FI68051B - PROCEDURE FOR THE PREPARATION OF THERAPEUTIC THERAPEUTIC ANVAENDBARA 3- (1H-TETRAZOLE-5-YL) -4H-PYRIMIDO (2,1-A) Isoquinolin-4-ONE - Google Patents

Description

1 68051

Process for the preparation of novel therapeutically useful 3- (1H-tetrazol-5-yl) -4H-pyrimido [2,1-a] isoquinolin-4-ones and pharmaceutically acceptable salts of these compounds

This invention relates to a process for the preparation of therapeutically useful 3- (1H-tetrazol-5-yl) pyrimido-10 [2,1-a] isoquinolin-4-ones having the following formula:

15 N N

S II "r2 \ ^ \ ....... ^

j 6 N5 3 | B

Wherein R is hydrogen, lower alkyl or lower alkenyl, and R 4 and R 4 are independently hydrogen or lower alkoxy, and for the preparation of pharmaceutically acceptable salts thereof.

2 68051

The substituent groups described above may be more specifically defined as follows: "lower alkyl" comprises straight and branched chain saturated aliphatic hydrocarbon groups having 1 to 6 carbon atoms, e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and For "butyl", tert-butyl, n-pentyl, isopentyl and n-hexyl, "lower alkenyl" comprises straight and branched chain unsaturated aliphatic hydrocarbon groups containing one double bond and having 2 to 6 carbon atoms, e.g. vinyl, allyl, isopropenyl, 2- or 3-methallyl and 3-butenyl, and "lower alkoxy" includes -C 1-4 alkoxy groups, e.g. methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec. .-butoxy, n-pentyloxy, isopentyloxy and n-hexyloxy.

The compounds of the invention have a tautomeric hydrogen atom and may thus exist in Forms I and I '. These forms may be present in greater or lesser amounts, and are in dynamic equilibrium with each other. For simplicity, Formula I has been selected to describe these compounds.

Il 3 68051

N N

j

N N

. XaJ "_> -V 'R4

10 R

a o Γ 1

XaJ ", χ R4 I 'a Formula I comprises both pyrimido [J, 1-§7-isoquinoline (double bond between carbon atoms 6 and 7) and the corresponding 6,7-dihydropyrimido? 2,1-§7-isoquinoline (single bond C-6 and C-7), as indicated by dashed line 2. The 6,7-dihydro derivatives of formula I in which R 30 is a substituent other than hydrogen contain an asymmetric carbon atom and in such cases the compounds may exist as optical isomers as well as racemates.

4 68051

The phrase "pharmaceutically acceptable salts" means non-toxic salts such as alkali metal salts, e.g. sodium and potassium salts, alkaline earth metal salts such as calcium, magnesium or barium salts, Aluminum-5 salts, ammonium salts and salts with organic bases, e.g. amines such as with triethylamine, n-propylamine, tri-n-butylamine, piperidine, ethanolamine, diethanolamine, triethanolamine, diethylaminomethylamine, ethylenediamine, Ν, Ν'-dibenzylethylenediamine, benz-10-ylamine, tris (hydroxymethyl) aminomethane The salt is formed by reacting a carboxylic acid or tetrazole of formula I with a substantially equimolar amount of a base in aqueous solution or in a suitable organic solvent such as methanol or ethanol, recovered in a manner known per se, such as by filtration if insoluble in the medium or by quenching or mixing with the addition of a non-solvent of the salt.

These new compounds can be prepared by the methods described below. Unless otherwise stated, the substituents R to R used in the description of the process have the same meaning as defined for the compounds of the formula I.

5 68051

Unsaturated pyrimido / 2,1-ajisoquinoline tetrasols of formula 5 _

Λ N

il

S

XAJ "

-V

15 R

can be readily prepared by a method of condensing a 1-aminoisoquinoline starting material of formula 20 R2 r3v ^ v \

Ti] n · r4 / γ nh2 with ethyl ethoxymethylene cyanoacetate in the presence or absence of an inert organic solvent (e.g. toluene) to give an acrylate intermediate of formula .... _ - TT -........

6 68051 I II v

HN

10 \ ιυ CH = C (C = N) CO 2 C 2 H 5 followed by reaction of intermediate V with aluminum azide in tetrahydrofuran to give tetrazole I "'ash.

The condensation step in the process described above can be carried out by reacting equimolar amounts of compound II 'and ethyl ethoxymethylene cyanoacetate. The reaction temperature may range from below room temperature (e.g., about 0 ° C) to an elevated temperature (e.g., 100 ° C or more). This gives the desired akx; ylate intermediate V and a cyclized imino ester / having the formula

NH

25 ^ Kyc02C2HS

I N T

'Vl 30!

K

a mixture which can be used as described above as an intermediate for the preparation of unsaturated pyrimido [2,1-a] isoquinoline-3-carboxylic acids of formula 1 '. The compounds of formula VI-68051 van VI have also been found to have potent antiallergic activity, as reported in Table II by the results of a rat PCA test for ethyl 4-imino-4H-pyrimido [2,1-a] isoquinoline-3-carboxylate.

The ratio of acrylate V to iminoester VI can be increased by performing the condensation step at lower temperatures, e.g. from room temperature to about 0 ° C.

Intermediate V is reacted according to the second step of the process with aluminum azide in tetrahydrofuran to give the desired tetrazole final product. Approximately equimolar amounts of the reaction components are used and the alumina can be conveniently prepared in situ by reacting sodium azide and aluminum chloride in molar ratios of about 3: 1. Although the reaction temperature is not critical, favorable results have been obtained at the reflux temperature of the solvent. The tetrazole product I "'can be easily recovered from the reaction mixture by adding sufficient water and then acidifying to effect precipitation. The tetrazole product prepared by this and the following method can be converted to a pharmaceutically acceptable cationic salt, if desired.

Tetrazole products of formula I "'may also be prepared by administering a nitrile intermediate of formula 25

R1 O

r * Jl JL

il 30 I VI1

| OF

35 8 68051 to react with aluminum azide in tetrahydrofuran. Approximately equimolar amounts of the reaction components are used and the alumina is preferably formed in situ from sodium azide and aluminum chloride in the same manner as described above for the tetrazole process (acrylate V). Reaction temperatures and tetrazole recovery have been described in connection with the acrylate conversion process.

The nitrile starting materials of the formulas VII and VII 'can be conveniently prepared from the 6,7-di-10-hydropyrimido / 2,1-a7isoquinoline esters of the formula I "by the following reaction scheme: R2Y ^ ^ rC ° 2' (alto" Pi, alkyl ") 2 ^ / γ «2 ('/ 1 liquid NH., S I —----- L. J closed container j steam bath iJL ss

k4 R

R4 VIII

I "dehydrating s 'agent, e.g. s ^ POC13 s'

O O

R2X / C = N 2 11

'll] R y ^^ vC5N

. Λ J

j

dehyflU: Qgenaatio. i! J

* 4 e.g. Pd (C) r p-cymene R A ^ VII VII · 9 68051

Amides of formula VIII are prepared by treating esters of formula I "with liquid ammonia, ammonium hydroxide or a solution of ammonia in a lower alkanol (e.g. methanol or ethanol) optionally containing sodium methoxide as a catalyst. The reaction is conveniently carried out in a closed vessel in a steam bath.

Amide intermediates can be converted to nitriles of formula VII using a dehydrating agent such as phosphorus pentoxide, thionyl chloride, a mixture of p-toluenesulfonyl chloride and pyridine, or most preferably phosphorus oxychloride. The dehydration is performed at an elevated temperature, most preferably under reflux conditions.

The nitrile VII can be converted to the corresponding unsaturated nitrile VII 'by dehydration at elevated temperature (a suitable dehydrating agent is described above for compounds I "and 1'). The preferred method involves heating the nitrile VII in the presence of palladium on carbon and p-cymene. described nitrile VII 'can be used as a starting material in the preparation of tetrazole I "'.

The compounds of formula I prepared by any of the methods described above may, if desired, be further reacted by methods known per se.

according to one or more substituents R, R

4

25 or R to convert other substituent groups of formula I.

within the scope of Thus, e.g., a lower alkoxy-substituted product can be converted to the corresponding hydroxy-substituted product using acid hydrolysis (e.g.

HCl or HCl-HOAc). This product can then in turn be realkylated, e.g. with an alkyl halide in the presence of a base, to give a lower alkoxy-substituted product, preferably one having a lower alkoxy substituent different from the starting material. Acylation of the hydroxy-substituted product with a benzoyl halide or lower alkanoyl halide gives the corresponding benzoyl or lower alkanoyloxy-substituted compound. Ozonolysis of the allyl-substituted product 10 68051 gives a formylmethyl-substituted compound which in turn can be reduced to the hydroxyethyl-substituted product. The allyl-substituted compound can also be hydrogenated to the corresponding hydroxypropyl product. Compounds having a dialkoxyethyl substituent can be prepared by treating the corresponding formylmethyl-substituted compound with a suitable lower alkanol, e.g. methanol gives dimethoxyethyl, ethanol gives dioxylethyl, etc.

The 1-aminoisoquinoline and 1-amino-3,4-dihydroisoquino-10 line starting materials used in the process described above are known or can be prepared by known methods.

One method for preparing 1-amino-3,4-dihydroisoquinolines is described in the following reaction scheme: 11 11 68051 3 ^ CrUC = N 1. CAK11N®CH (CH2) pLi®?

R / * 6 11 ^ 2 R3 CH-CSN

and hexane THF ^ r4 / ^ / 2- r2x 4 / ^ Ss / />

1 • L

LiAlHk or \ L1A1H ^ X. (CoH-) 50 R2 = H \ ^ Κ5> 2 ° i * '= \ 0 N. ΕΓ R2 i.cs2..m_ nh2] I ^ TxiiTococi, Δ i, 4 ^ V s 2 5 5- § (c2h5) 3obf4 or

^ CH ^ OSOgF

R2 „2 1 · m ~ y C2h- ° H., Δ κ3γ ^ \ ^ \ I να® -> I 1

2. NaOH

sr m2 5 6 Z = BF ^ tax SO ^ F ^ R = tax CH ^ n 68051

Alkylation of phenylacetonitriles 1 can be performed using various conventional bases such as sodium amide or sodium hydride, but almost quantitative yields have been obtained using the lithium salt of N-isopropylcyclohexylamine. The reduction of phenylacetonitriles (1 or 2) to form phenylethylamines IV and to obtain isothiocyanates 3 from the latter are known reactions. The cyclization of the isothiocyanates 3 to the isoquinolinium salts 5 takes place using very mild conditions, whereby 10 different substituents can be attached to the isoquinoline backbone. This general method is described in J. Chem. Soc., Perkin Trans. 1, 1, 33 (1976). Reaction of the isoquinolinium salts 5 in a steel vessel at about 100 ° C with ethanol saturated with ammonia gives either the fluoro-15 borate salt or the fluorosulfonate salt 6. Treatment of the salts with sodium hydroxide liberates the free base 6.

The 1-aminoisoquinoline starting materials can be prepared from the corresponding 1-amino-3,4-dihydroisoquinolines by dehydration, for example boiling in p-cymene in the presence of a carbon-palladium catalyst.

Using the Chichibabin reaction (J. Russ. Phys.

Chem. Soc., 50, 543 (1920) and U.S. Patent 3,847,919) also provide 1-aminoisoquinolines. Pesson and Richer ^ French. patent 3589M and Compt. rend., Ser. C., 262 (24), 25 1719 (1966) 7 describe the preparation of 1-aminoisoquinolines by reduction of the corresponding 1-hydrazino compounds.

The compounds of the invention or pharmaceutical compositions containing them may be administered to allergic human patients in oral unit doses of about 0.5 to 500 mg of active ingredient or orally in multiple doses, the total dose always being about 100 mg of active ingredient per day. When administered by inhalation or drip, lower doses are used, for example, only one-tenth of the normal oral dose. However, the above values are indicative only and the dose used will, of course, depend on the age and weight of the patient, the severity of the symptoms and the compound to be administered.

The following in vivo animal experiments show that the compounds of formula I are highly potent anti-allergic agents.

Assay for Biological Activity The assay is based on the Passive Skin Sensitization Assay (PCA), which is considered one of the best assays for use in determining the antiallergic activity of a test compound in humans. This method involves passive sensitization of skin sites in experimental animals with a reagin antibody and administration of the test drug and antigen after 24 hours. The allergic reaction is measured using Evans blue and evaluated as the spot diameter at the in-15 injection site. The details of the experiment are shown below.

Substances used in the experiment:

Ovalbumin (5 times crystallized) Dinitrobenzenesulphonic acid, Na + salt 9 20 Bordetella pertussis vaccine - phase I, 10 - 20 x 10 killed organisms / ml

Aluminum hydroxide gel - 10 mg / ml Potassium carbonate

Tris-buffered saline (TBS) - 0.02 mol / L 2-amino-2-25 hydroxymethyl-1,3-propanediol (Tris) and 0.15 mol / L NaCl; pH 8.2.

Preparation of antigen preparation - DNP-d EA

Ko. the ovalbumin antigen preparation is used as both an immunogen and an active antigen. The antigen-30 preparation is prepared as follows: 500 mg of ovalbumin (EA) and 500 mg are dissolved in 25 ml of distilled water and stirred at room temperature for 5 minutes. 500 mg of dinitrobenzenesulfonic acid, Na + salt (pre-recrystallized from 35 hot anhydrous ethanol) are then slowly added with stirring. The reaction mixture is then immediately placed in the dark and allowed to stand for 2 hours with stirring. After 2 hours, the mixture is placed in a suitable dialysis tube and dialyzed at 5 ° C using 5x4 liters of distilled water. After dialysis, the product is lyophilized and kept at room temperature in a rus-5 cup or amber container. The resulting antigen is a pale yellow amorphous solid which is highly soluble in water or saline. It is called DNP denatured ovalbumin (DNP-d EA).

Immunization Method for IgE Production 10 adult male Sprague-Dawley rats (weighing about 200 g) are used as a source of reagent-rich antiserum for the PCA assay. Immunization is performed with a combination of DNP-d EA on an Al (OH) ^ gel and B. pertussis vaccine. The preparation of the DNP-d EA gel is as follows: DNP-d EA is dissolved in TBS to give a concentration of 10 mg / ml. Slowly add 1 ml of this solution to 10 ml of Al (OH) gel (10 mg solids / ml) with constant stirring at room temperature. The mixture is mixed for an additional 30 minutes to ensure uniform adsorption of the antigen to the gel.

The gel thus obtained is used in combination with Phase I of B. pertussis vaccine to immunize male S / D rats as follows. Each rat is given 0.1 ml of DNP-d EA gel suspension intramuscularly on each hind leg (200 μg DNP-d EA, i.e. a total dose of 2 mg gel). Following these injections, 1.0 ml of B. pertussis vaccine (10 to 20 x 10 ') is administered intraperitoneally. Mild ether anesthesia is recommended during this treatment to ensure proper intravenous and intra-30 peritoneal injections. Nine days after immunization, animals are bled by cardiac puncture or abdominal aortic cannula during ether or pentobarbital anesthesia. Combined whole blood is allowed to clot, serum is separated by centrifugation, and single serum samples are stored refrigerated until IgE content is analyzed.

ti.

15 68051

Selection of High Titer Serum Samples Individual serum samples should be tested for reagent-antibody concentration before they can be combined with other sera, as all rats will not respond to the immunization treatment. A 1:50 salt dilution of serum from each immunized rat is used for this purpose. Subcutaneous injections of diluted sera (0.05 ml) are given into the backs of two small female sensitized rats (100-120 g) from which 10 hairs have been shaved. Different serum samples can be tested simultaneously in sensitized animals. After a latency period of 1-2 days, the antigenic effect is achieved by intravenous administration to each rat of 1 mg DNP-d EA in 0.5 ml of 0.5% Evans1 blue dye in saline. Sera showing positive PCA reactions at a dilution of 1:50, measured 20 to 30 minutes after antigen challenge, are pooled and divided into small even aliquots and kept at -70 ° C or below until use. Negative sera may be discarded.

The IgE titer of the pooled antisera can then be determined. Multiple two-fold dilutions (1: 5 to 1: 160) of unheated sera and sera heated at 56 ° C for 1 hour are prepared and 0.05 ml of each dilution is injected subcutaneously into the backs of 25 sensitized female rats. At least 4 animals must be used for both heated and unheated serum titrations. After a daily latency period, each group is given 1 mg of DNP-d EA in 0.5 ml of 0.5% Evans1 in blue. Reactions are read by reflecting the skin 20 to 30 minutes after dosing. The intensity (bluing) and the diameter of the spot are measured and recorded. The titre is defined as the reciprocal of the highest dilution of unheated serum that results in a measurable PCA reaction (> 6 mm in diameter) in at least half of the number of sensitized animals. Antisera with a titer of 50 or higher are approved for PCA testing.

ie 68051 These antisera are sterile-filtered and kept at -70 ° C or below until use. Alternatively, lyophilization in small amounts may be used.

PCA test method 5 1. Young females are used as experimental animals

Sprague-Dawley rats (90-110 g). Rats are conditioned (adapted to conditions) for at least 5 days prior to use by feeding and water without restriction.

2. Passive sensitization. The experimental animals are prepared for passive sensitization by carefully shaving the hairs off each side of the back with a fine toothed cutter. Use a 27-gauge 11.9 mm needle mounted in a 1 ml tuberculin syringe to inject subcutaneous dilutions of antiserum. 4 dilutions of antiserum for 15 min (2 on each side) are used. The exact dilutions used depend on the antiserum titer. For example, if the antiserum titer is 50 then dilutions of 1:10, 1:20, 1:30, 1:40 are used; if the titer is 100 then dilutions of 1:20, 1:40, 1:60 and 1:80 are used. The order of each dilution 20 is used either clockwise or counterclockwise to facilitate readings. The latency period is at least 1 day, but not more than 2 days.

3. Each test compound is administered to 4 test animals. Disodium cromoglycate (DSCG) dissolved in saline is administered intravenously (i, v.) At the time of antigen action. Test compounds are dissolved in sodium bicarbonate solution whenever possible. Compounds insoluble in bicarbonate solution are suspended in Tween / CMC.

Test compounds are administered i.v. or orally 30 either 1-5 or 10 minutes before antigen action.

4. Antigen effect and reaction evaluation.

The PCA reaction is accomplished by intravenous administration of 1 mg DNP-d EA in 0.5 ml of 0.5% Evans blue saline to each experimental animal. PCA reactions 35 are maximal 20 to 30 minutes after dosing. Reactions are visually labeled based on color intensity and mean diameter of the 68051 spots at each antiserum dilution. Both measurements are made by reflection on a surface. For comparison purposes, the number of control groups (untreated) must be at least 5% and usually 10% of the total number of animals tested on each day.

The inhibitory potency of the investigational drug is expressed as a% reduction in effective antiserum titer in the treated group compared to the control group.

10 Results

The test results of a sample representative of the compounds tested are shown in Tables I and II together with the values of disodium cromoglycate (DSCG). DSCG is administered at the time of antigen action. The results are reported with an ID_ value of 15 na, i.e. at a dose of the compound that inhibits 50% of the reaction.

18 68051

Table I

Formula of test compound:

N N

O,

r2 Ϊ Jl I

I H

r ^ T ^ ^ R3 R4

Example R ° tta 'pCA test 234 ΙΟςη' m9 / k? n: o R R R u p.o.

2 C-H, H H 0.10

Δ D

The 1 H OCH 3 OCH 3 ^ 0.030 DSCG >> 30 DSCG ID ^ dose is 0.6 mg / kg (i.v.) 19 68051

Table II

Formula of the test compound: __ R4

Example PCA Experiment 2 34 ID 50 'm 9 / k 9 No. R R R.

i.v. po

1 H H H 0.04 4 C 2 H 5 H H 0.009 0.04 DSCG 0.6 >> 30 20 68051

The preparation of starting materials and final products is described below. All temperatures are in degrees Celsius. Melting and boiling points are uncorrected. "Skellysolve B" is a petroleum ether fraction, b.p. 60-68 ° C, using substantially n-hexane, manufactured by Skelly Oil Co. Preparation of starting materials A. 1-Amino-3,4-dihydroisoquinolines a) Phenylacetonitriles (structure 2) 1. (-) - 2-allyl-2- (4-methoxyphenyl) acetonitrile 10 n-butyllithium (0.16 mol, 1, 6-M in hexane) was added under nitrogen to dry tetrahydrofuran (100 mL) cooled in a C 3 -C 4 acetone bath. Solutions of N-isopropylcyclohexylamine (22.6 g, 0.160 mol) and p-15 methoxyphenylacetonitrile (21.2 g, 0.144 mol) in tetrahydrofuran (10 ml each) were then added dropwise over 10 minutes. The mixture was stirred in the cold for 10 minutes while allyl bromide (24.2 g, 0.20 mol) was added dropwise over 10 minutes. Stirring was continued in the cold for 15 minutes and then at ambient temperature for 1.5 hours. The solution was diluted with diethyl ether and washed successively with 4% hydrochloric acid (2 x 100 mL), water and brine. The ether solution was dried (Na 2 SO 4), concentrated and the residue was distilled to give 24.2 g (89% yield) of nitrile, b.p. 99-114 ° (0.1 mm).

2. (-) - 2-Phenylbutyronitrile Using Method A a) 1, alkylation of phenylacetonitrile with ethyl bromide gave the title compound in 98% yield, b.p. 110-116 ° / 13 Torr. (According to Compt. Rend., 232, 1424 (1951) bp 124-126 ° / 25 Torr).

B) Phenethylamines (structure 4) 1. (-) - 2-allyl-2- (4-methoxyphenyl) ethylamine (-) - 2-allyl-2- (4-methoxyphenyl) acetonitrile (159-7 g, 0.852 mol) ) in diethyl ether (200 mL) was added dropwise over 20 minutes to a stirred slowly refluxed mixture of lithium aluminum-35 hydride (LiAlH 2, 42.2 g, 1.11 mol) in diethyl ether (Θ00 mL). The mixture was heated to reflux for an additional 1.25 hours 11.

21,68051 and then cooled in an ice-water bath. Excess LiAlH 2 was decomposed by the slow dropwise addition of water until gas evolution ceased and a white precipitate formed. The mixture was filtered and the filter cake was washed with good diethyl ether. Concentration of the filtrate gave the title product (146 g, 90%) as a cloudy oil.

A portion of the oil was distilled to give pure product, b.p. 78-84 ° (0.1 Torr); the hydrogen fumarate salt melted at 137-139 ° after recrystallization from ethanol / et-10.

Anal. Calcd for 2 H-NO 2, CH 2 Cl 2: C, 62.52; H 5.88; N 4.56.

Found; C 62.05; H 7.22; N 4.50.

2. 2- (4-methoxyphenyl) ethylamine and (-) - 2-phenyl-15-butylamine

In the same manner as described above for the preparation of (-) - 2-allyl-2- (4-methoxyphenyl) ethylamine, p-methoxyphenylacetonitrile and (-) - 2-phenylbutyronitrile were reduced with lithium aluminum hydride 2- (4-methoxyphenyl) -20 ethylamine / Ber. , 42, 4778 (1909), 7 and t-) -2-phenylbutylamine ^ Compt. rend., 184, 30 (1927) 7.

c) Arylalkyl isotlocyanates (structure 3) Starting from the appropriate arylalkylamines, the method described by Gittos et al., 25 / J. Chem. Soc. , Perkin Trans., 1, 1, 33 (1976) ^ 7, to synthesize the following isothiocyanates: 2- (4-methoxyphenyl) ethyl isothiocyanate (100% yield), b.p. 112-114 ° / 0.1 Torr. (U.S. Patent 3,895,014 bp 119-120 ° / 0.5 Torr.); 2- (3-methoxyphenyl) ethyl isothiocyanate (89% yield), b.p.

30 135 - 140 ° / 0.1 Torr; 2- (3,4-dimethoxyphenyl) ethyl isothiocyanate (52% yield, b.p. 155-165 ° / 0.4 Torr. (Literature b.p. 138-140 ° / 0.2 Torr)) (-) - 2-phenylbutyl isothiocyanate (97% yield), bp 85-98 ° / 0.1 Torr, and (-) - 2-allyl-2- (4-methoxyphenyl) ethyl isothiocyanate 35 (81% yield), mp 136-144 ° / 0.1 Torr.

d) 1-Ethylthio and 1-methylthioisoquinolinium salts (Structure 5) The methods described by Gittos 22,68051 (U.S. Patent 3,895,014) and Gittos et al. / J. Chem. Soc.

Perkin Trans. 1, 1, 33 (1976) -7, for the cyclization of the above isothiocyanates to the following isoquinolinium salts: 1-ethylthio-3,4-dihydro-6,7-dimethoxyisoquinolinium-5-fluoroborate (79% yield), m.p. . 175-177 ° C from ethanol / ether (literature reported mp 174-176 ° C); 3,4-dihydro-7-methoxy-1-methylthioisoquinolinium fluorosulfonate (41% yield), m.p. 208-209.5 ° C from acetonitrile.

Anal, calculated for C 12 H 13 NOS.HSO 2 F 10 C 42.99 H 4.59 N 4.56 S 20.86 Found: C 43.41 H 4.93 N 4.53 S 20.99 3, 4-dihydro-6-methoxy-1-methylthioisoquinolinium fluorosulfonate (100% crude yield), m.p. 106-119 ° C from methylene chloride / ether; (i) -4-ethyl-3,4-dihydro-1-methylthioisoquinoline-15-fluorosulfonate and (±) -4-allyl-3,4-dihydro-7-methoxy-1-methylthioisoquinolinium fluorosulfonate isolated as gummy oils which were used without purification.

e) 1-Amino-3,4-dihydroisoquinolines (Structure 6) 3,4-Dihydro-7-methoxy-1-methylthioisoquinolinium fluorosulfonate (10.0 g, 0.0362 mol) was added to ethanol (100 ml). , which was impregnated with ammonia in a steel tube. The stirred mixture was heated on a steam bath for 2 hours. The mixture was combined with the material from four similar preparations and evaporated to dryness. The residue was partitioned between 5N sodium hydroxide (300 ml) and methylene chloride. The organic layer was washed with water (2x) and dried over sodium sulfate. The solid obtained after removal of methylene chloride was recrystallized from benzene to give 23 g (72% yield) of 1-amino-3,4-dihydro-7-methoxyisoquinoline, m.p. 114-117.5 ° C. Recrystallization from ethyl acetate gave an analytical sample, m.p. 117.5-119.5 ° C.

Anal Calcd for C 68.16 H 6.86 N 15.90 Found: C 68.01 H 6.81 N 15.83 11.

23 68051

The following 1-amino-3,4-dihydroisoquinolines were prepared in a similar manner: 1-amino-3,4-dihydro-6,7-dimethoxyisoquinoline ^ akugaku Zasshi, 82, 352 (1962) J7 (105% crude yield, fluoroborate salt melted at 181-185 ° C after crystallization from ethanol); 1-amino-3,4-dihydro-6-methoxy-isoquinoline (41% s-administration), m.p. 129-131 ° C from ethyl acetate.

Anal Calcd for C 24 H 19 N 2 O C 68.16 H 6.86 N 15.90 Found: C 68.39 H 7.01 N 16.05 (*) -1-amino-4-ethyl-3, 4-dihydroisoquinoline (102% crude brown oil), characterized as the monohydrogen fumarate salt, m.p. 146-148 ° C from water.

Anal Calcd for C 12 H 14 N 2 • C 4 H 4 O 4 C 62.05 H 6.25 N 9.65 Found: C 60.95 H 6.12 N 9.26 and (i) -4-allyl-1- amino-3,4-dihydro-7-methoxyisoquinoline, a brown oil which, after isolation and converted to the monohydrogen fumarate salt, melted at 174-176 ° C after crystallization from ethanol.

Anal, calculated for g ^ OC ^ H ^ O ^ C 61.43 H 6.07 N 8.43 found: C 60.82 H 6.15 N 7.82 B. 1-aminoisoquinolines 25 1. 1-amino- 4-methoxy-isoquinoline

Upon reduction of 1-hydrazino-4-methoxyisoquinoline with hydrogen and Raney nickel in ethanol according to the method described by Pesson and Richer in Compt. rend., Ser. C, 262 (24), 1719 (1966), a 17% yield of the title compound was obtained, m.p. After chromatography at 112.5-114 ° C on alumina with chloroform / ethanol (20: 1).

2. A mixture of 1-amino-4-ethylisoquinoline (-) - 1-amino-4-ethyl-3,4-dihydroisoquinoline (6.83 g) and 10% palladium on carbon (1.5 g) 35 mixtures of β-cymene (80 ml) were heated at reflux for 4 hours. The mixture was filtered and the filtrate evaporated to dryness in vacuo to leave an oil which was crystallized successively from Skellysolve B and cyclohexane to give 1.84 g (27% yield) of product, m.p. 84-85 ° C. Anal Calcd for C 11 H 12 N 2 C 76.71 H 7.02 N 16.27 Found: C 76.87 H 6.92 N 16.15

Example 1 3- (1H-Tetrazol-5-yl) -4H-pyrimido [2,1-a] isoquinol-4-one (via Intermediate V) A. Ethyl 2-cyano-3- (isocolinylamino) acrylate 10-aminoisoquinoline A mixture of (14.4 g, 0.10 mol) and ethyl ethoxymethylene cyanoacetate (16.9 g, 0.10 mol) was immersed in an oil bath at 105-110 ° C and kept under nitrogen for 10 minutes. During this time, the mixture melted, ethanol evolved, and solidified. It was crystallized from toluene to give bright yellow crystals (18 g, 67% yield) of ethyl 4-imino-4H-pyrimido [2,1-a] isoquinoline-3-carboxylate, m.p. 197-199 ° C. Recrystallization from toluene gave an analytical sample, m.p. 199-201 ° C.

The first toluene mother liquor was concentrated to a volume of about 150 mL by boiling and then diluted with Skellysolve B (100 mL). The mixture was filtered and the filtrate dried to leave a yellow substance which was crystallized from methanol to give 5.5 g of ethyl 2-cyano-3-25 (isoquinolylamino) acrylate, m.p. 129-133 ° C. Add this material (1.7 g, 27% overall yield), m.p. 129-131 ° C, was obtained by concentrating the ethanol-mother liquor. Chromatography of the latter yield using silica (60 g) and chloroform followed by recrystallization from methanol-30 gave an analytical sample, m.p. 129-130 ° C.

Anal, calculated for C 67.40 H 4.90 N 15.72 found; C 67.10 H 5.01 N 15.78 Il 25 6 8 0 51 B. 3- (1H-Tetrazol-5-yl) -4H-pyrimido [2,1-a] isoquinol-4-one

Aluminum chloride (2.98 g, 0.0224 moles) was added to carefully stirred cooled (ice / water) tetrahydrofuran (150 mL). Sodium azide (4.36 g, 0.0672 mol) was then added and the resulting mixture was heated to reflux for 0.5 hours to complete the formation of aluminum azide.

To the cooled mixture was added ethyl 2-cyano-3-10 (isoquinolylamino) acrylate (4.93 g, 0.0184 mol). The resulting mixture was heated at reflux for 20 hours, evaporated to dryness and diluted with water (200 ml). The aqueous mixture was acidified with 37% hydrochloric acid (20 mL). Substance, m.p. 260-290 ° C (decomposed), collected and mixed with 150 ml of warm 2% KHCO 3 and water.

The mixture was washed with diethyl ether, and the water-insoluble matter was removed from the aqueous layer by filtration. The filtrate was acidified with acetic acid to precipitate tetrazole, m.p.

304-308 ° C (decomposed). Recrystallization from N, N-dimethyl-20-formamide gave pale yellow needles: 1.1 g (22.6% yield), m.p. 313-314 ° C (decomposed).

Anal, calculated for C 12 H 9 N 9 O 2

C 59.09 H 3.05 N 31.81 found: C 58.70 H 3.02 N 31.41 Example 2 (1) -7-ethyl-6,7-dihydro-3- (1H-tetrazole- 5-yl) -4H-pyrimido [2,1-a] isoquinol-4-one (via nitrile VII A. (1) -7-ethyl-6,7-dihydro-4-oxo-4H-pyrimido [2,1-a] ~ isoquinoline-3-carboxamide 30 (i) -7-ethyl-6,7-dihydro-4-oxo-4H-pyrimido [2,1-a] isoquinoline-3-carboxylate (1.0 g) and liquid ammonia ( 25 ml) of the mixture in a steel vessel was heated on a steam bath for 1.5 hours, removing ammonia to leave amidine, flake-like crystals 900 mg (100% yield), m.p.

35 197-202 ° C. Recrystallization from methanol gave colorless crystals, m.p. 205-207 ° C.

26 68051

Anal Calcd for C 66.90 H 5.61 N 15.61 Found: C 66.37 H 5.31 N 15.42 B. (1) -7-ethyl-6,7-dihydro-4-oxo- 4H-pyrimido-5H-isoquinoline-3-carbonitrile (±) -7-ethyl-6,7-dihydro-4-oxo-4H-pyrimido, [2,1-a] isoquinoline-3-carboxamide (800 mg ) and phosphorus oxychloride (8 ml) was heated at reflux for 2 hours. The mixture was evaporated to dryness and the residue partitioned between methylene chloride and potassium carbonate. The organic layer was dried over sodium sulfate and evaporated to dryness to leave 600 mg (80% yield) of nitrile, m.p. 145-148 ° C. Recrystallization from methanol gave yellow crystals, m.p. 153-154 ° C.

Anal, calculated for C 71.69 H 5.21 N 16.72 found: C 71.31 H 5.11 N 16.75 C. (i) -7-ethyl-6,7-dihydro-3- ( 1H-tetrazol-5-yl) -4H-pyrimido [2,1-a] isoquinol-4-one 20 (1) -7-ethyl-6,7-dihydro-4-oxo-4H-pyrimido [2,1-a] isoquinoline A mixture of 3-carbonitrile (208 g, 0.836 mol), sodium azide (59.8 mg, 0.92 mmol) and ammonium chloride (49.1 mg, 0.92 mmol) in N, N-dimethylformamide (2 mL) was stirred. 19 hours in an oil bath temperature at 120 ° C.

The mixture was diluted with water and acidified with dilute hydrochloric acid to give 215 mg (87% yield) of tetrazole, m.p. 254-258 ° C (dec.). Recrystallization from acetic acid gave pale yellow crystals of an analytical sample, m.p. 282-283.5 ° C (dec.).

Anal, calculated for C 18 H 19 N 2 O 2

C 61.21 H 4.79 N 28.56 Found: C 61.44 H 4.81 N 28.66 il 68051 27

Example 3 6,7-Dihydro-9,10-dimethoxy-3 (1H-tetrazol-5-yl) -

4H-pyrimido [2,1-a] isoquinol-4-one (nitrile VII

via 5 A. 6,7-Dihydro-9,10-dimethoxy-4-oxo-4H-pyrimido-12,1-a7isoquinoline-3-carboxamide

As described in Example 2A, ethyl 6,7-dihydro-9,10-dimethoxy-4-oxo-4H-pyrimido [2 ", 1-isoisoquinoline-3-carboxylate was converted to the amide in 92% yield, m.p.

10,313-315 ° C from 2-methoxyethanol.

Anal, calculated for 5H ·) 5 ^ 3 ^ 4 C 59.79 H 5.02 N 13.95 found: C 59.62 H 5.09 N 13.94 B. 6,7-dihydro-9,10- Dimethoxy-4-oxo-4H-pyrimido-15 [3,1-a] isoquinoline-3-carbonitrile

In the same manner as in Example 2B, 6,7-dihydro-9,10-dimethoxy-4-oxo-4H-pyrimido (2,1-a] isoquinoline-3-carboxamide was dehydrated to the nitrile in 93% yield, mp 261-262 ° C from acetic acid. .

Anal, calculated for C 63.59 H 4.63 N 14.83 found: C 63.47 H 4.82 N 14.79 C. 6,7-dihydro-9,10-dimethoxy-3- (1H- tetrazol-5-yl) -4H-pyrimido [2,1-a] isoquinol-4-one In accordance with Example 2C, 6,7-dihydro-9,10-dimethoxy-4-oxo-4H-pyrimido [2 *, The 3-carbonitrile was converted to the corresponding tetrazole in 57% yield, m.p. 286-288 ° C (decomposed) from acetic acid.

Anal Calcd for C 55.21 H 4.32 N 25.76 Found C 54.89 H 4.39 N 25.64 28 68051

Example 4 7-Ethyl-3- (1H-tetrazol-5-yl) -4H-pyrrolido [R, 1- & 7-isoquinol-4-one] (via nitrile VII1) A. 7-Ethyl-4-oxo-4H- Pyrimido [2,1-d] isoquinoline-5,3-carbonitrile (1) -7-ethyl-6,7-dihydro-4-oxo-4H-pyrimido [2,1-a] isoquinoline-3-carbonitrile (3.5 g) and a stirred mixture of 10% palladium on carbon (1.5 g) in β-cymene (50 ml) was heated at reflux for 18 hours. Mixture 10 was diluted with methylene chloride and filtered to remove the catalyst. The solvents were removed on a rotary evaporator and the residue was crystallized from ethanol to give 1.6 g (46% yield) of the title compound, m.p. 208-211 ° C. Crystallization from toluene and ethanol sequentially gave an analytical sample, m.p. 218-219 ° C.

Anal, calculated for C

C 72.27 H 4.45 N 16.86 found: C 72.00 H 4.65 N 16.56 B. 7-ethyl-3- (1H-tetrazol-5-yl) -4H-pyrimido-20 [ 2.1 ~ € isoquinolin-4-one

Aluminum chloride (595 mg, 4.46 mmol) was added to stirred ice-cold tetrahydrofuran (40 mL). Sodium azide (870 mg, 13.4 mmol) was then added and the mixture was heated to reflux for 0.5 h to complete the formation of Aluminum-25 azide.

7-Ethyl-4-oxo-4H-pyrimido [2,1-a] isoquinoline-3-carbonitrile (1.0 g, 4.05 mmol) was added and the mixture was heated at reflux for 18 hours. The mixture was diluted with water and acidified with 37% hydrochloric acid to precipitate tetrazole. The crude tetrazole was heated with 5% sodium carbonate / aqueous solution. The aqueous mixture was washed with ethyl acetate and the aqueous layer was heated with decolorizing carbon and filtered. Upon acidification of the filtrate with acetic acid, 1.0 g (85% yield) of product precipitated, m.p. 301 35-303 ° C (decomposed). Crystallization from 2-methoxyethanol gave pale yellow needles, m.p. 310.5-312 ° C (decomposed).

tl 68051 29

Anal Calcd for C 61.63 H 4.14 N 28.76 Found: C 60.99 H 4.07 N 28.28

Example 5 The tetrazole products of Examples 1 to 6 are converted to the corresponding sodium, potassium, ammonium, calcium, magnesium, barium, aluminum, triethylamine, n-propylamine, tri-n-butylamine, piperidine, ethanolamine, diethanolamine, triethanolamine, diethylamino-10-ethylamine, ethylenediamine, pyrrolidine, benzylamine, tris (hydroxymethyl) aminomethane and Ν, Ν'-di-benzylethylenediamine salts by giving them react with an equivalent of the appropriate metal hydroxide, ammonium hydroxide or amine in water or ethanol and then filter the salt if it is insoluble or evaporate the solvent if the salt is soluble therein.

Claims (7)

A process for the preparation of therapeutically useful 3- (1H-tetrazol-5-yl) -4H-pyrimido [2,1-a] isoquinolin-4-ones of the formula n N N 2. ii II R II H n 10 1. J 8 9 11 15 r 3 ^ R 4 20 2 wherein R is hydrogen, lower alkyl or lower alkenyl and 3.4 R 3a R independently of one another are hydrogen or lower alkoxy, and for the preparation of pharmaceutically acceptable salts of these compounds, characterized in that tl 31 68051 a) 1-aminoisoquinoline starting material of formula R2 5 II 'R4 NH2 is condensed with ethyl ethoxymethylene cyanoacetate, optionally in the presence of an inert organic solvent, and the resulting acrylate intermediate of formula R2 20 V HN \ CH = C (C = N} CO2C2H5 25 is reacted with aluminum azide in tetrahydrofuran to give a tetrazole of the formula Λ NS y, v R4 32 6 8 0 51 • · k 2 3, in which R, R 4 and R have the same meaning as above »or b) a nitrile of formula 50 O VII VII 'R 15 is reacted with aluminum azide in the presence of tetrahydrofuran. * * 1H-tetrazol-5-yl) -4H-pyrimido [2,1-a] isoquinolin-5-yl-4-one formulation 10 NN S II II r2 ^ / N ή 6 N5 H τ I 11 R3 / y 20 R4 2 3 color R is an alcohol, an alkyl or a alkenyl, and R 4 and R are used as an ingredient or an alkoxy, the same as a pharmaceutical product having the same alkoxy, 25 turns of which are derived, (a) 1-aminoisoquinoline with formula 34 68051 R2 s II κ, / γγΝ 10 r4 NH2 condenser with ethyl ethoxymethylencyanoacetate, optionally with the aid of inert organic solvents, and with acrylate-breast products of formula 15 R2 20 X. r3 y] p4 HN R \ CH = C (C = N) CO2C2H5 25 in the case of aluminum azide and tetrahydrofuran for the tetrazole formulation R1 O f | \\ I I "'ΑΛ»; 35 f R3 "y ^ R4