GB2062626A

GB2062626A - 3-imidazol-2-yl-3 phenyl propanamines and prop-2-enamines

Info

Publication number: GB2062626A
Application number: GB8032001A
Authority: GB
Original assignee: Glaxo Group Ltd
Current assignee: Glaxo Group Ltd
Priority date: 1979-10-03
Filing date: 1980-10-03
Publication date: 1981-05-28
Also published as: SE8006953L; DK420480A; FI803127L; AU6294580A; ES495589A0; BE885507A; FR2466461A1; ES8301221A1; NL8005491A; NZ195144A; IT8049815A0; JPS5690063A; ES8205204A1; FR2466461B1; DE3037313A1; ES505556A0; IT1144007B; ZA806146B; US4324792A; ES8203855A1

Description

1

GB 2 062 626 A 1

SPECIFICATION Heterocyclic Compounds

This invention relates to heterocyclic compounds having action on histamine receptors, to processes for their production and to pharmaceutical compositions containing them.

5 Classical anti-histamines (H^antagonists) are used for the treatment of conditions in which 5

histamine is a mediator, for example in the treatment of skin afflictions, hay fever and asthma.

Compounds of this type suffer from the disadvantage that they produce a significant level of side-effects in man. These often result from the interaction of the anti-histamine with the central nervous system (CNS) of the patient, for example to produce mild to moderate sedation. Other side effects of 10 classical anti-histamines are due to their anticholinergic activity, for example dry mouth. 10

Certain heterocyclic compounds have now been found which exhibit H,-antagonist activity with only weak anti-cholinergic activity. Some of the compounds according to the invention may have advantages over existing anti-histamines that act on Hrreceptors in that they are much less lipophilic.

This should inhibit penetration of the CNS so that these compounds may have fewer side-effects, 15 especially the sedation usually associated with this type of drug. The compounds according to the 15 invention are of value in the treatment of conditions where anti-histamines that act on Hrreceptors are indicated, for example skin afflictions, hay fever and asthma.

The present invention provides compounds of the general formula (I)

(i) '

nr2r3

20 and physiologically acceptable salts and bioprecursors thereof in which 20

; X—Y— represents either; CH—CH2— or > C=CH—; R1 represents hydrogen, halogen, C,_4 alkoxy, hydroxy, alkyl, R4CH(OH)—, cyano or R5 CONH—; R2 and R3, which may be the same or different, each represents an alkyl group or alkenyl group or R2 and R3 may, together with the nitrogen atom to which they are attached, form a saturated heterocyclic ring containing 25 from 5 to 7 members which may optionally contain an oxygen atom; R4 represents hydrogen 25

or alkyl; and R5 represents hydrogen, alkyl or C1-4 alkoxy.

The term "alkyl" as a group or part of a group unless otherwise stated, means that the group is straight or branched and has preferably 1 to 4 carbon atoms, e.g. methyl or ethyl. The term "alkenyl"

means that the group is straight or branched and has preferably from 3 to 6 carbon atoms. The term 30 halogen preferably means chlorine or bromine. 30

The invention includes all optical and geometrical isomers of the compounds of general formula (I) and mixtures thereof.

Geometrical isomers exist where > X—Y— represents > C=CH— represented in conventional manner as follows:—

"XX

35 m m h

35

h ch2

r2r3n nr2r3

E — isomer j. — isomer

The invention includes the compounds of general formula (I) in the form of physiologically acceptable salts with inorganic and organic acids. Particularly useful salts include hydrochlorides,

sulphates and maleates.

Compounds of the general formula (I), optionally in salt form have been shown to exhibit Hr 40 antagonist activity in standard pharmacological tests. For example they inhibit the contraction of the 49 guinea pig isolated ileum preparation induced by histamine. Certain representative compounds have also been shown to inhibit the action of histamine in the conscious guinea pig using the test described by Loew, Kaiser and Moore, J. Pharmac exp. Ther, 83, 120 (1945).

2

GB 2 062 626 A 2

The compounds according to the invention, optionally in the form of a salt, may be formulated for administration in any convenient way and the invention includes within its scope pharmaceutical compositions containing at least one compound according to the invention adapted for use in human or veterinary medicine. Such compositions may be formulated in a conventional manner using one or 5 more pharmaceutical^ acceptable carriers or excipients. Formulations for administration of the 5

compounds according to the invention include forms suitable for oral administration, suppositories,

injections and forms suitable for administration by inhalation. Oral administration is preferred. For oral administration the pharmaceutical composition may take the form of, for example, tablets, capsules,

powders, solutions, syrups or suspensions prepared by conventional means with acceptable excipients. 10 For internal administration, the dosage at which the active ingredient is administered may vary within a 10 wide range, depending on age, weight and condition of the patient. A suitable dose is in the range 4 to 200 mg, taken 1 to 4 times daily.

Preferred meanings for the group R1 are a hydrogen atom, a halogen atom or a methyl, methoxy, hydroxymethyl or 1 -hydroxyethyl group and for R2 and R3 are both methyl groups or together with the 15 nitrogen atom to which they are attached form a pyrrolidine ring. 15

When >X—Y— represents >C=CH— in the general formula (I), the preferred compounds are those in which R1 represents a hydrogen atom or a methyl group and R2 and R3 together with the nitrogen atom to which they are attached from a pyrrolidine ring.

Also, when >X—Y— represents >C=CH—then the preferred compounds are the E-isomers. 20 Preferably the group >X—Y—represents the group >CH—CH2—. 20

Those compounds of general formula (I) in which >X—Y— represents >CH—CH2—, R1 is hydrogen, methoxy, hydroxymethyl or 1-hydroxyethyl and R2 and R3 are both methyl have the additional advantage that they, as determined by the method of Mirrlees et al, J. Med. Chem., 19, 651 (1976), have a low lipophilicity compared with known H^antagonists which should reduce or minimise 25 CNS side effects. A particularly preferred compound according to the invention is that in which R1 is 25 hydrogen, R2 and R3 are both methyl and >X—Y— is >CH—CH2.

Compounds of general formula (I) in which >X—Y— represents >CH—CH2— may be prepared from a compound of general formula (II):

nh

'ch nhch2ch(or6)2

ch2

I 23 <n)

ch2nr2r3

30 wherein R6 represents a C,—C4 alkyl group (preferably methyl) or the two R6 groups may be linked 30

together to form a cyclic acetal by treatment with a dilute mineral acid, for example hydrochloric acid, preferably with heating for example to 80°C to 100°C.

A compound of general formula (II) may be prepared by reaction of an aminoacetaldehyde acetal with an imino ether of general formula (III):

" ll c^NH

*-CH^ ^OR7

I

35 CH2

I (in) 35

ch2

I

nr2r3

wherein R7 is a C,—C6 alkyl group.

The imino ether of general formula (III) in the form of its hydrochloride salt may be prepared by reaction of a nitrile of general formula (IV)

,cn ch CH,

(E)

ch2

nr r

2o3

3

GB 2 062 626 A 3

with anhydrous hydrogen chloride and an alkanol, e.g. methanol or ethanol, optionally in the presence of a solvent such as dichloromethane. The imino ether hydrochloride salt can be converted into the free base by reaction with a suitable quantity of an alkoxide, for example sodium alkoxide. The imino ether free base is then reacted with the aminoacetaldehyde acetal generally without isolation to give the compound of general formula (II).

Compounds of formula IV can be prepared by reacting a phenylacetonitrile (V)

R!

.CN (V)

~CH2

with a compound (VI)

R2R3N(CH2)2CI (VI)

10 in the presence of a base, for example sodium hydride in a solvent, such as dimethyl formamide, at an 10 elevated temperature, e.g. 50°C.

An alternative method of preparing compounds of general formula (I) wherein >X—Y—

represents >CH—CH2— comprises reacting an amidine of general formula (VII)

d1

c^NH

"ch' nh2 ch2

(sn;

ch2

nr2r3

15 with glycollic aldehyde preferably with heating in a solvent such as an alkanol. The amidine (VII) may 15 be prepared from an imino ether (III) by treatment with ammonia in a suitable solvent e.g. methanol. In a modification of this process compounds of formula (I) may be prepared by treating the imino ether (III) with ammonia and glycollic aldehyde in a solvent such as methanol. Preferably the reaction is carried out at elevated temperatures, e.g. 50—100°C in an autoclave.

20 Compounds of general formula (I) in which >X—Y— represents >C=CH— may be prepared from 20 a 2-benzoylimidazole of general formula (VIII).

"XX

o r8

(3zm)

in which R8 is a hydrogen atom or a suitable protecting group, such as ethoxymethyl or benzyl, by reaction with a triphenylphosphonium bromide (IX)

25 R2R3NCH2CH2P®Ph3B®r; (IX) 25

in the presence of a base to give the compound of formula (X)

q1

ch ch2

R8

(x)

nr2r3

The reaction may be carried out in a suitable solvent such as tetrahydrofuran in the presence of the base, for example, /j-butyl lithium, preferably at a temperature of between —30°C to +20°C. 30 The protecting group R8 can be removed in conventional manner to give a compound of formula 30

(I) in which >X—Y— is >CH=CH—. For example, when the protecting group is ethoxymethyl it can be

removed by treatment with a mineral acid such as hydrochloric acid. The product represented by formula (X) is a mixture of E and Z isomers which are separable, for example, by preparative layer chromatography.

The ketones (VIII) where R8 is hydrogen are either known compoundsor may be prepared by 5 acylation of imidazoles by the method of Bastiaansen and Godefroi, Synthesis, (1978) page 675. The ketones (VIII) where R8 is for example an ethoxymethyl or benzyl group may also be known compounds or may be prepared from 1-substituted imidazoles by the general procedure of Regel and Buchel, (Ann. 159(1977) 145).

Triphenylphosphonium bromides (IX) may be prepared by fusing the hydrobromide of 10 triphenylphosphine with the appropriate dialkylamino ethanol. Alternatively these compounds can be prepared by heating 2-phenoxyethyltriphenylphosphonium bromide with the appropriate secondary amine in an inert solvent such as dimethylsulphoxide.

Compounds of general formula (I) in which >X—Y— represents >CH—CH2— can be also prepared by reducing either isomer of compounds of general formula (I) in which >X—Y— represents 15 >C=CH—. Reduction is effected on either the E- or Z-isomer or on a mixture of the isomers. Reduction can be effected for example by hydrogenation in the presence of a catalyst for example palladium or by treatment with sodium in liquid ammonia, optionally in a solvent such as toluene. Where R8 in the compound of formula (X) is a benzyl group reduction with sodium and liquid ammonia can be carried out directly on the compound of formula (X). The reduction also removes the protecting group and 20 yields the compound of formula (I) in which >X—Y— represents >CH—CH2—.

Compounds of general formula (I) in which R1 represents a hydroxyalkyl group can be prepared from compounds of formula (I) in which R1 represents a group convertable to a hydroxyalkyl group by reduction. Thus for example compounds of general formula (I) in which R1 represents hydroxymethyl may be prepared by reduction of the corresponding compound of formula (I) in which R1 is an 25 alkoxycarbonyl group. Reduction may be effected with a suitable metal hydride such as lithium aluminium hydride in a solvent such as tetrahydrofuran or dioxan.

Compounds of general formula (I) in which R1 represents the group R4CH(0H)—may be prepared by reduction of the corresponding compound of formula (I) wherein R1 represents R"CO for example with a metal hydride such as sodium borohydride in a solvent such as ethanol or with hydrogen in the 30 presence of suitable metal catalyst such as platinum. In the latter case if >X—Y— in the alkanoyl starting compound represents >C=CH—this will also be reduced to >CH—CH2 in the resulting compound of general formula (I).

Compounds of formula (I) in which R1 represents the group R5CONH— may be prepared from the corresponding compound of formula (I) in which R1 represents a primary amino group. For example, 35 compounds in which R5 is hydrogen or an alkyl group may be prepared by standard acylation procedures such as reaction with the acid R5COzH or an activated derivative thereof such as the acid chloride or anhydride.

Compounds of formula (I) in which R1 represents a cyano group may be prepared from the corresponding compound of formula (I) in which R1 represents a primary amino group by forming the 40 diazonium salt and reacting this with sodium cyanide.

Compounds of formula (I) in which R1 is the group —NHZ may be prepared from compounds of formula (I) in which R1 is an alkoxycarbonyl group by reaction with hydrazine followed by reaction of the resulting hydrazide with sodium nitrite and hydrochloric acid to give the isocyanate (l;R1=NCO). This isocyanate is heated with benzylalcohol and the resulting urethane (hR1,—NHC02CH2Ph) is 45 hydrogenated in the presence of a metal catalyst such as palladium to give the desired amine (l;R\— • NH2).

Compounds of the general formula (I) where R1 represents the group R4C0 or an alkoxycarbonyl group may be prepared by the routes described above for preparing the compounds of the invention. For example, compounds where R1 represents R4C0 or an alkoxycarbonyl group and the group 50 >X—Y— represents >CH—CH2— may be prepared from the compound of formula (II) wherein R1 represents R4C0 or an alkoxycarbonyl group.

Where the product of any of the above processes is a free base and a salt is required, the salt may be formed in a conventional manner. Thus for example a solution of free base in a suitable solvent, e.g. acetone, may be treated with the appropriate acid.

55 The invention is illustrated by the following Examples:

Example 1

(a) 4-[3-(N,N-Dimethylamino)-1-(imidazol-2-yI)propyl]benzenemethanol

(i) 4-[3-(N,l\l-DimethyIamino)-1-cyanopropyl]benzoic Acid, Methyl Ester

A solution of 4-cyanomethylbenzoic acid, methyl ester (28.8 g) in dry dimethylformamide (DMF) 60 (100 ml) was added dropwise to a stirred suspension of sodium hydride (80% dispersion in oil, 5.4 g) in

DMF (50 ml) under nitrogen. The mixture was stirred at 50° for 1 h., then a solution of dimethylaminoethyl chloride (21.3 g) in DMF (50 ml) was added and stirring was continued at 50° for

18 h.

5

10

15

20

25

30

35

40

45

50

55

60

5

GB 2 062 626 A 5

The mixture was poured onto ice (500 g), acidified and extracted with ethyl acetate (3x200 ml) and the extracts were discarded. The aqueous phase was basified and again extracted with ethyl acetate (3x300 ml). The extracts were dried (Na2S04) and removal of the solvent gave the title compound as a yellow oil, b.p. 146—150°/0.3 mm (18.8 g).

5 (a) 4-acetyl-a-(N,N-dimethylaminoethyl)-benzeneacetonitrile (3.23 g) was prepared in a similar 5 manner from 4-acetylbenzeneacetonitrile (6.71 g) using tetrahydrofuran in place of DMF as the solvent.

(ii) 4-[3-(N,N-Dimethylamino)-1-(imidazol-2-yl)propyl]-benzoic Acid, Methyl Ester.

Dry hydrogen chloride was passed into an ice-cooled solution of 4-[3-(N,N-dimethylamino)-1-10 cyanopropyl]benzoic acid, methyl ester (5.0 g) and ethanol (5 ml) in dry dichloromethane (100 ml) for 3 10 h. and the mixture was stirred at room temperature for 18 h. The solution was evaporated to dryness and the residue taken up into dry methanol (50 ml) and treated with sodium methoxide [from sodium 0.48 g, and methanol (20 ml)] and aminoacetaldehyde dimethylacetal (2.2 ml). The mixture was stirred at room temperature for 1 day, then filtered and the filtrate concentrated to a gum. The gum was 15 dissolved in 2N hydrochloric acid (20 ml), and heated on a steam bath for 2 h. The solution was then 15 basified and extracted with ethyl acetate (3x50 ml). The extracts were dried (Na2S04) and concentrated to a white solid which crystallised from ether/petroleum ether to give the title compound, m.p. 102—104° (2.3 g). The following compounds were prepared in a similar manner:

(a) 3-(4-chlorophenyl)-3-(imidazol-2-yl)-N,N-dimethyl-1-propanamine m.p. 129—132° (from

20 ether), t (CDCI3) 2.7—3.1 (4H, m, aromatic, 3.1 (2H, s, imidazole), 5.87 (1H, t, —CH—), 7.5—8.2 20 (10H, s m, CH2CH2N(CH3)2), from 4-chloro-a:-(N,N-dimethylaminoethyl)-benzeneacetonitrile.

(b) N,N-Dimethyl-3-(imidazol-2-yl)-3-phenyl-1-propanamine, m.p. 137—138° (from ethyl acetate-cyclohexane) (1.64 g), t(CDCI3) 2.83 (5H, m, aromatic), 3.13 (2H, s, imidazole), 5.81 (1H, m, —CH—), 7.6—8.0 (8H, m, CH2—-Ctf2N(CH3)2), 7.82 (6H, s, N(CW3)2) from a-(N,N-

25 dimethylaminoethyl)benzeneacetonitrile (6.0 g). 25

(c) 1-[4-[3-(N,N-Dimethylamino)-1-(imidazol-2-yl)-propyl]phenyl]ethanone m.p. 160—161°

(from ethyl acetate-cyclohexane) (1.65 g) from 4-acetyl-a-(N,N-dimethylamino)benzeneacetonitrile (3.23 g).

(iii) 4-[3-(N,N-Dimethylamino)-1-(imidazol-2-yl)propyI]benzenemethanol

30 Lithium aluminium hydride (0.4 g) was added slowly to a stirred solution of 4-[3-(N,N- 30

dimethylamino)-1-(imidazol-2-yl)propyl]benzoic acid, methyl ester (1.0 g) in dry tetrahydrofuran (40 ml) under nitrogen. After stirring for 2 hr., water (3 ml) was added, and the granular suspension was filtered off. The filtrate was evaporated to dryness to give a colourless gum which was dissolved in methanol (5 ml) and treated with a solution of maleic acid (0.4 g) in methanol (5 ml). Solvent was 35 removed and the residual gum was triturated with dry ether to give the maleate salt hemihydrate of the 35 title compound as a glassy, hygroscopic solid, m.p. 65—66° (1.1 g); r (D20) 2.4—2.65 (4H, m,

aromatic), 2.70 (2H, s, imidazole), 5.33, 5.50 (3H, s, HOCHZ,—CH—), 6.7—7.6 (10H, m,

CH£H2N(CH3)2), 7.08 (6H, s, N(CH3)2).

Example 2

40 N-[4-[1 -(lmidazol-2-yl)-3-(l\l,N-dimethylamino)propyl]phenyl]formamide 40

(i) 4-[3-(N,N-Dimethylamino)-1-(imidazol-2-yl)propyl]benzoic acid hydrazide

A solution of 4-[3-(N,N-dimethylamino)-1-(imidazol~2-yl)propyl]benzoic acid, methyl ester (3.0 g) and hydrazine hydrate (12.5 ml) in ethanol (50 ml) was boiled under reflux for 1 day. Removal of the solvent gave a white solid which was recrystallized from isopropanol-ether to give the title compound, 45 m.p. 168—170° (2.46 g). 45

(ii) 3-(4-Aminophenyl)-N,IM-dimethyl-3-(imidazol-2-yl)propanamine

A solution of sodium nitrite (0.5 g) in water (5 ml) was added dropwise to a stirred solution of 4-[3-(N,N-dimethylamino)-1-(imidazol-2-yl)propyl]benzoic acid hydrazide (2.0 g) in 2N hydrochloric acid (10.5 ml) and water (50 ml) at 0 to 5°C. After 30 min. the solution was basified by adding 2N sodium 50 carbonate (15 ml) and then extracted with ether (3x50 ml). The extracts were dried (Na2S04) and 50 concentrated to an off white solid (1.7 g). This solid was dissolved in toluene (40 ml) and benzyl alcohol (1.5 ml) and heated on a steam bath for 2 h. Solvent was removed and the residue taken up in ethanol (20 ml) and hydrogenated at atmospheric pressure over 10% palladium oxide on charcoal (0.5 g) for 3 h. The catalyst was filtered off and the filtrate treated with a solution of maleic acid (1.8 g) in 55 ethanol (10 ml). Removal of the solvent and trituration of the residue with dry ether afforded a white 55 solid. Recrystallisation from ethanoi-ether gave the trimaleate salt of the title compound, m.p. 132— 133° (2.6 g).

(iii) N-[4-[1-(lmidazol-2-yl)-3-(N,N-dimethylamino)propyl]phenyl]formamide

A mixture of 3-(4-aminophenyl)-N,N-dimethyl-3-(imidazol-2-yl)propanamine (0.8 g), formic acid

6

GB 2 062 626 A 6

(2 ml) and toluene (50 ml) was boiled under reflux for 2 days in a Dean and Stark apparatus. Solvent was removed and the residue partitioned between 2N sodium carbonate (25 ml) and ethyl acetate (3x50 ml). The extracts were dried (Na2S04) and concentrated to a white solid. Recrystallisation from ethyl acetate gave the title compound, m.p. 142—144°, (0.46 g). v max (CHBr3) 3445,3420 3390 5 (NH), 1690 (CO), 1500,2780 and 2820 cm"1. ' 5

Example 3

4-[3-{N,N-Dimethylamino)-1 -(imidazol-2-yl)propyl]benzonitrile

A solution of sodium nitrite (0.3 g) in water (5 ml) was added dropwise to a stirred solution of 3-(4-aminophenyl)-N,N-dimethyl-3-(imidazo!-2-yl)propanamine (1.0 g) in 2N hydrochloric acid (6 ml) 10 and water (6 ml), keeping the temperature at 3—5°. After stirring for 30 min. the dark red solution was 10 adjusted to pH 7—8 and treated with sodium cyanide (0.2 g) and cuprous cyanide (0.4 g) and heated on a steam bath for 3 h. The mixture was then adjusted to pH 11—12 and extracted with ethyl acetate (3x30 ml). The extracts were dried (Na2S04) and concentrated to give the title compound as a gum (0.33 g) which was taken up into methanol (5 ml) and treated with a solution of maleic acid (0.15 g) in 15 methanol (5 ml). Removal of the solvent and trituration of the residue with ether gave the dimaleate 15

salt of the title compound as an off white solid that crystallised from ethanol-ether with m.p. 147— 148°;t(D20) 2.06 to 2.35 (2H, m, aromatic), 2.48 (2H, br.s, imidazole), 5.23 (1H, m,—bH—), 6.5— 7.5 (4H, m, CH2CH2N(CH3)2), 7.03 (6H, s, N (CH3)2).

Example 4

20 1 -[4-[3-(N,N-Dimethylamino)-1 -(imidazol-2-yl)propyl]phenyl]ethanol 20

A mixture of 1-[4-[(3-N,N-dimethylamino)-1-(imidazol-2-yl)propyl]phenyl]ethanone (1 g) and sodium borohydride (0.1 g) in ethanol (10 ml) and water (1 ml) was stirred at room temperature for 75 h. Additional quantities (0.1 gx2) of sodium borohydride were added after 2.5 h and 68 h. The mixture was concentrated and the residue partititioned between 2N sodium carbonate (25 ml) and ethyl 25 acetate (3x25 ml). The extracts were dried (Na2S04) and evaporated to a yellow gum (0.86 g) which 25 was distilled to give the title compound as a colourless glass b.p. 250°/0.1 mm Hg. (0.65 g) wmax (CHBr3) 3585 (OH), 3440 (NH), 2770, 2820 (CH2N(CH3)2).

Example 5

N,N-Dimethyl-3-(4-methoxyphenyl)-3-(imidazol-2-yl)propanamine

30 (i) 4-methoxyphenyl-2-(1-phenylmethyl)imidazolyl-methanone 30

Anisoyl chloride (4.3 ml) was added slowly to a stirred solution of 1-benzylimidazole (5.0 g) in dry acetonitrile (50 ml) keeping the temperature at 25—30°. After stirring for 1 h triethylamine (4.4 ml) was added dropwise and the mixture stirred for 18 h then filtered. The filtrate was concentrated to dryness, and the residue taken up into ether (100 ml) and washed with acetic acid (25%, 3x50 mi), 35 and 2N sodium carbonate (3x50 ml), then concentrated until the title compound crystallised as a 35

white solid, m.p. 108—110° (3.1 g).

ii) (E) and (Z)-IM,N-Dimethyl-3-(4-methoxyphenyl)-3-[(1-phenylmethyl)imidazol-2-yl]-2-propen-1-amine n-Butyl lithium (0.93M, 11 ml) was added dropwise to a stirred suspension of 40 dimethylaminoethyl triphenylphosphonium bromide (4.1 g) in dry tetrahydrofuran (50 ml) at—30° 40

under nitrogen. The orange solution was allowed to warm to room temperature and a solution of 4-methoxy-phenyl-2-(1-phenylmethyl)imidazolylmethanone (2.9 g) in tetrahydrofuran (20 ml) was added. After stirring for 4 h. hydrochloric acid (2N, 20 ml) was added and the solvent removed in vacuo. The residual aqueous solution was washed with ethyl acetate (3x50 ml) adjusted to pH9 and 45 then extracted with ethyl acetate (3 x 50 ml). This solution was extracted with dilute acetic acid (3 x 50 ml) 45 which was then basified (2N Na2C03) and back extracted with ethyl acetate (3x50 ml). The extracts were dried and concentrated and the residue was distilled to give the propenamines as a yellow oil b.p. 250°/0.05 mm Hg (1.36 g) which was used in the next stage.

iii) N,N-Dimethyl-3-(4-methoxyphenyl)-3-(imidazol-2-yl)propanamine

50 A solution of (E) and (Z)-N,N-dimethyl-3-(4-methoxyphenyl)-3-[(1-phenylmethyl)imidazol-2-yl]- 50 2-propen-1-amine (1.0 g) in dry toluene (20 ml) was added to liquid ammonia (20 ml) with stirring at —78°. Sodium was added until the mixture was deep blue (ca. 0.23 g required). After stirring at —78°

for 2 h ammonium chloride (1 g) was added, the mixture allowed to warm to room temperature and the residue partitioned between 2N sodium carbonate (50 ml) and ethyl acetate (3x50 ml). The organic 55 solution was dried (NazS04) and concentrated to give the title compound as a white solid (0.67 g) 55

which crystallised from ether with m.p. 131—133°, <umax(CHBr3) 3440 (NH), 2770,2820 (Me2NCH2—).

7

GB 2 062 626 A 7

Example 6

1-(lmidazol-2-yl)-1-(4-methylphenyl)-3-(1-pyrrolidinyl)propane

(i) (1-Ethoxymethylimidazol-2-yl)-4-methylphenylmethanone

To a stirred suspension of 1-ethoxymethylimidazole (19.5 g) in dry acetonitrile (300 ml) was 5 addedp-toluyl chloride (23.91 g) and triethylamine (15.65 g), keeping the temperature below 35°. The 5 suspension was stirred at room temperature for four days, then the precipitated triethylamine hydrochloride was filtered off and the filtrate concentrated in vacuo. The residue was taken up in ethyl acetate (150 ml) and the organic layer was washed with 2N sodium carbonate (2x70 ml, 1 x50 ml), saturated brine (50 ml) and dried (MgS04).

10 Removal of the solvent gave a dark red oil (36 g) which was diluted with ethyl acetate- 10

cyclohexane (15 ml, 1:1) and absorbed onto a column of silica gel (Merck Kieselgel 7736N, 750 g).

Elution with ethyl acetate-cyclohexane (1:1) under pressure (60 mm Hg.) afforded an oil contaminated with p-toluic acid. This material was distilled at 0.1 mm. Hg. and the distillate diluted with petroleum ether (4 ml) and filtered to remove the acid. The filtrate was concentrated and distilled to give the title 15 compound as a yellow oil b.p. 180°/0.06 mm (6.89 g). 15

By the method of Example 6 (i) (1-ethoxymethylimidazol-2-yl)-phenylmethanone was prepared from 1 -ethoxymethylimidazole and benzoyl chloride.

(ii) (E) and (Z)-1-[-Ethoxymethylimidazol-2-yl]-1-4-methylphenyl)-3-(1-pyrrolidyl)prop-1-ene

A solution of n-butyl lithium in hexane (1.6M, 7.7 ml) was added dropwise under nitrogen with 20 stirring to a suspension of 2-(1-pyrrolidyl)ethyltriphenylphosphonium bromide (5.41 g) in dry THF (75 20 ml) keeping the temperature at —10° to —5°. The addition was complete after 5 min. The mixture was then stirred at 0° for 20 min. then cooled to —5° and treated with a solution of (1-ethoxymethylimidazol-2-yl)-4-methylphenylmethanone (3.0 g) in dry THF (30 ml). The mixture was stirred at room temperature for 16 h and then the precipitated triphenylphosphine oxide was filtered off 25 and washed with a little THF (10 ml). The filtrate and washings were combined and concentrated in 25 vacuo to a yellow syrup. This was absorbed from chloroform (3 ml) onto a column of silica gel (Merck Kieselgel 60, 200 g). Removal of the solvent afforded isomers of the title compound as a thick yellow brown syrup (3.52 g) which was used in the next stage without further purification.

iii) (E) and (Z)-1-(imidazol-2-yl)-1-[4-methyl)phenyl]-3-(1-pyrrolidyl)prop-1-ene

30 A solution of (E) and (Z)-1-[1-ethoxymethylimidazol-2-yl]-1-[4-methyl)phenyl]-3-(1- 39

pyrrolidyl)prop-1-ene (3.44 g) in ethanol (50 ml), water (50 ml) and conc. hydrochloric acid (3 ml) was heated on a steam bath for 6 days. The mixture was concentrated in vacuo and the residue partitioned between 2N sodium hydroxide (30 ml) and ethyl acetate (30 ml). The Z-isomer of the title compound crystallised out and was collected and recrystallised from ethyl acetate to give needles, m.p. 193—5° 35 (dec.) (0.44 g); t (CDCIa)—3.7 (1H, br.NH), 2.6—3.0 (6H, m, aromatic, imidazol) 4.02 35

(1H, t, =C

6.8 (2H, d, CH,N), 7.35 (4H, m,

H

,ch2—ch2

ch2—ch2

7.68 (3H, s, —CH3(, 8.15 (4H, m.

40

^ch2—ch2

)

ch2—ch2

40

45

The aqueous layer was extracted again with ethyl acetate (2x30 ml) and the combined extracts were washed with brine (10 ml) and dried (Na2S04). Removal of the solvent gave a sticky pale yellow solid (1.34 g) which was absorbed from dichloromethane (10 ml) onto 7 plates (20x20 cm, Merck alumina 150, F254). Elution with dichloromethane ethanol (30:1) afforded the (E) and (Z)-isomers of the title compound and these were extracted from the stationary phase with ethyl acetate.

A second crop of the Z-isomer had m.p. 191—194° (dec.) (0.31 g). The E-isomer crystallised

45

8

GB 2 062 626 A 8

from isopropyl acetate with m.p. 151—2° (dec.) (0.24g);r(CDCI3), 1.0 (1H, br,NH), 2.72, 2.85 (4H, m, aromatic), 3.02 (2H, s, imidazole), 3.23

/

(1H, t, =C )

\

H

6.88 (2H, d, CH2N<), 7.5 (4H, m.

7.62 (3H, s, —CH,), 8.3 (4H, m,

„ch2ch2

£h2ch2

.ch2ch2

ch2ch2

iv) 1-(lmidazol-2-yl)-1-(4-methylphenyl)-3-(1-pyrrolidyl)-propane

A solution of (Z)-1-(imidazol-2-yl)-1-[(4-methyl)phenyl]-3-(1-pyrrolidyl)prop-1-ene (0.31 g) in 10 absolute ethanol (40 ml) was hydrogenated over 10% palladium oxide on charcoal (0.03 g). Absorption of hydrogen was complete after 3 h. The catalyst was removed by filtration and the filtrate concentrated to a colourless oil which solidified. Recrystallisation from isopropyl acetate afforded the title compound as pale pink crystals m.p. 125—127 ° (0.21 g); r (CDCI3) 2.92 (4H, s, aromatic), 3.09

10

(2H, s, imidazole), 5.78 (1H, t,—CH—), 7.5 (8H, m,

15

7.68 (3H, s,—CH3), 8.2 (4H, m.

ch2ch2n

,ch2ch2

ch2ch2

,ch2ch2

ch2ch2

iv) (a) 1-(lmidazol-2-yl)-1-phenyl-3-(1-pyrrolidyl)propane (1.71 g) m.p. 131.5—132.5 (from ethyl acetate), v max (CHBr3) 3450 (NH), 1540 (C=N), 2800/2600 (CH2N<) was prepared in a similar 20 manner from a mixture of (Z) and (E)-1-(imidazol-2-yl)-1-phenyl-3-(1-pyrrolidyl)prop-1-ene (2.0 g).

15

20

Example 7

IM,N-Dimethyl-3-(imidazol-2-yl)-3-phenyl-1-propanamine

Hydrogen chloride was passed into a solution of a-(N,N-dimethylaminoethyl)benzeneacetonitriie (18.8 g) and dry methanol (6.3 ml) in dry dichloromethane (200 ml) for 8 h at 5—15°. Solvent was •25 removed to give a colourless oil which was taken up in dry methanol (150 ml) and treated with 2M 25

sodium methoxide solution (65 ml). Aminoacetaldehyde dimethyl acetal (10.6 g) was added and the mixture left to stand overnight. Methanol was then removed and the residue dissolved in 2N hydrochloric acid (200 ml) and heated at 80° for 30 min. The mixture was cooled, adjusted to pH 9.5 with potassium carbonate and extracted with ethyl acetate (3x200 ml). The extracts were washed 30 with brine (200 ml), concentrated and dried in vacuo to give the title compound, m.p. 135—136° 30

(16.3 g).

Example 8

IM,N-Dimethyl-3-(imidazol-2-yi)-3-phenyl-1 -propanamine hydrochloride

N,N-Dimethyl-3-(imidazol-2-yl)-3-phenyl-1-propanamine (2.3 g) was stirred with acetone (20 35 ml) and propan-2-ol (2 ml) and hydrochloric acid (concentrated, 1.0 ml) was added dropwise. 35

After stirring for 15 min the product was filtered, washed with acetone (25 ml) and air dried to give the title compound as a monohydrate, m.p. 102—104° (2.2 g).

oimax. (Nujol) 3500—2200 (—NH+), 3500 cm"' (H20).

GB 2 062 626 A

10

15

20

25

30

35

Example 9

N,N-Dimethyl-3-(imidazol)-2-yl)-3-phenyl-1-propanamine

Dry hydrogen chloride was bubbled into a solution of 4-dimethylamino-2-phenylbutyronitrile (1.88 g, 0.01 mol) and dry methanol (0.7 ml) in dichloromethane (20 ml) for 7.5 h keeping the temperature near to 0°. The solution was then diluted with ether to precipitate the imino ether dihydrochloride as an opaque gum (1.95 g) which was washed with dry ether then taken up into dry methanol (5 ml) and transferred to a 25 ml steel autoclave. Glycollic aldehyde (0.5 g) was added and then liquid ammonia (ca. 15 ml) and the mixture heated at 70—90° and 15—20 atmospheres for 4.5 h. Ammonia was allowed to evaporate off and the residual solution was diluted with water (50 ml) and extracted with ethyl acetate (50,4x25 ml). The extracts were washed with water (2x25 ml) and dried (Na2S04). Removal of the solvent gave a gum (0.58 g) which was absorbed from ethyl acetate (5 ml) and cyclohexane (5 ml) onto alumina (Merck 90, 30 g). Fractions eluted in cyclohexane-ethyl acetate (4:1, 100 ml) and (1:1, 50 ml) afforded the title compound which crystallised from ethyl acetate (5 ml) and cyclohexane (10 ml) as fine colourless needles, m.p. 132—134° (0.16 g).The mother liquors afforded a second crop m.p. 130—133 (0.036 g).

Example 10

(E)-1-(lmidazol-2-yl)-1-phenyl-3-(1-pyrrolidyl)prop-1-ene

A solution of n-butyl lithium in hexane (1.6 M, 6.5 ml) was added dropwise under nitrogen with stirring to a mixture of 2-( 1 -pyrrolidyDethyltriphenylphosphonium bromide (4.4 g) in dry THF (25 ml) to give a light orange solution of the ylid. After 30 minutes a solution of (1-ethoxymethylimidazol-2-yl)-phenylmethanone (2.3 g) in dry THF (25 ml) was added dropwise. The mixture was allowed to warm to room temperature over one hour and then boiled under reflux for twenty-two hours. The dark brown mixture was cooled, diluted with 2N hydrochloric acid (12 ml) and water (150 ml) and extracted with ethyl acetate (50,3x25 ml) then basified with sodium bicarbonate and again extracted with ethyl acetate (5x50 ml). The second extracts were dried (Na2S04) and removal of the solvent gave a mixture of the ethoxymethyl derivatives of the isomeric pyrrolidinopropenes as a viscous oil (2.38 g). This was taken up in concentrated hydrochloric acid (80 ml) and aqueous ethanol (1:1, 100 ml) and the solution boiled under reflux for 22 hours, then cooled, diluted with water (50 ml) and extracted with ether (100 ml). The solution was then basified with sodium bicarbonate and extracted with ethyl acetate (2x 100 ml, 4x50 mi). The extract was dried (Na2S04) and removal of the solvent gave a gum which slowly solidified (1.84 g).This was absorbed from methylene chloride (10 ml) onto six PLC plates (20x20 cm, Merck Al203, F254) and eluted with cyclohexane-ethyl acetate (9:1x1,1:1 x2). The deprotected isomeric propenes separated into two bands which were isolated from the stationary phase by Soxhlet extraction with ethyl acetate. Removal of the solvent gave the Z-isomer as an oil (0.4 g) and the E-isomer (1.1 g) the title compound, as an oil which crystallised to a solid m.p. 172—174° (0.25 g) on trituration with isopropyl acetate. Recrystallisation from isopropyl acetate gave fine needles, m.p. 173—174.5 pmax (CHBr3), 3400 (NH), 2800

ch2n

A,

10

15

20

25

30

35

40

Example 11

Pharmaceutical Compositions

40

45

50

55

(a) Tablets

Active ingredient Microcrystalline Cellulose B.P.C. Magnesium Stearate B.P.

Compression weight mg/tablet 50.00 149.00 1.00

200.00

The active ingredient is sieved through a 250 sieve, blended with the excipients and compressed using 8.5 mm punches. Tablets of other strengths may be prepared by increasing the compression weight and using punches to suit.

The tablet may be film coated with suitable film forming materials, e.g. methyl cellulose, or hydroxypropylmethyl cellulose, using standard techniques. Alternatively the tablets may be sugar coated.

(b) Capsules

Active ingredient •STA-RX 1500 Magnesium stearate B.P.

mg/capsule 50.00 49.50 0.50

45

50

55

*A form of directly compressible starch.

10

GB 2 062 626 A 10

The active ingredient is sieved through a 250 sieve and blended with the other materials. The mix is filled into No. 3 hard gelatin capsules using a suitable filling machine. Other doses may be prepared by increasing the fill weight and if necessary changing the capsule size to accommodate the increase.

5 c) Sustained Release Tablets

Active ingredient +Cutina HR Lactose B.P.

Magnesium stearate B.P.

+Cutina HR is a grade of microfine hydrogenated castor oil.

10

mg/tablet 200.00 50.00 247.50 2.50

10

15

The active ingredient is sieved through a 250 /urn sieve and blended with the Cutina HR and lactose. The mixed powders are moistened with Industrial Methylated Spirits 74 O.P., granules are made, dried, screened and blended with the magnesium stearate. The lubricated granules are compressed using 10.5 mm punches to produce tablets with a hardness of not less than 10 Kp (Schleuniger hardness tester).

15

(d) Syrup

20

25

Active ingredient Sucrose B.P. Glycerine B.P. Buffer Flavour Colour Preservative. Distilled water to mg/5 ml dose

50.00 2750.00 500.00

as required

5.0 ml

20

25

The active ingredient, buffer, flavour, colour and preservative are dissolved in some of the water, and the glycerine is added. The remainder of the water is heated to 80°C and the sucrose is dissolved in this and cooled. The two solutions are combined, adjusted to volume and mixed. The syrup produced 30 is clarified by filtration.

30

(e) Injection for Intravenous Administration

Active ingredient Water for injections B.P. to

% w/v 0.50 100.00

35 Sodium chloride may be added to adjust the tonicity of the solution and the pH may be adjusted to that of maximum stability using either dilute acid or alkali.

35

Claims

Claims

1. Compounds of the general formula (I)

40 and physiologically acceptable salts and bioprecursors thereof in which 40

>X—Y— represents either >CH—CH2 or >C=CH—; R1 represents hydrogen, halogen, C,_4 alkoxy, hydroxy, alkyl, R4CH(0H)—, cyano or R5CONH—; R2 and R3, which may be the same or different, each represents an alkyl group or alkenyl group or R2 and R3 may, together with the nitrogen atom to which they are attached, form a saturated heterocyclic ring containing from 5 to 7 members 45 which may optionally contain an oxygen atom; 45

R4 represents hydrogen or alkyl; and R5 represents hydrogen, alkyl or C1-4 alkoxy.

11

GB 2 062 626 A 11

2. Compounds as claimed in Claim 1 in which >X—Y— represents >CH—CH2, R1 represents a hydrogen atom, a halogen atom, or a methyl, methoxy, hydroxymethyl or 1-hydroxy-ethyl group and R2 and R3 both represent methyl groups or together with the nitrogen atom to which they are attached form a pyrrolidine ring.

5 3. Compounds as claimed in Claim 1 in which >X—Y— represents >C=CH—, R1 represents a 5

hydrogen atom or a methyl group and R2 and R3 together with the nitrogen atom to which they are attached form a pyrrolidine ring.

4. Compounds as claimed in Claim 3 in the form of the E-isomers.

5. Compounds as claimed in Claim 2 in which R1 is hydrogen, methoxy, hydroxymethyl or 1-

10 hydroxyethyl and R2 and R3 are both methyl. 10

6. N,N-Dimethyl-3-(imidazol-2-yl)-3-phenyl-1-propanamine and physiologically acceptable salts thereof.

7. The compound of claim 6 in the form of its hydrochloride salt.

8. A process for the preparation of compounds as claimed in Claim 1 which comprises

15 a) for the preparation of compounds in which >X—Y— represents >CH—CH2—, treating a 15

compound of formula (II)

r]

XI =^NH

^nhch2 ch (or6)2

ch2

| (ii)

ch2nr2r3

in which R1, R2, and R3 are as defined in Claim 1 and R6 represents a C,—C4 alkyl group or the two R6 groups may be linked together to form a cyclic acetal, with a dilute mineral acid;

20 W for the preparation of compounds in which >X—Y— represents >CH—CH2—, reacting an 20 amidine of formula (VII)

r] ~

•nh

Xk.^C

'ch nh2

ch2

(3zn)

ch2

nr2r3

in which R1, R2 and R3 are as defined in Claim 1, with glycollic aldehyde;

c) for the preparation of compounds in which >X—Y— represents >C=CH—, reacting a 2-25 benzoylimidazole of formula (VIII) 25

=1

C' . A>

(3zm)

in which R1 is as defined in Claim 1 and R8 is a hydrogen atom or a protecting group, with a triphenylphosphonium bromide (IX)

R2R3NCH2CH2P®Ph3 B©r (IX)

30 in which R2 and R3 are as defined in Claim 1, in the presence of a base, followed by removal of the 30

protecting group R8 if necessary:

d) for the preparation of compounds in which >X—Y— represents >CH—CH2—, reducing a compound of formula (I) in which >X—Y— represents >C=CH—, the compound optionally being in protected form, into the corresponding compound in which >X—Y— is >CH—CH2—;

35 e) for the preparation of compounds in which R1 represents a hydroxyalkyl group, reducing a 35

compound of formula (I) in which R1 represents a group convertible to a hydroxyalkyl group by reduction;

12

GB 2 062 626 A 12

f) for the preparation of compounds in which R1 represents the group R4CH(OH), reducing the corresponding alkanoyl compound with optional reduction of the group >C=CH—to >CH—CH2; or g) for the preparation of compounds in which R1 represents the group R5C0NH—, acylating the corresponding compound of formula (I) in which R1 represents—NH2.

5 9. A pharmaceutical composition comprising a compound as claimed in Claim 1 and at least one 5 inert pharmaceutically acceptable carrier or diluent, optionally together with at least one other active ingredient.

10. A pharmaceutical composition as claimed in Claim 8, in a form suitable for oral administration and containing 4 to 200 mg of the compound of Claim 1.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1981. Published by the Patent Office.

25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.