence of 1R cis S- and 1S cis R-isomers, in organic amine base containing from 5 to 7 carbon atoms and being a secondary amine containing two branched alkyl groups or a tertiary amine, and crystallizing out from the resulting solution of cis - isomers of formula I in the organic amine base a 1:1 mixture of the 1R cis S- and 1S cis R- isomers substantially free of 1S cis S- and 1R cis R- isomers.
The process of the invention yields a product which contains substantially 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 asymmetric synthesis or optical resolution steps.
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M. Elliott et al., "Synthetic Insecticide with a New Order of Activity", Nature, vol. 248, pp. 710-711, Apr. 19, 1974.
Itaya et al., "Synthetic Pyrethroids", A.C.S. Symposium Series 42, pp. 45-54, (1977).
Mason Ronald F.
Wood Derek A.
Love Ethel G.
Shell Internationale Research Maatschappij B. V.
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