NO180445B - 2- (4-hydroxypiperidino) -1-alkanol derivatives as anti-ischemic agents - Google Patents

Description

The present invention relates to neuroprotective (anti-ischemic, excitatory amino acid receptor-blocking) 2-(4-hydroxypiperidino)-1-alkanol derivatives of formula (I) below; pharmaceutically acceptable salts thereof; preparations containing these for use in the treatment of stroke, traumatic brain and spinal cord injury, and neuronal degenerative diseases including (but not limited to) senile dementia such as Alzheimer's disease, Huntington's disease and Parkinson's disease in mammals, especially humans; as well as certain intermediate products for these.

Ifenprodil (A) is a racemic, so-called dl-erythro compound with the relative stereochemical formula

which is marketed as a hypotensive agent, an application which also applies to a number of close analogues. Carron et al, US Patent 3,509,164; Carron et al., Drug Res., v. 21, pp. 1992-1999 (1971). More recently, ifenprodil has been shown to have anti-ischemic and excitatory amino acid receptor-blocking activity. Gotti et al., J. Pharm. Exp. Therap., v. 247, pp. 1211-21 (1988);. Carter et al., loe.eit., pp. 1222-32 (1988).

See also French patent 2546166 and EPO publication EP-A1-351282, published January 17, 1990. An objective, essentially achieved by the present invention, has been to find compounds with a high degree of neuroprotective activity, while at the same time time has a reduced or negligible hypotensive effect.

Certain 1-phenyl-3-(4-aryl-4-acyloxy-piperidino)-1-propanols are also indicated to be useful as analgesics, US Patent 3,294,804; 1-[4-(amino- and hydroxy-alkyl)phenyl]-2-(4-hydroxy-4-tolylpiperazino)-1-alkanols and alkanones are reported to have analgesic, antihypertensive, psychotropic or anti-inflammatory activity, Japanese Kokai 53-02,474 (CA

89:43498y; Derwent Abs. 14858A) and 53-59,675 (CA 89:146938w; Derwent Abs. 48671A); and 2-piperidino-1-alkanol derivatives are reported to be active as anti-ischemic agents, EP 398,578-A and Der 90-350,327/47.

Summary of the invention

The present invention relates to compounds with the formula

and pharmaceutically acceptable salts thereof; wherein R 17 R 2 and R 3 are each selected from the group consisting of hydrogen and alkyl of 1 to 6 carbon atoms; n is 1 or 2; and M and Q together form a divalent radical Z, where Z is selected from the group consisting of

The term "pharmaceutically acceptable salts" shall include, but is not limited to, such salts as hydrochloride, hydrobromide, hydroiodide, nitrate, hydrogen sulfate, dihydrogen phosphate, mesylate, maleate, and succinate. Such salts are prepared in the usual manner by reacting the free base form of compound (I) with a suitable acid, usually one molar equivalent, in a solvent. The salts which do not precipitate directly are usually isolated by evaporation of the solvent and/or addition of a non-solvent followed by filtration.

A preferred group of compounds according to the present invention is that where M and Q form a radical Z, where

Z is

Ri and R2 are hydrogen and R3 is methyl, and the compounds have lr<*>,2s<*> or erythro-relative stereochemistry in the 1- and 2-positions of the propanol chain, i.e. A second preferred group of compounds according to the invention is the where M and Q form a radical Z, where Z is Ri and R2 is hydrogen and R3 is methyl, and the compounds have ls<*>,2s<*> or threo-relative stereochemistry in the 1- and 2-positions of the propanol chain , i.e.

The present invention also relates to pharmaceutical preparations containing a compound according to the invention with formula I. The compounds and the preparations containing these can be used for the treatment of a mammal, especially a human, suffering from a central nervous system disorder, which comprises the administration of a neuroprotective amount of a compound of formula (I) to the mammal. The preparations are particularly valuable for the treatment of traumatic damage to the brain and spinal cord, stroke, Alzheimer's disease, Parkinson's disease, Huntington's disease and related disorders of the central nervous system.

The present invention further relates to intermediate products with the formula

where

R 2 and R 3 are each selected from the group consisting of hydrogen and alkyl of 1 to 6 carbon atoms;

n is 1 or 2;

and M and Q together form a divalent radical Z, where Z is selected from the group consisting of

Depending on the relevant meaning of R 1 R 2 and R 3 , the compounds of formula (I) may have one or two asymmetric centers, and may therefore exist in different isomeric forms. All such isomers are covered by the present invention. The individual isomers can be separated by classical methods well known to those skilled in the art.

Detailed description of the invention

The compounds according to the present invention with formula (I) stated above are easily and generally prepared by reacting the chlorine compound (II) with the piperidine (III), followed by reduction of the resulting ketone (IV) to an alcohol as described below.

The precursor ketones are usually first prepared with -OH- and

The -NH2 substituents in protected form, i.e. as -QA1 or -NHA2 groups in the compounds of formula (IV). A^ and A2 are defined below. Such protected ketones are usually formed by reacting a suitably substituted 2-halo-1-alkanone (II) with a suitably substituted piperidino derivative (III), e.g. Reaction of compound (II) with compound (III) is carried out under conditions typical of nucleophilic substitution in general. When the two reaction components are approximately equivalent in availability, near substantially molar equivalents may be used, although, if one is more readily available, it is normally preferred to use this in excess, to force this bimolecular reaction to completion in a shorter time . The reaction is usually carried out in the presence of at least 1 molar equivalent of base, the piperidine derivative itself, if readily available, but usually a tertiary amine at least comparable to the nucleophilic piperidine in base strength; in a reaction inert solvent such as ethanol. If desired, the reaction can be catalyzed by the addition of up to one molar equivalent or more of an iodide salt (eg Nal, Kl). The temperature is not critical, but will normally be somewhat elevated to force the reaction to end in a shorter time, but not so high that it leads to unwanted decomposition. A temperature in the range 50-120°C is usually satisfactory. Conveniently, the temperature is the reflux temperature of the reaction mixture.

As used in the preceding paragraph and elsewhere in the specification, the term "reactionable solvent" refers to any solvent that does not affect the starting materials, reagents, intermediates, or products in a manner that adversely affects the yield of the desired product.

If desired, the ketone intermediates (IV) which have OH or NH2 groups in protected form (OHAX or NHA2) can at this point be deprotected by usual methods.

When Ax e.g. is triisopropylsilyl or tert-butyldimethylsilyl, the protecting group is conveniently removed by reaction with tetrabutylammonium fluoride (typically, substantially 2 mole equivalents) in a reaction-inert solvent such as tetrahydrofuran. When Aj. is benzyl or A 2 is benzyloxycarbonyl, the protecting group is usually removed by conventional hydrogenolysis over a noble metal catalyst in a reaction-inert solvent, e.g. using 10% Pd/C as catalyst, preferably at low pressures (eg 1-10 atmospheres) and temperatures (eg 20-75°C) and usually in a reaction-initiated solvent such as methanol.

In general, the ketone intermediates (IV) are conveniently converted to the corresponding alcohols by one of two common reduction methods, to selectively provide either the threo compounds or the erythro compounds of formula (I).

As used above and elsewhere in the specification, the designation "treo" or lr<*>,2s<*> indicates the relative stereochemistry of the 1- and 2-positions of the propanol chain, i.e. and the designation "erythro" or lr<* >,2s<*> indicates the relative stereochemistry in the 1- and 2-positions of the propanol chain, i.e.

To obtain the desired erythro compounds by formula

(I) the corresponding ketone intermediates (IV) are suitably reduced with potassium borohydride, usually in excess (e.g. more than 5 molar equivalents), in the presence of glacial acetic acid in a protic solvent such as ethanol, usually at a temperature in the range 15-25°C.

To obtain the desired threo compounds of formula (I), the corresponding ketone intermediates (IV) are suitably reduced with sodium borohydride, usually in excess (e.g., more than 5 mole equivalents) in a protic solvent such as ethanol, generally at a temperature in the range of 15-25°C. The resulting reaction mixture is chromatographed on a silica gel column to obtain the threo compounds of formula (I).

Protecting groups that may still be present after the ketone reduction are then removed according to standard methods described above.

The starting materials and reagents necessary for the synthesis of the compounds according to the present invention are readily available, either commercially, according to methods described in the literature, or by the methods illustrated in the Preparations below.

The present compounds of formula (I) have selective neuroprotective activity, based on their anti-ischemic activity and the ability to block excitatory amino acid receptors, while at the same time having reduced or negligible hypotensive activity. The anti-ischemic activity of the present compounds is determined according to one or more methods previously described by Gotti et al and Carter et al, cited above, or by similar methods.

The ability of the compounds of the present invention to block excitatory amino acid receptors is demonstrated by the drug's ability to rescue fetal rat neurons in a culture that has been exposed to excitotoxic amino acid glutamate. The following method is typical.

Part I: Cell Isolation:

After 17 days of gestation, embryos are removed from rats and placed in Tyrode's solution. The brain is then removed and placed in fresh Tyrode's solution. Using fine iris knives, the cerebellum and thalamus are removed. The cerebrum is then divided into two hemispheres. The opinions are then carefully removed. The hippocampus appears as a dark, folded area on the inside edge of the cortex. The hippocampus is carefully cut away from the rest of the tissue and placed in a separate corner of the dish. When the dissection is complete, the hippocampal tissue in the corner is minced into 1 mm pieces. These pieces are removed using a Pasteur pipette and placed in a sterile tube. Tyrode's solution is carefully aspirated from, and calcium-magnesium-free Tyrode's solution is added. The tissue is washed 3 times with calcium-magnesium-free Tyrode's solution. The last wash is incubated for 15 minutes at 37°C. The buffer is removed again and replaced with 1 ml of fresh calcium-magnesium-free Tyrode's solution. Trypsin is now added as 0.1% (100 µl of a 10 mg/ml sterile stock solution). The tube is incubated for 1 hour at 37°C. After the trypsin incubation, the tissue is washed with serum-containing medium to stop the effect to the trypsin. The tissue is resuspended in 1 ml of fresh medium and scraped out with a fine Pasteur pipette. The cells are then counted using a hemocytorneter. The cells are then seeded onto 96-well Falcon Primeria tissue culture plates with 75,000 cells per well. well in complete medium. Complete medium is composed of Minimal Essential Medium (MEM) with Earle's salts, 10% fetal calf serum (Hyclone), 10% horse serum, L-glutamine (2mM), penicillin-streptomycin (100U per ml) and glucose (to making the final concentration 21 mM, a 100x stock containing 27.8 g per 100 ml is prepared). On day 3, the plates were supplied with fresh medium. On day 6, 10 µl cytosine arabinoside is then added to the cultures with fresh medium. 2 days later, the cytosine arabinoside is then removed and replaced with Maintenance medium, which is complete medium minus the fetal calf serum. The plates are then fed twice a week. Three weeks after the dissection, the plates are used in glutamate toxicity experiments, to ensure proper development of the neurons in the culture.

Part 2: Glutamate treatment and post-glutamate drug addition

After 3 weeks in the culture, the medium is removed from the cells, and the cells are washed three times in chloride-free controlled salt solution (CSS-C1). CSS-C1 contains 69 mM Na2SO4, 2.67 mM K2SO4, 0.33 mM NaHP04, 0.44 mM KH2PO4, 1 mM NaHCO3, 1 mM MgSO4, 10 mM HEPES (N-2-hydroxyethylpiperazine-N1-2-ethanesulfonic acid ), 22.2 mM glucose and 71 mM sucrose at pH 7.4. After washing, glutamate is added as 1 to 3 mM in CSS-C1 buffer with suitable control wells containing buffer without glutamate. The plates are incubated at 37°C for 15 to 20 minutes. After the glutamate incubation, the plates are washed twice with serum-free medium. The test drug is prepared in suitable concentrations in serum-free medium and added to the corresponding wells in the microtiter plate (100 µl per well). Negative control wells receive serum-free medium without drug. Several glutamate-treated wells also receive serum-free medium without drug to serve as positive controls. The plate is incubated overnight at 37°C, and the following day the viability is determined using LDH (lactate dehydrogenase) and MTT (methylthiotetrazolinium) tests.

Part 3: Determination of cell viability

100 µl medium from each plate is removed and transferred to a clean plate to determine the amount of LDH released. Then 100 µl MTT solution is added per well. This MTT solution is prepared by adding 10 µl of MTT stock (5 mg/ml in PBS, phosphate-buffered saline) to every 100 µl of serum-free medium. The plates are incubated at 37°C for 4-6 hours. Then 100 µl acid-alcohol solution (0.08N HCl in isopropanol) is added to each well, and the wells are mixed vigorously to dissolve the purple crystals. The control wells must contain medium with MTT and acid alcohol, but no cells.

The plates are then read on a microplate reader, using a dual wavelength setting with a test filter at 570 nm and a reference filter at 630 nm. The plates must be read within 1 hour.

The withdrawn medium is then tested for LDH. Equal parts of the taken samples are added to the LDH reaction mixture. In this case, appropriate wells are pooled to yield 500 µl samples. For each sample, the reaction mixture is prepared by mixing 480 µl of 0.1 M sodium phosphate buffer, pH 7.5, 10 µl of sodium pyruvate (66 mM) and 10 µl of reduced NADH (each bottle of NADH containing 5 mg is reconstituted in 440 µl 0.1N NaOH and 10 µl of this is used per sample). The sample is quickly added to the reaction mixture in small dishes, and the loss of absorbance at 340 nm is measured on a Beckman DU-8 spectrophotometer. In this way, the ability of the compounds to inhibit the N-methyl-D-aspartate (NMDA) receptor sites is determined, with the following result:

c

Unwanted hypotensive activity is also determined by known methods, e.g. by the methods of Carron et al, also referred to above.

Such selective neuroprotective anti-ischemic and excitatory amino acid blocking activity makes the compounds of the present invention useful for the treatment of traumatic brain and spinal cord injury, degenerative CNS (central nervous system) disorders such as stroke, Alzheimer's disease, Parkinson's disease and Huntington's disease, without potential of importance for simultaneous unwanted drop in blood pressure. In the systemic treatment of such diseases in humans with a neuroprotective amount of the compounds of formula (I), the dose is typically from approx. 0.02 to 10 mg/kg/day (1-500 mg/day in a human weighing 50 kg) in single or divided doses, regardless of the route of administration. Depending on the exact compound and the exact type of the individual disease, doses outside this range can of course be prescribed by the attending physician. The oral route of administration is usually preferred. However, if the patient is unable to swallow, or oral absorption is otherwise impaired, the preferred route of administration is parenteral (i.m., i.v.) or topical.

The compounds according to the invention are usually administered in the form of pharmaceutical preparations comprising at least one compound of formula (I) together with a pharmaceutically acceptable carrier or diluent in a ratio of 1:20 to 20:1. Such preparations are usually formulated in a conventional manner using solid or liquid carriers or diluents, depending on what is appropriate for the route of administration in question: for oral administration in the form of tablets, hard or soft gelatin capsules, suspensions, granules, powders and the like, - for parenteral administration, in the form of injectable solutions or suspensions and the like, and for topical administration, in the form of solutions, lotions, ointments, creams and the like.

The present invention is illustrated by the following examples, but is not limited to the details thereof.

All non-aqueous reactions were performed under dry, oxygen-free nitrogen for practical reasons and to generally maximize yields. All solvents/diluents were dried according to standard described methods or acquired in pre-dried form. All reactions were stirred either magnetically or mechanically. NMR spectra are recorded at 300 MHz and are indicated in ppm precipitated from trimethylsilane. The NMR solvent was CDCl 3 unless otherwise noted. IR spectra are indicated in micrometres, and normally only strong signals are indicated.

Example 1

(+)- 3. 4- dihydro- 6-( l- hydroxy- 2-( 1-( 4- hydroxy- 4- phenoxy-methyDpperidinyl) ethyl) quinolin- 2-( 1H) - one

A mixture of 300 mg (1.23 mmol) 4-hydroxy-4-(phenoxy-methylpiperidine hydrochloride), 409 mg (1.84 mmol) 6-(2-chloroacetyl)-3,4-dihydroquinoline-2(1H) -one and 0.514 mL (0.373 g, 3.7 mmol) of triethylamine in 25 mL of acetonitrile were heated at 60° C. overnight. The solvent was then removed in vacuo, the residue was partitioned between water and ethyl acetate, and the organic layer was washed again with water and brine.The ethyl acetate layer was dried with brine and magnesium sulfate, and the solvent was evaporated to give 3,4-dihydro-6-(1-oxo-2-(1-(4-hydroxy-4- phenoxymethyl)-piperidinyl)ethyl)quinolin-2-(1H)-one as a brown solid which was used in the subsequent reduction step without further purification.

The above ketone was dissolved in 25 ml of absolute ethanol, and 500 mg (13.1 mmol) of NaBH 4 was added portionwise over 20 minutes. The reaction mixture was stirred at room temperature for 4 hours, and the solvent was then removed and the residue partitioned between water and ethyl acetate. After drying, the ethyl acetate was removed in vacuo and the residue chromatographed on silica gel to give the product, 73 mg (15%), m.p. 186-188°C. NMR (CD 3 OD) a 1.70-2.10 (4H, m), 2.52-3.07 (10H, m), 3.33 (2H, s) , 3.83 (2H, s) , 6 .82-7.38 (8H, m) .

Example 2

(+)- 5-( 1- hydroxy- 2-( 1-( 4- hydroxy- 4- phenoxymethyl)-piperidinyl) ethyl) benzimidazolin- 2- one

Following the procedure of Example 1, the title compound was obtained from 4-hydroxy-4-(phenoxymethyl)piperidine hydrochloride (1.23 mmol), 5-(2-chloroacetyl)-2-hydroxybenzimidazole (1.84 mmol) and triethylamine (3.7 mmol) in 25 ml of acetonitrile. The resulting ketone was stirred with sodium borohydride (13.1 mmol) in absolute ethanol to give the desired compound after chromatography on silica gel. Yield 35%, sm.p. 232-235°C.

Analysis for C21H25N304. H20:

Calculated: C 62.81; H 6.77; N 10.46

Found: C 62.98; H 6.54; N 10.32.

Example 3

(+)- 5-( 1- hydroxy- 2-( 1-( 4- hydroxy- 4- phenoxymethyl)-piperidinyl) ethyl)- 2- oxindole

By following the procedure in Example 1, the title compound was obtained from 4-hydroxy-4-(phenoxymethyl)piperidine hydrochloride (1.23 mmol), 5-(2-chloroacetyl)oxindole (1.84 mmol) and triethylamine (3.7 mmol) in 25 ml of acetonitrile. The resulting ketone was stirred with sodium borohydride (13.1 mmol) in absolute ethanol to give the desired compound after chromatography on silica gel. Yield 40%, sm.p. 171-174°C.

Example 4

(+)- erythro- 5-( l- hydroxy- 2-( 1-( 4- hydroxy- 4- phenoxymethyl)-piperidinyl) propyl) benzimidazolin- 2- one

A solution of 933 mg (2.36 mmol) (±)-1-(5-(2-hydroxy-benzimidazolyl))-2-(1,-(4-hydroxy-4-phenoxymethyl)piperidinyl)-propane-1 -one in 10 ml of glacial acetic acid and 50 ml of absolute ethanol was treated portionwise with 944 mg (17.48 mmol) of potassium borohydride between 15 and 20°C, and the resulting solution was stirred overnight at room temperature. The reaction mixture was then evaporated to dryness and the residue taken up in a minimal amount of water. The pH of the solution was adjusted to 7-8 with solid NaHCO 3 , which precipitated a solid. This material was insoluble in chloroform and relatively insoluble in ethyl acetate. The whole was again evaporated to dryness, and the residue, which had crystallized, was taken up in ethanol and filtered to remove salts. The ethanol was evaporated, and the residue was taken up in isopropanol and treated with HCl gas in ether, which precipitated a non-crystalline salt which was separated by filtration and dried in a stream of dry nitrogen. This material was dissolved in hot ethyl acetate with methanol and clarified with decolorizing charcoal, and the methanol was then boiled off. Cooling gave a colorless crystalline product, 410 mg (40%), m.p. 254-255°C.

IR (KBr) 5.90 /mi;

NMR (CD 3 OD) δ 1.22 (3H, d, J=7), 1.95-2.09 (2H, m), 2.15-2.30 (2H, m), 3.42-3, 76 (4H, m), 3.91 (2H, s), 5.47 (1H, s), 6.92-7.35 (8H, m).

Example 5

( + )- threo- 5-( l- hydroxy- 2-( 1-( 4- hydroxy- 4- phenoxymethyl)-piperidinyl) propyl) benzimidazolin- 2- one

A total of 700 mg (18.4 mmol) of sodium borohydride was added portionwise to a suspension of 325 mg (0.82 mmol) (+)-1-(5-(2-hydroxybenzimidazolyl)-2-(1-(4-hydroxy- 4-phenoxymethyl)-piperidinyl)propan-1-one in 20 mL of absolute ethanol, and the reaction mixture was stirred overnight at room temperature.The solvent was then evaporated, and the remaining foam was taken up in ethyl acetate and water, and the aqueous layer was extracted with ethyl acetate The combined ethyl acetate extracts were dried and evaporated and the residual foam was chromatographed on silica gel using 1:1 ethanol/ethyl acetate to give the product as a white solid, mp > 250°C .

NMR (acetone-d6) 6 0.79 (3H, d, J=7) , 1.71-1.88 (2H, m) , 11.90-2.08 (2H, m), 2.48- 2.88 (4H, m), 3.01 (1H, t, J=7), 3.88 (2H, S) , 4.26 (1H, d, J=7) , 6.86-7, 32 (8H, m) ;

Analysis for C22H27N304.1, 5 H2O:

Calculated: C 62.24; H 7.12; N 9.89

Found: C 61.72; H 6.73; N 9.03.

Example 6

(+ )- erythro- 3. 4- dihydro- 6-( l- hydroxy- 2-( 1-( 4- hydroxy- 4-phenoxymethyl) piperidinyl) propyl) quinolin- 2( 1H)one

A solution of 7.13 g (17.5 mmol) (±)-1-(6-(1,2,3,4-tetrahydro-2-oxoquinolinyl))-2-(1-(4-hydroxy-4 -phenoxymethyl)-piperidinyl)propan-1-one in 135 ml of absolute ethanol and 70 ml of glacial acetic acid was treated in portions with 6.22 g (115 mmol) of KBH4 at 15-20°C, and was then allowed to warm to room temperature for 30 minutes. The reaction mixture was evaporated to dryness, and the residue was taken up in ice and cold water and basified with solid NaHCO 3 . The solid which precipitated was separated by filtration, washed with water and air dried to give 3.66 g of crystalline free base, m.p. 192-196°C. The filtrate was extracted with ethyl acetate, and the combined extracts were dried with brine and MgSO 4 and evaporated to give an additional 786 mg of product (total yield 62%). A 510 mg sample of this material was dissolved in ethyl acetate and treated with a solution of HCl gas in ether to give 475 mg of the crystalline hydrochloride salt, m.p. 214-216°C (dec.)..

IR (KBr) (im;

NMR (CD 3 OD) 3 1.15 (3H, d, J=7), 1.86-2.04 (2H, m), 3.52-3.66 (2H, m), 3.69-3, 80 (1H, m), 3.86 (2H, s), 5.34 (1H, s), 6.81-6.96 (4H, m), 7.17-7.28 (4H, m) .

Example 7

(+)- threo- 3. 4- dihydro- 6-( l- hydroxy- 2-( 1-( 4- hydroxy- 4- phenoxymethyl) piperidinyl) propyl) quinolin- 2( 1H) one

A total of 1.50 g (39.5 mmol) NaBH4 was added portionwise to a suspension of 700 mg (1.71 mmol) (±)-1-(5-(2-hydroxybenz-imidazolyl))-2-(1- (4-Hydroxy-4-phenoxymethyl)piperidinyl)-propan-1-one in 20 ml of absolute ethanol, and the reaction mixture was stirred overnight at room temperature. The solvent was then evaporated, and the remaining foam was taken up in ethyl acetate and water, and the aqueous layer was extracted with ethyl acetate. The combined extracts were dried and evaporated and the remaining foam was chromatographed on silica gel using 1:1 ethanol/ethyl acetate to give the product as a white solid, m.p. 192-196°C. A small amount of the erythro compound was formed by this reduction and could be separated from the column.

NMR (CD 3 OD) a 0.82 (3H, d, J=7) , 1.72-2.06 (4H, m) , 2.50-2.82 (6H, m), 2.88-3, 02 (2H, t, J=7), 3.02 (1H, t, J=7), 3.84 (2H, S) , 4.28 (1H, d, J=7) , 6.80- 7.34 (8H, m);

Analysis for C22H27N304.1, 5 H2O:

Calculated: C 65.88; H 7.60; N 6.40

Found: C 65.74; H 7.09; N 6.31.

Example 8

( + ) - erythro- 5 - ( l - hydroxy - 2 - ( 1 - ( 4 - hydroxy - 4 - phenoxymethyl) - piperidinyl) propyl) oxindole

A mixture of 0.5 g (2.05 mmol) 4-hydroxy-4-phenoxymethyl)piperidine hydrochloride, 0.5 g (2.25 mmol) 5-(2-chloropropionyl)oxindole and 1 ml (0.725 g, 7.18 mmol) of triethylamine in 20 ml of acetonitrile was refluxed for 24 hours. The solvent was then removed in vacuo and the residue partitioned between ethyl acetate and water. The ethyl acetate layer was washed with water and brine and was dried over MgSO 4 and concentrated to give the ketone as a tan foam which was used in the following reaction without further purification, 537 mg (66%).

A solution of 500 mg (1.26 mmol) of the ketone in 20 mL of ethanol was treated portionwise with 1.0 g (26.3 mmol) of NaBH 4 , and the resulting mixture was stirred at room temperature for 24 h. The solvent was removed in vacuo and the residue partitioned between ethyl acetate and water. The ethyl acetate layer was washed and dried with brine and MgSO 4 and then evaporated to dryness. The residue was chromatographed on silica gel using ethyl acetate and gradually increasing concentrations of ethanol to give the threo product in pure fractions, 121 mg (24%), m.p. 204-207°C.

NMR (DMSO-d6) δ 0.70 (3H, d, J=7) , 1.58-1.92 (4H, m) , 2.40-2.65 (4H, m), 2.86 ( 1H, m), 3.32-3.40 (2H, m), 3.79 (2H, s), 4.20 (1H, d, J=7), 6.70-7.35 (8H, m), 10.34 (1H, p).

Example 9

(+)- 1-( 6-( 1. 2. 3. 4- tetrahydro- 2- oxoquinolinyl))- 2-( 1-( 4-hydroxy- 4- phenoxymethyl) piperidinyl) propan- l- one

A suspension of 8.30 g (34.06 mmol) of 4-hydroxy-4-phenoxymethylpiperidine hydrochloride and 8.09 g (34.06 mmol) of 6-(2-chloro-1-propionyl)-1,2,3 ,4-tetrahydroquinolin-2(1H)-one in 100 mL of acetonitrile was treated with 16.61 mL (12.04 g, 0.12 mol) of triethylamine, and the mixture was heated under reflux for 3 hours and then stirred overnight at room temperature.

The reaction mixture was poured into water and extracted 3 times with ethyl acetate, and the combined extracts were dried with brine and magnesium sulfate and evaporated to give a foam. This foam was dissolved in hot methanol and ethyl acetate and cooled to give a tan solid which was found to be the chloroketone starting material <p>g was discarded. The filtrates were evaporated and dissolved in ethyl acetate, and ether was added to facilitate crystallization. The product was filtered and washed with ether, yielding 8.84 g (63.6%) of the product as a cream-colored solid, m.p. 137-139°C. The analytical sample was crystallized from hot ethyl acetate.

NMR (CD3OD) δ 1.28 (3H, d, J=7), 1.60-1.92 (4H, m), 2.52-2.84 (6H, m), 3.00 (2H, t, J=7), 3.75 (2H, s), 4.22 (1H, q, J=7), 6.82-7.00 (4H, m), 7.16 (2H, m) , 7.82-7.98 (2H, m);

Analysis for C24H28N204:

Calculated: C 70.56; H 6.91; N 6.86

Found: C 70.16; H 6.78; N 6.76.

Example 10

( + ) - 1-( 5-( 2- hydroxybenzimidazolyl))- 2-( 1-( 4- hydroxy- 4-phenoxymethyl) piperidinyl) propan- 1- one

A suspension of 2.43 g (10.0 mmol) of 4-hydroxy-4-phenoxymethylpiperidine hydrochloride and 2.25 g (10.0 mmol) of 5-(2-chloro-1-propionyl)-2-hydroxybenzimidazole in 40 ml of acetonitrile was treated with 4.88 ml (3.53 g, 35.0 mmol) of triethylamine, and the reaction mixture was heated under reflux for 90 minutes and then allowed to stand over a weekend at room temperature.

The reaction mixture was then poured into a mixture of water and ethyl acetate, and the resulting suspended solid was separated by filtration and found to be pure product, 1.15 g after drying. The filtrate was adjusted to pH 7.0 and extracted with ethyl acetate several times to give, after drying with brine and MgSO 4 , a colorless solid which was recrystallized from hot ethyl acetate/methanol to give an additional 560 mg of product (total yield , 43%), m.p. 230-235°C (dec.).

NMR (CD3OD/DMSO-d6) 6 1.29 (2H, d, J=7) , 1.60-1.92 (4H, m) , 2.54-2.84 (4H, m), 3, 77 (2H, s), 4.26 (1H, q, J=7), 6.86-7.10 (6H, m), 7.75-7.92 (2H, m).

Example 11

( + )- 1-( 5-( oxindolyl))- 2-( 1-( 4- hydroxy- 4- phenoxymethyl)-piperidinyl) propan- 1- one

Following the procedure of Preparation 10, the title compound was obtained from 4-hydroxy-4-phenoxymethylpiperidine hydrochloride (10.0 mmol), 5-(2-chloropropionyl)oxindole (10 mmol) and triethylamine (35 mmol) in 50 mL of acetonitrile . The title compound was isolated by crystallization from hot ethyl acetate/methanol to give an amorphous foam. Yield 66.4%.

NMR (CDCl 3 ) δ 1.28 (3H, d, J=7), 1.58-1.78 (4H, m) , 2.40-2.84 (4H, m) , 3.54 (2H, s) , 3.76 (2H, s) , 4.09 (1H, q, J=7) , 6.78-6.96 (3H, m), 7.14-7.26 (2H, m) , 7.84-8.05 (3H, m), 9.52 (1H, wide s), 9.64 (1H, wide s).

Production 1

3. 4-Dihydroquinolin-2-(1H)-one

A slurry of 50.0 g (0.259 mol) o-nitrocinnamic acid in 500 ml of ethanol was treated with 5 teaspoons of Raney Ni and hydrogenated in a Parr shaker overnight at an initial pressure of 3.5 kg/cm<2>. In the morning, the pressure was again increased to 3.5 kg/cm<2>, and the reaction was continued for another 5 hours. The reaction mixture was filtered to remove the catalyst and then washed through a pad of silica gel with a mixture of ethyl acetate and ethanol to remove traces of nickel salts. Evaporation of the filtrate gave the desired product in 57% yield.

NMR (DMSO-d6) 6 2.45 (2H, t, J=7) , 2.87 (2H, t, J=7), 6.87 (2H, d of d, J=7, 7), 7.12 (2H, d of d, J=7, 10), 10.08 (1H, s). Sm.p. 165-166°C.

Manufacturing 2

6-( 2- chloropropionyl)- 3. 4- dihydroquinolin- 2-( 1H)- one

A suspension of 72.5 g (0.544 mol) AlCl 3 in 800 mL CS 2 was stirred under dry N 2 while 14.1 mL (20.0 g, 0.177 mol) of 2-chloropropionyl chloride was added, followed by 20.0 g (0.136 mol ) 3,4-dihydroquinolin-2(1H)-one. The reaction mixture was refluxed for 4 hours, after which time separation of the phases was recorded. The reaction was stopped by pouring the mixture onto ice with vigorous stirring. The pale yellow material that precipitated was separated by filtration, washed with water and dried overnight over P2O5 to give 27.7 g (91%) of the desired product, m.p. 236.5-238°C.

Manufacturing 3

5-(2-chloropropionyl)-2-hydroxybenzimidazole

Following the procedure in Preparation 2, the title compound was obtained from 2-hydroxybenzimidazole (0.136 mol), aluminum chloride (0.544 mol) and 2-chloropropionyl chloride (0.177 mol) in 800 ml of CS2. The title compound was isolated by filtration. Yield 92%, sm.p. 245°, dec.

Analysis for C10H9C1N202:

Calculated: C 53.47; H 4.04; N 12.47

Found: C 54.41; H 4.07; N 13.25.

Manufacturing 4

5-(2-chloropropionyl)oxindole

Following the procedure of Preparation 2, the title compound was obtained from oxindole (0.136 mol), aluminum chloride (0.544 mol) and 2-chloropropionyl chloride (0.177 mol) in 800 mL CS 2 . The title compound was isolated by filtration. Yield 91%, sm.p. 157-158°C.

Manufacturing 5

6-( 2- chloroacetyl)- 3, 4- dihydroquinolin- 2( 1H)- one

Following the procedure of Preparation 2, the title compound was obtained from 3,4-dihydroquinolin-2(1H)-one (0.136 mol), aluminum chloride (0.544 mol) and 2-chloroacetyl chloride (0.177 mol) in 800 mL CS 2 . The title compound was isolated by filtration. Yield 50%, sm.p. 215-216°C.

Manufacturing 6

5-(2-chloroacetyl)-2-hydroxybenzimidazole

Following the procedure of Preparation 2, the title compound was obtained from 2-hydroxybenzimidazole (0.136 mol), aluminum chloride (0.544 mol) and 2-chloroacetyl chloride (0.177 mol) in 800 mL CS 2 . The title compound was isolated by filtration. Quantitative yield, sm.p. 273-275°C (dec.).

Manufacturing 7

5-(2-Chloroacetyl)oxindole

Following the procedure of Preparation 2, the title compound was obtained from oxindole (0.136 mol), aluminum chloride (0.544 mol) and 2-chloroacetyl chloride (0.177 mol) in 800 mL CS 2 . The title compound was isolated by filtration. Yield 90%, sm.p. 236.5-239°C.

Manufacturing 8

4- hydroxy- 4- phenoxymethylpiperidine hydrochloride

Oil-free sodium hydride (2.16 g, 0.09 M) was added to dry dimethyl sulfoxide (250 mL) under nitrogen gas, and the mixture was heated to 60-65°C until a uniform black solution was formed, ca. 1 hour. Then 19.83 g (0.09 M) of trimethylsulfoxonium iodide was added (slightly exothermic reaction), and the mixture was stirred until a brown solution was obtained, approx. 30 minutes. Then a solution of 13.40 g (67.3 mM) of N-t-butyloxycarbonyl-4-piperidone in 50 ml of dimethylsulfoxide was stirred at room temperature for 1 hour. The reaction mixture was then poured into cold water, and the whole was extracted 4x with 100 ml portions of hexane. The combined hexane extracts were backwashed with 50 mL of water and brine, and were dried over magnesium sulfate, filtered and evaporated to give 11.75 g of white crystalline product, 6-t-butyloxycarbonyl-1-oxa-6-azaspiro[2.5 ]octane (78% yield).

Further extraction of the aqueous layers with 3 x 50 ml of hexane gave a further 650 mg of product with a total yield of 82.5%. Sm.p. 57.5-59.5°C;

IR (KBr) 5.90 µm;

NMR δ 1.32-1.48 (2H, m), 1.42 (9H, s), 1.74-1.80 (2H, m), 2.65 (2H, s), 3.31- 3.43 (2H, m), 3.61-3.72 (2H, m);

Analysis for CnHi^NOa:

Calculated: C 61.94; H 8.98; N 6.57.

Found: C 62.05; H 9.09; N 6.58

A solution of 10.37 g (0.11 M) phenol in 100 ml of dry dimethylsulfoxide was treated portionwise with 1.99 g

(82.8 mmol) of oil-free sodium hydride while the temperature was maintained between 20-25°C with a cold water bath. The reaction mixture was then stirred at room temperature for 45 minutes, yielding a gray suspension. 11.75 g (55.2 mmol) 6-t-butyloxycarbonyl-1-

oxa-6-azaspiro[2.5]octane dissolved in 65 ml of dimethylsulfoxide was added dropwise, after which the reaction mixture was heated to 55-60°C for 7 hours and then stirred at room temperature overnight.

The reaction mixture was then poured into cold water and extracted 4x with ether. The combined ether extracts were backwashed with 10% NaOH and brine, dried over magnesium sulfate and evaporated to give the desired product, N-t-butyloxycarbonyl-4-hydroxy-4-phenoxymethylpiperidine as an oil weighing 17.01 g (100% ).

IR (film) 5.91, 2.95 µM;

NMR (CDCl 3 ) α 1.46 (9H, s); 1.53-1.80 (4H, m) , 3.13-3.30 (2H, m) , 3.80 (2H, s) , 3.80-3.98 (2H, m) , 6, 84-6.99 (2H, m), 7.22-7.44 (3H, m);

Analysis for C17H25N04:

Calculated: C 66.42; H 8.20; N 4.56

Found: C 65.72; H 8.21; N 4.77.

A solution of 17.0 g (0.055 M) of N-t-butyloxycarbonyl-4-hydroxy-4-phenoxymethylpiperidine in 150 ml of methanol was saturated with HCl gas. After the mixture was cooled, it was again treated with HCl gas, and this procedure was repeated. After crystals had formed, the reaction mixture was treated with 500 ml of anhydrous ether and allowed to stir at room temperature overnight.

The product was filtered and washed with dry ether and dried under a stream of dry N2 to give 10.85 g (80.6%) of crystalline material, m.p. 202-204°C.

IR (KBr) 3.06, 3.14, 3.44, 3.57, 3.56, 6.33, 8.06 /mi;

NMR (D 2 O) a 2.00 (4H, broad s), 3.34 (4H, broad s), 4.00 (2H, s), 6.98-7.09 (3H, m), 7.30 -7.43 (2H, m).

Analysis for C12H17N02. HC1:

Calculated: C 59.13; H 7.44; N 5.75

Found: C 58.98; H 7.11; N 5.65

Claims (10)

1. Compound, characterized by the formula: and pharmaceutically acceptable salts thereof; wherein R x , R 2 and R 3 are each selected from the group consisting of hydrogen and alkyl of 1 to 6 carbon atoms; n is 1 or 2; and M and Q together form a divalent radical Z, where Z is selected from the group consisting of 2. Connection according to claim 1, characterized in that R 2 is hydrogen; R 3 is hydrogen or methyl; and M and Q form the radical Z, wherein Z is selected from the group consisting of 3. Connection according to claim 2, characterized in that n is 1, Rx is hydrogen and R3 is hydrogen. 4. Connection according to claim 2, characterized by the formula where n is 1. 5. Compound according to claim 2, characterized by the formula where n is 1- 6. Compound according to claim 4 or 5, characterized by atZer 7. Compound according to claim 4 or 5, characterized by atZer 8. Compound according to claim 4 or 5, characterized by atZer 9. Pharmaceutical preparation, characterized in that it contains a neuroprotective amount of a compound according to claim 1 and a pharmaceutically acceptable carrier. 10. Connection, characterized by the formula: where R2°9 R3 are each selected from the group consisting of hydrogen and alkyl of 1 to 6 carbon atoms; n is 1 or 2; and M and Q together form a divalent radical Z, where Z is selected from the group consisting of