LACTONES

LACTONES

English Abstract

ABSTRACT
"Lactones"
Esters of 3-.beta.,.beta.-dihalovinyl-2,2-dimethylcyclopropane-
1-carboxylic acids are prepared from 4-.beta.,.beta.-dihalovinyl-3,
3-dimethyl butyrolactone by reaction with an inorganic
acid halide to open the lactone ring with formation of the
corresponding 4-haloacid halide, which with alcohols affords
the corresponding 4-haloacid ester which is cyclised by
bases to give the above product. The products are
intermediate for insecticidal esters and the process
offers fewer stages and higher yields than the processes
hitherto described or used.

Claims

- 5 -
The embodiments of the invention in which
an exclusive property or privilege is claimed are
defined as follows:
1. A process for the preparation of cyclopropane
carboxylic acid esters of the formula:
<IMG>
wherein R1 is a lower alkyl group, R is a hydrogen atom or
a cyano, carboxy, methyl, ethyl, isopropyl, n-propyl,
tert-butyl, n-butyl, carboxymethyl or cyanomethyl group
and each Y is a chlorine or bromine atom, which comprises
treating a lactone of the formula:
<IMG>
wherein R and Y have the previously defined meanings,
with an inorganic acid chloride or bromide and treating
the product with an alcohol of the formula R1OH and a base.
2. A process for the preparation of a 4-haloacid halide
of the formula:
Y2C=CH.CH Hal.C(CH3)2CHR.COHal
wherein R and Y have the meanings stated in Claim 1 and
Hal represents a chlorine or bromine atom, which comprises
treating a lactone of the formula:

- 6 -
<IMG>
with an inorganic acid chloride or bromide.
3. A process as claimed in Claim 2 wherein R is
a hydrogen atom or a methyl, ethyl, isopropyl, n-propyl,
tert-butyl, n-butyl, carboxymethyl or cyanomethyl group.
4. A process for the preparation of a haloacid
ester having the formula:
Y2C = CH.CH Hal.C(CH3)2.CHR.CO2R1
wherein R1, R and Y have the meanings stated in Claim 1 and
Hal represents a chlorine or bromine atom which comprises
carrying out in succession the process of Claim 2 and
treating the 4-haloacid halide having the formula defined in
Claim 2 with an alcohol of the formula R1OH.
5. The process of reacting
V
<IMG>
with R'OH, to produce the compound II of formula:
<IMG>
wherein Hal is chlorine or bromine

- 7 -
R1 is loweralkyl.
6. The process of reacting
<IMG>
VI
with C2H5OH to produce the compound IV of formula:
<IMG>

Description

~ ~ Dx', 28041/A
This invention relates to a process for the
preparation of cyclopropane carboxylic acid esters,
According to the present invention there is
provided a process by which esters of the formula:
~ = CH Cl3
y/ \CEI--cl ~ CH3
~ R
CO2Rl
wherein R1 is a lower alkyl group, R is a hydrogen atom or
a cyano,carboxy, methyl, ethyl, isopropyl, n-propyl, tert-
butyl, n-butyl, carboxymethyl or cyanoms~hyl group and each
Y is a chlorine or bromine atom, are prepared by treating
a lactone o~ formula
~H3
\ C=CH - CH- ~ - -CH3
~ o/IR
wherein R and Y have the previously de~ined meanings,
with an acid chloride or bromide and treating the product
with an alcohol of the formula RlOH and a base.

This process proceeds in three stages which may
be carried out. if desired, especially in respect o-E the
first and second stages, withou~ isolation of the inter-
mediate products, Each .individual stage, and the two
combinations of successive stages, are also features of
the inven-tion,
In the first stage of the process the lactone
ring is opened and the appropriate 3,3-dimethyl-4-chloro
(or bromo)- 6,$-dichloro (or dibromo) hex-5-enoyl chloride
(or bromide) is obtained, In this stage it is preferred
that R be a hydrogen atom or a methyl, ethyl, isopropyl,
n-propyl, tert-butyl, n-bu-tyl, carboxymethyl or cyano-
methyl group~
The first stage of the process is conveniently
carried out using at least a molar amount, and preferably
not more than 1,5 molar amounts, of acid chloride or
bromide at a temperature between ambient and the boiling
point of the reaction mixture,
As acid chloridesor bromides there may be
mentioned especially inorganic acid chlorides such as
thionyl chloride, phosphorous pentachloride and phosphorus
oxychloride, which provide hexenjoyl` chloride having a 4-
chloro substituent, and inorganic acid bromides such as
thionyl bromide and phosphorus pentabromide, which provide
acid bromides having a 4~bromo substituent,
The second stage of the process, treatment with
the alcohol of the formula RlOH, is preferably carried
out without isolation of the product of the first stage.
The alcohol is preferably used in excess, for example
1,5 molar proportions, and a reaction temperature from
ambient to the boiling point of the reaction mixture may
--2--

conveniently be used. The alcohol RlOH is preferably
methanol or ethanol.
The product of the second stage, the ester of
the acid of which the acid chlo.ride resulted from the
first stage, may if desired be isolated by conventional
means, for example removal of excess alcohol, RlOH, and
distilla-tion under reduced pressure, but it is not usually
necessary to carry out such isolation before carrying out
the third stage,
The third stage, treatment with the base, may be
carried out at a temperature between ambient and the
boiling point of the reaction mixture using a solvent
conveniently the alcohol, RlOH, The base is preferably
an alkali metal alkoxide, for example NaORl, but may be
another alkoxida or sodium hydroxide in ethanol,
~ he amount of base is preferably from 2.0 to 3,0
molar equivalents,
The cyclopropanecarboxylic ester may be isolated
by conventional means, for example neutralisation by the
addition of e.g, dilute sulphuric acid, separation from
the residue of any salt, removal of excess alcohol by
distillation, addition to water and extraction with a water-
immiscible so].vent, After removal of the solvent the product
may be purified by distillation under reduced pressure.
The cyclopropanecarboxylic ester may be converted
into an insecticidal ester by known means, for example an
ester .interchange reaction with e,g, m-phenoxybenzyl
alcohol using a catalyst uuch as potassium tert,-
butoxide or may be converted into for example the corres-
ponding acid or acid chloride which may then be esterifiedwith e,g, m-phenoxybenzyl alcohol,
--3--

The process of the inventiOn affords a route
to insecticidal esters of 3~ dichloro~or dibromo)
vinyl-2,2-dimethylcycloproparle-~-~arboxylic acids which
has fewer stages and gives higher yields than the routes
hitherto described or used.
The invention is illustxated but not limited by
the following examples in which all parts and percentages
are by weight unless stated otherwise.
ExamPle ,1
29.08 Parts of thionyl chloride were added
dropwise with stirring at room temparature to 20.8 parts
of 2~ dichlorovinyl)-3,3-dimethyl~5-oxotetrahydrofuran,
The mixture was boiled or 1 hour after which the unreacted
thionyl chloride was distilled o~f to give crude 3,3-
dimethyl-4,6,6-trichlorohex 5-enoyl chloride
20 Parts of ethanol were then added dropwise, the
temperature being maintained at below 30C and the mixture
was then refluxed for 1 hour. The product was dis-tilled
under reduced pressure giving 15.28 parts of ethyl 4,6,6
trichloro-3,3-dimethylhex-5-enoate, which contained a minor
amount of unchanged lactone
Example 2
A slurry of 11.2 parts of potassium t-butoxide
in 200 parts of toluene wa~ added 510wly to 13.7 parts of
ethyl 4,6,6 trichloro-3,3-dimethyl-hex-5-enoate stirred at
below 0C and stirred at below 0C for a further 1 hour.
The mixture was neutralised to pH 6 with concentxated
hydrochloric acid Water was added to dissolve the
precipitated salt and the toluene layer separated. The
water layer was extracted again with toluene and the
toluene then removed from the combined extracts giving in
nearly theoretical yield the mixed cis and trans forms of
ethyl 3~ dichlorovinyl-2,2-dimethylcyclopropanecarboxylate.
_a,..