NO134113B - - Google Patents

Description

The present invention relates to a process for the production of new 1-phthalazone derivatives with the general formula

where R means a hydrogen atom or a lower alkyl group, means a hydrogen atom, a lower alkyl group, a lower alkylsulfonyl group, or phenyl or tolyl or a phenyl group of the general formula

where R^ means a hydrogen or a halogen atom, a lower alkyl or lower alkoxy group,

R,, means a hydrogen or halogen atom, a lower alkyl, lower alkoxy or lower alkoxycarbonyl group, 1*2 means a hydrogen or halogen atom, a lower

alkyl or lower alkoxy group,

R^ means a hydrogen or halogen atom, a lower

alkyl-, lower alkoxy-, lower alkoxycarbonyl-, amino

or acetamido group under the condition that R, R , R 2 and R 2 do not mean a hydrogen atom at the same time.

fSt»- The above compounds can be prepared using one of the KlWW^W}^..,;..,.

: the following processes:

a) A compound, with the general formula

where? R. ,: R'^' and R_ have, the same meaning as in formula j", Yi means an alkoxycarbonyl group or a halogen>:arbo-•V is reacted' with an alkali metal borohydride in the presence

• ; or absence of a metal halide.

\ b) A compound with the general formula

where R, R^ and R^ have the meanings indicated in formula (I), is reacted with a hydrazine derivative of the formula where R^ has the same meaning as indicated in formula (I), with the exception of an aryl group. c) A compound with the general formula

where R^, R2 and R^ have the same meanings as in formula

(I), and where

Z means an alkoxycarbonyl group, an aldehyde or a

acyl group,

is reacted with a Grignard compound of formula

where R has the same meanings as stated in formula (I), with the exception of a hydrogen atom, and where

X means a halogen atom, and,

if desired, each of the reaction products from (a), (b) and (c) above is allowed to react with an acid.

Compounds according to the present invention can be produced by one of the processes described above. These manufactured compounds are new. In experimental atherosclerosis, which is induced by cholesterol feeding, the aforementioned compounds showed a very good effect with respect to preventing atherosclerosis by inhibiting cholesterol deposition on the arterial wall. They also prevent the increase in coagulation ability and susceptibility to thrombosis, which is induced by injecting animals with cholesterol or adrenaline. That is to say, they prevent a shortening of the clotting time for blood as well as an increase in adenosine diphosphate-induced platelet aggregation in animals. The compounds according to the present invention are useful in the treatment of atherosclerosis and thrombotic diseases, such as cerebral thrombosis, coronary thrombosis, peripheral thrombosis, cerebral atherosclerosis, coronary atherosclerosis, arteriosclerosis obliterans, thromboangitis obliterans, thrombophlebitis, angiopathy of diabetes mellitus and nephropathy of diabetes mellitus.

The starting compounds, which are used according to the present invention, and which are expressed by means of formulas (II) and (III), can be prepared by means of analogous methods known in the field, or by means of new methods described below. 1) Compounds of formula (II) can be prepared using known methods [e.g. J. of Am. Chem. Soc, 68, 1316 (1946)] of naphthalene derivs. Examples of the compounds include 4-ethoxycarbonyl-2-phenyl-1-phthalazone, 4-methoxycarbonyl-2-methyl-1-phthalazone, 4-ethoxycarbonyl-2-methanesulfonyl-1-phthalazone, 4-methoxycarbonyl-2-benzenesulfonyl-1- phthalazone, 4-ethoxycarbonyl-2-toluenesulfonyl-l-phthalazone, 4-ethoxycarbonyl-2-tolyl-1-phthalazone, 4-methoxycarbonyl 1-2-(p-methoxyphenyl)-1-phthalazone-, 4-ethoxycarbonyl-2- (p-chlorophenyl)-1-phthalazone, 4-ethoxycarbonyl-2-(p-bromophenyl)-1-phthalazone, 4-ethoxycarbonyl-2-(p-ethoxycarbonyl-phenyl)-1-phthalazone, and 4-chlorocarbonyl- 2-phenyl-l-phthalazone.

Furthermore, 4-Alkoxycarbonyl or 4-chlorocarbonyl-1-phthalazone derivatives, which have one or more substituents, such as a chlorine atom, bromine atom, alkyl, alkoxy, aminoacetylamino and alkoxycarbonyl group- in one of C-5, C- 6, the C-7 and C-13 positions of the phthalazone core. As examples can be mentioned. 7-chloro-4-ethoxycarbonyl-l-phthalazone, 7-bromo-4-methoxycarbonyl-l-phthalazone, 4-ethoxycarbonyl-7-methoxy-l-phthalazone, 4-ethoxycarbonyl-7-methoxy-2-phenyl-l- phthalazoner 5-acetylamino-4-ethoxycarbonyl-l_phthalazone, 8-acetylamino-4-ethoxycarbonyl-7-methoxy-l-phthalazone, 8-amino-7-chloro-4-ethoxycarbonyl-l-phthalazone, 6,7-dimethyl-4 -ethoxycarbonyl 1-1.-phthalazone, 4-methoxycarbonyl-2,6,7-trimethyl-l-phthalazone, 2-benzenesulfonyl-4-ethoxycarbonyl-7-methoxy-l-phthalazone and 7-bromo-4-ethoxycarbonyl-2 -(p-toluenesulfonyl)-1-phthalazone.

2) The compounds of formula (III) can be prepared using the following reaction schemes.

The author of Ber. 40, 72 (1907) and Annual Report of Department of Pharmacy, Kanazawa University (Japan), Vol. 12, 1 - 6

(1961) claim that they have obtained methylene phthalide or o-oi-hydroxy-acetylbenzoic acid by hydrolysis of o-cu-bromoacetyl-benzoic acid. We have found it to be 4-oxo-3,4-dihydroisocoumarin. The compounds of formula (III), which have an alkyl substituent in the 3-position, can be prepared by alkylation of 4-oxo-3,4-dihydro isocoumarin. Examples of compounds of formula (III) include 4-oxo-3,4-dihydroisocoumarin, 3-methyl-4-oxo-3,4-dihydroisocoumarin, 3,3-dimethyl-4-oxo-3,4-dihydroisocoumarin, and their derivatives which. has one or two substituent ethers, such as a chlorine atom or a bromine atom, an alkyl, alkoxy, amino, acetylamino and alkoxycarbonyl group in one of C-5-, C-6-, C-7-

and the C-8 residues in the dihydroisocoumarin core.

According to the embodiment of method a), the compound (II) is brought into reaction with an equimolar amount or an excess, and then preferably between 1.5 and 10 mol per

mole of compound (II), of alkali metal borohydride, such as sodium borohydride, potassium borohydride or lithium borohydride. The reaction is preferably carried out in the presence of metal halides, such as calcium chloride, magnesium bromide, lithium chloride, lithium bromide or lithium iodide. Sodium trimethoxyborohydrides can also be used. When the compound of formula (II) is 4-Alkoxycarbonyl-1-phthalazone derivative, i.e. that Y in formula (XI)

means an alkoxycarbonyl group, lower aliphatic alcohols, such as methanol, ethanol or propanol, it can preferably be used as a solvent, and the reaction is preferably carried out at a temperature between 0° and 150°C, and then especially between 0 and 100°C. When the compound of formula (II) means 4-chlorocarbonyl-1-phthalazone derivative, i.e. when Y in formula (II) means a chlorocarbonyl group, a solvent such as dioxane, tetrahydrofuran or benzene can preferably be used, and the reaction is preferably carried out at a temperature between 0 and 100°C, and then preferably between 0 and 50°C .

According to the embodiment of method b), a compound of formula (III) is brought into reaction with an equimolar amount or excess [preferably 1. - 10 mol per mol of compound (III)] of a hydrazine derivative of formula (IV). Examples of the hydrazine derivative include hydrazine, methylhydrazine, methanesulfonylhydrazine, benzenesulfonylhydrazine and p-toluenesulfonylhydrazine. Although the reaction can be carried out in the absence of a solvent, the reaction is preferably carried out in the presence of a solvent, such as water, lower aliphatic alcohols, e.g. methanol, ethanol or propanol, and at a temperature between 0 and 150°C, preferably between 50 and 100°C. trimethyl-l-phthalazone, 2-benzenesulfony1-4-ethoxycarbonyl-7-methoxy-l-phthalazone and. 7-Bromo-4-ethoxycarbonyl-2-(p-toluenesulfonyl)-1-phthalazone.

2) The compounds of formula (III) can be prepared using the following reaction schemes.

The author of Ber. 40, 72 (1907) and Annual Report of Department of Pharmacy, Kanazawa University (Japan), Vol. 12, 1 - 6

(1961) claim that they have obtained methylenephthalide or o-ui-hydroxyacetylbenzoic acid by hydrolysis of o-tu-bromoacetylbenzoic acid. We have found it to be 4-oxo-3,4-dihydroisocoumarin. The compounds of formula (III), which have an alkyl substituent in the 3-position, can be prepared by alkylation of 4-oxo-3,4-dihydro isocoumarin. Examples of compounds of formula (III) include 4-oxo-3,4-dihydroisocoumarin, 3-methyl-4-oxo-3,4-dihydroisocoumarin, 3,3-dimethyl-4-oxo-3,4-dihydroisocoumarin, and their derivatives which. has one or two substituent ethers, such as a chlorine atom or a bromine atom, an alkyl, alkoxy, amlno, acetylamino and alkoxycarbonyl group in one of C-5-, C-6-, C-7-

and the C-8 positions of the dihydroisocoumarin core.

According to the embodiment of method a), the compound (II) is reacted with an equimolar amount or an excess, and then preferably between 1.5 and 10 mol per

mole of compound (II), of alkali metal borohydride, such as sodium borohydride, potassium borohydride or lithium borohydride. The reaction is preferably carried out in the presence of metal halides, such as calcium chloride, magnesium bromide, lithium chloride, lithium bromide or lithium iodide. Sodium trimethoxyborohydrides can also be used. When the compound of formula (II) is 4-Alkoxycarbonyl-1-phthalazone derivative, i.e. that Y in formula (II)

means an alkoxycarbonyl group, lower aliphatic alcohols, such as methanol, ethanol or propanol, it can preferably be used as a solvent, and the reaction is preferably carried out at a temperature between 0° and 150°C, and then especially between 0 and 100°C. When the compound of formula (II) means 4-chlorocarbonyl-1-phthalazone derivative, i.e. when Y in formula (II) means a chlorocarbonyl group, a solvent such as dioxane, tetrahydrofuran or benzene can preferably be used, and the reaction is preferably carried out at a temperature between 0 and 100°C, and then preferably between 0 and 50°C .

According to the embodiment of method b), a compound of formula (III) is reacted with an equimolar amount or excess [preferably 1-10 mol per mol of compound (III)] of a hydrazine derivative of formula (IV). Examples of the hydrazine derivative include hydrazine, methylhydrazine, methanesulfonylhydrazine, benzenesulfonylhydrazine and p-toluenesulfonylhydrazine. Although the reaction can be carried out in the absence of a solvent, the reaction is preferably carried out in the presence of a solvent, such as water, lower aliphatic alcohols, e.g. methanol, ethanol or propanol, and at a temperature between 0 and 150°C, preferably between 50 and 100°C. According to the embodiment of method c), the reaction can be carried out under conventional conditions used in the Grignard reaction. That is to say, the reaction is carried out in an anhydrous solvent, such as ethyl ether, benzene or tetrahydrofuran. The reaction temperature used is between 0 and 100°C, and then especially between 0 and 50°C. The Grignard compound of formula (V) is used in an amount of 1 - 3

moles per moles of the compound of formula (VI).

Regardless of which production process is used, the product can be separated and purified using conventional methods, which will be described later.

The products of the present invention can form stable salts with a pharmaceutically acceptable inorganic acid, such as sulfuric acid, hydrochloric acid, bromic acid or iodic acid, and an organic acid, such as oxalic acid, maleic acid, citric acid, tartaric acid, nicotinic acid, salicylic acid and acetylsalicylic acid. These salts are water-soluble, and they can therefore be administered in the form of injections.

The invention is illustrated by means of the following examples.

All UV spectra described in the examples are measured in 95% ethanol.

EXAMPLE- 1

To a stirred suspension of 2 g of 7-methylethoxy-4-ethoxycarbonyl-1-phthalazone in 100 ml of methanol, 3 g of sodium borohydride were added in portions. The reaction mixture was allowed to stand for 1.5 hours under reflux and in a water bath. Excess borohydride was removed by adding acetone, after which the solvent was distilled off. The residue was dissolved in water, and the solution was adjusted to pH 6 - 7 using acetic acid, and dried under reduced pressure. The residue was continuously extracted with chloroform using a Soxlet apparatus. The chloroform was distilled off from the extract, and the residue thus obtained was recrystallized in methanol, whereby 4-hydroxymethyl-7-methoxy-1-phthalazone (1.5 g) with a melting point of 229 - 230°C was obtained.

Elemental analysis:

UV spectrum: X max 222 imi (£. = 20,700)<:>, 280-nyu

(£. = 9.800), 286 mu ( £. = 9.80O),

302 mp (£. =4,800), 314 mu (£- =5,000)

32 7 mu = 3.600)

EXAMPLE 2

To a solution of 4-ethoxycarbonyl-2-phenyl-1-phthalazone (3 g)

in methanol, 150 ml, 1.2 g of sodium borohydride and 100 mg of calcium chloride were added portionwise with stirring. The reaction mixture was refluxed for 1.5 hours on a water bath.

After cooling, acetone was added to destroy excess

of borohydride and then the solvent was distilled from. The residue was dissolved in water and the solution was adjusted to pH 6-7. The solution was then extracted with chloroform. The chlorofornu extract was dried over MgSO 4 and distilled from. The residue was recrystallized from acetone to give 4-hydroxymethyl-2-phenyl-1-phthalazone 2.5 g melting at 160-162°C.

Analysis of the elements:

UV spectrum Xmax 220 mu (€_ = 35,200), 256 new

( Sr- = 6,700), 295 new ( £ = 7,800)

EXAMPLE 3

To a suspension of 4,7-diethoxycarbonyl-1-phthalazone (2 g) in 120 ml of ethanol heated at 70-80°C, sodium borohydride (1g) and 100 mg of magnesium bromide were added portionwise with stirring. After completion of the addition of borohydride, the reaction mixture was refluxed for 1.5 hours. The excess of borohydride was removed by addition of acetone and the solvent was distilled off. The remainder was dissolved in water. The pH of the solution was adjusted to 6-7 and the solution was dried under reduced pressure. The residue was extracted continuously with chloroform using a Soxlet apparatus. The chloroform was distilled from the extract and the residue was recrystallized from methanol to give 7-ethoxycarbonyl-4-hydroxy-methyl-1-phthalazone (1.4 g) melting at 206-207°C.

The product has the following structure.

Analysis of the elements:

UV spectrum: X max 215 mp. (£. = 29,lOO), 230 mu

(£- = 22,700), 252 np (= 10,600),

262 mu (€. = 11,000), 305 mu ( = 10,300), 317 new ( £• = 8,500) .

EXAMPLES 4-14

In the same way as in examples 1-3, the following products of formula (I) were obtained from the compounds of formula (IL1) in a 60 - 90% yield sDm shown in the following table 1.

EXAMPLE 15

To a stirred solution of 4-ethoxycarbonyl-2-(p-ethoxycarbonyl-phenyl)-1-phthalazone (Ig) in 50 ml of ethanol, 1 g of sodium borohydride was added portionwise at 60 - 70°C. The reaction mixture was refluxed for one hour on a water bath and the ethanol distilled off. The residue was recrystallized from methanol to give 4-hydroxymethyl-2-(p-ethoxycarbonylphenyl)-1-phthalazone, 800 mg, melting at 147 - 153°C.

Analysis of the elements:

EXAMPLES 16 - 24

In the same way as in examples 1, 2, 3 and 15, the following products of formula (I') are obtained from the compounds of formula (II<1>) in a 60 - 90% yield, as shown in the following table II .

EXAMPLE 25

A mixture of 7-bromo-4-carboxy-2-methyl-1-phthalazone (3 g) and 30 ml of thionyl chloride was carefully refluxed at 70-80°C for 50 minutes on a water bath. Excess thionyl chloride was then distilled from and; the residue was dissolved in 30 ml of dioxane. NaBH (2 g) was added portionwise to the dioxane solution at 0° - 10°C with stirring. The reaction mixture was further stirred for one hour and then the solvent was distilled off. The residue was dissolved in water and the solution was extracted with chloroform. The chloroform was distilled from the extract and the residue was recrystallized from methanol-ethyl acetate to give 7-bromo-4-hydroxymethyl-2-methyl-1-phthalazone

(1.2 g) which melts at 192 - 193°C.

EXAMPLE 26

A solution of 3-methyl-4-oxo-3,4-dihydroisocoumarin (1 g)

and 3 g of hydrazine hydrate in 30 ml of ethanol were treated under reflux for 3 hours on a water bath. The solution was cooled to room temperature and then the precipitated crystals were filtered and recrystallized from methanol to give 4-(α-hydroxyethyl)-1-phthalazone (0.8 g) melting at 158-159°C.

Analysis of the elements:

UV spectrum: Xmax 225 mp (16,100), 245 mp. (7,700),,

253 mp (8,200), 281 mu (6,400), 300 np (4,400), 312 mp. (2,800)

EXAMPLE 2 7

A solution of 6,7-dimethyl-4-oxo-3,4-dihydro-isocoumarin (3

g) and 3 g of hydrazine hydrate in 30 ml of ethanol were treated under reflux for 2 hours in a water bath. After cooling down was

the precipitated crystals filtered off and recrystallized from methanol to give 6,7-dimethyl-4-hydroxymethyl-1-phthalazone (2.6 g) melting at 253-255°C.

Analysis of the elements:

EXAMPLE 28

In the same manner as in Examples 26 and 27, 6,7-dimethyl-4-oxo-3,4-dihydroisocoumarin is reacted with methylhydrazine to obtain 2,6,7-trimethyl-4-hydroxymethyl-1-phthalazone melting at 152 - 153°C (recrystallized from ethyl acetate/petroleum ether).

EXAMPLE 2 9

A solution of 4-oxo-3,4-dihydroisocoumarin (3 g) and 3 g of p-toluenesulfonylhydrazine in 50 ml of ethanol was refluxed for 5 hours on a water bath. The ethanol was distilled off and the residue was recrystallized from ethanol-n-hexane to give 4-hydroxymethyl-2-(p-toluenesulfonyl)-1-phthalazone melting at 160-162°C.

Analysis of the elements:

EXAMPLE 3Q

In the same manner as in Example 2.6, 7-chloro-8-amino-4-oxo-3,4-dihydroisocoumarin was allowed to react with hydrazine to give 7-chloro-8-amino-4-hydroxymethyl-1-phthalazone melting at 232 ° - 234-°C (recryst. from methanol) in a yield of 67%.

UV spectrum: X max 220 mu (24-, 800), 255 mp (9,000),

2 70 mu (9,000), 2 96 mu (11,800)

EXAMPLE 31

One. solvation of a Grignard compound was prepared from

1 g of magnesium ribbon and 5.86 g of methyl iodide in 100 ml of abs, ethyl ether by a conventional method. To the Grignard reagent as described above, a solution of 4-ethoxycarbonyl-1-phthalazone (2.5 g) in 50 ml of tetrahydrofuran is added dropwise at 10 - 15°C with stirring. The reaction mixture was refluxed for 2 hours and then 10% H 2 SO 4 sodium was added slowly. The precipitated crystals were filtered and recrystallized from ethanol to give 4-(α-hydroxyisopropyl)-1-phthalazone (2.0 g) melting at 212-213°C. The compound has the following structure-

Analysis of the elements:

EXAMPLES 32-38

In the same way as in example 31, the following products of formula (I) were obtained from the compounds of formula (II<1>) in an 85-95% yield, as shown in the following table III.

EXAMPLE 39

The compounds from the present invention show a preventive effect in terms of increasing the coagulation ability and susceptibility to thrombosis by injection treatment of animals with cholesterol or adrenaline, and which is shown below.

After oral administration of 10 mg/kg of the compound according to

present invention to a rabbit, the intensity of platelet aggregation induced by adenosine diphosphate was measured by Born's method (Born, J. Physiol 162, 67

(1962), see also O'Brien, J. Clin. Path. 15, 452 (1962), Lancet, 1, 779 (1968)-.

A rabbit was injected with adrenaline (1 ug/kg) 3 hours after oral administration of the sample. 5 minutes after the injection, 4.5 mg of blood was taken from the carotid artery and then diluted with 0.5 ml of a 3.8% solution of sodium citrate. After centrifugation of the blood at 1000 g for 30 minutes, aliquots of each 0.9

ml taken from the supernatant solution. For each aliquot

-5 -4

0.1 ml of 3 x 10 mol and 10 mol solutions of adenosine diphosphate were added. The: molar concentrations of ADP in 10-^ 10-^. the platelet aggregation was measured using the "platelet aggregation meter" (model 169, Evans Elect. Ltd. England). The intensities of ADP-induced platelet aggregation are shown as a percentage of the pre-injected amount. As shown in the following table IV, the compounds according to the present invention show lower values for ADP-induced platelet aggregation, whereby they thus prevent increase. of coagulation ability and thrombosis. The following table also shows LD^ values for compounds according to the invention.

EXAMPLE 4Q

Effect of compounds for the prevention of experimental atherosclerosis

The compounds according to the present invention show a very good effect with regard to the prevention of atherosclerosis, thereby inhibiting cholesterol deposition on the arterial wall in experimental atherosclerosis. 95 healthy male rabbits were each fed daily with 150 g pellets containing 1% cholesterol over a period of 15 weeks. Then 5 of the above rabbits were sacrificed. The remaining 90 rabbits were divided into six groups. While all groups were fed with standard f6r, 5 groups were each administered with 10 mg per kg of the compound according to the present invention, whereby the one remaining group was administered an ineffective drug ("placebo") containing potato starch.

After 6, 10 and 20 weeks, 5 rabbits from the six groups were sacrificed, and the total content of cholesterol in the arterial wall was determined by gas chromatography. The results are shown in table V. 1. The total cholesterol content at the end of the first

The 15 weeks were 48.09 - 11.6 pg/mg dry weight.

2. The total cholesterol-containing from. the six groups are shown in the following table. The content is stated in ug unit per one mg of the dry arterial wall. The value in the table is an average value of 5 rabbits.

EXAMPLE 41

In the same way as in example 3, the following 7-alkoxycarbonyl-4-hydroxymethyl-1-phthalazones were obtained from the corresponding 4,7-dimethoxycarbonyl-1-phthalazones in a 50-80% yield.

7-isopropoxycarbonyl-4-hydroxymethyl-1-phthalazone: m.p. 212 - 213°C. (recrystallized from acetone/hexane)$

7-n-butoxycarbonyl-4-hydroxymethyl-1-phthalazone: m.p. 144 - 146°C. (recrystallized from ethyl acetate)$

7-isobutoxycarbonyl-4-hydroxymethyl-1-phthalazone: m.p. 160 - 162°C. (recrystallized from ethyl acetate).

95 healthy male rabbits were each fed daily with 150 g pellets containing 1% cholesterol over a period of 15 weeks. Then 5 of the above rabbits were sacrificed. The remaining 90 rabbits were divided into six groups. While all groups were fed with standard f6r, 5 groups were each administered with 10 mg per kg of the compound according to the present invention, whereby the one remaining group was administered an ineffective drug ("placebo") containing potato starch.

After 6, 10 and 20 weeks, 5 rabbits from the six groups were sacrificed, and the total content of cholesterol in the arterial wall was determined using gas chromatography. The results are shown in table V. 1. The total cholesterol content-L at the end of the first

The 15 weeks were 48.09 11.6 ug/mg dry weight.

2. The total cholesterol content from the six groups is shown in the following table. The content is stated in ug unit per one mg of the dry arterial wall. The value in the table is an average value of 5 rabbits.

EXAMPLE 41

In the same way as in example 3, the following 7-hydroxycarbonyl-4-hydroxymethyl-1-phthalazones were obtained from the corresponding 4,7-dimethoxycarbonyl-1-phthalazones in a 50-80% yield.

7-isopropoxycarbonyl-4-hydroxymethyl-1-phthalazone: m.p. 212 - 213°C. (recrystallized from acetone/hexane) ;

7-n-butoxycarbonyl-4-hydroxymethyl-1-phthalazone: m.p. 144 - 146°C. (recrystallized from ethyl acetate) ;

7-isobutoxycarbonyl-4-hydroxymethyl-1-phthalazone: m.p. 160 - 162°C. (recrystallized from ethyl acetate).

Effect of inhibition against cyclic AMP phosphodiesterase in blood vessels and platelets.

The supernatant of homogenized inner, middle portion of the aortic wall from experimental animals or platelet-rich plasma was incubated with the reagent mixture consisting of tritum-labeled cyclic AMP (adenosine-3',5'-cyclic monophosphate) and various amounts of the compound.

The incubated mixture was purified by column chromatography

and the fraction containing nucleoside was analyzed quantitatively by liquid scintillation counter.

With regard to the details of the experimental procedure, reference is made to the report by Hidaka et al. in Biomedical Medicine, vol. 10, pages 301-311 (1974).

Table VI shows the inhibition effect for these compounds

against cyclic AMP phosphodiesterase. The indications in the table show the quantity of the compound which is necessary to achieve

50% inhibition of cyclic AMP, phosphodiesterase.

Claims (1)

Analogous process for the production of therapeutically active phthalazone derivatives or acid salts thereof with the general formula I where R means a hydrogen atom or a lower alkyl group, R^ means a hydrogen atom, a lower alkyl, lower alkylsulfonyl or phenyl or tolyl or a phenyl group of the general formula where R4 means a hydrogen or halogen atom, a lower alkyl or lower alkoxy group, R,, means a hydrogen or halogen atom, a lower alkyl, lower alkoxy or lower alkoxy carbonyl group, R 2 means a hydrogen or halogen atom, a lower alkyl or lower alkoxy group, R 2 means a hydrogen or halogen atom, a lower alkyl, lower alkoxy, lower alkoxycarbonyl, amino or acetamido group, and under the preceding -r J- sentence that R, R^, R o and R^ do not simultaneously mean a hydrogen atom, characterized in that one: (a) :: allows a compound with the general formula II: where R 1 , R 2 and R 2 have the same meanings as stated in formula (I), and where Y means an alkoxycarbonyl group or a halogen carbonyl group, reacting with an alkali metal borohydride in the presence or absence of a metal halide; or (b) leaves a compound of that general formula where R, R2 and R^ have the same meanings as indicated - f formula (I) , react with a hydrazine derivative of the formula where R^. has the same meaning as in formula (I), with the exception of an aryl group; or . (c) allows a connection with the general formula ' "\_V»<».«r ■ ■ ■ ... .ivor R^, R2 and R3 have the same meanings as stated in formula (I), and where > Z means an alkoxycarbonyl-, an aldehyde or acyl group, . }..' .. 1 V " react with. a Grignard compound of the formula where R has the same meanings as given in formula (I) with the exception of a hydrogen atom, and where , X means a halogen atom, and, if desired, reacting each of the reaction products from (a), (b) and (c) above with an acid.