Imidazo [1,5-a]pyrimidine derivatives and process for their preparation

Abstract

This invention relates to a novel imidazo[1,5-a]pyrimidine derivatives and process for their preparation.Moreover, it relates to novel imidazo[1,5-a]pyrimidine derivatives and salts thereof having antifungal activities, and process for their preparation.

Description

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to a new class of compounds of the imidazo [1,5-a]pyrimidine series. It relates also to the synthesis of such substances. It is concerned further with salts of these compounds such as hydrochloride, sulfate, acetate, tartrate and methanesulfonate.

These new compound of the invention have the general formula (I), ##STR1## wherein R.sub.1 is a halogen atom, R.sub.2 is a hydrogen atom or a halogen atom, X is a sulfur atom, a sulfinyl group, a sulfonyl group or an oxygen atom, m and n are each independently 0 or 1, A is a phenyl group which may be substituted, a cycloalkyl group or a aromatic heterocyclic group which may be substituted (but when m is 0 and A is a phenyl group which may be substituted or a cycloalkyl group, R.sub.2 is not a hydrogen atom).

It has been found that these compounds possess valuable pharmacological properties. For instance they produce antifungal effects and may be used for therapeutic properties.

Recently, fungal diseases are on the increase internationally because of frequent use of broad spectrum antibiotics, steroid hormones and immunosuppressive agents et cetera. However, useful antifungal agents in therapy of fungal diseases are limited. At present, it might almost be said that the only drugs for fungal diseases are polyenmacrolide and imidazole derivatives. It has been hoped that more useful antifungal agents for treatment of fungal disease could be developed. Therefore, we have studied earnestly to develop compounds having useful activity, especially potent antifungal activity. As a result of out study, we have found novel imidazo[1,5-a]pyrimidine derivatives having different structures and high potency against various organisms as compared with known antifungal agents. The compounds of the present invention and their salts are new compounds which have not been disclosed in any references. The present compounds may be used not only as a medicines for humans, but also as drugs for animals, fishes and shellfish, and as antiseptics for food in the various forms.

As suitable salts of the compounds represented by the formula (I), there may be mentioned salts derived from inorganic acid, such as, for example, hydrochloric acid, sulfuric acid, or salts derived from organic acids, such as, for example, acetic acid, tartaric acid, methanesulfonic acid, or the like.

These new compounds can be prepared by the method mentioned below.

The N-acylaminomethylpyrimidine compounds represented by the formula (II) were converted to the imidazo[1,5-a]pyrimidine compounds having the formula (III) by the condensing agents such as phosphorous halide and phosphoryl halide, for example phosphorous trichloride, phosphorous pentachloride, phosphorous tribromide, phosphoryl chloride, and thionyl chloride. ##STR2## wherein A, X, m, n and R.sub.1 have the previously defined meanings, R is a halogen atom.

If necessary, the compound represented by the formula (III) can be converted to the compound represented by the formula (IV) by treatment with a halogenation agent such as N-bromosuccinimide, N-chlorosuccinimide. The compound having a thio group in the formula (III) or (IV) can also be oxidized; the thio group to sulfinyl or sulfonyl group by the usual manner.

N-acylaminomethylpyrimidine compounds having the formula (II), the starting materials in the reaction discussed above, are also novel compounds and can be prepared by the following methods.

The method for preparing these compounds involves (a) reaction of glycine ethyl ester hydrochloride with various acid chlorides to give N-acyl derivatives of glycine ethyl ester and (b) treatment of these N-acyl derivatives with malonamide to give the desired compounds (II). These reactions are summarized in the following scheme. ##STR3## wherein A, X, m and n have the previously defined meanings, R.sub.3 is a lower alkyl group.

PREPARATION OF INTERMEDIATE COMPOUNDS

REFERENCE 1

Preparation of 2-[N-(2-thenoyl)aminomethyl]-4,6-dihydroxypyrimidine

(i) N-(2-thenoyl)glycine ethyl ester

To a solution of glycine ethyl ester hydrochloride (22 g) and potassium carbonate (86 g) in water (600 ml) was added a mixture of benzene (600 ml) and ether (400 ml) and stirred at room temperature. 2-Thenoyl chloride (25 g) in benzene (100 ml) was added during a period of about 30 minutes under stirring and then the mixture was stirred for 2 hours at room temperature. The organic layer was separated and after dried over anhydrous sodium sulfate, concentrated under reduced pressure to give colorless crystals, which were recrystallized from ethanol to obtain the objective compound (23 g), mp 82.degree.-83.degree. C.

(ii) 2-[N-(2-thenoyl)aminomethyl]-4,6-dihydroxypyrimidine.

To a solution of sodium (1.4 g) in ethanol (120 ml) was added malonamide (3.8 g) and the mixture was heated at 60.degree. C. for an hour under stirring. Then after added N-(2-thenoyl)glycine ethyl ester (8 g), the mixture was refluxed for 6 hours. The mixture was concentrated to give the residue which was diluted with water. The aqueous mixture was neutralized by adding acetic acid to deposit a crystalline product which was collected by filtration and recrystallized from dimethylformamide (DMF) to give the objective product (2.8 g) as colorless crystals, mp 270.degree.-275.degree. C. (decompd.).

Analysis (%) for C.sub.10 H.sub.9 N.sub.3 O.sub.3 S, Calcd. (Found): C, 47.80 (47.83); H, 3.61 (3.67); N, 16.72 (16.96).

Other compounds prepared by the same manner as this example are as follows.

__________________________________________________________________________ ##STR4##Referenceexample A X m n formula mp (.degree.C.)__________________________________________________________________________ ##STR5## -- 0 0 C.sub.15 H.sub.12 N.sub.4 O.sub.4 220-225 (decompd.)3 ##STR6## -- 0 0 C.sub.10 H.sub.9 N.sub.3 O.sub.4 285-290 (decompd.)4 ##STR7## -- 0 1 C.sub.11 H.sub.11 N.sub.3 O.sub.3 S 275-285 (decompd.)5 ##STR8## -- 0 0 C.sub.10 H.sub.9 N.sub.3 O.sub.3 S >3006 ##STR9## -- 0 0 C.sub.10 H.sub.8 N.sub.3 O.sub.3 BrS 250-255 (decompd.)7 ##STR10## -- 0 0 C.sub.10 H.sub.8 N.sub.3 O.sub.3 ClS >3008 ##STR11## -- 0 0 C.sub.11 H.sub.11 N.sub.3 O.sub.3 S 269-276 (decompd.)9 ##STR12## -- 0 0 C.sub.11 H.sub.10 N.sub.4 O.sub.3 255-260 (decompd.)10 ##STR13## -- 0 0 C.sub.14 H.sub.10 N.sub.3 O.sub.3 SCl 185-195 (decompd.)__________________________________________________________________________

EXAMPLE 1

2,4-dichloro-6-(2-thienyl)imidazo[1,5-a]pyrimidine

A mixture of 2-[N-(2-thenoyl)aminomethyl]-4,6-dihydroxypyrimidine (1.3 g) and phosphoryl chloride (10 ml) was heated to reflux for 3 hours. The excess phosphoryl chloride was removed by distillation under reduced pressure. To the resulting residue was added an aqueous sodium carbonate solution and the mixture was extracted with chloroform. The chloroform layer was washed with water, dried over anhydrous sodium sulfate and concentrated. The residue was purified by alumina column chromatography, eluting with benzene and then by recrystallization to give the objective compound (0.56 g) as yellow plates, mp 152.degree.-153.degree. C.

Analysis (%) for C.sub.10 H.sub.5 N.sub.3 SCl.sub.2, Calcd. (Found): C, 44.46 (44.32); H, 1.87 (1.67); N, 15.56 (15.56).

Other compounds prepared by the same manner as this example are as follows.

__________________________________________________________________________ ##STR14## Analysis Calcd. (%) FoundExample R.sub.1 R.sub.2 A X m n Formula mp (.degree.C.) C H N__________________________________________________________________________2 Cl H ##STR15## -- 0 0 C.sub.15 H.sub.8 N.sub.4 OCl.sub.2 149-150 54.40 54.37 2.43 2.18 16.92 16.873 Cl H ##STR16## -- 0 0 C.sub.10 H.sub.5 N.sub.3 OC1.sub.2 116-117 47.27 47.08 1.98 1.80 16.54 16.684 Cl H ##STR17## -- 0 1 C.sub.11 H.sub.7 N.sub.3 Cl.sub.2 S 86-87 46.49 46.21 2.48 2.30 14.79 14.925 Cl H ##STR18## -- 0 0 C.sub.10 H.sub.5 N.sub.3 Cl.sub.2 S 146-147 44.46 44.25 1.87 1.68 15.56 15.686 Cl H ##STR19## -- 0 0 C.sub.10 H.sub.4 N.sub.3 Cl.sub.2 Sbr 164-165 34.41 34.67 1.16 1.03 12.04 12.097 Cl H ##STR20## -- 0 0 C.sub.10 H.sub.4 N.sub.3 Cl.sub.3 S 166-167 39.43 39.29 1.32 1.16 13.80 13.998 Cl H ##STR21## -- 0 0 C.sub.11 H.sub.7 N.sub.3 Cl.sub.2 S 117-118 46.49 46.39 2.48 2.36 14.79 15.009 Cl H ##STR22## -- 0 0 C.sub.11 H.sub.6 N.sub.4 Cl.sub.2 140-142 (dec.) 49.84 49.81 2.28 2.11 21.13 21.3210 Cl H ##STR23## -- 0 0 C.sub.14 H.sub.6 N.sub.3 Cl.sub.3 S 173-175 47.42 47.41 1.71 1.53 11.85 12.0011 Cl H ##STR24## S 1 1 C.sub.13 H.sub.9 N.sub.3 Cl.sub.2 S 111-112 50.34 50.41 2.92 2.79 13.55 13.6012 Cl H ##STR25## S0 1 1 C.sub.13 H.sub.9 N.sub.3 Cl.sub.2 SO 153-154 47.87 47.89 2.78 2.69 12.88 12.80__________________________________________________________________________

EXAMPLE 13

2,4,8-trichloro-6-phenylimidazo[1,5-a]pyrimidine

A mixture of 2,4-dichloro-6-phenylimidazo[1,5-a]pyrimidine (0.88 g), N-chlorosuccinimide (0.5 g) and benzoyl peroxide (0.04 g) in carbon tetrachloride (20 ml) was heated to reflux for 14 hours. The mixture was concentrated and purified by alumina column chromatography, eluting with benzene to give the objective product which was recrystallized from ethanol to yellow plates (0.32 g), mp 133.degree.-134.degree. C.

Analysis (%) for C.sub.12 H.sub.6 N.sub.3 Cl.sub.3, Calcd. (Found): C, 48.28 (48.36); H, 2.03 (1.81); N, 14.07 (14.35).

Other compounds prepared by the same manner as this example are as follows.

__________________________________________________________________________ ##STR26## Analysis Calcd. (%) FoundExample R.sub.1 R.sub.2 A X m n Formula mp (.degree.C.) C H N__________________________________________________________________________14 Cl I ##STR27## -- 0 0 C.sub.13 H.sub.8 N.sub.3 Cl.sub.2 I 192-193 38.65 38.65 2.00 1.90 10.40 10.3915 Cl Br ##STR28## -- 0 0 C.sub.13 H.sub.8 N.sub.3 BrCl.sub.2 194-195 43.73 43.49 2.26 2.13 11.77 11.2716 Cl Cl ##STR29## -- 0 0 C.sub.12 H.sub.4 N.sub.3 Cl.sub.5 186-187 39.23 39.29 1.10 0.93 11.44 11.5717 Cl Cl ##STR30## -- 0 0 C.sub.12 H.sub.5 N.sub.3 BrCl.sub.3 182-183 38.19 38.25 1.34 1.12 11.13 11.1518 Cl Cl ##STR31## -- 0 1 C.sub.13 H.sub.7 N.sub.3 Cl.sub.4 116-117 44.99 45.12 2.03 1.90 12.01 12.0319 Cl Cl ##STR32## -- 0 0 C.sub.12 H.sub.12 N.sub.3 Cl.sub.3 153-154 47.32 47.32 3.97 3.82 13.79 13.94__________________________________________________________________________

EXPERIMENT 1

Antifungal spectra

The antifungal activity of the compound of the present invention was assayed by the standard agar dilution streak method against fungi. The results were shown in Table 1. M.I.C. studied with representative members of the compound of this invention have demonstrated extremely favorable antimycotic activity, so that these compounds will be very useful as therapeutic for agents, drugs for animals, fishes and shellfish, and an antiseptic for food.

__________________________________________________________________________Antifungal activity Minimum inhibitory concentration (.mu.g/ml)Organism Exp. 1 Exp. 3 Exp. 4 Exp. 5 Exp. 6 Exp. 7 Exp. 8 Exp. 13 Exp. 17 Exp. Exp.__________________________________________________________________________ 19Candida albicans 3147 3.13 3.13 3.13 3.13 0.78 0.20 1.56 3.13 1.56 1.56 0.78Candida albicans IFO-1388 1.56 3.13 6.25 6.25 0.78 0.78 6.25 3.13 0.78 0.20 0.20Candida albicans IFO-1594 1.56 3.13 3.13 3.13 3.13 0.20 6.25 3.13 1.56 3.13 1.56Candida albicans MTU-12124 6.25 6.25 6.25 6.25 0.78 1.56 3.13 12.5 3.13 6.25 1.56Candida albicans KYF-602 6.25 12.5 6.25 12.5 3.13 0.39 6.25 3.13 6.25 25 1.56Candida stellatidea 1.56 3.13 3.13 6.25 0.78 0.78 1.56 6.25 0.39 0.78 1.56IFO-1398Microsporum canis 200100 1.56 1.56 1.56 1.56 0.78 -- -- 0.78 -- -- --Aspergillus 6.25 12.5 12.5 3.13 3.13 -- -- 6.25 -- -- --fumigatus MTU-06002 Trichophyton 1.56 3.13 1.56 1.56 1.56 0.78 1.56 0.78 3.13 3.13 3.13mentagrophytes MTU-19003Trichophyton 1.56 3.13 1.56 0.78 0.78 0.78 1.56 0.78 3.13 1.56 1.56mentagrophytes MTU-19005__________________________________________________________________________

EXPERIMENT 2

In vivo antifungal activity against systemic infection in mice (ICR)

Mice were infected intraperitoneal with Candida albicans. (Strain KYF-1385, challenge dose 2.6-7.2.times.10.sup.6 cfu/mouse, n=5). After the infection, compounds were administered 100 mg/kg/day twice a day during 4 days, oral administration.

The efficacy of the compounds of the invention is shown in the Figure together with a control (no treatment).

The present compounds were more effective than the control. ##STR33## Effect of present compounds on urine systemic candidosis by oral administration

Claims

1. A compound selected from the group consisting of a free base and its acid addition salts, said free base having the formula (I), ##STR34## wherein R.sub.1 is a halogen atom, R.sub.2 is a hydrogen atom or a halogen atom, X is a sulfur atom, a sufinyl group, a sulfonyl group or an oxygen atom, m and n are each independently 0 or 1, A is a phenyl group which may be substituted by 1 or 2 substituents selected from the group consisting of methyl, bromine, and chlorine, a C.sub.3-6 cycloalkyl group or an aromatic heterocyclic group selected from the group consisting of ##STR35## which may be substituted by 1 phenyl, bromine, chlorine, or methyl; with the proviso that when m is 0 and A is a phenyl group which may be substituted or a cycloalkyl group, R.sub.2 is not a hydrogen atom.

2. An agent for treatment of fungal diseases comprising a compound as claimed in claim 1 and a pharmaceutically acceptable carrier.