The present invention relates to new derivatives of 1- imidazolylalkyl-3-phenyl-imidazolidin-2-ones _r to a process for their preparation, to pharmaceutical compositions containing them and to their use as therapeutic agents, The present invention provides novel compounds having the general formula (I)

wherein n is 1 , 2 or 3; each of R, R and R , which may be the same or different, is hydrogen, halogen, hydroxy, cyano, C l-Cb. alkyl, CF 3_,

15 C l-C. alkoxy, C l.-C. alkylthio, formyl, C 2„-C b_ alkanoyl, carboxy, C -C. alkoxy-carbonyl, nitro, -N(R. R_ ) in l b 4 b which each of R and R independently is hydrogen, C -C alkyl, formyl or C -C. alkanoyl; or a (R. R_)N-S0„ group,

2 b b 7 2 in which each of R and R independently is hydrogen or

20 C -C. alkyl; 1 b

R is an imidazolyl group of formula

wherein each of R and R which may be the same or dif-

8 10 ferent is hydrogen or C -C. alkyl, R is hydrogen, C -C_ l b 9 l alkyl or a nitrogen protecting group; and the pharmaceu- tically acceptable salts thereof.

The formula reported above for the compounds according to the present invention includes all the possible isomers, as well as their mixtures. The invention includes within its scope the metabolites and the metabolic precursors or bio-precursors (other¬ wise known as pro-drugs) of the compounds of formula (I). Namely, the invention includes compounds which have a different formula to formula (I) above, but which never¬ theless upon administration to a human being are convert- ed directly or indirectly in vivo into a compound of formula (I) .

A halogen atom may be a fluorine, chlorine, bromine or iodine atom, preferably it is chlorine or bromine. The alkyl, alkenyl, alkynyl, alkoxy and alkylthio group may be a branched or straight chain group.

A C -C. alkyl group is preferably a C.-C. alkyl group, l 1 -4 e.g. methyl, ethyl, propyl, isopropyl, butyl, sec. butyl

or tert. butyl, in particular methyl or ethyl.

A C -C alkoxy group is preferably a C -C alkoxy group, e.g. ethoxy, ethoxy, propoxy, isopropoxy and butoxy, preferably methoxy and ethoxy. A C,-C_ alkylthio group is preferably a C -C„ alkylthio l b 1 4 group, e.g. methylthio, ethylthio, propylthio and butyl- thio, in particular methylthio.

A C -C alkanoyl group is e.g. a C -C alkanoyl group, in particular acetyl and propionyl. A nitrogen protecting group may be one of those employed usually in the chemistry of peptides, typically a tri- phenylmethyl , t-butyloxycarbonyl, benzyloxycarbonyl, acetyl, formyl, di(p-methoxyphenyl)methyl and (p-methoxyphenyl)diphenylmethyl. Pharmaceutically acceptable salts of the compounds of formula (I) include acid addition salts, with inorganic, e.g. nitric _; hydrochloric, hydrobromic, sulphuric, per¬ chloric and phosphoric acids, or organic, e.g. acetic, propionic, glycolic, lactic, oxalic, malonic, fumaric, malic, maleic, tartaric, citric, benzoic, cinnamic, man- delic and salicylic acids.

Preferred compounds of the invention are the compounds of formula (I) wherein each of R, R and R . which may be the same or different,is hydrogen,halogen,cyano,C -C alkyl, CF ₃ , C ₁ -C ₄ alkylthio, C ₁ ^< -C ₄ alkoxy or -N(R R ) in which

- A -

each of R and R independently is hydrogen, C -C alkyl, formyl or C -C alkanoyl; n is 1 or 2;

R is as defined above; each of R , R and R is independently hydrogen or C -C 8 9 10 1 4 alkyl; and the pharmaceutically acceptable salts thereof.

Examples of preferred compounds according to the inven¬ tion are the following:

l-( 5-methyl-lH-imidazol-4-yl )methyl-3-(3-chlorophenyl)- imidazolidin-2-one ; l-( 5-methyl-lH-imidazol-4-yl )methyl-3-phenyl-imidazolidin-

2-one ; l-( 5-methyl-lH-imidazol-4-yl )methyl-3-(3-bromophenyl)- imidazolidin-2-one ; l-(5-methyl-lH-imidazol-4-yl)methyl-3-(3-cyanophenyl)- imidazolidin-2-one ; l-( 5-methyl-lH-imidazoi-4-yl )methyl-3-(3-methylthio- phenyl )-imidazolidin-2-one ; l-(5-methyl-lH-imidazol-4-yl )methyl-3-(3-methylphenyl )- -imidazolidin-2-one;

1-(5-methyl-iH-imidazol-4-yl)methy1-3-(3,5-dime hylphenyl )- -imidazolidin-2-one; l-(5-methyl—lH-imidazol-4-yl)methyl-3-(3, 5-dichlorophenyl )- -imidazolidin-2-one ;

l-( iH-imidazol-4-yl)methyl-3-(3-chlorophenyl)-imidazolidin-

2-one ; l-( lH-imidazol-4-yl )methyl-3-phenyl-imidazolidin-2-one ;

1- ( lH-imidazol-4-yl )me thyl-3- ( 3-bromophenyl ) -imidazolidin-

2-one ;

1- ( lH-imidazol-4-yl )methyl-3- ( 3-cyanophenyl ) -imidazolidin-

2-one ; l-(lH-imidazol-4-yl)methyl-3-(3-methylthiophenyl)-imi- dazolidin-2-one; and the pharmaceutically acceptable salts thereof, in particular the hydroch]oride.

The compounds of the invention and the salts thereof can be obtained by a process comprising: a) reacting a compound of formula (II), or a salt there¬ of

wherein R, R and R are as defined above, with a compound of formula (III)

wherein n is as defined above, Y is a leaving group and in R , which is as defined above, R is C -C KM 9 1 b alkyl or a nitrogen protecting group,thus obtaining aa ccoommppoouunndd ooff ffoorrmmuullaa ((I) wherein R is as defined above bar hydrogen; or

b) deprotecting a compound of formula (IV)

wherein R , R , R and n are as defined above and R is a group of formula

wherein R _Q and R, _Λ are as defined above and R„ _ is a 8 10 12 nitrogen protecting group, thus obtaining a compound of formula (I), wherein R is hydrogen; and, if desired, converting a compound of formula (I) into another com- pound of formula (I), and/or, if desired, converting a compound of formula (I) into a pharmaceutically ac¬ ceptable salt thereof, and/or, if desired, converting a salt into a free compound, and/or, if desired, se¬ parating amixture of isomers of compounds of formula (I) into the single isomers.

A salt of a compound of formula (II) may be for example an alkali metal salt, preferably a sodium or potassium salt.

The salification of a compound of formula (II) may be performed according to known methods, e.g. by treatment with an alkaline hydride, preferably sodium hydride, or with lithium diisopropyla ide or an alkaline alkoxide, preferably potassium tert-butylate.

In a compound of formula (III) Y as a leaving group may be for example a halogen atom, typically chlorine, iodine or bromine, in particular chlorine; or the residue of a reactive ester, typically the residue of a reactive ester of an alcohol, in particular a sulfonyloxy derivative e.g. a mesyloxy or tosyloxy, more preferably a mesyloxy group. The reaction of a compound of formula (II), or a salt thereof, with a compound of formula (III) can be performed for instance in an anhydrous aprotic organic solvent e.g. dimethylformamide, dimethylacetamide or in other organic solvents e.g. toluene, tetrahydrofuran or dioxane, at temperatures ranging from about -10°C to reflux temperature, in the presence of a basic agent e.g. NaH or potassium tert- butylate. The deprotection of a compound of formula (IV) can be carried out according to known methods such as hydrolysis, for example acidic hydrolysis, for instance using an aqueous solution of halo-hydric acids, typically HC1 or HBr, or diluted sulphuric acid, or aqueous acetic acid, at a temperature ranging from room temperature to reflux temperature.

Alternatively the deprotection may be carried out by treatment with trifluoroacetic acid in an organic aprotic solvent, e.g. in methylene chloride, chloroform or carbonium tetrachloride, at a temperature ranging from room temperature to reflux temperature.

A compound of formula (I) can be converted, if desired, into another compound of formula (I) according to known methods. Thus for instance a compound of formula (I), wherein one or more of R, R and R ₂ is amino can be converted into another compound of formula (I) wherein one or more of R, R _x and R ₂ is C ₂ -C ₆ alkanoyla ino or formylamino.

A compound of formula (I) in which one or more of R, R__ and R ₂ is carboxy can be converted into another compound of formula (I) wherein one or more or R, R__ and R ₂ is Ca.-C ₆ alkoxycarbonyl, and vice versa. These optional conversions can be carried out by methods known in themselves. A compound of formula (I) wherein R ₉ is hydrogen may be converted into another compound of formula (I) wherein R ₉ is C -C ₆ alkyl, by following well known procedures, for example as described above as to the reaction of a compound of formula (II) with an alkylating agent of formula (III). For example a compound of formula (I) wherein one or more of R, Ra. and R ₂ is hydroxy may be converted into the respective compound of formula (I) wherein one or more of R, R _x and R ₂ is Ci-Cβ alkoxy by reaction with a suitable alkyl halide in the presence of a base such as NaOH, KOH,

Na CO , K CO , NaH, NaNH , sodium methoxide or sodium ethoxide, in a solvent selected from the group consist¬ ing, for example, of methanol, ethanol, dioxane, acetone, dimethylformamide, hexamethylphosphoramide, tetra- hydrofuran, water and their mixtures at a temperature ranging preferably between about 0°C and 70°C.

Furthermore, a compound of formula (I) wherein one or more of R, R and R is C -C. alkoxy may be converted in- 1 2 l to the respective compound of formula (I) wherein one or more of R, R and R is hydroxy, for example, by treat¬ ment with pyridine nydrochloride or with a strong acid such as HBr or H I, or with a Lewis acid such as A1C1 or BBr or with an alkaline salt of a thiol. Also the reduction of a compound of formula (I) wherein one or more of R, R and R- is nitro into the corres¬ ponding compound of formula (I) wherein one or more of R, R and R is amino may be carried out by known procedures, e.g. by catalytic hydrogenation and using preferably Pd/C as catalyst. Alkylation of a compound of formula (I) wherein one or more of R, R and R is amino may be carried out for example by reaction of a suitable C -C _e alkyl halide in

1 6 the presence of a base such as Na CO , K CO , NaH or NaNH , in a solvent such as dimethylformamide, dimethyl- acetamide, dioxane, tetrahydrofuran or their mixtures,

at a temperature varying between room temperature and about 100°C. Said alkylation process provides a mixture of N,N' dialkylated compounds of formula (I). The single alkylated compounds may be separed from the mixture ac- cording to well known methods, e.g. by silica gel column chromatography.

The optional salification of a compound of formula (I) as well as the conversion of a salt into the free com¬ pound and the separation of a mixture of isomers into the single isomers may be carried out by conventional methods.

When in the compounds described above groups are present which need to be protected during the reactions described above, such groups can be protected in a conventional way before the reaction takes place and then deprotected.

Examples of protecting groups are those employed usually in the chemistry of peptides.

The compounds of formula (II) are either known or may be obtained according to known methods e.g. as described in J. ed. Chem. , 9, 852 (1966).

The compounds of formula (III) are known or may be ob¬ tained by known methods.

The compounds of the invention are active on the sero- toninergic system, in particular as 5HT receptor antag- onists, as proven for example by the fact that they have

been found to be active in antagonizing the von Bezold- Jarisch chemoreflex evoked by 5-HT in the anesthetized rat according to the method described by Fozard J.R., Naunyn- Schmiedeberg's Arch. Pharmacol. 326, 36-44 (1984). The following Table I reports the in vivo 5HT ₃ antagonist activity data obtained in this test for a representative group of compounds of the invention.

TABLE I

Inhibition of the Bezold-Jarisch reflex elicited by 5-HT (20 ug/kg i.v.) by i.v. FCE-compounds in the anesthetized rat. Values are mean + S.E.M. from 6 animals.

p < 0.01 vs controls (Dunnett's test)

The affinity for serotonin 5-HT ₃ receptors was assessed for instance in rat entorhinal cortex using a selective radioligand 3H-BRL 43694 as described by Nelson and Thomas (1989).

NELSON D.R. and THOMAS D.R. , [3H]-BRL 43694 (Granisetron) , a specific ligand for 5-HT ₃ binding sites in rat brain cortical membranes, Biochem. Pharmac. , 38, 1693-1695, 1989. The affinity data for a representative group of compounds of the invention are set out in following Table II. TABLE II - 5-HT ₃ receptor binding test.

Compound 3H - BRL 43694

IC ₅₀ , nM

2.1 14

2.7 11

6.7

0.42

4

1.8 44

In the tables FCE 27733 means: 1-(5-methyl-lH-imidazol-4-yl)methγl-3-(3- -chlorophenyl)-imidazolidin-2-one;

FCE 28277 means l-(5-methyl-lH-imidazol-4-yl)methyl-3- -phenyl-imidazolidin-2-one;

FCE 28159 means : l-(5-methyl-lH-imidazol-4-γl)methyl-3-(3-

-bromophenγl)-imidazolidin-2-one; FCE 28276 means : l-(5-methyl-lH-imidazol-4-yl)methγl-3-

-(3-cγanophenγl)-imidazolidin-2-one; FCE 28278 means : l-(5-methyl-lH-imidazol-4-yl)methyl-3-

-(3- ethylthiophenyl)-imidazolidin-2-one; FCE 28232 means : l-(5-methyl-lH-imidazol-4-γl)methyl-3-

-(3,5-dichlorophenγl)-imidazolidin-2-one; FCE 28355 means : l-(5-methyl-lH-imidazol-4-yl)methyl-3-(3- -methylphenyl)-imidazolidin-2-one;

FCE 28356 means : 1-(5-methyl-lH-imidazol-4-yl)methyl-3-

-(3,5-dimethylphenyl)-imidazolidin-2-one; FCE 28307 means : l-(lH-imidazol-4-yl)methyl-3-phenyl-

-imidazolidin-2-one. in view of said activity, the compounds of the present invention can be useful, for example, in the treatment of CNS disorders such as, e.g., anxiety and psychosis, and/or in the treatment of gut motility disorders, and/or e esis. In view of the above activity, the compounds of the invention can be also useful as, for example, anti-migraine or anti¬ drug addiction agents, or as cognition activators. The dosage level suitable for administration to adult humans of the compounds of the invention, either for prophylaxis or therapeutic treatment, may range from about 0.010 to about 20 mg/kg of body weight, depending on the chosen route of administration, on the particular com-

pound chosen, on the particular patient under treatment and also on the nature and severity of the disorder. For instance for the compound of the invention l-(5- methyl-lH-imidazol-4-yl)methyl-3-(3-chlorophenyl)-imida- zolidin-2-one is suitable administered orally at a dos¬ age in this range.

Preferably the compounds may be, e.g., administered in single or divided doses such that the total daily dosage falls within the range of about 0.020 to about 10 mg/kg per day.

Of course, these dosage regimens may be adjusted to pro¬ vide the optimal therapeutic response.

The compounds of the invention can be administered in a variety of dosage forms, e.g. orally, in the form of tablets, capsules, sugar- or filn-coated tablets, liquid solutions or suspensions.

The invention includes pharmaceutical compositions com¬ prising a compound of the invention in association with a pharmaceutically acceptable excipient (which can be a carrier or diluent).

The nature of the pharmaceutical compositions containing the compounds of this invention in association with phar¬ maceutically acceptable carriers or diluents will, of course, depend upon the desired route of administration. The compositions may be formulated in the conventional

manner with the usual ingredients. For example, the com¬ pounds of the invention may be administered in the form of aqueous or oily solutions, or suspensions, tablets, pills, gelatine capsules, syrups, drops or suppositories. Thus, for oral administration, the pharmaceutical compo¬ sition containing the compounds of this invention are preferably tablets, pills or gelatine capsules which con¬ tain the active substance together with diluents, such as lactose, dextrose, sucrose, mannitol, sorbitol, cel- lulose; lubricants, for instance silica, talc, stearic acid, magnesium or calcium stearate, and/or polyethylene glycols; or they may also contain binders, such as starches, gelatine, methylcellulose, carboxymethylcel- lulose, gum-arabic, tragacanth, polyvinylpyrrolidone; disaggregating agents, such as starches, alginic acid, alginates, sodium starch glycolate; effervescing mixtures; dyestuffs; sweeteners; wetting agents, such as lecithin, polysorbates, laurylsulphates; and in general, non-toxic and pharmacologically inactive substances used in phar- maceuticai formulations. Said pharmaceutical preparations may be manufactured in known manner, for example by means of mixing, granulating, tabletting, sugar-coating, or film-coating processes. The liquid dispersions for oral administration may be e.g. syrups, emulsions and suspen- sions.

The syrups may contain as carrier, for example, saccha¬ rose or saccharose with glycerine and/or annitol and/ or sorbitol.

The suspensions and the emulsions may contain as carrier, for example, a natural gum, agar, sodium alginate, pec¬ tin, methylcellulose, carboxymethylcellulose, or poly- vinyl alcohol.

The suspensions or solutions for intramuscular injections may contain together with the active compound a pharma- ceutically acceptable carrier, e.g. sterile water, olive oil, ethyl oleate, glycols, e.g. propylene glycol, and if desired, a suitable amount of lidocaine hydrochloride. The solutions for intravenous injection or infusion may contain as carrier, for example, sterile water or prefer- ably they may be in the form of sterile aqueous isotonic saline solutions.

The suppositories may contain together with the active compound a pharmaceutically acceptable carrier e.g. cocoa-butter, polyethylene glycol, a polyoxyethylene sorbitan fatty acid ester surfactant or lecithin.

The following examples illustrate but do not limit the present invention.

Example 1

1-(5-methyl-l-triphenylmethyl-lH-imidazol-4-yl)methyl- 3-(3-chlorophenyl)-imidazolidin-2-one.

To a stirred solution of l-(3-chlorophenyl)-imidazol- idin-2-one (1.2 g; 0.0061 moles) in 20 ml of anhydrous dimethylformamide kept under nitrogen atmosphere, 50% NaH (0.3 g; 0.0062 moles) is added.

The solution is stirred for 1 hour at 60°C; then 4- -chloromethyl-5-methyl-l-triphenylmethyl-lH-imidazole (2.3 g; 0.0061 moles) is added at room temperature.

The mixture is stirred 6 hours at 90°C, then cooled, poured into water and extracted with methylene chloride. The organic layer is washed with brine, dried over an¬ hydrous sodium sulfate and, after filtration, evaporated to dryness. The residue is purified by silica gel flash- chromatography (ethyl acetate as eluant) to give 2.1 g of the desired product as a white solid (m.p. 189-191°C; C H C1 ₄ 0, required = C: 74.35; H: 5.48; N: 10.51; Cl: 6.65; found = C: 74.60; H: 5.55; N: 10.23; Cl: 6.43). By proceeding analogously, the following compounds can be prepared: l-(5-methyl-l-triphenylmethyl-lH-imidazol-4-yl)methyl-3- phenyi-imidazolidin-2-one,m.p. 196-198°C; l-(5-methyl-l-triphenylmethyl-lH-imidazol-4-yl)methyl-3- (3-bromophenyl)-imidazolidin-2-one, m.p.215-217°C; _l -(5-methyl-l-triphenylmethyl-lH-imidazol-4-yl)methyl-3 -

-(4-chlorophenyl)—imidazolidin-2-one;

1_(5-methyl-l-triphenylmethyl-lH-imidazol-4-yl)methyl-3-

-(2-chlorophenyl)-imidazolidin-2-one;

l- ( 5-methyl-l-triphenylmethyl-lH-imidazol-4-yl )methyl-3-

-(3-cyanophenyl)-imidazolidin-2-one; l-(5-methyl-l-triphenylmethyl-lH-imidazol-4-yl)methyl-3- -(3-methylthiophenyl)-imidazolidin-2-one, m.p. 206°C dec; l- ₍ 5-methyl-l-triphenylmethyl-lH-imidazol-4-yl)methyl-3-

(3-methylphenyl)-imidazolidin-2-one . l-(5-methyl-l-triphenylmethyl-lH-imidazol-4-yl)methyl-3-

-(3,5-dimethγlphenyl)-imidazolidin-2-one; l-(5-methyl-l-triphenylmethγl-lH-imidazol-4-yl)methyl-3- -(3,5-dichlorophenyl)-imidazolidin-2-one,m.p. 199-202°C;

l-(l-triphenylmethyl-lH-imidazol-4-yl)methyl-3-(3-chloro- phenyl)-iπidazolidin-2-one; l-(l-triphenylmethyl-lH-imidazol-4-yl)methyl-3-phenyl- imidazolidixi-2-one, m.p. 162-166°C; l-( l-triphenylmethyl-lH-imidazol-4-yl )methyl-3-(3-bromo- phenyl)-imidazolidin-2-one; l- ⁽ l-triphenylmethyl-lH-imidazol-4-yl)methyl-3-(3-cyano- phenyl)-imidazolidin-2-one; and l- ⁽ l-triphenylmethyl-lH-imidazol-4-yl)methyl-3-(3- methylthiophenyl ⁾ -imidazolidin-2-one.

Example 2

^l - ⁽ 5-methyl-lH-imidazol-4-yl)methyl-3-(3-chlorophenyl)- imidazolidin-2-one.

A solution of l- ⁽ 5-methyl-l-triphenylmethyl-lH-imidazol- ⁴ -yl ⁾ methyl-3- ⁽ 3-chlorophenyl ⁾ -imidazolidin-2-one (2 g;

0.0038 moles) in acetic acid (30 ml), water (30 ml) and tetrahydrofuran (30 ml) is heated at reflux for 1 hour.

The solution is cooled and poured into 1 N hydrochloric acid

(100 ml) and washed with ethyl acetate. The aqueous layer is basified with potassium carbonate (to pH 9) and extracted with methylene chloride. The organic layer is washed with brine and dried over anhydrous sodium sulfate and, after filtration, evaporated to dryness.

The residue is triturated with dry diethyl ether to give 0.8 g of the desired product as a white solid (m.p. 229.5-232.5°C dec; C ₁₄ H ₁₅ C1N ₄ 0, required = C: 57.83; H: 5.20; N: 19.27;

Cl: 12.20; found = C: 57.65; H: 5.32; N: 19.04; Cl: 12.53).

By proceeding analogously, the following compounds can be prepared: l-(5-methγl-lH-imidazol-4-yl)methyl-3-phenγl-imidazolidin- 2-

-one, m.p. 207-210.5°C; l-(5-methγl-lH-imidazol-4-γl)methγl-3-(3-bromophenyl)-imi da- zolidin-2-one, m.p. 233-238.5°C;

1-(5-methγl-lH-imidazol-4-yl)methyl-3-(3-cyanophenyl)-im ida- zolidin-2-one, m.p. 221-226°C;

1-(5-methγl-lH-imidazol-4-γl)methyl-3-(3-methylthiophen γl)-

-imidazolidin-2-one, m.p. 185-190°C;

1-(5-methyl-lH-imidazol-4-yl)methγl-3-(4-chlorophenyl)-i mi- dazolidin-2-one, m.p. 230-234°C; l-(5-methγl-lH-imidazol-4-γl)methγl-3-(2-chlorophenγl)-

-imidazolidin-2-one, m.p. 159.5-167.5°C;

l-(5-methyl-lH-imidazol-4-yl)methγl-3-(3-methγlphenyl)-

-imidazolidin-2-one, m.p. 216-221°C;

1-(5-methyl-lH-imidazol-4-yl)methyl-3-(3,5-dimethylphenyl )•

-imidazolidin-2-one, m.p. 246-249°C; 1-(5-methyl-lH-imidazol-4-yl)methyl-3-(3,5-dichlorophenyl)-

-imidazolidin-2-one, m.p. 242-249°C;

1-(lH-imidazol-4-yl)methyl-3-(3-chlorophenγl)-imidazolid in-

-2-one; l-(lH-imidazol-4-yl)methyl-3-phenyl-imidazolidin-2-one,m.p. 201-203°C; l-(lH-imidazol-4-yl)methyl-3-(3-bromophenγl)-imidazolidin-

-2-one; l-(lH-imidazol-4-γl)methγl-3-(3-cγanophenγl)-imidazolidi n-

-2-one; and l-(lH-imidazol-4-yl)methyl-3-(3-methylthiophenyl)-imidazoli- din-2-one.

Example 3 l-( 5-methγl-lH-imidazol-4-yl )methyl-3- ( 3-chlorophenγl ) -imida- zolidin-2-one hydrochloride . To a solution of l- ( 5-methyl-lH-imidazol-4-γl )methγl-3- ( 3- chlorophenγl ) -imidazolidin-2-one ( 0.6 g ; 0.00206 moles ) in

absolute ethanol (10 ml) an excess of a solution of hydrochloric acid in ethanol is added.

Diethyl ether is added. The precipitate is filtered to give

0.65 g of the desired product as a white solid, 245°C dec. By proceeding analogously, the following compounds can be prepared: l-(5-methyl-lH-imidazol-4-γl)methyl-3-phenyl-imidazolidin-

-2-one hydrochloride; l-(5-methyl-lH-imidazol-4-yl)methyl-3-(3-bromophenγl)- -imidazolidin-2-one hydrochloride; l-(5-methyl-lH-imidazol-4-yl)methγl-3-(3-cyanophenyl)-

-imidazolidin-2-one hydrochloride;

1-(5-methyl-lH-imidazol-4-γl)methγl-3-(3-methylthiophen yl)-

-imidazolidin-2-one hydrochloride; 1-(5-methγl-lH-imidazol-4-yl)methyl-3-(3-methylphenyl)-imid a- zolidin-2-one hydrochloride;

1-(5-methyl-lH-imidazol-4-yl)methγl-3-(3,5-dimethylpheny l)-

-imidazolidin-2-one hydrochloride;

1-(5-methγl-lH-imidazol-4-yl)methyl-3-(3,5-dichloropheny l)- -imidazolidin-2-one hydrochloride; l-(5-methγl-lH-imidazol-4-γl)methγl-3-(4-chlorophenyl)-im i- dazolidin-2-one hydrochloride;

1-(5-methγl-lH-imidazol-4-yl)methγl-3-(2-chlorophenγl) -

-imidazolidin-2-one hydrochloride;

1-(lH-imidazol-4-yl)methyl-3-(3-chlorophenyl)-imidazolidin- -2-one hydrochloride; l-(lH-imidazol-4-γl)methγl-3-phenyl-imidazolidin-2-one- hydrochloride; l-(lH-imidazol-4-yl)methyl-3-(3-bromophenγl)-imidazolidin-2 - -one hydrochloride; l-(lH-imidazol-4-γl)methγl-3-(3-cyanophenγl)-imidazolidin -2- -one hydrochloride; and

1-(lH-imidazol-4-γl)methyl-3-(3-methyIthiopheny1)-imidaz o- lidin-2-one hydrochloride.

Example 4 l-(l-ethγl-4-methγl-lH-imidazol-5-yl)methγl-3-phenγl-imi dazo- lidin-2-one hydrochloride.

To a solution of l-(5-methyl-lH-imidazol-4-yl)methyl-3- -phenyl-imidazolidin-2-one (1 g; 0.0039 moles in 20 ml of anhydrous dimethylformamide kept under nitrogen atmosphere,

50% NaH (0.198 g; 0.0041 moles) is added at 0°C. After 15 min, ethyl iodide (0.33 ml; 0.0041 moles) is added and stirring is continued for lh at room temperature. The mixture cooled at 0°C is poured into water and extracted with methylene chloride.

The organic layer is washed with brine, dried over anhydrous sodium sulfate and, after filtration, evaporated to dryness.

The residue is purified by silica gel flash-chromatography (ethyl acetate-methanol-30% ammonium hydroxide, 190:10:3 as eluant) and treated with an excess of a solution of hydro-

chloric acid in ethanol. The crude salt is collected by filtration and recrystallized from absolute ethanol to yield

0.21 g of the desired product as a white solid; m.p. 227-

230°C. By proceeding analogouly, the following compounds can be prepared: l-(l-ethγl-4-methγl-lH-imidazol-5-γl)methyl-3-(3-chloro- phenyl)-imidazolidin-2-one hydrochloride; l-(l,4-dimethγl-lH-imidazol-5-yl)methyl-3-(3-chlorophenγl) - -imidazolidin-2-one hydrochloride; and

1-(1,4-dimethyl-lH-imidazol-5-yl)methyl-3-phenyl-imidazo- lidin-2-one hydrochloride.

Example 5 l-(l-ethγl-5-methγl-lH-imidazol-4-yl)methγl-3-phenγl-imi da- zolidin-2-one hydrochloride.

The flash-chromatography of Example 4 gives a second eluted, which is treated with an excess of a solution of hydrochloric acid in ethanol. The crude salt is collected by filtration and recrystallized from absolute ethanol to yield 0.4 g of the captioned product as a white solid, m.p. 225-230°C.

By proceeding analogously, the following compounds can be prepared: l-(l-ethγl-5-methγl-lH-imidazol-4-yl)methyl-3-(3-chloro- phenyl)-imidazolidin-2-one hydrochloride; 1-(1r5-dimethγl-lH-imidazol-4-yl)methγl-3-(3-chlorophenγl )-

-imidazolidin-2-one hydrochloride; and

1-(1,5-dimethγl-lH-imidazol-4-γl)methγl-3-phenγl-imidazo - lidin-2-one hydrochloride.

Example 6

Tablets each weighing 150 mg and containing 60 mg of the active substance can be manufactured by blending and com¬ pressing the following ingredients:

l-(5-methyl-lH-imidazol-4-yl)methyl-3-

(3-chlorophenyl)-imidazolidin-2-one 60 mg

Starch 50 mg Cellulose microcrystalline 30 mg

Polyvinylpyrrolidone 5 mg

Sodium carboxymethyl starch 4.5 mg

Magnesium stearate 0.5 mg

Example 7 Capsules, each dosed at 200 mg and containing 80 mg of the active substance can be prepared as follows:

l-(5-methyl-lH-imidazol-4-yl)methyl-3- (3-chlorophenyl)-imidazolidin-2-one 80 mg Corn starch 60 mg

Cellulose microcrystalline 59 mg Magnesium stearate 1 mg

This formulation can be encapsulated in two-piece hard gelatin capsules and dosed at 200 mg for each capsule.