CS205110B2 - Method of production of esters of 3-substituted 2,2-dimethylcyclopropankarboxyl acids - Google Patents

Description

The present invention relates to a process for the preparation of novel esters of 3-substituted 2,2-dimethylcyclopropanecarboxylic acids. These compounds are useful as starting materials for the preparation of the insecticidally active cyclopropane derivatives described in Czechoslovak Patent Specification No. 205,108.

The compounds according to the invention correspond to the general formula I

O

R ¹ R ¹ C-CH-CH-CH-C- <3.

\ /

C wherein one of R ¹ and R ² is a radical of formula

W - (CF ₂ ) _m -, where

W represents a hydrogen, fluorine or chlorine atom, and m is 1 or 2, the other of which represents a fluorine, chlorine or bromine atom or a radical of formula

Y

X — C—,

From where

X, Y and Z are each independently hydrogen, fluorine or chlorine, and

Q represents an alkoxy group having 1 to 6 carbon atoms.

The process for the preparation of the compounds of formula (I) above consists in cyclizing the compound of formula (II)

W ‘CH3 O

I I II

R ¹ —C — CH2 — CH — C — CH2 — C — Q,

R ² W 'CH 3 (II) wherein

R ^1, R ² and Q have the above meanings, and each of W 'and W "represents a fluorine, chlorine or bromine atom provided that when R ² represents bromine, W' also bromine atom, with a base.

205110 3

Suitable bases for this reaction include tertiary amines such as pyridine, triethylamine, diethylaniline and N-methylplperidine, as well as lower alkali metal alkoxides, i.e., alkoxides containing up to 6 carbon atoms, such as sodium methoxide, sodium ethoxide and sodium tert-butoxide or potassium. The reaction is conveniently carried out in a diluent or solvent of the starting material and the base. This reaction is particularly advantageously carried out by using an alkali metal alkoxide as the base and treating it, for a period of from 0.5 to 20 hours, with a solution of the compound of formula II in an alcohol corresponding to the alkali metal alkoxide used.

At least 2 moles of base are required to convert the compounds of formula II to the compounds of formula I, and this conversion proceeds through two separate steps - cyclization and β-elimination of the hydrogen halide - but it is uncertain in which order these two steps take place or occur simultaneously.

When the above reaction is carried out using only one mole equivalent of base, three different products corresponding to formulas A, B and CR ¹ CH 3 O are obtained.

C = CH — CH — C — CH2 — C — Q,

R2 ⁷ W 'CH3 i (A)

W ‘CH3 O

I I II

R1-C-CH = CH-C-CH2-C-Q,

R ² CH ₃ (B), γ 'of

R-C-CK-CH-CI-I-C- &

> ^{C K} c ch ₃ ch ₃ (C)

Each of these compounds provides a compound of formula (I) by treatment with a further mole equivalent of the base, and the invention therefore includes a process for preparing compounds of formula (I), characterized in that the compound of formula (A), (B) or (C) is treated with at least one base equivalent.

While this procedure can be used to produce all compounds of the formula 1 / is particularly suitable for the preparation of those compounds in which one of Rl and ^R2 is halogen.

Compounds of formula (II) required as starting materials for the preparation of compounds of formula (I) may be obtained by reaction of a compound of formula (III)

O

II

CH2 = CH-C (CH3) 2-CH2-C-Q, (III) in which Q is as defined above, with a compound of formula IV

R ²

R1-C-W,

W '(IV) wherein R 1, R ² , W' and W 'are as defined above, in the presence of a free radical initiator. The free radical initiator in this case may be a physical type initiator, such as irradiation with a suitable radiation source, for example ultraviolet radiation, or a conventional chemical free radical initiator, such as benzoyl peroxide or azobisisobutyronitrile. The reaction may conveniently be carried out using an excess of the compound of formula III as a diluent, at a temperature of 50 ° C to 150 ° C, preferably from 80 ° C to 120 ° C, using a reaction time of 1 to 20 hours, optionally in a closed reaction system. and under autogenetic pressure arising from the reaction.

A particularly suitable compound of formula III is ethyl 3,3-dimethylpent-4-enoate, although other alkyl esters may also be used.

The 3,3-dimethylpent-4-enoic acid ester of the formula III can be replaced by other compounds in which the carboxylate function is replaced by an equivalent function in this context which means a functional group not participating in or preventing the above process but which can additionally be chemically modified by oxidation or hydrolysis to give the corresponding carboxylic acid, such as nitrile, acetyl or formyl.

Alternatively, the compound of formula III may be replaced by a compound of formula IIIa

Q "

CH 6 = CH-C (CH 3) 2-CH-Q ‘, 1 (IIIa) wherein Q‘ represents an alkoxycarbonyl, cyano or acetyl group and Q představuje represents a cyano or alkoxycarbonyl group.

In the process according to the invention, the products of formula (I) usually result as mixtures of different geometric isomers. This can produce a mixture of cis- and trans-isomers, in which one form is often predominant, and in cases where R ¹ is not the same meaning as R ² , E- and Z-isomers of both the cis- and trans-forms may be formed, where again one of the forms prevails.

203110

The above isomeric forms can be separated by physical methods, for example, by fractional crystallization of the corresponding carboxylic acids.

All of the aforementioned isomeric forms are within the scope of the invention.

The invention is illustrated by the following non-limiting examples.

For NMR spectra, the abbreviations have the following meanings:

s = singlet d = doublet t = triplet q = quartet m = multiplet.

Example 1

This example illustrates the preparation of ethyl 3,3-dimethyl-4,6,6-trichloro-7,7,7-trifluoroheptanoate of the formula

CF3CCI2CH2CHCIC _(CH3 J2CH2CO2C2H5.

A mixture of 7.0 g of ethyl 3,3-dimethylpent-4-enoate, 20.0 g of 1,1,1-trichloro-2,2,2-trifluoroethane and 0.1 g of benzoyl peroxide is heated in a sealed glass vial for 5 hours to Mp 100 ° C. The resulting mixture was carefully distilled to give ethyl 3,3-dimethyl-4,6,6-trichloro-7,7,7-trifluoroheptanoate as the fraction boiling at 112-114 ° C / 50 mm Hg, the identity of which was confirmed by IR spectroscopy. and NMR spectroscopy.

Example 2

By analogy to Example 1, the following additional halogenated esters are obtained by reaction of the corresponding haloalkanes with ethyl 3,3-dimethylpent-4-enoate:

(and)

From 1,1-difluorotetrachloroethane, ethyl 3,3-dimethyl-7,7-difluoro-4,6,6,7-tetrachloroheptanoate;

NMR (CDCl3, ppm):

1.10 - 1.35 (m, 9H);

2.10-3.00 (m, 4H),

4.12 (q, 2Ή),

4.52 (double d, 1H).

(ii)

From 1,1,2-trifluorotrichloroethane, ethyl 3,3-dimethyl-6,7,7-trifluoro-4,6,7-trichloroheptanoate, b.p. 75-76 ° C / 6.7 Pa.

(iii)

From 1,1,1-tribromotrifluoroethane, ethyl 3,3-dimethyl-4,6,6-tribromo-7,7,7-trifluoroheptanoate;

NMR (CDCl3, ppm):

1.16-1.44 (m, 9H),

2.50 (q, 2H).

3.04 (q, 2H).

4.18 (q, 2H).

4.60 - 4.74 (m, 1H).

(iv)

From 1,1,1-trichloropentafluoropropane ethyl 3,3-dimethyl-7,7,8,8,8-pentafluoro-4,6,6-trichlorooctanoate;

NMR (carbon tetrachloride, ppm):

1.13-1.40 (m, 9H);

2.14-2.92 (m, 4H);

3.96 - 4.25 (q, 2H);

4.5 - 4.62 (m, 1H).

(in)

From 1,1,1,3-tetrachlorotetrafluoropropane ethyl 3,3-dimethyl-7,7,8,8-tetrafluoro-4,6,6,8-tetrachlorooctanoate.

Example 3

This example illustrates the preparation of ethyl (±) - cis / trans-3- (E / Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl) -2,2-dimethylcyclopropanecarboxylate.

The ethyl 3,3-dimethyl-4,6,6-trichloro-7,7,7-trifluoroheptanoate prepared in Example 1 was dissolved in 30 ml of dry tetrahydrofuran and the solution was added dropwise to a suspension of 2.75 g of tert-butyl ether at 0 ° C. Sodium butoxide (prepared in situ from sodium hydride and tert-butyl alcohol) in 120 ml of dry tetrahydrofuran. After the addition is complete, the mixture is stirred at 0 ° C for 2 hours, acidified with ethanolic hydrogen chloride, diluted with diethyl ether, washed with water, dried anhydrous magnesium sulfate and concentrated by evaporation of the solvent under reduced pressure, and cautious distillation of the yellow oily residue under reduced pressure afforded ethyl (±) - cis / trans-3- (2-chloro-3,3,3-trifluoroprop-1-). en-1-yl) -2,2-dimethylcyclopropanecarboxylate boiling at 70 ° C / 67 Pa. According to NMR spectroscopy, the product is a mixture of about 60% cis-isomer and about 40% trans-isomer (across the cyclopropane ring), wherein in each of these cases it is about 90 a ≥ 95% of the isomers in which the trifluoromethyl group is in the trans position with respect to the cyclopropane ring on the double bond (Z-isomer), and about 5 to 10% of the cis-isomers (E-isomer).

Example 4

The following additional ethyl esters corresponding to formula I are also prepared in an analogous manner to Example 3:

(and)

From ethyl 1-3,3-dimethyl-7,7-difluoro-4,6,6,7-tetrachloroheptanoate ethyl (+) - cis / trans-3- (E / Z-2,3-dichloro-3), 3-difluoroprop-1-en-1-yl] -2,2-dimethylcyclopropanecarboxylate;

NMR (CDCl3, ppm):

1.15-1.55 (m, 9H);

1.55-2.50 (m, 2H);

4.00 - 4.33 (m, 2H),

6.13 and 6.95 (double d, 1H).

(AT)

From ethyl 3,3-dimethyl-6,7,7-trifluoro-4,6,7-trichloroheptanoate ethyl (±) -cis / trans-3- (E / Z-3-chloro-2,3,3) -trifluoroprop-1-en-1-yl) -2,2-dimethylcyclopropanecarboxylate;

NMR (carbon tetrachloride, ppm):

1.20-1.58 (m, 9H);

1.58 - 2.33 (m, 2H),

4.15. (Q, 2H).

5.10-5.41, 5.91 and 6.25 (4d, 1H).

(iii)

From ethyl 3,3-dimethyl-4,6,6, -tribromo-7,7,7-trifluoroheptanoate ethyl (±) - cis / trans -3- (2-bromo-3,3,3-trifluoropropyl) op-1-en-1-yl) -2,2-dimethylcyclopropanecarboxylate.

NMR (carbon tetrachloride, ppm):

1.10 - 1.40 (m, 9H);

1.60 - 2.44 (m, 2H);

3.96 - 4.28 (m, 2H);

5.96-7.26 (m, IH).

(iv)

From ethyl 3,3-dimethyl-7,7,8,8,8-pentafluoro-4,6,6,8-tetrachlorooctanoate ethyl (+ g) / trans-3- (2-chloro-3,3), 4,4,4-pentafluorobut-1-en-1-yl) -2,2-dimethylcyclopropanecarboxylate;

NMR (carbon tetrachloride, ppm):

1.15 - 2.53 (complex signal, 11H),

3.92 - 4.30 (m, 2H),

6.12 and 6.92 (double d, 1H).

(in)

From ethyl 3,3-dimethyl-7,7,8,8-tetrafluoro-4,6,6,8-tetrachlorooctanoate ethyl (± g-cis / trans-3- (2,4-dichloro-3,3) 4,4-tetrichlorobut-1-en-1-yl) -2,2-dimethyl-cyclopropanecarboxylate.

Claims (2)

A process for the preparation of 3-substituted 2,2-dimethylcyclopropanecarboxylic acid esters of general formula I O rWc-CH-CH-CH-C-q, \ / AND. CH, H ₃ C (I) wherein one of R ¹ and R ² is a radical of formula W - (CF ₂ ) _m -, where W represents a hydrogen, fluorine or chlorine atom, and m is 1 or 2, the other of which represents a fluorine, chlorine or bromine atom or a radical of formula Y kde X, Y and Z are each independently hydrogen, fluorine or chlorine, and Q represents an alkoxy group having 1 to 6 carbon atoms, characterized in that the compound of formula (XII) is W ‘CH3 O I I II R1-C-CH2-CH-C-CH2-C-Q, R ² W 'CH 3 (XII) wherein Ri, R ² and Q have the above meanings, and each of W 'and W "represents a fluorine, chlorine or bromine atom provided that when R ² represents bromine, W' also bromine, has at least two molar equivalents base. 2. The process of claim 1, wherein the base is an alkali metal alkoxide containing up to 6 carbon atoms. X — C—, OF