NOVEL PILOCARPINE DERIVATIVES AND PROCESS FOR THEIR PREPARATION

Abstract: The object of the invention are pharmaceutically useful bispilocarpic acid ester derivatives of general formula (I), wherein Y is -C(=O)-R, wherein R is C1-C4-alkyl, C3-C6-cycloalkyl or phenyl, whereby W is a group of formula (Ia), or Y is a group of formula (Ib), whereby W is R', which is C1-C4-alkyl or C3-C6-cycloalkyl, wherein Y has the meaning given above, and A is a direct bond or a methylene group, which can be substituted with hydroxy, the group Y-O- wherein Y has the meaning given, or with one or two methyl groups, and B is a direct bond, methylene or ethylene, and their acid addition salts.

Description: Novel pilocarpine derivatives and process for their preparation The present invention relates to novel pilocarpine prodrug compounds useful for the treatment of glaucoma, and specifically to bispilocarpic acid esters, processes for the preparation of the said novel compounds, pharmaceuti¬ cal compositions containing the novel compounds and their use. (+)-pilocarpine, (3S-cis)-3-ethyldihydro-4-[ (1-methyl-lH- imidazol-5-yl)methyl]-2(3H)-furanone, is a drug which is used for the treatment of glaucoma, which lowers the ocular pressure by increasing the flow of chamber fluid from the eye. The intraocular pressure reducing effect of pilocar¬ pine is based on the ciliary muscle contracting effect of the drug widening the angle of the anterior chamber which is important from the viewpoint of the outflow of the chamber fluid and the outflow of the fluid is facilitated. The reduction of the intraocular pressure is, however, not the only effect of pilocarpine in the eye. When the drug concentration is sufficiently high, the contracting effect of pilocarpine on the ciliary muscle is increased, resul¬ ting in the adaptation of the ocular lens for seeing at close distance. It is then difficult for the patient to accommodate the eye for seeing at a greater distance, which is inconvenient for the patient. Pilocarpine also causes the iris of the eye to contract, the pupil of the eye decreasing considerably. Besides these effects on the eye which are unnecessary from a medical point of view and unpleasant for the patient, pilocarpine may cause side effects outside the eye. Such effects are i.a. increased salivation and bradycardia. Conventionally glaucoma patients administer pilocarpine locally as eyedrops. Administered in such a manner, however, only about 1 % of the pilocarpine dose is absor¬ bed by the eye and about 70 % in the blood stream. The low absorption rate of pilocarpine in the eye is due to three major factors: 1) the drop is quickly flushed away from the surface of the eye 2) the rapid absorption of pilocarpine into the blood stream through the conjunctiva of the inner surface of the eyelid 3) the poor corneal penetration capability of pilo¬ carpine. Pilocarpine is absorbed into the eye through the cornea. In the cornea it is first absorbed in the dense epithelium layer on the eye surface containing cell membrane lipids (fats) in abundance. However, pilocarpine is not very fat soluble wherefore it penetrates relatively little into the corneal epithelium. The corneal epithelium functions simultaneously as a film restricting the absorption of pilocarpine, and as a storage, which delivers pilocarpine through the aqueous stroma and endothelium of the cornea into the fluid of the anterior chamber. From the chamber fluid pilocarpine has easy access to its action site, the ciliary muscle. The duration of the effect of pilocarpine in the eye is substantially reduced by its partial conver¬ sion to inactive pilocarpic acid and the rapid departure of pilocarpine from the eye through the chamber fluid circula¬ tion and the blood circulation of the iris. The low absorption into the inner parts of the eye and the short duration of action of pilocarpine administered into the eye cause difficulties in drug treatment. In order to improve the action of the drug and increase its duration of action, pilocarpine must be used in relatively big doses. From this follows that high pilocarpine levels are obtained in the chamber fluid, in the iris and the ciliary muscle which lead to a strong contraction of the pupil and adapta¬ tion of the eye to seeing at close distance. Increasing the dose of pilocarpine is, in addition, a relatively ineffec¬ tive way of prolonging the action of the drug, the drug being of the type that is rapidly excreted from the eye, and thus pilocarpine eyedrops are administered 3 to 8 times daily depending on the patient. Administration of eyedrops so frequently is inconvenient from the point of view of the patient, especially when the administration of the drops is always followed by side effects in the eye. The use of big doses also increases the amount of pilocarpine absorbed in the blood circulation and thus also the risk for other side effects. Efforts have been aimed at solving the afore said disad¬ vantages relating to the poor absorption of pilocarpine by using pilocarpine prodrug derivatives which absorb better into the corneal epithelium. Such derivatives have to be more fat soluble than pilocarpine in order to improve absorption. In addition, they have to degrade as complete¬ ly as possible in the corneal epithelium to liberate the pharmaceutically effective pilocarpine and the ineffective pro-moiety. The degree of degradation in the cornea is dependant on the residence time of the derivative in the corneal epithelium and its degradation rate therein. The residence time of the derivative in the epithelium is increased with increased lipophilicity and decreased diffusion coefficient. Up to now two kinds of prodrug derivatives of pilocarpine have been developed. Bodor discloses in the US-patent 4,061,722 pilocarpine prodrugs based on quaternary am¬ monium compounds. Bundgaard et al. have disclosed in EP- patent application 0 106 541 pilocarpic acid diesters, by means of which improved ocular absorption has been reach¬ ed. The said pilocarpic diesters are, however, associated with certain disadvantages, such as poor aqueous solubility and eye irritation. Also, a great number of undesirable side products are released from the diesters as compared to the active agent itself, pilocarpine. The present invention relates to novel bispilocarpic acid esters, i.e. bispilocarpates, by means of which the aforementioned disadvantages may largely be eliminated or at least minimized. Thus the prodrug derivatives according to the invention degrade at least as rapidly to pilocarpine and the pro-moiety when compared to the prodrugs of Bundgaard et al. of corresponding lipophilicity , and they also promote at least to the same degree the penetration of pilocarpine through the cornea. In addition, the bispilo- carpate derivatives carry into the cornea one pro-moiety for every two pilocarpine molecules, whereas the deriva¬ tives of Bundgaard et al. carry one pro-moiety for every pilocarpine molecule. The diffusion coefficient of the bispilocarpate derivatives in the corneal epithelium is smaller than that of the Bundgaard compounds, wherefore still undegraded bispilocarpate derivatives remain in the corneal epithelium longer. Thus there will be more time left for the prodrug to break down completely. In addition, the novel compounds of the invention have a better solubi¬ lity, and are thus better suited for the preparation of drug formulations. Thus the invention allows for extended slow drug release from the cornea into the inner parts of the eye, by means of which it is possible to effectively prolong the dura¬ tion of action of pilocarpine and also reduce the peaks of high pilocarpine concentration in the eye, which is of importance from the view of reducing the afore mentioned side effects. The novel pilocarpine prodrug-derivatives of the inventi- on, specifically bispilocarpic acid esters, i.e. bispilo- carpates, have the general formula I wherein A) Y is -C(=0)-R, wherein R is C 1 ~C 4 -alkyl, C 3 -C 6 -cy- cloalkyl or phenyl, and W is the group I CH, wherein Y has the meaning given above, and A is a direct bond or a methylene group, which can be substituted with hydroxy, the group Y-O- wherein Y has the meaning given, or with one or two methyl groups, or B) W has the meaning of R' which is C j -C.-alkyl or C_-C 8 - cycloalkyl, and Y has the meaning of wherein B has the meaning of a direct bond, methylene or ethylene, and R' has the meaning given above, with the proviso that when both the R and R' groups in the compound (I) are ethyl, A and B are different from a direct bond and A in addition is different from OH-substituted methylene group, as well as the acid addition salts of the said compounds. A preferred subgroup of the compounds of the formula (I) is thus formed by the compounds having the formula (IA) wherein Y and A have the meanings indicated above, with the proviso that when both R groups are ethyl, A is different from a direct bond or OH-substituted methylene. In the formula (IA) R is preferably C 3 -C 8 -cycloalkyl or a straight or branched propyl or butyl, whereby A advantageously is a direct bond, unsubstituted methylene or methylene substituted with hydroxy or with one or two methyl groups, especially a direct bond or unsubstituted methylene. According to a further embodiment, A has the meaning of a unsubstituted methylene or methylene substituted with one or two methyl groups, and R has the meaning indicated, especially C 1 -C 4 ~alkyl or C 3 -C 6 -cycloalkyl. A second advantageous subgroup according to the invention is formed by compounds having the formula (IB) wherein R' and B have the meanings indicated, with the proviso that when both R' groups are ethyl, B is different from a direct bond. A first subgroup of compounds of the formula (IB) is formed by compounds, wherein B has the meaning of unsubstituted methylene or ethylene and R' has the meaning indicated in connection with formula (IB) , such as C 1 -C 4 -alkyl. In the formula (IB) R' can also be C 3 -C 6 -cycloalkyl or straight or branched propyl or butyl, whereby B advantageously has the meaning of a direct bond, or unsubstituted methylene or ethylene, especially a direct bond or unsubstituted methylene. In connection with the afore mentioned general formula I, C 1 -C 4 -alkyl is straight or branched, advantageously met¬ hyl, ethyl, propyl, butyl. It is preferably straight or branched propyl or butyl, such as n-, i-propyl, n-, i- or t-butyl. Cycloalkyl R or R' has 3-6 ring carbon atoms, which may also be substituted with a methyl group, such as cyclopro- pyl or cyclobutyl. In the compounds, preferably both the groups R and R' are equal. The acid addition salts of the compounds according to formula I are preferably pharmaceutically acceptable addition salts with non-toxic inorganic or organic acids. As examples of suitable acids hydrochloric, hydrobromic, sulphuric, nitric, phosphoric acid etc. , and as organic acids for example acetic, propionic, stearic, oxalic, malonic, succinic, glutaric, adipic, maleic, fumaric, malic, tartaric, citric, ascorbic, benzoic, pa oic or sulphonic acid, such as mesyl or tosyl acid, may be mentioned. Preferred individual compounds of the formula (IA) are: O,0'-dicyclopropylcarbonyl (1,2-ethylene) bispilocarpate O,0'-dicyclobutylcarbonyl (1,2-ethylene) bispilocarpate O,0'-dicyclopropylcarbonyl (1,3-propylene) bispilocarpate O,0'-dicyclobutylcarbonyl (1,3-propylene) bispilocarpate O,0 , -dicyclopropylcarbonyl (2-methyl-l,3-propylene) bispi- locarpate O,0 , -dicyclopropylcarbonyl (2,2-dimethyl-l,3-propylene) bispilocarpate O,0'-dipropionyl (1,3-propylene) bispilocarpate O,0'-dicyclopropylcarbonyl (2-hydroxy-l, 3-propylene) bispi¬ locarpate O,0'-dicyclopropylcarbonyl (2-cyclopropylcarbonyloxy-l, 3- propylene) bispilocarpate 0,0 , -dipivalyl (1,2-ethylene) bispilocarpate 0,0'-dipivalyl (1,3-propylene) bispilocarpate O,0'-di(l-methylcyclopropylcarbonyl) (1,2-ethylene) bispi¬ locarpate O,0'-dicyclopentylcarbonyl (1, 2-ethylene) bispilocarpate O,0'-diisobutyryl (1,2-ethylene) bispilocarpate O,0 -dicyclohexylcarbonyl (1,2-ethylene) bispilocarpate - O,0'-dicyclopentylcarbonyl (1, 3-propylene) bispilocarpate O,0 -dicyclohexylcarbonyl (1, 3-propylene) bispilocarpate O,0'-dibenzoyl (1, 2-ethylene) bispilocarpate O,0'-dibenzoyl (1,2-propylene) bispilocarpate. Preferred compounds of the formula (IB) are: 0,0i'-succinyl (diisopropyl) bispilocarpate 00,,00'-succinyl (di-t-butyl) bispilocarpate 0,0 >'-succinyl (dicyclopropyl) bispilocarpate 0,0 >'-succinyl (dicyclobutyl) bispilocarpate 0,0 >'-glutaryl (diisopropyl) bispilocarpate 0,0t'-glutaryl (di-t-butyl) bispilocarpate 00,,00'-glutaryl (dicyclopropyl) bispilocarpate 0,0 >'-glutaryl (dicyclobutyl) bispilocarpate. The invention relates also to a process for the prepa¬ ration of the compounds according to the formula I. According to the process of the invention, a) for the preparation of a compound having the formula wherein A and Y have the meanings indicated above in connection with the formula (I) , a compound having the formula wherein A has the same meaning as above, is reacted with an acid of the formula RC0 2 H, or a functional derivative thereof, wherein R has the meaning indicated above, or b) for the preparation of a compound of the formula wherein B and R' have the meanings given in in connection with the formula (I) , a compound of the formula wherein R' has the same meaning as above, is reacted with a dicarboxylic acid of the formula O O •» U HO-C-CH 2 -B-CH 2 -C-OH or a bifunctional acid derivative thereof, wherein B has the same meaning as above, and optionally the compound obtained is converted to its acid addition salt. For the preparation of the compound used above as starting material in the process a) , pilocarpic acid of the formula is reacted with a compound of the formula X-CH 2 -A-CH 2 -X' , wherein X and X', indepedently, have the meaning of hydroxy, or a leaving group, such as halogen, acyloxy, alkyl- or aryl sulfonyloxy, and A has the same meaning as above. For the preparation of the compound used above as starting material in the process b) , pilocarpic acid as defined above, is reacted with a compound of the formula R'X, wherein X has the meaning of hydroxy, or a leaving group, such as halogen, acyloxy, or alkyl- or aryl sulfonyloxy, and R' has the same meaning as above. In the above mentioned reactions, as the functional acid derivatives, preferably the halogenides, anhydrides, alkyl or aryl sulfonates thereof are used. As the reaction medium, solvents such as hydrocarbons, halogenated hydro¬ carbons, ethers, ketones etc. are used, which are inert to the reagents. Suitable hydrocarbons are the aromatic hydrocarbons, such as benzene and alkyl benzenes, such as toluene and xylene. Suitable halogenated hydrocarbons are for example dichloro ethane, chloroform and chlorobenzene. As ketones acetone, ethyl methyl ketone and isobutyl methyl ketone may be mentioned, and as ethers diethyl ether, di¬ isopropyl ether, dibutyl ether and 1,4-dioxane may be mentioned. Other suitable solvents include dimethyl sulfoxide, dimethylformamide and acetonitril. The reaction temperature is not critical but may vary for example from -10°C to the boiling point of the solvent. Suitably room temperature is used. The reaction time may vary within broad limits and is conventionally 12-72 hours, usually about 24 hours. It is advantageous to use acid binding agents in the reactions, such as alkali metal and alkaline earth metal carbonates or organic bases. Suitable metal carbonates include sodium carbonate and potassium carbonate and as organic bases pyridine and its homologues, 4-(dimethylamino)pyridine, quinoline and its homologues, N,N-dimethylaniline and trialkylamines, preferably triethylamine. The said reactions may take place either in a homogenous solution or in a heterogenic system, such as under PTC-conditions. The ester bonds of the compounds according to the inven¬ tion may be formed also by using known water cleaving reagents, such as carbodiimides. In some cases also the known acid catalyzed esterification reactions may come into question. The invention relates also to the pharmaceutical composi- tions containing the compound of the invention as the active agent together with pharmaceutically acceptable adjuvants and carriers. The pharmaceutical compositions according to the inventi- on are prepared in a known manner by using carriers and other adjuvants known in the art. The carriers may, for example, be liquids, suspensions or emulsions, or creams and ointments. The composition may also be formed into a solid pharmaceutical form to be inserted in the eye. A suitable form of administration is for example an eyedrop solution which contains the compound according to the invention at a suitable concentration, for example 0.1- 4 %, in a sterile aqueous solution buffered to a suitable pH or adjusted to a suitable pH with an acid or a base, the compound preferably being used in its water soluble acid addition salt form. An eyedrop solution with the said desired concentration is administered into the eye, depending on the condition of the patient, preferably 1 to 3 times a day. TEST METHODS The compounds of the invention have been tested in the following tests. 1) Lipophilicity The lipophilicity of the compounds was determined by measuring the partition coefficients (P) of the compounds at pH-values 7.40 and 5.00. The measurements were made in a 1-octanol-phosphate buffer mixture by determining the concentration of the compound to be studied in the buffer phase before and after partitioning. From the results it can be seen that all the compounds of the invention are more fat soluble than pilocarpine (log P = 0.01, pH 7.40 and -1.74, pH 5.0) , and the fat solubility of the derivatives can be regulated by changing the substituentε attached to pilocarpic acid. 2) Enzyme hydrolysis The half-lives of enzyme hydrolysis of the bispilocarpates according to the invention were determined in a plasma/buf¬ fer mixture and/or rabbit corneal homogenate. A. In a plasma/buffer mixture The half-lives of enzyme hydrolysis of bispilocarpic acid diesters were determined in a plasma/phosphate buffer pH 7.40 -mixture (80%-20%) ) at 37°C. The logarithm of re¬ maining diester was presented as a function of time and from the plot obtained was determined the half-life T j . From the results it may be seen that in buffer solutions the stable diester degrades under the influence of plasma esterases to O,0'-dihydrogen bispilocarpate and monopilocarpate intermediates, which are chemically degraded to active pilocarpine at physiological pH-value. The degradation rate of the prodrug derivative can be regulated by changing the subεtituents attached to pilocarpic acid. B. In corneal homogenate The half-lives of enz" a hydrolysis of bispilocarpic acid diesters were determ-wed in rabbit corneal homogenate pH 7.40 at 37°C. The corneal homogenate was prepared in 0.05 M Tris buffer. The logarithm of remaining diester was presented as a function of time and from the plot obtained the half-life T, was determined. From the results it can be seen that the esterases of rabbit eye cornea hydrolyze bispilocarpic acid diesters to a O,0'-dihydrogen bispilocarpate and monopilocarpate intermediates, which chemically degrade to active pilocarpine at physiological pH-value. The degradation rate of the prodrug derivative can be regulated by changing the substituents to be attached to pilocarpic acid. 3) Corneal penetration The corneal penetration of the novel bispilocarpates according to the invention was studied in a diffusion chamber, wherein the migration of the compound was follo¬ wed from the delivering phase (epithelium side) through the cornea to the acceptor side (endothelium side) of the diffusion chamber. In the study, rabbit eye cornea was used. The permeability coefficients (P aDD ) were calculated from the permeability rate. From the results it is seen that with the novel compounds it is possible to improve the corneal permeability of pilocarpine (P a __ = 2.77 cm/s x 10 ~6 ) . The results show that the compounds of the invention are hydrolyzed in the cornea forming pilocarpine and that with the groups attached to pilocarpic acid it is possible to regulate the corneal penetration of the prodrug and the rate of formation of pilocarpine. It is worth mentioning that the permeability coefficient is smaller for derivati¬ ves which release pilocarpine only at a slow rate, due to e.g. the appropriately slow chemical hydrolysis of the intermediate liberated from the derivative, than for derivatives, from which pilocarpine is released rapidly. Conclusion The fat solubility, enzymatic hydrolysis, corneal penet- ration and the chemical hydrolysis of the intermediate of the compounds according to the invention and thus the formation of active pilocarpine in the eye can be easily regulated according to purpose by changing the chemical groups attached to the pilocarpic acid. Bispilocarpic acid diesters are enzymatically hydrolyzed to bispilocarpic acid esters and pilocarpic acid monoesters respectively, which are chemically (spontaneously) hydrolyzed to pilocarpine. The bispilocarpic acid diesters according to the inventi- on transfer to the cornea one pro-moiety for every two pilocarpine molecules, whereby the amount of pro-moieties released is minimized. The minimization of the amount of released pro-moieties is aimed at reducing drug related irritation and smarting of the eye. As fat soluble compounds the bispilocarpic acid diesters of the invention are effectively absorbed into the corneal epithelium, where the corneal esterases rapidly release a suitable water soluble intermediate (e.g. O,0'-dihydrogen (1,2-ethylene) bispilocarpate (from IA) or O-hydrogen (ethyl) bispilocarpate, (from IB) , resp. , which as a water soluble compound is capable to migrate from the epithelium to the stroma and from there into the inner parts of the eye towards its action site releasing pilocarpine continuously during migration. Thus there is no excessive accumulation of prodrug-derivative nor pilocarpine in the corneal epithelium, which might cause irritation of the eye. By means of the compounds of the invention it is possible to eliminate to a large extent the disadvantages relating to drug treatment with pilocarpine (poor biological availability, system and eye side effects, frequent ad¬ ministration and thus poor patient compliance) . Due to the better corneal permeability, the compounds of the invention may be administered in considerably smaller doses and the number of doses/day may be reduced, whereby the side effects are reduced, patient compliance is improved and the drug treatment of the glaucoma patients is made more effective. The following examples illustrate the invention without limiting the same in any way. EQUIPMENT USED Melting point determination: Reichert Thermovar apparatus Determination of refraction index: Atago Illuminator apparatus pKa-value determination: titrating the derivative in a water-ethanol mixture (50%-50%) Mass spectrometer: VG 70-250SE Test conditions in the electron bomb ionisator: electron energy: 70 eV (unless otherwise mentioned) ionisation current: 500 μA ionisation chamber temperature: 150°C sample holder temperature 30°C => 500°C in 2-5 minutes resolution: 10.000 Thermospray-mass spectrometer: VG thermospray/plasmaspray VG Trio-2 quadropole Beckmann 112 pump Test conditions in the thermospray-ionisation optimized daily NMR-spectrometer: Bruker AC 250/Aspect 3000 1 H/ 13 C 5 mm dual probe CD 3 OD 20 mg/ml δ ppm (tetramethylsilane = O) Example 1 O,0 -Dihydrogen (1,2-ethylene) bispilocarpate (Y = hydrogen, A = direct bond) The monoester was prepared by adding 247 mg (1.31 mmoles) of 1,2-dibromoethane dropwise to a solution containing 1302 mg (5.25 mmoles) pilocarpic acid sodium salt in 60 ml of dimethyl sulfoxide. The solution was mixed at room temperature for 72 hours and poured into 100 ml of dis¬ tilled water. The mixture was extracted with two portions of each 100 ml of chloroform. The combined chloroform extracts were washed with 100 ml of distilled water, with 100 ml of 2 % sodium bicarbonate solution and with 100 ml of distilled water. The chloroform extracts were dried on calcium sulfate (30 min) and the chloroform evaporated under reduced pressure, and the bispilocarpate obtained was crystallized from a ethyl acetate/ether mixture, whereby 332 mg (0.69 mmoles) of the title compound were obtained. M.p. = 111-115°C pK a = 6.30 HR-MS-spectrum: m/e (relative intensity) : 209 (8%) , 208 (19%), 96 (30%), 95 (100%). NMR: δ 7.49 2H bs, 6.74 2H bs, 4.30 4H m, 3.60 6H s, 3.54 4H m, 2.73 2H m, 2.56 2H m, 2.51 2H m, 2.02 2H m, 1.68 4H m, 0.89 6H t. The starting material, the sodium salt of pilocarpic acid, can be prepared as follows: Pilocarpine hydrochloride (3.92 g; 16.00 mmoles) was dissolved in distilled water (4 ml) and the solution was cooled to about 0°C. To the solution 18 ml of ice cold 2M NaOH were added in four portions. The solution was left standing at about 0°C for one hour. After neutralizing excess NaOH with 5 ml of IM HC1, the solution was evapo- rated under reduced pressure. The residue was dissolved in 60 ml of absolute ethanol and mixed for 10 minutes at 60°C. After cooling to 4°C undissolved NaCl was removed by filtration. The filtrate was evaporated under reduced pressure, whereby 3.93 g of sodium pilocarpate were obtained as a white, extremely hygroscopic substance. Correspondingly, O,0'-dihydrogen (1,3-propylene) bispilo¬ carpate was prepared from the sodium salt of pilocarpic acid (1021 mg; 4.11 mmoles) and 1,3-dibromopropane (208 mg; 1.03 mmoles). The yield is 330 mg (0.70 mmoles). Correspondingly, O,0 -dihydrogen (2-hydroxy-1,3-propylene) bispilocarpate can be prepared from the sodium salt of pilocarpic acid (1674 mg; 6.75 mmoles) and 1,3-dibromo-2- hydroxy propane (341 mg; 1.69 mmoles). O,0'-dihydrogen (2-hydroxy-1, 3-propylene) bispilocarpate can also be prepared from the sodium salt of pilocarpic acid and epichlorohydrine (2:1) . Example 2 O,0'-Dicyclopropylcarbonyl (1,2-ethylene) bispilocarpate (Y = cyclopropylcarbonyl; A = direct bond) The compound was prepared by adding 945 mg (9.64 mmoles) of cyclopropylcarbonyl chloride dropwise during ca. 24 hours to a mixture containing O,0'-dihydrogen (1,2-ethyle¬ ne) bispilocarpate (540 mg; 1.13 mmoles) (see Example 1) and 1866 mg potassium carbonate (13.5 mmoles) in toluene (150 ml) . The mixture was stirred for 24-72 hours. To the reaction mixture a 2 % sodium bicarbonate solution (150 ml) was added and the mixture was stirred at room temperature for 3 hours. The layers were separated and the toluene phase washed twice with water (2 x 150 ml) , was dried on calcium sulfate (30 min) and evaporated under reduced pressure, whereby O,0'-dicyclopropylcarbonyl (1,2-ethyle- ne) bispilocarpate was obtained. The yield was 304 mg (0.49 mmoles) . pK a = 5.70 HR-MS-spectrum: m/e (relative intensity) : 614 [M + '] (1%) , 408 (11%), 393 (10%), 321 (7%), 320 (29%), 307 (9%), 291 (16%), 209 (18%), 208 (11%), 207 (78%), 163 (29%) , 162 (14%), 121 (47%), 113 (52%), 96 (38%), 95 (100%) . HR-MS: molecular weight = 614.3299260 (measured) 614.3315650 (calculated) . NMR: δ 7.56 2H bs, 6.78 2H bs, 4.35 4H , 4.08 4H m, 3.63 6H s, 2.69 4H m, 2.50 2H m, 2.33 2H m, 1.69 4H m, 1.61 2H , 1.10 6H t, 0,92 6H t, 0.90 8H m. Example 3 O,0'-Dicyclobutylcarbonyl (1,2-ethylene) bispilocarpate (Y = cyclobutylcarbonyl, A direct bond; fumarate) The compound was prepared from O,θ'-dihydrogen (1,2- ethylene) bispilocarpate (470 mg; 0.98 mmoles) (see Example 1) and cyclobutylcarbonyl chloride (931 mg; 7.86 mmoles) according to the method described in Example 2. The fumarate salt was made by dissolving the compound in toluene, adding fumaric acid in 2-propanol and precipitating with petroleum ether. The yield was 810 mg (0.82 mmoles) . M.p. = 49-51°C (fum.) HR-MS-spectrum: m/e (relative intensity) : 642 [M +* ] (4%) , 529 (6%), 436 (10%), 423 (22%), 422 (100%), 421 (13%) , 408 (18%) , 407 (85%) , 335 (10%), 221 (52%), 209 (12%) , 121 (13%), 96 (86%), 95 (50%). HR-MS: molecular weight = 642.3648680 (measured) 642.3628651 (calculated) NMR: δ 8.50 2H bs, 7.23 2H bs, 6.73 s (fu .) , 4.36 4H m, 4.11 4H m, 3.79 6H s, 3.16 2H m, 2.77 4H m, 2.54 2H m, 2.40 2H , 2.22 4H m, 2.01 4H m, 1.89 4H m, 1.71 4H m, 0.93 6H t. Example 4 O,0'-Dipropionyl (1,3-propylene) bispilocarpate (Y = propionyl, A = methylene) The compound was prepared from O,0'-dihydrogen (1,3- propylene) bispilocarpate (500 mg; 1.02 mmoles) (see Example 1) and propionyl chloride (751 mg; 8.12 mmoles) according to the method described in the Example 2. The yield was 467 mg (0.77 mmoles). pK fi = 5.95 HR-MS-spectrum: m/e (relative intensity) : 604 [M +# ] (6%) , 517 (7%), 411 (13%), 410 (57%), 396 (16%), 395 (71%), 339 (36%), 209 (15%), 208 (6%), 195 (48%), 121 (20%), 96 (56%) , 95 (100%) . HR-MS: molecular weight = 604.3491210 (measured) 604.3472151 (calculated). NMR: δ 7.56 2H bs, 6.76 2H bs, 4.18 4H m, 4.08 4H m, 3.62 6H s, 2.69 4H m, 2.49 2H m, 2.33 2H m, 2.31 4H q, 2.01 4H qv, 1.68 4H m, 1.10 6H t, 0.91 6H t. Example 5 O,0'-Dicyclopropylcarbonyl (1, 3-propylene) bispilocarpate (Y = cyclopropylcarbonyl, A = methylene) The compound was prepared from O,0'-dihydrogen (1,3- propylene) bispilocarpate (422 mg; 0.86 mmoles) (see Example 1) and cyclopropylcarbonyl chloride (719 mg; 6.88 mmoles) according to the method described in Example 2. The yield was 297 mg (0.47 mmoles) . pK = 6.05 HR-MS-spectrum: m/e (relative intensity) : 629 (4%) , 628 [M +- ] (7%) , 423 (19%) , 422 (76%), 408 (16%) , 407 (73%), 352 (10%), 351 (40%), 335 (9%) , 334 (9%) , 209 (19%), 208 (11%) , 207 (73%), 121 (32%), 96 (55%) , 95 (100%). HR-MS: molecular weight = 628.3428340 (measured) 628.3472151 (calculated). NMR: δ 7.51 2H bs, 6.73 2H bs, 4.19 4H m, 4.07 4H m, 3.61 6H s, 2.68 4H m, 2.49 2H m, 2.33 2H m, 2.02 2H qv, 1.68 4H , 0.91 6H t, 0.90 8H m. Example 6 O,0'-Dicyclobutylcarbonyl (1,3-propylene) bispilocarpate (Y = cyclobutylcarbonyl, A = methylene, fumarate) The compound was prepared from O,0'-dihydrogen (1,3- propylene) bispilocarpate (705 mg; 1.43 mmoles) (see Example 1) and cyclobutylcarbonyl chloride (1357 mg; 11.45 mmoles) according to the method described in Example 2. The fumarate salt was crystallized according to Example 3. The yield was 960 mg (0.96 mmoles). M.p. = 33-35°C (fum.) HR-MS-spectrum: m/e (relative intensity) : 657 (4%) , 656 [M +* ] (6%), 543 (9%) , 437 (23%), 436 (100%), 422 (22%) , 421 (86%), 366 (10%), 365 (46%), 222 (9%), 221 (58%), 209 (14%) , 121 (15%), 96 (68%), 95 (78%) . HR-MS: molecular weight = 656.3743290 (measured) 656.3785152 (calculated) . NMR: δ 8.50 2H bs, 7.23 2H bs, 6.73 s (fum.), 4.21 4H m, 3.80 6H s, 3.16 2H m, 2.78 4H m, 2.53 2H m, 2.40 2H m, 2.22 4H m, 2.03 2H qv, 2.01 4H m, 1.89 4H , 1.71 4H , 0.92 6H t. Example 7 0,0'-Dipivalyl (1,2-ethylene) bispilocarpate (Y = pivalyl, A = direct bond, fumarate) The compound was prepared from O,0'-dihydrogen (1,2- ethylene) bispilocarpate (384 mg; 0.80 mmoles; see Example 1) and pivalyl chloride (772 mg; 6.41 mmoles) according to the method disclosed in Example 2. The fumarate salt was crystallized according to Example 3 from a 2- propanol/toluene/petroleum ether mixture. Yield 293 mg (0.29 mmoles) . M.P. = 61 - 65 °C (fum.) HR-MS-spectrum: m/e (relative intensity) : 647 (5%) , 646 [M +# ] (7%), 645 (3%), 631 (6%), 531 (6%), 425 (24%), 424 (91%), 410 (17%), 409 (67%) , 337 (9%), 293 (7%), 223 (34%), 209 (9%), 163 (9%) , 123 (10%), 122 (5%), 121 (29%), 96 (84%) , 95 (100%) . HR-MS: molecular weight = 646.39318800 (measured) 646.39416531 (calculated). NMR: δ 8.51 2H bs, 7.23 2H bs, 6.73 s (fum.), 4.37 4H m, 4.10 4H m, 3.80 6H s, 2.78 4H m, 2.55 2H m, 2.39 2H m, 1.71 4H , 1.20 18H s, 0.93 6H t. Example 8 O,0'-Dicyclopentylcarbonyl (1, 3-propylene) bispilocarpate (Y = cyclopentylcarbonyl, A = methylene, fumarate) The compound was prepared from O,0'-dihydrogen (1,3- propylene) bispilocarpate (401 mg; 0.81 mmoles; see Example 1) and cyclopentylcarbonyl chloride (859 mg; 6.48 mmoles) according to the method disclosed in Example 2. The compound was crystallized from a 2- propanol /toluene/ petroleum ether mixture. Yield 501 mg (0.48 mmoles) . M.P. = The compound is hygroscopic HR-MS-spectrum: m/e (relative intensity) : 685 (4%) , 684 [M + '] (6%) , 683 (2%), 451 (11%), 450 (48%), 436 (7%) , 435 (25%) , 379 (15%), 235 (29%), 209 (12%), 163 (12%) , 121 (31%) , 96 (47%) , 95 (100%) . HR-MS: molecular weight = 684.4060820 (measured) 684.4098154 (calculated) . NMR: δ 8.57 2H bs, 7.27 2H bs, 6.72 s (fum.), 4.21 4H t, 4.10 4H d, 3.81 6H s, 2.80 4H m, 2.75 2H m, 2.54 2H m, 2.40 2H m, 2.03 2H qv, 1.88 4H m, 1.74 4H m, 1.71 4H m, 1.62 8H m, 0.92 6H t. Example 9 O,0'-Dicyclohexylcarbonyl (1, 3-propylene) bispilocarpate (Y = cyclohexylcarbonyl, A = methylene, fumarate) The compound was prepared from O,0'-dihydrogen (1,3- propylene) bispilocarpate (424 mg; 0.86 mmoles; see Example 1) and cyclohexylcarbonyl chloride (1009 mg; 6.88 mmoles) according to the method disclosed in Example 2. The compound was crystallized from a 2- propanol /toluene/ petroleum ether mixture. Yield 722 mg (0.68 mmoles) . M.P. = 50 - 53 °C HR-MS-spectrum: m/e (relative intensity) : 713 (2%) , 712 [M +* ] (6%), 711 (3%) , 465 (16%), 464 (54%), 450 (9%), 449 (31%), 394 (5%), 393 (18%), 250 (6%) , 249 (33%) , 209 (12%) , 163 (12%) , 121 (32%) , 96 (56%), 95 (100%). HR-MS: molecular weight = 712.4428410 (measured) 712.4411156 (calculated) . NMR: δ 8.55 2H bs, 7.26 2H bs, 6.71 s (fum.) , 4.20 4H t, 4.09 4H d, 3.81 6H s, 2.79 4H , 2.54 2H m, 2.39 2H m, 2.32 2H m, 2.03 2H qv, 1.87 4H m, 1.74 4H m, 1.72 4H m, 1.70 4H , 1.38 8H m, 0.92 6H t. Example 10 0,0'-Glutaryl (diethyl) bispilocarpate (R' = ethyl, B = methylene) 9.80 mmoles of ethylbromide (1068 mg) were added dropwise within about an hour to a solution containing 9.80 mmoles (2432 mg) of pilocarpic acid sodium salt in 60 ml of di¬ methyl sulfoxide. The solution was stirred at room te pe- rature for 48-72 hours and poured into 100 ml of distilled water. The mixture was extracted with two portions of each 150 ml of ethyl acetate. The combined ethyl acetate ext¬ racts were washed with 150 ml of distilled water, with 150 ml of 2 % sodium bicarbonate solution and with 150 ml of distilled water. The ethyl acetate extracts were dried on calcium sulfate (30 min) and the ethyl acetate evaporated under reduced pressure, and the pilocarpic acid ethyl ester obtained was crystallized from a chloroform/petroleum ether mixture, whereby 448 mg (1.76 mmoles) of the ester were obtained. M.p. = 104-107°C pK a = 6.60 HR-MS-spectrum: m/e (relative intensity) : 254 [M + ] (17%) , 236 (18%), 223 (11%), 209 (24%) , 207 (11%) , 163 (14%), 139 (46%) , 121 (31%) , 96 (53%) , 95 (100%) . HR-MS: molecular weight = 254.1620180 (measured) 254.1630428 (calculated) NMR: «S 7.49 1H bs, 6.74 1H bs, 4.13 2H m, 3.61 3H s, 3.55 2H m, 2.73 1H m, 2.53 1H m, 2.50 1H m, 2.03 2H m, 1.68 2H m, 1.27 3H t, 0.90 3H t. The starting material, the sodium salt of pilocarpic acid, may be prepared according to Example 1. Glutaryl chloride (157 mg; 0.93 mmoles) was added dropwise within about 24 hours to a mixture containing 589 mg of pilocarpic acid ethyl ester and 1282 mg (9.27 mmoles) cal¬ cium carbonate in toluene (65 ml) . The solution was stir¬ red at room temperature for ca. 48 hours. To the reaction mixture 2 % sodium bicarbonate solution (60 ml) was added and the mixture was stirred at room temperature for 3 hours. The layers were separated and the toluene phase washed twice with distilled water (2 x 100) , was dried on calcium sulfate (30 min) and evaporated under reduced pressure, whereby 0,0'-glutaryl (diethyl) bispilocarpate (152 mg; 0.25 mmoles) was obtained. HR-MS-spectrum: m/e (relative intensity) : 604 [M + ] (7%) , 559 (11%), 490 (21%), 489 (75%), 237 (9%), 223 (6%), 209 (8%), 163 (10%), 123 (6%), 122 (10%), 121 (100%), 96 (26%), 95 (61%). HR-MS: molecular weight = 604.3478240 (measured) 604.3472151 (calculated) NMR: δ 7.53 2H bs, 6.74 2H bs, 4.13 4H m, 4.08 4H m, 3.61 6H s, 2.67 4H m, 2.45 2H m, 2.39 4H m, 2.30 2H m, 1.89 2H m, 1.67 4H m, 1.26 6H t, 0.90 6H t Example 11 O,0'-Adipoyl (diethyl) bispilocarpate (R' = ethyl, B = ethylene) The compound was prepared from the ethyl ester of pilocarpine (609 mg; 2.40 mmoles) and adipoyl chloride (176 mg; 0.96 mmoles) according to Example 10. Yield 259 mg (0.42 mmoles) . HR-MS-spectrum: m/e (relative intensity) : 618 [M + J (10%) , 573 (9%), 504 (20%), 503 (67%), 489 (10%), 368 (10%), 365 (17%) , 295 (9%), 249 (29%), 237 (11%), 236 (24%) , 223 (15%) , 209 (18%) , 207 (20%), 163 (21%), 123 (9%) , 122 (12%), 121 (100%), 96 (51%). HR-MS: molecular weight = 618.3625030 (measured) 618.3628652 (calculated) NMR: δ 7.53 2H bs, 6.73 2H bs, 4.13 4H m, 4.08 4H m, 3.61 6H s, 2.67 4H m, 2.47 2H m, 2.34 4H m, 2.30 2H m, 1.68 4H m, 1.63 4H m, 1.26 6H t, 0.90 6H t

Claims: Claims 1. Bispilocarpic acid ester derivatives of the general formula wherein A) Y is -C(=0)-R, wherein R is C 1 ~C 4 -alkyl, C 3 -C 6 -cy- cloalkyl or phenyl, and is the group i CH, wherein Y has the meaning given above, and A is a direct bond or a methylene group, which can be substituted with hydroxy, the group Y-O- wherein Y has the meaning given, or with one or two methyl groups, or B) has the meaning of R' which is C 1 -C 4 ~alkyl or C 3 -C 6 ~ cycloalkyl, and Y has the meaning of • ^ = 0 / en, wherein B has the meaning of a direct bond, methylene or ethylene, and R' has the meaning given above, with the proviso that when both the R and R' groups in the compound (I) are ethyl, A and B are different from a direct bond and A in addition is different from OH- substituted methylene group, as well as the acid addition salts of the said compounds. 2. Bispilocarpic acid ester derivatives according to formula (I) of claim 1(A), wherein R is C 3 -C 6 -cycloalkyl. 3. Bispilocarpic acid ester derivatives according to formula (I) of claim 1(A), wherein R is straight or bran¬ ched propyl or butyl. 4. Bispilocarpic acid ester derivatives according to formula (I) of claim 1(A), wherein R is C 3 -C 6 -cycloalkyl or straight or branched propyl or butyl, and A has the meaning of a direct bond, unsubstituted methylene or methylene substituted with hydroxy, -0-Y or with one or two methyl groups, especially a direct bond or unsubstituted methylene. 5. Bispilocarpic acid ester derivatives according to formula (I) of claim 1(A), wherein R has the meaning indicated in claim 1(A) , especially C 1 -C 4 ~alkyl or C 3 -C 8 - cycloalkyl, and A has the meaning of a unsubstituted methylene or methylene substituted with one or two methyl groups. 6. Bispilocarpic acid ester derivatives according to formula (I) of claim 1(B), wherein B has the meaning of unsubstituted methylene or ethylene. 7. Bispilocarpic acid ester derivatives according to claim 6, wherein R' has the meaning of C 1 -C 4 ~alkyl. 8. Bispilocarpic acid ester derivatives according to formula (I) of claim 1(B), wherein R' is C 3 -C 6 -cycloalkyl or straight or branched propyl or butyl. 9. Bispilocarpic acid ester derivatives according to claim 8, wherein B has the meaning of a direct bond, unsubstituted methylene or ethylene, especially a direct bond or unsubstituted methylene. 10. Bispilocarpic acid ester derivative according to claim 1(A) which is O,0'-dicyclopropylcarbonyl (1,2-ethylene) bispilocarpate O,0'-dicyclobutylcarbonyl (1,2-ethylene) bispilocarpate O,0 , -dicyclopropylcarbonyl (1,3-propylene) bispilocarpate O,0'-dicyclobutylcarbonyl (1,3-propylene) bispilocarpate O,0'-dicyclopropylcarbonyl (2-methy1-1,3-propylene) bispi¬ locarpate O,0 -dicyclopropylcarbonyl (2,2-dimethyl-l,3-propylene) bispilocarpate O,0'-dipropionyl (1,3-propylene) bispilocarpate O,0'-dicyclopropylcarbonyl (2-hydroxy-1,3-propylene) bispi¬ locarpate O,0 -dicyclopropylcarbonyl (2-cyclopropylcarbonyloxy-l,3- propylene) bispilocarpate 0,0'-dipivalyl (1,2-ethylene) bispilocarpate 0,0'-dipivalyl (1,3-propylene) bispilocarpate 0,0'-di(1-methylcyclopropylcarbonyl) (1,2-ethylene) bispi- locarpate O,0 , -dicyclopentylcarbonyl (1,2-ethylene) bispilocarpate 0,0'-diisobutyryl (1,2-ethylene) bispilocarpate O,0'-dicyclohexylcarbonyl (1,2-ethylene) bispilocarpate O,0'-dicyclopentylcarbonyl (1,3-propylene) bispilocarpate O,0'-dicyclohexylcarbonyl (1,3-propylene) bispilocarpate O,0'-dibenzoyl (1,2-ethylene) bispilocarpate O,0'-dibenzoyl (1,2-propylene) bispilocarpate. 11. Bispilocarpic acid ester derivative according to claim IB, which is 0,0'-succinyl (diisopropyl) bispilocarpate 0,0'-succinyl (di-t-butyl) bispilocarpate 0,0'-succinyl (dicyclopropyl) bispilocarpate 0,0'-succinyl (dicyclobutyl) bispilocarpate 0,0'-glutaryl (diisopropyl) bispilocarpate 0,0 / -glutaryl (di-t-butyl) bispilocarpate 0,0'-glutaryl (dicyclopropyl) bispilocarpate 0,0 -glutaryl (dicyclobutyl) bispilocarpate. 12. Process for the preparation of a compound according to any one of the previous claims, characterized in that for the preparation of a compound according to claim IA having the formula wherein A and Y have the meanings indicated in claim IA, a compound havinq the formula wherein A has the same meaning as in the claim 1, is reacted with an acid of the formula RC0 2 H, or a functional derivative thereof, wherein R has the same meaning as in the claim IA, or b) for the preparation of a compound according to claim IB of the formula wherein B and R' have the meanings given in claim IB, a compound of the formula wherein R' has the same meaning as in the claim IB, is reacted with a dicarboxylic acid of the formula O O <ι 'I HO-C-CH 2 -B-CH 2 -C-OH or a bifunctional acid derivative thereof, wherein B has the same meaning as in the claim IB, and optionally the compound obtained is converted to its acid addition salt. 13. Pharmaceutical preparation, which contains as an active agent a compound according to any one of the claims 1 to 11 together with a pharmaceutically acceptable vehicle.

Inventors: HANHIJAERVI HANNU, JAERVINEN TOMI, PEURA PEKKA, POHJALA ESKO, SUHONEN PEKKA, URTTI ARTO, HANHIJAERVI, HANNU, JAERVINEN, TOMI, PEURA, PEKKA, POHJALA, ESKO, SUHONEN, PEKKA, URTTI, ARTO
Applicants: HANHIJAERVI HANNU, JAERVINEN TOMI, LEIRAS OY, PEURA PEKKA, POHJALA ESKO, SUHONEN PEKKA, URTTI ARTO
Application year: 1993
Main classification: C07D233
IPC codes: A61K31, A61P27, C07D233