CA1155455A - Intermediates in the preparation of cyclopropanecarboxylate esters and process for their manufacture - Google Patents

Abstract

ABSTRACT

Novel intermediates in the manufacture of pyrethroid insecticides have the following formula:- wherein X is a halogen atom, preferably chlorine or bromine.
The compound preferably has the same stereochemical form as the cyclopropane ring in (+)-3-carene. The novel intermediates can be prepared by a process which comprises oxidising 1-[2-(2,2-dihalovinyl)-3,3-dimethylcyclopropyl]-3-oxo-2-butyl acetate, The starting material is preferably derived from (+)-3-carene,

Description

5~55 K ~67 ~Novel intermediates in the preparation oP
oyclopropanecarboxylate esters and proeess for their manufacture"

The invention r~lates to compounds which are useful intermediates in the preparation of eyclopropanecarboxylate esters. The invention also relates to a process ~or the preparation of these intermediates, The cyelopropanecarboxylate esters are insecticidally-active compounds known as S~pyre~hroids~ and as they combine exceptionally good insecticidal properties with a very low ~alian to.xieity~ they are of considerable interest to the agroehemical industry and mueh effort has been expended in finding economie routes to them and to their principal lnter-mediates, The general formula of one elass of these pyrethroid eompounds ma~ be represented as follows:-H CH=CX2 / 2\

CH3 / \ (I~
C'H3 H
where eaeh asteris~; denotes an asy~metrie carbon atom; each is a halogen atom; and R is a member of a group of radlcals known to impart insecticidal aetivity to ~he molecule, e,g, ~: . :. .. . .
, ~, ~ ~55455

- 2 -

3-pllenoxybenzyl or alpha-oy~no-3 phenoxybenzyl, It is known that the stereoisomeric form of the acid portion o~ the es-ter of formula I should be in the (IR,cis~ ~orm for maximum insecticidal activity, i.e the absolute con~iguration at carbon atom 1 is R and the two hydrogen atoms o~ carbon atoms 1 and 2 are in a cis relationship. This nomenclature is knot~n as the Elliott nomenclature and is de~ined in M, Ell~ott, A W Farnham, N.F James, P H. Needham and D A Pullman, Nature, 1974, 248, 710 It follows, therefore, that if these stereoisomeric esters of formula I are to be prepared, either a stereospecific chemical route is required or the desired stereoisomer must be obtained from a racemic form by physical separation techniques, The latter are expensive and laborious and not readily employed on an industrial scale, The Applicant has found a stereospecific route which uses as starting material the naturally-occurring substance (~-3-carene whose formula is as follows:- ~

H~ h (II) CH3 ~
CH `H
This compound is an inexpensive readily-available natural terpene and the present application relates to intermediates whicll can be used in a route to the (lR,cis)-acid portion of the pyrethroid ester of formula I starting from (~)-3-carene, The present invention provides cyclopropane compounds o~ the general formula:-H ~n=CX
`~/

~ ~-C0{~13 (III~
CH3 CH2-CH-0-CO~I3 _ 3 _ where X is a halogen atom, preferably chlorine or bromine.
These compounds may be named 2-C2-(2,2-dihalovi-nyl)-393-dimethyl-cyclopropy~ ethylidene diacetate `Preferably the compounds of formula III are in the same stereoisomeric form as that of the cyclopropane ring present in naturally-occurring (+~-~-carene, i.e. in the (lR,ci3)-for~, ~
The present invention also provides a process for the preparation of 2-l2-(2,2-dihalovinyl)-3,3-dimethylcyclopropy~
ethylidene diacetate of ~ormula III which comprises oxidising l-l2-(2~2-dihalovinyl)-3~3-dimethylcyclopropyl~-3-oxo-2-but acetate of formula H CH=CX2 ~ (IV) CH3 CH2-CH~C0-CH3 where X is a halogen atom preferabl~ chlorine or bromine.
The oxidation is carried out in the presence of a suitable oxidising agent9 for example an organic peracid such as perbenzoic acid, 3-chloroperben30ic acid, peracetic acid and perphthalic acid, The reaction is conveniently carried out in a suitable solvent, for example chloroform or acetic acid, Alternative oxidation conditions are described in "Methoden der organischen Chemie" (Houben~Weyl) Volume VIII (1952) 559-560 and ~olume VII/
202b (1976) 1984-1988.
The starting material, compound IV, is a novel compound and can oe prepared by a process involving (a) the reaction of a tri(dialkylamino)phosphine or an alkyl ester of an o ~ lo-phosphorous acid bis(dialkylamide) with a tetrahalomethane or a trihalomethane and (b~ the reaction o~ the product resulting from the first step with an aldehyde of the formula;-~ 0-C0~ 3 CH3 CH2-CE~-CO{~3 (V) ~ CH~ H

: , :

~ 1~5~L5

- 4 -both steps belng carried out in the presence o~ a substantiallyinert solvent, The starting material is preferably derived from naturally-oecurring (~)-3-earene as this enables the proeess aeeording to the invention to yield a novel intermediate of ~ormula III in a stereoisomerie ~orm whieh, after eonversion to a pyrethroid inseeticide produees the highest level of pyrethroid insectieide aetivity, Thus the starting material and the product o~ the process according to the invention is preferably in the (lR,cis)-~orm.
The compound and process according to the inventionare o~interest as part o~ a multi-step process to pyrethroid insecticides, e.g esters based on (IR,cis)-2-~2,2-dichlorovinyl)-3,3-dimethyl-cyclopropane carboxylic acid, and the corresponding dibromo analogue, The ~ollowing Example further illustrates the invention, Example - Preparation o~ (lR,cis~-2-E2-(2,2-dichlorovinyl)-3,3-dimethylc~olopropy~ ethylidené diaoetate (Compound III) ~ ne oo~nts o~ a 50 ml ~lask oharged with 1-r2-(2,2~1ichloro-vinyl~-3,3-dimethyloyolopropyl]-3-oxo-2-butyl aoetate (11,9 mmol, 100~ IR,eis, both spatial eonfigurations around C-C(O)CH3) present), ehloroform (10 ml) and 3 chloro-perbenzoic acid ~26 mmol) were stirred m~gnetically for ~ive hours at 20 C, ~hen, another quantity of 3-ehloroperbenæoie aeid (6 mmol) was added and stirring was eontinued for 16 hours, The rea¢tion mixture obtained was mixed w_th dimetl~yl sulphide (2 ml), keeping the ~emperature at 20 C, stirring was continued ~or 15 minutes, dichloromethane (30 ml) was added, the suspended material was ~iltered off, the filtrate was washed with two 20 ml portions of a saturated aqueous solution of sodium hydrogen carbonate and two 20 ml portions of ~0 a lO~ w aqueous solution o~ sodium ehloride The washed organi¢
phase was dried over anhydrous magnesium sulphate and the solvent was evaporated (2 kPa~ from the dried liquid to laave a residue (2.3 g) containing eompound III (lOOC,~ (lR,cis) yield 6~S~) The nuelear ragnetic resonance spectrum o~`compound III showed the 3r~ ~ollowing absorptions (using a solution of eompound III in deuteroehloroform and relative to a tetramethylsilane standard):

.: :

;. , ~
:

1 ~55455 = 1.05 ppm singlet H3C-C-CH3 = 1,15 ppm singlet H3C-C-CH3 = 2.12 ppm singlet both H3C-C(0~-0-= 5.62 ppm doublet HC=CC12 = 6,86 triplet H-C-0-multiplets for each of the H atoms bound to the ring and for HC-CH2CH.

.

,:
..

Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1 A cyclopropane compound of formula (III) (III) wherein X is a halogen atom.

2. A compound according to claim 1 in the same stereoisomeric form as that of the cyclopropane ring present in naturally-occurring (+)-3-carene.

3. A process for the preparation of a compound of formula (III) which comprises oxidising 1-[2-(2,2-dihalovinyl)-3,3-dimethylcyclopropyl]-3-oxo-2-butyl acetate of formula (IV) (IV) (IV)

4. A process according to claim 3 wherein the oxidation is carried out in the presence of an organic peracid.

5. A process according to claim 3 or 4 wherein the starting material of formula (IV) is in the (1R, cis)-form.