Abstract:
Disclosed are quinoxalinone compounds of the formula I or Ia ##STR1## and physiologically tolerated salts and prodrugs thereof, in which n=zero, one or two; 
     R 1  =fluorine, chlorine, hydroxyl or C 1  -C 3  -alkoxy; R 2  =C 1  -C 4  -alkyl which is unsubstituted or is substituted by hydroxyl, C 1  -C 4  -alkoxy or C 1  -C 4  -alkylthio; R 3  =C 1  -C 6  -alkyloxycarbonyl or C 2  -C 6  -alkenyloxycarbonyl, and X=oxygen, sulfur or selenium, a process for their preparation and pharmaceutical compositions containing the compounds.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to quinoxalines, to a process for their preparation, and to their use as virustatic agents, in particular for treating infections with the human immunodeficiency virus (HIV). 
     2. Description of Related Art 
     European Patent Application EP-509398-A describes quinoxaline derivatives for treating infections with the human immunodeficiency virus (HIV). 
     SUMMARY OF THE INVENTION 
     It has now been found, surprisingly, that a group of specially substituted quinoxalines of the formula I, ##STR2## and their tautomeric forms of the formula Ia ##STR3## and also their physiologically tolerated salts or prodrugs exhibit an antiviral effect, in particular against retroviruses, such as, for example, human immunodeficiency virus (HIV). 
     In the novel compounds of the formula I or Ia: 
     1) n is zero, one or two, 
     R 1  is fluorine, chlorine, hydroxyl or C 1  -C 3  -alkoxy, 
     R 2  is C 1  -C 4  -alkyl which is optionally substituted by hydroxyl, C 1  -C 4  -alkoxy or C 1  -C 4  -alkylthio, 
     R 3  is C 1  -C 6  -alkyloxycarbonyl or C 2  -C 6  -alkenyloxycarbonyl, 
     X is oxygen, sulfur or selenium. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In a preferred group of compounds of the formula I or Ia: 
     2) n is zero or one, 
     R 1  is fluorine, chlorine, hydroxyl or C 1  -C 3  -alkoxy, 
     R 2  is C 1  -C 4  -alkyl which is optionally substituted by hydroxyl, C 1  -C 4  -alkoxy or C 1  -C 4  -alkylthio, 
     R 3  is C 1  -C 4  -alkyloxycarbonyl or C 2  -C 4  -alkenyloxycarbonyl, 
     X is oxygen or sulfur. 
     In another preferred group of compounds of the formula I or Ia: 
     3) n is zero or one, 
     R 1  is fluorine, chlorine, methoxy, ethoxy or propoxy, 
     R 2  is methylthiomethyl, ethyl or propyl, or C 1  -C 2  -alkyl which is substituted by hydroxyl or C 1  -C 4  -alkoxy, 
     R 3  is C 1  -C 4  -alkyloxycarbonyl or C 2  -C 4  -alkenyloxycarbonyl, 
     X is oxygen or sulfur. 
     Compounds of the formula I or Ia, as described above, are of very particular importance wherein the said substituents have the following meanings: 
     4) n is zero or one, 
     R 1  is fluorine, chlorine, methoxy or ethoxy, 
     R 2  is methylthiomethyl, ethyl or propyl, or C 1  -C 2  -alkyl which is substituted by hydroxyl or C 1  -C 4  -alkoxy, 
     R 3  is C 1  -C 4  -alkyloxycarbonyl or C 2  -C 4  -alkenyloxycarbonyl, 
     X is oxygen or sulfur. 
     The compound S-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4-dihydroquinoxalin-2(1H)-thione (Ex. 85) is of very particular importance. The compounds of the formulae I and Ia possess an asymmetric carbon atom which is in the so-called S configuration. 
     It has now been found, surprisingly, that the novel compounds possess an antiviral effect which is markedly increased to an extent which was unexpected. It has furthermore been found that the pure enantiomers are markedly easier to dissolve than are the associated racemic compounds. The latter exist as genuine racemates, i.e. as 1:1 compounds of the two enantiomers having individual physical properties. 
     As a consequence of this, the pure enantiomers are markedly better absorbed following oral administration in animal experiments. This is an important prerequisite for the development of a novel pharmaceutical. 
     It is well known that it is of particular importance that high blood levels can be reached in order to achieve a pharmacological or chemotherapeutic effect which is as powerful as possible. 
     In view of the fact that it has not been possible to reach blood levels which are adequate for suppressing viral replication when using many of the virustatic agents which have potential against HIV owing to the low bioavailability of these agents following oral administration, the novel compounds represent antiviral agents of superior activity and consequently represent a therapeutic advance. 
     The pure enantiomers of the compounds of the formulae I and Ia can either be directly prepared by known methods, or in analogy with known methods, or else separated subsequently. 
     The compounds of the formulae I and Ia can be prepared by known methods or by modifications thereof (see, for example, EP-509398-A, Rodd&#39;s Chemistry of Carbon Compounds, S. Coffey, M. F. Ansell (editors); Elsevier, Amsterdam, 1989; vol. IV part IJ, pp. 301 to 311. Heterocyclic Compounds, R. C. Elderfield (editor); Wiley, New York, 1957; vol. 6, pp. 491 to 495). 
     The present invention furthermore relates to a process for preparing compounds of the formulae I or Ia, as explained above in 1) to 4). 
     The process comprises: 
     A) for preparing compounds of the formula I in which X is oxygen and the radicals R 1 , R 2  and R 3  are defined as in 1) to 4), reacting a compound of the formula II, ##STR4##  where the definitions mentioned in 1) to 4) apply to R 1  and R 2 , with a compound of the formula III 
     
         R.sup.3 --Z                                                (III) 
    
     where R 3  has the meanings mentioned above in 1) to 4) and Z is a leaving group such as, for example, chlorine; 
     or comprises: 
     B) for preparing compounds of the formula I, in which X is sulfur and R 1 , R 2  and R 3  are defined as in 1) to 4), comprising the step of reacting a compound of the formula I, where X is oxygen and the definitions mentioned in 1) to 4) apply to R 1 , R 2  and R 3 , with a sulfurization reagent. 
     In the abovementioned method A), the reaction is preferably carried out using a haloformic alkyl or alkenyl ester, a dialkyl or dialkenyl carbonate or a dialkyl or alkenyl dicarbonate. The substituent Z in the formula III is accordingly a suitable leaving group such as, for example, chlorine, bromine or iodine, an alkoxy or alkenyloxy radical, or an alkoxycarbonyloxy or alkenyloxycarbonyloxy group. Z is preferably chlorine. 
     The reaction is expediently carried out in an inert solvent. Examples of suitable solvents are aromatic hydrocarbons, such as toluene or xylene; lower alcohols, such as methanol, ethanol or 1-butanol; ethers, such as tetrahydrofuran or glycol dimethyl ether; dipolar aprotic solvents such as N,N-dimethylformamide, N-methyl-2-pyrrolidone, acetonitrile, nitrobenzene or dimethyl sulfoxide; or mixtures of these solvents. Two-phase systems containing aqueous solutions of bases in the presence of a phase transfer catalyst, such as, for example, benzyltriethylammonium chloride, are also possible. 
     It can be useful for a suitable base, for example an alkali metal or alkaline earth metal carbonate or hydrogen carbonate, such as sodium carbonate, calcium carbonate or sodium bicarbonate; an alkali metal or alkaline earth metal hydroxide, such as potassium hydroxide or barium hydroxide; an alcoholate such as sodium ethoxide or potassium tert-butoxide; an organolithium compound, such as butyllithium or lithium diisopropylamide; an alkali metal or alkaline earth metal hydride, such as sodium hydride or calcium hydride; an alkali metal fluoride, such as potassium fluoride; or an organic base, such as triethylamine, pyridine, 4-methylpyridine or 4-(dimethylamino)pyridine, to be present in order to capture the acid which is liberated during the reaction. 
     In many cases, it is appropriate to add an iodine salt, for example potassium iodide. The reaction is usually carried out at temperatures of between -10° and 160° C., preferably at room temperature. 
     For this reaction, any nucleophilic substituents such as, for example, hydroxyl, mercapto or amino groups, with the exception of the 4 position in compounds of the formula II, must be derivatized in a suitable manner before carrying out the reaction or be provided with customary protective groups, which can subsequently be eliminated, such as, for example, acetyl, benzyl, trityl, tetrahydropyranyl or tert-butoxycarbonyl. 
     2,4-Bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide (Lawesson&#39;s reagent), bis(tricyclohexyltin) sulfide, bis(tri-n-butyltin) sulfide, bis(triphenyltin) sulfide, bis(trimethylsilyl) sulfide or phosphorus pentasulfide may be preferably used as the sulfurization reagent for the reaction as described above in B). 
     The reaction is expediently carried out in an organic solvent or a solvent mixture, at from -10° to 120° C., preferably at from room temperature to 60° C., and as far as possible under anhydrous conditions. Examples of suitable solvents are carbon disulfide, toluene, xylene, pyridine, dichloromethane, 1,2-dichloroethane, tetrahydrofuran, ethyl acetate or butyl acetate. When using the abovementioned tin or silyl sulfides, it is expedient to carry out the sulfurization reaction in the presence of a Lewis acid such as boron trichloride. 
     Owing to its relatively low reactivity, the presence of a carbonyl group in the R 3  radical in the compounds of the formula I does not interfere in this context, so that it is possible to carry out the sulfurization selectively. 
     The quinoxalines of the formula II which are required as starting materials for the described syntheses are either known from the literature or can be prepared by known methods, for example using the methods described in European Patent Application EP-509398-A. 
     The present invention also relates to the compounds as described in 1) to 4) as pharmaceuticals which are preferably used for treating viral diseases, in particular diseases caused by HIV. 
     The present invention furthermore relates to pharmaceuticals which contain at least one novel compound and to the use of the said compounds for preparing pharmaceuticals, preferably for the treatment of viral diseases, in particular for the treatment of diseases which are caused by HIV. 
     The present invention furthermore relates to the use of compounds of the abovementioned formula I or Ia for preparing pharmaceuticals for treating viral diseases. 
     The compounds mentioned and explained in 1) to 4) above are preferred for this use. 
     The novel pharmaceuticals may be administered to a host in need thereof enterally (orally), parenterally (intravenously), rectally, subcutaneously, intramuscularly or locally (topically). 
     They can be administered in the form of solutions, powders (tablets and capsules, including microcapsules), ointments (creams or gels) or suppositories. Pharmaceutically acceptable carriers including customary liquid or solid fillers and extenders, solvents, emulsifiers, lubricants, taste corrigents, dyes and/or buffering substances are suitable for use as auxiliary substances for formulations of this nature. 
     As an expedient dosage, from 0.1 to 10, preferably from 0.2 to 8, mg are administered per kg of body weight once or several times daily. The dosage units employed expediently depend on the relevant pharmacokinetics of the substance or the pharmaceutical preparation which is used. 
     The dosage unit of the novel compounds which is used is, for example, from 1 to 1500 mg, preferably from 50 to 500 mg. 
     The novel compounds may also be administered to a host in need thereof in combination with other antiviral agents such as, for example, nucleoside analogs, protease inhibitors or adsorption inhibitors, immunostimulants, interferons, interleukins and colony-stimulating factors (e.g. GM-CSF, G-CSF and M-CSF). 
     Pure enantiomers are understood to mean those compounds in which the enantiomer ratio is at least 95:5, preferably at least 97:3. 
    
    
     The present invention is explained in more detail by the following examples and by the content of the patent claims. 
     EXAMPLE 1 
     N-(5-Fluoro-2-nitrophenyl)-S-methyl-L-cysteine 
     16.2 g of (-)-S-Methyl-L-cysteine (0.1 mol) are suspended in a mixture of 120 ml of water and 120 ml of acetone in a four-necked flask under N 2 . 30.4 ml (22.2 g) of triethylamine (0.22 mol) are added rapidly while stirring. 15.9 g of 2,4-difluoronitrobenzene (0.1 mol) are added, with further stirring, to the resulting yellow solution. The mixture is heated to reflux for 7.5 hours while stirring (orange-colored solution) and the acetone is then stripped off under reduced pressure on a rotary evaporator; the aqueous residue is transferred to a separating funnel and extracted 2× with approximately 50 ml of methyl tert-butyl ether (MTB ether). This extract is composed, in the main, of 2,4-difluoronitrobenzene and is discarded. The aqueous phase is transferred to a four-necked flask and 150 ml of MTB ether are added to it, after which the mixture is adjusted, while being cooled (&lt;25° C.), to pH 1 with approximately 25 ml of 38% sulfuric acid. The mixture is then stirred thoroughly until clear phases are formed. The ether phase is separated off and the aqueous phase is extracted once again with 50 ml of MTB ether. The extracts are dried over sodium sulfate and evaporated on a rotary evaporator. The yield comprises 27 g of a yellow oil which soon solidifies. M.p. 147° (from water/methanol). 
     MS: chemical ionization, (M+H) +  =275 
     
         ______________________________________Analysis:       Calculated                    Found______________________________________C               43.8%    43.8%H               4.0%     4.1%N               10.2%    10.0%S               11.7%    11.3%______________________________________ 
    
     EXAMPLE 2 
     N-(5-Methoxy-2-nitrophenyl)-S-methyl-L-cysteine 
     27 g of N-(5-fluoro-2-nitrophenyl)-S-methyl-L-cysteine (0.1 mol) from Example 1 are dissolved in 150 ml of absolute methanol in a four-necked flask, and 14.4 g of 95% sodium methoxide (0.25 mmol) are added in portions, within the space of 20 minutes and under argon, to this solution while stirring well and while cooling by means of an ice bath. The mixture is then heated to reflux for 2 hours while stirring. TLC monitoring then indicates that the reaction is complete. 
     Most of the methanol is stripped off under reduced pressure on a rotary evaporator. 200 ml of ice water are added to the residue and this mixture is adjusted to a pH of 1 with approximately 25 ml of 38% sulfuric acid and then thoroughly stirred with 150 ml of MTB ether. The ether phase is separated off and the aqueous phase is extracted once again with 30 ml of MTB ether and subjected to rotary evaporation under reduced pressure. 
     Yield: 21.5 g of brown-red oil which slowly crystallizes. 
     MS: chemical ionization, (M+H) +  =287 
     HPLC: 99.3% of S-enantiomer 
     
         ______________________________________Analysis:       Calculated                    Found______________________________________C               46.2%    47.3%H               4.9%     5.6%N               9.8%     9.1%S               11.1%    10.6%______________________________________ 
    
     EXAMPLE 3 
     S-6-methoxy-3-(methylthiomethyl)-3,4-dihydroquinoxalin-2(1H)-one 
     20.7 g of the compound from Example 2 (0.065 mol) are dissolved in 250 ml of methanol and hydrogenated under argon with 0.5 ml of glacial acetic acid and approximately 20 g of Raney nickel under standard pressure and at room temperature. The hydrogenation is complete when TLC is no longer able to detect any starting material. The mixture is filtered with suction, while being overlaid with nitrogen, and the filter residue is then washed with 100 ml of methanol. 
     The filter residue, including the catalyst, is thoroughly stirred, at from 45° to 50° C., with dimethylformamide (DMF), while being overlaid with nitrogen, and this mixture is then once again filtered with suction through a clarifying layer. The product-containing DMF solution is allowed to run directly into 1 l of ice water which is being stirred and to which 2 g of ascorbic acid have been added as an antioxidant. During this procedure, the product results in the form of pale yellow crystals. These are filtered off with suction, washed with approximately 2 l of water then with 500 ml of ethanol and then with 300 ml of pentane, and dried over phosphorus pentoxide. 
     The yield is 10.8 g; a further 1.3 g can be obtained by concentrating the filtrate. 
     M.p. from 186° to 187° C., yellow-grayish solid. 
       1  H-NMR (200 MHz, d 6  -DMSO): δ=2.08 (s, 3H, SCH 3 ), 2.75 (dq AB , 2H, --CH 2  --S), 3.65 (s, 3H, MeO), 3.95 (m, 1H, CH), 6.05 (br, s, NH), 6.1-6.7 (m, 3H, aromatics), 10.15 (s, 1H, amide). 
     MS: chemical ionization, (M+H) +  =239 
     HPLC: 97.5% purity, 98.2% of the S-enantiomer 
     Optical rotation:  α! D   22  =-42° (c=1 in acetone) 
     
         ______________________________________Analysis:       Calculated                    Found______________________________________C               55.5%    55.2%H               5.9%     5.8%N               11.8%    11.7%S               13.4%    13.3%______________________________________ 
    
     The following are obtained in an analogous manner: 
     EXAMPLE 4 
     S-6-Ethoxy-3-(methylthiomethyl)-3,4-dihydroquinoxalin-2(1H)-one 
     Obtained from the compound of Example 1 using lithium ethoxide in ethanol and carrying out reduction and ring closure in analogy with Example 2. 
     MS: chemical ionization, (M+H) +  =253 
       1  H-NMR (200 MHz, d 6  -DMSO): ethoxy group δ=1.27 (t, 3H), 3.87 (q, 2H) 
     EXAMPLE 5 
     S-3-(Methylthiomethyl)-6-propoxy-3,4-dihydroquinoxalin-2(1H)-one 
     Obtained from the compound of Example 1 using sodium propoxide in propanol. 
     M.p. resin, MS: chemical ionization, (M+H) +  =267 
       1  H-NMR (200 MHz, d 6  -DMSO): propoxy group δ=0.95 (t, 3H), 1.67 (q, 2H), 3.79 (t, 2H) 
     EXAMPLE 6 
     S-3-(Methylthiomethyl)-3,4-dihydroquinoxalin-2(1H)-one 
     Obtained by using 2-fluoronitrobenzene in place of 2,4-difluoronitrobenzene in Example 1. 
     M.p. 109° C., MS: chemical ionization, (M+H) +  =208 
     EXAMPLE 7 
     S-6-Fluoro-3-(methylthiomethyl)-3,4-dihydroquinoxalin-2(1H)-one 
     Obtained by direct further use of the compound from Example 1 in reduction and ring closure reactions as in Example 3. 
     M.p. 149° C., MS: chemical ionization, (M+H) +  =243 
     EXAMPLE 8 
     S-6-Chloro-3-(methylthiomethyl)-3,4-dihydroquinoxalin-2(1H)-one 
     Obtained by using 2,4-dichloronitrobenzene in place of 2,4-difluoronitrobenzene in Example 1 and using sodium hydroxide and glycol monomethyl ether at reflux temperature. 
     M.p. 149° C., MS: chemical ionization, (M+H) +  =243 
     When other amino acids are used, for example, the corresponding compounds of the formula II, in which the  lacuna! substituent of the amino acid employed becomes the substituent R 2  in formula II, can be obtained in an analogous manner to that described in Examples 1 to 8: 
     
                       TABLE 1______________________________________ ##STR5##Example No.      R.sup.1.sub.n                 R.sup.2     M.p. °C.______________________________________ 9         H (n = 0)  C.sub.2 H.sub.5                             Oil10         H (n = 0)  C.sub.3 H.sub.7                             Resin11         H (n = 0)  C.sub.4 H.sub.9                             Oil12         H (n = 0)  HOCH.sub.2   8213         6-Cl       C.sub.2 H.sub.5                             12014         6-Cl       C.sub.3 H.sub.7                             75-7715         6-Cl       C.sub.4 H.sub.9                             Oil16         6-F        C.sub.2 H.sub.5                              9317         6-F        C.sub.3 H.sub.7                             Resin18         6-F        HOCH.sub.2  13419         6-CH.sub.3 O                 C.sub.2 H.sub.5                             Oil20         6-CH.sub.3 O                 C.sub.3 H.sub.7                             13821         6-CH.sub.3 O                 C.sub.4 H.sub.922         6-CH.sub.3 O                 HOCH.sub.2  125 decomp.23         6-CH.sub.3 O                 CH.sub.3 CH(OH)                             15624         6-CH.sub.3 O                 CH.sub.3 OCH.sub.2                             16725         6-C.sub.2 H.sub.5 O                 C.sub.2 H.sub.526         6-C.sub.2 H.sub.5 O                 C.sub.3 H.sub.727         6-C.sub.2 H.sub.5 O                 CH.sub.3 OCH.sub.228         6-C.sub.3 H.sub.7 O                 C.sub.2 H.sub.5 28a       6-OH       CH.sub.3 SCH.sub.2                             146______________________________________ 
    
     EXAMPLE 29 
     S-4-Isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4-dihydroquinoxalin-2(1H)-one 
     11.9 g (0.05 mol) of the compound from Example 3 are suspended in 300 ml of methylene chloride under nitrogen. 7.0 g of 4-methylpyridine (0.075 mol), as base, are added rapidly while stirring. 60 ml of a 1 molar solution of isopropyl chloroformate in toluene (0.06 mol) are then added dropwise at room temperature within the space of 30 minutes. During this procedure, the suspension slowly goes into solution. Monitoring by TLC indicates that the reaction is complete after from 4 to 6 hours at room temperature. The solution is acidified with 2N sulfuric acid, the organic phase is separated off, and the aqueous phase is extracted once more with 50 ml of methylene chloride. After the solvents have been evaporated off under reduced pressure, a semi-solid product remains which is recrystallized from diisopropyl ether while stirring. 
     Yield: 15.0 g, m.p. 115° C. 
       1  H-NMR (200 MHz, d 6  -DMSO): δ=1.3 (2d, J=7 Hz, 6H, 2 isopropyl-CH 3 ), 2.1 (s, 3H, SCH 3 ), 2.35+2.7 (dq AB , 2H, --CH 2  --S), 3.73 (s, 3H, MeO), 4.87 (q, 1H, CH), 4.97 (m, J=7 Hz, 1H, isopropyl-CH), 6.7-7.25 (m, 3H, aromatics), 10.65 (s, 1H, amide). 
     MS: chemical ionization, (M+H) +  =325 
     HPLC: 98% purity, 99.9% of S-enantiomer 
     Optical rotation:  α! D   22  =39° (c=1 in methanol) 
     
         ______________________________________Analysis:       Calculated                    Found______________________________________C               55.6%    55.5%H               6.2%     5.8%N               8.6%     8.4%S               9.8%     9.7%______________________________________ 
    
     When, for example, compounds of the formula II, as mentioned, for example, in Examples 3-28, are used, the following compounds of the formula I in which X═O can be obtained in an analogous manner to that described in Example 29 by reaction with the corresponding compounds of the formula III: 
     
                       TABLE 2______________________________________ ##STR6##Ex-am-ple                                     M.p.No.  R.sup.1.sub.n         R.sup.2     R.sup.3       °C.______________________________________30   H (n = 0)         C.sub.2 H.sub.5                     COOCH(CH.sub.3).sub.2                                   16331   H (n = 0)         C.sub.3 H.sub.7                     COOCH(CH.sub.3).sub.2                                   11732   H (n = 0)         C.sub.4 H.sub.9                     COOCH(CH.sub.3).sub.2                                   12033   H (n = 0)         HOCH.sub.2  COOCH(CH.sub.3).sub.234   H (n = 0)         CH.sub.3 SCH.sub.2                     COOCH(CH.sub.3).sub.2                                   11935   6-Cl     C.sub.2 H.sub.5                     COOCH(CH.sub.3).sub.2                                   145-                                   14736   6-Cl     C.sub.3 H.sub.7                     COOCH(CH.sub.3).sub.237   6-Cl     C.sub.4 H.sub.9                     COOCH(CH.sub.3).sub.238   6-Cl     CH.sub.3 SCH.sub.2                     COOCH(CH.sub.3).sub.2                                   10539   6-F      C.sub.2 H.sub.5                     COOCH(CH.sub.3).sub.2                                   123-                                   12540   6-F      C.sub.3 H.sub.7                     COOCH(CH.sub.3).sub.2                                   11041   6-F      C.sub.4 H.sub.9                     COOCH(CH.sub.3).sub.242   6-F      CH.sub.3 SCH.sub.2                     COOCH(CH.sub.3).sub.2                                   13643   6-CH.sub.3 O         C.sub.2 H.sub.5                     COOCH(CH.sub.3).sub.2                                   Oil44   6-CH.sub.3 O         C.sub.3 H.sub.7                     COOCH(CH.sub.3).sub.2                                   15345   6-CH.sub.3 O         C.sub.4 H.sub.9                     COOCH(CH.sub.3).sub.246   6-CH.sub.3 O         HOCH.sub.2  COOCH(CH.sub.3).sub.2                                   Resin47   6-CH.sub.3 O         CH.sub.3 CH(OH)                     COOCH(CH.sub.3).sub.2                                   Resin48   6-CH.sub.3 O         CH.sub.3 OCH.sub.2                     COOCH(CH.sub.3).sub.2                                    9849   6-C.sub.2 H.sub.5 O         C.sub.2 H.sub.5                     COOCH(CH.sub.3).sub.250   6-C.sub.2 H.sub.5 O         C.sub.3 H.sub.7                     COOCH(CH.sub.3).sub.251   6-C.sub.2 H.sub.5 O         CH.sub.3 OCH.sub.2                     COOCH(CH.sub.3).sub.252   6-C.sub.2 H.sub.5 O         CH.sub.3 SCH.sub.2                     COOCH(CH.sub.3).sub.2                                   11253   6-C.sub.3 H.sub.7 O         C.sub.2 H.sub.5                     COOCH(CH.sub.3).sub.254   6-C.sub.3 H.sub.7 O         CH.sub.3 SCH.sub.2                     COOCH(CH.sub.3).sub.2                                   10555   H (n = 0)         C.sub.2 H.sub.5                     COOC(CH.sub.3)CH.sub.256   H (n = 0)         CH.sub.3 SCH.sub.2                     COOC(CH.sub.3)CH.sub.257   6-Cl     C.sub.2 H.sub.5                     COOC(CH.sub.3)CH.sub.2                                   14358   6-Cl     C.sub.2 H.sub.5                     COOCH.sub.2 CHCH.sub.2                                   122-                                   12459   6-Cl     CH.sub.3 SCH.sub.2                     COOC(CH.sub.3)CH.sub.2                                   18260   6-Cl     CH.sub.3 SCH.sub.2                     COOC.sub.3 H.sub.7                                    6861   6-Cl     CH.sub.3 SCH.sub.2                     COOC.sub.2 H.sub.5                                   14362   6-F      C.sub.2 H.sub.5                     COOC(CH.sub.3)CH.sub.2                                   12563   6-F      C.sub.3 H.sub.7                     COOC(CH.sub.3)CH.sub.264   6-F      CH.sub.3 SCH.sub.2                     COOC(CH.sub.3)CH.sub.265   6-CH.sub.3 O         C.sub.2 H.sub.5                     COOC(CH.sub.3)CH.sub.266   6-CH.sub.3 O         C.sub.3 H.sub.7                     COOC(CH.sub.3)CH.sub.267   6-CH.sub.3 O         CH.sub.3 OCH.sub.2                     COOC(CH.sub.3)CH.sub.268   6-CH.sub.3 O         CH.sub.3 SCH.sub.2                     COOC(CH.sub.3)CH.sub.2                                   15269   6-CH.sub.3 O         CH.sub.3 SCH.sub.2                     COOCH.sub.2 CH(CH.sub.3)C.sub.2 H.sub.570   6-C.sub.2 H.sub.5 O         C.sub.2 H.sub.5                     COOC(CH.sub.3)CH.sub.271   6-C.sub.2 H.sub.5 O         C.sub.3 H.sub.7                     COOC(CH.sub.3)CH.sub.272   6-C.sub.2 H.sub.5 O         CH.sub.3 OCH.sub.2                     COOC(CH.sub.3)CH.sub.273   6-C.sub.2 H.sub.5 O         CH.sub.3 SCH.sub.2                     COOC(CH.sub.3)CH.sub.274   H (n = 0)         C.sub.2 H.sub.5                     COOC.sub.2 H.sub.575   H (n = 0)         C.sub.3 H.sub.7                     COOC.sub.2 H.sub.576   H (n = 0)         CH.sub.3 SCH.sub.2                     COOC.sub.2 H.sub.577   6-Cl     C.sub.2 H.sub.5                     COOC.sub.2 H.sub.578   6-F      C.sub.2 H.sub.5                     COOC.sub.2 H.sub.5                                   11679   6-F      CH.sub.3 SCH.sub.2                     COOC.sub.2 H.sub.580   6-CH.sub.3 O         C.sub.2 H.sub.5                     COOC.sub.2 H.sub.581   6-CH.sub.3 O         CH.sub.3 OCH.sub.2                     COOC.sub.2 H.sub.582   6-CH.sub.3 O         CH.sub.3 SCH.sub.2                     COOC.sub.2 H.sub.583   6-C.sub.2 H.sub.5 O         C.sub.2 H.sub.5                     COOC.sub.2 H.sub.584   6-C.sub.2 H.sub.5 O         CH.sub.3 SCH.sub.2                     COOC.sub.2 H.sub.584a  6-OH     CH.sub.3 SCH.sub.2                     COOCH(CH.sub.3).sub.2                                   18284b  6-OH     C.sub.2 H.sub.5                     COOCH(CH.sub.3).sub.2                                   20184c  6-Cl     CH.sub.3    COOC.sub.2 H.sub.5                                   15184d  6-Cl     C.sub.4 H.sub.9                     COOC(CH.sub.3)CH.sub.2                                   15884e  6-Cl     CH.sub.3 SCH.sub.2                     COOC.sub.2 H.sub.5                                   14384f  6-Cl     CH.sub.3 SCH.sub.2                     COOC.sub.3 H.sub.7                                    6884g  6-CH.sub.3 O         CH.sub.3 SCH.sub.2                     COOCH(CH.sub.3)C.sub.2 H.sub.5                                    8684h  6-CH.sub.3 O         CH.sub.3 SCH.sub.2                     COOCH.sub.2 CH(CH.sub.3).sub.2                                    6084i  6-F      CH.sub.3    COOCH(CH.sub.3).sub.2                                   15184j  6-F      C.sub.2 H.sub.5                     COOCH(CH.sub.3)C.sub.2 H.sub.5                                   Resin84k  6-F      C.sub.2 H.sub.5                     COOCH.sub.3    5084l  6-F      C.sub.2 H.sub.5                     COOC.sub.4 H.sub.9                                    9284m  6-F      C.sub.2 H.sub.5                     COOCH.sub.2 CH(CH.sub.3).sub.2                                    9084n  6-F      CH.sub.2 OH COOCH(CH.sub.3).sub.2                                   Resin84o  6-F      CH.sub.3 OCH.sub.2                     COOCH(CH.sub.3).sub.2                                   114______________________________________ 
    
     EXAMPLE 85 
     S-4-Isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4-dihydroquinoxalin-2(1H)-thione 
     16.1 g of the compound from Example 29 (0.05 mol) are dissolved in 200 ml of dry dimethoxyethane, and 13 g of finely powdered phosphorus pentasulfide (0.06 mol) are added to this solution, under argon and while stirring, and the mixture is then stirred at room temperature. After 24 hours, the reaction is still not complete so that a further 4 g of phosphorus pentasulfide are added. After having been incubated at room temperature for 24 hours, the mixture is stirred for a further 3 hours at 30° C. The mixture is then filtered with suction through a clarifying layer in order to separate off solids, which are then washed with dimethoxyethane. The collected filtrates are evaporated under reduced pressure. The dark oil which remains is taken up in 250 ml of MTB ether and this solution is thoroughly stirred with 200 ml of a saturated solution of sodium hydrogen carbonate. The phases are separated and the aqueous phase is extracted once again with 20 ml of MTB ether. The organic extracts are dried over magnesium sulfate or sodium sulfate and subjected to rotary evaporation. 
     The yellow-brown oil which remains is dissolved in 30 ml of hot diisopropyl ether. It crystallizes out when the solution is cooled while being stirred. The crystals which have precipitated are washed with a little diisopropyl ether and n-pentane and dried in a desiccator. 
     Yield 91.4 g, m.p. 103° C. 
       1  H-NMR (200 MHz, d 6  -DMSO): δ=1.27 (2d, J=7 Hz, 6H, 2 isopropyl-CH 3 ), 2.1 (s, 3H, SCH 3 ), 2.34+2.79 (dq AB , 2H, --CH 2  --S), 3.75 (s, 3H, MeO), 4.97 (m, J=7 Hz, 1H, isopropyl-CH), 5.25 (q, 1H, CH), 6.75-7.3 (m, 3H, aromatics), 12.73 (s, 1H, thioamide). 
     MS: chemical ionization, (M+H) +  =341 
     HPLC. 99.6% purity, 99.4% of S-enantiomer 
     Optical rotation:  α! D   22  =18° (c=1 in methanol) 
     
         ______________________________________Analysis:       Calculated                    Found______________________________________C               52.9%    52.9%H               5.9%     5.3%N               8.4%     8.3%S               18.8%    18.6%______________________________________ 
    
     When, for example, compounds of the formula I in which X═O, as mentioned, for example, in Examples 30 to 84, are used, the following compounds of the formula I in which X═S can be obtained in an analogous manner to that described in Example 85 by reaction with the corresponding sulfurization reagents: 
     
                       TABLE 3______________________________________ ##STR7##Example                                 M.p.No.    R.sup.1.sub.n           R.sup.2     R.sup.3     °C.______________________________________ 86    H (n = 0)           C.sub.2 H.sub.5                       COOCH(CH.sub.3).sub.2                                   114 87    H (n = 0)           C.sub.3 H.sub.7                       COOCH(CH.sub.3).sub.2                                   128 88    H (n = 0)           C.sub.4 H.sub.9                       COOCH(CH.sub.3).sub.2                                    78 89    H (n = 0)           HOCH.sub.2  COOCH(CH.sub.3).sub.2 90    H (n = 0)           CH.sub.3 SCH.sub.2                       COOCH(CH.sub.3).sub.2                                   Oil 91    6-Cl     C.sub.2 H.sub.5                       COOCH(CH.sub.3).sub.2                                   161 92    6-Cl     C.sub.3 H.sub.7                       COOCH(CH.sub.3).sub.2 93    6-Cl     C.sub.4 H.sub.9                       COOCH(CH.sub.3).sub.2 94    6-Cl     CH.sub.3 SCH.sub.2                       COOCH(CH.sub.3).sub.2                                   124 95    6-F      C.sub.2 H.sub.5                       COOCH(CH.sub.3).sub.2                                    93 96    6-F      C.sub.3 H.sub.7                       COOCH(CH.sub.3).sub.2                                    60 97    6-F      C.sub.4 H.sub.9                       COOCH(CH.sub.3).sub.2 98    6-F      CH.sub.3 SCH.sub.2                       COOCH(CH.sub.3).sub.2                                   122 99    6-CH.sub.3 O           C.sub.2 H.sub.5                       COOCH(CH.sub.3).sub.2                                    74100    6-CH.sub.3 O           C.sub.3 H.sub.7                       COOCH(CH.sub.3).sub.2                                   140101    6-CH.sub.3 O           C.sub.4 H.sub.9                       COOCH(CH.sub.3).sub.2102    6-CH.sub.3 O           HOCH.sub.2  COOCH(CH.sub.3).sub.2103    6-CH.sub.3 O           CH.sub.3 CH(OH)                       COOCH(CH.sub.3).sub.2104    6-CH.sub.3 O           CH.sub.3 OCH.sub.2                       COOCH(CH.sub.3).sub.2                                   137105    6-C.sub.2 H.sub.5 O           C.sub.2 H.sub.5                       COOCH(CH.sub.3).sub.2106    6-C.sub.2 H.sub.5 O           C.sub.3 H.sub.7                       COOCH(CH.sub.3).sub.2107    6-C.sub.2 H.sub.5 O           CH.sub.3 OCH.sub.2                       COOCH(CH.sub.3).sub.2108    6-C.sub.2 H.sub.5 O           CH.sub.3 SCH.sub.2                       COOCH(CH.sub.3).sub.2                                   Oil109    6-C.sub.3 H.sub.7 O           C.sub.2 H.sub.5                       COOCH(CH.sub.3).sub.2110    6-C.sub.3 H.sub.7 O           CH.sub.3 SCH.sub.2                       COOCH(CH.sub.3).sub.2                                   Resin111    H (n = 0)           C.sub.2 H.sub.5                       COOC(CH.sub.3)CH.sub.2112    H (n = 0)           CH.sub.3 SCH.sub.2                       COOC(CH.sub.3)CH.sub.2113    6-Cl     C.sub.2 H.sub.5                       COOC(CH.sub.3)CH.sub.2                                   170114    6-Cl     C.sub.2 H.sub.5                       COOCH.sub.2 CHCH.sub.2                                   123115    6-Cl     CH.sub.3 SCH.sub.2                       COOC(CH.sub.3)CH.sub.2                                   128116    6-Cl     CH.sub.3 SCH.sub.2                       COOC.sub.3 H.sub.7117    6-Cl     CH.sub.3 SCH.sub.2                       COOC.sub.2 H.sub.5118    6-F      C.sub.2 H.sub.5                       COOC(CH.sub.3)CH.sub.2119    6-F      C.sub.3 H.sub.7                       COOC(CH.sub.3)CH.sub.2120    6-F      CH.sub.3 SCH.sub.2                       COOC(CH.sub.3)CH.sub.2121    6-CH.sub.3 O           C.sub.2 H.sub.5                       COOC(CH.sub.3)CH.sub.2122    6-CH.sub.3 O           C.sub.3 H.sub.7                       COOC(CH.sub.3)CH.sub.2123    6-CH.sub.3 O           CH.sub.3 OCH.sub.2                       COOC(CH.sub.3)CH.sub.2124    6-CH.sub.3 O           CH.sub.3 SCH.sub.2                       COOC(CH.sub.3)CH.sub.2                                   152125    6-CH.sub.3 O           CH.sub.3 SCH.sub.2                       COOCH.sub.2 CH(CH.sub.3)                       C.sub.2 H.sub.5126    6-C.sub.2 H.sub.5 O           C.sub.2 H.sub.5                       COOC(CH.sub.3)CH.sub.2127    6-C.sub.2 H.sub.5 O           C.sub.3 H.sub.7                       COOC(CH.sub.3)CH.sub.2128    6-C.sub.2 H.sub.5 O           CH.sub.3 OCH.sub.2                       COOC(CH.sub.3)CH.sub.2129    6-C.sub.2 H.sub.5 O           CH.sub.3 SCH.sub.2                       COOC(CH.sub.3)CH.sub.2130    H (n = 0)           C.sub.2 H.sub.5                       COOC.sub.2 H.sub.5131    H (n = 0)           C.sub.3 H.sub.7                       COOC.sub.2 H.sub.5132    H (n = 0)           CH.sub.3 SCH.sub.2                       COOC.sub.2 H.sub.5133    6-Cl     C.sub.2 H.sub.5                       COOC.sub.2 H.sub.5134    6-F      C.sub.2 H.sub.5                       COOC.sub.2 H.sub.5                                   Resin135    6-F      CH.sub.3 SCH.sub.2                       COOC.sub.2 H.sub.5136    6-CH.sub.3 O           C.sub.2 H.sub.5                       COOC.sub.2 H.sub.5137    6-CH.sub.3 O           CH.sub.3 OCH.sub.2                       COOC.sub.2 H.sub.5138    6-CH.sub.3 O           CH.sub.3 SCH.sub.2                       COOC.sub.2 H.sub.5139    6-C.sub.2 H.sub.5 O           C.sub.2 H.sub.5                       COOC.sub.2 H.sub.5140    6-C.sub.2 H.sub.5 O           CH.sub.3 SCH.sub.2                       COOC.sub.2 H.sub.5140a   6-OH     CH.sub.3 SCH.sub.2                       COOCH(CH.sub.3).sub.2                                   113140b   6-OH     C.sub.2 H.sub.5                       COOCH(CH.sub.3).sub.2                                   Resin140c   6-Cl     CH.sub.3    COOCH.sub.2 CHCH.sub.2                                   144140d   6-Cl     CH.sub.3    COOC(CH.sub.3)CH.sub.2                                   149140e   6-Cl     C.sub.4 H.sub.9                       COOC(CH.sub.3)CH.sub.2                                   132140f   6-CH.sub.3 O           CH.sub.3 SCH.sub.2                       COOCH(CH.sub.3)                                    60                       C.sub.2 H.sub.5140g   6-CH.sub.3 O           CH.sub.3 SCH.sub.2                       COOCH.sub.2 CH(CH.sub.3).sub.2                                    89140h   6-F      C.sub.2 H.sub.5                       COOCH.sub.3 146140i   6-F      C.sub.2 H.sub.5                       COOC.sub.4 H.sub.9                                   103140j   6-F      C.sub.2 H.sub.5                       COOCH.sub.2 CH(CH.sub.3).sub.2                                   Resin140k   6-F      C.sub.2 H.sub.5                       COOCH(CH.sub.3)                                    51                       C.sub.2 H.sub.5140l   6-F      CH.sub.3 OCH.sub.2                       COOCH(CH.sub.3).sub.2                                   143______________________________________ 
    
     Activity tests 
     Testing of preparations against HIV in cell culture 
     Description of the method: 
     medium: RMPI, pH 6.8 
     Complete medium additionally contains 20% fetal calf serum and 40 IU/ml recombinant interleukin 2. 
     Cells 
     Lymphocytes, which have been isolated from fresh donor blood by means of Ficoll® gradient centrifugation, are cultured, for 36 hours at 37° C. and under 5% CO 2 , in complete medium which additionally contains 2 g/ml phytohemagglutinin (Wellcome). After 10% DMSO has been added, the cells are frozen at a cell density of 5×10 6  and stored in liquid nitrogen. For the experiment, the cells are thawed, washed in the RPMI medium and cultured for 3 to 4 days in the complete medium. 
     Assay mixture 
     The test preparations were dissolved in DMSO at a concentration of 16.7 mg/ml, and these solutions were diluted with complete medium to a concentration of 1 mg/ml. 0.4 ml of medium was initially introduced into 24-well multiwell plates. After 0.1 ml of the dissolved preparation had been added to the upper row of the plate, a geometric dilution series was produced by transferring 0.1 ml on each occasion. Preparation-free controls contained 0.4 ml of complete medium containing 0.5% DMSO. 
     Lymphocyte cultures having a cell count of 5×10 5  cells/ml were infected by adding a 1/50 volume of the supernatant from HIV-infected lymphocyte cultures. The titer of these culture supernatants was determined by end-point dilution to be 1-5×10 6  infectious units/ml. After having been incubated at 37° C. for 30 min, the infected lymphocytes were centrifuged off and taken up once again in the same volume of medium. 0.6 ml of this cell suspension was added to each of the wells in the test plate. The assay mixtures were incubated at 37° C. for 3 days. 
     Evaluation 
     The infected cell cultures were examined under the microscope for the presence of giant cells, which are indicative of active viral replication in the culture. The lowest preparation concentration at which no giant cells occurred was determined and taken to be the inhibitory concentration against HIV. As a control, the supernatants from the culture plates were assayed for the presence of HIV antigen using an HIV antigen test in accordance with the manufacturer&#39;s (Organon) instructions. 
     Results 
     
                       TABLE 4______________________________________Compound from  T-cell culture assayExample No.    MIC EC.sub.50 (ng/ml)______________________________________ 29            &lt;8 30            &lt;40 31            50 34            &lt;1 35            &lt;80 38            &lt;1 39            8 40            80 42            &lt;8 43            &lt;1 44            &lt;80 52            &lt;8 54            40 57            1 58            10 59            20 60            40 61            2 62            80 68            8 78            &lt;80 84i           80 84j           &lt;80 84l           80 84o           80 85            2 86            1 87            4 88            &lt;40 90            &lt;8 91            2 94            &lt;8 95            2 96            80 98            3 99            &lt;1100            4104            8108            &lt;5110            4113            0.8114            1.6115            1.6124            &lt;8134            8140a           40140b           &lt;80140c           40140d           10140f           8140g           40140h           10140i           10140j           10140k           8140l           8______________________________________ 
    
     Examination of the substances for their ability to inhibit HIV reverse transcriptase 
     The activity of the reverse transcriptase (RT) was determined using a scintillation proximity assay (SPA). 
     The reagent kit for the RT SPA was obtained from Amersham/Buchler (Braunschweig). The RT enzyme (derived from HIV and cloned in E. coli) was obtained from HT Biotechnology Ltd., Cambridge, UK. 
     Assay mixture 
     The test was carried out in accordance with the manufacturer&#39;s (Amersham) methods manual, with the following modifications: 
     Bovine serum albumin was added to the assay buffer to a final concentration of 0.5 mg/ml. 
     The test was carried out in Eppendorf tubes using an assay mixture volume of 100 μl. 
     The manufacturer&#39;s RT concentrate (5000 U/ml) was diluted to an activity of 15 U per ml using 20 mM tris-HCl buffer, pH 7.2, 30% glycerol. 
     The assay mixtures were incubated for 60 min (37° C.). 
     After the reaction had been stopped and &#34;developed&#34; with the bead suspension, 130 μl of assay mixture were transferred into 4.5 ml of 10 mM tris-HCl buffer, pH 7.4, 0.15M NaCl and the tritium activity was measured in a β-counter. 
     Testing the substances 
     In order to carry out a preliminary test of their inhibitory activity, the substances were dissolved in DMSO (stock solution, c=1 mg/ml) and tested when diluted 10 -1 , 10 -2 , 10 -3  etc. in DMSO. 
     In order to determine IC 50  values, the stock solutions of inhibitor were further diluted in 50 mM tris-HCl buffer, pH 8, and tested at suitable concentrations. 
     The concentration associated with 50% inhibition of the enzyme was ascertained from the plot of RT activity against log C inh . 
     The results of the investigation are shown in Table 5. 
     
                       TABLE 5______________________________________         Reverse transcriptaseCompound from assayExample No.   IC.sub.50 (ng/ml)______________________________________ 29           10-100 34           10-100 35           10 38            5 39           20 40           10-100 52           10-100 57           10-100 58           10-100 59           18 60           10 61           10-100 62           92 68           16 78           80 84g          118 84i          170 84j          87 84l          150 85            8 86           11 87           27 90            5 91            4 94           15 96           16 98           12 99           11100           16104           35108            8110           10-100113            6114            7115           10125           15134            3140a          93140b          70140c          110140d          27140f          19140g          17140h           8140i          22140j          15140k          16140l          22______________________________________