GB2123814A

GB2123814A - Novel intermediates

Info

Publication number: GB2123814A
Application number: GB08312570A
Authority: GB
Inventors: Barry Peter Clark; William James Ross; Alec Todd
Original assignee: Lilly Industries Ltd
Current assignee: Lilly Industries Ltd
Priority date: 1979-04-05
Filing date: 1980-04-03
Publication date: 1984-02-08
Also published as: PL223229A1; AT368499B; NZ193343A; GB2123814B; ES490122A0; FR2453168A1; DE3012597A1; ATA181880A; CA1142944A; ES8104268A1; PH14895A; US4364956A; BE882644A; FI801020A; DK142180A; AR225918A1; AU535315B2; CS214826B2; NL8002025A; SE8002515L

Description

1

GB 2 123 814 A 1

SPECIFICATION Novel intermediates

This invention relates to intermediates useful for the preparation of novel pyranone compounds with pharmaceutical properties.

5 The invention comprises compounds of the formula 5

(R8),N R3 0

\ X

c=c—c

/ \

R2 CHZR4

in which R2 is hydrogen, orC^ alkyl; R3 is a group of the formula R6—(Z)m—where m is 0 or 1, Z is 0, S, SO, S02 or CO, and R6 is phenyl optionally substituted by one or more groups selected from halogen, C1_4alkyl, C3_6cycloalkyl, C^alkoxy, benzyloxy, hydroxy, nitro, C1_4alkylthio, C1_4alkylsulphinyl, 10 C,_4alkylsulphonyl, amino and NHR7 where R7 is C2_6acyi; R4 is hydrogen or C^galkyl; and each R8 is 10 Chalky! or (R8)ZN is a saturated heterocyclic ring.

These are useful intermediates in the preparation of compounds of formula

R3,

X / \ /R

\/V

(I)

in which R1 is COOR5, CONHR5, cyano, 5-tetrazolyl or 5-tetrazolylaminocarbonyl, where R5 is hydrogen 15 or C^e alkyl optionally substituted in the case of COOR5 to provide an ester group that readily cleaves 1 5 to give the free acid; R2 is hydrogen or C,^ alkyl; R3 is a group of the formula R6—(Z)m—

where m is 0 or 1, Z is 0, S, SO, S02 or CO, and R6 is phenyl optionally substituted by one or more groups selected from halogen, C,_4 alkyl, C3_6 cycloalkyl, C,_4 alkoxy, benzyloxy, hydroxy, nitro, C,_4 alkylthio, C,_4 alkylsulphinyl, Ct_4 alkylsulphonyl, amino and NHR7 where R7 is C2_6 acyl; and R4 is 2.0 hydrogen, C^g alkyl or halogen, and salts thereof; which have useful pharmaceutical properties. 20

When reference is made to C^e alkyl of C^ acyl groups it is intended to include both straight and branched chain groups, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n-pentyl and n-hexyl, the most preferred groups being methyl and ethyl and the corresponding acyl groups derived from them. In the case where R1 is COOR5 and R5 is alkyl, it is to be understood that 25 alkyl groups can be optionally substituted, in view of the fact that it is often merely necessary to attach 25 an ester group that readily cleaves to give the free acid, and examples of such substituted alkyls include acetoxymethyl, methylthiomethyl, methylsulphinylmethyl and methylsulphonylmethyl.

The term, halogen, refers to fluorine, chlorine, bromine or iodine, and is especially chlorine or bromine.

30 When reference is made to substituted phenyl, there can be one or more substituent on the 30

nucleus, such as 1 to 3 substituents and preferably a single substituent. A C3_6 cycloalkyl group is preferably cyclopropyl or cyclohexyl and when the substituent is Ct_4 alkoxy, C,_4 alkylthio, C,_4 alkylsulphinyl C,_4 alkylsulphonyl, the C,_4 alkyl group may be any of the examples listed above and is preferably methyl or ethyl. A group of the formula NHR7 is preferably acetamido.

35 Included in the above general formula (I) are the salts of compounds, for example, those in which 35 R1 is COOH or 5-tetrazolyl, or compounds in which acidic or basic groups are attached to the substituent R6. The acid addition salts are preferably the pharmaceutically-acceptable, non-toxic addition salts with suitable acids, such as those with inorganic acids, for example hydrochloric,

hydrobromic, nitric, sulphuric or phosphoric acids, or with organic acids, such as organic carboxylic 40 acids, for example, glycollic, maleic, hydroxymaleic, fumaric, malic, tartaric, citric, salicylic, o- 40

acetoxybenzoic, nicotinic or isonicotinic acid, or organic sulphonic acids for example methane sulphonic, ethane sulphonic, 2-hydroxyethane sulphonic, toluene-p-sulphonic or naphthaiene-2-sulphonic acid. The salts of acid compounds are preferably pharmaceutically-acceptable, non-toxic,

salts of suitable mineral bases, such as alkali metal hydroxides especially the potassium or sodium 45 salts, or alkaline earth metal hydroxides especially the calcium salts, or of organic bases such as 45

amines. Apart from the pharmaceutically-acceptable salts, other salts are included, such as for example, those with picric or oxalic acid; they may serve as intermediates in the purification of the compounds or in the preparation of other, for example, pharmaceutically-acceptable, salts or are useful for the purpose of identification, characterization or purification.

2

GB 2 123 814 A 2

In the above formula (I), some of the preferred groups are those which include one or more of the following features

(a) R1 is COOR5, CONHR5 or 5-tetrazolyl

(b) R1 is COOR5 where R5 is hydrogen or C.,_6 alkyl

5 (c) R2 and R4 are both hydrogen 5

(d) R3 is of the formula R6—(Z)m—

where m is 0 or m is 1 and Z is 0 or CO

(e) R6 is phenyl optionally substituted by 1 to 3 substituents selected from halogen, C,_4 alkyl,

methoxy, benzyloxy and hydroxy

10 (f) R4 is hydrogen or C,_6 alkyl 10

One preferred group of compounds of formula (I) is of the following formula t

I I ""

*-\/v in which R1 is COOR5 or CONHR5, where R5 is hydrogen or C.,_6 alkyl, and R3 is a group of the formula R6—(Z)m— where m is 0 or 1, Z is 0, S or CO and R6 is phenyl optionally substituted by halogen,

15 methyl, methoxy or hydroxy, or a salt thereof. 15

A further preferred group is one of formula (II) in which R3 is a group of the formula R6—(Z)m—

where m is 0 or 1, Z is 0 or CO and R6 is phenyl optionally substituted by halogen, methyl, methoxy or hydroxy.

The compounds of formula (I) are prepared by a method which comprises reacting a compound of 20 formula 20

(IN

/\

• •

If II • •

(R8)^ '0HX COOR5

where R8 is C^ alkyl or (R8)2N is a saturated heterocyclic ring such as morpholino, piperidino or pyrrolidino, with acid, optionally followed by conversion of the COOR5 group into another R1 substituent or by the introduction of one or more substituent in the R6 group. The reaction can be 25 carried out in both aqueous and non-aqueous conditions, preferably employing a mineral acid, such as 25 for example hydrochloric acid or sulphuric acid, at a temperature of from 0°C to 100°C, more especially from 10°C to 50°C.

When it is desired to prepare a compound of formula (I) in which R4 is halogen a compound of formula (III) in which R4 is hydrogen can be reacted with halogen which causes liberation of hydrogen 30 halide and ring closure to give the final halogenated product of formula (I). 30

Compounds of formula (111) are conveniently formed, without isolation, by reaction of a compound of formula (IV)

(R8),N R3 0

\ I X

C=C— C (IV)

/ \

R2 CH2R4

where R4 is hydrogen or C^e alkyl, with a dialkyl oxalate of formula (C00R5)2 in the presence of a base. 35 The product of this reaction may then be acidified and ring closure effected without the isolation of an 35 intermediate of formula (III).

Reaction of dialkyl oxalate with a compound of formula (IV) is preferably performed in an organic solvent such as an alcoholic or ethereal solvent, for example ethanol, ether or dimethoxyethane,

preferably at a temperature of from 0°C to 100°C. The reaction requires the presence of a base such 40 as an alkali metal alkoxide. 40

The intermediate of formula (IV) can readily be obtained by two alternative routes. In the first route, a ketone of formula (V)

R3—CH2—CO—CHZ—R4

(V)

3

GB 2 123 814 A 3

is reacted with a dialkylamide dialkylacetal of formula (VI)

(R8)2N—C(R2)(OR9)2 (VI)

where R9 is C^g alkyl. The reaction is preferably carried out at a temperature in the range of from 0°C to 100°C. The amide acetals of formula (VI) are prepared by known methods such as alkylation of 5 amides of formula R2CON(R8)2 with for example trialkyl oxonium fluoroborates of the formula (R9)3OBF4, followed by treatment of the resulting complexes with alkali metal alkoxides.

The second route for preparing compounds of formula (IV) consists in acylating a compound of formula (VII)

R3—CH=CR2N(R8)2 (VII)

10 under conditions typical of acylation reactions, for example at a temperature of from 0°C to 150°C. Suitable acylating agents are of the formula R4CH2COX where X is halogen, especially chlorine, or (R4CH2C0)20. The enamines (VII) can be prepared by reacting the appropriate acetaldehyde with a diaikyiamine in the presence of a base, for example potassium carbonate.

It will be appreciated that compounds prepared by the above process in which R1 is COOR5 where 15 Rs is hydrogen or C^g alkyl can readily be converted into compounds with other R1 substituents, as follows:

Compounds in which R1 is COOR® where R5 is C^g alkyl, can be converted to the corresponding free acid in which R1 is COOH by hydrolysis in the presence of acid such as a mineral acid, for example hydrochloric acid, or by reaction with boron trihalide in an inert solvent, with lithium iodide in DMF, or 20 with sodium iodide in a mixture of methyl ethyl ketone and pyridine. Such methods are well known in the art. Conversely, compounds in which R1 is COOR5 where R5 is C.,_6 alkyl can be prepared from the free acid by esterification of the free carboxyl group with the appropriate alcohol or by treatment with alkyl halide in the presence of base. Salts of the free acid can, of course, be prepared simply by reaction with alkali.

25 Compounds in which R1 is CONHR5 can be prepared by reacting a compound in which R1 is

COOR5 where R5 is C,_6 alkyl, with ammonia or the appropriate amine of formula R5NH2, or they can be prepared by the reaction of ammonia or an amine of formula R5NH2 with the appropriate acyl chloride, which can in its turn be derived from the free carboxyl derivative by the reaction of thionyl chloride. Such reactions are well known in the art.

30 Compounds in which R1 is CN can be prepared by dehydration of the amides in which R1 is C0NH2, a convenient dehydrating agent being, for example, a mixture of triphenylphosphine and carbon tetrachloride.

Compounds in which R1 is 5-tetrazolyl can be prepared by reaction of the cyano derivative prepared above with, for example sodium azide and ammonium chloride in dimethylformamide. Salts 35 can be prepared from the 5-tetrazolyl derivatives by the addition of base according to standard techniques.

It will also be appreciated that many of the compounds of formula (I) can be converted one to another by introduction of groups into the R6 nucleus employing simple and well known chemical reactions. When a nitro substituent is desired in the R6 group, the unsubstituted compound can be 40 nitrated with a mixture of concentrated nitric and sulphuric acids by conventional method. The nitro compound can subsequently be converted to other substituents such as amino or acylamino. The amino compound may be diazotised and the resultant diazonium salt converted to a variety of other products, for example, by decomposition in an alcohol to yield the corresponding alkoxy substituted compound or by reaction with a cuprous halide to yield the corresponding halo substituted compound. 45 Hydroxy substituted compounds can be prepared from the corresponding methoxy compounds by cleavage with, for example, boron tribromide. Alkyl sulphonyl and alkyl sulphinyl substituted aryl derivatives can be prepared by oxidation of the corresponding alkylthio compound by reaction for example with m-chloroperoxybenzoic acid. Similarly when, in formula (I), Z is SO or S02, the compounds can be prepared by oxidation of the analogous thio compound.

50 The pyranones of formula (I) and their pharmaceutically-acceptable salts, have been shown to be useful in the prophylactic and therapeutic treatment of immediate h/persensitivity diseases including asthma and in the alleviation of status asthmaticus. They are also of low toxicity.

This activity has been demonstrated in guinea pigs using either the "guinea-pig chopped lung test" described by Mongar and Schild in the Journal of Physiology (London) 131, 207 (1956) or 55 Brocklehurst in the Journal of Physiology (London) 151 416 (1960) or the "Herxheimer" test described in the Journal of Physiology (London) // 7,251 (1952). For example compounds have exhibited a greater than 15 per cent inhibition of mediator release in the "guinea-pig chopped lung test". In the "Herxheimer" test, which is based on allergic bronchospasm induced in guinea pigs closely resembling an asthmatic attack in man, compounds have exhibited activity at dosages ranging from 25 mg/kg to 60 200 mg/kg.

The compounds may be administered by various routes, although it is a special feature of the

5

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15

20

25

30

35

40

45

50

55

60

4

GB 2 123 814 A 4

compounds that they are effective when administered orally. Thus the compounds may be administered by the oral and rectal routes, topically and parenterally e.g. by injection, being usually employed in the form of a pharmaceutical composition. Such compositions are prepared in a manner well known in the pharmaceutical art and normally comprise at least one active compound or salt of 5 the invention in association with a pharmaceutically-acceptable carrier therefor. In making the 5

compositions of the present invention, the active ingredient will usually be mixed with a carrier, or diluted by a carrier, or enclosed within a carrier which may be in the form of a capsule, sachet, paper or other container. When the carrier serves as a diluent, it may be a solid, semi-solid or liquid material which acts as a vehicle, excipient or medium for the active ingredient. Thus the composition can be in 10 the form of tablets, lozenges, sachets, cachets, elixirs, suspensions, aerosols (as a solid or in a liquid 10

medium), ointments containing for example up to 10% by weight of the active compound, soft and hard gelatin capsules, suppositories, injection suspensions and sterile packaged powders.

Some examples of suitable carriers are lactose, dextrose, sucrose, sorbitol, mannitof, starches, gum acacia, calcium phosphate, alginates, tragacanth, gelatin, syrup, methyl cellulose, methyl- and 15 propyl-hydroxybenzoate, talc, magnesium stearate or mineral oil. The compositions may, as is well 15

known in the art, be formulated so as to provide quick, sustained or delayed release of the active ingredient after administration to the patient.

Preferably the compositions are formulated in a unit dosage form, each dosage containing from 5 to 500 mg, more usually 25 to 200 mg, of the active ingredient. The term "unit dosage form" refers to 20 physically discrete units suitable as unitary dosages for human subjects and animals, each unit 20

containing a predetermined quantity of active material calculated to produce the desired therapeutic effect, in association with the required pharmaceutical carrier.

The active compounds are effective over a wide dosage range and for example dosages per day will normally fall within the range of 0.5 to 300 mg/kg and in the treatment of adult humans, more 25 usually in the range of from 5 to 100 mg/kg. However it will be understood that the amount of the 25

compound actually administered will be determined by a physician, in the light of the relevant circumstances including the condition to be treated, the choice of compound to be administered and the chosen route of administration.

The following Examples illustrate the invention.

30 Example 1 30

4-Dimethylamino-3-phenyl-3-buten-2-one

A stirred mixture of benzyl methyl ketone (26.8 ml) and dimethylformamide dimethyl acetal (30.0 ml) was heated in a distillation apparatus on an oil bath at 95—100°C for 1 -j- hours. Methanol slowly distilled off. The residual volatiles were removed under vacuum and the resulting oil was crystallised 35 from ether-petroleum spirit (40—60°C) to yield the title compound (mp 66°C). 35

Examples 2 to 15

The compounds listed below were prepared by methods similar to that described in Example 1.

40

45

50

COCH,

CHN(CH3)x

Example

Z

R

mp.°C

2

—

4-CI

81

3

—

2-CH30

49—52

4

—

4-CH3

Oil

5

0

H

99—101

6

0

4-CI

113—115

7

0

4-CH3

91—93

8

0

4-CH3O

112—114

9

0

2-CH3O

142

10

s

H

74—76

11

s

4-CI

98—100

12

s

4-CH3O

74—76

13

so.

4-CH3

123—124

14

CO

4-CI

122

15

CO

4-CH3O

126

40

45

50

5

GB 2 123 814 A 5

Example 16

4-Dimethyiamino-3-(4-methoxyphenyl)-3-buten-2-one

A stirred mixture of 1 -(4-methoxyphenyl)-2-propanone (8.2 g) and dimethylformamide diethyl acetal (9.5 ml) was heated on an oil bath at 95—100°C for 30 minutes. Volatile material was removed 5 under vacuum and the residue was crystallised from ether-petroleum spirit (40—60°C) to give the title 5 compound (mp. 56—58°C).

Example 17

Ethyl 4-oxo-5-phenyl-4H-pyran-2-carboxylate

A solution of 4-dimethylamino-3-phenyl-3-buten-2-one (30.3 g) and diethyl oxalate (43.5 ml) in 10 ethanol (75 ml) was added to a stirred solution of sodium ethoxide prepared by dissolving sodium (5.5 10 g) in ethanol (150 ml). The stirred mixture was heated under reflux for 1 hour, cooled to 20—25°C and acidified by addition of 5N hydrochloric acid (150 ml). The mixture was stirred for a further hour, then cooled to 5°C, and diluted with water (300 ml). The solid title product was recrystallised from ethanol-water (mp 110—112°C).

15 Examples 18 to 26 15

Example

Z

R

mp. °C

18

—

2-CH3O

69—71

19

—

4-CH3

101—102

20

0

H

91—93

21

0

4-CI

127—129

22

0

4-CH3

77—79

23

s

4-CI

91—92

24

so.

4-CH3

151—153

25

CO

4-CI

108—109

26

CO

4-CH3O

81—84

Example 27

4-Diethylamino-3-phenyl-3-buten-2-one

30 A solution of diethylstyrylamine (1.75 g) in acetic anhydride (5 ml) was heated under reflux for an 30 hour and then distilled under vacuum (0.02 mm) in a bulb-to-bulb apparatus (oven 150°C). The product was crystallised from ether-petroleum spirit (40—60°C) at low temperature, giving crystals of the title product which melted around room temperature.

This compound was reacted with diethyl oxalate by the method described in Example 17 to give a 35 product, ethyl 4-oxo-5-phenyl-4H-pyran-2-carboxylate, identical with that of Example 17. 35

Example 28

4-Oxo-5-phenyl-4H-pyran-2-carboxylic acid

Ethyl 4-oxo-5-phenyl-4H-pyran-2-carboxylate (4.9 g) was heated with concentrated hydrochloric acid (12 ml) on a steam bath for 1 £ hours. The mixture was cooled and the solid title product was 40 recrystallised from ethyl acetate-dimethylformamide (mp. 225—227°C with decomposition). 40

Example 29

5-(4-ChlorophenyIthio)-4-oxo-4H-pyran-2-carboxylic acid

A solution of ethyl 5-(4-chlorophenylthio)-4-oxo-4H-pyran-2-carboxylate (5.0 g) in dioxan (40 ml) and concentrated hydrochloric acid (20 ml) was heated under reflux for 2 hours then evaporated 45 under vacuum. The solid residue was dried and recrystallised from ethyl acetate-petroleum spirit (60— 45 80°C) to give the title product (mp 165—167°C with decomposition).

6

GB 2 123 814 A 6

Example 30

5-(4-Methylphenylsulphonyl)-4-oxo-4H-pyran-2-carboxylicacid

This compound was prepared by the method described in Example 29 (mp 210°C with decomposition).

Example 31

5-(4-Methoxyphenyl)-4-oxo-4H-pyran-2-carboxylic acid

Ethyl 5-(4-methoxyphenyl)-4-oxo-4H-pyran-2-carboxylate (mp 121—123°C) was prepared by the method described in Example 17 and hydrolysed by the method described in Example 29 to give the title product (mp 232—234°C with decomposition).

10 Example 32

5-(2-Methoxyphenoxy)-4-oxo-4H-pyran-2-carboxylic acid ethyl

Ethyl 5-(2-methoxyphenoxy)-4-oxo-4H-pyran-2-carboxylate (mp 74—76°C) was prepared by the method described in Example 17 and hydrolysed by the method described in Example 29 to give the acid title product (mp 202—203°C).

10

15 Example 33 15

4-Oxo-5-phenylthio-4H-pyran-2-carboxylic acid

Ethyl 4-oxo-5-phenylthio-4H-pyran-2-carboxylate (mp. 79—81 °C) was prepared by the method described in Example 17 and hydrolysed by the method described in Example 29 to give the acid title product (mp. 178—181 °C).

20 Example 34 20

Propyl 5-(4-methoxyphenylthio)-4-oxo-4H-pyran-2-carboxylate

Ethyl 5-(4-methoxyphenylthio)-4-oxo-4H-pyran-2-carboxylate (mp. 90—92°C) was prepared by the method described in Example 17 and hydrolysed to the acid (mp. 190—193°C) by the method described in Example 29. A solution of this acid (5.4 g) in carbon tetrachloride (50 ml), n-propanol (2.9 25 ml) and triethylamine (2.7 ml) was heated under reflux for 7 hours, cooled, washed with dilute 25

hydrochloric acid, then with sodium carbonate solution, dried and evaporated. The residue was crystallised from ethyl acetate-petroleum spirit (60—80°C) to give the title product (mp. 91—93°C).

30

35

Example 35

N-Methyl-4-oxo-5-phenyl-4H-pyran-2-carboxamide

A stirred suspension of 4-oxo-5-phenyl-4H-pyran-2-carboxylic acid (4.3 g) in dry benzene (50 ml) and thionyl chloride (10 ml) was heated under reflux for 12 hours. The clear solution was diluted with petroleum spirit (60—80°C) (50 ml) and cooled to give crystals of the acid chloride (mp. 175°C).

A solution of methylamine (0.338 g) in dry pyridine (4.5 ml) was added to a stirred, cooled suspension of the acid chloride (2.5 g) in dry pyridine (15 ml). The solution was stirred at room temperature for an hour, then cooled and diluted with water (50 ml). The solid title product was dried and recrystallised from chloroform-petroleum spirit (60—80°) (mp. 196—198°C).

30

35

Examples 36 and 37

The compounds listed below were prepared by methods similar to that described in Example 35.

CONHR'

40

45

Example

36

37

Rs CH3 /7-C4Hg ch30

h mp. °C 182—184 157—160

40

Example 38

4-Oxo-5-phenyl-IM-(5-tetrazolyl)-4H-pyran-2-carboxamide

A stirred suspension of 5-aminotetrazole hydrate (0.9 g) in benzene (50 ml) was heated under a Dean and Stark water trap until no further water distilled off. The mixture was cooled and filtered and the solid was immediately dissolved in dry pyridine (20 ml). Solid 4-oxo-5-phenyl-4H-pyran-2-

45

7

GB 2 123 814 A 7

carboxylic acid chloride (2.0 g, prepared as described in Example 35) was added in portions to the cooled, stirred pyridine solution. The mixture was stirred for 2 hours at room temperature, cooled and diluted with water (50 ml). The solid title product was recrystallised from dimethylformamide (mp >300°C).

5 Example 39

N-Butyl-4-oxo-5-phenoxy-4H-pyran-2-carboxamide

Ethyl 4-oxo-5-phenoxy-4H-pyran-2-carboxylate was hydrolysed to the acid (mp. 204—206°C with decomposition), by the method described in Example 29. A stirred suspension of this acid (3.6 g) in dry benzene (40 ml) and thionyl chloride (7.7 ml) was heated under reflux for 12 hours and the resulting 10 clear solution was evaporated under vacuum. The residual oil was twice dissolved in dry benzene and re-evaporated to give crude acid chloride which was reacted with butylamine (1.5 ml) in dry pyridine by the method described in Example 35 to give the title product (mp. 149—151 °C).

Example 40

5-(4-Methoxyphenyl)-4-oxo-4H-pyran-2-carboxamide

1 5 Cold concentrated ammonia solution (30%, 80 ml) was added to a stirred suspension of ethyl 5-(4-methoxyphenyl)-4-oxo-4H-pyran-2-carboxylate (12.4 g) in ethanol (120 ml) at 5—10°C. The mixture was stirred for a further 30 minutes at 0—5°C then the solid title product was washed with water and dried (mp. 262—263°C with decomposition).

Example 41

20 5-(4-Methoxyphenyl)-4-oxo-4H-pyran-2-carbonitrile

A suspension of 5-(4-methoxyphenyl)-4-oxo-4H-pyran-2-carboxamide (8.0 g) and triphenyl phosphine (17.1 g) in carbon tetrachloride (80 ml), methylene chloride (160 ml) and triethylamine (4.55 ml) was stirred for 3\ hours at room temperature. 2N Hydrochloric acid (100 ml) was added to the stirred mixture with cooling, then the solvent layer was washed with water, dried, and evaporated. 25 The solid residue was crystallised from chloroform-petroleum spirit (60—80°C) to give the title product (mp. 165—167°C).

Example 42

4-Oxo-5-phenyl-4H-pyran-2-carbonitrile

Concentrated ammonia solution (40 mi) was added to a stirred suspension of ethyl 4-oxo-5-30 phenyl-4H-pyran-2-carboxylate (4.8 g) in ethanol (40 ml) at 10—15°C. The mixture was then stirred for 30 minutes at 10—15°C. Then the solid product was recrystallised from dimethylformamide-ethanol to give 4-oxo-5-phenyl-4H-pyran-2-carboxamide (mp. 245—248° with decomposition).

A suspension of this amide (3.5 g) and triphenylphosphine (8.54 g) in carbon tetrachloride (10 ml), methylene chloride (20 ml) and triethylamine (2.3 ml) was stirred for 4 hours at room temperature. 35 Ice (60 g) and 2N hydrochloric acid (30 ml) were added, followed by sufficient chloroform to dissolve all the solid material. The solvent layer was washed with water, dried and evaporated, and the residue was crystallised from chloroform-petroleum spirit (60—80°C) and then from ethanol to give the title product (mp. 177—179°C).

Example 43 40 5-Phenyl-2-tetrazol-5-yl-4H-pyran-4-one

A mixture of 4-oxo-5-phenyl-4H-pyran-2-carbonitrile (2.0 g), sodium azide (1.0 g) and ammonium chloride (0.8 g) in dimethylformamide (20 ml) was stirred at room temperature for an hour. Ice (20 g) was added and the clear solution was acidified with 2N hydrochloric acid (20 ml) giving a pale solid which was recrystallised from ethanol to give the title product (mp. 237—238°C with 45 decomposition).

Example 44

5-(4-Methoxyphenyl)-2-tetrazol-5-yl-4H-pyran-4-one

This compound was prepared by the method described in Example 43 (mp. 242—245°C with decomposition).

50 Example 45

Ethyl 5-{2-hydroxyphenyl)-4-oxo-4H-pyran-2-carboxylate

Boron tribromide (3.0 ml) was added dropwise to a stirred solution of ethyl 5-(2-methoxyphenyl)-4-oxo-4H-pyran-2-carboxylate (3.2 g) in methylene chloride (100 ml) at 5—10°C. The mixture was stirred for 2 hours at room temperature, then cooled to 5°C and carefully diluted with water (50 ml). 55 The solid title product was recrystallised from ethanol (mp. 187—189°C).

Example 46

Ethyl 5-(4-hydroxyphenoxy)-4-oxo-4H-pyran-2-carboxylate

Ethyl 5-(4-methoxyphenoxy)-4-oxo-4H-pyran-2-carboxylate (mp. 106—107°C) was prepared by

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15

20

25

30

35

40

45

50

55

8

GB 2 123 814 A 8

the method described in Example 17 and the methoxy group was cleaved by the method described in Example 45 to give the title product (mp. 206—208°C).

Example 47

Ethyl 5-(2-hydroxyphenoxy)-4-oxo-4H-pyran-2-carboxylate

5 This compound was prepared by a method similar to that described in Example 45 (mp. 111— 5 113°C).

Example 48

5-(4-Hydroxyphenoxy)-4-oxo-4H-pyran-2-carboxylic acid

Boron tribromide (8.8 ml) was added dropwise to a stirred solution of ethyl 5-(4-10 methoxyphenoxy)-4-oxo-4H-pyran-2-carboxylate (4.35 g) in methylene chloride (50 ml) causing gentle 10 reflux. The solution was heated under reflux for a further 2 hours, then cooled and carefully diluted with water (25 ml). The solid title product was recrystallised from water (mp 257—258°C with decomposition).

Example 49

15 5-(2-Hydroxyphenoxy)-4-oxo-4H-pyran-2-carboxylic acid 1 5

This compound was prepared by the method described in Example 48 (mp. 193—194°C with decomposition).

Example 50

5-(4-Methoxybenzoyl)-4-oxo-4H-pyran-2-carboxylic acid

20 Treatment of ethyl 5-(4-methoxybenzoyl)-4-oxo-4H-pyran-2-carboxylate with boron tribromide 20 under the conditions described in Example 45 caused preferential cleavage of the ester group to give the title product (mp 185—190°C with decomposition).

Example 51

3-(3,4-Di methoxy phenyl )-4-d imethy la mi no-3-buten-2-o ne

25 This compound was prepared by the method described in Example 1 (mp. 94°C). 25

Example 52

Ethyl 5-(3,4-dimethoxyphenyl)-4-oxo-4H-pyran-2-carboxylate

This compound was prepared by the method described in Example 17 (mp 141—143°C).

Example 53

30 5-(3,4-Dimethoxyphenyl)-4-oxo-4H-pyran-2-carboxylic acid. 30

This compound was prepared by the method described in Example 29 (mp. 210—212°C with decomposition).

Example 54

Ethyl 5-(3,4-dihydroxyphenyl)-4-oxo-4H-pyran-2-carboxylate

35 This compound was p repared by the method described in Example 45 (mp. 206—208°C). 35

Example 55

5-{3,4-Dihydroxyphenyl)-4-oxo-4H-pyran-2-carboxylic acid

This compound was prepared by the method described in Example 29 (mp. 284—285°C with decomposition).

40 Example 56 40

5-(3,4-Dimethoxyphenyl)-IM-methyl-4-oxo-4H-pyran-2-carboxamide

5-(3,4-Dimethoxyphenyl)-4-oxo-4H-pyran-2-carboxylic acid chloride (mp 130°C) was prepared and reacted with methylamine by the method described in Example 35 to give the title product (mp. 213—215°C).

45 Example 57 45

5-(3,4-Dibenzyloxyphenyl)-4-oxo-4H-pyran-2-carboxylic acid

A mixture of ethyl 5-(3,4-dihydroxyphenyl)-4-oxo-4H-pyran-2-carboxylate (3.0 g), anhydrous potassium carbonate (6.0 g) and benzyl bromide (3.0 ml) in dry DMF (30 ml) was stirred at room temperature for 2 hours and then filtered. The filtrate was cooled, acidified with 2N hydrochloric acid 50 (20 ml) and diluted with water (80 ml). The solid product was recrystallised from ethanol to give ethyl 50 5-(3,4-dibenzyloxyphenyl)-4-oxo-4H-pyran-2-carboxylate (mp. 122—125°C).

A stirred solution of this ethyl ester (7.5 g) and dry lithium iodide (15 g) in dry DMF (120 ml)

under nitrogen was heated on an oil bath at 165 to 170°C for 6 hours. The solution was cooled and

9

GB 2 123 814 A 9

acidified with N hydrochloric acid (500 ml) and the solid product was recrystallised from ethanol to give the title product (mp. 206—208°C).

Example 58

Ethyl 5-(4-t-butylbenzoyl)-4-oxo-4H-pyran-2-carboxylate

5 3-(4-t-Butylbenzoyl)-4-dimethylamino-3-buten-2-one was prepared by the method described in Example 1 6 and used without purification to prepare the title compound (mp. 82—85°C) by the method described in Example 17.

Example 59

5-(4-t-Butylbenzoyl)-4-oxo-4H-pyran-2-carboxylic acid

10 This compound was prepared by cleavage of the ethyl ester as described in Example 48, (mp. 133—145°C).

Example 60

3-(4-t-Butylphenoxy)-4-dimethylamino-3-buten-2-one

This compound was prepared by the method described in Example 1 (mp. 98°C).

15 Example 61

5-(4-t-Butylphenoxy)-4-oxo-4H-pyran-2-carboxylic acid

Ethyl 5-(4-t-butylphenoxy)-4-oxo-4H-pyran-2-carboxylate (mp. 108—110°C), was prepared by the method described in Example 17 and hydrolysed as described in Example 29 to give the title product (mp. 190—193°C with decomposition).

20 Example 62

3-[4{Cyclohexyl)phenoxy]-4-dimethylamino-3-buten-2-one

Freshly distilled chloracetone (31 ml) was added to a solution of sodium iodide (1.0 g) in dry acetone (50 ml). The mixture was allowed to stand for 1 hour at room temperature and then added over 1 hour to a stirred, refluxing mixture of 4-(cyclohexyl)phenol (52.8 g) and anhydrous potassium 25 carbonate (52 g) in dry acetone (100 ml). The stirred mixture was heated under reflux for a further 5 hours, filtered and evaporated to a brown oil which crystallised from ether-petroleum spirit (40— 60°C) to give [1-4-(cyclohexyl)phenoxy]-2-propanone (mp 58°C).

The title compound was prepared from this ketone by the method described in Example 1 (mp. 137°C).

30 Example 63

5-[4-(Cyclohexyl)phenoxy]-4-oxo-4H-pyran-2-carboxylic acid

Ethyl 5-[4-(cyclohexyl)phenoxy]-4-oxo-4H-pyran-2-carboxylate (mp. 159°C) was prepared by the method described in Example 17 and hydrolysed as described in Example 29 to give the title product (mp. 187—190°C).

35 Example 64

5-(4-Butylphenyl)-4-oxo-4H-pyran-2-carboxylic acid

A stirred solution of 4-butylbenzaldehyde (13.5 g), nitroethane (9.0 ml) and butylamine (1.6 ml) in ethanol (20 ml) was heated under reflux for 6 hours and evaporated. The residue was distilled under vacuum to give 1-(4-butylphenyl)-2-nitropropene (bp. 124—125°C/0.1 5 mm).

40 Concentrated hydrochloric acid (6.5 ml) was added in small portions over 6 hours to a stirred mixture of this nitropropene (7.6 g), iron powder (13.6 g) and ferric chloride (0.1 g) in water (50 ml) whilst heating under reflux. The mixture was steam-distilled and the distillate extracted with ether. The extract was dried and evaporated and the residue was distilled under vacuum to give 1 -(4-butylphenyl)-2-propanone.

45 This ketone (4.6 g) was reacted with dimethylformamide dimethyl acetal (4.0 ml) as described in Example 1 to give 3-(4-butylphenyl)-4-dimethylamino-3-buten-2-one which was used without purification to prepare ethyl 5-(4-butylphenyl)-4-oxo~4H-pyran-2-carboxyiate (mp. 65°C), by the method described in Example 17.

This ester was hydrolysed by the method described in Example 29 to give the title product (mp. 50 193—195°C).

Example 65

Ethyl 3-bromo-4-oxo-5-phenyl-4H-pyran-2-carboxylate

A suspension of sodium ethoxide was prepared by addition of ethanol (1.6 ml) to a stirred suspension of sodium hydride (1.3 g 50% dispersion), washed with petroleum spirit (40—60°C) in 55 ether (50 ml) under nitrogen. A solution of 4-dimethylamino-3-phenyl-3-buten-2-one (4.8 g) and diethyl oxalate (5.2 ml) in ether (50 ml) was added to the stirred sodium ethoxide suspension at 5 to 10°C and the resulting clear solution was stirred for 2 hours at room temperature, then cooled and

5

10

15

20

25

30

35

40

45

50

55

10

GB 2 123 814 A 10

treated with glacial acetic acid (2.5 ml) and water (50 ml). Ethyl acetate was added to dissolve the solid which formed and the solvent layer was washed with water, dried, and evaporated. The solid residue was recrystallised from ethyl acetate-petroleum spirit (60—80°C) to give ethyl 6-dimethylamino-2,4-dioxo-5-phenyl-5-hexenoate (mp. 110°C).

5 A solution of bromine (0.73 ml) in chloroform (10 ml) was added dropwise to a stirred solution of 5 this hexenoate (4.1 g) in chloroform (50 ml) at —20°C to —25°C. The solution was stirred for 1y hours at room temperature, washed with water and evaporated.

The residual solid was crystallised from ethanol-water to give the title product (mp. 134°C).

The following Examples illustrate pharmaceutical formulations containing compounds of formula 10 (I). The active ingredient used was ethyl 4-oxo-5-phenyl-4H-pyran-2-carboxylate. However this 10

compound can be replaced by other active solid compounds of the invention.

Example 66

Tablets each containing 50 mg of active ingredient were made up as follows:

Active ingredient 50 mg

15 Starch 200 mg 15

Lactose 200 mg

Polyvinylpyrrolidone 20 mg

(as 10% solution in water)

Sodium starch glycolate 20 mg 20 Magnesium stearate 10mg 20

Total 500 mg

The starch, lactose and active ingredient were passed through a sieve and thoroughly mixed. The solution of polyvinylpyrrolidone was mixed with the resultant mixture and the combination passed through a No. 12 mesh B.S. sieve. The granules so produced were dried at approximately 55°C and 25 passed through a No. 16 mesh B.S. sieve. The magnesium stearate and sodium starch glycolate, 25

previously passed through a No. 60 mesh B.S. sieve, were then added to the granules which, after mixing, were compressed on a tablet machine to yield tablets each weighing 500 mg.

Example 67

Capsules each containing 50 mg of medicament were made as follows:

30 Active ingredient 50 mg 30

Starch 42 mg

Lactose 45 mg Magnesium stearate 3 mg

Total 140mg

35 The lactose, starch, magnesium stearate and active ingredient were passed through a No. 44 35

mesh B.S. sieve and filled into hard gelatin capsules in 140 mg quantities.

Example 68

Suppositories each containing 25 mg of active ingredient were made as follows:

Active ingredient 50 mg

40 Saturated fatty acid glycerides to 2,000 mg 40

The active ingredient was passed through a No. 60 mesh B.S. sieve and suspended in the saturated fatty acid glycerides previously melted using the minimum heat necessary. The mixture was then poured into a suppository mould of nominal 2 g capacity and allowed to cool.

Claims

Claims

45 1. A compound of the formula 45

(R8)2N R3 o

\ I X c=c— c

/ \

R2 CH,R4

11

GB 2 123 814 A

11

in which R2 is hydrogen or C,_6 alkyl, R3 is a group of the formula R6—(Z)m— where m is 0 or 1, Z is 0, S, SO, S02 or CO, and R6 is phenyl optionally substituted by one or more groups selected from halogen, C,_4 alkyl, C3_6 cycloalkyl, Cn_4 alkoxy, benzyloxy, hydroxy, nitro, C,_4 alkylthio, C,_4 alkylsulphinyl, C1-4 alkylsulphonyl, amino and NHR7 where R7 is C2_6 acyl; R4 is hydrogen or C^g alkyl; and each R8 is C,^ 5 alkyl or (R8)2N is a saturated heterocyclic ring. 5
2. A compound according to claim 1, in which each R8 is C,_6 alkyl.
3. A compound according to either of claims 1 and 2 in which both R2 and R4 are hydrogen.
4. A compound according to any of the preceding claims in which R6 is phenyl optionally substituted by 1 to 3 substituents selected from halogen, C^ alkyl, methoxy, benzyloxy and hydroxy.

10
5. A compound according to any of the preceding claims in which R3 is of the formula R6—(Z)m— 10 where m is 0 or 1 and Z is 0 or CO.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1984. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.