FR2557100A1 - PROCESS FOR THE PREPARATION OF 3,5-ETHANO-2,4-DODECADIENOATES - Google Patents

Abstract

THE PRESENT INVENTION RELATES TO A PROCESS FOR PREPARING 3,5-ETHANO-2,4-DODECADIENOATES OF GENERAL FORMULA: (CF DRAWING IN BOPI) CHARACTERIZED IN THAT AN ANION FROM A DERIVATIVE IS REACTED PHOSPHORIC ACID OF GENERAL FORMULA: (CF DRAWING IN BOPI) WITH A BASE IN A DIPOLAR-APROTIC OR PROTIC SOLVENT, WITH A COMPOUND OF GENERAL FORMULA: (CF DRAWING IN BOPI)

Description

The present invention relates to a process for the preparation of

  ethano-2,4-dodecadienoates represented by the following general formula (I):

X, 400 R / I /

  wherein R is a straight or branched chain C 1-4 alkyl group or a C 2-4 alkynyl group, X is a hydrogen atom or a straight or branched chain C 1-4 alkoxy group, Y is a C hydrogen, or

  X and Y together form a double bond.

  The compounds of general formula (I) are useful

to control insects.

  Ethyl (E) -3,5-ethano-7,11-dimethyl-2,4-dodecadienoate, a representative of the compounds of general formula (I), exhibits remarkable activity on various

  insect species [C.A. Henrick, J.N. Labovitz, V.L.

  Graves and G.B. Staal: Bioorg. Chem. 7, 235-250 (1977. Its effectiveness against the mosquito of yellow fever (Aedes aegypti) is three times higher than that of Hydroprene (trade name, Altozar), this compound is 10 times

  more effective on Galleria mellonella, a hundred times more effective

  cace against the yellow flour worm (Tenebrio molitor) and the tobacco budworm (Heliothis virescens) and a thousand times more effective against the housefly (Musca domestica) than the product mentioned above. The other derivatives of general formula (I) are also extremely effective for controlling many species of insects. The isomers (E)

  are much more effective than isomers (Z).

  Two methods have been published for the preparation of

  cadienoates of the general formula (I) (US Pat. Nos. 4,058,666 and 4,000,174). The starting substances of both processes are the 2cyclopentenone derivatives represented by the general formula (II) below: X 0 / I

  o X and Y are as defined above.

  According to the first of the two processes, the 2-cyclopentenones of general formula (II) are reacted with lithium salts derived from alkyl trimethylsilylacetates. According to the other known method, 3- (2,6-dimethylheptyl) -cyclopent-2-en-1-one, a representative of the compounds of general formula (II), is converted with a mixture of lithium diisopropylamide and ethyl acetate, ethyl 7,11-dimethyl-3,5-ethylene-3-hydroxy-4-dodecenoate,

  that is then reacted with prosphoryl chloride.

  In the various processes, a mixture is collected

  1: 1 of the (E) and (Z) isomers, which are subjected to a chroma-

  thin film to obtain the indi-

  vidual. The known methods have a serious disadvantage in that they provide an unfavorable isomer ratio of 1: 1. In addition, these methods are not economically attractive because reagents are expensive (by

  alkyl trimethylsilylacetate, an alkyl

  thium). The present invention aims to provide a synthesis without the above disadvantages, which is economical on an industrial scale. It has been found that the compounds can be obtained

  of general formula (I) with a ratio of isomers favoring

  in the following manner: a) to prepare a subgroup of compounds represented by the general formula (I), where R1 is a straight or branched chain alkyl group and X and Y are as defined above, an anion from an

  phosphoric acid derivative of general formula (III)

after:

O

2 f i

(R 0) 2 P - CH 2 - COOR (III)

  R1 and R3 are each a branched straight chain 1-4 C4 alkyl group, with a base in a dipolar solvent

  aproptic or protic compound with a compound of general formula

  (II) wherein X and Y are as defined above, preferably at a temperature between 20 and 90 ° C; or b) to prepare a subgroup of the compounds of the general formula (I) wherein R 1 represents a C 2-4 alkynyl group and X and Y are as defined above, an ester of the general formula (I), R is a straight chain or branched C 14 alkyl group and X and Y are as defined above, with a base in an alcohol or in the mixture of an alcohol and water, the acid is halogenated;

  carboxylic acid thus obtained, then the halogenated

  thus prepared with C2-4 alkynol.

  It forms in the reaction a mixture of iso-

  containing 70 to 75% of 2 (E) -isomer and 25 to 30% of 2 (Z) -isomer, which is separated into individual isomers by

column chromatography.

  The compounds of general formula (II) used as starting materials in the process described in variant a) are known products or they can be prepared for example according to the Hungarian patent specification N 180 635. The phosphoric acid derivatives of general formula (III) may be derived from trialkyl phosphites

  by an Arbuzow reaction with haloacetic esters.

  /B.A. Arbuzow: Pure Appl. Chem. 9, 307 (1964) 7.

  Anions derived from compounds of general formula

  (III) can be formed with organic bases (eg metal alkoxides, hydrides, amides

  alkali, alkyl or aryllithium or metallic potassium

  than). It is better to use metal alkoxides,

  such as sodium ethoxide or potassium tert-butoxide.

  The reaction is carried out in a dipolar-aprotic solvent

  or protic or a mixture thereof. A dipolar solvent

  aprotic is preferably dimethylformamide, hexamethyl-

  phosphorus triamide or dimethyl sulfoxide. Alkanols are preferably used as protic solvents. The reaction is preferably carried out at a temperature between

 C and 90 C.

  According to variant (b) of the process of the present invention, the alkynyl esters of the general formula (I) are produced. In this connection, the corresponding alkyl esters are reacted with a base in an alcohol or a mixture of alcohol and water. Inorganic bases (eg, hydroxides or carbonates) can be used.

  of alkali metal) as bases. The acid thus obtained is halogenated

  generated by methods known in themselves, and finally the halo

  The resulting genius is treated with C 2 -C 4 alkynol, preferably in an apolar solvent. Benzene, pentane, hexane or cyclohexane are preferably used as

apolar solvent.

  In addition to the foregoing, the invention

  tion still includes other provisions that will emerge $ 7100

of the following description.

  The invention will be better understood by means of

  additional description which follows, which refers to

  examples of implementation of the method object of the present invention. It should be understood, however, that these examples of implementation are given solely for the purpose of

  illustration of the subject of the invention, of which they do not

  in no way constitute a limitation.

Example 1

  Preparation of (E) -3,5-ethanol-7,11-dimethyl

  Isopropyl 2,4-dodecadienoate [I; R1 = (CH3) 2 CH, X = Y = Hf7 0.9 g (0.008 moles of potassium tert.butylate is suspended in 8 ml of anhydrous dimethylformamide and a solution of 1.88 g (0.0008 moles) of diethoxyphosphoryl isopropyl acetate LIII, R1 = (CH3) 2CH, R2 = CH3CH2J7 in 8 ml of anhydrous dimethylformamide is added under

  argon. The reaction mixture is stirred for half a

  hour at room temperature, then added with a solution

  0.83 g (0.004 mole) of 3- (2,6-dimethylheptyl) -2-

  cyclopentenone in 5 ml of anhydrous dimethylformamide and

  The mixture is stirred at 70 ° C. for 6 hours. Dimethylformat

  The residue is distilled off in vacuo, the residue is taken up in 15 ml of ice water and extracted five times with a total of 100 ml of ether; the ethereal phases are combined, washed with water and with a saturated solution of sodium chloride, dried over magnesium sulphate,

  then the solvent is distilled off.

  High-pressure liquid chromatography

  The product thus obtained contains, in a ratio of 72:28, isomers (E) and (Z), which are separated by low pressure column chromatography (Kieselgel G,

  hexane-ethyl acetate 95: 5, 1-1.5 bar).

  Yield in isomer (E): 0.57 g (48.6%).

  Rf = 0.38 (hexane-ethyl acetate 95: 5) HPLC (Column: CH romsil 10 pm, L = 300 mm, d = 4.6 mm, 3P from Pont 830, detection 254 nm, F = 2 cm / min Ap = 300 PSI, eluent: hexane-ethyl acetate 97: 3) tR = 5 min. IR (NaCl): 1710 (CO), 1620 (C = C), 1470, 1385, 1370, 1260,

  1200, 1140, 1105, 1000, 965, 830 cm1.

  1H-NMR (CCl4): δ 0.75 / 9H, d, J = 6Hz, 3CH3, 1.1 / 6H, de, J = 6Hz, 2CH3 /, 1.2-2.95 / 14H, m , 6CH2, 2CH /, 4.71 / 1H, q, J = 6Hz, O-CH /, 5.3

  / 1H, mc, C2 C = CH /, 5.75 / 1H, mc, C4 C = CH /.

  Isomer yield (Z) 0.20 g (17%).

  Ed = 0.46 t = 6.1 min. IR (NaCl): 1705, 1615, 1470, 1390, 1370, 1265, 1200, 1140, -1

1105, 995, 965, 830 cm -1.

  1 H-NMR (CCl 4): δ 0.75 / 9H, d, J = 6Hz, 3CH 3 /, 1.1 / 6H, d, J = 6Hz, 2CH 3 /, 1.22.95 / 14H, m, 6CH 2 , 2CH /, 4.7 / 1H, q, J = 6 Hz, O-CH /, 5.2

  / 1H, mc, C2 C = CH /, 6.9 / 1H, mc, C4 C = CH /.

Example 2

  Preparation of (E) -3,5-ethano-7,11-dimethyl-

  Ethyl 2,4-dodecadienoate (I; R1 = CH3-CH2, X = Y = H)

  A suspension of 2.42 g (0.02 mol) ter.

  potassium butoxide in 15 ml of anhydrous dimethylformamide is treated with a solution of 4.48 g (0.02 mol of diethoxyphosphoryl ethyl acetate (III; R = R2 = CH3-CH2)

  in 10 ml of anhydrous dimethylformamide and the reaction mixture

  tional is stirred under argon for half an hour. A solution of 1.46 g (0.007 mol) of 3- (2,6-dimethylheptyl) -2cyclopentenone (II; X = Y = H) in ml of dimethylformamide is then added to the mixture and stirred at 60 ° C. for 10 hours. . The solvent is distilled off in vacuo, the residue is taken up in 25 ml of ice water, extracted three times with a total of 100 ml of ether, the ethereal phases are combined, washed with water and

  brine, dried over magnesium sulphate, and then

is removed by distillation.

  High pressure liquid chromatography of the residual product indicates that it shows a significant

  : 30 isomers (E) and (Z), which are separated by chroma-

  low pressure columnography (Kieselgel 60, 0.02-0.2;

  hexane-ethyl acetate 95: 5, 1-1.6 bar).

  Isomer yield (E): 0.89 g (45.5%).

  Rf = 0.2 (hexane-ethyl acetate 95: 5) t R = 10.83 min (hexane dichloromethane 98: 2) 1H-NMR (CDCl 3): δ 0.87 / 9H, d, J = 6 Hz, 3CH3 /, 1, 28 / 3H, t, J = 7Hz, CH3 /, 1.1-2.6 / 12H, m, 5CH /, 3.04 / 2H, m, CH /, 4.15 / 2H , q, J = 7 Hz, O-CH 2 /,, 63 / 1H, t, J = 1.5 Hz, C2 C = CH /, 6.0 / 1H,

m, C4 C = CH /.

  S.M .: M 278 (75), 233 (23), 193 (44), 166 (100), 138 (31),

  (21), 91 (38), 77 (14), 71 (23), 57 (41),

43 (64).

  Yield in isomer (Z): 0.34 g (17.3%).

  Rf = 0.3 tR = 16.0 min. 1H-NMR (CDCl3):? SO, 86 / 9H, d, J = 6Hz, 3CH3 /, 1.28 / 3H, t, J = 7Hz, CH3 /, 1.1-2.7 / 14H, m, 6CH2, 2CH /, 4.15 / 2H, q, J = 7Hz, OCH2 /, 5.45 / 1H, m,

C2 C = CH /, 7.12 / 1H, m, C4 C = CH /.

  MS: M 278 (75, 233 (23), 193 (44), 166 (100), 138 (31),

  120 (21), 91 (38), 77 (14), 71 (23), 57 (41),

43 (64).

S7100 Example 3 8

  Preparation of (E) -3,5-ethano-7,11-dimethyl-

  ethyl 11-methoxy-2,4-dodecadienoate (I; R = CH3-CH2,

X = OCH3, Y = H)

  A suspension of 2.24 g (0.02 mol) potassium tert.butylate in 10 ml anhydrous dimethylformamide is

  added with a solution of 4.48 g (0.02 mol) of

  2 xyphosphoryl ethyl acetate (III: R = R = CH 3 -CH 2) in 10 ml of anhydrous dimethylformamide and the suspension thus obtained is stirred under nitrogen for half an hour. A solution of 2.38 g (0.01 mol) of 3- (2,6-dimethyl-6-methoxyheptyl) -2-cyclopentenone (II; X = OCH3, Y = H) in 10 ml is then added to this mixture. of anhydrous dimethylformamide and stirred at C for 8 hours. The solvent is distilled off in vacuo, the residue is taken up in 30 ml of ice water and extracted five times with a total of 100 ml.

  ether; the ethereal phases are combined, washed successively

  with water and brine, dried on sulphate

  magnesium, and the solvent is distilled off.

  High-pressure liquid chromatography

  indicates that the residual product is

  72:28 of the isomers (E) and (Z), which are separated by chroma-

  columnography Kiesegel G, hexane - acetone 7: 3).

  Yield of isomer (E): 1.45 g (46.9%).

  Rf = 0.45 (hexane - acetone 7: 3) tR = 1.4 min. (hexane-ethyl acetate 95: 5) 1H-NMR (CCl 4): δ 0.85 / 3H, d, J = 6Hz, CH 3 /, 1.0 / 6H, s, 2CH 3 /, 1.2 / 3H, t, J = 7Hz, CH3 /, 1.15-2.8 / 13H, m, 6CH2, CH /, 3.0 / 3H, s, OCH3 /, 4.0 / 2H, q, J = 7 Hz, OCH 2 /, 5.5 / 1H, m, C 2 C = CH /,, 9 / 1H, m, C 4 C = CH /. Yield in isomer (Z): 0.54 g (17.4%)

R = 0.5

  f tR = 2.9 min. 1H-NMR (CCl 4): δ 0.8 / 3H, d, J = 6Hz, CH 3 /, 1.1-2.8 / 13H, m, 6CH 2, CH / n 0.95 / 6H, s, 2CH 3 /, 1.25 / 3H, t, J = 7Hz, CH3 /, 2.95 / 3H, s, OCH3 /, 4.0 / 2H, q, J = 7Hz, OCR2 /, 5.4 / 1H , m, C2 C = CH /, 7.05

/ 1H, m, C4 C = CH /.

Example 4

  Preparation of (E) -3,5-ethano-7,11-dimethyl-

  Isopropyl-11-methoxy-2,4-dodecadienoate

-I; R = (CH3) 2-CH, X = OCH3, Y = HJ.

  A suspension of 2.24 g (0.02 mol) of potassium tert.butylate in 15 ml of anhydrous hexamethylphosphorus triamide,

  is added a solution of 4.76 g (0.02 mol) diethoxygen

  isopropyl phosphoryl acetate L-III; R1 = (CH3) 2CH, R = CH3-CH2] in 10 ml anhydrous hexamethylphosphorus triamide and the mixture is stirred at room temperature for half an hour, under argon. Then we add a solution

  2.38 g (0.01 mol) of 3- (2,6-dimethyl-6-methoxyheptyl) -

  -2-cyclopentenone (II; X = OCH3, Y = H) in 10 ml of hexamethyl-

  phosphorus triamide anhydrous and stirred the mixture at 70 ° C. for 8 hours. The solvent is distilled off in vacuo, the residue is taken up in ice water, extracted five times with a total of 100 ml of ether; the ethereal phases are combined, washed with water and with a saturated solution of sodium chloride, dried over sulfate

  of magnesium and the solvent is distilled off.

  High pressure liquid chromatography indicates that the residual product has a ratio

  : 30 isomers (E) and (Z) which are separated by chroma-

  columnography (Kieselgel 60, hexane - acetone 7: 3).

  Yield of isomer (E): 1.4 g (43.3%).

  Rf = 0.37 (hexane-ethyl acetate 91: 9).

  tR = 5 min. (hexane - ethyl acetate 97: 3) IR (NaCl): 1705 (CO), 1615 (C = C), 1470, 1385, 1365, 1260,

1205, 1105, 1080, 995 cm1.

  1H-NMR (CCl4): δ 0.9 / 3H, d, J = 6Hz, CH3 /, 1.1 / 6H, d, J = 6Hz, 2CH3 /, 1.2 / 6H, s, 2CH3 / , 1.2-2.8 / 13H, m, 6XH 2, CH 2, 2.95 / 3H, s, OCH 3, 4.9 / 1H, J = 6Hz, OCH 3, 5.55 / 1H, m , C2 C = CH /, 6.0 / 1H, m, C4 C = CH /. Yield of isomer (Z): 0.62 g (19.2%) Rf = 0.43 tR = 6.1 min. IR (NaCl): 1700 (CO), 1610 (C = C), 1460, 1385, 1365, 1260, -1

1205, 1080, 990 cm.

  1H-NMR (CCl 14): δ 0.95 / 3H, d, J = 6Hz, CH 3 /, 1.1 / 6H, d, J = 6Hz, 2CH 3 /, 1.2 / 6H, s, 2CH 3 / , 1.2-2.8 / 13H, m, 6CH2, CH2, 2.9 / 3H, s, OCH3 /, 4.9 / 1H, q, J = 6Hz, -OCH /, 5.4 / 1H, m, C2 C = CH /, 7.2

/ 1H, m, C4 C = CH /.

Example 5

  Preparation of (E) -3,5-ethano-7,11-dimethyl-11-

  Ethylmethyl-2,4-dodecadienoate (I; R1 = CH2-CH3, X = OCH3, Y = H). A solution of 1.6 g (0.02 mol) of sodium ethoxide in 10 ml of ethanol is added with a solution of 4.48 g (O) 02 mol) of diethoxyphosphoryl acetate (III; R 1 = R 2 = CH 2 -CH 3) in 15 ml of anhydrous ethanol, and the mixture is stirred at room temperature for half an hour under argon. Then we add a solution

  2.38 g (0.01 mol) of 3- (2,6-dimethyl-6-methoxyheptyl) -

  -2-cyclopentenone (II; X = OCH 3, Y = H) in 10 ml of anhydrous ethanol and the reaction mixture is stirred at 70 ° C. for 8 hours. The solvent is distilled off under vacuum, the residue

  is taken up in 25 ml of ice water, extracted three times

  its with a total amount of 90 ml of ether; the extracts are combined, washed successively with water and in brine, dried over magnesium sulphate and the solvent is

2557 1 00

distilled off under vacuum.

  Liquid chromatography indicates that the residual product has a 70:30 ratio of (E) and (Z) isomers. After separation by column chromatography, 1.22 g (39.5%) of isomer (E) and 0.48 g (15.5%) of isomer (Z) are collected. The compounds are identical to those that are

  prepared in accordance with Example 3.

Example 6

  Preparation of (E) -3,5-ethano-7,11-dimethyl-

  Isopropyl-11-methoxy-2,4-dodecadienoate

/ -I; R = (CH3) 2CH, X = OCH3, Y: H_7.

  A suspension of 2.24 g (0.02 mol) potassium tertbutylate in 15 ml of anhydrous dimethylformamide is

  added with a solution of 5.3 g (0.02 mol) of diisopropanol

  isopropyl poxyphosphoryl acetate C-III; R1 = R2 = (CH3) 2CH] in 10 ml of anhydrous dimethylformamide and the mixture is stirred at room temperature for half an hour, under argon. Then a solution of 2.38 g is added

  (0.01 mole) 3- (2,6-dimethyl-6-methoxyheptyl) -2-cyclopen

  Teneone (II; X = OCH 3, Y = H) in 10 ml of anhydrous dimethylformamide and the reaction mixture is stirred at 70 ° C. for 6 hours. The dimethylformamide is distilled under vacuum, the residue is taken up in ice water and extracted with ether, the ethereal extract is washed successively with water and brine, dried over magnesium sulphate and

  solvent is distilled off.

  Liquid chromatography indicates that the residual product has a 75:25 ratio of the (E) and (Z) isomers, which are separated by column chromatography

low pressure.

  Yield in isomer (E): 1.55 g (48.0%) Yield in isomer (Z): 0.53 g (16.4%)

  The compounds are identical to the products prepared according to

example 4.

Example 7

  Preparation of (E) -3,5-ethano-7,11-dimethyl-11-

  propargylmetoxy-2,4-dodecadienoate

(I; R = CHMC-CH 2, X = OCH 3, Y = H)

  1.5 g (0.00465 moles) of (E) -3,5-ethano) isopropyl 7-, 11-dimethyl-11-methoxy-2,4-dodecadienoate; R = (CH 3) 2 CH, X = OXH 3, Y = H 3 is dissolved in the mixture of 1 ml of methanol and 7 ml of 5N sodium hydroxide solution and the reaction mixture is heated in a bath

  water at 90 ° C for 2 hours, with vigorous stirring.

  It is then cooled, the alcohol is distilled off

  under vacuum and the aqueous solution is extracted with ether.

  The aqueous phase is acidified with a 5% sulfuric acid solution while being cooled and then extracted.

  with ether. The ether solution is dried over

  magnesium fate, the solvent is distilled off,

  the residual carboxylic acid is dissolved in 6 ml of

  anhydrous thylformamide, then added 0.6 g (0.005 mol) of thionyl chloride, while being cooled. The reaction mixture is stirred at 35 ° C. for half an hour, cooled

  at room temperature and added with 50 ml of pentane.

  The upper pentane phase is separated, the solution of pentanic acid chloride is added 0.31 g (0.32 ml,

  0.055 moles) of propargyl alcohol while being cooled.

  The mixture is stirred at room temperature for one hour, washed successively with water, 2N sodium hydroxide solution and again with water, dried over water.

  magnesium sulphate and the solvent is distilled off

  lation. Liquid chromatography indicates that the residual product (1.0 g, 67%) is

  : 40 isomers (E) and (Z), which are separated by chroma-

  columnography. Yield of isomer (E): 0.46 g (31%).

  tR = 12 min. (hexane - methylene chloride - ethyl acetate:

83: 16: 1)

  1 H-NMR (CCl 4): δ 0.8 / 3H, d, J = 6Hz, CH 3 /, 1.0 / 6H, s, 2CH 3 /, 1.05-1.5 / 7H, 3CH 2, CH 2, 1.9-2.1 / 6H, m, 3CH2 /, 2.2 / 1H, t, J = 2Hz, C = CH /, 2.98 / 3H, s, OCH3 /, 4.5 / 2H, d, J = 2H Hz, O-CH 2 /, 5.45 / 11m, C 2, C = CH /, 5.9 / 1H, m, C 4 C = CH /.

  MS: M 318 (1), 286 (13), 263 (3), 203 (7), 147 (6),

  91 (18), 73 (100), 55 (23), 41 (21), 39 (11).

  Isomer yield (Z): 0.23 g (15.5%) tF = 14 min. 1H-NMR (CCl 4): δ 0.8 / 3H, d, J = 6Hz, CH 3 /, 1.0 / 6H, s,

  2CH3 /, 1.05-1.5 / 7H, 3CH2, CH2, 1.9-2.1

  / 6H, m, 3CH2 /, 2.25 / 1H, t, J = 2Hz, C = CH /, 3.0 / 3H, s, OCH3 /, 4.55 / 2H, d, J = 7Hz, O-CH 2 /, 5.3 / 1H, m, C 2 C = CH /, 7.0 / 1H, m,

C4 C = CH /.

  As is apparent from the foregoing, the

  This intervention is in no way limited to those of its modes of implementation, of realization and of application which have just been described more explicitly; on the contrary, it embraces all the variants that may come to the mind of the technician in the field, without departing from the framework or

  the scope of the present invention.

Claims (6)

  1. Process for the preparation of 3,5-ethano-2,4-   -dodecadienoates represented by the following general formula (I): wherein R 1 is a straight or branched chain C1 to C4 alkyl group or a C2 to C4 alkynyl group, X is an atom of hydrogen or a straight or branched chain C1-C4 alkoxy group, Y is a hydrogen atom, or X and Y together represent a double bond, characterized in that a) to prepare a subgroup of the compounds represented by the general formula (I), where R 1 is a straight or branched chain alkyl group, and X and Y are as defined above, an anion derived from a phosphoric acid derivative of the general formula (III) below is reacted : o: O 2 i (R2 0) 2 P - CH2 - COOR1 (III)   wherein R 1 and R 2 each represents a straight or branched chain C1-C4 alkyl group, with a base in an aprotic orprotic dipolar solvent, with a compound of the following general formula (II): x Y y wherein X and Y are such as defined above, preferably at a temperature between 20 and 90 C; or b) for preparing a subgroup of compounds represented by the general formula (I), wherein R 1 is a C 2-4 alkynyl group and X and Y are as defined above,   an ester of general formula (I) is reacted, where R   has a straight or branched chain C1 to C4 alkyl group and X and Y are as defined above, with a base in an alcohol or a mixture of an alcohol and water, the carboxylic acid thus obtained is halogenated and react the halide   thus obtained with C2-4 alkynol.   2. Process according to variant (a) of the claim   1, characterized in that an alcoholate is used   metal, preferably sodium ethoxide or potassium butoxide as a base.   3. Process according to variant (a) of the claim   cation 1, characterized in that dimethylformate is used.   mide or hexamethylphosphorus triamide as aproticpolar solvent.   4. Process according to variant (a) of the claim   cation 1, characterized in that an alkanol is used as protic solvent.   5. Process according to variant b) of the claim   cation 1, characterized in that inor-   ganes, preferably an alkali metal hydroxide, as a base.   6. Process according to variant b) of the claim   cation 1, characterized in that the alcohol propargy- as alkynol.