Abstract:
The invention relates to novel pyrido 3,2-e!pyrazinones, processes for their preparation and their pharmaceutical use. 
     The compounds have anti-asthmatic and anti-allergic effects.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to novel compounds of the formula ##STR1## 
     where 
     A either represent CH 2 , NR 3  or O; 
     X, Y and Z stand for N or CR 4 , where at least one of X, Y and Z must represent N. 
     R 1  can represent H (but only when A stands for NR 3 ); and C 1  -C 10  -alkyl (optionally also branched), that can be substituted once or several times with hydroxy-, C 1  -C 6  -alkyloxy, C 1  -C 6  -alkenyloxy-, C 1  -C 6  -alkinyloxy, aryl (optionally substituted), aryloxy (optionally substituted), heteroaryl (optionally substituted), heteroaryloxy (optionally substituted), amino, substituted amino groups, but also with halogen, NO 2 , CN, C=OR 5  or S(O) n  R 6  (with n from 0 to 2); C 1  -C 10  -alkenyl (optionally also branched), that can be substituted once or several times with hydroxy, C 1  -C 6  -alkyloxy, C 1  -C 6  -alkenyloxy, C 1  -C 6  -alkinyloxy, aryl (optionally substituted), aryloxy (optionally substituted), heteroaryl (optionally substituted), heteroaryloxy (optionally substituted), amino, substituted amino groups, but also with halogen, NO 2 , CN, C=OR 5  or S(O) n  R 6  (with n from 0 to 2); C 1  -C 10  -alkinyl (optionally also branched), that can be substituted once or several times with hydroxy, C 1  -C 6  -alkyloxy, C 1  -C 6  -alkenyloxy, C 1  -C 6  -alkinyloxy, aryl (optionally substituted), aryloxy (optionally substituted), heteroaryl (optionally substituted, heteroaryloxy (optionally substituted), amino, substituted amino groups, but also with halogen, NO 2 , CN, C=OR 5  or S(O) n  R 6  (with n from 0 to 2); C 5  -C 7  -cycloalkyl that can be substituted once or several times with hydroxy, C 1  -C 6  -alkyloxy, C 1  -C 6  -alkenyloxy, C 1  -C 6  -alkinyloxy, aryl (optionally substituted), aryloxy (optionally substituted), heteroaryl (optionally substituted), heteroaryloxy (optionally substituted), amino, substituted amino groups, but also with halogen, NO 2 , CN, C=OR 5  or S(O) n  R 6  (with n from 0 to 2). 
     R 2  can stand for H; C 1  -C 10  -alkyl (optionally also branched), that can be substituted once or several times with hydroxy, C 1  -C 6  -alkyloxy, C 1  -C 6  -alkenyloxy, C 1  -C 6  -alkinyloxy, aryl (optionally substituted), aryloxy (optionally substituted), heteroaryl (optionally substituted), heteroaryloxy (optionally substituted), amino, substituted amino groups, but also with halogen, NO 2 , CN, C=OR 5  or S(O) n  R 6  (with n from 0 to 3); C 1  -C 10  -alkenyl (optionally also branched), that can be substituted once or several times with hydroxy, C 1  -C 6  -alkyloxy, C 1  -C 6  -alkenyloxy, C 1  -C 6  -alkinyloxy, aryl (optionally substituted), aryloxy- (optionally substituted), heteroaryl (optionally substituted), heteroaryloxy (optionally substituted), amino, substituted amino groups, but also with halogen, NO 2 , CH, C=OR 5  or S(O) n  R 6  (with n from 0 to 2); C 1  -C 10  -alkinyl (optionally also branched) that can be substituted once or several times with hydroxy, C 1  -C 6  -alkyloxy, C 1  -C 6  -alkenyloxy, C 1  -C 6  -alkinyloxy, aryl (optionally substituted), aryloxy (optionally substituted), heteroaryl (optionally substituted), heteroaryloxy (optionally substituted), amino, substituted amino groups, but also with halogen, NO 2 , CN, C=OR 5  or S(O) n  R 6  (with n from 0 to 2); C 5  -C 7  -cycloalkyl, that can be substituted once or several times with hydroxy, C 1  -C 6  -alkyloxy, C 1  -C 6  -alkenyloxy, C 1  -C 6  -alkinyloxy, aryl (optionally substituted), aryloxy (optionally substituted), heteroaryl (optionally substituted), heteroaryloxy (optionally substituted), amino, substituted amino groups, but also with halogen, NO 2 , C=OR 5  or S(O) n  R 6  (with n from 0 to 2). 
     R 3  stands for H or C 1  -C 6  -alkyl. 
     R 4  represents H; C 1  -C 6  -alkyl (optionally branched); halogen. 
     R 5  stands for H; C 1  -C 6  -alkyl (optionally branched); phenyl; OH; C 1  -C 6  -alkyloxy (optionally branched); aryloxy (optionally substituted); amino (optionally substituted). 
     R 6  represents H; C 1  -C 6  -alkyl; aryl (optionally substituted); OH; C 1  -C 6  -alkyloxy; aryloxy (optionally substituted); amino (optionally substituted). 
     The invention also relates to the physiologically acceptable salts of the compounds of formula I, the processes for the preparation of the compounds of formula I and their pharmaceutical use. 
     2. Background Information 
     European patent application 0 400 583 relates to imidoquinoxalines and their aza-analogs of the general formula ##STR2## where A represent a nitrogen atom or CH, B and D a nitrogen atom or CH or a substituted carbon atom and the radicals R, R 1 , R 2  represent hydrogen or various organic substituents. These compounds are said to have a positive inotropic vessel-dilating effect. 
     Furthermore, indian Journal of Chemistry, Volume 10, 1972, pages 344-350 describes inter alia the preparation of compounds of formula ##STR3## 
     
         R=--(CH.sub.2).sub.n NR.sup.1 R.sup.2, 
    
     where the radical R can be 3-dimethylaminopropyl-(1), 2-morpholinoethyl-(1), 2-pyrrolidinoethyl-(1) or 2-dimethylaminoethyl-(1). No pharmacological effect is given. 
     European patent application 0 584 487 relates to 4,5-dihydro-4-oxo-pyrrolo 1,2-a!-quinoxalines and their aza-analogs of general formula ##STR4## where the radicals R 1 , R 2  R 3  and R 4  stand for a plurality of organic substituents. These compounds are described as having anti-allergic, anti-asthmatic, anxiolytic, hypotensive and vasodilatory effects as well as a positive inotropic effect which are causatively based on a selective PDE III inhibition. 
     Patent application WO(PCT) 93 20 077 relates to imidazoquinoxalinones of general formula ##STR5## where A stands for 5-ring heterocycles with 2 or 3 nitrogen atoms in the ring, R 1  can be NO 2  or CF 3  and X stands for various in part nitrogen-containing chains with up to 4 chain members. 
     These compounds are described as glutamate receptor antagonists with psychotropic and anti-ischaemic effect. 
     Japanese patent application JP 06 128 261 and JP 06 128 262 relate to the preparation of compounds of general formula ##STR6## where the radicals R 1 , R 2 , R 3  and R 4  stand for various organic substituents. No pharmacological effect is given. 
     European patent application 0 623 620 relates to the preparation of compounds of general formula ##STR7## where A stands for anellated aromatic or heteroaromatic ring systems and R 1  for substituted amino groups. The compounds described have in part 5HT 3  -antagonist effects. 
     European patent application 0 518 530 relates to the preparation of compounds of the general formulae ##STR8## where R 1 , R 2  and R 3  stand for various organic substituents and A 1  to A 5  for C or N, where at least two of them represent N. These compounds are antagonists of receptors of excitatory amino acids. Published German patent application DE 43 29 970 relates to the preparation of compounds of general formula ##STR9## where A stands for a saturated or unsaturated alkylene group with 1-5 carbon atoms, R 1 , R 2 , R 3 , R 4  and R 5  represent various organic substituents and R 6  stands for a functional group that contains a carbonyl group. These compounds are described as antagonists of receptors of excitatory amino acids. 
     SUMMARY OF THE INVENTION 
     The invention describes the compounds set out in the patent claims. The new compounds according to the invention are pharmacologically active and have in particular strong anti-asthmatic and anti-allergic effects on the basis of selective PDE IVN inhibition. 
     It is an object of the invention to provide new compounds having valuable pharmacological properties. 
     The invention also relates to processes for the preparation of the new compounds described in the patent claims as well as to the use thereof. 
     Those compounds of formula I, which contain asymmetric carbon atoms and generally occur as racemates can be separated into the optically active isomers in a manner known per se, for example with an optically active acid. It is, however, also possible from the beginning to use an optically active starting substance, a correspondingly optically active or diastereomeric compound then being obtained. Of compounds of formula I, which contain an asymmetric carbon atom, the invention therefore comprises the D-form, the L-form and D,L-mixtures as well as the diastereomeric forms in the case of several asymmetric carbon atoms. Depending on the process conditions and starting substances, the compounds of formula I can be obtained as free compounds or in the form of their salts. The salts obtained can be converted into the free bases in a manner known per se, for example with alkali or ion exchangers, or into the free acids with inorganic or organic acids. Salts can be obtained from the compounds of formula I released in this manner by reaction with inorganic or organic acids or with inorganic or organic bases that are suitable for the formation of therapeutically usable salts. 
     The compounds of the invention are suitable for the preparation of pharmaceutical formulations. The pharmaceutical formulations can contain one or several of the compounds of the invention. Conventional physiologically acceptable diluting agents, carriers and auxiliary substances can be used to prepare the pharmaceutical formulations or therapeutically usable forms. 
     In accordance with the invention compounds of formula I are prepared by reacting compounds of formula ##STR10## where X, Y, Z, A and R 2  have the meaning given, with R 1  - Hal (Hal=halogen) in the presence of an inorganic or organic basic catalyst, where R 1  has the meaning given. The process can be carried out without solvents or in a suitable solvent or dispersing agent. Solvents or dispersing agents that can for example be considered are: aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene; lower aliphatic ketones such as acetone, methylethyl ketone, diethyl ketone; ethers such as diethyl ether, tetrahydrofuran, dioxan; sulfoxides such as dimethylsulfoxide; tertiary acid amides such as dimethyl formamide, dimethyl acetamide, tetramethylurea, hexamethylphosphoric acid triamide, N-methylpyrrolidone; halogenated hydrocarbons such as chlorobenzene, dichlorobenzene, carbon tetrachloride; lower alcohols such as methanol, ethanol, isopropanol as well as mixtures of the agents stated, optionally also with water. The reaction is for example carried out at temperatures between 20° and 200° C., preferably 50° to t 30° C. In the case of the starting component R 1  - Hal, Hal preferably represents chlorine, bromine or iodine. 
     The reaction is preferably carried out in the presence of acid binding agents such as alkali carbonates (sodium carbonate, potassium carbonate), alkali acetates, alkali hydroxides or tertiary basis (triethylamine, pyridine). The starling components of formula II are preferably used in the form of their metal salts. Alkali salts can be used in particular. The preparation of alkali salts is effected for example by reaction with the corresponding alkali hydrides, alkali amides, alkali alcoholates or also alkali metals in a solvent (lower alcohol, aromatic hydrocarbon, tertiary acid amides) or with aqueous alkali (for example NaOH). 
     In accordance of the invention, compounds of formula I are also prepared by reacting compounds of formula ##STR11## where A, X, Y, Z and R 1  have the meaning given, with R 2  -Hal (Hal=halogen) in the presence of an inorganic or organic basic catalyst, where R 2  has the meaning given. The process can be carried out without solvent or in a suitable solvent or dispersing agent. Solvents or dispersing agents that can, for example, be considered are: aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene; lower aliphatic ketones such as acetone, methylethyl ketone, diethyl ketone; ethers such as diethyl ether, tetrahydrofuran, dioxan; sulfoxides such as dimethyl sulfoxide; tertiary acid amides such as dimethylformamide, dimethylacetamide, tetramethylurea, hexamethylphosphoric acid triamide, N-methylpyrrolidone; halogenated hydrocarbons such as chlorobenzene, dichlorobenzene, carbon tetrachloride; lower alcohols such as methanol, ethanol, isopropanol and mixtures of the agents mentioned, optionally also with water. The reaction is for example carried out at temperatures between 20° and 200° C., preferably at 50° to 130° C. 
     In the case of the starting component R 2  - Hal, Hal preferably represents chlorine, bromine or iodine. 
     The reaction is preferably carried out in the presence of acid-binding agents such as alkalicarbonates (sodium carbonate, potassium carbonate), alkali acetates, alkali hydroxides or tertiary bases (triethylamine, pyridine). The starting components of formula Ill are preferably used in the form of their metal salts. The alkali salts are particularly suitable. The preparation of the alkali salts is effected for example by reaction with the corresponding alkali hydrides, alkali amides, alkali alcoholates or also alkali metals in a solvent (lower alcohol, aromatic hydrocarbon, tertiary acid amides) or with aqueous alkali (for example NaOH). 
     The new pyrido 3,2-e!pyrazinones can be converted into the corresponding salts with inorganic or organic acids or bases in water or in organic solvents. The compounds of the invention of formula I and their salts are biologically active. The compounds of the invention display a strong in vitro inhibition of the phosphodiesterase isoenzyme IV and V, a strong influence of the trachea recontracted by histamine (guinea pigs) as well as good effects in in vivo asthma models, such as in the asthmatic late phase reaction (eosinosphilia) in guinea pigs. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Methods 
     Determination of phosphodiesterase activity 
     Phosphodiesterase (PDE) activity is determined with a few modifications (Bauer, A. C.; Schwabe, U., An improved assay of cyclic 3&#39;,5&#39;-nucleotide phosphodiesterase with QAE Sephadex A-25. Naunyn-Schmiedeberg&#39;s Arch. Pharmacol. 311 193-198 (1980)) after the method described by Thompson et al. (Thompson, W. J.; Appleman, M. M., Assay of cyclic nucleotide phosphodiesterase and resolution of multiple molecular forms of the enzyme. Adv. Cycl. Nucl. Res. 10 69-92 (1979)) The reaction mixture contains 40 mM Tris-HCl (pH 7.4), 5 mM MgCl 2 , 0.5 μM cAMP or cGMP,   3  H!cAMP or   3  H!cGMP (approx. 20,000 cpm/test) and the other components needed to record the individual isoenzymes (see below). The final volume is 200 μl. Test substances are prepared as stock solutions in DMSO. The DMSO concentration in the reaction mixture is the same or less than 1% v/v. The PDE activity is not influenced at this DMSO concentration. After pre-incubation for 5 minutes at 37° C. the reaction is started by adding the substrate (cAMP or cGMP). The samples are incubated for a further 15 minutes at 37° C. The reaction is stopped by adding 50 μl 0.2N HCl. The samples remain in the ice for a further 10 minutes. After incubation with 25 μg 5&#39;-nucleotidase (Crotalus atrox) for 10 minutes at 37° C. the samples are applied to QAE Sephadex A-25 columns (Econor columns, Bio-Rad). The columns are eluted with 2 ml 30 mM ammonium formiate (pH 6.0). The radioactivity of the individual fractions is recorded using scintigraphy. 
     The PDE IV (cAMP-specific) activity is determined after the method described by Schudt et al. (Schudt C.; Winter S.; Forderkurz S.; Hatzelmann A.; Ullrich V., Influence of selective phosphodiesterase inhibitors on human neutrophil functions and levels of cAMP and Ca. Naunyn-Schmiedeberg&#39;s Arch. Pharmacol. 344, 682-690 (1991)) describe a method in the cytosol of human polymorpho-nuclear leucocytes. The substrate is cAMP. Addition of motapizon, a specific PDE III inhibitor (1 μM) totally suppresses the PDE III activity stemming from the possible thrombolytic impurity. 
     PDE V (cGMP-specific) is isolated from human blood platelets (Schudt C.; Winder S.; Muller B.; Ukena D., Zardaverine as a selective inhibitor of phosphodiesterase isoenzymes. Biochem. Pharmacol. 42, 153-162 (1991)). cGMP is used as substrate. 
     Influence on the trachea precontracted using histamine 
     Guinea pigs are exsanguinated under narcosis. The trachea is then prepared free from adjacent tissue and cut into five equal parts (at least 3 trachea-rings wide). The trachea parts are suspended in a bath filled with a nutrient solution (Krebs-Henseleit). The strength of contraction of the trachea can be measured using force transducers. After suspension, a 15-minute acclimatisation period is allowed. The trachea is then totally relaxed using isoprenaline (1×10 -7  mol/l). The bath vessel is then rinsed. A contraction maximum is triggered using metacholine (10×10 -5  mol/l). The bath vessel is then rinsed again. Histamine (1×10 4  mol/l) is then added. The contraction maximum is reached after approx. 10 minutes. The test substance is then added to the bath in increasing concentration and the contraction-triggering effect determined in percent to an untreated control. The mean contraction-triggering concentration is calculated using regression apparatuses. To check the function of the organs, isoprenaline (1×10 -5  mol/l) is then added to the bath to see whether the organs are still able to relax. 
     Determination of the asthmatic late phase reaction (oesinophilia) in guinea pigs 
     Male guinea pigs (250-300 g, Pirbright white, Charles River Wiga) are actively sensitised by s.c. injection of ovalbumin (10 μg+100 mg aluminium hydroxide) and boosted 2 weeks later. One week after the boosting (10 μg+100 mg aluminium hydroxide) the animals are exposed of an aerosol of nebulised 0.5 % ovalbumin solution for 20 seconds. 24 hours later, the bronchoalveolar lavage (BAL) is carried out using 2×5 ml sodium chloride solution on animals sacrificed with an overdose of pentobarbital. The lavage liquid is pooled and centrifuged for 10 minutes. The cell pellet is suspended in 1 ml physiological sodium chloride solution and the eosinophils are counted microscopically in a counting chamber using a Becton-Dickinson eosinophil kit. The eosinophils are counted for each guinea pig. The mean value is calculated for each group. The inhibition of the eosinophils for the group treated with substance is obtained using the formula: 
     
         (A-C)-(B-C)/(A-C)×100=% inhibition 
    
     A=Eosinophils in the untreated control group challenged with ovalbumin 
     B=Eosinophils in the group treated with the substance and challenged with ovalbumin 
     C=Eosinophils in the control group not challenged with ovalbumin 
     The substance was applied 2 hours before allergen challenge p,o, (in 1% methocel) or i.p. (in 0.5% methocel). The control groups receive 1% methocel p.o. or 0.5% methocel i.p. 2 hours before allergen challenge. 
     The following effects were for example obtained for the compound according to embodiment 1: 
     PDE IV--inhibition (in vitro): IC 50  =0.1 μmol/l 
     PDE V--inhibition (in vitro): IC 50  =0.095 μmol/l 
     Histamine precontracted trachea: IC 50  =0.7 μmol/l 
     Ovalbumin-induced eosinophilia (guinea pigs): 1 mg/kg i.p. 74% inhibition. 
     EMBODIMENTS 
     Examples for the preparation of compounds of formula I from compounds of formula II: 
    
    
     EXAMPLE 1 
     1-ethyl-8-methoxy-3-methyl-5-propyloimidazo 1,5-a!pyrido 3,2-e!-pyrazinone 
     Variant A 
     10 g (0.038 mol) 1-ethyl-8-methoxy-3-methyl-imidazo 1,5-a!pyrido 3,2-e!pyrazinone are stirred into 200 ml dimethylformamide. 3 g (0.095 mol) sodium hydride (80%) are added in portions at 20° C. with stirring. After the mixture has been stirred for 2 hours, 8.5 g (0.07 mol) n-propyibromide are added dropwise within 15 minutes. The resulting solution is heated to 70°-80° C. for 2 hours with stirring and then heated for a further 8 hours to 100° C. The solvent is removed in a vacuum after cooling to 20° C. The raw product crystallising is first stirred out with 150 ml of water at about 50° C. and then recrystallised from cyclohexane. 
     Yield: 8.5 g (73% of theory) 
     Melting point: 136°-137° C. 
     Variant B 
     10 g (0.038 mol) 1-ethyl-8-methoxy-3-methyl-imidazo 1,5-a!pyrido 3,2-e!pyrazinone are stirred into 200 ml dimethylacetamide. 3 g (0.095 mol) sodium hydride (80%) are added in portions at 20° C. with stirring. After the mixture has been stirred for 2 hours 8.5 g (0.07 mol) n-propyl bromide are added dropwise within 15 minutes. The resultant solution is stirred for a further 15 hours at 20°-25° C. The solvent is then removed in a vacuum. The crystallising raw product is purified as described for variant A. Yield: 
     8.1 g (70% of theory) 
     Melting point: 135°-137° C. 
     Variant C 
     10 g (0.038 mol) 1-ethyl-8-methoxy-3-methyl-imidazo 1,5-a!pyrido 3,2-e!pyrazinone are heated to 120° C. with 6.9 g (0.05 mol) anhydrous potassium carbonate in 80 ml dimethylformamide with stirring. 8.5 g (0.07 mol) n-propyl bromide are then added dropwise within 15 minutes. The reaction mixture is stirred for 7 hours at 120°-130° C. After cooling the inorganic salts are suctioned off and the solvent removed from the filtrate in the vacuum. The mixture is recrystallised from cyclohexane to purify the crystallising raw product. 
     Yield: 8.0 g (69% of theory) 
     Melting point: 135°-137° C. 
     Numerous further compounds of formula I can be prepared using the variants given by way of example, the following being set out by way of example: 
     
                                           TABLE 1__________________________________________________________________________                                  Yield                                     Melting pt.ExampleX    Y Z    A R.sup.1   R.sup.2                              Variant                                   %!                                      °C.!__________________________________________________________________________2    C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.3  H     B   92 276-278                                     Ethanol3    C--CH.sub.3     N C--C.sub.2 H.sub.5            O C.sub.2 H.sub.5                        H     B   90 157-160                                     Ethanol4    C--CH.sub.3     N C--C.sub.2 H.sub.5            O C.sub.3 H.sub.7                        H     B   77 295                                     Ethanol5    C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.3  CH.sub.3                              B   74 173                                     DMF6    C--CH.sub.3     N C--H O CH.sub.3  CH.sub.3                              B   76 254                                     Ethyl acetate7    C--H N C--CH.sub.3            O CH.sub.3  CH.sub.3                              B   80 279                                     DMF8    C--CH.sub.3     N C--C.sub.2 H.sub.5            O C.sub.2 H.sub.5                        CH.sub.3                              B   68 145-147                                     DMF9    C--CH.sub.3     N C--H O C.sub.2 H.sub.5                        CH.sub.3                              B   67 177                                     Ethyl acetate10   C--CH.sub.3     N C--C.sub.2 H.sub.5            O C.sub.4 H.sub.9                        CH.sub.3                              C   54  99-102                                     Cyclohexane11   C--CH.sub.3     N C--C.sub.2 H.sub.5            O C.sub.5 H.sub.11                        CH.sub.3                              A   33 72-74                                     Cyclohexane12   C--CH.sub.3     N C--C.sub.2 H.sub.5            O (CH.sub.2).sub.2 CH(CH.sub.3).sub.2                        CH.sub.3                              A   11 113-116                                     Cyclohexane13   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.5                        CH.sub.3                              B   44 166-167                                     Acetone14   C--CH.sub.3     N C--C.sub.2 H.sub.5            O C.sub.2 H.sub.4 C.sub.6 H.sub.5                        CH.sub.3                              C   10 174-176                                     Acetone15   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.4 (2-Cl)                        CH.sub.3                              A   58 245-246                                     DMF16   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.4 (4-Cl)                        CH.sub.3                              A   64 201-202                                     DMF17   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.3 (2,4-di-Cl)                        CH.sub.3                              C   17 211-213                                     Acetone18   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.3 (2,6-di-Cl)                        CH.sub.3                              A   33 209-212                                     Toluene19   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.4 (2-F)                        CH.sub.3                              A   51 186-187                                     Ethanol20   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.4 (4-F)                        CH.sub.3                              A   60 189-191                                     DMF21   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.3 (2-Cl,6-F)                        CH.sub.3                              A   26 197-200                                     Acetone22   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.4 (2-CH.sub.3)                        CH.sub.3                              A   50 240-242                                     Toluene23   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.4 (4-OCH.sub.3)                        CH.sub.3                              A   61 156-158                                     Ethanol24   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.2 (3,4,5-tri-                        CH.sub.3                              A   69 191-192              OCH.sub.3              Ethanol25   C--CH.sub.3     N C--C.sub.2 H.sub.5            O CH.sub.2 C.sub.6 H.sub.4 (4-OCH.sub.2 --                        CH.sub.3                              A   54 147-149              C.sub.6 H.sub.5)       Ethanol26   C--CH.sub.3     N C--C.sub.2 H.sub.5            O (CH.sub.2).sub.3 COOC.sub.2 H.sub.5                        CH.sub.3                              B   57 130-132                                     Isopropanol27   C--CH.sub.3     N C--C.sub.2 H.sub.5            O (CH.sub.2).sub.3 COONa                        CH.sub.3                              B   65 293-295                                     Ethanol28   C--CH.sub.3     N C--C.sub.2 H.sub.5            O C.sub.3 H.sub.7                        C.sub.2 H.sub.5                              B   67 124-126                                     Ethanol29   C--CH.sub.3     N C--C.sub.2 H.sub.5            O C.sub.2 H.sub.5                        CH.sub.2 COCH.sub.3                              B   70 174-176                                     Ethanol__________________________________________________________________________ 
    
     Examples for the preparation of compounds of formula I from compounds of formula III: 
     EXAMPLE 30 
     8-cyclopentyloxy-1-ethyl-3-methyl-5-propyl-imidazo 1,5-a!pyrido 3,2-e!-pyrazinone 
     Variant A 
     3.2 g (0.11 mol) 1-ethyl-8-hydroxy-3-methyl-imidazo 1,5-a!pyrido 3,2-e!pyrazinone are stirred into 60 ml dimethylformamide. 0.9 g (0.03 mol) sodium hydride (80%) are added in portions at 20° C. After the mixture has been stirred for 2 hours 2.1 g (0.02 mol) cyclopentyl chloride are added dropwise within 15 minutes. The resulting solution is heated to 70°-80° C. with stirring for 2 hours and then heated for a further 8 hours to 100° C. After cooling to 20° C. the solvent is removed in a vacuum. The raw product that crystallises is first stirred out with 50 ml hot water at about 50° C. and then recrystallised from ethyl acetate. 
     Yield: 3.0 g (77% of theory) 
     Melting point: 138°-140° C. 
     Variant B 
     3.2 g (0.011 mol) 1-ethyl-8-hydroxy-3-methyl-imidazo 1,5-a!pyrido 3,2-e!pyrazinone are stirred into 60 ml dimethylacetamide. 0.9 g (0.03 mol) sodium hydride (80%) are added in portions at 20° C. with stirring. After the mixture has been stirred for 2 hours 2.1 g (0.02 mol) cyclopentyl chloride are added dropwise within 15 minutes. The resultant solution is stirred for a further 15 hours at 20°-25° C. The solvent is then removed in a vacuum. Purification of the crystallising raw product is carried out as described for variant A. 
     Yield: 2.7 g (70% of theory) 
     Melting point: 138°-140° C. 
     Numerous further compounds of formula I can be prepared using the variants given by way of example, the following being set out by way of example: 
     
                                           TABLE 2__________________________________________________________________________                                               Yield                                                   Melting pt.ExampleX    Y  Z    A   R.sup.1  R.sup.2          Variant                                                %!  °C.!__________________________________________________________________________31   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3 C.sub.2 H.sub.5  B   97  216                                                   DMF32   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                          C.sub.2 H.sub.5  A   43  132-134                                                   Isopropanol33   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3 CH.sub.2 COCH.sub.3                                           B   61  174-175                                                   Ethanol34   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3 (CH.sub.2).sub.3 COCH.sub.3                                           B   22  142-143                                                   Ethanol35   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                          (CH.sub.2).sub.2 CH.sub.2 OH                                           B   24  140-142                                                   Isopropanol36   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                          (CH.sub.2).sub.2 CH.sub.2 SO.sub.3                                           B   67  336-337                                                   Isopropanol37   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3 (CH.sub.2).sub.3 COOH                                           B   37  233-235                                                   Isopropanol38   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                          (CH.sub.2).sub.3 COOH                                           B   70  165                                                   Ethanol39   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3 (CH.sub.2).sub.3 COOC.sub.2 H.sub.5                                           B   94  140-141                                                   DMF40   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                          (CH.sub.2).sub.3 COOC.sub.2 H.sub.5                                           B   17   78                                                   Ethanol41   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                          (CH.sub.2).sub.3 CON(CH.sub.3)C.sub.6                          H.sub.11         B   11  133-135                                                   Ethyl acetate42   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3 CH.sub.2 C.sub.6 H.sub.5                                           B   70  165                                                   DMF43   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                          CH.sub.2 C.sub.6 H.sub.5                                           B   27  147-148                                                   Isopropanol44   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3 CH.sub.2 C.sub.6 H.sub.4 (4-F)                                           B   67  223                                                   Isopropanol45   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                          CH.sub.2 C.sub.6 H.sub.4 (4-F)                                           B   52  148-150                                                   Isopropanol46   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.2 C.sub.6 H.sub.2 (3,4,5-tri-                          CH.sub.2 C.sub.6 H.sub.2 (3,4,5-tri-                                           A   52  172-174                 OCH.sub.3)                          OCH.sub.3)               Cyclohexane47   CCH.sub.3     N  CC.sub.2 H.sub.5             NH  H        CH.sub.2 C.sub.6 H.sub.5                                           B   40  276-278                                                   Ethanol48   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3                           ##STR12##       B    9                                                    ##STR13##49   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3                           ##STR14##       B    3                                                    ##STR15##50   CCH.sub.3     N  CC.sub.2 H.sub.5             O   CH.sub.3                           ##STR16##       B   18                                                    ##STR17##51   CCH.sub.3     N  CC.sub.2 H.sub.5             O   C.sub.2 H.sub.5                           ##STR18##       A   13                                                    ##STR19##__________________________________________________________________________