ANTI-ALLERGIC 2-(HETEROCYCLYL ALKYL) IMIDAZO PYRIDINES AND 2-(HETEROCYCLYL ALKYL) PURINES

Abstract: Antiallergic 2-(heterocyclylalkyl)imidazopyridines of formula wherein -A¹=A²-A³=A⁴- is -N=CH-CH=CH-, -CH=N-CH=CH-, -CH=CH-N=CH-, -CH=CH-CH=N-, -N=CH-N=CH- or -CH=N-CH=N-; R¹ is hydrogen, C₁₋₁₀alkyl, C₃₋₆cycloalkyl, Ar¹, C₁₋₆alkyl or a radical of formula -Alk-G-R²; R is hydrogen or C₁₋₆alkyl; m is 1 to 4; n is 1 or 2; L is hydrogen, C₁₋₆alkylcarbonyl, C₁₋₆alkylsulfonyl, C₁₋₆alkyloxycarbonyl, Ar²-C₁₋₆alkyloxycarbonyl, Ar²-carbonyl, Ar²-­ sulfonyl, C₃₋₆cycloalkyl, C₂₋₆alkenyl optionally substituted with Ar², C₁₋₁₂alkyl, a radical of formula -Alk-R⁴, -Alk-Y-R⁵, Alk-Z¹-C(X)-Z²-R⁶ or -CH₂-CHOH-CH₂-O-R⁷; the pharmaceutically acceptable acid addition salts and possible stereochemically isomeric forms thereof, novel compounds of formula (I); pharmaceutical compositions containing such compounds as an active ingredient and methods of preparing said compounds and pharmaceutical compositions.

Description: Background of the invention : In published European Patent Application No. 123,962 and in Journal of Heterocyclic Chemistry, 24 , 31-37 there are described a number of 2-heterocyclylmethyl-1-alkoxyethylbenzimidazole derivatives as compounds possessing antihistaminic activity. A number of 2-heterocyclylmethyl-1-benzylimidazo[4,5-b]- and imidazo[4,5-c]pyridines are described in Liebigs Ann. Chem. 747 , 158-171 (1971) as compounds possessing inflammatory reducing properties. In J. Heterocyclic Chem. 20 , 1339 (1983) there is described the preparation of the compound 3-(methylphenyl)-2-[(4-methyl-1-piperazinyl)methyl]-3 H -imidazo[4,5-b]pyridine. Belgium Patent No. 667,333 on the other hand teaches 2-(piperazinylalkyl)-1-substituted benzimidazoles possessing antihypertensive and anti-allergic properties. Description of the invention: The present invention is concerned with the use of a compound having the formula a pharmaceutically acceptable acid addition salt thereof, or a stereochemically isomeric form thereof, for the manufacture of a medicament for treating allergic diseases, wherein -A¹=A²-A³=A⁴- is a bivalent radical having the formula -N=CH-CH=CH- (a-1), -CH=N-CH=CH- (a-2), -CH=CH-N=CH- (a-3), -CH=CH-CH=N- (a-4), -N=CH-N=CH- (a-5), or -CH=N-CH=N- (a-6), wherein one or two hydrogen atoms in said radicals (a-1) - (a-6) may, each independently from each other, be replaced by halo, C₁₋₆alkyl, C₁₋₆alkyloxy, trifluoromethyl or hydroxy; R¹ is hydrogen, C₁₋₁₀alkyl, C₃₋₆cycloalkyl, Ar¹, C₁₋₆alkyl substituted with one or two Ar¹ radicals, or a radical of formula -Alk-G-R²; wherein R² is hydrogen; C₂₋₆alkenyl optionally substituted with Ar²; C₃₋₆alkynyl; Ar¹ or C₁₋₆alkyl optionally substituted with Ar¹, hydroxy, C₁₋₆alkyloxy, carboxyl, C₁₋₆alkyloxycarbonyl, Ar²-oxycarbonyl or Ar²-C₁₋₆alkyloxycarbonyl; and G is O, S or NR³; said R³ being hydrogen, C₁₋₆alkyl, C₁₋₆alkylcarbonyl, C₁₋₆alkyloxycarbonyl or Ar²-C₁₋₆alkyl; R is hydrogen or C₁₋₆alkyl; m is 1 to 4; n is 1 or 2; L is hydrogen, C₁₋₆alkylcarbonyl, C₁₋₆alkylsulfonyl, C₁₋₆alkyloxycarbonyl, Ar²-C₁₋₆alkyloxycarbonyl, Ar²-carbonyl, Ar²-sulfonyl, C₃₋₆cycloalkyl, C₂₋₆alkenyl optionally substituted with Ar², C₁₋₁₂alkyl, a radical of formula -Alk-R⁴ (b-1) -Alk-Y-R⁵ (b-2) -CH₂-CHOH-CH₂-O-R⁷ (b-4); wherein R⁴ is Ar², Het, cyano, isocyanato, isothiocyanato, Ar²-sulfonyl or halo; R⁵ is hydrogen, Ar², Het or C₁₋₆alkyl optionally substituted with halo, Ar² or Het; R⁶ is hydrogen, Ar², Het or C₁₋₆alkyl optionally substituted with halo, Het or Ar²; R⁷ is Ar² or naphthalenyl; Y is O, S, NR⁸; said R⁸ being hydrogen, C₁₋₆alkyl, C₁₋₆alkylcarbonyl or Ar¹-carbonyl; Z¹ and Z² each independently are O, S, NR⁹ or a direct bond; said R⁹ being hydrogen or C₁₋₆alkyl; X is O, S or NR¹⁰; said R¹⁰ being hydrogen, C₁₋₆alkyl or cyano; and each Alk independently being C₁₋₆alkanediyl; Het is a five- or six-membered heterocyclic ring containing 1, 2, 3 or 4 heteroatoms, said heteroatoms being selected from oxygen, sulfur and nitrogen, provided that no more than two oxygens or sulfurs are present, said five or six-membered ring being optionally condensed with a five- or six-membered carbocyclic or heterocyclic ring also containing 1, 2, 3 or 4 heteroatoms, the latter heteroatoms being selected from oxygen, sulfur and nitrogen, provided that no more than 2 oxygens or sulfurs are present, and when said Het is a bicyclic ring system it may optionally be substituted with up to 6 substituents, and when said Het is a monocyclic ring system it may optionally be substituted with up to 4 substituents, said substituents of Het being selected from a bivalent radical of formula =X; halo; isocyanato; isothiocyanato; nitro; cyano; trifluoromethyl; a radical of formula -A; a radical of formula -Y-A; or a radical of formula -Z¹-C(=X)-Z²-A; wherein said =X independently has the same meaning of the previously defined X and A is hydrogen, Ar² or C₁₋₆alkyl being optionally substituted with Ar², C₁₋₆alkyloxy, Ar²-O, hydroxy, or C₁₋₆alkyloxycarbonyl; and Y, Z¹ and Z² independently have the same meaning of the previously defined Y, Z¹ and Z²; provided that (i) when in the radical -Y-A, A is hydrogen, then Y is other than a direct bond, or (ii) when in the radical -Z¹-C(=X)-Z²-A, A is hydrogen and Z¹ is NR⁹, O or S, then Z² is other than O or S; preferably the sum of heteroatoms in the above defined Het is less than 6; Ar¹ is phenyl, being optionally substituted with 1, 2 or 3 substituents each independently selected from halo, hydroxy, nitro, cyano, trifluoromethyl, C₁₋₆alkyl, C₁₋₆alkyloxy, C₁₋₆alkylthio, mercapto, amino, mono- and di(C₁₋₆alkyl)amino, carboxyl, C₁₋₆alkyloxycarbonyl and C₁₋₆alkylcarbonyl; thienyl; halothienyl; furanyl; C₁₋₆alkyl substituted furanyl; pyridinyl; pyrimidinyl; pyrazinyl; thiazolyl or imidazolyl optionally substituted with C₁₋₆alkyl; and Ar² is phenyl being optionally substituted with 1, 2 or 3 substituents each independently selected from halo, hydroxy, nitro, cyano, trifluoromethyl, C₁₋₆alkyl, C₁₋₆alkyloxy, C₁₋₆alkylthio, mercapto, amino, mono- and di(C₁₋₆alkyl)amino, carboxyl, C₁₋₆alkyloxycarbonyl and C₁₋₆alkylcarbonyl. An additional feature of the present invention comprises the fact that most of the compounds of formula (I) are novel. These novel compounds are the compounds of formula (I) as defined hereinabove, with the proviso that when L is C₁₋₂alkyl, R¹ is other than hydrogen, 2-methylphenyl, benzyl, 4-chlorobenzyl or 4-methoxybenzyl. As used in the foregoing definitions the term "halo" is generic to fluoro, chloro, bromo and iodo; the term "C₁₋₆alkyl" is meant to include straight and branch chained saturated hydrocarbon radicals having from 1 to 6 carbon atoms such as, for example, methyl, ethyl, 1-methylethyl, 1,1-dimethylethyl, propyl, 2-methylpropyl, butyl, pentyl and hexyl; "C₁₋₁₂alkyl" is meant to include C₁₋₆alkyl radicals, as defined hereinabove, and the higher homologs thereof having from 7 to 12 carbon atoms; the term "C₃₋₆cycloalkyl" is generic to cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl; the term "C₂₋₆alkenyl" defines straight and branch chained hydrocarbon radicals containing one double bond and having from 2 to 6 carbon atoms such as, for example, ethenyl, 2-propenyl, 3-butenyl, 2-butenyl, 2-pentenyl, 3-pentenyl, or 3-methyl-2-butenyl; "C₃₋₆alkynyl" defines straight and branch chain hydrocarbon radicals containing one triple bond and having from 3 to 6 carbon atoms such as, for example, propargyl, 2-butynyl, 3-butynyl, 2-pentynyl, 3-pentynyl or 4-pentynyl; and when a C₃₋₆alkenyl or C₃₋₆-alkynyl is substituted on a heteroatom, then the carbon atom of said C₃₋₆alkenyl or C₃₋₆alkynyl connected to said heteroatom preferably is saturated. It is clear that the C m H 2m moiety comprises as well straight as branch chained bivalent saturated hydrocarbon radicals. The said acid addition salts as mentioned hereinabove are meant to comprise the therapeutically active non-toxic acid addition salt forms which the compounds of formula (I) are able to form. The latter can conveniently be obtained by treating the base form whith appropriate acids such as, for example, inorganic acids, such as hydrohalic acid, e.g. hydrochloric or hydrobromic, and sulfuric acid, nitric acid or phosphoric acid; or organic acids, such as, for example, acetic, propanoic, hydroxyacetic, 2-hydroxypropanoic, 2-oxopropanoic, ethanedioic, propanedioic, butanedioic, (Z)-2-butenedioic, (E)-2-butenedioic, 2-hydroxybutanedioic, 2,3-dihydroxybutanedioic, 2-hydroxy-1,2,3-propanetricarboxylic, methanesulfonic, ethanesulfonic, benzenesulfonic, 4-methylbenzenesulfonic, cyclohexanesulfamic, 2-hydroxybenzoic, or 4-amino-2-hydroxybenzoic acids. Conversely the salt form can be converted by treatment with alkali into the free base form. The compounds of formula (I) containing acidic protons may also be converted to their therapeutically active non-toxic metal or amine substitution salt forms by treatment with appropriate organic or inorganic bases. The term acid addition salt also comprises the hydrates and solvent addition forms which the compounds of formula (I) are able to form. Examples of such forms are e.g. hydrates or alcoholates. From formula (I) it is clear that the compounds of this invention may have several asymmetric carbon atoms in their structure. Pure isomeric forms of the compounds of formula (I) can be separated from the mixture by conventional separation methods. Preferably, if a specific stereoisomer is desired, said compound will be synthesized by stereoselective methods of preparation. These methods will advantageously employ enantiomerically pure starting materials. It is evident that in the compounds of formula (I) wherein R⁴, R⁵ or R⁶ is Het, said Het may be unsaturated or partly or completely saturated. The compounds of formula (I) wherein Het is a heterocycle which is substituted with a hydroxy, mercapto or amino radical may contain in their structure a keto-enol tautomeric system or a vinylogous system thereof, and consequently the compounds may be present in their keto forms as well as their enol form. Particularly, Het may be (i) an optionally substituted five- or six-membered heterocyclic ring containing 1, 2, 3 or 4 heteroatoms selected from oxygen, sulfur and nitrogen, provided that no more than two oxygens or sulfurs are present; or Het may be (ii) an optionally substituted five- or six-membered heterocyclic ring containing 1 or 2 heteroatoms selected from oxygen, sulfur and nitrogen, being fused with an optionally substituted five- or six-membered ring through two ring carbon atoms or one ring carbon and one ring nitrogen atom, containing in the remainder of the fused ring only carbon atoms; or Het may be (iii) an optionally substituted five- or six-membered heterocyclic ring containing 1 or 2 heteroatoms selected from oxygen, sulfur and nitrogen, being fused with an optionally substituted five- or six-membered heterocyclic ring through two ring carbon atoms or one ring carbon and one ring nitrogen atom, containing in the remainder of the fused ring 1 or 2 heteroatoms selected from oxygen, sulfur and nitrogen; wherein Het may optionally be substituted with up to 4 substituents when Het is a monocyclic ring system, and wherein Het may optionally be substituted with up to 5 substituents when Het is a bicyclic ring system, said substituents being the same as previously described. In more detail Het is a member selected from pyridinyl which is optionally substituted with one or two substituents each independently selected from halo, amino, mono- and di(C₁₋₆alkyl)amino, Ar²-C₁₋₆alkylamino, nitro, cyano, aminocarbonyl, C₁₋₆alkyl, C₁₋₆alkyloxy, C₁₋₆alkylthio, C₁₋₆alkyloxycarbonyl, hydroxy, C₁₋₆alkylcarbonyloxy, Ar²-C₁₋₆alkyl and carboxyl; pyridinyloxide optionally substituted with nitro; pyrimidinyl which is optionally substituted with one or two substituents each independently selected from the group consisting of halo, amino, C₁₋₆alkylamino, Ar²-C₁₋₆alkylamino, hydroxy, C₁₋₆alkyl, C₁₋₆alkyloxy, C₁₋₆alkylthio and Ar²-C₁₋₆alkyl; pyridazinyl which is optionally substituted with C₁₋₆alkyl or halo; pyrazinyl which is optionally substituted with halo, amino or C₁₋₆alkyl; thienyl which is optionally substituted with halo or C₁₋₆alkyl; furanyl which is optionally substituted with halo or C₁₋₆alkyl; pyrrolyl which is optionally substituted with C₁₋₆alkyl; thiazolyl which is optionally substituted with C₁₋₆alkyl, C₁₋₆alkyloxycarbonyl, Ar² or Ar²-C₁₋₆alkyl; imidazolyl which is optionally substituted with one or two substituents each independently selected from C₁₋₆alkyl, Ar²-C₁₋₆alkyl and nitro; tetrazolyl which is optionally substituted with C₁₋₆alkyl; 1,3,4-thiadiazolyl which is optionally substituted with C₁₋₆alkyl; 5,6-dihydro-4 H -1,3-thiazin-2-yl which is optionally substituted with C₁₋₆alkyl; 4,5-dihydrothiazolyl which is optionally substituted with C₁₋₆alkyl; oxazolyl which is optionally substituted with C₁₋₆alkyl; 4,5-dihydro-5-oxo-1 H -tetrazolyl which is optionally substituted with C₁₋₆alkyl; 1,4-dihydro-2,4-dioxo-3(2 H )-pyrimidinyl being optionally substituted with C₁₋₆alkyl; 4,5-dihydro-4-oxopyrimidinyl optionally substituted with up to 3 substituents selected from C₁₋₆alkyl, amino, C₁₋₆alkylaminocarbonylamino, Ar²-aminocarbonylamino, Ar²-C₁₋₆alkyl-amino and C₁₋₆alkylamino; 2-oxo-3-oxazolidinyl; indolyl which is optionally substituted with hydroxy or C₁₋₆alkyl; quinolinyl which is optionally substituted with hydroxy or C₁₋₆alkyl; quinazolinyl which is optionally substituted with hydroxy or C₁₋₆alkyl; quinoxalinyl which is optionally substituted with C₁₋₆alkyl; phthalazinyl which is optionally substituted with halo; 1,3-dioxo-1 H -isoindol-2(3 H )-yl; 2,3-dihydro-3-oxo-4 H -benzoxazinyl and 2,3-dihydro-1,4-benzodioxinyl, both being optionally substituted with C₁₋₆alkyl or halo; dioxanyl being optionally substituted with C₁₋₆alkyl; 2-oxo-2 H -1-benzopyranyl and 4-oxo-4 H -1-benzopyranyl both being optionally substituted with C₁₋₆alkyl; morfolinyl; thiomorfolinyl; piperidinyl; pyrolidinyl and a radical of formula wherein X¹ and X² are each independently O or S; R¹¹ , R¹² , R¹⁴ , R²² and R²⁴ are each independently hydrogen, C₁₋₆alkyl, Ar²-C₁₋₆alkyl, C₁₋₆alkyloxyC₁₋₆alkyl, hydroxyC₁₋₆alkyl or C₁₋₆alkyloxycarbonyl; R¹³ , R¹⁵ , R¹⁶ , R¹⁷ , R¹⁸ , R¹⁹ , R²⁰ , R²¹ and R²³ are each independently hydrogen, C₁₋₆alkyl, hydroxy, mercapto, C₁₋₆alkyloxy, C₁₋₆alkylthio, halo and (C₁₋₆alkyloxycarbonyl)C₁₋₆alkyl; G¹ is -CH=CH-CH=CH-, -S-CH=CH- or -N=CH-NH-; G² is -CH=CH-CH=CH-, -S-(CH₂)₂-, -S-(CH₂)₃-, -(CH₂)₄-, -S-CH=CH-, -HN-CH=CH-, -NH-(CH₂)₂- or -NH-(CH₂)₃-; G³ is -CH=CH-CH=CH-, -CH₂-NH-(CH₂)₂-, -S-CH=CH-, -S-(CH₂)₃-, -N=CH-CH=CH-, -CH=N-CH=CH-, -CH=CH-N=CH-, -CH=CH-CH=N-, -N=CH-N=CH- or -CH=N-CH=N-; G⁴ is -CH=CH-CH=CH-, -CH₂-NH-(CH₂)₂-, -N=CH-CH=CH-, -CH=N-CH=CH-, -CH=CH-N=CH-, -CH=CH-CH=N-, -N=CH-N=CH- or -CH=N-CH=N-; G⁵ is -CH=CH-CH=CH-, -N=CH-CH=CH-, -CH=N-CH=CH-, -CH=CH-N=CH-, -CH=CH-CH=N-, -N=CH-N=CH- or -CH=N-CH=N-; G⁶ is -CH=CH-CH=CH-, -N=CH-CH=CH-, -CH=N-CH=CH-, -CH=CH-N=CH-, -CH=CH-CH=N-, -N=CH-N=CH- or -CH=N-CH=N-; wherein one or two hydrogen atoms in said radicals G¹, G², G³, G⁴, G⁵ or G⁶ or in the benzene part of the radicals of formula (c-2) or (c-3) may be replaced by C₁₋₆alkyl, C₁₋₆alkylthio, C₁₋₆alkyloxy or halo where said hydrogen atom is bonded on a carbon atom, or by C₁₋₆alkyl, C₁₋₆alkyloxycarbonyl, Ar²-C₁₋₆alkyl, where said hydrogen is bonded on a nitrogen atom; An interesting subgroup among the compounds of formula (I) comprises those compounds of formula (I) wherein -A¹=A²-A³=A⁴- is a bivalent radical having a formula (a-1) through (a-4), with (a-1) being the most interesting subgroup. Another interesting subgroup among the compounds of formula (I) comprises those compounds of formula (I) wherein -A¹=A²-A³=A⁴- is a bivalent radical having the formula (a-5) or (a-6). Among the above subgroups those compounds of formula (I) are preferred wherein Het is the particular Het described hereinabove. Particularly preferred compounds within the invention are those preferred compounds of formula (I) wherein R¹ is C₁₋₆alkyl substituted with Ar¹ or wherein R¹ is a radical -Alk-O-R², said R² being hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆alkynyl or Ar¹. More particularly preferred compounds within the invention are those particularly preferred compounds wherein R is hydrogen, m is 1, n is 1, and L is hydrogen, C₁₋₆alkyl or a radical of formula (b-1), (b-2) or (b-3). Especially preferred compounds are those more particularly preferred compounds wherein R⁴ is Ar² or Het, R⁵ and R⁶ are C₁₋₄alkyl , Ar² or Het, R⁸ is hydrogen or C₁₋₄alkyl, X is O or S, and Z¹ and Z² are each independently NH or a direct bond. More especially preferred compounds are those especially preferred compounds wherein R¹ is an ethoxyethyl radical. The compounds of formula (I) can generally be prepared by cyclizing either an intermediate of formula (II-a) or an intermediate (II-b). In (II-a) and (II-b) X³ denotes O, S or NH. The cyclization reaction of (II-a) or (II-b) may be conducted in a suitable solvent such as, for example, a hydrocarbon, e.g., benzene, methylbenzene, dimethylbenzene, or hexane; an ether, e.g., 1,1′-oxybisethane or tetrahydrofuran; a ketone, e.g., 2-propanone or 2-butanone; an alcohol, e.g., methanol, ethanol, 2-propanol or 1-butanol; a halogenated hydrocarbon, e.g., trichloromethane or dichloromethane, a polar aprotic solvent, e.g., N , N -dimethylformamide or N , N -dimethylacetamide; an organic acid, e.g., acetic acid or propanoic acid; an aqueous solution of a mineral acid, e.g., hydrochloric acid; and mixtures of such solvents. In order to enhance the reaction rate, it may be advantageous to heat the reaction mixture, preferably to the reflux temperature of the reaction mixture. In some instances, especially where X³ is O, the cyclization reaction of (II-a) or (II-b) may be conducted in the presence of a suitable dehydrating agent such as, for example, polyphosphoric acid, phosphorous pentoxide, phosphoryl chloride, pentachlorophosphorane, or 4-methylbenzenesulfonic acid. According similar cyclization procedures as described above compounds of formula (I) may be prepared by reacting an acid of formula (IV) or a functional derivative thereof with a diamine of formula (III). Said functional derivative of (IV) is meant to comprise the halide, anhydride, amide, and ester form of (IV), including the ortho and imino ester form thereof. In a preferred method of conducting the above reaction there is used an imino ester form of (IV). The desired compounds of formula (I), are thus prepared by stirring the reactants at room temperature or at an elevated temperature in an acidic medium such as, for example acetic acid, or a lower alkanol, whereto an appropriate acid, e.g., hydrochloric acid has been added. However, when the imino ester is in the form of an acid addition salt there is no need for adding additional acid. Depending on the nature of (IV) and the reaction conditions, intermediates of formulae (II-a) or (II-b) may be generated, which may in situ, or if desired, after isolation and purification, by cyclized to obtain the compounds of formula (I). The compounds of formula (I) can also be obtained by reacting a piperazine or hexahydro-1 H -1,4-diazepine derivative of formula (V) with an imidazopyridine or imidazopyrimidine derivative of formula (VI) following art-known N -alkylation procedures. In the reaction of (V) with (VI) and in the following reaction schemes W represent and appropriate leaving group such as, for example, halo, e.g., chloro, bromo or iodo, or a sulfonyloxy group, e.g., methylsulfonyloxy or 4-methylphenylsulfonyloxy. Said N -alkylation reaction of (V) with (VI) may conveniently be conducted by stirring the reactants in the presence of a suitable organic solvent such as, for example, an aromatic hydrocarbon, e.g., benzene, methylbenzene or dimethylbenzene; a ketone, e.g., 2-propanone or 4-methyl-2-pentanone; an ether, e.g., 1,4-dioxane, 1,1′-oxybisethane or tetrahydrofuran; a polar aprotic solvent, e.g., N , N -dimethylformamide, N , N -dimethylacetamide , dimethyl sulfoxide, 1-methyl-2-pyrrolidinone, acetonitrile, hexamethylphosphor triamide, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1 H )-pyrimidinone or 1,3-dimethyl-2-imidazolidinone, benzonitrile; an excess of (V); and mixtures of such solvents. Somewhat elevated temperatures may be appropriate to enhance the rate of the reaction and in some cases the reaction may even be carried out at the reflux temperature of the reaction mixture. The addition of an appropriate base such as, for example, an alkali or an earth alkaline metal carbonate, hydrogen carbonate, hydroxide, amide or hydride, e.g., sodium hydroxide, potassium hydroxide, potassium carbonate or sodium hydride or an organic base, such as, for example, N , N -dimethyl-4-pyridinamine, pyridine, N , N -diethylethanamine or N -(1-methylethyl)-2-propanamine may be employed to pick up the acid which is liberated during the courses of the reaction. The compounds of formula (I) may also be prepared by reacting a piperazine or hexahydro-1 H -1,4-diazepine derivative of formula (V) with the corresponding carbonyl-oxidated form of the imidazopyridine or imidazopyrimidine derivative of formula (VI), following art-known reductive N -alkylation procedures. Said reductive N -alkylation reaction may conveniently be carried out by catalytically hydrogenating a stirred and/or heated mixture of the reactants in a suitable reaction inert organic solvent according to art-known catalytic hydrogenating procedures. Suitable solvents are, for example, water; alkanols, e.g., methanol, ethanol or 2-propanol; cyclic ethers, e.g., 1,4-dioxane; halogenated hydrocarbons, e.g., trichloromethane; N , N -dimethylformamide or dimethyl sulfoxide; or a mixture of such solvents. The term "art-known catalytic hydrogenating procedures" means that the reaction is carried out under hydrogen atmosphere in the presence of an appropriate catalyst such as, for example, palladium-on-charcoal or platinum-on-charcoal. In order to prevent the undesired further hydrogenation of certain functional groups in the reactants and the reaction products it may be advantageous to add an appropriate catalyst-poison to the reaction mixture, e.g., thiophene. The compounds of formula (I) may further be synthesized by reacting a piperazine or hexahydro-1 H -1,4-diazepine derivative of formula (VIII) with an imidazopyridine or imidazopyrimidine of formula (IX) or preferably with the corresponding two metal substitution form of (IX). The alkylation reaction of (VIII) with (IX) may be carried out in the usual manner, e.g. by stirring the reactants at ambient or lower temperatures in an appropriate organic solvent such as, for example, an ether, e.g. 1,4-dioxane, 1,1′-oxybisethane, tetrahydrofuran; a halogenated hydrocarbon, e.g., trichloromethane. The compounds of formula (I) can also be converted into each other. Some examples of such conversions will be described hereinafter. The compounds of formula (I) wherein R¹ is other than hydrogen, said radical being represented by R 1-a and said compounds by formula (I-a), can be prepared by N -alkylating a compound of formula (I-b) with an appropriate reagent of formula (X) according to the hereinbefore described N -alkylation procedures. In order to simplify the structural representations of the compounds of formula (I) and of certain precursors and intermediates thereof the -radical will hereafter be represented by the symbol D. The compounds of formula (I) wherein L is other then hydrogen, said L being represented by L¹, and said compounds being represented by formula (I-c) can generally be prepared by N -alkylating a compound of formula (I) wherein L is hydrogen, said compounds being represented by formula (I-d), with a reagent of formula (XI). Said N -alkylation is conveniently carried out according to art-known N -alkylation procedures described hereinabove for the preparation of (I) starting from (V) and (VI). The compounds of formula (I) wherein L is C₃₋₆cycloalkyl, C₁₋₁₂alkyl, a radical of formula (b-1), (b-2) or (b-3) said radical L being represented by the radical L²H-, and said compounds being represented by formula (I-c-1) can also be prepared by the reductive N -alkylation reaction of (I-d) with an appropriate ketone or aldehyde of formula L²=O (XII), said L²=O being an intermediate of formula L²H₂ wherein two geminal hydrogen atoms are replaced by =O, and L²= is a geminal bivalent radical comprising C₃₋₆cycloalkylidene, C₁₋₁₂alkylidene, R⁴-C₁-₆alkylidene, R⁵-Y-C₁₋₆alkylidene and R⁶-Z²-C(=X)-Z¹-C₁₋₆alkylidene. Said reductive N -alkylation is conveniently carried out according to art-known reductive N -alkylation procedures described hereinabove for the preparation of (I) starting from (V) and (VII). The compounds of formula (I) wherein L is a radical of formula (b-2) wherein R⁵ is Ar² or Het, said R⁵ being represented by R 5-a and said compounds by formula (I-c-2) may also be prepared by alkylating a compound of formula (I) wherein L is a radical of formula (b-2) wherein R⁵ is hydrogen, said compounds being represented by formula (I-c-3), with a reagent of formula (XIII). The compounds of formula (I-c-2) can also be prepared by alkylating a compound of formula (I-c-4) with a reagent of formula (XIV). The alkylation reactions of (XIII) with (I-c-3) and (XIV) with (I-c-4) may conveniently be conducted in an inert organic solvent such as, for example, an aromatic hydrocarbon, e.g., benzene, methylbenzene, dimethylbenzene; a ketone, e.g., 2-propanone, 4-methyl-2-pentanone; an ether, e.g., 1,4-dioxane, 1,1′-oxybisethane, tetrahydrofuran; and a polar aprotic solvent, e.g., N , N -dimethylformamide; N , N -dimethylacetamide; dimethyl sulfoxide; nitrobenzene and 1-methyl-2-pyrrolidinone. The addition of an appropriate base such as, for example, an alkali metal carbonate or hydrogen carbonate, sodium hydride or an organic base such as, for example, N , N -diethylethanamine or N -(1-methylethyl)-2-propanamine may be utilized to pick up the acid which is liberated during the course of the reaction. Somewhat elevated temperatures may enhance the rate of the reaction. The compounds of formula (I) wherein L is a radical of formula (b-3) wherein Z¹ is NH and Z² is other than a direct bond, said Z² being represented by Z 2-a , and said compounds by (I-c-5) can be prepared by reacting an isocyanate or isothiocyanate of formula (I-c-6) with a reagent of formula (XV). The compounds of formula (I) wherein L is a radical of formula (b-3) wherein Z² is NH and Z¹ is other than a direct bond, said Z¹ being represented by Z 1-a and said compounds by (I-c-7), can be prepared by reacting a isocyanate or isothiocyanate of formula (XVI) with a compound of formula (I-c-8). The reaction of (XV) with (I-c-6), or (XVI) with (I-c-8) is generally conducted in a suitable reaction-inert solvent such as, for example, an ether, e.g., tetrahydrofuran. Elevated temperatures may be suitable to enhance the rate of the reaction. The compounds of formula (I) wherein L is a radical of formula (b-3) wherein Z² is a direct bond and Z¹ is other than a direct bond, said compounds being represented by (I-c-9), can be prepared be reacting a reacting of formula (XVII) or a functional derivative thereof with a compound of formula (I-c-8). The reaction of (XVII) with (I-c-8) may generally be conducted following art-known esterification- or amidation reaction procedures. For example, the carboxylic acid may be converted into a reactive derivative, e.g., an anhydride or a carboxylic acid halide, which subsequently is reacted with (I-c-8); or by reacting (XVII) and (I-c-8) with a suitable reagent capable of forming amides or esters, e.g., N , N -methanetetraylbis[cyclohexamine] and 2-chloro-1-methylpyridinium iodide. Said reactions are most conveniently conducted in a suitable solvent such as, for example, an ether, e.g., tetrahydrofuran, a halogenated hydrocarbon, e.g., dichloromethane, trichloromethane or a polar aprotic solvent. The addition of a base such as, N , N -diethylethanamine may be appropriate. The compounds of formula (I) wherein L is a radical of formula L³-C₂₋₆alkanediyl, said L³ being Ar², Het, Ar²-sulfonyl or a radical of formula R⁶-Z²-C(=X)-, and said compounds being represented by formula (I-c-10), may also be prepared by reacting an appropriate alkenylene of formula (XVIII) with a compound of formula (I-d). The compounds of formula (I) wherein L is a radical of formula (b-4) or a 2-hydroxyethyl, said compounds being represented by formula (I-c-11), may also be prepared by reacting a reagent (XIX) with a compound of formula (I-d). R²⁵ in (XIX) and (I-c-11) being hydrogen or a radical R⁷-O-CH₂-. The reactions of (XVIII) with (I-d) and (XIX) with (I-d) may be conducted by stirring and, if desired, heating the reactants. The said reactions may be conducted in a suitable solvent such as, for example, a ketone, e.g., 2-propanone, 4-methyl-2-pentanone, an ether, e.g., tetrahydrofuran, 1,1′-oxybisethane, an alcohol, e.g., methanol, ethanol, 1-butanol, a polar aprotic solvent, e.g., N , N -dimethylformamide and N , N -dimethylacetamide. The compounds of formula (I) wherein R⁴, R⁵ or R⁶ are Het, may also be prepared following procedures for preparing ring systems which are known in the art or analogues procedures thereof. A number of such cyclization procedures are described in for example, the Published European Patent Publication No. 151,826, For example, compounds of formula (I-c-12) can be obtained by a cyclizing reaction of (I-c-13) following art-known cyclodesulfurization procedures. In (I-c-13) and (I-c-12) G⁵ and R²² have the same meanings as described hereinbefore. Compounds wherein Het is an optionally substituted imidazolyl radical, said compounds being represented by the formula (I-c-13), can be prepared by the cyclization reaction of an appropriate N -(2,2-dilower alkyloxyethyl)guanidine derivative of formula (XX). In (XX) and (I-c-14) R²⁶ is either hydrogen, C₁₋₆alkyl or Ar²-C₁₋₆alkyl. The compounds of formula (I) can also be converted into each other following art-known procedures of functional grouptransformation. Some examples of such procedures will be cited hereinafter. The compounds of formula (I) containing a cyano substituent can be converted into the corresponding amines by stirring and, if desired, heating the starting cyano compounds in a hydrogen containing medium in the presence of a suitable amount of an appropriate catalyst such as, for example, platinum-on-charcoal or Raney-nickel. Suitable solvents are, for example, methanol or ethanol. The hydrogen atoms of the amino function(s) of compounds of formula (I) may be substituted following art-known procedures such as, for example, N -alkylation, N -acylation or reductive N -alkylation. For example alkylcarbonyl or arylcarbonyl may be introduced by reacting the starting amine with an appropriate carboxylic acid or a derivative thereof such as, for example, an acid halide or acid anhydride. The compounds of formula (I) containing a substituted amine may be converted into the corresponding compounds of formula (I) wherein said nitrogen bears a hydrogen atom following art-known methods for preparing NH groups. For example, where said amine is substituted with a C₁₋₆alkyloxycarbonyl group by treating the starting material with an acid or a base in a suitable solvent. As suitable acids there may be cited hydrohalic acids, e.g., hydrochloric acid or hydrobromic acid, sulfuric or phosphoric acid preferably employed as an aqueous solution or mixed with, e.g., acetic acid. Suitable bases are the alkali metal hydroxides, hydrides or alkoxides in an aqueous or alcoholic medium. Or, where said nitrogen is substituted with an Ar²-CH₂ group, by treating the starting compounds with hydrogen in the presence of a suitable catalyst, e.g., palladium-on-charcoal, platinum-on-charcoal, preferably in an alcoholic medium. The compounds of formula (I) containing a nitrogen atom substituted with Ar²-CH₂- may also be converted into the corresponding compounds where said nitrogen is substituted with C₁₋₆alkyloxycarbonyl, for example by treating the former compounds with a C₁₋₆alkylcarbonohalidate, e.g., ethyl carbonochloridate in the presence of a suitable solvent, e.g., methylbenzene and, if desired, in the presence of an appropriate base. The compounds of formula (I) wherein the piperazine of hexahydro-1 H -1,4-diazepine nitrogen is substituted with a C₁₋₆alkyloxycarbonyl group may be converted into the corresponding compounds wherein the ring nitrogen is substituted with methyl by reducing the starting compounds with an appropriate reductant such as, lithium tetrahydroaluminate. The compounds of formula (I) containing an amino group may be converted into the corresponding isothiocyanato containing compounds by treating the starting amino compounds with CS₂ optionally in the presence of N , N -methanetetraylbis[cyclohexamine]. In all of the foregoing and in the following preparations, the reaction products may be isolated from the reaction mixture and, if necessary, further purified according to methodologies generally known in the art. Some intermediates and starting materials in the foregoing preparations are known compounds which may be prepared according to art-known methodologies of preparing said or similar compounds and others are new. A number of such preparation methods will be described hereinafter in more detail. Intermediates of formula (II-a) may be prepared by reacting a piperazine of hexahydro-1 H -1,4-diazepine derivative of formula (V) with an appropriately substituted nitro-pyridine or -pyrimidine of formula (XXI), thus preparing (XXII), and subsequently reducing the nitro function. Whereas the intermediates of formula (II-b) may be prepared by reacting a piperazine of hexahydro-1 H -1,4-diazepine derivative of formula (V) with an appropriately substituted diamine of formula (XXIII). The N -alkylation reactions of (V) with (XXI) and (V) with (XXIII) may be carried out following the N -alkylation procedures described for the preparation of (I) starting from (V) and (VI). The nitro-to-amine reduction reaction is generally carried out by stirring an intermediate of formula (XXI) in a hydrogen containing medium in the presence of a suitable amount of an appropriate catalyst such as, for example, platinium-on-charcoal, palladium-on-charcoal or Raney-nickel. Suitable solvents are, for example, an alcohol, e.g., methanol, ethanol, 2-propanol or 1-butanol. Intermediates of formula (VI) can be prepared by condensing an appropriately substituted pyridinediamine or pyrimidinediamine of formula (III) with a carbonic acid of formula (XXIV) or a suitable functional derivative thereof, preferably the imino ester form thereof, following the procedures for preparing (I) from (IV) and (III). The starting materials of formula (III) can be prepared by reacting a nitro-pyridine or -pyrimidine of formula (XXV) with an amide of formula (XXVI) and subsequently reducing the nitro function. The starting materials of formula (XXIII) and (XXI) can be prepared by reacting an appropriately substituted pyridinediamine or pyrimidinediamine of formula (III) or their corresponding nitro analogue of formula (XXVII) with a carbonic acid of formula (XXIV), preferably the halide form thereof. The intermediates of formula (V) wherein L is other than hydrogen, said compounds being represented by formula (V-a), can be prepared by N -alkylating a protected piperazine or hexahydro-1 H -1,4-diazepine of formula (XXVIII) with a reagent of formula L¹-W (XI), thus preparing an intermediate (XXIX), and subsequently removing the protected group P following art-known procedures, e.g. by hydrolysis in an acidic or an alkaline aqueous medium or by catalytic hydrogenation, depending upon the nature of P. In (XXVIII) P is an appropriate protected group such as, for example, C₁₋₆alkyloxycarbonyl, phenylmethoxycarbonyl or phenylmethyl From formula (I) it is evident that the compounds of this invention may have several asymmetric carbon atoms in their structure. Each of these chiral centers may be present in a R- and a S-configuration, this R- and S-notation being in correspondence with the rules described by R.S. Cahn, C. Ingold and V. Prelog in Angew. Chem., Int. Ed. Engl., 5 , 385, (1966). Pure stereochemically isomeric forms of the compounds of formula (I) may be obtained by the application of art-known procedures. Diastereoisomers may be separated by physical separation methods such as selective crystallization and chromatographic techniques, e.g., counter current distribution, and enantiomers may be separated from each other by the selective crystallization of their diastereomeric salts with optically active acids. Pure stereochemically isomeric forms may also be derived from the corresponding pure stereochemically isomeric forms of the appropriate starting materials, provided that the reaction occurs stereospecifically. It is evident that the cis and trans diastereomeric racemates may be further resolved into their optical isomers, cis(+), cis(-), trans(+) and trans(-) by the application of methodologies known to those skilled in the art. Stereochemically isomeric forms of the compounds of formula (I) are naturally intended to be embraced within the scope of the invention. The compounds of formula (I), the pharmaceutically acceptable acid addition salts and possible stereochemically isomeric forms thereof possess useful pharmacological properties. More particularly, they are active an anti-histaminics which activity can clearly be demonstrated by e.g., the results obtained in the "Protection of Rats from Compound 48/80-induced lethality"-test, the "Histamine antagonism in Guinea Pig"-test and the "Ascaris Allergy test in Dogs"-test described in Arch. Int. Pharmacodyn. Ther. 251, 39-51 (1981). Apart from their anti-histaminic properties some of the subject compounds also show serotonin-antagonism. Furthermore the compounds of formula (I), the pharmaceutically acceptable acid addition salts and stereochemically isomeric forms thereof are particularly attractive due to their favourable pharmacokinetical profile and high selectivity. In particularly, they show a rapid onset so that their anti-histaminic effects are almost instantaneously present. In view of their anti-histaminic properties, the compounds of formula (I) and their acid addition salts are very useful in the treatment of allergic diseases such as, for example, allergic rhinitis, allergic conjunctivities, chronic urticaria, or allergic asthma. In view of their useful pharmacological properties the subject compounds may be formulated into various pharmaceutical forms for administration purposes. To prepare the pharmaceutical compositions of this invention, an effective amount of the particular compound, in base or acid addition salt form, as the active ingredient is combined in intimate admixture with a pharmaceutically acceptable carrier, which carrier may take a wide variety of forms depending on the form of preparation desired for administration. These pharmaceutical compositions are desirably in unitary dosage form suitable, preferably, for administration orally, rectally, percutaneously, or by parenteral injection. For example, in preparing the compositions in oral dosage form, any of the usual pharmaceutical media may be employed such as, for example, water, glycols, oils or alcohols in the case of oral liquid preparations such as suspensions, syrups, elixirs and solutions: or solid carriers such as starches, sugars, kaolin, lubricants, binders or disintegrating agents in the case of powders, pills, capsules and tablets. Because of their ease in administration, tablets and capsules represent the most advantageous oral dosage unit form, in which case solid pharmaceutical carriers are obviously employed. For parental compositions, the carrier will usually comprise sterile water, at least in large part, though other ingredients, for example, to aid solubility, may be included. Injectable solutions, for example, may be prepared in which the carrier comprises saline solution, glucose solution or a mixture of saline and glucose solution. Injectable suspensions may also be prepared in which case appropriate liquid carriers, suspending agents may be employed. In the compositions suitable for percutaneous administration, the carrier optionally comprises a penetration enhancing agent and/or a suitable wetting agent, optionally combined with suitable additives of any nature in minor proportions, which additives do not introduce a significant deletorious effect on the skin. Said additives may facilitate the administration to the skin and/or may be helpful for preparing the desired compositions. These compositions may be administered in various ways, e.g., as a transdermal patch, as a spot-on, as an ointment. Acid addition salts of (I) due to their increased water solubility over the corresponding base form, are obviously more suitable in the preparation of aqueous compositions. It is especially advantageous to formulate the aforementioned pharmaceutical compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used in the specification and claims herein refers to physically discrete units suitable as unitary dosages, each unit containing a predetermined quantity of active ingredient calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. Examples of such dosage unit forms are tablets (including scored or coated tablets), capsules, pills, powder packets, wafers, injectable solutions or suspensions, teaspoonfuls or tablespoonfuls, and segregated multiples thereof. Those of skill in treating allergic diseases in warm-blooded animals could easily determine the effective amount from the test results presented hereinafter. In general it is contemplated that an effective amount would be from 0.001 mg/kg to 100 mg/kg body weight, and more preferably from 0.01 mg/kg to 1 mg/kg body weight. The following examples are intended to illustrate and not to limit the scope of the present invention in all its aspects. Unless otherwise stated all parts therein are by weight. Experimental part A. Intermediates Example 1 a) To a stirred solution of 42.24 parts of N -(2-ethoxyethyl)-3-nitro-2-pyridinamine in 309 parts of 1,4-dioxane were added 49.7 parts of 2-chloroacetyl chloride. The reaction mixture was stirred for 4 hours at reflux temperature. The whole was evaporated and the residue was taken up in methylbenzene. The organic layer was evaporated again, yielding 57.5 parts (100%) of 2-chloro- N -(2-ethoxyethyl)- N -(3-nitro-2-pyridinyl)acetamide as a residue (int. 1). b) A solution of 19.3 parts of 2-chloro- N -(2-ethoxyethyl)- N -(3-nitro-2-pyridinyl)acetamide, 11.4 parts of ethyl 1-piperazinecarboxylate and 7.63 parts of sodium carbonate in 270 parts of methylbenzene was stirred for 18 hours at 80°C. The reaction mixture was evaporated and the residue was taken up in water and dichloromethane. The organic layer was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (99:1 by volume) as eluent. The pure fractions were collected and the eluent was evaporated, yielding 16.7 parts (60.9%) of ethyl 4-[2-[(2-ethoxyethyl) (3-nitro-2-pyridinyl)amino]-2-oxomethyl]-1-piperazinecarboxylate as a residue (int. 2). In a similar manner there were also prepared : Example 2 A mixture of ethyl 4-[2-[(2-ethoxyethyl) (3-nitro-2-pyridinyl)amino]-2-oxomethyl]-1-piperazinecarboxylate, 2 parts of a solution of thiophene in methanol 4% and 200 parts of methanol was hydrogenated at normal pressure and at room temperature with 3 parts of palladium-on-charcoal catalyst 10%. After the calculated amount of hydrogen was taken up, the catalyst was filtered off and the filtrate was evaporated, yielding 15.2 parts (100%) of ethyl 4-[2-[(3-amino-2-pyridinyl) (2-ethoxyethyl)amino]-2-oxomethyl]-1-piperazinecarboxylate as a residue (int. 14). In a similar manner there were also prepared : Example 3 a) To a stirred solution of 3.8 parts of N³-(2-ethoxyethyl)-2,3-pyridinediamine in 50 parts of 1,4-dioxane were added 5.64 parts of 2-chloroacetyl chloride. The reaction mixture was stirred for 5 hours at reflux temperature. The reaction mixture was evaporated and the residue was dissolved in methylbenzene. The whole was evaporated again, yielding 3.62 parts (70.4%) of 2-chloro- N -[3-[(2-ethoxyethyl)amino]-2-pyridinyl]acetamide as a residue (int. 24). b) A mixture of 3.62 parts of 2-chloro- N -[3-[(2-ethoxyethyl)amino]-2-pyridinyl]acetamide, 10.6 parts of 1-(phenylmethyl)piperazine, 6.4 parts of sodium carbonate and 90 parts of methylbenzene was stirred for 20 hours at 80°C. The reaction mixture was evaporated and the residue was taken up in water. The product was extracted with dichloromethane. The extract was dried, filtered and evaporated, yielding 7.9 parts (100%) of N -[3-[(2-ethoxyethyl)amino]-2-pyridinyl]-4-(phenylmethyl)-1-piperazineacetamide as a residue (int. 25). In a similar manner there was also prepared : N -[3-[(2-ethoxyethyl)amino]-4-pyridinyl]-4-(phenylmethyl)-1-piperazineacetamide as a residue (int. 26). Example 4 a) To a stirred solution of 25.4 parts of 2-chloro-3-nitropyridine, 29.5 parts of 2-pyrazinemethanamine dihydrochloride and 235 parts of N , N -dimethylacetamide were added 67.8 parts of sodium carbonate. The reaction mixture was stirred for 1.5 hours at 100°C. The reaction mixture was poured into water and 4-methyl-2-pentanone. The whole was filtered twice over diatomaceous earth and the layers were separated. The organic layer was dried, filtered and evaporated. The residue was crystallized from acetonitrile. The product was filtered off and dried, yielding 3.6 parts (10%) of N -(3-nitro-2-pyridinyl)-2-pyrazinemethanamine (int. 27). b) A mixture of 3.55 parts of N -(3-nitro-2-pyridinyl)-2-pyrazinemethanamine, 2 parts of a solution of thiophene in methanol 4% and 120 parts of methanol was hydrogenated at normal pressure and at room temperature with 2 parts of platinum-on-charcoal catalyst 5%. After the calculated amount of hydrogen was taken up, the catalyst was filtered off and the filtrate was evaporated to dry, yielding 3.6 parts (100%) of N -(2-pyrazinylmethyl)-1,2-pyridinediamine as a residue (int. 28). c) To a stirred solution of 3.6 parts of N -(2-pyrazinylmethyl)-1,2-pyridinediamine in 30 parts of acetic acid were added 4.24 parts of ethyl 2-chloroethanimidate monohydrochloride. The reaction mixture was stirred first for 21 hours at room temperature and then for a few minutes at 90°C. The whole was evaporated and the residue was taken up in water. The aqueous layer was treated with sodium carbonate and the product was extracted with dichloromethane. The extract was dried, filtered and evaporated, yielding 3.9 parts (100%) of 2-(chloromethyl)-3-(2-pyrazinylmethyl)-3 H -imidazo [4,5-b]-pyridine as a residue (int. 29). In a similar manner there were also prepared : 8-(chloromethyl)-9-(2-ethoxyethyl)-9 H -purine as a residue (int. 30); and 2-(chloromethyl)-3 H -imidazo[4,5-b]pyridine-3-ethanol; mp. 136.2°C (int. 31). B. Final compounds Example 5 A mixture of 10.6 parts of N -(3-amino-2-pyridinyl)- N -(2-furanylmethyl)-4-methyl-1-piperazineacetamide, 0.1 parts of 4-methylbenzenesulfonic acid and 95 parts of dimethylbenzene was stirred for 40 hours at reflux temperature using a water separator. The reaction mixture was evaporated and the residue was taken up in dichloromethane and a diluted sodium hydroxide solution. The separated organic layer was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol, saturated with ammonia (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The salt was filtered off and dried, yielding 4.34 parts (26.6%) of 3-(2-furanylmethyl)-2-[(4-methyl-1-piperazinyl)methyl]-3 H -imidazo-[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 124.5°C (compound 1). In a similar manner there were also prepared : ethyl 4-[[3-[(5-methyl-2-furanyl)methyl]-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinecarboxylate as a residue (compound 2); 2-[(4-methyl-1-piperazinyl)methyl]-3-(4-thiazolylmethyl)-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:1); mp. 175.9°C (compound 3); 3-(2-ethoxyethyl)-2-[(hexahydro-4-methyl-1 H -1,4-diazepin-1-yl)-methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 153.4°C (compound 4); 2-[(4-methyl-1-piperazinyl)methyl]-3-[2-(phenylmethoxy)ethyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 162.6°C (compound 5); ethyl 4-[[1-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinecarboxylate as a residue (compound 6); 3-(2-ethoxyethyl)-2-[[hexahydro-4-(phenylmethyl)-1 H -1,4-diazepin-1-yl]-methyl]-3 H -imidazo[4,5-b]pyridine ethanedioate(1:2); mp. 136°C (compound 7); 3-[(3-methyl-2-furanyl)methyl]-2-[(4-methyl-1-piperazinyl)methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 186.5°C (compound 8); ethyl 4-[[3-(3-methyl-2-furanyl)methyl]-3 H -imidazo[4,5-b]pyridin2-yl]methyl]-1-piperazinecarboxylate as a residue (compound 9); and ethyl 4-[2-[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]ethyl]-1-piperazinecarboxylate as a residue (compound 10). Example 6 A mixture of 37.8 parts of N -[3-[(2-ethoxyethyl)amino]-4-pyridinyl]-4-(phenylmethyl)-1-piperazineacetamide, 0.1 parts of 4-methylbenzenesulfonic acid and 450 parts of dimethylbenzene was stirred for 16 hours at reflux temperature using a water separator. The reaction mixture was evaporated and the residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (93:7 by volume) as eluent. The pure fractions were collected and the eluent was evaporated, yielding 20.2 parts (56.1%) of 3-(2-ethoxyethyl)-2-[[4-(phenylmethyl)-1-piperazinyl]methyl]-3 H -imidazo[4,5-c]pyridine as a residue (compound 11). In a similar manner there was also prepared : 1-(2-ethoxyethyl)-2-[[4-(phenylmethyl)-1-piperazinyl]methyl]-1H-imidazo[4,5-b]pyridine as a residue (compound 12); and 2-[(4-cyclohexyl-1-piperazinyl)methyl]-3-(2-ethoxyethyl)-3 H -imidazo-[4,5-b]pyridine (E)-2-butenedioate(2:3); mp. 190.6°C (compound 13). Example 7 A mixture of 8.5 parts of 4-methyl- N -[(5-methyl-2-furanyl)methyl]- N -(3-nitro-2-pyridinyl)-1-piperazineacetamide, 2 parts of a solution of thiophene in methanol 4% and 200 parts of methanol was hydrogenated at normal pressure and at room temperature with 2 parts of platinum-on-charcoal catalyst 5%. After the calculated amount of hydrogen was taken up, the catalyst was filtered off and the filtrate was evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was further purified by column chromatography (HPLC) over silica gel using a mixture of dichloromethane, hexane, methanol and methanol, saturated with ammonia (50:45:5:0.5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The salt was filtered off and dried, yielding 3.49 parts (26.7%) of 3-[(5-methyl-2-furanyl)methyl]-2-[(4-methyl-1-piperazinyl)methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2) (compound 14). In a similar manner there were also prepared : 3-(2-ethoxyethyl)-2-[3-[4-(phenylmethyl)-1-piperazinyl]propyl-3 H -imidazo[4,5-b]pyridine as a residue (compound 15); and 3-(2-ethoxyethyl)-2-[4-(1-piperazinyl)butyl]-3 H -imidazo[4,5-b]-pyridine (E)-2-butenedioate(1:2) ; mp. 148.2°C (compound 16). Example 8 A mixture of 3.35 parts of 2-(chloroethyl)-3-(2-ethoxyethyl)-3 H -imidazo[4,5-a]pyridine monohydrochloride and 6 parts of 1-methylpiperazine was stirred for 1 hour at 100°C. The reaction mixture was evaporated and the residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol, saturated with ammonia, (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was taken up in 2,2′-oxybispropane and activated charcoal. The whole was filtered over diatomaceous earth and the filtrate was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The salt was filtered off and crystallized from 2-propanol. The product was filtered off and dried, yielding 2.24 parts (44.4%) of 3-(2-ethoxyethyl)-2-[(4-methyl-1-piperazinyl)methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:1); mp. 165.8°C (compound 17). Example 9 To a stirred mixture of 13.5 parts of ethyl 1-piperazinecarboxylate and 160 parts of ethanol were added 18 parts of 2-(chloromethyl)-3 H -imidazo[4,5-b]pyridine-3-ethanol. After the addition of 10.6 parts of sodium carbonate, the reaction mixture was stirred for 32 hours at reflux temperature. The whole was evaporated and the residue taken up in water. The product was extracted with dichloromethane. The extract was washed with water, dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was crystallized from 2,2′-oxybispropane. The product was filtered off and dried, yielding 17.5 parts (62.7%) of ethyl 4-[[3-(2-hydroxyethyl)-3 H -imidazo-[4,5-b]pyridin-2-yl]methyl]-1-piperazinecarboxylate; mp. 117.4°C (compound 18). In a similar manner there were also prepared : 3-(2-ethoxyethyl)-2-[[2-methyl-4-(phenylmethyl)-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine; mp. 91.2°C (compound 19); ethyl 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-2-methyl-1-piperazinecarboxylate ethanedioate(1:1) ; mp. 146.6°C (compound 20); 3-(2-ethoxyethyl)-2-[[4-[[3-[(5-methyl-2-furanyl)methyl]-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 200.1°C (compound 21); and 2-[(4-methyl-1-piperazinyl)methyl]-3-(2-pyrazinylmethyl)-3 H -imidazo[4,5-b]pyridine; mp. 119.9°C (compound 22). Example 10 A mixture of 4.4 parts of 1-(phenylmethyl)piperazine, 4.7 parts of 8-(chloromethyl)-9-(2-ethoxyethyl)-9 H -purine, 2.1 parts of sodium hydrogen carbonate and 40 parts of ethanol was stirred and refluxed for 5 hours. The reaction mixture was evaporated and the residue was taken up in water. The product was extracted with trichloromethane. The extract was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (97:3 by volume) as eluent. The pure fractions were collected and the eluent was evaporated, yielding 4.6 parts (62.0%) of 9-(2-ethoxyethyl)-8-[[4-(phenylmethyl)-1-piperazinyl]methyl]9H-purine as a residue (compound 23). Example 11 A mixture of 3.3 parts of 3-(2-ethoxyethyl)-2-[4-(1-piperazinyl)butyl]-3 H -imidazo[4,5-b]pyridine, 2.9 parts of 2-(chloromethyl)-3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridine, 1.2 parts of sodium carbonate and 22.5 parts of N , N -dimethylacetamide was stirred for 6 hours at 70°C. The reaction mixture was evaporated and the residue was extracted with dichloromethane. The extract was dried, filtered and evaporated. The residue was converted into the ethanedioate salt in 2-propanol. The salt was filtered off and crystallized from 2-propanol. The product was filtered off and dried, yielding 0.7 parts (6.8%) of 3-(2-ethoxyethyl)-2-[[4-[4-[3-(2-ethoxyethyl)-3 H -imidazo-4,5-b]pyridin-2-yl]butyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine ethanedioate(1:6); mp. 121.9°C (compound 24). Example 12 To a stirred solution of 8 parts of ethyl 4-[[3-[(5-methyl-2-furanyl)methyl]-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinecarboxylate in 84 parts of 2-propanol were added 11.8 parts of potassium hydroxide. After stirring for 3 hours at reflux temperature, the reaction mixture was allowed to stand overnight at room temperature. The mixture was evaporated and the residue was taken up in water. The product was extracted with dichloromethane. The extract was washed with water, dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol, saturated with ammonia, (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The salt was filtered off and dried, yielding 4.61 parts (40.3%) of 3-[(5-methyl-2-furanyl)methyl]-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 187.0°C (compound 25). In a similar manner there were also prepared : 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:1); mp. 183.3°C (compound 26); 3-[(3-methyl-2-furanyl)methyl]-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:1); mp. 170.9°C (compound 27); 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine; mp. 108.2°C (compound 28); 3-(2-ethoxyethyl)-2-[2-(1-piperazinyl)ethyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2) monohydrate; mp. 166.1°C (compound 29); and 3-(2-ethoxyethyl)-2-[(3-methyl-1-piperazinyl)methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(2:3); mp. 159.9°C (compound 30). Example 13 A mixture of 8.3 parts of 1-(2-ethoxyethyl)-2-[[4-(phenylmethyl)-1-piperazinyl]methyl]-1 H -imidazo[4,5-b]pyridine and 200 parts of methanol was hydrogenated at normal pressure and at room temperature with 2 parts of palladium-on-charcoal catalyst 10%. After the calculated amount of hydrogen was taken up, the catalyst was filtered off and the filtrate was evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol, saturated with ammonia, (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated, yielding 3.2 parts (46.1%) of 1-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-1 H -imidazo[4,5-b]pyridine as a residue (compound 31). In a similar manner there were also prepared : 3-(2-ethoxyethyl)-2-[(hexahydro-1H-1,4-diazepin-1-yl)methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate (1:2) 2-propanolate (2:1); mp. 145.5°C (compound 32); 3-(2-ethoxyethyl)-2-[3-(1-piperazinyl)propyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 160.7°C (compound 33); 3-(2-ethoxyethyl)-2-[(2-methyl-1-piperazinyl)methyl]-3 H -imidazo[4,5-b]piperidine (E)-2-butenedioate(2:3); mp. 169.6°C (compound 34); 9-(2-ethoxyethyl)-8-(1-piperazinylmethyl)-9 H -purine (E)-2-butenedioate(2:3); mp. 170.4°C (compound 35); 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-c]pyridine (E)-2-butenedioate(2:3); mp. 200.5°C (compound 36); and 1-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-1 H -imidazo[4,5-c]pyridine (E)-2-butenedioate(2:3); mp. 169.7°C (compound 37). Example 14 A mixture of 2.7 parts of 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-c]pyridine, 2.7 parts of 1-(2-bromoethyl)-4-ethyl-1,4-dihydro-5 H -tetrazol-5-one, 1.3 parts of sodium carbonate and 72 parts of N , N -dimethylacetamide was stirred overnight at 70°C. The reaction mixture was poured into water and the product was extracted with dichloromethane. The extract was dried, filtered and evaporated. The residue was converted into the ethanedioate salt in 2-propanol. The salt was filtered off and dried, yielding 3.9 parts (64.0%) of 1-[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl)]-4-ethyl-1,4-dihydro-5 H -tetrazol-5- one ethanedioate(1:2); mp. 170.9°C (compound 38). In a similar manner there were also prepared : Example 15 A mixture of 2.5 parts of 5-(2-chloroethyl)-4-methylthiazole, 2.8 parts of 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine, 1.5 parts of N , N -diethylethanamine and 80 parts of N , N -dimethylacetamide was stirred over weekend at 70°C. The reaction mixture was evaporated and the residue was taken up in water. The product was extracted with dichloromethane. The extract was washed with a sodium carbonate solution, dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (97:3 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the ethanedioate salt in 2-propanol. The product was filtered off and dried, yielding 0.9 parts (15.1%) of 3-(2-ethoxyethyl-2-[[4-[2-(4-methyl-5-thiazolyl)ethyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine ethanedioate(1:2); mp. 189.5°C (compound 74). Example 16 A mixture of 5.3 parts of chloroacetonitrile, 14.4 parts of 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine, 7.4 parts of sodium carbonate and 288 parts of N , N -dimethylformamide was stirred overnight at room temperature. The reaction mixture was stirred into water and the product was extracted with dichloromethane. The extract was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was stirred in 2,2′-oxybispropane. The product was filtered off and dried, yielding 13 parts (79.2%) of 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineacetonitrile; mp. 80.7°C (compound 75). In a similar manner there were also prepared : 3-[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]-2-methyl-4 H -pyrido[1,2-a]pyrimidin-4-one (E)-2-butenedioate(1:1) 2-propanolate(2:1); mp. 187.8°C (compound 76); 1-[3-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]propyl]-1,3-dihydro-2 H -benzimidazol-2-one ethanedioate(1:2); mp. 217.6°C (compound 77); 4-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]-1-(4-fluorophenyl)-1-butanone ethanedioate(1:2); mp. 152.4°C (compound 78); 3-(2-ethoxyethyl)-2-[[4-[3-(4-fluorophenoxy)propyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine ethanedioate(1:2); mp. 160.5°C (compound 79); and ethyl 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineacetate ethanedioate(1:2); mp. 166.8°C (compound 80). Example 17 A mixture of 2.7 parts of 6-(2-chloroethyl)-1,7-dimethyl-1 H ,5 H -imidazo[1,2-a]pyrimidin-5-one, 2.9 parts of 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine, 1.06 parts of sodium carbonate and 80 parts of 4-methyl-2-pentanone was stirred first for 44 hours at reflux temperature and then over weekend at room temperature. The reaction mixture was evaporated and the residue was taken up in water. The product was extracted with dichloromethane. The extract was washed with water, dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The salt was filtered off and dried, yielding 3.36 parts (47.3%) of 6-[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]-pyridin-2-yl]methyl]1-piperazinyl]ethyl]-1,7-dimethyl-1 H ,5 H -imidazo[1,2-a]pyrimidin-5-one (E)-2-butenedioate(1:2); mp. 162.5°C (compound 81). In a similar manner there were also prepared : Example 18 A mixture of 1.4 parts of 3-bromo-1-propene, 2.8 parts of 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine, 1.26 parts of sodium hydrogen carbonate and 64 parts of ethanol was stirred for 4 hours at reflux temperature. The reaction mixture was filtered over diatomaceous earth and the filtrate was evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (93:7 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The salt was filtered off and dried, yielding 2 parts (39.7%) of 3-(2-ethoxyethyl)-2-[[4-(2-propenyl)-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(2:3); mp. 175.3°C (compound 92). In a similar manner there were also prepared : 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]- N -(1-methylethyl)-1-piperazinepropanamide (E)-2-butenedioate(2:5); mp. 169.8°C (compound 93); 3-(2-ethoxyethyl)-2-[[4-[2-(phenylsulfonyl)ethyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 164.2°C (compound 94); and 2,2′-[(1,4-piperazinediyl)bismethyl]bis[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 219.1°C (compound 95). Example 19 A mixture of 4.15 parts of 2,4-dimethoxybenzaldehyde, 2.8 parts of 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine, 2 parts of a solution of thiophene in methanol and 120 parts of methanol was hydrogenated at normal pressure and at room temperature with 2 parts of palladium-on-charcoal catalyst 10%. After the calculated amount of hydrogen was taken up, the catalyst was filtered off and the filtrate was evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the ethanedioate salt in 2-propanol. The product was filtered off and dried, yielding 4.38 parts (70.7%) of 2-[[4-[(2,4-dimethoxyphenyl)methyl]-1-piperazinyl]methyl]-3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridine ethanedioate(1:2); mp. 173.4°C (compound 96). In a similar manner there were also prepared : 3-(2-ethoxyethyl)-2-[4-(4-methyl-1-piperazinyl)butyl]-3 H -imidazo-[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 186.0°C (compound 97); 3-(2-ethoxyethyl)-2-[3-(4-methyl-1-piperazinyl)-propyl]-3 H -imidazo-[4,5-b]pyridine (E)-2-butenedioate(1:3); mp. 183.7°C (compound 98); 3-(2-ethoxyethyl)-2-[[4-(1-methylethyl)-1-piperazinyl]methyl]-3 H -imidazo-[4,5-b]pyridine ethanedioate(1:2); mp. 167.7°C (compound 99); 2-[(2,4-dimethyl-1-piperazinyl)methyl]-3-(2-ethoxyethyl)-3 H -imidazo-[4,5-b]pyridine (E)-2-butenedioate(2:3); mp. 155.5°C (compound 100); 2-[(3,4-dimethyl-1-piperazinyl)methyl]-3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(2:3); mp. 157.1°C (compound 101); 3-(2-ethoxyethyl)-2-[(4-ethyl-1-piperazinyl)methyl]-3 H -imidazo-[4,5-b]pyridine (E)-2-butenedioate(2:3); mp. 185.0°C (compound 102); 3-(2-ethoxyethyl)-2-[[4-[(3,4,5-trimethoxyphenyl)methyl-1-piperazinyl]methyl]-3 H -imidazo-[4,5-b]pyridine ethanedioate(1:2); mp. 183.1°C (compound 103); and 9-(2-ethoxyethyl)-8-[(4-methyl-1-piperazinyl])methyl]-9 H -purine; mp. 69.7°C (compound 104). Example 20 A mixture of 1.26 parts of 2-chloropyrimidine, 3.6 parts of 4-[[3-(2-ethoxyethyl)-3H-imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineethanamine, 1.1 parts of sodium hydrogen carbonate and 64 parts of ethanol was stirred overnight at reflux temperature. The reaction mixture was evaporated and the residue was taken up in water. The product was extracted with dichloromethane. The extract was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (93:7 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the ethanedioate salt in 2-propanol. The product was filtered off and dried, yielding 3.8 parts (64.3%) of N -[2-[-4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]-2-pyrimidinamine ethanedioate(1:2); mp. 175.3°C (compound 105). In a similar manner there is also prepared : N -[2-[-4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]-5-methyl-1,3,4-thiadiazol-2-amine (compound 106). Example 21 To a stirred mixture of 5.2 parts of 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineethanol and 94 parts of N , N -dimethylformamide were added portionwise 0.82 parts of a sodium hydride dispersion 50% under nitrogen atmosphere. After cooling, 1.95 parts of 2-chloropyrimidine were added and the mixture was stirred overnight at room temperature. The reaction mixture was evaporated and the residue was taken up in water. The product was extracted with dichloromethane. The extract was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The product was filtered off and dried, yielding 5.42 parts (54.0%) of 3-(2-ethoxyethyl)-2-[[4-[2-(2-pyrimidinyloxy)ethyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butendioate(1:2); mp. 155.3°C (compound 107). In a similar manner there are also prepared : 3-(2-ethoxyethyl)-2-[[4-[2-[(thiazolo[5,4-b]pyridin-2-yl)thio]ethyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine (compound 108); and 3-(2-ethoxyethyl)-2-[[4-[2-[(thiazolo[5,4-b]pyridin-2-yl)oxy]ethyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 169.7°C (compound 109). Example 22 To a stirred mixture of 1.12 parts of 3-furancarboxylic acid, 2 parts of N , N -diethylethanamine and 195 parts of dichloromethane were added 2.6 parts of 2-chloro-1-methylpyridinium iodide. After stirring for 1 hour at room temperature, 3.6 parts of 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineethanamine and the mixture was stirred for 6 hours at room temperature. The reaction mixture was poured into water and the layers were separated. The organic layer was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol, saturated with ammonia (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the ethanedioate salt in 2-propanol. The salt was filtered off and crystallized from acetonitrile. The product was filtered off and dried, yielding 2.4 parts (39.6%) of N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl-3-furancarboxamide ethanedioate(1:2); 132.2°C (compound 110). In a similar manner there were also prepared : N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]-1-methyl-1H-pyrrole-2-carboxamide; mp. 132.6°C (compound 111); N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]-4-nitrobenzamide; mp. 180.7C°C (compound 112); and N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]-1-methyl-1 H -indole-2-carboxamide ethanedioate(1:2); mp. 177.0°C (compound 113). In a similar manner there are also prepared : 2-amino N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]benzamide (compound 114); and 3-amino- N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]-2-pyrazinecarboxamide (compound 115). Example 23 A mixture of 0.7 parts of isocyanatoethane, 3.6 parts 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazine ethanamine and 135 parts of tetrahydrofuran was stirred over weekend at room temperature. The reaction mixture was evaporated and the residue was taken up in dichloromethane. The extract was washed with water, dried, filtered and evaporated. The residue was converted into the ethanedioate salt in 2-propanol. The product was filtered off and dried, yielding 2.2 parts (35.8%) of N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]- N ′-methylurea ethanedioate(2:5); mp. 144.5°C (compound 116). In a similar manner there was also prepared : N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]- N ′-methylthiourea ethanedioate(1:2); mp. 119.7°C (compound 117). Example 24 A mixture of 1.65 parts of 2-(phenoxymethyl)oxirane, 8.9 parts of 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine and 40 parts of 2-propanol was stirred for 20 hours at reflux temperature. The reaction mixture was evaporated and the residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was crystallized from 2,2′-oxybispropane. The product was filtered off and dried, yielding 1.36 parts (31.0%) of 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-α-(phenoxymethyl)-1-piperazineethanol; mp. 102.5°C (compound 118). In a similar manner there were also prepared : 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineethanol ethanedioate(1:2); mp. 152.0°C (compound 119). Example 25 A mixture of 2.7 parts of 3-(2-ethoxyethyl)-2-(1-piperazinylmethyl)-3 H -imidazo[4,5-b]pyridine, 3 parts of 2-ethenylpyridine and 80 parts of 1-butanol was stirred overnight at 125°C. The reaction mixture was evaporated and the residue was poured into water. The product was extracted with dichloromethane. The extract was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The salt was filtered off and dried, yielding 3.3 parts (48.2%) of 3-(2-ethoxyethyl)-2-[[4-[2-(2-pyridinyl)ethyl]-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(2:5); mp. 162.1°C (compound 120). Example 26 a) To a stirred and cooled (-10°C) mixture of 18 parts of carbon disulfide, 7.22 parts of N , N ′-methanetetraylbis[cyclohexanamine] and 135 parts of tetrahydrofuran was added dropwise a solution of 12.9 parts of 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineethanamine in tetrahydrofuran. Upon complete addition, the temperature was allowed to reach room temperature. After stirring for 1 hour at room temperature, the mixture was evaporated, yielding 13.1 parts (100%) of 3-(2-ethoxyethyl)-2-[[4-(2-isothiocyanatoethyl)-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]pyridine as a residue (compound 121) b) A mixture of 3.8 parts of 3,4-pyridinediamine, 13.1 parts of 3-(2-ethoxyethyl)-2-[[4-(2-isothiocyanatoethyl)-1-piperazinyl]methyl]-3 H -imidazo[4,5-b]-pyridine and 135 parts of tetrahydrofuran was stirred overnight at reflux temperature. The whole was evaporated, yielding 16.9 parts (100%) of N -(4-amino-3-pyridinyl)- N ′-[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]thiourea as a residue (compound 122). c) A mixture of 16.9 parts of N -(4-amino-3-pyridinyl)- N ′-[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]thiourea, 11.4 parts of mercury(II)oxide, 0.1 parts of sulfur and 135 parts of tetrahydrofuran was stirred for 3 hours at reflux temperature. The reaction mixture was filtered while hot over diatomaceous earth and the filtrate was evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol, saturated with ammonia, (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was stirred in 2,2′-oxybispropane. The product was filtered off and dried, yielding 4.73 parts (30.0%) of N -[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]-1 H -imidazo[4,5-c]pyridin-2-amine; mp. 124.5°C (compound 123). Example 27 A mixture of 14 parts of N -(2,2-dimethoxyethyl)- N ′-[2-[4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazinyl]ethyl]guanidine monohydroiodide and 140 parts of a hydrochloric acid solution 1 N was stirred for 48 hours at room temperature. The mixture was treated with a sodium hydroxide solution and the product was extracted with dichloromethane. The extract was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol, saturated with ammonia (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was refluxed with methylbenzene and 4-methylbenzenesulfonic acid. The whole was evaporated and the residue was taken up in water and dichloromethane. The mixture was treated with a sodium hydroxide solution and the layers were separated. The organic layer was dried, filtered and evaporated. The residue was further purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (90:10 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was converted into the ethanedioate salt in 2-propanol. The salt was filtered off and dried, yielding 0.65 parts (3.7%) of 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]- N -(1 H -imidazol-2-yl)-1-piperazineethanamine ethanedioate(1:2); mp. 170.5°C (compound 124). Example 28 To a stirred solution of 2.5 parts of 2-[(4-methyl-1-piperazinyl)-methyl]-3 H -imidazo[4,5-b]pyridine-3-ethanol in 22.5 parts of N , N -dimethylformamide were added portionwise 0.48 parts of a sodium hydride dispersion 50%. Upon complete addition, stirring was continued first for 1 hour at room temperature and then for 1 hour at 30°C. After cooling, 0.723 parts of 3-chloro-1-propenyl were added (exothermic reaction). The reaction mixture was stirred for 3 hours at room temperature. The whole was poured into water and the product was extracted three times with methylbenzene and twice with dichloromethane. The combined extracts were dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was crystallized from 2,2′ oxybispropane. The product was filtered off and dried, yielding 1.42 parts (50.3%) of 2-[(4-methyl-1-piperazinyl)methyl]-3-[2-(2-propynyloxy)ethyl]-3 H -imidazo[4,5-b]pyridine; mp. 117.3°C (compound 125). In a similar manner there was also prepared : 2-[(4-methyl-1-piperazinyl)methyl]-3-[2-(2-propenyloxy)ethyl]-3 H -imidazo[4,5-b]pyridine (E)-2-butenedioate(1:2); mp. 159.0°C (compound 126). Example 29 A mixture of 6.3 parts of ethyl 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineacetamide, 17 parts of a sodium hydroxide solution 1 N, 150 parts of water and 16 parts of ethanol was stirred overnight at room temperature. The reaction mixture was evaporated and the residue was taken up in water. The aqueous layer was washed with dichloromethane and a small amount of a hydrochloric acid solution 1 N was added. The aqueous layer was evaporated and the residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol, saturated with ammonia (75:25 by volume) as eluent. The second fraction was collected and the eluent was evaporated. The residue was stirred in 2-propanone. The precipitate was filtered off and the filtrate was acidified with a hydrochloric acid solution. The precipitated product was filtered off and dried in vacuo, yielding 0.8 parts (10.3%) of 4-[[3-(2-ethoxyethyl)-3 H -imidazo-[4,5-b]pyridin-2-yl]methyl-1-piperazineacetic acid trihydrochloride; mp. 181.4°C (compound 127). Example 30 A mixture of 41.8 parts of 4-[[3-(2-ethoxyethyl)-3 H -imidazo-[4,5-b]pyridin-2-yl]methyl]-1-piperazineacetonitrile and 1100 parts of methanol, saturated with ammonia was hydrogenated at normal pressure and at room temperature with 20 parts of Raney nickel catalyst. After the calculated amount of hydrogen was taken up, the catalyst was filtered off and the filtrate was evaporated. The residue was converted into the (E)-2-butenedioate salt in 2-propanol. The salt was filtered off and crystallized from a mixture of acetonitrile and 2-propanol. The product was filtered off and dried, yielding 37.4 parts (52.1%) of 4-[[3-(2-ethoxyethyl)-3 H -imidazo[4,5-b]pyridin-2-yl]methyl]-1-piperazineethanamine; mp. 159.8°C (compound 128). Example 31 A mixture of 16.7 parts of 2-[(4-methyl-1-piperazinyl)methyl]-3-[2-(phenylmethoxy)ethyl]-3 H -imidazo[4,5-b]pyridine and 200 parts of methanol was hydrogenated at normal pressure and at room temperature with 3 parts of palladium-on-charcoal catalyst 10%. After the calculated amount of hydrogen was taken up, the catalyst was filtered off and the filtrate was evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol, saturated with ammonia, (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. The residue was crystallized from 2,2′-oxybispropane. The product was filtered off and dried, yielding 5.84 parts (46.1%) of 2-[(4-methyl-1-piperazinyl)methyl]-3H-imidazo[4,5-b]pyridine-3-ethanol; mp. 89.5°C (compound 129). C. Pharmacological examples The useful antihistaminic properties of the compounds of formula (I) are demonstrated in the following test procedure. Example 32 Protection of rats from compound 48/80-induced lethality Compound 48/80, a mixture of oligomers obtained by condensation of 4-methoxy- N -methylbenzeneethanamine and formaldehyde has been described as a potent histamine releasing agent (Int. Arch. Allergy, 13 , 336 (1958)). The protection from compound 48/80-induced lethal circulatory collapse appears to be a simple way of evaluating quantitatively the antihistaminic activity of test compounds. Male rats of an inbred Wistar strain, weighing 240-260 g were used in the experiment. After overnight starvation the rats were transferred to conditioned laboratories (temp. = 21 ± 1°C, relative humidity = 65 ± 5%). The rats were treated subcutaneously or orally with a test compound or with the solvent (NaCl solution, 0.9%). One hour after treatment there was injected intraveneously compound 48/80, freshly dissolved in water, at a dose of 0.5 mg/kg (0.2 ml/100 g of body weight). In control experiments, wherein 250 solvent-treated animals were injected with the standard dose of compound 48/80, not more than 2.8% of the animals survived after 4 hours. Survival after 4 hours is therefore considered to be a safe criterion of a protective effect of drug administration. The ED₅₀-values of the compounds of formula (I) are listed in Table 1. Said ED₅₀-values are the values in mg/kg body weight at which the tested compounds protected 50% of the tested animals against compound 48/80-induced lethality. Compound No. compound 48/80 lethality test in rats-ED₅₀ in mg/kg body weight 14 0.01 17 0.04 42 0.02 44 0.005 46 0.02 47 0.02 74 0.01 76 0.02 77 0.02 79 0.02 93 0.01 105 0.01 110 0.01 111 0.02 120 0.005 125 0.02 126 0.02 D) Composition Examples The following formulations exemplify typical pharmaceutical compositions in dosage unit form suitable for systemic administration to animal and human subjects in accordance with the present invention. "Active ingredient" (A.I.) as used throughout these examples relates to a compound of formula (I), a pharmaceutically acceptable acid additional salt or a stereochemically isomeric form thereof. Example 33 : ORAL DROPS 500 g of the A.I. was dissolved in 0.5 l of 2-hydroxypropanoic acid and 1.5 l of the polyethylene glycol at 60∼80°C. After cooling to 30∼40°C there were added 35 l of polyethylene glycol and the mixture was stirred well. Then there was added a solution of 1750 g of sodium saccharin in 2.5 l of purified water and while stirring there were added 2.5 l of cocoa flavor and polyethylene glycol q.s. to a volume of 50 l, providing an oral drop solution comprising 0.01 g of the A.I. per ml. The resulting solution was filled into suitable containers. Example 34 : ORAL SOLUTION 9 g of methyl 4-hydroxybenzoate and 1 g of propyl 4-hydroxybenzoate were dissolved in 4 l of boiling purified water. In 3 l of this solution were dissolved first 10 g of 2,3-dihydroxybutane-dioic acid and thereafter 20 g of the A.I. The latter solution was combined with the remaining part of the former solution and 12 l 1,2,3-propanetriol and 3 l of sorbitol 70% solution were added thereto. 40 g Of sodium saccharin were dissolved in 0.5 l of water and 2 ml of raspberry and 2 ml of gooseberry essence were added. The latter solution was combined with the former, water was added q.s. to a volume of 20 l providing an oral solution comprising 0.005 g of the A.I. per teaspoonful (5 ml). The resulting solution was filled in suitable containers. Example 35: CAPSULES 20 g of the A.I., 6 g sodium lauryl sulfate, 56 g starch, 56 g lactose, 0.8 g colloidal silicon dioxide, and 1.2 g magnesium stearate were vigorously stirred together. The resulting mixture was subsequently filled into 1000 suitable hardened gelatin capsules, each comprising 0.02 g of the A.I.. Example 36: FILM-COATED TABLETS Preparation of tablet core A mixture of 100 g of the A.I., 570 g lactose and 200 g starch was mixed well and thereafter humidified with a solution of 5 g sodium dodecyl sulfate and 10 g polyvinylpyrrolidone (Kollidon-K 90 ®) in about 200 ml of water. The wet powder mixture was sieved, dried and sieved again. Then there was added 100 g microcrystalline cellulose (Avicel ®) and 15 g hydrogenated vegetable oil (Sterotex ®). The whole was mixed well and compressed into tablets, giving 10.000 tablets, each comprising 0.01 g of the active ingredient. Coating To a solution of 10 g methyl cellulose (Methocel 60 HG ®) in 75 ml of denaturated ethanol there was added a solution of 5 g of ethyl cellulose (Ethocel 22 cps ®) in 150 ml of dichloromethane. Then there were added 75 ml of dichloromethane and 2.5 ml 1,2,3-propanetriol. 10 g Of polyethylene glycol was molten and dissolved in 75 ml of dichloromethane. The latter solution was added to the former and then there were added 2.5 g of magnesium octadecanoate, 5 g of polyvinylpyrrolidone and 30 ml of concentrated color suspension (Opaspray K-1-2109 ®) and the whole was homogenated. The tablet cores were coated with the thus obtained mixture in a coating apparatus. Example 37 : INJECTABLE SOLUTION 1.8 g Methyl 4-hydroxybenzoate and 0.2 g propyl 4-hydroxybenzoate were dissolved in about 0.5 l of boiling water for injection. After cooling to about 50°C there were added while stirring 4 g lactic acid, 0.05 g propylene glycol and 4 g of the A.I. The solution was cooled to room temperature and supplemented with water for injection q.s. ad 1 l volume, giving a solution of 0.004 g A.I. per ml. The solution was sterilized by filtration (U.S.P. XVII p. 811) and filled in sterile containers. Example 38 : SUPPOSITORIES 3 g A.I. was dissolved in a solution of 3 g 2,3-dihydroxybutanedioic acid in 25 ml polyethylene glycol 400. 12 G surfactant (SPAN ®) and triglycerides (Witepsol 555 ®) q.s. ad 300 g were molten together. The latter mixture was mixed well with the former solution. The thus obtained mixture was poured into moulds at a temperature of 37∼38°C to form 100 suppositories each containing 0.03 g of the active ingredient.

Claims: The use of a compound having the formula a pharmaceutically acceptable acid addition salt or a stereochemically isomeric forms thereof, for the manufacture of a medicament for treating allergic diseases, wherein -A¹=A²-A³=A⁴- is a bivalent radical having the formula -N=CH-CH=CH- (a-1), -CH=N-CH=CH- (a-2), -CH=CH-N=CH- (a-3), -CH=CH-CH=N- (a-4), -N=CH-N=CH- (a-5), or -CH=N-CH=N- (a-6), wherein one or two hydrogen atoms in said radicals (a-1) - (a-6) may, each independently from each other, be replaced by halo, C₁₋₆alkyl, C₁₋₆alkyloxy, trifluoromethyl or hydroxy; R¹ is hydrogen, C₁₋₁₀alkyl, C₃₋₆cycloalkyl, Ar¹, C₁₋₆alkyl substituted with one or two Ar¹ radicals, or a radical of formula -Alk-G-R²; wherein R² is hydrogen; C₂₋₆-alkenyl optionally substituted with Ar²; C₃₋₆alkynyl; Ar¹ or C₁₋₆alkyl optionally substituted with Ar¹, hydroxy, C₁₋₆-alkyloxy, carboxyl, C₁₋₆alkyloxycarbonyl, Ar²-oxycarbonyl or Ar²-C₁₋₆alkyloxycarbonyl; and G is O, S or NR³; said R³ being hydrogen, C₁₋₆alkyl, C₁₋₆alkylcarbonyl, C₁₋₆alkyloxycarbonyl or Ar²-C₁₋₆alkyl; R is hydrogen or C₁₋₆alkyl; m is 1 to 4; n is 1 or 2; L is hydrogen, C₁₋₆alkylcarbonyl, C₁₋₆alkylsulfonyl, C₁₋₆alkyloxycarbonyl, Ar²-C₁₋₆alkyoxycarbonyl, Ar²-carbonyl, Ar²-sulfonyl, C₃₋₆cycloalkyl, C₂₋₆alkenyl optionally substituted with Ar², C₁₋₁₂alkyl, a radical of formula -Alk-R⁴ (b-1) -Alk-Y-R⁵ (b-2) -CH₂-CHOH-CH₂-O-R⁷ (b-4); wherein R⁴ is Ar², Het, cyano, isocyanato, isothiocyanato, Ar²-sulfonyl or halo; R⁵ is hydrogen, Ar², Het or C₁₋₆alkyl optionally substituted with halo, Ar² or Het; R⁶ is hydrogen, Ar², Het or C₁₋₆alkyl optionally substituted with halo, Het or Ar²; R⁷ is Ar² or naphthalenyl; Y is O, S, NR⁸; said R⁸ being hydrogen, C₁₋₆alkyl, C₁₋₆alkylcarbonyl or Ar¹-carbonyl; Z¹ and Z² each independently are O, S, NR⁹ or a direct bond; said R⁹ being hydrogen or C₁₋₆alkyl; X is O, S or NR¹⁰; said R¹⁰ being hydrogen, C₁₋₆alkyl or cyano; and each Alk independently being C₁₋₆alkanediyl; Het is a five- or six-membered heterocyclic ring containing 1, 2, 3 or 4 heteroatoms, said heteroatoms being selected from oxygen, sulfur and nitrogen, provided that no more than two oxygens or sulfurs are present, said five or six-membered ring being optionally condensed with a five- or six-membered carbocyclic or heterocyclic ring also containing 1, 2, 3 or 4 heteroatoms, the latter heteroatoms being selected from oxygen, sulfur and nitrogen, provided that no more than 2 oxygens or sulfurs are present, and when said Het is a bicyclic ring system it may optionally be substituted with up to 6 substituents, and when said Het is a monocyclic ring system it may optionally be substituted with up to 4 substituents, said substituents of Het being selected from a bivalent radical of formula =X; halo; isocyanato; isothiocyanato; nitro; cyano; trifluoromethyl; a radical of formula -A; a radical of formula -Y-A; or a radical of formula -Z¹-C(=X)-Z²-A; wherein said =X independently has the same meaning of the previously defined X and A is hydrogen, Ar² or C₁₋₆alkyl being optionally substituted with Ar², C₁₋₆alkyloxy, Ar²-O, hydroxy, or C₁₋₆alkyloxycarbonyl; and Y, Z¹ and Z² independently have the same meaning of the previously defined Y, Z¹ and Z²; provided that (i) when in the radical -Y-A, A is hydrogen, then Y is other than a direct bond, or (ii) when in the radical -Z¹-C(=X)-Z²-A, A is hydrogen and Z¹ is NR⁹ O, or S, then Z² is other than O or S; Ar¹ is phenyl, being optionally substituted with 1, 2 or 3 substituents each independently selected from halo, hydroxy, nitro, cyano, trifluoromethyl, C₁₋₆alkyl, C₁₋₆alkyloxy, C₁₋₆alkylthio, mercapto, amino, mono- and di(C₁₋₆alkyl)amino, carboxyl, C₁₋₆alkyloxycarbonyl and C₁₋₆alkylcarbonyl; thienyl; halothienyl; furanyl; C₁₋₆alkyl substituted furanyl; pyridinyl; pyrimidinyl; pyrazinyl; thiazolyl or imidazolyl optionally substituted with C₁₋₆alkyl; and Ar² is phenyl being optionally substituted with 1, 2 or 3 substituents each independently selected from halo, hydroxy, nitro, cyano, trifluoromethyl, C₁₋₆alkyl, C₁₋₆alkyloxy, C₁₋₆alkylthio, mercapto, amino, mono- and di(C₁₋₆alkyl)amino, carboxyl, C₁₋₆alkyloxycarbonyl and C₁₋₆alkylcarbonyl. A chemical compound of formula (I) as defined in claim 1, provided that when L is C₁₋₂alkyl, R¹ is other than hydrogen, 2-methylphenyl, benzyl, 4-chlorobenzyl or 4-methoxybenzyl. A chemical compound according to claim 2 wherein Het is (i) an optionally substituted five- or six-membered heterocyclic ring containing 1, 2, 3 or 4 heteroatoms selected from oxygen, sulfur and nitrogen, provided that no more than two oxygens or sulfurs are present; or Het is (ii) an optionally substituted five- or six-membered heterocyclic ring containing 1 or 2 heteroatoms selected from oxygen, sulfur and nitrogen, being fused with an optionally substituted five- or six-membered ring through two ring carbon atoms or one ring carbon and one ring nitrogen atom, containing in the remainder of the fused ring only carbon atoms; or Het is (iii) an optionally substituted five- or six-membered heterocyclic ring containing 1 or 2 heteroatoms selected from oxygen, sulfur and nitrogen, being fused with an optionally substituted five- or six-membered heterocyclic ring through two ring carbon atoms or one ring carbon and one ring nitrogen atom, containing in the remainder of the fused ring 1 or 2 heteroatoms selected from oxygen, sulfur and nitrogen; wherein Het may optionally be substituted with up to 4 substituents when Het is a monocyclic ring system, and wherein Het may optionally be substituted with up to 5 substituents when Het is a bicyclic ring system, said substituents of Het being selected from a bivalent radical of formula =X; halo; isocyanato; isothiocyanato; nitro; cyano; trifluoromethyl; a radical of formula -A; a radical of formula -Y-A; or a radical of formula -Z¹-C(=X)-Z²-A; wherein said =X independently has the same meaning of the previously defined X and A is hydrogen, Ar² or C₁₋₆alkyl being optionally substituted with Ar², C₁₋₆alkyloxy, Ar²-O, hydroxy, or C₁₋₆alkyloxycarbonyl; and Y, Z¹ and Z² independently have the same meaning of the previously defined Y, Z¹ and Z²; provided that (i) when in the radical -Y-A, A is hydrogen, then Y is other than a direct bond, or (ii) when in the radical -Z¹-C(=X)-Z²-A, A is hydrogen and Z¹ is NR⁹, O or S, then Z² is other than O or S. A chemical compound according to claim 3 wherein R¹ is C₁₋₆alkyl substituted with Ar¹ or wherein R¹ is a radical -Alk-O-R², said R² being hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆alkynyl or Ar¹. A chemical compound according to claim 4, wherein R is hydrogen, m is 1, n is 1, and L is hydrogen, C₁₋₆alkyl or a radical of formula (b-1), (b-2) or (b-3). A chemical compound according to claim 5, wherein R⁴ is Ar² or Het; R⁵ and R⁶ independently are C₁₋₄alkyl, Ar² or Het; R⁸ is hydrogen or C₁₋₄alkyl; X is O or S; and Z¹ and Z² are each independently NH or a direct bond. A pharmaceutical composition comprising a suitable pharmaceutical carrier and as active ingredient a therapeutically effective amount of a compound as claimed in any one of claims 2 to 6. An anti-allergic pharmaceutical composition comprising a suitable pharmaceutical carrier and as active ingredient an effective anti-allergic amount of a compound as claimed in any one of claims 2 to 6. A method of preparing a pharmaceutical composition, characterized in that a therapeutically effective amount of a compound as defined in any of claims 2 to 6 is intimately mixed with suitable pharmaceutical carriers. A compound as claimed in any of claims 2 to 6 for use as a medicine. A compound as claimed in any of claims 2 to 6 for use as an anti-allergic medicine. A process for preparing a chemical compound as claimed in any of claims 2 to 6, characterized by a) cyclizing an intermediate of formula wherein X³ is O, S or NH, in a reaction-inert solvent, if desired, in the presence of a dehydrating agent; b) reacting an acid of formula or a functional derivative thereof, with an aromatic diamine of formula in a reaction-inert solvent; c) N-alkylating a piperazine or hexahydro-1 H -1,4-diazepine of formula with an imidazopyridine or imidazopyrimidine of formula wherein W is a reactive leaving group, in a reaction-inert solvent; if desired, in the presence of a base; d) reductively N-alkylating a piperazine or hexahydro-1 H -1,4-diazepine of formula with an imidazopyridine or imidazopyrimidine of formula in a reductive medium; e) reacting a piperazine or hexahydro-1 H -1,4-diazepine of formula with an imidazopyridine or imidazopyrimidine of formula or the metal substitution form thereof, in a reaction-inert medium; f) N -alkylating a compound of formula with a reagent of formula W-R 1-a (XI), wherein W is a reactive leaving group, in a reaction-inert solvent, thus preparing a compound of formula wherein R 1-a has the same meaning of R¹ provided that it is other than hydrogen; or g) N -alkylating a compound of formula H-D (I-d) with a reagent of formula L¹-W (XI) in a reaction-inert solvent, thus preparing a compound of formula L¹-D (I-c), wherein L¹ has the previously defined meaning of L, provided that it is other than hydrogen; h) reductively N -alkylating a compound of formula H-D (I-d) with a ketone or aldehyde of formula L²=O (XII), said L²=O being an intermediate of formula L²H₂ wherein two geminal hydrogen atoms are replaced by =O, in a reductive medium thus preparing a compound of formula L²H-D (I-c-1); wherein L² is a geminal bivalent radical comprising C₃₋₆cycloalkylidene, C₁₋₁₂alkylidene, R⁴-C₁₋₆alkylidene, R⁵-Y-C₁₋₆alkylidene and R⁶-Z²-C(=X)-Z¹-C₁₋₆alkylidene; i) alkylating a compound of formula H-Y-Alk-D (I-c-3) with an intermediate of formula R 5-a -W¹ (XIII), wherein R 5-a is Ar² or Het, in a reaction-inert solvent, thus preparing a compound of formula R 5-a -Y-Alk-D (I-c-2); j) alkylating an intermediate of formula R 5-a -Y-H (XIV) wherein R 5-a is Ar² or Het with a compound of formula W-Alk-D (I-c-4), in a reaction-inert solvent, thus preparing a compound of formula (I-c-2); k) reacting a reagent of formula R⁶-Z 2-a -H (XV), wherein Z 2-a has the previously defined meaning of Z² provided that it is other than a direct bond, with a compound of formula X=C=N-Alk-D (I-c-6), in a reaction-inert solvent, thus preparing a compound of formula R⁶-Z 2-a -C(=X)-NH-Alk-D (I-c-5); l) reacting an isocyanate or isothiocyanate of formula R⁶-N=C=X (XVI) with a compound of formula H-Z 1-a -Alk-D (I-c-8), wherein Z 1-a has the previously defined meaning of Z² provided that it is other than a direct bond, in a reaction-inert solvent, thus preparing a compound of formula R⁶-NH-C(=X)-Z 1-a -Alk-D (I-c-7); m) reacting a reagent of formula R⁶-C(=X)-OH (XVII) with (I-c-8), in a reaction-inert solvent, if desired, after converting the OH group in (XVII) in a reactive leaving group or by reacting (XVII) with (I-c-8) in the presence of a reagent capable of forming esters or amides, thus preparing a compound of formula R⁶-C(=X)-Z 1-a -Alk-D (I-c-9); n) reacting an alkenylene of formula L³-C₂₋₆alkenediyl-H (XVIII), wherein L³ being Ar², Het, Ar²-sulfonyl or a radical of formula R⁶-Z²-C(=X)-, with a compound of formula (I-d), in a reaction-inert solvent, thus preparing a compound of formula L³-C₂₋₆alkenediyl-D (I-c-10); o) reacting a reagent of formula wherein R²⁵ is hydrogen or a radical R⁷-O-CH₂-, with a compound of formula (I-d), in a reaction-inert solvent, thus preparing a compound of formula R²⁵-CH(OH)-CH₂-D (I-c-11); p) cyclodesulfurizing a compound of formula with an alkylhalide, metal oxide or metal salt in a reaction-inert solvent, thus preparing a compound of formula wherein G⁵ and R²² are as previously defined; or q) cyclizing a guanidine derivative of formula in a reaction inert-solvent, thus preparing a compound of formula wherein R²⁶ is hydrogen, C₁₋₆alkyl or Ar2-C₁₋₆alkyl; wherein D represents a radical of formula wherein -A¹=A²-A³=A⁴-, R, R¹, n and m have the previously described meanings; or optionally converting the compounds of formula (I) into each other following art-known groups transformation procedures, and, if desired, converting the compounds of formula (I) into a therapeutically active non-addition salt form by treatment with an appropriate acid or, conversely, converting the acid-addition salt into the free base form with alkali; and/or preparing stereochemically isomeric forms thereof.

Inventors: DIELS, GASTON S.M., JANSSENS, FRANS E., SOMMEN, FRANCOIS M., TORREMANS, JOSEPH L.G., Sommen, François M.
Applicants: JANSSEN PHARMACEUTICA N.V.
Application year: 1988
Main classification: A61K31
IPC codes: C07D471, A61K31, C07D473, A61P37, C07D519