JPS6320214B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing α-hydroxycarbonyl compounds.

The α-hydroxycarbonyl compound produced by the method of the present invention has the following general formula: (In the formula, R represents a methyl or ethyl group,
R′ represents a hydrogen atom or a methyl or ethyl group, and X represents an oxygen atom or a group >CH ₂ , >CH—CH ₃
or >CHC ₂ H ₅ ).

The method provided by the present invention for the preparation of α-hydroxycarbonyl compounds of the general formula [wherein R, R' and X have the above meanings,
R'' represents a hydrogen atom, or if X represents an atom other than oxygen, it can also be a group -COOR (however, R represents a hydrogen atom or a C _1-6 -alkyl group). Cyanohydrin decomposes and groups that may be present - COOR
It consists of cleaving and leaving.

Cyanohydrin decomposition can be carried out thermally, but can also be acid- or base-catalyzed.

In thermal cyanohydrin decomposition, a compound of the formula is heated to a temperature of about 50°C to 400°C, especially about 80°C.
It is convenient to heat it to 250°C.

In acid-catalyzed cyanohydrin decomposition, a compound of the formula is treated with an acid, which is conveniently used in catalytic amounts (e.g. 1/1000-1/10 equivalents) or in larger amounts (e.g. , 1 mole)
Also used. It is only absolutely necessary that the PH of the reaction mixture be below 7.

There are no particular restrictions on the type of acid. Examples of acids that can be used are inorganic acids (e.g. sulfuric acid, hydrochloric acid and sulfurous acid);
organic acids (e.g. formic acid, acetic acid, citric acid and oxalic acid) or acid ion-exchangers (e.g.
Amberlite IRC50, etc.).

In base-catalyzed cyanohydrin decomposition, a compound of the formula is treated with a base, which base is conveniently used in catalytic amounts (e.g. 1/1000-1/10 equivalents) or in larger amounts (e.g. 1/10 equivalents). mole) is also used. It is only absolutely necessary that the PH of the reaction mixture be above 7.

There are no particular restrictions on the type of base. Examples of bases that can be used are inorganic bases, such as alkali metal hydroxides (e.g. sodium hydroxide), alkaline earth metal hydroxides (e.g. calcium hydroxide and magnesium hydroxide), alkali metal carbonates (e.g.
sodium carbonate and potassium carbonate), alkali metal bicarbonates (e.g., sodium bicarbonate), ammonia, other basic salts (e.g., sodium phosphate, potassium hydrogen phosphate, and borax), basic buffer systems ( organic bases such as amines (e.g. triethylamine, pyridine, morpholine, etc.);
Salts of organic acids and strong bases (eg, sodium acetate, formate, oxalate, citrate and lactate), or basic ion exchangers (eg, Amberlite IRA400, DOWEX 2, etc.).

Cyanohydrin decomposition can be carried out in the gas phase or in the liquid phase. The presence of a solvent is not necessary, but is convenient.

Cyanohydrin decomposition is advantageously carried out at temperatures between 50° and 200°C, preferably at about 100°C.

There are no particular restrictions on the type of solvent. Polar solvents, such as water, ammonia or alcohols, or non-polar solvents, such as toluene, benzene, toluene, ether, petroleum ether, etc., can be used.

Particularly suitable systems for carrying out cyanohydrin decomposition are basic ion exchangers in the OH form/water, organic acids or their salts (e.g. acetic acid/water, sodium oxalate/water) or pyridine/toluene at the temperature is approximately 100℃.

When R'' represents a group -COOR (wherein R represents hydrogen or a C _1-6 -alkyl group), in principle first a compound of the following formula or formula is obtained after decomposition of the cyanohydrin.

can also be expressed in the enol form (X=〓
CH, 〓C-CH ₃ or 〓C-C ₂ H ₅ ).

This group - COOR, for example, is initially an ester group -
COOR is hydrolyzed with an aqueous acid or base solution and then the (resulting) carboxylic acid or its salt (R=
H, alkali metals or alkaline earth metal equivalents) can be easily cleaved by decarboxylation, which can be achieved, for example, by heat treatment (50°
200℃).

However, the cleavage of the group -COOR also takes place under the conditions mentioned above for cyanohydrin decomposition, especially if cyanohydrin decomposition is carried out under aggressive conditions.

The term "severe conditions" specifically refers to the following conditions: Acid treatment: PH<3, especially <2 Base treatment: PH > 10, especially > 12 It is used to mean.

The compound of formula is new.

The compound with the formula is the general formula It is advantageously produced by oxidizing a compound of the formula (R, R', R'' and X have the meanings given above).

Particularly suitable oxidizing agents are alkali metal caroates (eg KHSO ₅ ). Preferred oxidizing agents are "Caroat" (trademark) (KHSO ₄ and K ₂ SO ₄
and KHSO ₅ ).

Caroates are conveniently used in amounts of 1-2.5 equivalents, especially 1.1-1.5 equivalents.

The oxidation is preferably carried out in a polar solvent, such as water, alcohol, acetone, or acetonitrile, or a mixture of such solvents.

Conveniently, the pH of the medium in which the oxidation is carried out is about 3-11, and such pH is oxidized by carbonate, phosphate, citrate, borate, etc. in a known manner.
It can be created by a suitable buffer system of the NH ₃ /NH ₄ or oxalate type.

Oxidation is for example -10℃ to 60℃, preferably 0
It can be carried out at temperatures between 10°C and 20°C.

Compounds of the formula (R'' represents the group -COOR) are particularly suitable starting materials in the process of the invention, especially since they are easy to prepare.

The compounds of the formula (X is not an oxygen atom and R'' is a hydrogen atom) are new.

New compounds of the formula represented by formula ′ below can be prepared in particular from dinitriles of the formula
Merck Index, Encyclopedia of Chemicals
and Drugs, 9th edition, 1976, ONR87, Merck & Co., Ltd.
Rahway, New Jersey) or the Dieckmann cyclization (The Merck
Index, see above, ONR23) gives the following schematic formula (wherein R and R' have the meanings given above):
It can be prepared as shown in: Further methods for the preparation of compounds of formula ' include known methods for introducing cyano groups into the corresponding cyclopentanone derivatives, such as halogenation (eg bromination) followed by CN substitution [etc. Oh. House (HOHouse), Modern
Synthetic Reactions, Benjamin Publisher, Menlo Park (1972), pp. 459ff; Organikum,
Organischchemisches Grundpraktikum, VEB
deutscher Verlag der Wissenschaften 4th edition,
1964, 283] or the action of halogenated cyanogens on the corresponding cyclopentanone or its enamine derivative [M. M.Kuhne, J.
Amer.Chem.Soc. 81 , 5400, 1969] as shown in the following schematic formula (wherein R and R' have the meanings given above): α-hydroxycarbonyl compounds of the formula are generally known. These are flavoring substances and/or sugar breakdown products.

The invention is illustrated by the following examples.

Example 1 3,4-dimethylcyclopent-2-ene-2
-Production of All-on (a) 67.1g (1 mol) of crotonitrile and 76g (0.65 mol) of ammonium perchlorate are placed in a reaction vessel, and about 260g of anhydrous ammonia is added to -
Process the mixture while cooling to 70°C. A 15 volt DC voltage (4-5 amps) is applied at -75°C for 15 hours with a mercury anode placed at the bottom of the vessel and a suspended graphite cathode. Evaporate the ammonia. Take the dark brown solution in 700ml of ether and add 250ml of
Wash with ml of water. From concentrated ether solution
31 g (46%) of 3,4-dimethyladiponitrile are obtained (fractional distillation at 107 DEG -109 DEG C./0.15 Torr).

(b) 5.6 g of potassium tert.butyrate in toluene
Reflux for 60 minutes with 6.8 g of 3,4-dimethyladiponitrile in 50 ml. Wash the cooled solution with 50 ml of water and concentrate. 6.4 g (94%) of 2-cyano-3,4-dimethyl-cyclopent-1-enylamine having a melting point of 92°-100° C. are obtained. IR (CHCl ₃ ) 3500 and 3400 (NH),
2180 (CN), 1638 and 1596 (C=C); MS: 136 (M ⁺ ), 121 (100%), 94.

(c) 2g of the product obtained according to paragraph (b) in 2N
Stir for 10 minutes with _50ml of _H2SO4 , then 30ml each time
Extract three times with ether to ml. The dried and concentrated ether phase contains 1.8 g (89%) of 2-cyano-3,4- with a boiling point of 75°-76°C/0.05 Torr.
Contains dimethylcyclopentanone.

IR: 2250 (CN), 1750 (strong, C=O); MS: 137 (M ⁺ , 100%), 122, 108, 94, 69,
68.

(d) 2 g of the product obtained according to paragraph (c) are dissolved in 20 ml of water with 1.4 g of borax and 1.17 g of sodium hydroxide and the solution is treated with 6.4 g of Caroat (Degutsa). After 30 minutes, the mixture is filtered, acidified to PH1 with sulfuric acid and extracted four times with 30 ml portions of methylene chloride each time. After concentration, 1.57
g (71%) of 2-cyano-2-hydroxy-
An enantiomeric mixture of 3,4-dimethylcyclopentanone is obtained. ^n20D ₌ 1.5490.

IR: 3150 (OH), 2250 (very weak, CN), 1710
(C=O); MS: 139 (M ⁺ ), 121, 112, 95, 83 (100%).

(e) 1 g of the product obtained according to paragraph (e) in 15 ml of water.
The mixture is refluxed for 6 hours with 0.8 g of sodium acetate in a saline solution and then extracted four times with ethyl acetate. Concentration of ethyl acetate yielded 0.578 g (70%) of 3,4-dimethyl-cyclopent-2-en-2-ol-1
- Brown crystals with a melting point of 69°-71°C (from water)
obtained in the form of

NMR (CDCl ₃ ): δ=5.8ppm single line, broad/1 proton (OH); 2.8-2.5 multiplet/
2 protons (H-5); 2.2-1.8 multiplet/
1 proton (H-4); 1.98 singlet/3 protons (CH ₃ , C-3); 1.18 doublet (J
=7Hz)/3 protons (CH ₃ , C-4).

The same product was obtained from 2-cyano-2-hydroxy-3,4-dimethylcyclopentanone as described in paragraph (d) by refluxing 2 g of the latter in 60 ml of saturated sodium bicarbonate solution for 4 hours. can be prepared by extracting the cooled solution four times with 30 ml of methylene chloride each time. 0.98 g (60%) of pure (GC and TLC) crystalline product with a melting point of 66 DEG -68 DEG C. is obtained from the concentrated organic phase. Recrystallization is carried out from water.

Example 2 3-hydroxy-4,5-dimethyl-2 (5H)
-Production of furanone (a) 10g of 2-cyano-3-methyl-valero-γ
-Lactone [prepared as described in Chem.Abstr. 58 , 5508b (1962)] was dissolved in 150 ml of water.
With 14g of borax in ml, 24.5g of kalot,
Process while simultaneously adding dropwise 65 ml of 2N sodium hydroxide. After 30 minutes, add 100ml of ethyl acetate to the mixture.
Wash with water, acidify to pH1 with 80ml of 2N sulfuric acid,
Extract four times with 100 ml of ethyl acetate. 6.7 g (60%) of 2-cyano from the dried and concentrated extract
2-Hydroxy-3-methyl-valero-γ-lactone (epimer mixture) is obtained in the form of a yellow oil. ^n20D ₌ 1.4509.

IR: 3370 (OH); 2250 (weak, CN); 1782 (C=
O); MS: 155 (2%, M ⁺ ), 128 (M-HCN), 133,
96,83 (100%).

(b) Reflux 3.5 g of the above lactone with 2.75 g of sodium acetate in 150 ml of water for 3 hours. The cooled solution is extracted four times with 50 ml of acetic acid each time, the extracts are dried over sodium sulfate and concentrated. 1.43 g (50%) of gas chromatographically pure 3-hydroxy-4,5-dimethyl-2(5H)-furanone are obtained.

NMR (CDCl ₃ ): δ=7.2ppm single line, wide/
1 proton (OH); 4.91 quartet x quartet (J ₁ = 6.5Hz, J ₂ = 1.5Hz) / 1 proton (H
-5); 1.95 doublet (J = 1.5Hz) / 3 protons (CH ₃ , C-4); 1.44 doublet (j =
6.5Hz)/3 protons (CH ₃ , C-5); MS: 128 (M ⁺ ), 113, 85, 83 (100%), 72,
57, 55.

Example 3 Preparation of 3-methylcyclopent-2-en-2-olone (a) Sodium ethylate in 400 ml of ethanol
30.6 g of the solution is treated with 80 g of diethylphosphono-acetonitrile. After 2 hours, 71.5 g of levulinic acid ethyl ester are added dropwise at 5° C. (60 minutes required) and the cloudy solution is then refluxed for 30 minutes.
After that, about 300ml of ethanol was distilled off, and 400ml of
Add 1N hydrochloric acid. The organic phase is separated, the aqueous phase is extracted three times with 200 ml of ether each time, and the combined organic phases are concentrated. 5-cyano-4-methyl-
50.5g (67%) of a cis-trans mixture of 4-pentenoic acid ethyl ester has a boiling point of 85° to 86°C/0.05
It is obtained in the form of a clear yellow liquid.

(b) hydrogenating 25 g of the above ester in the presence of 1 g of palladium/activated carbon in 150 ml of methanol for 2 hours;
The mixture is then filtered and the liquid concentrated. boiling point
24.9 g (99%) of 2-methyl-adipomononitrile monoethyl ester at 76° to 81°C/0.04 torr
is obtained.

IR: 2250 (CN), 1730 (C=O); MS: 169 (M ⁺ ), 154, 142, 129, 124 (M ⁺ -
OE _t , 100%), 101, 96, 88.

(c) 3.3 g of the ester obtained according to paragraph (b) in 50 ml of toluene and 3.3 g of potassium tert. Reflux with butyrate for 30 minutes. The mixture is then treated with 50 ml of 1N hydrochloric acid, the aqueous phase is separated off and extracted three times with 40 ml each time of methylene chloride. The combined organic phases are dried over sodium sulfate, concentrated and distilled under high vacuum to give 2.22 g of 2-cyano-3-methyl-cyclopentanone (92
%) is obtained.

IR: 2250 (CN); 1760 (C=O); MS: 123 (M ⁺ , 100%), 108, 94, 80, 68,
55.

(d) 1.45 g of the nitrile obtained according to paragraph (c),
Together with 2.3 g of borax and 0.96 g of sodium hydroxide, it is added to 150 ml of water and the mixture is treated at 15° C. with 5.4 g of Caloto (Degutusa) dissolved in 18 ml of water. After stirring for 45 minutes, the mixture is washed with 25 ml of ethyl acetate, acidified with 50 ml of 4N sulfuric acid and extracted three times with 25 ml of ethyl acetate each time. The ethyl acetate phase is dried over sodium sulfate and concentrated to yield 1.35 g (82%) of 2-cyano-2-hydroxy-3-methylcyclopentanone in the form of a brown oil. ^n20D ₌ 1.4708,
Boiling point 120-130℃/0.04 torr.

IR: 3380 (OH), 2250 (weak, C=N), 1760 and 1712 (C=O); MS: 153 (M ⁺ ), 135, 126, 83, 69.

(e) Cyanohydrin 1.5 obtained according to paragraph (d)
25 ml of water with 1.35 g of sodium acetate for 5 hours. The cooled solution is extracted six times with 25 ml of ethyl acetate each time. The organic phases were combined, dried over sodium sulfate, and concentrated to give 554 mg
(yield 45%) of 3-methylcyclopent-2-
En-2-olone is obtained in the form of a yellow powder with a melting point of 92° to 101°C.

Example 4 3,5-dimethylcyclopent-2-ene-2
- Preparation of All-On (a) 2-cyano-3-methyl-cyclopentanone [prepared as described in Example 3(c)] 2.9 g (23.5
mmol) in 60 ml of dry tetrahydrofuran and 2.8 ml of hexamethylphosphortriamide, and this solution was dissolved in 0.62 g of sodium hydride.
(25.9 mmol). 25.9 mmol of a 1.6 molar hexane solution of butyllithium and then 3.67 g (25.9 mmol) of methyl iodide are added at -8 DEG C. under an argon atmosphere. The mixture is kept at about 0° C. for a further 20 minutes (exothermic reaction) and then poured into 75 ml of 1N hydrochloric acid and 100 g of ice. water phase each time
Extract three times with 50 ml of ether, dry over sodium sulfate and concentrate. The resulting oil was subjected to fractional chromatography on 140 g of silica gel using 2 parts of hexane and 1 part of ether. 2-
1.03 g (32%) of a diastereomeric mixture of cyano-3,5-dimethylcyclopentanone are obtained in the form of a yellow oil.

IR: 2250 (CN), 1755 (C=O); NMR (CDCl ₃ ): δ = 1.6-3.5ppm complex multiplet/5 protons (H-2, H-3, H-
4, H-5); 1.29 and 1.14 in each case one single line/6 protons (J=6Hz, CH ₂ -
3 and CH ₃ -5); MS: 137 (M ⁺ ), 122, 108, 94, 81, 68 (100
%).

(b) Dissolve 24 g (175 mmol) of the above cyano compound in 300 ml of water together with 33.3 g (87.5 mmol) of borax and 14 g (350 mmol) of sodium hydroxide, and while cooling the solution, dissolve 87 g (257 mmol) of cyano compound in 266 ml of water. Process with. After stirring for an additional 30 minutes, the pH of the solution is 5.6. The solution is acidified to PH1 with 2N sulfuric acid and extracted three times with 150 ml of ethyl acetate each time. The organic phase is dried over sodium sulfate and concentrated to yield 26.2 g (98%) of 2-cyano-2-hydroxy-3,5-dimethylcyclopentanone in the form of a colorless viscous oil. This oil can be distilled at 50°-60°C/0.035 Torr. n ²⁰ _D =
1.4577.

IR: 3450 (strong, OH), 2250 (weak, CN), 1760
(strong, C=O); NMR (CDCl ₃ ): δ = 4.4 ppm, single line, broad / 1 proton (OH); 3.1-1.6 multiplet /
4 protons (H-3, H-4, H-5);
1.5-1.0 multiplet/6 protons ( _CH3-3 and _CH3-5 ); MS: 153 (M ⁺ ), 135, 126, 120, 109, 96, 83
(100%), 74.

(c) 23.2 g (152 mmol) of the above cyanohydrin
is refluxed with 18.6 g (227 mmol) of sodium acetate in 380 ml of water for 40 minutes under a brisk stream of nitrogen. The cooled solution is extracted three times with 150 ml of methylene chloride each time, and the combined extracts are dried over sodium sulfate and concentrated. 12.0 g of 3,5-dimethylcyclopent-2-en-2-olone, melting point 92°-95°C (from ether/hexane)
(63%).

IR ( _CHCl3 ): 3530 and 3350 (OH), 1710 and 1660
(Strong, C=O); MS: 126 (M ⁺ , 100%), 111, 98, 97, 83,
69, 56.

Example 5 3,5-dimethylcyclopent-2-ene-2
- Manufacture of All-on (a) 29.5 g (77.5 mmol) of borax and 24.8 g (0.62 mmol) of sodium hydroxide are dissolved in 310 ml of water, and while cooling (17°C) 65 g (310 mmol)
3-carboethoxy-2-cyano-3,5-
Dimethylcyclopentanone [H. H. Stetter et al., Liebig's Annalen d.
Chem.1979, 944-949 from ethyl methacrylate and sodium cyanide]. 132.2 g of Calote dissolved in 428 ml of water (403
mmol) are added dropwise within 25 minutes at 13° C. to 19° C. and the mixture is stirred at room temperature for 3 hours. For working up, the mixture is acidified with 30 ml of sulfuric acid (2:1) and extracted four times with ethyl acetate. The organic phase is dried over sodium sulfate, concentrated and dried under high vacuum for 2 hours. 69.8g (100%) of 3-carboethoxy-2-cyano-2-hydroxy-
3,5-dimethylcyclopentanone is obtained in the form of a diastereomeric mixture. ^n20D ₌ 1.4658.

IR: 3400 (OH); 2270 (weak, CN); 1720 (broad, C=O); NMR (CDCl ₃ ): δ = 4.5-3.9 ppm multiplet/2 protons (ester CH ₂ ); 3-1.7 complex multiplet/4 protons (3 ring protons +
OH); 1.7-1.0 multiplet/9 protons (3×
_CH3 ); MS: 225 (M ⁺ ), 198, 180.

(b) The above 3-carboethoxy-2-cyano-2-
66.3 g (0.03 mol) of hydroxy-3,5-dimethylcyclopentanone and 30.2 g (0.4 mol) of anhydrous sodium acetate are treated with 350 ml of water. The mixture is refluxed for 6 hours. For working up, the mixture is adjusted to pH 7 with saturated sodium bicarbonate solution and then extracted four times with methylene chloride. The organic phase is dried over sodium sulfate, concentrated and dried under high vacuum for 1 hour. (However, this product can also be crystallized directly from the reaction mixture). 42.6 g (73%) of crystalline 2-carboethoxy-2,4-dimethylcyclopent-4-en-5-olone with a melting point of 92 DEG -93 DEG C. are obtained.

IR ( _CHCl3 ): 3540 and 3360 (OH); 1725
(COOC ₂ H ₅ ); 1670 (C=O); NMR (CDCl ₃ ): δ=6.1ppm single line, wide/
1 proton (OH); 4.14 quartet (J=7.4
Hz)/2 protons (O-CH ₂ -Me); 2.95
Double line x quartet (J ₁ = 17.6Hz, J ₂ = 1
Hz)/1 proton and 2.22 doublet x quartet (J ₁ = 17.6Hz, J ₂ = 1Hz) ~ proton (CH ₂ , C-3); 2.01 doublet x doublet (J ₁
= J ₂ = 1 Hz)/3 protons (CH ₃ , C-
4); 1.39 single line/3 protons (CH ₃ , C
-2); 1.20 triplet (J=7.4Hz)/3 protons (CH ₃ of ethyl ester).

MS: 198 (M ⁺ ), 180, 153, 141, 134, 124
(100%).

(c) 2-carboethoxy-2,4-dimethylcyclopent-4-ene-5-olone 4.8
g (24 mmol) with 48 ml of 2N sodium hydroxide solution and the mixture is stirred at room temperature for 1.5 hours. For work-up, the mixture is adjusted to pH 3 with 10% sulfuric acid and extracted three times with ethyl acetate.
The combined organic phases were dried over sodium sulfate and
Concentrate and dry under high vacuum for 2 hours. Melting point: 98°~
2-carboxy-2,4-dimethylcyclopent-4- at 105°C (with elimination of carbon dioxide)
3 g (58.5%) of en-5-olone are obtained.

IR (KBr): 3270 (broad, COOH); 1712 and 1690 (C=O); 1620 (C=C).

NMR (CD ₃ OD): δ = 5.9 ppm singlet, wide (DOH); 2.92 doublet x quartet (J ₁ = 17.2
Hz, J ₂ = 1 Hz) / 1 proton and 2.25 doublet x quartet (J ₁ = 17.2 Hz: J ₂ = 1 Hz) /
1 proton (CH ₂ , C-3); 1.97 doublet x doublet (J ₁ = J ₂ = 1Hz) / 3 protons (CH ₃ , C-4); 1.30 singlet / 3 protons (CH ₃ , C-2).

MS: 170 (M ⁺ ), 152, 134, 126, 124 (100%),
111.

(d) 85.1 g (0.5 mol) of the acid obtained according to paragraph (c), namely 2-carboxy-2,4-dimethylcyclopent-4-en-5-olone, in 10
% sulfuric acid and the mixture is refluxed for 45 minutes. For working up, the mixture is adjusted to pH 7 with 2N sodium hydroxide solution and then extracted three times with methylene chloride. The combined organic phases are dried over sodium sulphate and dried under high vacuum for 1 hour. Crystalline 3,5-dimethylcyclopent-2-en-2-olone 57.4, melting point 93°-94°C
g (91%) is obtained. This product is identical to the product obtained according to Example 4, paragraph (c).

Example 6 Direct treatment of 2-carboethoxy-2,4-dimethylcyclopent-4-ene-5-olone [see paragraph (b) of Example 5] under the above conditions results in the formation of The same product has a yield of 90
Obtained in %. This product melts at 93°-94°C.

Example 7 3-Carboethoxy-2-cyano-3,5-dimethylcyclopentanone [see paragraph (a) of Example 5] was treated with Caloto and the resulting mixture was
The same product as that of Example 5, paragraph (d) can also be obtained by acidifying the mixture to 50% and then refluxing the mixture for 24 hours. When processed as described in paragraph (d) of Example 5, the melting point is 92° to 93°C (from water).
pure crystalline 3,5-dimethylcyclopentate
2-ene-5-allone (70%) is obtained.

Example 8 3,5-diethylcyclopent-2-ene-2
-Preparation of All-On (a) When ethyl 2-ethyl acrylate is used in place of ethyl methacrylate, 3-carboethoxy-2-cyano-3,5-diethylcyclopentanone is produced by H. Stetzter et al., Liebig's Annalen
d.Chem.1979, 944 in a yield of 80%.
This 3-carboethoxy-2-cyano-3,5
-Diethylcyclopentanone is 95° to 116°C/
Boil at 10.05 torr.

IR: 2260 and 2210 (CN), 1755 (C=O),
1728 (COOE _t ); NMR (CDCl ₃ ): δ = 4.26 ppm quartet/2 protons (ester CH ₂ ), 4.0-3.1 various singlets/1 proton (H of C ₂ ) of diastereomers; 2.8-1.3 multiplet/7 protons (3 remaining ring protons and 2 ethyl
CH ₂ ); 1.3 triplet/3 protons (ester
CH ₃ ); 0.95 triplet/6 protons (2 ethyl CH ₃ ); MS: 237 (M ⁺ ), 208, 192, 180, 163, 152,
142, 135 (100%), 126, 106.

Oxidation of this nitrile with Caloto in a manner analogous to that described in paragraph (a) of Example 5 and work-up yields 3-carboethoxy-2-cyano-2-hydroxy-3,5-diethylcyclopentane. is obtained in quantitative yield, n ²⁰ _D =
1.4502.

IR: 3350 (OH), 2250 (weak, CN), 1730 (broad, ketone + ester); MS: 253 (M ⁺ ), 237, 226, 208, 181, 152
(100%), 141, 129, 124, 109.

(b) The cyanohydrin obtained according to paragraph (a) is refluxed in aqueous solution and worked up according to the procedure described in paragraph (b) of Example 5. 2-carboethoxy-2,4-diethyl-cyclopent-4
-ene-5-olone is obtained in 80% yield.

IR: 3360 (OH), 1725 (COOC ₂ H ₅ ), 1705 (C=
O), 1655 (C=C); NMR (CDCl ₃ ): δ = 6.0 ppm, single line, broad/1 proton (OH); 4.18 quartet/2 protons (ester CH ₂ ); 2.95 doublet/ 1
Protons and 2.35 doublets/1 proton and 2.35 doublets/1 proton (CH ₂ at C-3); 2.7 to 1.5 multiplets/4 protons (2×CH ₂ , ethyl); 1.4 to 0.7 multiplets/9 Proton (3×CH ₃ ); MS: 226 (M ⁺ ), 197, 181, 162, 152 (100%),
137, 124, 109.

(c) Crystalline 2-carboxy-2,4-
-Diethylcyclopent-4-en-5-olone is obtained in a yield of 71%.

IR: 3520 (OH), 3200 (wide, COOH), 1705
(Broad, C=O Ketone, Ester) 1655
(C=C); NMR (CDCl ₃ ): δ = 7.9 ppm singlet/2 protons (OH, COOH); 3.06 doublet/1 proton and 2.4 doublet/1 proton (CH ₂ ,
C-3); 2.8 to 1.5 triplet/4 protons (2 x ethyl CH ₂ ); 1.17 triplet/3
Protons and 0.9 triplet/3 protons ( _2xCH3 ); MS: 169, 154, 126 (100%), 111, 108.

When the above acids are heated or left to stand, they decompose and their melting point
3,5-diethylcyclopentate at 38.5° to 39°C
2-en-2-all on.

Claims (1)

[Claims] 1. General formula [wherein R represents a methyl or ethyl group,
R′ represents a hydrogen atom, methyl or ethyl group,
X is an oxygen atom, a group >CH ₂ , >CH—CH ₃ , or >
(representing CHC ₂ H ₅ ), a method for producing a compound having the general formula (In the formula, R, R' and X are as defined above, and R'' represents a hydrogen atom, or if
COOR (where R is a hydrogen atom or C _1-6 -
(which may represent an alkyl group) is subjected to cyanohydrin decomposition, and any possible groups - COOR are eliminated.
The above method. 2. The method according to claim 1, wherein R'' in the formula represents a hydrogen atom. 3. The method according to claim 1, wherein R'' in the formula represents a group -COOR.