4,5-DIHYDROXY- AND 4,5,8-TRIHYDROXY- 9,10-DIHYDRO-9,10-DIOXO-2-ANTHRACENECARBOXYLIC ACID DICARBONATES AND URETHANS HAVING THERAPEUTICAL ACTIVITIES

Abstract: 4,5-Dihydroxy- and 4,5,8-trihydroxy- 9,10-dihydro-9,10-dioxo-2-anthracenecarboxylic acid dicarbonates and urethans having therapeutical activities, a process for the preparation thereof and pharmaceutical compositions containing them.

Description: 4,5-DIHYDROXY- AND ,5 ,8-TRIHYDROXY- 9.10-DIHYDRO-9 ,10- DIOXO-2-ANTHRACENECARBOXYLIC ACID DICARBONATES AND DRETHANS HAVING THERAPEUTICAL ACTIVITIES The present invention relates to 2-anthracenecar- boxylic derivatives of general formula (I) wherein: X is hydrogen or a OCOR group, in which R is as defined below; Y is hydrogen, C,-C 20 alkyl; C,-C, g alkoxyethyl; C,-C,g alkylthioethyl; R is a straight, branched or cyclic C,-C 20 alkoxy, ary- loxy, benzyloxy, 2-phenylethoxy group; R 1R2N, wherein R 1 and R2, which can be the same or different, are se¬ lected from hydrogen; straight, branched or alicyclic C-^-C j - alkyl, phenyl, benzyl, 2-phenylethyl; and to the pharmaceutically acceptable salts thereof. Preferred compounds of the invention are those in which R is selected from: methoxy, ethoxy, propoxy, bu- toxy, benzyloxy, methylamino, ethylamino, propylamino, benzylamino; Y is hydrogen or C,-C 4 alkyl, ethoxyethyl or ethylthioethyl. Exemplifications of pharmaceutically acceptable salts are the salts with alkali or alkaline-earth me¬ tals, such as sodium, potassium, calcium or magnesium salts; and the salts with organic bases, such as etha- nolamine, diethanolamine, N,N-dialkylethanolamine, phenylethylamine, piperazine, morpholine, lysine and the like. Compounds having a 9,10-anthraquinone structure, such as diacetylrhein, are known to have antiarthritic activity (DE 2711493). Italian Patent application n. 21456 A/87 discloses rhein derivatives wherein the hydroxy groups are repla- ced by thio groups. Now it has been found that rhein and 8-hy- droxyrhein carbonic esters and urethans, of formula (I), have a marked inhibitory activity against the en¬ zymes involved in articular- pathology. Particularly, the compounds of the invention proved to have a surpri¬ sing effect on mammal collagenase and elastase activi¬ ties, thus being advantageous in the therapeutical tre¬ atment of arthritic conditions. Said activities are particularly important in the treatment of cartilage pathology as well as in that of collagenous tissues. Among the observed activities, particularly impor¬ tant are the inhibition of free radical formation and the inhibition of spontaneous auto-lysis of cartilages. The compounds of the invention in which R is dif¬ ffeerreenntt ffrroomm NNRR 1R2 are prepared by reacting one compound of formula (II) (ID wherein X 1 is hydrogen or OH and Y is as defined above, with a chlorocarbonate of formula (III) R0C0C1 (III) wherein R is as defined above. Compounds (II) wherein Y is an alkyl, alkoxyethyl or alkylthioethyl group can be prepared by means of conventional esterification methods of compounds (II) in which Y is hydrogen. Compounds (I) in which R is a NR 1R2 group are pre- pared by reacting a compound of formula (II) above with phosgene and subsequently with a compound of formula wherein R1 and R2 are as defined above. Alternatively, compounds (I) wherein R is NR 1R2 are prepared by reacting a compound of formula (II) with a compound of formula R 1R2NOCl, wherein R1 and R2 are as defined above. The compounds of the invention can be used as such or in form of pharmaceutically acceptable salts the¬ reof, in the preparation of medicaments, together with suitable conventional carriers. Examples of solid formulations are tablets, capsu¬ les, pills, or other forms of suitable bio-availabi- lity. Dosages can range from 5 to 500 mg per unit dose, the daily dose depending on the severity of the arthri¬ tic pathology and the patient's conditions, according to the physician judgement. The following Examples further illustrate the in- vention. EXAMPLE 1 Preparation of ,5-bis(methoxycarbonyloxy)-9,10-dihy- dro-9,10-dioxo-2-anthracenecarboxylic acid. 2.84 g (0.01 mole) of acid (I) in 50 ml of anhy¬ drous tetrahydrofuran are placed into a two-necked flask fitted with a thermometer and a dropper with CaCl 2 valve, then 3.03 g (0.03 mole) of anhydrous triethylamine are added. 2.08 g (0.022 mole) of methyl chloroformate dissolved in 5-10 ml of anhydrous tetra¬ hydrofuran are dropped into the stirred mixture, at 5°C. The reaction temperature must be kept below 30°C. When dropping is over (after about 4 hours) the preci¬ pitate is filtered, the solvent is evaporated off under vacuum from the filtrate and the fluid residue is trea¬ ted with water and acidified with diluted HCl to pH 3- 4. The product precipitates and it is dried. Elementary analysis for C,gH-. 9 0-. n theoretical% found% C 57 , 00 56 , 94 H 3 , 02 2 , 98 ' 0 39 , 97 39 , 87 IR in conformity. EXAMPLES 2-7 Following the procedure described in Example 1, the following compounds are obtained: The spectroscopical and elementary analysis data confirm the proposed structures. EXAMPLE 8 Preparation of 4,5,8-tris(methylaminocarbonyloxy)-9,10 dihydro-9,10-dioxo-2-anthracenecarboxylic acid. 2.84 g of acid (I) are suspended in 70 ml of anhy drous tetrahydrofuran. The suspension is cooled to 0 P C it is added with 3.03 g (0.03 mole) of anhydrou triethylamine, then 16 ml of a solution of 20% phosgen in toluene are dropped therein. The reaction proceed for 24 hours, always keeping temperature at about 0°C After that, solvent is evaporated off under vacuum an the obtained bis-chloroformate is directly used to pre pare the urethan. (Chlorofor te formation can be moni tored by T.L.C., using 9:1 tetrahydrofuran/water as th eluent. A small amount of chloroformate is treated wit a t-butylamine excess, then the excess is removed unde vacuum and the residue is dissolved in methanol. Th chromatographic plate can directly be seeded with suc a solution) . The obtained bis-chloroformate is freed from th solvent and suspended in 40 ml of anhydrous tetrahy drofuran at 0 β C. 1.55 g (0.05 mole) of methylamine ar dropped into the suspension, keeping temperature a 0°C. The reaction is immediate. The suspension is fil tered, the filtrate is evaporated under vacuum and th residue is washed with distilled water. The precipitat is filtered, dried and suitably crystallized. Elementary analysis for c ιq H i 4 N 2°8 theoretical% found% C 57,29 57,36 H 3,54 3,52 N 7,02 7,10 IR in conformity. EXAMPLES 9-12 Following the procedure described in Example 8, starting from the appropriate reagents, the following compounds are obtained : The spectroscopical and elementary analysis data confirm the proposed structures. The compounds of Examples 8 and 9 can also be pre¬ pared from the corresponding chloroamides, which react with acid (I). The procedure ' is as follows: 2.84 g (0.01 mole) of acid (I) are suspended in 70 ml of tetrahydrofuran. The suspension is cooled to 0 β C and added with 3.03 g (0.03 mole) of anhydrous triethy- lamine and 0.02 mole of N,N-dialkylchloroamide. The urethan immediately forms, together with a precipitate which is filtered off. The clear solution is evaporated under reduced pressure to obtain a residue which is suitably crystallized. EXAMPLES 13-14 Following the procedure described in Example 8, starting from the appropriate reagents, the following products are obtained: ES.N. X Y R Formula 13 H H CH 3 NH C 21 H 17 N 3°10 14 OCOR B C 2 H 5 NH C^H^O^ The spectroscopical and elementary analysis data confirm the proposed structures. EXAMPLE 15 Preparation of 4,5-dihydroxy-9,10-dihydro-9,10-dioxo-2- anthracenecarboxylic acid butyl ester. 7.4 g (0.02 mole) of 4,5-bis(acetoxy)-9,10-dihy- dro-9,10-dioxo-2-anthracenecarboxylic acid are dissol¬ ved in 150 ml of butanol. Gaseous HC1 is bubbled through the obtained solution until saturation. The re- action mixture is left to react for half an hour at room temperature, then it is heated to 60-70°C for 3 hours, while continuing HC1 bubbling. The desired pro¬ duct precipitates, which is cooled, filtered and cry¬ stallized from ethyl acetate. Elementary analysis for C-igH., -0 g theoretical% found% C 67,05 67,00 H 4,73 4,70 0 28,20 28,27 IR in conformity. EXAMPLES 16-17 Following the procedure described in Example 15, starting from the appropriate reagents, the following compounds are obtained: The spectroscopical and elementary analysis data confirm the proposed structures. EXAMPLE 18 Preparation of 4.S-dihydrox -g^O-dihydro-g^O-dioxo-Σ- anthracenecarboxylic acid ethylthioethyl ester. 7.4 g (0.02 mole) of 4,5-bis(acetyloxy)-9,10-dihy- dro-9,10-dioxo-2-anthracenecarboxylic acid are dis¬ solved in 40 ml of SOCl-. The reaction mixture is left to react for 2 hours under stirring, then the thionyl chloride excess is evaporated off under vacuum, the re¬ sidue is washed with anhydrous benzene and solvent is evaporated off under vacuum. The formed chloride is dissolved in 200 ml of chloroform and the obtained so¬ lution is dropped into a mixture of 2 g (0.02 mole) of triethylamine and 2.2 g (0.02 mole) of 2-ethyl-thio- ethyl alcohol in 40 ml of chloroform, at a temperature of 0°-10 β C. The reaction is almost immediate at room temperature. After that, solvent, is evaporated off un¬ der vacuum, the residue is taken up into 40 ml of ben¬ zene and filtered. The filtrate is treated with 10% NH, and it is left to react for about 12 hours at room temperature. The solution is acidified to pH 5-6 with diluted HC1. A precipitate is obtained which can be filtered, containing the crude product. The crude pro¬ duct is washed with acetone, filtered and purified by silica gel chromatography, using ethyl acetate as the eluent. Elementary analysis for C T Q H I6 0 6 S IR in conformity. Preparation of 4 ,5-bis(metoxycarbonyloxy)-9,10-dihydro- 9,10-dioxo-2-anthracenecarboxylic acid butyl ester. 2.7 g (8 mmoles) of the product of Example 15 are dissolved in 100 ml of anhydrous tetrahydrofuran; the resulting solution is added first with 2.42 g (24 mmo¬ les) of anhydrous triethylamine, then, after cooling to 0°-5°C, with 1.6 g (17 mmoles) of methyl chloroformate. The reaction is complete within 3 hours, keeping room temperature. After that, solvent is evaporated off un¬ der reduced pressure and the residue is washed with acidulated water, the product is filtered, washed and crystallized from ethyl ether. M.p. 200°-202°C. Elementary analysis for C 23 H 20°lo theoretical% found% C 60,52 60,47 H 4,41 4,39 O 35,05 35,00 IR in conformity. EXAMPLES 20-35 Following the procedure described in Example 19, starting from the appropriate reagents, the following compounds are obtained: The procedure of Example 8 is followed, but using 2.7 g (8 mmoles) of the product of Example 15, 2.42 g (24 mmoles) of triethylamine and about 14 ml of a 20% C0C1 2 solution in toluene to prepare bis-chloroformate. 1.24 g (40 mmoles) of methylamine are used to pre¬ pare the final product. Elementary analysis for C 23 H 22 N 2° 8 theoretical% found% C 60,78 60,82 H 4,88 4,89 N 6,16 6,23 EXAMPLES 37-52 Following the procedure described in Example 36, starting from the appropriate reagents, the following compounds are obtained: The spectroscopical and elementary analysis data confirm the proposed structures.

Claims: CLAIMS 1. Compounds of general formula (I) wherein: X is hydrogen or a OCOR group, in which R is as defined below; Y is hydrogen, C,-C 20 alkyl; C,-C,g alkoxyethyl; C,-C, g alk lthioeth l R is a straight, branched or cyclic C,-C 20 alkoxy, ary- loxy, benzyloxy, 2-phenylethoxy group; R 1R2N, wherein R 1 and R2, which can be the same or different, are se¬ lected from hydrogen; straight, branched or alicyclic C,-C, 0 alkyl, phenyl, benzyl, 2-phenylethyl; and the pharmaceutically acceptable salts thereof. 2. Compounds of claim 1, wherein Y is hydrogen or C,-C 4 alkyl, ethoxyethyl or ethylthioethyl; R is methoxy, ethoxy, propoxy, butoxy, benzyloxy, methylamino, ethylamino, propylamino, benzylamino; and, when Y is hydrogen, the salts thereof with pharmaceutically acceptable organic bases and metals. 3. A process for the preparation of the compounds of claims 1 and 2, which process comprises reacting a com¬ pound of formula (II) wherein X 1 is hydrogen or OH and Y is as defined in claim 1, with a chlorocarbonate of formula (III) R0C0C1 (III) wherein R is as defined in claim 1. 4. A process for the preparation of the compounds of claim 1, which process comprises reacting a compound of formula (II) with phosgene and subsequently with a compound of for- R. mula N 1 wherein R1 and R2 are as defined in claim 1. κ 2 5. The use of the compounds of claims 1-2 as therapeu¬ tical agents. 6. Pharmaceutical compositions containing the compounds of claims 1-2 as the active ingredients. 7. The use of the compounds of claims 1-2 for the pre¬ paration of a medicament having antiarthritic activity.

Inventors: MIAN MAURIZIO, ROSINI SERGIO, MIAN, MAURIZIO, ROSINI, SERGIO
Applicants: GENTILI IST SPA, ISTITUTO GENTILI S.P.A.
Application year: 1991
Main classification: C07C323
IPC codes: A61K31, A61P29, C07C68, C07C69, C07C271, C07C319, C07C323