CS231994B2 - Manufacturing process of 2-cyclopenane derivatives - Google Patents

Abstract

3-Substituted-2-cyclopentenone derivatives of the general formula (I> <IMAGE> wherein R<1> and R<2> represent independently from each other a hydrogen atom or a straight-chained or branched C1-4 alkyl group, R<3> stands for a hydrogen atom or a C1-4 alkoxy group, Y represents hydrogen, or R<3> and Y together represent an oxygen atom or a double bond, are prepared by a) reacting a 2,5-dodecanedione derivative of the general formula (II), <IMAGE> with an alkali or alkaline-earth hydride or a lithium-(di-C1-6 alkyl amide) in an aprotic solvent, and reacting further the compound of the general formula (III) thus obtained, <IMAGE> with an acid; or b) reacting a compound of the general formula (III) with a base. The compound of the general formula (I) are - with the exception of one derivative - new and they serve as intermediates for the preparation of derivatives possessing valuable insect control activity.

Description

(64) A method for producing 2-cyclopentenone derivatives

The invention relates to 2-cyclopentenone derivatives substituted in the 3-position of the general formula I

in which

R ¹ and R ² are each independently hydrogen or C 1 -C 4 straight or branched chain alkyl,

R ³ represents hydrogen or C 1 -C 4 alkyl,

Y is hydrogen or

R ³ and Y together represent an oxygen atom or a double bond.

Compounds of formula I may serve as intermediates in the preparation of derivatives of formula IV

in which

R ¹ , R ² , R ³ and Y are as defined above, and

R is a straight or branched chain alkyl group.

The compound of formula IV is useful for controlling insects.

One of the compounds of formula I (the one in which R ¹ , R ² , R ³ and Y are hydrogen atoms) is known. Other derivatives of formula I have not been described. According to the invention, even a known derivative is produced in a novel manner.

The only known derivative of formula (I) has been used to produce a compound of formula (IV) wherein R ¹ , R ² , R ³ and Y are hydrogen and R ⁴ is an ethyl group of the compound [CA Henrick et al., Bioorg. Chem. 7, 235 (1978)]. The authors have found that the compound thus produced is highly effective in controlling many insect species. Its efficacy is two times on Aedes aegypti, ten times on Galleria mellonella, tenebrio molltor and on Heliothis virescens one hundred times, and on Musea domestica (housefly) a thousand times higher than that of Hydroprene.

Two methods for the production of cyclopentenone derivatives used as intermediates are known [Bioorg. Chem. 7, 235 (19713)]. In the first method, 2,6-dimethyl-1-heptane is used as the starting compound, which gives the corresponding trialkylborane by treatment with diborane. The trialkylborane is treated first with bromine, then with sodium methoxide. Of the thus prepared L-bromo-2,6-dilnet hylheptanu ^L 'by the action of metal, magnesium in ether afforded Grlgnardovo agent which is reacted with 3-methoxy-cyclopent-2-en-l-that had been prepared from 1.3 -cyclopentadiol and diazomethane. Finally, from 3- (2,6-dimethyl-heptyl] cyclopent-2-en-l-one by acid cleaved to yield water cyklopenttnonového · derivative of formula I (wherein R 1, R ^2, R ³ and Y hydrogen atoms) in low yield (13%).

This process is uneconomical because expensive starting compounds and expensive reactants (diborane, diazomethane) are used, and also because very low yields are achieved. In addition, the process is unsuitable for the preparation of compounds of formula I which contain an alkoxy group (R ³ in formula II is O-alkyl) because compounds with such a group are acid-sensitive. as is well known.

According to the improved method of A. A. Henrick and Sipol. is used as the · parent compound

2,6-dimethyl-1-heptene. This compound is hydroborated to 1-hydroxy-2,6-dimethyl-heptane, which is converted to 1-chloro-2,6-diethyl-heptane by the action of thionyl chloride. Treatment of the lithium metal with the chloro compound yields the corresponding alkyllithium derivative, which is reacted with 2-cyclopentenonene (prepared by bromination of cyclolethanoan followed by cleavage of hydrogen bromide). 1-Hydroxy-1- (2,6-dimethyl-heptyl) -2-cyclolynthine is obtained which, by oxidation with chromic acid (chromium trioxide and sulfuric acid) in ether solution, provides a cyclopentenone derivative of the formula I in which R1, R ^2, R ³ and Y are hydrogen. Although · yield according to this process is higher than the previous method, this method has several disadvantages. Besides the fact that it requires expensive · starting material and expensive reactant, it is not · synthesis suitable for · The preparation of derivatives which contain alkoxy groups (i.e. compounds of formula I in which R 'represents an alkoxy group), since strongly acidic agents are used in two reaction stages. The object of the invention is a simple and economical synthesis of compounds of formula I · production of the known compound (R 1, R ² and R · ³ · represent hydrogen and R ⁴ represents an ethyl group) as well as new compounds o formula IV with valuable biological properties.

SUMMARY OF THE INVENTION The present invention is characterized in that the novel 2,5-d-decanedlonone derivative of the general formula II is used

wherein R 1, R 2, R ³ and Y are as defined above, reacted with an alkali metal or caustic earth metal hydride or lithium [dialkyl (C 1 -C 6) amide] in an aprotic solvent, preferably an ether solvent Of the type, and the compound of formula III thus produced

wherein R 1, R 2, R ³ and Y are as described above, without further isolation, with acid, or the compound of formula III after isolation is treated with a base and finally the compound of formula I thus obtained is separated from the reaction mixtures.

When an alkali metal or caustic earth metal hydride is used, the reaction is carried out at a temperature in the range of -20 to 80 ° C, preferably at 0 to 30 ° C. When using lithium [dialkyl (C 1 -C 6 carboamide)], the reaction is carried out at lower temperatures, preferably between 0 ° C to -80 ° C, particularly preferably in the range of -30 ° C to -70 ° C. using a metal hydride or lithium [dialkyl (C 1 -C 6) amide], then the reaction is preferably carried out under an inert gas.

Preferably, ether-type solvents (such as γ-γ-1-γ-γ, dioxane, β-hydrofuran, etc.) are used as the alroic solvent.

Preferably, sodium or potassium hydride is used as the alkali metal hydride. Lithium [dialkyl (1-6C) carbons] is preferably lithium diethylamide or lithium diisopropylamide.

Intermediate. of Formula III need not be isolated. It can be converted into the desired compound of formula I by treatment with a catalytic amount of acid ^1, which is present in the reaction mixture.

The reaction of the intermediate of formula III with a base is preferably carried out in an organic solvent. The alkali or caustic earth metal hydroxides or hydrides are preferably used as bases.

According to our research, the compounds of formula II, serving as starting compounds for ^; the process described in variant a, is prepared from the citricellal derivative of the general formula V

wherein R ¹ , R ² , R ³ and Y are as defined above, which may be prepared from commercially available citronellal by known methods. In the preparation of the compounds of formula II, the compound of formula V is reacted with a methyl vinyl ketone of formula VI

O

CH2-CH-C-CH3 (VI) in the presence of a catalytic amount of the thiazolium salt of general. of formula VII

in which

R ⁵ represents a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, a 2-hydroxyethyl group or a benzyl group,

R ⁶ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,

R ⁷ represents a C 1 -C 4 alkyl group, straight or branched chain, or a 2-hydroxyethyl group, and

X 'is a halide ion.

The reaction is optionally carried out in an organic solvent - preferably anhydrous dioxane - at a temperature which is not too high, preferably at a temperature in the range of from 65 to 65 ° C. 80 ° C. With respect to the amount of catalyst, at least one equivalent of a base is used - preferably trialkylamine. The product is isolated from the reaction mixture by extraction or distillation in vacuo.

The term &quot; alkyl &quot; as used in this specification and in the specification refers to straight or branched chain alkyl groups (e.g., methyl, ethyl, proipyl, isopropyl, butyl, etc.). 4 carbon atoms "means straight or branched chain alkoxy groups having 1 to 4 carbon atoms (eg, methoxy, ethoxy, propoxy, isobutoxy, etc.). The term" halide ion "may mean a chloride, bromide or iodide ion, with preferably a chloride ion.

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

Example 1

Preparation of 7,11-dimethyl-11-methoxy-2,5-cyclododecanedione (compound of formula II wherein R 1, R 2 and Y are hydrogen and R 3 is methoxy)

A mixture of 37.3 g (0.2 mole) of 7-methoxy-6,7-dihydrocitronellal (a compound of formula V wherein R 1, R ² and Y are hydrogen and R 3 is methoxy), 21 grams (0.3 mole) ) distilled. methyl vinyl ketone. (compound of formula VI) and 5 g (0.02 mol). 3-benzyl-5- (2'-hydroxyethyl) -4-methylthiazolium chloride (a compound of formula VII wherein R 5 is benzyl, R 6 is methyl, R 7 is -CH 2 -CH 2 -OH and X is chlorine ) is heated to 70 ° C. 3.64 g (5 ml, 0.036 mol) of anhydrous triethylamine was added and the reaction mixture was quenched. The mixture was stirred at 75 ° C for 16 hours under argon. Then, it is cooled, poured into. mixtures. 150. milliliters of aqueous. sulfuric acid solution o ^; weight concentration 5%. and 15 g of ice and extracted twice with a total of 300 ml of dichloromethane. The extract is washed successively with 20 ml of water, 20 ml of 5% sulfuric acid solution, 20 ml of water, dried over magnesium sulphate and the solvent is distilled off. The residue is distilled under reduced pressure. pressure (26.7 Pa). Yield 23 g. (44.9.%). Mp 110-114 ° C (26.7 Pa).

For C 15 H 28 O 3 (256.37) calculated :. % C, 70.26;% H, 11.15; 69.98% C, 11.00% H.

IR spectrum. (NaCl ·):

1715, 1460, 1400, 1380, 1360, 1150,

1070 cm @ -1.

¹ H-NMR spectrum (CDCl 3):?

0.9 (3H, doublet, J = 6Hz, CM),

1.1 (6H, singlet, 2),

1.3 (6H, compound multiplet, ЗСН2),

2.1 (3H, singlet)

2.58 (4H, s, 2CH 2),

3.08 (3H, singlet, OD).

Mass Spectrum: M ⁺ 256 (2%); m / z 241 (10); 226 (15); 225 (20); 210 (10); 186 (25); 131 (8); 99 (90); (100), 43 (95).

Example 2

Preparation of 3- (2,6-dimethyl-6-methoxyheptyl) -3-hyidroxy-cyclopentanone (the compound of formula III wherein R ^1, R ² and Y are hydrogen atoms and R ³ represents a methoxy group), and

3- (2,6-dimethyl-6-methoxy-heptyl) -2-cyclopentenone (a compound of formula I wherein R ¹ , R ² and Y are hydrogen and R ³ is methoxy)

To a suspension of 0.5 g (0.0176 min) of sodium hydride (an oil suspension containing 80 percent by weight sodium hydride) in 20 ml of anhydrous ether, a solution of 2.56 g (0.01 mol) of 7,11- of dimethyl-11-methoxy-2,5-dodecanedione (a compound of formula II wherein R ¹ , R ² and Y are hydrogen and R ³ is methoxy) in 10 mL of dry ether during V2 hours under argon with stirring. The mixture was then stirred at room temperature for 6 hours. Finally, it is poured into ice water, the organic phase is separated, the aqueous phase is extracted with 20 ml of ether, the organic phase is combined, washed with water and dried over magnesium sulphate. The solvent was distilled off. The residual oily residue is purified by chromatography on Kieselgel G, eluting with a 10: 0.2 mixture of benzene and methanol.

3- (2,6-dimethyl-6-methoxyheptyl) -3-hydroxycyclopentanone: yield 0.80 g (31.3%). R _f = 0.25 (benzene-methanol 10: 1).

IR spectrum (NaCl):

3410, 1720, 1460, 1380, 1350, 1230, 1140, 1060 cm ^{@ -1} .

¹ H-NMR spectrum (CDCl 3):

0.9 (3H, doublet, J = 6Hz, CM),

1.05 (6H, singlet, 2 cm),

1.3 (6H, .multiplet, ЗСН2),

2.1 (4H, multiplet, 2 CH2);

2.55 (2H, multiplet, CH 2), 3.05 (3H, singlet, ОСНз),

3.55 (1H, multiplet, exchangeable for deuterium, OH).

Mass Spectrum: M ⁺ 256 (1%); m / z 238 (2); 207 (37); 206 (2); 188 (11); 183 (3); 150 (2); 135 (3); 123 (4); 109 (5); 108 (4); 96 (3); 93 (5); 91 (7); 85 (8); 81 (5); 73 (100).

3- (2,6-dimethyl-6-methoxyheptyl) -2-cyclopentenone: yield: 0.45 g (18.9%). Rf = 0.47 (benzene-methanol 10: 1).

For C15H26O2 (238.36) calculated: 75.58% C, 11.00% H, found: 75.07% C, 10.72 ° / o H.

IR spectrum (NaCl):

1705, 1615, 1460, 1430, 1400, 1380, 1360, 1270, 1240, 1160, 1070 cm ^-1 .

¹ H-NMR spectrum (CCl 3):

0.9 (3H, doublet, J = 6Hz, CM),

1.05 (6H, singlet, 2 cm),

1.3 (6H, multiplet, 3 CH2)

2.3 (6H, multiplet, 2)

3.03 (3H, singlet, OMN),

5.75 (1H, multiplet, = CH).

Mass Spectrum: M ⁺ 238 (1%); m / z 223 (1); 207 (3); 165 (4); 151 (2); 135 (2); 124 (3); 123 (7); (3); 108 (2); 96 (8); 95 (7); 93 (4); 85 (11); 81 (8); 73 (100).

As a by-product, 0.24 g (10.08%) of 2- (1,5-dimethyl-5-methoxyhexyl) -3-methyl-2-cyclopentenone was obtained. R _f = 0.64 (benzene-methanol 10: 1).

For C ₁₅ N ₂ O ₂ (238.36) calculated: 75.58% C, 11.0% H, found: 75.42% C, 11.21% H.

IR spectrum (NaCl):

1690, 1630, 1460, 1380, 1360, 1200 and 1070 ^cm-first

¹ H-NMR spectrum (CDCl ₃ ):

1.05 (6H, singlet, 2 cm),

1.1 to 1.7 (10H, m, 3 CH _2, CH ₃ CH), (3H, s, _CH3);

2.4 (4H, m, 2 CH ₂₎

3.02 (3H, s, _OCH3).

Mass Spectrum: M ⁺ 238 (2%), m / z 223 (1), 206 (5), 151 (10), 150 (7), 135 (7), 124 (6), 109 (3), 123 (6), 109 (3), 95 (4), 93 (4), 91 (3), 85 (2), 81 (6), 73 (100),

Example 3

Preparation of 3- (2,6-dimethyl-6-methoxyheptyl) -2-cyclopentenone (formula I wherein R ^1, R ² and Y are hydrogen and R ³ represents a methoxy group)

To a stirred suspension of 2 g (0.36 mol) of sodium hydride (80% oil suspension) in 30 ml of dry ether was added dropwise a solution of 5.12 g (0.02 mol) of 7,11-dimethyl-11-methoxy-2,5-dodo. .kandionu (compound of formula II wherein R ^1, R ² and Y are hydrogen atoms and R ³ represents a group rnethoxyiovou) in 200 ml of anhydrous ether over half an hour under nitrogen. The suspension was stirred at room temperature for 12 hours. The reaction mixture was then poured into a mixture of 20 ml of 5% aqueous hydrochloric acid and 30 g of ice. The organic phase is separated, the aqueous phase is extracted with 30 ml of ether. The organic extracts were combined, washed with water, dried over magnesium sulfate and the solvent was distilled off.

The remaining product is dissolved in a mixture of 25 ml of ethanol and 50 ml of 0.5 N sodium hydride. The mixture was refluxed for 2 hours. The reaction mixture was cooled to room temperature, extracted twice with a total of 100 mL of ether; the ether extract is washed with 20 ml of saturated sodium chloride solution and dried over magnesium sulfate. The solvent was distilled off. The residual oil was purified by Kieselgel 69 column chromatography, eluting with 10: 0.2 benzene / methanol. Yield: 2.16 g (45.38%) of a compound identical to the product prepared according to Example 2.

Example 1 a d 4

Preparation of 3- (2,6-dimethyl-6-methoxyheptyl) -2-cyclopentenone (formula I wherein R ^j, R ² and Y are hydrogen atoms and R ³ represents a methoxy group)

К stirred solution of 1.3 g (0.013 mole] of dry diisopropylamine and 10 ml hexamethylíosfortriamldu in 30 ml of tetrahydrofuran maintained at -65 ^Q C is added a solution containing 0.9 g (0.014 mole) of butyllithium in hexane The mixture was stirred at -30 ° C for half an hour, then cooled to -65 ° C and a solution of 2.56 g (0.01 mol) of 7,11-methoxy- was added dropwise over two hours. 2,5-dodecanedione (compound of formula II wherein R ^1, R ² and Y are hydrogen and R ³ represents a methoxy group] in 30 ml of anhydrous tetrahydro-uranium. the mixture was stirred one hour at -65 ° C. Then Allow to warm to room temperature and stir for an additional 3 hours.

The reaction mixture was poured into water and extracted twice with a total of 106 mL of ether. The ether extract was washed with water and saturated sodium chloride solution, dried over magnesium sulfate and the solvent was distilled off. The residue is purified by chromatography on a Kieselgel 60 column, eluting with a 10: 0.2 mixture of benzene and methanol. Yield 1.0 g (42%) of the compound identical to the product produced according to Example 2.

Example 5

Preparation of 3- (2,6-dimethyl-6-methoxyheptyl) -2-cyklopentenon.u (compound of formula I wherein R ^1, R ² and Y represents a hydrogen atom and R ³ represents a methoxy group)

1.2 g (0.0047 mol) of 3- (2,6-dimethyl-6-methoxyheptyl) -3-hydroxy-cyclopentenone (compound of formula III) are dissolved in a mixture of 25 ml of ethanol and 25 ml of 0.5 N sodium hydroxide. wherein R ¹ , R ² and Y are hydrogen and R ³ is mothoxy). The mixture was boiled for two hours. It is then cooled to room temperature and extracted twice with a total of 100 ml of ether. The ether extracts were combined, washed with water and saturated sodium chloride solution and dried over magnesium sulfate. The solvent was distilled off. The residue is purified by chromatography on a Kiesegel 40 column, eluting with 10: 0.05 benzene / methanol. Yield 0.7 g (63%) of the compound identical to the product prepared according to Example 2.

Example 6

Preparation of 7,11-Dimethyl-2,5-dodecaidione (compounds of formula II wherein R ¹ , R ² , R ³ and Y are hydrogen)

К solution of 19.5 g (0.125 mol) dihydrocitronellalu (compound of formula V wherein R ^1, R ^2, R ³ and Y = H) 14 g (0.2 Imola, 16 ml) of freshly distilled methyl vinyl - ketone (compound VI) - and 2.0 g (0.01 mol) of 3-ethyl-5- (2-hydroxyethyl) -4-methylthiazolium chloride (a compound of formula VII wherein R ⁵ is ethyl, R @ ⁶ is methoxy, R @ ⁷ is --NH2 --CH2 --OH and X @ - is chlorine anion, and 1.82 g (0.018 mol, 2.5 ml) of triethylamine is added in 50 ml of anhydrous dioxane. The mixture was maintained for 24 hours. The water bath temperature of 80 DEG C. ^and then cooled, the separated "precipitate is filtered off and the solvent was distilled off. The residue is distilled off under reduced pressure (133 Pa). Yield: 11 g [48.7%]. Bp. 103 to 105 43 / 26.7 mm Hg, 128-130 ° C / / 133 Pa, n D ²⁵ - 1442.

For C ₁₄ H ₂₆ O ₂ (226.35) calculated: 74.28% C, 11.58% H, found: 73.96% C, 11.32% H.

IR spectrum (NaCl):

1715, 1460, 1380, 1360, 1140, 1080 ^cm-first

1 H-NMR spectrum (OCl ₄ ):

0.9 (9H, doublet, J = 6 Hz, 3 CH _3),

1.2 [6H, m, 3 CH ₂₎

2.1 (3H, s, _CH3);

2.2 (2H, m, _CH2),

2.58 [4H, s, _CH2).

Mass spectrum: M ⁺ 226 (5%), m / z

114 (100); 113 (29); 99 (46); 71 (90); 56 (36).

Example 7

Preparation of 3- (2,6-dime.thylheptyl) -3-hydroxycyklopentanonu (compound of formula III wherein R ^1, R ^2, R ³ and Y are hydrogen atoms) and 3- (2,6-dimethylheptyl) -2 -cyklopentenonu (compound of formula I wherein R ^1, R ^2, R ³ and Y = H)

To a stirred suspension of 1.0 g (0.33 mol) sodium hydride (oil suspension containing 80% by weight sodium hydride) in 40 ml anhydrous ether, a solution of 3.0 g (0.013 mol) 7,11- dimethyl-2,5-dodecanedione (compound of formula II wherein R ^1, R ^2, R ³ and Y = h) in 10 ml of anhydrous ether over a half hours under argon. The reaction mixture was stirred for an additional 10 hours at room temperature. It is then poured into a mixture of 20 ml of 5% aqueous hydrochloric acid and 40 g of ice and extracted twice with a total of 200 ml of ether. The extracts were combined, washed with water and saturated sodium chloride solution and dried. The solvent is distilled off. The residue is purified by column chromatography on Kieselgel G, eluting with a 10: 0.05 mixture of benzene and methanol.

3- (2,6) Dimethylheptyl) -3-hydroxycyclopentanone: Yield: 0.72 g (24.5%). R _f = 0.28 (in a mixture of benzene-methanol 10: 0.1).

IR spectrum [NaCl]:

3410, 1720, 1460, 1380, 1360, 1220 ¹ .

1 H-NMR spectrum (CDCl 3):

0.9 (9H, doublet and doublet)

J = 6 Hz, ZNN3),

1.28 (6H multiplet, 3 CH2)

2.3 (8H, m, 4 _CH2);

3.35 (1H, multiplet, exchangeable deuterium, OH).

3- (2,6-Dimethylheptyl) -2-cyclopentenone: Yield: 1.1 g (40.62%). R _f = 0.62 (benzene-methanol 10: 0.2).

For C ₁₄ H ₂₄ O (208.33) calculated: 80.70% C, 11.61% H, found: 80.49% C, 1.1.42% H.

IR spectrum (NaCl):

1705, 1615, 1460, 1380, 1360, 1250, 1150, 1090 ^cm-first

1 H-NMR spectrum (CDCl ₃ ):

0.9 (9H, doublet and doublet)

J = 6 Hz, 3 CH ₂ )

1.3 (6H, multiplet, 3 CH ₂ )

2.4 (6H, m, 3 CH ₂₎

5.95 (1H, multiplet, - = CH).

2- (1,5-Dimethylhexyl) -3-methyl-2-cyclopontenone (by-product): yield: 0.29 g (10.74%). Rf = 0.83 (10: 0.2 benzene / methanol).

For C ₁₄ H ₂₄ O (208.33) calculated: 80.70% C, 11.61% H, found: 80.64% C, 11.74% H.

IR spectrum (NaCl):

1690, 1630, 1460, 1400, 1380, 1360, 1320, 1290 and 1260 cm ^-1 .

¹ H-NMR spectrum (CDCl 3):

0.9 (6H, doublet, J = 6 Hz, 2 CH ₃ ), up to 1.8 (10H, multiplet, 3 CH 2, CH, N 2), (3H, singlet, CH ₃ ),

2.35 (5H, m, 2 CH _2, CH).

Example 8

Preparation of 3- (2,6 dimethyl 1) -2-cyclopentenone (formula I wherein R ^1, R ^2, R ³ and Y = H)

To a solution of 1.3 g (0.013 mol) of anhydrous diisopropylamine and 5 ml of hexamethylphosphoric triamide in 20 ml of anhydrous tetrahydrofuran was added, under vigorous stirring at -65 ° C under argon, a 15% solution of butyllithium in hexane (containing 0.9 g ( 0.014 mol) of butyllithium). The mixture was stirred for an additional 20 minutes at -30 ° C. It is then cooled to -65 ° C and a solution of 2,26 g (0,01 mol) of 7,11-dimethyl-2,5-dodecanedione (a compound of formula II in which R ¹ , R ² , R ³ and Y = H) in 20 mL of anhydrous tetrahydrofuran over 2 hours. The mixture was stirred at -65 ° C for one hour. It was then allowed to warm to room temperature and stirring was continued for an additional 6 hours. The mixture was poured into water and extracted twice with ether for a total of 100 ml. The ether extracts were washed with water, saturated solution. sodium chloride, dried over magnesium sulfate and the solvent was distilled off. The residue is purified by chromatography on a Kieselgel 60 column, eluting with a 10: 0.05 mixture of benzene and methanol. Yield: 0.91 g (43.75%) of product identical to the compound prepared according to example 2.

Example 9

Preparation 7, ll-dimethyl-10-dodeoe.n-2,5-cn'.i (compound of formula II wherein R · ^L and R2 are hydrogen and R ³ together with Y represent a double bond)

To a solution of 15.4 g (0.1 mole) of citronellal (a compound of formula V wherein R 1 and R 2 are hydrogen and R 3 and Y together are a double bond), 14 grams (0.2 mole, 16 mL) freshly of distilled methyl-vinyl-ketone (compound IV) and 3.1 g (0.01 mol) of 3-ethoxyethyl-5- (2,1-hydroxyethyl) -4-methyl-1-thiazolium bromide formula VII wherein R ⁵ represents' C2H5OCH2CH2- group and R ⁸ is methyl) in 40 mL · anhydrous dioxane was added 1.82 g (0.018 mole) of anhydrous triethylamine ·. The mixture was stirred in an oil bath at 80 ° C under argon for 24 hours. It is then cooled, the precipitated compound is filtered off and the solvent is distilled off. The residue is distilled under vacuum. Yield: 10.5 g (46.8%). T. v .: 105 to 107 degrees Celsius (26.7 Pa); n ₀ 25 · = 1.470.

IC spectrum (NaCl):

1715, 1460, 1380 and 1360 cm ¹ .

NMR Spectrum. (CCU):

0.9 (3H doublet, J = 6Hz, CH3),

1.2 (12H, multiplet, 3 CH2 and 2 CH3),

2.1 (3H, singlet, CH 3),

2.58 (4H, singlet, 2 CH2),

5.1 (1H, multiplet, .dbd.CH).

Mass Spectrum: M + 224 (10%), m / z 206 (19), 166 (66), 153 (13), 141 (42), 114 (16), 110 (49), 99 (100), 71 (44), 69 (71), 55 (39), 43 (90), 41 (71).

Example 10

Preparation of 3- (2,6-dl · methyl-15-heptenyl) -2l Cyclopentone (cyclopentyl) compound (compounds of formula I wherein R 1 and R ² are hydrogen and R 3 together with Y are together a double bond)

To a vigorously stirred mixture of 2.6 g (0.026 mol) of anhydrous diisopropylamine, 10 ml of hexamethylphosphoric triamide and 40 ml of anhydrous tetrahydrofuran at -65 ° C under argon is added a solution of butyllithium in hexane containing 1.8 g (0.028 mol) of butyllithium. (ie containing butyllithium by weight. · concentration · 15%) · · The mixture is stirred at -30 ° C for half an hour. It is then cooled to a temperature below -60 DEG C. and a solution of 4,5,1 g (0,02 mol) of 7,11-dimethyl-10-dodecene-2,5-diene is added over two hours. (a compound of formula II wherein R 1 and R ² 'are hydrogen atoms and R 3 at the bottom with Y are a double bond) in 30 mL of anhydrous tetrahydrofuran. The reaction mixture was stirred at -65 ° C for one hour. It was then allowed to warm to room temperature and stirred for an additional 8 hours.

The reaction mixture was then poured into water, extracted twice with ether in a total amount of 100 ml, the extracts were combined, washed with water and saturated sodium chloride solution and dried over magnesium sulfate. The solvent was distilled off and the residue was purified by Kieselgel 60 column chromatography, eluting with a 10: 0.05 mixture of benzene and methanol. Yield: 1.4 g (34%). R _F = 0.7 (benzene: methanol = 10: 0.3).

IR spectrum (NaCl):

1705, 1615, 1460, 1380, 1250, 1150 and 1090 cm ⁴ .

1H-NMR Spectrum:

0.9 (3Ή, d, J = 6Hz, CH 3),

1.2 (12H, multiplet, 3 CH 2 and 2 CH 3),

2.3 (6Ή, multiplet, 3 'CH 2),

5.1 (1H, multiplet, · CH).

Example 11

Preparation 7 lldiimethyl LL-2,5-ethxxy Dodel kandionu (compound of formula II wherein R 1, R ² and Y are hydrogen and R3 is OCH2CH3)

A mixture of 20 g (0.1 mole) of 7-Ethoxy-6,7-dihydrocitranellalu (compound community ·. · Of formula V wherein R 1, R ² and Y are hydrogen and R3 is ethoxy), 10.5 g (0 (15 mole) of distilled methyl vinyl ketone (compound VI) and 2.5 g (0.01 mole) of 3-benzyl-5- (2-hydroxyethyl) -4-methylthiazolium chloride (compound of formula VII), wherein R ⁵ 'is benzyl, R ⁶ is methyl, R ⁷ is -CH 2 CH ² OH and X is chlorine) is heated to 70 ° C. 1.8 g were added. Anhydrous triethylamine (2.5 mL, 0.018 mol) was added and the reaction mixture was stirred under nitrogen in a 75 ° C oil bath for 16 hours. It is then cooled to room temperature, poured into a mixture of 100 ml of a 2.5% aqueous sulfuric acid solution and 25 g of ice and extracted twice with dichloromethane for a total of 150 ml. The extract is washed with water,

With a 5% aqueous sulfuric acid solution, again with water, - dried over magnesium sulphate and the solvent is distilled off. The residual oil was distilled under vacuum. Yield: 11.6 g (42.96 percent). M.P .: 112-114 ° C / 26.7 Pa.

For C 16 H 30 O 3 (270.40) calculated: 71.07% C, 11.18% H, found: 70.86% C, 10.80 ·% H.

IC spectrum (NaCl):

1715, 1460, 1380, 1300, 1150, 1070 cm @ -1.

1H-NMR Spectrum (CCl4):

0.9 (3H, doublet, J = 6 Hz, CH 3),

1.3 (15H, multiplet, 3 CH2 and 2 CH3),

2.1 (3H, singlet, CH3),

2.55 (4H, s, 2 CH 2),

3.6 (2H, quartet, J = 6Hz, OCH2).

Example 12

Preparation of 3- (2,6-dimethyl-6-ethoxy.heptyl) -2-cyclopentenone (a compound of formula I wherein R 1, R 2 and Y are hydrogen-and R 3 are ethoxy)

To a mixture of 2.6 g (0.026 mol) of anhydrous -diisopropylamine and 10 ml of hexamethylphosphoric triamide in 50 ml of anhydrous tetrahydrofuran, which was cooled to -65 ° C, was added a solution containing butyllithium (15 wt. %) in hexane (1.8 g, i.e. 0.028 mol of butyllithium). The reaction mixture was stirred at less than -30 ° C for half an hour. It is then cooled to -65 degrees Celsius. In two hours, a solution of 5.4 g (0.02 mol) of 7,11-dimethyl-l-ethoxy-2,5-dodecanedione (0becného- compound of formula II wherein R 1, R ² and Y are hydrogen atoms and R 3 is ethoxy) in 20 mL of anhydrous tetrahydrofuran. The mixture was stirred for an additional 8 hours at room temperature when stirred for one hour at -65 ° C. The reaction mixture was poured into water and extracted twice with a total of 100 mL of ether. The extracts are combined, washed with water and saturated sodium chloride solution. After drying over magnesium sulfate, the solvent was distilled off. The residue is purified by chromatography on a Kieselgel 60 column, eluting with a 10: 0.1 mixture of benzene and methanol. Yield: 1.9 g (37.7 percent). Rf = 0.53 (in benzene-methanol 10: 1).

For C 16 H 23 O 2 (252.38) calculated: 76.14% C, 11.18% H, found: 75.91% C, 10.89% -H.

IR spectrum (NaCl):

1705, 1615, 1460, 1380, 1270, 1240, 1155 and 1065 cm ^1st

1 H-NMR spectrum (CDCl 4):

0.9 (3H, doublet, J = 6 Hz, CH 3),

1.05 (6H, singlet, 2 CH 3),

1.3 (9H, multiplet, 3 CH 2, CH 3),

2.3 (6H, -multiplet, 3 CH2)

3.6 (2H, quartet, J = 6Hz, OCH2),

5.78 (1H, multiplet, --CH).

Claims (6)

OBJECT OF THE INVENTION A process for the preparation of 2-cyclopentene derivatives substituted in the 3-position of the general formula I Y {/} in which R 1 and R ² are each independently hydrogen or C 1 -C 4 alkyl, straight or branched chain, R3 represents a hydrogen atom or an alkoxy group having from 1 to 4 carbon atoms, Y means. - hydrogen atom, or R ³ and Y together represent an oxygen atom or a double bond, characterized in that to the 2,5-dodecanedione derivative of general formula wherein R 1, R ² , R 3 and Y are as defined above, are treated with an alkali metal hydride , metal or caustic -zeminy lithiumfdlálkyl (1 -to-C6 alkyl) amide] in -aprotlckém solvent the solvent and preferably in an ether type and the so produced -compound of formula III wherein R1, ^R2, R3 and Y as described above, without further isolation, the acid is further treated with a compound of formula III, or after treatment with a base, and optionally the compound of formula I thus obtained is separated from the reaction mixture. 2. A process according to claim 1, wherein the compound of formula (II) is reacted with an alkali metal hydride, preferably sodium hydride. 3. A method according to claim 1, characterized in that it is lithium. dialkyl of 1 to 6 carbon-amides] uses lithium diethylamide or lithium diisopropylamide. 4. The process according to claim 1, wherein the base is an alkali metal or caustic earth metal hydroxide, preferably sodium hydroxide. 5. The process according to claim 1, wherein the reaction with the metal hydride is carried out in an aprotic solvent, preferably ether. 6. The process of claim 1 wherein the reaction with lithium! di-C1-6 alkyl (1-6C) is carried out in a mixture of tetrahydrofuran with hexamethylphosphoric triamide.