WO1997023484A1

WO1997023484A1 - New compounds

Info

Publication number: WO1997023484A1
Application number: PCT/SE1996/001679
Authority: WO
Inventors: Fredrik Andersson; Tiiu Hansson; Lian Zhang
Original assignee: Astra Aktiebolag
Priority date: 1995-12-22
Filing date: 1996-12-17
Publication date: 1997-07-03
Also published as: SE9504618D0; AU1217797A

Abstract

The invention relates to novel tetrahydroisoquinolinyl carbamates of pyrroloindole derivatives of formula (I) having pharmacological actions and to processes for the synthesis of, and formulations containing such derivatives. It also relates to compounds which are intermediate products in the manufacture of said derivatives. These compounds which inhibit cholinesterase and are useful for enhancing memory and for treating Alzheimer's disease.

Description

NEW COMPOUNDS

Field of the invention

The present invention relates to novel tetrahydroisoquinolinyl carbamates of pyrroloindole derivatives having pharmacological actions and to processes for the synthesis of, and formulations containing such derivatives. It also relates to compounds which are intermediate products in the manufacture of said derivatives. More particularly, the present invention relates to compounds which inhibit cholinesterase and are useful for enhancing memory and for treating Alzheimer's disease.

Background of the invention

Acetylcholinesterase (AChE), sometimes called true or specific cholinesterase, is found in nerve cells, skeletal muscle, smooth muscle, various glands and red blood cells of mammals. AChE may be distinguished from other cholinesterases by substrate and inhibitor specificities and by distribution in the mammalian body. Its distribution in brain roughly correlates with cholinergic innervation and subfractionation shows the highest level in nerve terminals. AChE is also found in other animals, for example in the skin of the electric eel. Electric eel AChE has been used in pharmacology as a test model for human AChE.

It is generally accepted that the physiological role of AChE is the rapid hydrolysis and inactivation of acetylcholine. Inhibitors of AChE show marked chohnornimetic effects in cholinergically-innervated effector organs and have been used therapeutically in the treatment of glaucoma, myasthenia gravis and paralytic ileus. However, studies have suggested that AChE inhibitors may also be useful for alleviating memory dysfunctions characterized by a cholinergic deficit, such as Alzheimer's disease. Physostigmine is a potent acetylcholinesterase inhibitor. However, its therapeutic utility is limited by poor stability and low oral bioavailability, short duration of action and high acute toxicity. WO90/03552 and US 5,187,165 have disclosed (3a5-cw)-l,2,3,3a,8,8a-hexahydro- 1 ,3a,8-trimethylpyrrolo[2,3-Z?]indol-5-yl 3,4-dihydro-2( l )-isoquinolinecarboxylate (hereinafter referred to as C I) as having improved properties with respect to stability and duration of action in in vitro and in vivo tests. Oral bioavailability was also improved over physostigmine in in vivo tests with rats.

Because of the high toxicity of physostigmine it is desirable to find ways of reducing such effects while still retaining the high pharmacological potency of the selected compounds. Compounds having such beneficial properties could then be formulated as drugs for enhancing acetylcholine levels in the brain. Important properties for the utility of such drugs are high degree of inhibition of AChE, good stability, long duration of action , good bioavailability, good partition across the blood brain barrier, and few side effects.

Description of the invention

The present invention provides novel compounds which are acetylcholinesterase inhibitors and which have advantageous properties with respect to stability, duration of action, oral bioavailability and/or partition across the blood brain barrier. The compounds are easily metabolized and/or excreted from in the mammalian body. The compounds are indicated for use in alleviating states of cholinergic deficit leading to memory dysfunction e.g.

Alzheimer's disease. The compounds are also indicated for use in the treatment of other diseases resulting from cholinergic deficit e.g. glaucoma, myasthenia gravis and paralytic ileus.

The present invention relates to the 3aS- cis and 3aR- cis isomers or racemic mixtures or any other mixtures thereof of the compounds of formula I,

wherein R- and R₂ , which may be the same or different, are each H or CH₃, and R₃ is H or OH,

R4 and R5 , which may be the same or different, are each H, OH or OCH3,

provided that

a) at least one of Ri and R₂ is H when R₃ , Rj and R5 all are H,

b) when Ri and R₂ are both CH₃ and R₃ is OH, then ^ and R5 are both H,

c) when Ri and R₂ are both CH₃ and R₃ and R4 are both H, then R5 is OH in position 5 of the isoquinolyl moiety of the molecule,

d) when Rj and R2 are both CH3 , and R3 is H, then R4 and R5 are either both OH or both

OCH3 in positions 6 and 7 of the isoquinloyl moiety of the molecule,

and pharmaceutically acceptable acid addition salts thereof.

The compounds of the present invention have chiral centres and can, therefore, exist as enantiomeric forms and as racemates. Most preferred are the 3aS-cis compounds . These forms and racemates are included in the scope of the invention.

The compounds of the present invention can be used in the form of the free base or as pharmaceutically acceptable acid addition salts. Acceptable acids for this purpose include, but are not limited to, inorganic acids e.g. hydrochloric, hydrobromic, sulfuric, nitric, phosphoric and perchloric acids as well as organic acids e.g. tartaric, citric, acetic, succinic, maleic, fumaric and oxalic acids.

As examples of pharmaceutical compositions containing the compounds of the present invention the following can be mentioned: The compounds of the present invention may be orally administered, for example, with an inert diluent or with an edible carrier, or they may be enclosed in gelatin capsules, or they may be compressed into tablets. For the purpose of oral therapeutic administration, the active compounds of the invention may be incorporated with capsules, elixirs, suspensions, syrups, wafers, chewing gum and the like. The content of active substance of the preparations may be varied depending upon the particular form and may be between 0.5% to about 99% by weight of the dosage unit The amount of active compound in such compositions is such that a suitable unit dosage will be obtained. Preferred compositions and preparations according to the present invention are prepared so that an oral dosage unit form contains between 0.5 mg and 5000 mg of the active compound.

Because the compounds are rapidly eliminated they can suitably be injected into the mammalian body. For the purpose of parenteral therapeutic administration, the active compounds of the invention may be incorporated into a solution or suspension. These preparations should contain between 0.5% and 30% by weight of active compound. The amount of active compound in such compositions is such that a suitable dosage will be obtained. Preferred compositions and preparations according to the present invention are prepared so that a parenteral dosage unit contains between 0.5 mg and 100 mg of active compound.

The amount of active compound to be administered will vary depending on the severity of the disease and the mode of administration, but may be in the interval of 0.5 to 5000 mg active compound per day. The AChE inhibiting activity of the compounds of the present invention was demonstrated in the following two experiments.

The compounds of the present invention can be synthesised according to the following examples:

Example 1

(3a5-cw)-l,2,3,3a,8,8a-hexahydro-l,3a-dimethylpyrrolo[2,3-b]indol-5-yl 3,4-dihydro- 2(l )-isoquinolinecarboxylate (C II). The compound CH is synthesized by demethylation of C I via oxidation to (3a5-cw)-8- formyl-l,2,3,3a,8,8a-hexahydro-l,3a-dimethylpyrrolo [2,3-b] indol-5-yl 3,4-dihydro-2(l )- isoquinolinecarboxylate (C IX) and hydrolysis with a strong acid acid in aqueous solution according to the following: A mixture of C I (0.26 mmol), pyridinium dichromate (0.32 mmol), acetic anhydride (0.80 mmol) and CH₂Q₂ (3 ml) was heated under reflux for 1.5 h. The reaction mixture was filtered through a short silica gel column with a plug of ethyl acetate above it. The residue obtained after concentration of the solvent , was purified on a silica gel column

(CH₂α₂:CH₃OH , 50:1) giving C VI (64 mg, 164 μmol, 63%) as a clear syrup.

C IX (127 μmol) was hydrolyzed with 10% HCl (2ml) at room temperature. The solution was made basic with sat. NaHCO₃ and extracted with CH₂Q₂. The organic phase was washed with brine, dried Na₂SO and concentrated. The residue was purified on a silica gel column (CH₂α₂:CH₃OH, 10:1) giving C II (33 mg, 90 μmol, 71%).

¹³C-NMR (CDCI₃) δ 154.8, 146.8, 144.5, 137.7, 134.7, 133.5, 133.1, 129.0, 128.7, 126.7, 126.5, 126.4, 120.9, 116.9, 109.4, 90.1, 54.0, 52.5, 46.3, 46.1, 42.3, 41.7, 40.7, 36.7, 29.2, 28.9, 26.9 ^lH NMR (CDCI3) δ 7.26-7.14 (m, 4H), 6.63 (d, J = 2.3 Hz, IH), 6.77 (dd, J = 8.3, 2.3 Hz, IH), 6.55 (d, J = 8.3 Hz, IH), 4.81 (bs, IH), 4,69 (bs, IH), 4.51 (s, IH), 3.82 (m, 2H), 2.93 (bs, 2H), 2.78 (m, IH), 2.63 (m, IH), 2.47 (s, 3H), 2.02 (m, 2H), 1.45 (s, 3H) MS 363 (100, M⁺), 348 (5, M⁺-CH₃), 319 (25), 305 (7), 203 (25), 160 (24)

Example 2

(3a5-cw)-l,2,3,3a,8,8a-hexahydro-3a,8-dimethylpyrrolo[2,3-fr]indol-5-yl 3,4-dihydro- 2(lH)-isoquinolinecarboxylate (C HI).

This synthesis is suitable for the compounds of the present invention having a hydrogen in position 1 of the pyrroloindole moiety of the molecule. The compound is synthesized starting from (-J-N'-benzyleseroline according to Yu, Q.-S., Atack, J.R., Rapoport, I., Brossi, A.J., J. Med. Chem. 1988, 31, 2297-2300 to give (3aS- )-l,2,3,3a,8,8a- hexahydro- 1 -benzyl-3a,8-dimethylpyrrolo[2,3-b]indol-5-yl 3,4-dihydro- 2(lH)isoquinolinecarboxylate (C VII), which is then hydrogenated by treatment with hydrogen in the presence of a palladium catalyst , resulting in C HI.

The synthesis was performed as follows: To a solution of (-)-N¹-benzyleseroline (0.28 mmol) in CH₂Q₂ (1.8 ml) was added l '-carbonyldiimidazole (0.34 mmol). The mixture was stirred at room temperature for 1 h forming (3aS-cw)-l,2,3,3a,8,8a-hexahydro-3a,8- dimethylpyrrolo[2,3-fc]indol-5-yl imidazolecarboxylate after which 1,2,3,4- tetrahydroisoquinoline (0,62 mmol) was added. After 15 h the reaction mixture was concentrated to give a dark red residue , which was purified on a silica gel column (toluene:C2H₅OAc, 2: 1 ) to give C VII (100 mg, 0,22 mmol, 79%).

C VII (103 μmol) was dissolved in a mixture of CH OH:C2H₅OAc (10:1, 4 ml), and palladium hydroxide on carbon (4 mg) was added. After the mixture was stirred for 1 h under hydrogen at room temperature, the palladium catalyst was filtered through Celite (Fuller's Earth) and the solvent was evaporated in vacuo. The residue was purified on a silica gel column (CH₂α₂:CH3θH, 10: 1), giving C IH (29 mg, 80 μmol, 77%) as a white foam.

¹³C-NMR (CDCI₃) δ 154.7, 148.3, 142.8, 136.2, 134.5, 134.3, 133.3, 132.9, 128.8, 128.5, 126.5, 126.3, 126.1, 120.5, 116.5, 105.0, 92.6, 60.3, 52.1, 46.0, 45.9, 42.2, 42.1, 41.5, 32.4, 29.0, 28.7, 26.0 MS 363 (43, M*), 203 (100), 160 (36)

Example 3

(3aS-cw)-l,2,3,3a,8,8a-hexahydro-l,3a,8-ϋ τιethylpyκolo[2,3-fe]indol-5-yl 3,4-dihydro-4- hydroxy-2(lH)-isoquinolinecarboxylate (C IV).

This synthesis is suitable for compounds of the invention having a hydroxyl group in position 1, 3 or 4 of the isoquinoline moiety. The compounds are synthesized from eseroline and the corresponding 1,2,3,4-tetrahydro-hydroxyisoquinoline. Eseroline was synthesized as described by Yu, Q.-S., Schonenberger, B., Grossi, A., Heterocycles 1987, 26, 1271-1275. l,2,3,4-tetτahydro-4-hydroxyisoquinoline was synthesized as described by Ra„ S., Saxena, A.K., Jain, P.C., Ind. J. Chem. 1978, 16B, 1019.

To a solution of eseroline (787 μmol) in CH₂C1₂ (4 ml) was added l.T-carbonyldiimidazole (944 μmol). The mixture was stirred at room temperature for 1 h forming (3aS-cis)- 1 ,2,3,3a,8,8a-hexahydro- 1 ,3a,8-trimethylpyrrolo[2,3-&]indol-5-yl imidazolecarboxylate after which l,2,3,4-tetrahydro-4-hydroxyisoquinoline (1102 μmol) in CH₂C1₂ (1 ml) was added. After 15 h the reaction mixture was concentrated to give a residue, which was purified by column chromatography (CH₂Cl₂:CH3OH, 10:1) giving C IV (78 mg, 197 μmol, 25%) as a white foam. ¹³C-NMR (CDCI₃) δ 155.4, 149.6, 143.4, 137.5, 136.6, 136.5, 133.0, 132.7, 128.3, 128.1, 127.2, 127.0, 126.8, 126.1, 126.0, 120.6, 116.3, 106.7, 97.9, 66.1, 65.9, 53.2, 52.7, 48.9, 48.4, 46.2, 45.9, 40.7, 38.3, 37.1, 27.3

^XH NMR (CDCI₃) δ 7.48-7.15 (m, 4H), 6.82 (dd, J = 8.4, 2.4 Hz, IH), 6.77 (d, J = 2.4 Hz, IH), 6.34 (d, J = 8.4 Hz, IH), 5.05-4.50 (bm, 3H), 4.12 (s, IH), 3.96 (m, IH), 3.76 (bd, IH), 2.92 (s, 3H), 2.64 (m, IH), 2.61 (m, IH), 2.53 (s, 3H), 1,94 (m, 2H), 1,42 (s, 3H)

Example 4

(3a5-cw)-l,2,3,3a,8,8a-hexahydro-l,3a,8-trimethylpyKolo[2,3-b]mdol-5-yl 3,4-dihydro-5- hydroxy-2(lH)-isoquinolinecarboxylate (C V).

This synthesis is suitable for compounds having a hydroxyl substituent in any of positions 5, 6, 7 or 8 of the isoquinolinyl moiety of the compound. The compounds are synthesized via the corresponding methoxylated compound i.e. a compound having a methoxyl substituent in any of positions 5, 6, 7 or 8 by coupling the methoxy- 1,2,3,4- tetrahydromethoxyisoquinoline with eseroline and then demethylation of the intermediate compounds with a mineral acid, or a Lewis acid, e.g. BBr₃. Synthesis of the intermediate compound (3aS-cw)-l,2,3,3a,8,8a-hexahydro-l,3a,8- trimethylpyjTolo[2,3-ft]indol-5-yl 3,4-dihydro-5-methoxy-2(l )-isoquinolinecarboxylate (C

VIII).

To a solution of eseroline prepared from eseroline fumarate (1.176 g, 3 mmol) in CH₂Q₂ (15 ml) is added 1, -carbonyldiimidazole (0.729 g, 4.5 mmol). The solution is stirred at room temperature for two hours forming (3aS-cw)-l,2,3,3a,8,8a-hexahydro-l,3a,8- trimethylpyrrolo[2,3-&]indol-5-yl imidazolecarboxylate. 1 ,2,3,4-tetrahydro-5- methoxyisoquinoline (0.733 g, 4.5 mmol) is added and the solution is stirred at room temperature for 16 hours. CH₂C1₂ (50 ml) is added. The solution is washed with water, then with brine, dried over Na₂CO₃ and evaporated to give an oil. After flash chromatography on silica gel, eluted with a mixed solvent of C2H5OAC and methanol, 0.61 g of C Vffl is obtained (50% yield).

'H-NMR (CDC1₃, 300 MHz) 7.18 (IH, brt, J=8.1), 6.81 (IH, dd, Jι=2.3, J₂=8.3), 6.77 (2H, m), 6.73 (IH, m), 6.35 (IH, d, 5=8.3), 4.79 (IH, brs), 4.68 (IH, brs), 4.11 (IH, s), 3.84 (3H, s), 3.81 (IH, m), 3.77 (IH, m), 2.92 (3H, s), 2.84 (2H, m), 2.70 (IH, m), 2.65 (IH, m), 2.54 (3H, s), 2.05 (2H, m), 1.42 (3H, s).

Selected ¹³C-NMR

149.58, 143.29, 137.47, 126.81, 120.52, 116.23, 107.65, 116.23, 107.65, 106.59, 98.02, 55.33, 53.17, 52.59, 45.96, 60.85, 38.33, 37.12, 27.30. MS (m/e, %): 408 (m⁺+ 1, 14), 407 (m⁺, 57), 363 (15), 349 (4), 218 (14), 217 (100), 190 (34), 175 (6), 160 (55), 147 (6), 132 (21), 117 (7), 104 (5), 91 (9).

To a solution of HCl salt of C Vϋl (0.44 g, 1 mmol) in CH₂C1₂ (10 ml) BBr₃ is added at

0°C. The solution is stirrred at room temperature for 16 hours. 1 g of Na₂CO₃ and CH3OH (5ml) are added to the mixture at 0-5°C. After 2 hours the solvent is evaporated. CH₂Q₂ (60 ml) and water (20 ml) are added to the residue. The CH₂Q₂ layer is collected and the water layer is extracted with CH₂C1₂. The combined organic phase is washed with brine, dried over Na₂CO₃. After evaporation of solvent, 0.32 g of product is obtained (81% yield).

'H-NMR (CDCI₃, 300 MHz) 7.03 (IH, br.m), 6.82 (IH, dd, J-=2.4, J₂=8.3), 6.77 (IH, d, J=2.4), 6.67 (IH, d, J=8.7), 6.56 (IH, br.d, J=8.0), 6.35 (IH, d, J=8.3), 4.78 (IH, brs), 4.67 (IH, brs), 4.15 (IH, s), 3.85 (IH, m), 3.78 (IH, m), 2.92 (3H, s), 2.83 (2H, m), 2.73 (IH, m), 2.63 (IH, m), 2.54 (3H, s), 1.95 (2H, dd, J,=5.2, J₂=7.4), 1.42 (3H, s).

Selected ¹³C-NMR (CDC1₃, 75 MHz):

154.84, 154.11, 149.55, 143.36, 137.38, 134.36, 126.76, 120.60, 117.95, 116.75, 112.68, 106.71, 97.70, 77.19, 53.05, 52.68, 46.03, 41.89, 40.65, 38.03, 37.29, 27.24, 22.87.

Example 5

(3a5-cw)-l,2,3,3a,8,8a-hexahydro-l,3a,8-trimethylpyrrolo[2,3-b]indol-5-yl 3,4-dihydro-6,7-dimethoxy-2(l /)-isoquinolinecarboxylate (C VI).

To a solution of eseroline (0.75 mmol) in CH₂C1₂ (0.8 ml) was added 1,1'- carbonyldiimidazole (0.91 mmol). The mixture was stirred at room temperature for 45 min forming (3aS-cis)- 1 ,2,3,3a,8,8a-hexahydro- 1 ,3a,8-trimethylpyrrolo[2,3-b]indol-5-yl imidazolecarboxylate after which 6,7-dimethoxy-l,2,3,4-tetrahyα^oisoquinoline (1.10 mmol) in CH₂C1₂ (1 ml) was added. After 15 hours the reaction mixture was concentrated to give a residue, which was purified by column chromatography

(C₂H₅OAc:CH3OH:(C2H5)3N,4: 1:0.05) giving (3aS-cύ)-l,2,3,3a,8,8a-hexahydro-l,3a,8- trimethylpyrrolo[2,3-i»]indol-5-yl

3,4-dihydro-6,7-dimethoxy-2(lH)-isoquinolinecarboxylate (C VI)(254 mg, 0.58 mmol, 77%) as a white foam.

Example 6

(3aS-cw)- 1 ,2,3,3a,8,8a-hexahydro- 1 ,3a,8-trimethylpyrrolo[2,3-b]indol-5-yl

3,4-dihydro-6,7-dihydroxy-2(lH)-isoquinolinecarboxylate (C VII). The hydrochloride salt of (3&S-cis)- 1,2,3, 3a,8, 8a-hexahydro-l, 3a,8-trimethylpyrrolo[2,3- b]indol-5-yl

3,4-dihydro-6,7-dimethoxy-2(lH)-isoquinolinecarboxylate (C VI) (0.58 mmol) was suspended in CΗ₂C1₂ (2 ml) and cooled to 0° C. Boron tribromide (727 mg, 2.90 mmol) was added dropwise and stirred for 30 min at 0° C and then 20 hours at room temperature.

The mixture was cooled and triethylamine (0.5 ml) and methanol (0.5 ml) was added and stirred for 30 min at 10° C, concentrated and the residue was extracted between

CH₂Q₂:NaHCO₃, the organic phase was washed with NaCl(aq). Dried (NaSO₄) and concentrated to give a red syrup (173 mg). The residue was purified on a silica gel column

(C₂H₅O Ac:CH₃OH:(C₂H₅)3N,4: 1:0.05) giving (3aS-cώ)-l, 2,3,3a,8,8a-hexahydro-l,3a,8- trimethylpyrrolo[2,3-b]indol-5-yl

3,4-dihydro-6,7-dihydroxy-2(lH)-isoquinolinecarboxylate (CVII)(110 mg, 46%).

¹³C-NMR (CDCI₃) d 155.1, 149.3, 144.0, 143.9, 143.7, 137.4, 125.5, 125.4, 124.1, 123.8, 120.7, 116.3, 115.0, 114.8, 112.7, 106.7, 97.7, 53.0, 52.6, 45.6, 45.4, 42.3, 41.8, 40.2, 38.2, 36.8, 28.2, 27.8, 27,0

MS409 (28,M⁺),218 (79),217 (100), 161 (66), 160(86)

Biological Experiment 1

Determination of the inhibition of electric eel AChE activity.

Principle: AChE catalyses the hydrolysis of acetylthiocholine. The product, thiocholine, reacts with 4,4'-dithiopyridine to form 4-thiopyridone. The rate of formation of 4- thiopyridone is followed spectrophotometrically at 324 nm. The registration is continuous, and the rate of formation of 4-thiopyridone is recorded.

Apparatus, chemicals and reagents: AChE from electric eel. A stock solution of 20 U/ml is prepared in phosphate buffer, pH 7.4, and portioned into 3 ml vials and kept at -18° C until the time of analysis. On each day of analysis, a new sample is slowly thawed on ice and kept on ice until time for incubation.

Solutions of the test and reference substances were stock solutions of 20 ±1 μM in sodium phosphate buffer pH 2.5. Incubation procedure for determining the 50% inhibitory concentration (IC50): All activities are calculated as % of zero time value and with correction made for the decrease in activity for AChE in blanks during the incubation. In a 3 ml glass tube: 0.05 M sodium phosphate buffer pH 7.4, AChE (electric eel) 1 U/ml and test substance in concentrations ranging from 0.26 nM to 121 μM in a final volume of 2 ml. The initial AChE activity is determined and the tube is placed in a water bath at 37°C. After 180 min the AChE activity is measured again. Results are expressed as IC50 values, the concentration giving 50% inhibition of the enzyme activity.

Spectrophotometrical analysis: All measurements were carried out in 1.5 ml plastic cuvettes. To 850 μl PDS buffer (0.1 mM 4,4'-dithioρyridine, 37°C), 50 μl of the incubate is added. Recording begins on adding lOOμl 10 mM acetylthiocholine (ASCh). The absorbance is followed at 324 nm for 2 min and the results are calculated from the difference in absorbance per minute (ΔA/min) values.

Measurement of spontaneous hydrolysis: A cuvette filled with 900 μl of 37°C 4,4'- dithiopyridine (PDS) is placed in the spectrophotometer. 100 μl of 10 mM ASCh is added and recording begins.

The compounds may also be tested in vitro for AChE inhibitory activity in brain homogenate from rat according to the following experiment

Biological experiment 2 Determination of inhibition of rat brain AChE

The materials and method were the same as described in Biological experiment 1 except that in the 3 ml glass tube 20 μl of stock solution (20 ±1 μM) of substance is added to brain homogenate giving a final volume concentration of 200 nM of the substance. Results were recorded as % of control enzyme activity at 30, 60, 120 and 180 minutes, the control being incubation of rat brain homogenate without test substance. Thus, a low figure of AChE activity means that the substance is effective as an inhibitor of AChE.

Sample preparation of brain homogenate: Brain from Sprague-Dawley rat is weighed and homogenised in 19 parts of phosphate buffer 0.05 M, pH 8.0 containing 0.1% Triton X-100 (t-octyl phenoxypolyethoxyethanol) by use of a Heidolph Elektro homogenizer. The homogenate is transferred to plastic vials and kept on ice until analysed (within 10 min.). After analysis the vial is kept at -80 °C .

The title compounds of Examples 1 to 4 were tested according to Biological Experiments 1 and 2 and were all found to be active.

Claims

1. The 3aS-cis and 3&R-cis isomers of a compound ofthe formula

wherein R* and R₂ , which may be the same or different are each is H or CH₃, and

R₃ is H or OH,

R4 and R5 , which may be the same or different, are each H, OH or OCH3,

provided that

a) at least one of R. and R₂ is H when R₃ , R4 and R5 all are H,

b) when Ri and R₂ are both CH₃ and R₃ is OH, then R4 and R5 are both H,

c) when R* and R₂ are both CH₃ and R₃ and R4 are both H, then R5 is OH in position 5 of the isoquinolyl moiety ofthe molecule,

d) when R\ and R are both CH3 , and R3 is H, then R4 and R5 are either both OH or both OCH3 in positions 6 and 7 ofthe isoquinloyl moiety ofthe molecule,

racemic mixtures and any other mixture thereof, and pharmaceutically acceptable acid addition salts thereof.

SUBSTITUTE SHEET

2. Compounds according to claim 1, which are 3aS isomers.

3. Compounds according to claim 1, which are 3aR isomers.

4. The compound according to any of claims 1 or 2, which is

(3 aS-cis)- 1,2,3, 3 a,8, 8a-hexahydro- 1 ,3 a-dimethylpyrrolo[2,3 -6]indol-5 -yl 3 ,4-dihydro- 2( lH)-isoquinolinecarboxylate,

(3aS-cts)-l,2,3,3a,8,8a-hexahydro-3a,8-dimethylpyrrolo[2,3-£]indol-5-yl 3,4-dihydro- 2( lHHsoquinolincarboxylate,

(3aS-c/5)-l,2,3,3a,8,8a-hexahydro-l,3a,8-trimethylpyrrolo[2,3-έ]indol-5-yl 3,4-dihydro-4- hydroxy-2( 1 H)-\ soquinolinecarboxylate,

(3a5-c/5)-l,2,3,3a,8,8a-hexahydro-l,3a,8-trimethylpyrrolo[2,3-6]indol-5-yl 3,4-dihydro-5- hydroxy-2(lH)-isoquinolinecarboxylate,

(3aS- s)-l,2,3,3a,8,8a-hexahydro-l,3a,8-trimethylρyrrolo[2,3-i]indol-5-yl 3,4-dihydro- 6, 7-dimethoxy-2( 1 H)-isoquinolinecarboxylate,

(3aS-cw)-l,2,3,3a,8,8a-hexahydro-l,3a,8-trimethylpyrrolo[2,3-*]indol-5-yl 3,4-dihydro-6,7- dihydroxy-2( 1 //)-isoquinolinecarboxylate,

(3a.S^'-c/5)-l,2,3,3a,8,8a-hexahydro-3a-methylρyrrolo[2,3-6]indol-5-yl 3,4-dihydro-2(lH)- isoquinolinecarboxylate.

5. A pharmaceutical composition comprising as active ingredient a compound as defined in any of claims 1 to 4.

SUBSTITUTE SHEET

6. A pharmaceutical composition for oral administration comprising as active ingredient a compound as defined in any of claims 1 to 4.

7. A pharmaceutical composition for parenteral administration comprising as active ingredient a compound as defined in any of claims 1 to 4.

8. A compound according to any of claims 1 to 4 for use in therapy.

9. A compound according to any of claims 1 to 4 for use in the treatment of diseases characterized in a cholinergic deficit.

10. A compound according to any of claims 1 to 4 for use in the treatment of diseases characterized in memory dysfunction.

1 1. A compound according to any of claims 1 to 4 for use in the treatment of Alzheimer's disease.

12. Use of a compound according to any of claims 1 to 4 for the preparation of a medicament for alleviating a cholinergic deficit.

13. Use of a compound according to any of claims 1 to 4 for the preparation of a medicament for alleviating memory dysfunction.

14. Use of a compound according to any of claims 1 to 4 for the preparation of a medicament for alleviating Alzheimer's disease.

15. A method of treating a patient in need of alleviation of a cholinergic deficit, which method comprises administering to such a patient an effective amount of a compound as defined in any of claims 1 to 4.

SUBSTITUTE SHEET

16. A method of treating a patient in need of alleviation of memory dysfunction, which method comprises administering to such a patient an effective amount of a compound as defined in any of claims 1 to 4.

17. A method of treating a patient in need of alleviation of Alzheimer's disease, which method comprises administering to such a patient an effective amount of a compound as defined in any of claims 1 to 4.

18. A process for manufacturing a compound according to claim 1, wherein R-, R₃, R4, and R5 all are H and R₂ is CH₃, characterized in treating (3a- )-8-formyl-l,2,3,3a,8,8a- hexahydro-l,3a-dimethylpyrrolo[2,3-i]indol-5-yl 3,4-dihydro-2(lH)isoquinolinecarboxylate with a strong acid in aqueous solution.

19. A process for manufacturing a compound according to claim 1, wherein R₂, R₃, R4, and R5 all are Η, and R- is CΗ₃, characterized in treating (3a-cw)-l,2,3,3a,8,8a-hexahydro-

3a,8-dimethylpyrrolo[2,3-i]indol-5-yl 3,4-dihydro-2( lH)-isoquinolinecarboxylate with hydrogen in the presence of a palladium catalyst.

20. A process for manufacturing a compound according to claim 1 wherein Ri and R₂ are both CH₃ , R4 and R5 are H, and R₃ is OH in position 1, 3 or 4 ofthe isoquinoline moiety ofthe molecule, characterized in reacting eseroline with carbonyldiimidazole and 1,2,3,4- tetrahydro-hydroxyisoquinoline.

21. A process for manufacturing a compound according to claim 1, wherein R- and R₂ both are CH₃, R3 is H, and one of R or R5 is OH in any of positions 5, 6, 7, or 8 ofthe

isoquinoline moiety ofthe molecule the other substituent of R4 or R5 being H , characterized in demethylating (3a-c/s)-l,2,3,3a,8,8a-hexahydro-l,3a,8- trimethylpyrrolo[2,3-i]indol-5-yl 3,4-dihydro-methoxy-2(l//)-isoquinolinecarboxylate

SUBSTITUTE SHEET having the methoxyl group in any of positions 5, 6, 7, or 8 if the isoquinoline moiety ofthe molecule with a mineral acid or a Lewis acid.

22. A process for manufacturing a compound according to claim 1, wherein R\ and R2 both

are CH3, R3 is H, and R4 and R5 are both methoxy characterized in treating eseroline with carbonyldiimidazole.

23. A process for manufacturing a compound according to claim 1, wherein Rj and R2 both

are CH3, R3 is H, and R4 and R5 are both hydroxy characterized in treating the hydrochloride salt of (3aS-c/^'5')-l,2,3,3a,8,8a-hexahydro-l,3a,8-trimethylpyrrolo[2,3- &]indol-5-yl 3,4-dihydro-6,7-dimethoxy-2(lH)-isoquinolinecarboxylate with boron tribromide and triethylamine.

24. (3a-c;^'Λ')-l-formyi-l,2,3,3a,8,8a-hexahydrυ-3a,8-dimethylpyrrolo[2,3-i]indol-5-yl 3,4- dihydro-2(l /)-isoquinolinecarboxylate.

25. (3a-c/5)-l,2,3,3a,8,8a-hexahydro-l-benzyl-3a,8-dimethylpyrrolo[2,3-i]indol-5-yl 3,4- dihydro-2( 1 H)isoquinolinecarboxylate.

26. (3a-c/5)-l,2,3_>3a,8,8a-hexahydro-l,3a,8-trimethylpyrrolo[2,3- >]indol-5-yl 3,4-dihydro- methoxy-2(lH)-isoquinolinecarboxylate having the methoxyl substituent in any of positions 5, 6, 7, or 8 ofthe isoquinolyl moiety ofthe molecule.

SUBSTITUTE SHEET