JPH1149722A - Production of biphenyl derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively produce the subject derivative useful as an intermediate for medicines, agrochemicals, liquid crystals, heat-resistant polymers or the like from an inexpensive raw material by reacting a specific cyclohexenone derivative with a halogenating agent in (or without) a solvent and then carrying out an eliminating reaction of the halogen atom in the presence of a base in (or without) a solvent. SOLUTION: A compound represented by formula I (X is H or the like; Y is CO2 or the like) is reacted with methyl vinyl ketone in the presence of a condensing agent in (or without) a solvent to synthesize a compound represented by formula II. A cyclizing reaction is then carried out in the presence of the condensing agent in (or without) a solvent to produce a cyclohexenone derivative represented by formula III, which is then reacted with a halogenating agent in (or without) a solvent to form a compound represented by formula IV or the like. The halogen atom of the resultant compound represented by formula IV or the like is further eliminated in the presence of a base in (or without) a solvent to afford the objective derivative represented by formula V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the production of biphenyl derivatives useful as intermediates for pharmaceuticals and agricultural chemicals, liquid crystals, heat-resistant polymers, liquid crystalline polymers and the like.

[0002]

2. Description of the Related Art Hitherto, as a method for producing a biphenyl derivative, 1) a method based on the Ullman reaction (Japanese Patent Laid-open No.
7564), 2) A method of coupling an organometallic compound and an aryl halide compound in the presence of a catalyst such as a Pd complex (Japanese Unexamined Patent Publication (Kokai) No. 5-97913, 6-234690), 3)
Method for coupling an aryl halide compound in the presence of a Ni catalyst and metal powder (JP-A-6-6515)
3), 4) A method of synthesizing a tetrahydrobiphenyl derivative by cyclizing an α-cyanocinnamic acid ester with butadiene, followed by dehydrogenation and decarboxylation (JP-A-9-87238) is known. ing.

[0003]

The conventional methods involve a reaction under anhydrous conditions using an organometallic compound or the like, a reaction under high-temperature and high-pressure conditions, and require an expensive catalyst or the like in terms of production equipment and cost. There were many problems in terms of surface. Furthermore, since the selectivity of the reaction is not always high, there are also problems such as generation of many by-products and complicated isolation and purification.

[0004]

SUMMARY OF THE INVENTION The present invention provides a novel process for the selective production of biphenyl compounds using inexpensive raw materials under mild reaction conditions.

That is, the general formula (1)

[0006]

Embedded image

Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ An alkyl group, except that X is H and Y is CO ₂ Me or CO ₂ Et).

[0008]

Embedded image

Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ An alkyl group, except that X is H and Y is CO ₂ Me or CO ₂ Et.)

[0010]

Embedded image

Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ An alkyl group, except that X is H and Y is CO ₂ Me or CO ₂ Et), and a cyclohexenone derivative represented by the general formula (4a) or (4b)

[0012]

Embedded image

Cyclohexadiene derivatives represented by the general formula (5)

[0014]

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(Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ Which represents an alkyl group).

In the general formulas (1) to (4) of the present invention, X represents, for example, hydrogen, methyl, ethyl, propyl, butyl, methoxy, ethoxy, propoxy, butoxy and the like. And preferably a methyl group, and the substitution position is preferably the para position. Y
Examples thereof include a cyano group, a carboxylic acid group, a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, a butoxycarbonyl group, and the like. Preferred are a cyano group, a methoxycarbonyl group, and an ethoxycarbonyl group.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The reaction steps are as follows.

[0018]

Embedded image

(In the figure, X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ In the general formulas (1) and (2), X is H, Y is CO ₂ Me, and CO ₂ E is an alkyl group, and Z is a halogen atom.
Except for the case of t. )

First step: Production of compound of general formula (2) from compound of general formula (1): general formula (2)

[0021]

Embedded image

(Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ Represents an alkyl group, except that X is H and Y is CO ₂ Me or CO ₂ Et).

[0023]

Embedded image

(Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ Represents an alkyl group, provided that X is H and Y is CO ₂ Me or CO ₂ Et.) The compound can be produced by reacting a compound with methyl vinyl ketone in a solvent or in the absence of a solvent in the presence of a base. it can.

Examples of the solvent used in the above reaction include aliphatic lower alcohols such as methanol and ethanol, aromatic hydrocarbons such as toluene, ether hydrocarbons such as tetrahydrofuran, organic chlorine hydrocarbons such as dichloromethane, dimethylformamide, and the like. Aprotic polar solvents such as dimethyl sulfoxide, water and mixtures thereof. Preferably, aliphatic lower alcohols, aromatic hydrocarbons, ether hydrocarbons, water, and mixtures thereof are used. The reaction temperature is usually from −20 ° C. to the solvent reflux temperature, preferably from 0 ° C. to the solvent reflux temperature.

Examples of the condensing agent include bases, acids, transition metal compounds and the like. As the base, for example, KOH, Na
Alkali metal hydroxides such as OH, K ₂ CO ₃ , Na ₂
Alkali metal carbonates such as CO ₃ , MeONa, EtO
Alkali metal salts of aliphatic lower alcohols such as Na and t-BuOK; alkali metal hydrides such as NaH; organic bases such as pyridine and triethylamine; preferably alkali metal hydroxides, alkali metal carbonates and aliphatic lower salts Alkali metal salts of alcohols, organic bases.
The amount used is usually 0.001 to 5 equivalents,
Preferably it is 0.005 to 3 equivalents. Examples of the acid include inorganic acids such as sulfuric acid and hydrochloric acid, and organic acids such as acetic acid. Transition metal compounds include Yb (OTf) ₃ , Eu
Cl ₃ , Ni (acac) _{2 and the} like. The use amount is usually 0.001 to 5 equivalents, preferably 0.0
05 to 0.5 equivalent.

Step 2: Preparation of a compound of the general formula (3) from a compound of the general formula (2):

[0028]

Embedded image

Wherein X is H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y is CO ₂ R or CN, and R is H or C ₁ -C ₄ Represents an alkyl group, except that X is H and Y is CO ₂ Me or CO ₂ Et.

[0030]

Embedded image

Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ A compound wherein X is H and Y is CO ₂ Me or CO ₂ Et) is subjected to a cyclization reaction in the presence or absence of a base or acid in a solvent or without a solvent. It can be manufactured by the following.

Examples of the solvent used in the above reaction include aliphatic lower alcohols such as methanol and ethanol, aromatic hydrocarbons such as toluene, ether hydrocarbons such as tetrahydrofuran, organic chlorine hydrocarbons such as dichloromethane, dimethylformamide, and the like. Aprotic polar solvents such as dimethyl sulfoxide, water and mixtures thereof. Preferably, aliphatic lower alcohols, aromatic hydrocarbons, ether hydrocarbons, water, and mixtures thereof are used. The reaction temperature is usually from 0 ° C. to the solvent reflux temperature, preferably from 20 ° C. to the solvent reflux temperature.

As the base, for example, alkali metal hydroxides such as KOH and NaOH, K ₂ CO ₃ , Na ₂ CO ₃
Alkali metal carbonates such as MeONa, EtONa,
alkali metal salts of aliphatic lower alcohols such as t-BuOK, alkali metal hydrides such as NaH, pyridine,
Organic bases such as triethylamine, pyrrolidine, piperidine and the like, preferably alkali metal hydroxides, alkali metal carbonates, alkali metal salts of aliphatic lower alcohols, and organic bases. The amount used is usually 0.00
It is 1 to 5 equivalents, preferably 0.01 to 3 equivalents. The acid is an organic acid such as formic acid or acetic acid, or an inorganic acid such as hydrochloric acid or sulfuric acid, and is preferably an organic acid. The amount used is usually 0.001 to 5 equivalents, preferably 0.01 to 3 equivalents. The above bases and acids can be used as a mixture, and are preferably mixed with an organic base and an organic acid.

Third step: Preparation of general formula (4a) or (4b) or a mixture thereof from compound of general formula (3): general formula (4a) or (4b)

[0035]

Embedded image

(Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ Represents an alkyl group.) Or a mixture thereof has the general formula (3)

[0037]

Embedded image

Wherein X is H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y is CO ₂ R or CN, and R is H or C ₁ -C ₄ Which represents an alkyl group)) in a solvent or without a solvent with a halogenating agent.

Examples of the solvent used in the above reaction include aromatic hydrocarbons such as toluene, ether hydrocarbons such as tetrahydrofuran, organic chlorine hydrocarbons such as dichloromethane, aliphatic hydrocarbons such as n-hexane, and mixtures thereof. Is mentioned. Preferably, aromatic hydrocarbons, organic chlorinated hydrocarbons, aliphatic hydrocarbons and mixtures thereof are used. The reaction temperature is usually from −20 ° C. to the solvent reflux temperature, preferably from 0 ° C. to the solvent reflux temperature. Examples of the type of the halogenating agent include oxalyl chloride, thionyl chloride, and phosphorus oxychloride, and oxalyl chloride is preferable. The amount used is usually 0.5 to 10 equivalents, preferably 1 to 5 equivalents.

Fourth step: General formula (4a) or (4b)
Or production of a compound of general formula (5) from a mixture thereof: general formula (5)

[0041]

Embedded image

Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ A compound represented by the general formula (4a) or (4b)

[0043]

Embedded image

(Wherein X represents H, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group, Y represents CO ₂ R or CN, and R represents H or C ₁ -C ₄ Or a mixture thereof with a base in a solvent or without a solvent.

Examples of the solvent used in the above reaction include aliphatic lower alcohols such as methanol and ethanol, aromatic hydrocarbons such as toluene, ether hydrocarbons such as tetrahydrofuran, organic chlorine hydrocarbons such as dichloromethane, dimethylformamide, and the like. Dimethyl sulfoxide, water and mixtures thereof. Preferably,
Examples include aliphatic lower alcohols, aromatic hydrocarbons, ether hydrocarbons, water, and mixtures thereof. The reaction temperature is usually from −20 ° C. to the solvent reflux temperature,
The temperature is from ℃ to the reflux temperature of the solvent.

Examples of the base include alkali metal hydroxides such as KOH and NaOH, K ₂ CO ₃ and Na ₂ CO ₃
Alkali metal carbonates such as MeONa, EtONa,
alkali metal salts of aliphatic lower alcohols such as t-BuOK, alkali metal hydrides such as NaH, pyridine,
Organic bases such as triethylamine are preferred, and alkali metal hydroxides, alkali metal carbonates and alkali metal salts of aliphatic lower alcohols are preferred. The amount used is usually 0.5 to 20 equivalents, preferably 1 to 1 equivalent.
It is 0 equivalent.

[0047]

The present invention will be described more specifically with reference to the following examples. Example 1 Preparation of ethyl 2-((4-methylphenyl) carbonyl) -5-oxohexanoate 2.28 g of 4'-methylbenzoylacetic acid ethyl ester
11 mg (0.16 mmol) of sodium ethoxide was added to an ethanol solution (10 ml) of (11.1 mmol), and 2.0 g (27.8 mmol) of methyl vinyl ketone was added.
1) was slowly added dropwise at 25 ° C. or lower under cooling. The mixture was stirred at the same temperature for 4 hours. After distilling off ethanol under reduced pressure, the mixture was acidified by adding dilute hydrochloric acid, and extracted with ethyl acetate. The organic layer was washed with brine and dried over anhydrous magnesium sulfate. Then, anhydrous magnesium sulfate was filtered, and the solvent was distilled off under reduced pressure to obtain a residue. This was purified by silica gel column chromatography (hexane-ethyl acetate system) to obtain the desired product as a pale yellow oil. (2.73 g, yield 89.0%)

¹ H-NMR (ppm, 300 MHz, C
DCL ₃ ) δ 7.92 (2H, d, J = 8.0 Hz),
7.28 (2H, d, J = 8.0 Hz), 4.41 (1
H, t, J = 7.0 Hz), 4.14 (2H, q, J =
6.9 Hz), 2.55 to 2.60 (2H, m), 2.
42 (3H, s), 2.20 to 2.25 (2H, m),
2.13 (3H, s), 1.17 (3H, t, J = 6.
9Hz)

Example 2 Preparation of 2-((4-methylphenyl) carbonyl) -5-oxohexanenitrile 1.0 g of 4'-methylbenzoylacetonitrile (6.
To a toluene solution (29 mmol) of 29 mmol) was added 1.0 ml (12.6 mmol) of methyl vinyl ketone and 0.088 ml (0.63 mmol) of triethylamine, and the mixture was stirred at room temperature for 24 hours. After evaporating the solvent under reduced pressure, the obtained residue was purified by silica gel column chromatography (hexane-ethyl acetate system) to obtain the desired product as a pale yellow oil. (1.0 g, 69.4% yield)

¹ H-NMR (ppm, 300 MHz, C
DCL ₃ ) δ 7.95 (2H, d, J = 8.0 Hz),
7.33 (2H, d, J = 8.0 Hz), 4.64 (1
H, dd, J = 9.1, 5.1 Hz), 2.78-2.
89 (2H), 2.44 (3H, s), 2.30-2.
40 (1H, m), 2.21 (3H, s), 2.03 to
2.16 (1H, m)

Example 3 Preparation of ethyl 2- (4-methylphenyl) -4-oxocyclohex-2-enecarboxylate Ethyl 2-((4-methylphenyl) carbonyl) -5-oxohexanoate 4 .19 g (15.2 mm
ol) in a toluene solution (10 ml) of 137 mg of acetic acid
(2.28 mmol) and 129 mg of piperidine (1.
52 mmol) and heated at 110 ° C. for 9 hours.
After cooling to room temperature, ethyl acetate was added, and the mixture was washed with dilute hydrochloric acid and saturated saline. The organic layer was dried over anhydrous magnesium sulfate, then filtered, and the solvent was distilled off under reduced pressure to obtain a residue. This was purified by silica gel column chromatography (hexane-ethyl acetate system) to obtain the desired product as a brown oil. (3.46 g, 88.0 yield)
%)

¹ H-NMR (ppm, 300 MHz, C
DCl ₃ ) δ 7.41 (2H, d, J = 8.2 Hz),
7.21 (2H, d, J = 8.2 Hz), 5.47 (1
H, s), 4.11 (2H, q, J = 7.0 Hz),
3.96 (1H, dd, J = 4.8, 4.8 Hz),
2.55 to 2.65 (1H, m), 2.40 to 2.55
(3H), 2.38 (3H, s), 1.14 (3H,
t, J = 7.0 Hz)

Example 4 Preparation of ethyl 2-phenyl-4-oxocyclohex-2-enecarboxylate Ethyl 2-phenylcarbonyl-5-oxohexanoate (3.87 g, 14.8 mmol) in toluene (5 ml) )), 130 mg (2.17 mmol) of acetic acid and 127 mg (1.49 mmol) of piperidine were added, and the mixture was heated at 110 ° C for 5 hours. After cooling to room temperature, ethyl acetate was added, and the mixture was washed with dilute hydrochloric acid and saturated saline. The organic layer was dried over anhydrous magnesium sulfate, then filtered, and the solvent was distilled off under reduced pressure to obtain a residue. Purification by silica gel column chromatography (hexane-ethyl acetate system) gave the desired product as a brown oil.
(4.02 g, yield 94.7%)

¹ H-NMR (ppm, 300 MHz, C
DCl ₃ ) δ 7.50 (2H, d, J = 3.0, 6.4)
Hz), 7.40 to 7.48 (3H), 6.47 (1
H, s), 4.11 (2H, q, J = 7.0 Hz),
3.96 (1H, dd, J = 3.7, 3.7 Hz),
2.60 to 2.70 (1H, m), 2.35 to 2.55
(3H), 1.12 (3H, t, J = 7.0 Hz)

Example 5 Preparation of a mixture of ethyl 4-chloro-2-phenylcyclohexa-2,4-dienecarboxylate and ethyl 4-chloro-2-phenylcyclohexa-1,3-dienecarboxylate Ogisalyl chloride 2.5 was added to a toluene solution (10 ml) of -phenyl-4-oxocyclohex-2-enecarboxylic acid ethyl ester 1.24 g (5.1 mmol).
8 mg (20.4 mmol) and add 2 mg at 70-75 ° C.
The mixture was heated and stirred for an hour. Then, the mixture was cooled to room temperature, ethyl acetate was added, and the mixture was washed sequentially with water, a saturated aqueous solution of sodium hydrogencarbonate and saturated saline. The organic layer was dried over anhydrous magnesium sulfate, then filtered, and the solvent was distilled off under reduced pressure to obtain the desired product as a pale yellow oil. (1.24
g, yield 93.0%)

¹ H-NMR (ppm, 300 MHz, C
_{DCl 3) δ7.25~7.45 (8H),} 7.13~
7.16 (2H), 6.35 (1H, s), 6.19
(1H, s), 5.87 (1H, brs), 4.09
(2H, q, J = 7.3 Hz), 3.93 (2H, q,
J = 7.3 Hz), 3.64 (1H, dd, J = 3.
3,8.6 Hz), 2.90 to 3.05 (1H, m),
2.60 to 2.85 (5H), 1.34 (3H, t, J
= 7.3 Hz), 0.89 (3H, t, J = 7.3H)
z)

Example 6 Preparation of ethyl 2-biphenylcarboxylate and 2-biphenylcarboxylic acid Ethyl 4-chloro-2-phenylcyclohexa-2,4-dienecarboxylate and 4-chloro-2-phenylcyclohexa To a methanol solution (5 ml) of 0.62 g (2.54 mmol) of a mixture of -1,3-dienecarboxylic acid ethyl ester was added sodium methoxide (28%
1.98 g (10.1 mmol) of a methanol solution) was added, and the mixture was stirred at room temperature for 17 hours. After distilling off methanol under reduced pressure, dilute hydrochloric acid was added and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated saline, dried over anhydrous magnesium sulfate, and filtered, and then the solvent was distilled off under reduced pressure to obtain a crude target compound. Then, it was purified and separated by silica gel column chromatography (hexane-ethyl acetate system) to give 2-biphenylcarboxylic acid ethyl ester (136 mg, yield 23.7%) and 2-biphenylcarboxylic acid (236 mg, 53.8%).

2-biphenylcarboxylic acid ethyl ester ¹ H-NMR (ppm, 300 MHz, CDCl ₃ ) δ
7.79 (1H, d, J = 8.3 Hz), 7.35-
3.40 (5H), 7.26 to 7.30 (3H),
07 (2H, d, J = 7.0 Hz), 0.98 (3H,
t, J = 7.0 Hz)

2-biphenylcarboxylic acid ¹ H-NMR (ppm, 300 MHz, CDCl ₃ ) δ
7.91 (1H, d, J = 8.2 Hz), 7.17-
7.42 (8H)

[0060]

According to the present invention, it is possible to selectively produce a biphenyl derivative which is useful as an intermediate such as a medicinal and agricultural chemical, a liquid crystal, a heat-resistant polymer and a liquid crystalline polymer. This synthesis method can provide a selective industrial production method of a biphenyl derivative using inexpensive raw materials and not requiring special equipment or reaction conditions.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C07C 67/333 C07C 67/333 69/757 69/757 Z 255/46 255/46

Claims (7)

[Claims] 1. A compound of the general formula (1) (Wherein X is H, a C ₁ -C ₄ alkyl group or C ₁ -C ₄
And Y represents CO ₂ R or CN;
R represents an alkyl group of H or C ₁ -C _4. However, the case where X is H and Y is CO ₂ Me and CO ₂ Et is excluded. ) Is reacted with methyl vinyl ketone in a solvent or without solvent in the presence of a condensing agent to give a compound of the general formula (2) (Wherein X is H or a C ₁ -C ₄ alkyl group or C ₁ -C 4
_{4 represents} an alkoxy group, Y represents CO ₂ R or CN, and R represents H or a C ₁ -C ₄ alkyl group. However, the case where X is H and Y is CO ₂ Me and CO ₂ Et is excluded. )
After synthesizing a compound represented by the general formula (3), a cyclization reaction is further carried out in the presence of a condensing agent in a solvent or in the absence of a solvent. (Wherein X is H or a C ₁ -C ₄ alkyl group or C ₁ -C 4
_{4 represents} an alkoxy group, Y represents CO ₂ R or CN, and R represents H or a C ₁ -C ₄ alkyl group. However, the case where X is H and Y is CO ₂ Me and CO ₂ Et is excluded. )
A method for producing a cyclohexenone derivative represented by the formula: 2. A compound of the general formula (3) (Wherein X is H, a C ₁ -C ₄ alkyl group or C ₁ -C ₄
And Y represents CO ₂ R or CN;
R represents an alkyl group of H or C ₁ -C _4. ) Is reacted with a halogenating agent in a solvent or without solvent to obtain a compound represented by the general formula (4a) or (4).
b) embedded image (Wherein X is H, a C ₁ -C ₄ alkyl group or C ₁ -C ₄
And Y represents CO ₂ R or CN;
R represents an alkyl group of H or C ₁ ~C _4, Z is a halogen atom. Or a mixture thereof, followed by elimination of a halogen atom in the presence of a base in a solvent or in the absence of a solvent, characterized by the following general formula (5): (Wherein X is H, a C ₁ -C ₄ alkyl group or C ₁ -C ₄
And Y represents CO ₂ R or CN;
R represents an alkyl group of H or C ₁ -C _4. )). 3. The method according to claim 1, wherein the compound has the general formula (3) (Wherein X is H, a C ₁ -C ₄ alkyl group or C ₁ -C ₄
And Y represents CO ₂ R or CN;
R represents an alkyl group of H or C ₁ -C _4. However, the case where X is H and Y is CO ₂ Me and CO ₂ Et is excluded. )), And then the general formula (5) according to the method of claim 2. (Wherein X is H, a C ₁ -C ₄ alkyl group or C ₁ -C ₄
And Y represents CO ₂ R or CN;
R represents an alkyl group of H or C ₁ -C _4. )). 4. The method of claim 1, wherein X is methyl and Y is CN.
The production method according to any one of claims 1 to 3. 5. X is methyl and Y is CO ₂ Me or C
The production method according to claim 1, wherein the production method is O ₂ Et. 6. A compound of the general formula (3) (Wherein X is H, a C ₁ -C ₄ alkyl group or C ₁ -C ₄
And Y represents CO ₂ R or CN;
R represents an alkyl group of H or C ₁ -C _4. However, the case where X is H and Y is CO ₂ Me and CO ₂ Et is excluded. ). 7. A compound of the formula (4a) or (4b) (Wherein X is H, a C ₁ -C ₄ alkyl group or C ₁ -C ₄
And Y represents CO ₂ R or CN;
R represents an alkyl group of H or C ₁ ~C _4, Z is a halogen atom. ) Or an intermediate represented by a mixture thereof.