NL7905551A - NEW INTERMEDIATE PRODUCTION IN THE PREPARATION OF ESTERS OF CYCLOPROPANIC CARBONIC ACIDS AND METHOD FOR PREPARING THE INTERMEDIATE PRODUCT. - Google Patents

Description

«# V.

K 366 NET

Applicant: Shell International Research. Maatschappij B.V.,

Carel van Bylandtlaan 30, 1 s-Gravenhage

Short designation: "New intermediate product for the preparation of esters of cyclopropanecarboxylic acids and process for the preparation of the intermediate product"

The present invention relates to a compound which is a useful intermediate in the preparation of esters of cyclopropanecarboxylic acids. The invention also relates to a process for the preparation of this intermediate.

The esters of cyclopropanecarboxylic acids are compounds with insecticidal activity called "pyrethroids". Since their extremely good insecticidal properties are associated with very low mammalian toxicity, they are of great interest to the agrochemical industry and extensive efforts have been made to economically prepare said esters and their major intermediates.

3A deliberate group of these pyrethroxde compounds can be represented by the general formula: H CE = CX2 / K (I) / 3 1 \ *

CHj - - r - C00R

gh3 H

wherein the asymmetric carbon atoms are each indicated by an *; Each X is a halogen atom; and S is a member of a group of radicals known to confer insecticide molecule activity, for example 3-phenoxybenzyl or alpha-cyano-3-phenoxybenzyl.

It is known that the stereoisomeric form of the acidic component of the ester of formula I for maximum insecticidal activity is 790 55 51 -

a

2 f jfi (1R.cis) form, i.e. the absolute configuration at carbon atom 1 is R and the two hydrogen atoms at carbon atoms 1 and 2 are cis-position. The definition of this nomenclature known as the Elliott nomenclature is contained in an article by M. Elliott, A.W. Farnham, M.F. James, Ρ.Ξ. Meedham and D.A. Pullman, in Mature, 7 197 ^, 2i + 8, 710.

Therefore, if one wishes to prepare these stereoxomeric esters of formula I, either a stereospecific chemical preparation method is required or the desired stereoxomer should be prepared from a racemic form by physical separation techniques.

The latter method is expensive and cumbersome and cannot easily be applied on an industrial scale. The applicant has found a stereospecific method of preparation in which the naturally occurring substance (+) - 3-carene is used as starting material, the formula of which is as follows:

CELL

H 7 ^. | (II) 3 (+) - 3-Carene is an inexpensive, readily available natural terpene and the present application relates to an intermediate which can be used in the preparation of the (1R, cis.) Acid component of the pyrethroid ester of formula I, starting from this terpene.

The present invention relates to a cyclopropane compound of the formula:

H CHO

\ / (III) 0-C0-CH3 CE ^ -yr · - \ - CH2-CH-C0-CH3 es3 s 790 5 5 51

V

V

4 3 £ in the (1R, cis) stereoisomeric form. This compound is called (1R, cis) -1 - (2-formyl-3,3-dimethylcyclopropyl) -3-oxo-2-butyl acetate.

The present invention further relates to a process for preparing (1R, cis) -1- (2-formyl-3,3-dimethylcyclopropyl) -5 3-oxo-2-butyl acetate of formula III, wherein (1R, cis) -1- (2-hydroxy-3-cxobutyl) -3,3-dimethyl-cyclopropane-2-carbaldehyde of the formula:

R CIO

\ / (IV) / \ 0H CH3-p / - \ - CH2-CK-CO-CH3 CH3 h is reacted with an acetylating agent, for example an acetyl halide, such as acetyl chloride or bromide or acetic anhydride.

When an acid halide is used, preferably a hydrogen halide acceptor, for example an organic base, such as an amine, is present; good results have been achieved with pyridine. The present process can be carried out under the conditions described in "Methods of Organic Chemistry" (Louben-Weyl), Book VIII (1952) 516-526, 5-550.

.15 Set of starting material, compound IV, is a new compound t for which protection is claimed in the non-prepublished oc-1 patent application (K 365). A method of preparing compound IV is also described therein; thereby h-acetyl-2-methoxy-7,17-dimethyl-3-oxabicyclo [1,1] heptane is hydrolyzed, preferably using an aqueous acidic medium.

The starting material set can conveniently be prepared from natural (+) - 3-carene and compound IV in the (1R, cis) form is obtained from this material.

The compound and method of the invention are important for a multi-step process for preparing pyrethroid insecticides, for example, esters based on (1R, cis) -2- (2,2-dichlorovinyl) -3,3-dimethylcyclopropanecarboxylic acid, and the corresponding dibromo compound .

790 55 51

a

k s

The invention is further illustrated in the following Example.

EXAMPLE - The preparation of (1R, cis) -1- (2-formyl-3,3-dimethylcyclo-propyl) -3-oxo-2-butyl acetate (Compound III) _

Acetyl chloride (30 mmol.) Was added to a 50 ml flask containing (1R, cis) -1- (2-hydroxy-3-oxobutyl) for 30 minutes at a temperature between 5 and 10 ° C with stirring. ) - 3,3-dimethylcyclopropane-2-carbaldehyde (19sq mmol, 100% (1R, cis), in which both spatial configurations around the C.-0H group were present), pyridine (60mmol.) And dichloromethane (20ml ). The starting material was prepared from (+) - 3-carene. Then the mixture was subsequently stirred for an additional 15 minutes, the temperature was allowed to rise to 20 ° C, water (20 ml) was added, the resulting mixture was acidified with concentrated aqueous hydrochloric acid (sg 1.19) until the pH was 2, then settling the acidified mixture to obtain an aqueous and an organic phase, and after the aqueous phase had separated, the organic phase was washed with two 30 ml portions of a 10 wt% aqueous solution of sodium chloride and a saturated aqueous solution (30 ml) of acid sodium carbonate.

The washed organic liquid was dried over anhydrous magnesium sulfate and the solvent was evaporated from the dried liquid at 1.3 kPa to give a residue (3.3 g) containing compound III (100% (1R, cis ), yield 77%) · The magnetic core spin resonance spectrum of compound III showed the following absorptions (using a solution of compound III in deutero-chloroform and with respect to a tetramethylsilane standard): 25 δ = 1.23 ppm singlet H3C- C-CH3 δ = 1.33 ppm singlet H3C-C-CH3

δ = 2.16 ppm singlet H3C-C (0) -0- δ = 2.19 ppm singlet H3C-C (0) -C

δ = 5.07 ppm double doublets HgC-CH-O- δ = 9.63 ppm doublet 11-0 = 0 multiplets for each ring-bound H atom and for IC-CHg-CH.

790 55 51

Claims (3)

O-C0-CH3-C9-ch-coc-C 3 / C 3 e in the (1R, cis) stereoisomeric form. 2. Process for preparing (IR, cis) -1- (2-formyl-3,3-dimethyl-cyclopropyl) -3-oxo-2-butyl acetate, characterized in that (1R, cis) -1-5 (2-hydroxy-3-oxobutyl) -3,3-dimethylcyclopropane-2-carbaldehyde of the formula: E CEO V OE (IV) 0 ^ - / · -Λς - CE2-CT-CO-CE3 CH3 e in reaction is brought with an acetylating agent. Process according to claim 2, characterized in that the acetylating agent is an acetyl halide. 10 if ·. Process according to claim 2 or 3, characterized in that it is carried out in the presence of a hydrogen halide acceptor. (1R, cis) -1- (2-formyl-3,3-dimethylcyclopropyl) -3-oxo-2-butyl acetate prepared by a method according to any one of claims 2-h. 790 55 51