WO1994011367A1 - 2-(pyrid-2'-yl)-2-thiazoline-4(s)-carboxylic acid derivatives - Google Patents

Abstract

2-(Pyrid-2'-yl)-2-thiazoline-4-carboxylic acid derivatives of formula (I) in which R1 represents hydrogen, halogen, hydroxy, C1-C4 alkoxy or C1-C4 alkyl; R2 represents hydroxy or resterified hydroxy; and R3 represents etherified hydroxy or a group of the partial formula -N(R4, R5) in which R4 and R5 independently from each other represent hydrogen or C1-C4 alkyl or in which R4 represents hydroxy or esterified hydroxy and R5 represents hydrogen, C1-C4 alkyl or a group -X-R6 in which X is C2-C12 alkylen or oxaalkylen having 4-12 chain members and R6 represents C1-C2 alkyl or a hydroxylamino group -N(OH)-R7 in which R7 represents C1-C4 alkanoyl; and salts thereof form chelate-type metal complexes with trivalent metal ions, especially iron (III), and can be used, for example, for the treatment of pathological conditions in warm-blooded animals that are associated with an excess of trivalent metal ions in the body. Valuable starting material embraces alkali and alkaline earth salts of 2-(3'hydroxypyrid-2'-yl)-2-thiazoline-4(S)-carboxylic acid.

Description

2-(Pyrid-2^,-yl)-2-thiazoline-4(S)-carboxylic acid derivatives

The invention relates to novel derivatives of 2-(pyrid-2'-yl)-2-thiazoline-4(S)-carboxylic acid, processes for their manufacture, pharmaceutical compositions containing such compounds, and the use of these derivatives. The invention is also directed to alkali and alkaline earth metal salts of 2-(3'hydroxypyrid-2'-yl)-2-thiazoline-4(S)-carboxylic acid which represent valuable starting material and exhibit valuable therapeutical properties.

The invention relates especially to 2-(pyrid-2'-yl)-2-thiazoline-4(S)-carboxylic acid derivatives of the formula (I)

in which R_j represents hydrogen, halogen, hydroxy, C1-C₄ alkoxy or -C₄ alkyl; R₂ represents hydroxy or esterified hydroxy; and R₃ represents etherified hydroxy or a group of the partial formula -N(R₄,Rs) in which R₄ and R₅ independendy from each other represent hydrogen or -C₄ alkyl or in which R₄ represents hydroxy or esterified hydroxy and R₅ represents hydrogen, C_rC alkyl or a group -X-R in which X is C^-C^ alkylen or oxaalkylen having 4-12 chain members and Rg represents Cj-C-₂ alkyl or a hydroxylamino group -N(OH)-R₇ in which R₇ represents C_rC₄ alkanoyl; and salts thereof, processes for the manufacture of these compounds, pharmaceutical compositions containing such compounds and the use of these compounds.

The compounds of the formula (I) are characterized by the asymmetric carbon atom C4 marked with an asterisk. The bonds surround C4 are arranged tetrahedrally, and the substituents are in fixed positions. Thus the compounds of formula (I) represent optical antipodes exhibiting (S) conformation as shown in example (i) below:

^xc ^SC

(i) I (ii) I

H COR₃

(S) conformation (R) conformation

Contrary to the compounds of the formula (I) according to the present invention, 2-(3'-hydroxypyrid-2-yl)-Δ²-thiazoline-4(R)-carboxylic acid (desmethyldesferrithiocin), its sodium salt and its methyl ester which are described by Bergeron et al. [Journal of Medical Chemistry, Vol.34, No.7, pp 2072-78 (July 1991)] exhibit the (R) conformation illustrated in example (ii) above. Racemic 2-(3'-hydroxypyrid-2-yl)-Δ²-thiazoline-4- carboxylic acid and racemic lower alkyl esters thereof are also known and described in U.S. Patent No. 4,406,905.

In contrast to the (R) comformers described by Bergeron et al. and the racemates described in U.S. Patent No. 4,406,905 the present invention is exclusively directed to (3'-hydroxypyrid-2-yl)-Δ²-thiazoline derivatives showing (S) conformation because it surprisingly was found that the (S) conformers have significant therapeutical advantages over the known compounds.

A therapeutically preferred subgroup within the formula (I) consists of those representatives wherein

(a) Ri represents hydrogen, halogen, hydroxy, C_rC₄ alkoxy or C_rC₄ alkyl; R₂ represents hydroxy or esterified hydroxy; and

R₃ represents, together with the carbonyl group to which it is attached, an esterified carboxyl group that can be cleaved under physiological conditions or a group of the partial formula -N(R ,R₅) in which R₄ and R₅ independently from each other represent hydrogen or C-t-0₄ alkyl or in which R₄ represents hydroxy or esterified hydroxy and R₅ represents hydrogen, -C₄ alkyl or a group -X-R₆ in which X is C₂-C₁₂ alkylen or oxaalkylen having 4-12 chain members and R₆ represents

alkyl or a hydroxylamino group -N(OH)-R₇ in which R₇ represents C_rC₄ alkanoyl; or

(b) R_j represents hydrogen, halogen, hydroxy, C_rC₄ alkoxy or C_rC alkyl; R₂ represents esterified hydroxy; and

R₃ represents C_rC alkoxy; or (c) Rι represents halogen, hydroxy or -C₄ alkoxy;

R₂ represents hydroxy; and

R₃ represents C_rC alkoxy; and salts thereof.

Among this subgroup the (a) type compounds are mostly preferred.

Within the scope of the present description, the definitions used hereinbefore and hereinafter have preferably the following meanings:

Halogen R-. is, for example, fluorine or chlorine.

alkoxy is, for example, ethoxy or, especially, methoxy. C₁-C alkyl is, for example, corresponding unbranched alkyl such as ethyl, n-propyl or, especially, methyl.

alkyl R₆ is especially methyl.

Esterified hydroxy R₂ and R₄ is especially coιτesponding esterified hydroxy which is cleavable (that is to say metabolisable) under physiological conditions. Such metabolisable esterified hydroxy groups are known in the art. Corresponding esterified hydroxy R₂ or R₄ is, for example, a radical -O-Ac in which Ac represents the acyl radical of a carbonic acid semiester, in particular carbonic acid semi-C₁-C₄-alkyl ester or carbonic acid semi-oxaalkyl ester in which oxaalkyl has 4-13 chain members, such as an acyl radical -C(=O)-(O-CH₂-CH₂)_n-O-Alk in which n is an integer from 0 to 4 and Alk represents C_rC₄ alkyl, in particular methyl or ethyl. Such acyl groups Ac are, for example, methoxycarbonyl, ethoxycarbonyl or 2-(methoxyethoxy)-ethoxycarbonyl. Further acyl radicals Ac are, for example, -C₃ alkanoyl such as acetyl or propionyl, or monosubstituted or disubstituted carbamoyl such as di-C₁-C₄-alkyl carbamoyl, for example dimethylcarbamoyl or diethylcarbamoyl, or C₁-C -alkoxycarbonyl-C₁-C₄-alkyl- carbamoyl, for example methoxycarbonylmethylcarbamoyl, ethoxycarbonylmethyl- carbamoyl or 2-ethoxycarbonylethylcarbamoyl.

Etherified hydroxy R₃, together with the carbonyl group to which it is attached, forms, for example, -C₄ alkoxycarbonyl or an esterified carboxyl group that can be cleaved under physiological conditions. -C₄ alkoxycarbonyl as group -COR₃ is, for example, corres¬ ponding unbranched alkoxycarbonyl such as ethoxycarbonyl, n-propoxycarbonyl or, especially, methoxycarbonyl. Esterified carboxy groups -COR₃ that can be cleaved under physiological conditions are known in the art. Suitable groups are especially C₁-C₄-alkan- oyloxymethoxycarbonyl such as acetoxymethoxycarbonyl or pivaloyloxymethoxy- carbonyl, Cι-C₄-alkoxycarbonyloxy-Cj-C₄-alkoxycarbonyl such as methoxycarbonyloxy- methoxycarbonyl or ethoxycarbonyloxymethoxycarbonyl, or 2-oxo-l,3-dioxolen-4-yl- methoxycarbonyl that is optionally substituted in the 5-position of the dioxolen ring by C C alkyl, for example methyl, or phenyl. A further suitable esterified carboxy group that can be cleaved under physiological conditions is a group

-C(=O)-(O-CH₂-CH₂)_m-O-Alk in which m is an integer from 1 to 4 and Alk represents C_j-C₄ alkyl, in particular methyl or ethyl. Such groups are, for example, 2-(methoxy- ethoxy)-ethoxycarbonyl or 2-[2-(methoxyethoxy)-ethoxy]-ethoxycarbonyl.

C₂-C₁₂ alkylen X is, for example, corresponding unbranched alkylen such as 1,4-butylen, 1,5-pentylen, 1,6-hexylen, 1,7-heptylen, 1,8-octylen, 1,9-nonylen or 1,10-decylen. Oxaalkylen having 4-12 chain members is, especially, corresponding unbranched (straight-chained) alkylen that is interrupted by 1 to 4 oxygen atoms provided that the individual oxygen atoms are separated from each other by at least two carbon atoms, such as the radical -(CH₂-CH₂-O)_m- in which m is an integer from 1 to 4 and the first CH₂ group is attached to the carboxamide N-atom. Corresponding groups are, for example, dioxyethylene and trioxyethylene.

C_rC₄ alkanoyl R₇ is, for example, formyl, acetyl or propionyl.

In this description, the term "lower" used in connection with definition of groups and compounds denotes, unless expressly defined otherwise, that the groups or compounds so designated contain from 1 to 7, more especially, from 1 to 4, carbon atoms.

The compounds of the formula (I), for example those in which the radical R_x and/or R₂ represents hydroxy and/or the radical -COR₃ represents a group of the partial formula -CON(R₄,R5) in which R represents hydroxy and R₅ has the above meanings, are capable of forming salts. The salts of the compounds according to the invention are, especially, pharmaceutically acceptable, non-toxic salts. Such salts are especially metal salts and ammonium salts, such as alkali metal or alkaline earth metal salts, for example sodium, potassium, magnesium or calcium salts as well as related 2+ salts such as zinc salts, and ammonium salts with ammonia or suitable organic amines, there coming into consideration for the salt formation especially aliphatic, cycloaliphatic, cycloaliphatic- aliphatic or araliphatic primary, secondary or tertiary mono-, di- or poly-amines, and also heterocyclic bases. Such amines are, for example, lower alkylamines, for example triethylamine, hydroxy-lower alkylamines, for example 2-hydroxyethylamine, bis-(2-hydroxyethyl)-amine or tris-(2-hydroxyethyl)-amine, basic aliphatic esters of carboxylic acids, for example 4-aminobenzoic acid 2-diethylaminoethyl ester, lower alkyleneamines, for example 1-ethylpiperidine, cycloalkylamines, for example dicyclo- hexylamine, or benzylamines, for example N,N'-dibenzyl-ethylenediamine, also bases of the pyridine type, for example pyridine, collidine or quinoline. Further salts are internal salts (zwitterionic forms of compounds of the invention), wherein a basic group, for example the basic nitrogen atom present in the pyridine ring, is protonated by a hydrogen ion originating from an acidic group in the molecule of the formula (I). The compounds of the formula (I) can also form intermolecular (as opposed to intramolecular, i.e. zwitterionic) acid addition salts, for example with inorganic acids, such as hydrochloric acid, sulphuric acid or phosphoric acid, or with suitable organic carboxylic or sulphonic acids, for example methanesulfonic acid, or with amino acids, such as arginine and lysine.

For isolation and purification, pharmaceutically unacceptable salts also can be used. Only the pharmaceutically acceptable, non-toxic salts are used for therapeutic application and, for that reason, they are preferred.

The compounds of the formula I, for example those having a group of the partial formula -N(R₄,R₅) in which R represents hydroxy and R5 has the above meanings, are capable of forming stable complexes with metal ions, such as heavy metal ions. Of the heavy metal ions, there may be mentioned especially those in the 3+ oxidation state, such as Al³⁺ or, most especially, Fe³⁺. Such metal ion complexes are comprised by the term "salts" and are also a subject of the present invention .

The substances of the formula (I) possess pharmacologically valuable properties. Owing to their ability to form stable complexes with heavy metal ions, especially with those in the 3+ oxidation state, such as Al³⁺ or, most especially, with Fe³⁺, the compounds of the formula (I) having a metabolisable carboxy ester group (R₃ together with the carbonyl group to which it is attached, forms an esterified carboxyl group that can be cleaved under physiological conditions) or a group of the partial formula -N(R₄,R₅) in which R represents hydroxy and R₅ has the above meanings, prevent, for example, the deposition of iron-containing pigments in the tissues and, in cases where iron has been deposited in the organism, bring about elimination of the iron, for example in haemochromatosis and haemosiderosis and also in cirrhosis of the liver. They can also be used for the elimination from the organism of other heavy metals, for example aluminium and also chromium and copper. Thus, the compounds of the formula I can also be used in the case of dialysis encephalopathy, osteomalacia and Alzheimer's disease. For the purpose of eliminating heavy metal ions, for example iron(III) ions, it is also possible to use compounds of the formula (I) having a suitably esterified phenolic hydroxy group (R₂ is esterified hydroxy and, optionally, Rj is an esterified hydroxy group) and/or esterified hydroxylamine hydroxyl group (R₄ is esterified hydroxy), the ester grouping(s) of which is (are) readily cleaved under physiological conditions (prodrug forms).

On the other hand, owing to their high solubility and good tolerability, the metal ion complexes of compounds of the formula (I) in which Rj has the above meanings, R₂ represents hydroxy and R₃ represents a group of the formula -N(R ,R₅) in which R₄ represents hydroxy and R₅ has the above meanings, especially with suitable paramagnetic and/or radioactive metals, can be used as contrast agents in diagnostic medicine, for example X-ray, radionuclide, ultrasound and/or magnetic resonance diagnostics.

In one preferred embodiment the present invention is directed to compounds of the formula I in which R₃ represents etherified hydroxy or a group of the partial formula -N(R₄,R₅) in which R₄ and R₅ independently from each other represent hydrogen or C C₄ alkyl and Ri and R₂ have the above meanings, and salts thereof.

In another preferred embodiment the present invention is directed to compounds of the formula I in which R₃ represents a group of the partial formula -N(R ,R₅) in which R₄ represents hydroxy or esterified hydroxy and R₅ represents hydrogen, -C₄ alkyl or a group -X-R in which X is ^-C^ alkylen or oxaalkylen having 4-12 chain members and R₆ represents Cj-Cj' lkyl or a hydroxylamino group -N(OH)-R₇ in which R₇ represents C1-C₄ alkanoyl and Rj and R₂ have the above meanings, and salts and metal ion complexes thereof.

In particular, the invention concerns compounds of the formula I in which R-. represents hydrogen, halogen, hydroxy, C_rC₄ alkoxy or C_rC₄ alkyl; R₂ represents hydroxy or esterified hydroxy which is cleavable under physiological conditions; and R₃ together with the carbonyl group to which it is attached, represents esterified carboxy which is cleavable under physiological conditions, and salts thereof.

In particular, the invention concerns also compounds of the formula I in which R_λ represents hydrogen, halogen, hydroxy, C_rC₄ alkoxy or C_rC₄ alkyl; R₂ represents hydroxy or esterified hydroxy which is cleavable under physiological conditions; and R₃ represents a group of the partial formula -N(R₄,R₅) in which R₄ represents hydroxy or esterified hydroxy which is cleavable under physiological conditions, and R₅ represents hydrogen, C₁-C₄ alkyl or a group -X-R₆ in which X is C₂-C₁₂ alkylen and R represents a hydroxylamino group -N(OH)-R₇ in which R₇ represents -C₄ alkanoyl or in which X is oxaalkylen having 4-12 chain members and

alkyl; and salts and metal ion complexes thereof.

Especially preferred are compounds of the formula I in which R_l represents hydrogen, R₂ represents hydroxy, and R₃ together with the carbonyl group to which it is attached, represents esterified carboxy which is cleavable under physiological conditions, and pharmaceutically acceptable salts thereof.

Especially preferred are likewise compounds of the formula I in which R_j represents hydrogen, R₂ represents hydroxy, and R₃ represents a group of the partial formula -N(R₄,R₅) in which R₄ represents hydroxy and R₅ represents C1-C₄ alkyl, and pharmaceutically acceptable salts thereof.

The invention relates especially to the compounds of the formula (I) mentioned in the examples, and to salts, especially pharmaceutically acceptable salts, thereof.

The compounds of the formula (I) according to the invention and salts thereof can be manufactured by chemical synthesis according to processes known per se. They are manufactured, for example,

a) by reacting a picolinic acid derivative of the formula (II)

in which R-^ represents hydrogen, halogen, hydroxy, protected hydroxy, C_rC₄ alkoxy or -C₄ alkyl; R₂ represents hydroxy, esterified or protected hydroxy and Y represents carboxy or a reactive functional derivative of a carboxy group, with a cysteine derivative of the formula (III)

in which R₃ represents etherified hydroxy or a group of the partial formula -N(R₄,R₅) in which R₄ and R₅ independently from each other represent hydrogen or C1-C₄ alkyl or in which R₄ represents hydroxy, esterified or protected hydroxy and R₅ represents hydrogen, C_!-C alkyl or a group -X-R(. in which X is C₂-C₁₂ alkylen or oxaalkylen having 4-12 chain members and R represents C C₂ alkyl or a hydroxylamino group -N(OH)-R₇ in which R₇ represents C_rC alkanoyl and the hydroxy group is optionally protected, or with a reactive functional derivative of said cysteine derivative (III), or, b) in a compound of the formula (IV)

in which Rt and R₂ have the above meanings, by converting the radical Z which is a carboxy group or a reactive functional derivative thereof, into a group of the partial formula -COR₃ in which R₃ has the above meanings, and, if required, splitting off optionally present protecting groups, and/or, if desired, in a resulting compound of the formula (I) in which R₁ and/or R₂ and/or R₄ represent hydroxy, converting said hydroxy into esterified hydroxy, and/or, if desired, converting an obtainable compound of the formula (I) in which R₃ represents etherified hydroxy into a compound of the formula (I) in which R₃ represents a group of the partial formula -N(R ,R₅), and/or converting an obtainable free compound of the formula (I) into a salt thereof.

The process is preferably carried out with optically pure (S) conformers of the compounds of the formula (III) and (IV).

Alkali and alkaline earth metal salts of 2-(3'hydroxypyrid-2'-yl)-2-thiazoline- -4(S)-carboxylic acid and especially the sodium salt arc novel compounds and can be prepared starting from the acid according to processes known per se, for example by reacting D-cysteine with 3-hydroxy-2-picolinonitrile and neutralization of the resulting optically pure acid with the corresponding anorganic base. These salts, especially the optically pure (S) contormers are valuable starting material for the production of the compounds of the formula (I) and exhibit valuable therapeutical properties. Free hydroxy groups present in the compounds of the formula (II), (IE) and (IV) are optionally protected by conventional protecting groups. Such protecting groups protect the hydroxy groups from undesired condensation reactions, substitution reactions and the like. The protecting groups can be introduced and removed readily, i.e. without undesirable secondary reactions taking place, for example by solvolysis or reduction, in a manner known per se. Protecting groups and the methods by which they are introduced and split off are described, for example in "Protective Groups in Organic Chemistry", Plenum Press, London, New York 1973, and also in "Methoden der organischen Chemie", Houben-Weyl, 4th edition, vol. 15/1, Georg Thieme Verlag, Stuttgart 1974.

Suitable hydroxy-protecting groups are, for example, acyl radicals, such as lower alkanoyl optionally substituted, for example by halogen, such as 2,2-dichloroacetyl, or acyl radicals of carbonic acid semiesters, especially tert.-butoxycarbonyl, optionally substituted benzyl- oxycarbonyl, for example 4-nitrobenzyloxycarbonyl, or diphenylmethoxycarbonyl, alkenyloxycarbonyl, for example allyloxycarbonyl, or 2-halo-lower alkoxycarbonyl, such as 2,2,2-trichloroethoxycarbonyl, also trityl or formyl, or organic silyl radicals, also etherifying groups that can readily be split off, such as tert. -lower alkyl, for example tert.-butyl, or 2-oxa- or 2-thia-cycloalkyl having 5 or 6 ring atoms, for example tetrahydrofuryl or 2-tetrahydropyranyl or corresponding thia analogues, and also optionally substituted 1-phenyl-lower alkyl, such as optionally substituted benzyl or diphenylmethyl, there coming into consideration as substituents of the phenyl radicals, for example, halogen, such as chlorine, lower alkoxy, such as methoxy, and/or nitro.

A reactive functional derivative of a carboxy group (Y or Z in the compounds of the formula (II) or (IV)) is, for example, an acid anhydride, an activated ester or an activated amide, furthermore, as radical Y, also cyano, a group of the formula -C(OR_a)₃ or -C(=NH)-R_a in which R^ is lower alkyl. Corresponding derivatives are well-known in the art.

Of the anhydrides, the mixed anhydrides are especially suitable. Mixed anhydrides are, for example, those with inorganic acids, such as hydrohalic acids, i.e. the corresponding acid halides, for example chlorides or bromides, also with hydrazoic acid, i.e. the corresponding acid azides. Further mixed anhydrides are, for example, those with organic carboxylic acids, such as with lower alkanecarboxylic acids optionally substituted, for example by halogen, such as fluorine or chlorine, for example pivalic acid or trichloroacetic acid, or with semiesters, especially lower alkyl semiesters of carbonic acid, such as the ethyl or isobutyl semiester of carbonic acid, or with organic, especially aliphatic or aromatic, sulphonic acids, for example p-toluenesulfonic acid. Of the activated esters, there may be mentioned, for example: esters with vinylogous alcohols (i.e. enols, such as vinylogous lower alkenols), or iminomethyl ester halides, such as dimethylimino- methyl ester chloride (prepared from the carboxylic acid and, for example, dimethyl- (l-chloroethylidene)-iminium chloride of the formula (CH₃)₂N^Θ=C(C1)CH₃C1^Θ, which can be obtained, for example, from N,N-dimethylacetamide and phosgene), or aryl esters, such as preferably suitable substituted phenyl esters, for example phenyl esters substituted by halogen, such as chlorine, and/or by nitro, for example 4-nitrophenyl ester, 2,3- dinitrophenyl ester or 2,3,4,5,6-pentachlorophenyl ester, N-hetero-aromatic esters, such as N-benztriazole esters, for example 1-benztriazole ester, or N-diacylimino esters, such as N-succinylimino or N-phthalylimino ester. Suitable activated amides are, for example, imidazolides, also 1,2,4-triazolides, tetrazolides or 1,2,4-oxadiazolinonides.

The activation of a carboxy group Y or Z in the compounds of the formula II or IN can also be effected in situ.

A reactive functional derivative of a cysteine of the formula (HI) is a compound in which the amino and/or mercapto group is activated for the reaction with the carboxy group of a compound of the formula (II), that is to say is present in nucleophilic form. The amino group is activated, for example, by reaction with a phosphite.

The reaction of the compound of the formula (II) in which Y represents carboxy with the cysteine derivative of the formula (111) according to process a) is preferably carried out in the presence of a suitable condensation agent or under dehydrating conditions, for example while removing the water of reaction by azeotropic distillation. Customary condensation agents are, for example carbodϋmides, for example Ν,Ν'-diethyl-, N,N'-di- propyl-, N,N'-dicyclohexyl- or N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide, suitable carbonyl compounds, for example carbonyldiimidazole, or 1,2-oxazolium compounds, for example 2-ethyl-5 -phenyl- 1,2-oxazolium 3'-sulphonate or 2-tert.-butyl- 5-methyl-isoxazolium perchlorate, or a suitable acylamino compound, for example 2-ethoxy-l -ethoxycarbonyl- 1,2-dihydroquinoline, furthermore diphenylphosphoryl azide. The condensation reaction is carried out preferably in an anhydrous reaction medium, preferably in the presence of a solvent or diluent, for example methylene chloride, benzene or tetrahydrofuran and, if necessary, while cooling or heating, for example at ambient temperature or at slightly elevated temperature, and/or in an inert gas atmosphere. If a compound of the formula (II) in which Y represents an acid anhydride derivative of a carboxy group is applied the reaction is performed under essentially the same conditions in the presence of a basic agent such as the sodium or potassium salt of carbonic acid, or a tertiary amino compound such as a tri-Cj-C₄-alkyl amine, for example triethylamine, or a pyridine base such as pyridine or quinoline.

A preferred form of process a) according to the invention is the reaction of a compound of the formula (II) in which Y represents cyano with a cysteine derivative of the formula (UI). The reaction is carried out in an inert solvent such as an aqueous solvent at ambient temperature or, preferably, at slightly elevated temperature, for example at about 50° to 80°C, and preferably under an inert gas atmosphere

A preferred form of process b) according to the invention is the reaction of a compound of the formula (IN) in which Z represents carboxy or a reactive functional derivative thereof, for example an activated ester, with an alkanol of the formula R₃'-OH or with a compound which is convertible into an alkanol of the formula R₃'-OH (R₃O corresponds to etherified hydroxy R₃ in the resulting compound of the formula (I)), for example a corresponding ketal of a di-Cx-C^-alkyl keton such as acetone, for the preparation of a methyl ester especially 2,2-dimethoxy- or diethoxy-propane, or with an amine of the formula HΝ(R₄,R₅). In the alternative, for the synthesis of a compound of the formula (I) in which R₃ is an etherified hydroxy group, Z in a tarting compound of the formula (IV) may also be a carboxy group in the salt form, such as the group -COOMe in which Me is, for example, a univalent cation of an alkali metal such as Na⁺ or K⁺. Such salt is reacted with a compound of the formula Rj'-Z' in which R₃' has the above meaning and Z' represents a reactive functional derivative of a hydroxy group. A reactive functional derivative of a hydroxy group is, for example, an ester with an inorganic acid, such as hydrohalic acid, i.e. the corresponding halide, for example chloride or bromide, or with an organic, especially aliphatic or aromatic, sulfonic acids, for example methanesulfonic acid, p-toluenesulfonic acid or m-bromobenzenesulfonic acid. It is also possible to use diazo-C_j-C₄-alkanes, especially diazomethane, which upon reaction with a compound of the formula (IV) in which Z represents carboxy yields the corresponding C₁-C₄-alkyl ester.

For example, for the preparation of a compound of the formula (I) in which R₃ represents etherified hydroxy according to process b) a carboxylic acid compound of the formula (IV) (Z represents carboxy) is reacted with an alcohol of the formula R₃'-OH in an inert solvent in the presence of a condensation agent such as a carbodϋmide or an acidic agent such as an aromatic sulfonic acid as defined above while heating or the reaction is done with the formed water being removed from the reaction mixture by azeotropic distillation. In the alternative it is also possible to react in an inert solvent while cooling, for example at about 0°C, a carboxylic acid compound of the formula (IN) (Z represents carboxy) with a

especially diazomethane, to obtain a compound of the formula (I) in which R₃ represents -C₄ alkoxy, especially methoxy.

For the preparation of a compound of the formula (I) in which R₃ represents a group of the formula -Ν(R₄,R₅), for example, a compound of the formula (IN) in which Z is a reactive functional derivative of a carboxy group, is reacted with an amine of the formula HΝ(R ,R₅). A prefeιτed functional derivative of a carboxy group according to the invention is the N-succinylimino ester. The reaction is performed in an inert solvent such as an aprotic solvent for example dimethylformamide, dimethylsulfoxide or dioxane or an C_rC alkanol such as methanol, at ambient temperature or while cooling, for example at about 0°C.

In a resulting compound of the formula (I) in which one or more functional (hydroxy) groups are protected, the latter can be freed, optionally in stages or simultaneously, in a manner known per se, by means of solvolysis, especially hydrolysis or acidolysis, or in some cases also by means of careful reduction. Silyl protecting groups are advantageously split off with fluorides, for example tetraethylammonium fluoride.

The compounds of the formula (I) obtainable according to the invention can be converted in a manner known per se into other compounds of the formula (I).

For example, in a compound of the formula (I) in which R₂ and/or R₄ represent hydroxy the hydroxy group(s) can be converted into (a) esterified hydroxy group(s). The conversion can be performed, for example, by reacting a salt of a compound of the formula (I), for example the sodium salt or disodium salt, of the phenolic hydroxy group R₂ and/or of the hydroxylamine hydroxy group R with an acylating agent of the formula Ac_j-Z' in which Ac_x is the acylating group which together with the hydroxy oxygen atom forms the esterified hydroxy group R₂ and or R₄, and Z' represents a reactive functional derivative of a hydroxy group as defined above. Furthermore, an obtainable compound of the formula (I) in which R₃ represents etherified hydroxy can be converted into a compound of the formula (I) in which R₃ represents a group of the partial formula -N(R ,R₅). The reaction is performed essentially as described under process b) using a compound of the formula (I) in which R₃ represents etherified hydroxy as starting material in place of a corresponding compound of the formula (IN) in which Z is a reactive functional derivative of a carboxy group, and reacting it with an amine of the formula HΝ(R₄,R₅).

Salts of compounds of the formula (I) can be manufactured in a manner known per se. Thus, salts of compounds of the formula (I) having acidic groups (for example R₄ represents hydroxy) can be formed, for example, by treating with metal compounds, such as alkali metal salts of suitable organic carboxylic acids, for example the sodium salt of α-ethylcaproic acid, or with inorganic alkali metal or alkaline earth metal salts, for example sodium bicarbonate, or with ammonia or a suitable organic amine, preferably stoichiometric quantities or only a small excess of the salt-forming agent being used. Acid addition salts of compounds of the formula (I) are obtained in customary manner, for example by treating with an acid or a suitable anion-exchange reagent. Internal salts of compounds of the formula (I) (zwitterionic forms) can be formed, for example, by neutralising the compounds or salts, such as acid addtion salts, to the isoelectric point, for example with weak bases, or by treating with liquid ion-exchangers.

Salts can be converted in customary manner into the free compounds: metal and ammonium salts can be converted into the free compounds, for example, by treating with suitable acids, and acid addition salts, for example, by treating with a suitable basic agent.

The starting materials, especially those of formula (II) and (HI) as well as amines of the formula HN(R₄,R₅), are available commercially and/or known or can be manufactured by known processes. Starting compounds of the formula (IV) in their racemic form are known from U.S. Patent No. 4,406,905 or can be prepared in an analogous manner as described therein. The racemates can be split in a manner known per se, for example after conversation of the optical antipodes into diastereoisomeres, for example by reaction with optically active acids or bases. Hydroxylamine compounds of the formula HN(R₄,R₅) in which R₄ represents optionally esterified or protected hydroxy and R₅ represents a group of the partial formula -X-R₆ as defined above can be manufactured in a manner known p_er se. For example, a hydroxylamine compound of the formula HN(R₄,R₅) in which R₄ represents hydroxy and R₅ represents a group -X-N(OH)-R₇ as defined above can be manufactured in the following manner:

A diprotected hydroxylamine such as N-BOC-O-benzyl hydroxylamine (compound A) is alkylated with a ω,ω'-dichloro-C₂-C₁₂-alkane in the presence of a strong base such as sodium hydride; in the resulting N-(ω-chloro-C₂-C₁₂-alkyl)-N-BOC-O-benzyl hydroxylamine the BOC protecting group is removed by treatment with trifluoroacetic acid in methylene chloride and the resulting deprotected compound is reacted with a C₁-C -alkanoyl (R₇ residue) chloride in the presence of a basic agent such as sodium hydroxide (for example in a mixed solvent water/methylene chloride) to yield the corresponding N-(C₁-C₄-alkanoyl)-N-(o)-chloro-C₂-C₁₂-alkyl)-O-benzyl hydroxylamine (compound B); the above compound A is reacted with compound B in the presence of a strong basic agent such as sodium hydride and after reductive (H₂ in, for example methanol) removal of the hydroxy protecting groups (benzyl) N-(C₁-C₄-alkanoyl)-N- [co-(N-BOC-N-hydroxy-amino)-C₂-Ci₂-alkyl]-hydoxylamine (compound C) is obtained. Compound C is treated with trifluoroacetic acid in methylene chloride in order to remove the BOC protecting group resulting in the desired starting compound N-(C₁-C₄-alkanoyl)- N-[ω-(N-hydroxy-amino)-C₂-Ci₂-alkyl]-hydoxylamine [HN(R ,R₅) in which R₄ represents hydroxy and R₅ represents a group -X-N(OH)-R in which X is C^-C^-alkylen and R₇ is C₁-C₄-alkanoyl].

The pharmacologically acceptable compounds of the present invention can be used, for example, for the manufacture of pharmaceutical compositions which contain an effective amount of the active substance together or in admixture with inorganic or organic, solid or liquid, pharmaceutically acceptable carriers.

The pharmaceutical compositions according to the invention are those which are suitable for enteral, such as oral, administration and for parenteral, such as subcutaneous, administration to warm-blooded animals, especially humans, and which contain the pharmacological active substance on its own or together with a pharmaceutically acceptable carrier. The dosage of the active substance depends on the species of warm-blooded animal and on the age and individual condition, the illness to be treated and also on the mode of administration.

The novel pharmaceutical preparations contain from approximately 10 % to approximately 95 %, preferably from approximately 20 % to approximately 90 %, of the active substance. Pharmaceutical compositions according to the invention can, for example, be in unit dose form, such as dragees, tablets, capsules, suppositories or ampoules, and contain from approximately 0.1 g to approximately 3.0 g, preferably from approximately 0.3 g to approximately 1.0 g, of the active ingredient.

The pharmaceutical compositions of the present invention are manufactured in a manner known per se, for example by means of conventional mixing, granulating, confectioning, dissolving or lyophilising processes. Pharmaceutical compositions for oral use can be obtained by combining the active substance with one or more solid carriers, if desired granulating a resulting mixture and processing the mixture or granulate, if desired or necessary after the addition of suitable adjuncts, to form tablets or dragee cores. In so doing, they can also be incorporated into plastics carriers which release the active substances or allow them to diffuse in controlled amounts.

Suitable carriers are especially fillers, such as sugars, for example lactose, saccharose, mannitol or sorbitol, cellulose preparations and/or calcium phosphates, for example tricalcium phosphate or calcium hydrogen phosphate, also binders such as starches, for example corn, wheat, rice or potato starch, gelatine, tragacanth, methylcellulose, hydroxypropylmethylcellulose, sodium carboxymethylcellulose and/or polyvinyl- pyrrolidone, and/or, if desired, disintegrators, such as the above-mentioned starches, also carboxymethyl starch, crosslinked poly vinylpyrrolidone, agar, alginic acid or a salt thereof, such as sodium alginate. Adjuncts are especially flow-regulating and lubricating agents, for example silica, talc, stearic acid or salts thereof, such as magnesium or calcium stearate, and/or polyethylene glycol. Dragee cores are provided with suitable coatings that are, if desired, resistant to gastric juice, there being used, inter alia, concentrated sugar solutions which optionally contain gum arabic, talc, poly vinylpyrrolidone, polyethylene glycol and/or titanium dioxide, lacquer solutions in suitable organic solvents or solvent mixtures or, for the manufacture of coatings that are resistant to gastric juice, solutions of suitable cellulose preparations, such as acetylcellulose phthalate or hydroxypropyl¬ methylcellulose phthalate. Colouring substances or pigments can be added to the tablets or dragee coatings, for example for the purpose of identification or for indicating different doses of active substance.

Other orally administrable pharmaceutical compositions are dry-filled capsules made of gelatin, and also soft, sealed capsules made of gelatin and a plasticiser, such as glycerol or sorbitol. The dry-filled capsules may contain the active ingredient in the form of a granulate, for example in admixture with fillers, such as corn starch, binders and/or glidants, such as talc or magnesium stearate, and optionally stabilisers. In soft capsules the active ingredient is preferably dissolved or suspended in suitable liquids or wax-like substances, such as fatty oils, paraffin oil or polyethylene glycols, it being possible also for stabilisers to be added.

Other forms of oral administration are, for example, syrups prepared in customary manner that contain the active ingredient in, for example, suspended form and in a concentration of approximately from 5 % to 20 %, preferably approximately 10 %, or in a similar concentration that provides a suitable single dose when administered, for example, in measures of 5 or 10 ml. Also suitable are, for example, powdered or liquid concentrates for preparing shakes, for example in milk. Such concentrates can also be packed in single-dose quantities.

Particularly suitable dosage forms for parcnteral administration are sterile aqueous solutions of an active ingredient in water-soluble form, for example a water-soluble salt, or sterile aqueous injection suspensions which contain substances increasing the viscosity, for example sodium carboxymethyl cellulose, sorbitol and/or dextran, and optionally stabilisers. In addition, the active ingredient, with or without adjuvants, can also be in lyophilised form and brought into solution prior to parcnteral administration by addition of suitable solvents.

The invention relates also to compositions for diagnostic purposes that contain a suitable metal complex of a compound of the formula (I) in which R_λ has the above meanings, R₂ represents hydroxy and R₃ represents a group of the formula -N(R₄,R₅) in which R represents hydroxy and R₅ has the above meanings, preferably in the form of an aqueous solution or in the form of a dry preparation.

The invention relates also to a method of treatment of pathological conditions in a mammal, especially human, which, as has been described hereinbefore, are associated with an excess of a trivalent metal cation such as aluminium or, especially, iron(III), in the body, which method comprises administering, preferably orally, a prophylactically or therapeutically effective amount of a compound of formula (I) or of a pharmaceutically acceptable salt thereof. There are used for this purpose especially the above-mentioned pharmaceutical compositions, a daily dose of from approximately 100 mg to approximately 2000 mg, preferably from approximately 300 mg to approximately 1000 mg, of a compound of the present invention being administered to a warm-blooded animal of approximately 70 kg body weight. The dosage can be administered orally in several, for example three, individual doses. For systemic, e.g. subcutaneous, administration the more water soluble salt forms of the compounds of the formula (I), e.g. the sodium salt, are preferred, for example orally, or alternatively subcutaneously.

The invention concerns especially the compounds of the formula (I), the methods for the preparation thereof and pharmaceutical compositions as described in the examples.

The following examples serve to illustrate the invention but should not be construed as a limitation thereof. Temperatures are given in degrees Centigrade.

Example 1: 2-(3'-hvdroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylic acid (optically pure, zwitterionic form)

A mixture of 30 ml each of 1 M phosphate buffers of pH 7.0 and 4.5 respectively is placed in a reaction flask and diluted with 350 ml of methanol and 250 ml of water treated in a Nanopur water purification system. The diluted buffer solution is degassed by passing a vigorous stream of argon through the solution. After addition of 20.0 g (165 mmole) of D-cysteine the temperature of the solution is raised to 35° in a heating bath under continuous agitation. As soon as the D-cysteine is almost completely dissolved a quantity of 9.91 g (82.5 mmole) of 3-hydroxy-2-picolinonitrile is added in one portion. The pH of the reaction mixture is adjusted to a value of 7.5 by the addition of 2 N sodium hydroxide solution. The almost clear solution is subsequently heated to 65-70° and stirred under argon atmosphere in order to avoid formation of cystine by oxygen. The reaction is terminated after 8 hrs. The clear solution with the pH value of 8.2 is concentrated on a rotary evaporator under reduced pressure. 300 ml of methylene chloride are added to the aqueous concentrate. The mixture is acidified to pH 2.5 by addition of 4N hydrochloric acid. The organic extract is separated and the aqueous phase is reextracted twice with small portions of methylene chloride. The combined organic extracts are washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate and evaporated to dryness. The residue is recrystallized from methanol, yielding bright yellow needles with a m.p. of 144-46°. The crystallisate still contains traces of water (0.05 mol. equiv.) after drying in the high vacuum: elemental analysis (for HgN^S • 0.05 H₂O)

optical rotation (c = 1.42 % in dioxan): 436 nm = -44.3 546 nm = -23.9° ± 0.7 578 nm = -20.2° ± 0.77589 nm (Na_D) = 19.5° ± 0.7°

Example 2: Sodium 2- (3 ' -hvdrox vp yrid-2 ' -yl)-Δ²- thiazoline-4(S )-carboxylate

16.82 g (75 mmole) of the acid as prepared in example 1 is suspended in 400 ml of deiomzed water. The pH value is slowly raised by addition of 2 N sodium hydroxide under stirring. The pH of 7.0 is reached after addition of exactly one molar equivalent (37.5 ml). The clear solution is lyophilised to yield an amorphous yellow powder.

After drying under high vacuum the sodium salt contained one molar equivalent of water: elemental analysis (for C9H₅N.1N_.O₃S • H₂O)

% calc:

optical rotation (c = 0.261 % in DSMO): 546 nm = -124.57578 nm = -101.57589 nm (Na_D) = 94.6° ± 3.8°

UV spectrum in ethanol: ^^(e) = 311 nm (9800), sh at 240 nm

Example 3: Pivaloyloxymethyl-2-(3^,-hvdroxypyrid-2^,-yl)-Δ²-thiazoline- 4(S)-carboxylate

3.36 g (15 mmole) of sodium 2-(3'-hydroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylate as prepared in example 2 is suspended in 150 ml of methylene chloride. After addition of 2.1 ml (15 mmole) of triethylamine and 3.60 ml (16.5 mmole) of iodomethylpivalate with a purity of 79 % the reaction mixture is stirred at room temperature. After 2 hrs. an additional amount of 1 ml of the iodomethylpivalate is added to the suspension. Stirring is continued during further 20 hrs. at room temperature. The reaction mixture is extracted with two 100 ml portions of phosphate buffer of pH 7.0 and an equal amount of sodium thiosulfate solution. The organic phase is evaporated to dryness. The residue (7.25 g) is redissolved in methanol. The dark colored solution is treated with charcoal. The solvent is evaporated and the oily residue is taken up in diethyl ether. A small precipitate of starting material (0.4 g) is removed by filtration. The oily residue (6.54 g) obtained after evaporation of the solvent is redissolved in a small amount of methylene chloride and transferred on a chromatographic column containing 160 g of silicagel. The pure ester is eluted with 400 ml of methylene chloride containing 10 % of methanol. The fractions containing the pure product are combined and concentrated in vacuo yielding the desired product in the form of a yellow oil.

IR - spectrum in methylene chloride : main absorption bands at 1758 (very strong band), 1592, 1451, 1302, 1183, 1110 and 991 cm^"1.

UV-spectrum : ^e) = 311 nm (9180), 202 nm (26'400) sh at 239 nm z in. = 256 nm (l'015)

optical rotation (c = 2.59 % in ethanol) : 546 nm = -4,5° ± 0.4 /578 nm = -4.2° ± 0.4 %/589 nm = -3.6° ± 0.4%

Example 4: Succinimido -2-(3^,-hvdroxypyrid-2'-yl)-A²-thiazoline-4(S)-carboxylate

112.1 mg (0,5 mmole) of 2-(3'-hydroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylic acid and 65.3 mg (0.55 mmole) N-hydroxysuccinimide are placed in a 3-neck reaction vessel and purged with nitrogen gas. The reactants are dissolved in 6 ml of dry tetrahydrofurane and cooled to 0° in an ice-bath. Under stirring a solution of 113.5 mg (0.55 mmole) of N, N'-dicyclohexyl-carbodiimide in 4 ml of dry tetrahydrofurane is slowly added and stirring continued for 30 min. at 0°. The resulting suspension is kept at room temperature overnight. The solid precipitate of N,N'-dicyclohexyl-urea is filtered off and washed with 15 ml of ethyl acetate. The solvents are evaporated on a rotatory evaporator and the resulting solid is recrystallized from ethyl acetate. Two crops of crystals are collected and washed with ice-cold solvent. The pooled crystallizate is dried in the high vacuum.

1H-NMR (CDC-₃+DMSO-άVTMS): 8.15 (t, 1H), 7.30 (d, 2H), 5.73 (t, 1H), 3.72 (d, 2H),

(Racemic mixture)

1.0 g (3.11 mmole) of the N-hydroxysuccinimidoester prepared in the previous example is placed in a 3-neck reaction flask and dissolved in 20 ml dry degassed dimethylformamide. Under cooling to 0° a clear solution of N-methyl-hydroxylamine in DMF is dropped and stirring continued at 0° during 3.5 hr. The latter solution is prepared before from 2.6 g (31.1 mmole) of N-methyl hydroxylamine hydrochloride in 20 ml of abs. dimethyl¬ formamide by slow addition of a solution of 3.15 g (31.1 mmole) of triethylamine in 5 ml of dimethylformamide at 0°, stirring for 30 min. and filtration of the triethylamine hydrochloride.

After completion of the reaction the solvent is evaporated under vacuum. The resulting oil is triturated with 30 ml of an aqueous saturated solution of sodium bicarbonate at 0° to get a precipitate. The mixture is extracted repeatedly with 40 ml of chloroform and the solvent is removed to give a solid crude product which is almost homogenous by thin-layer chromatography on silicagel plates developed with chloroform containing 6 % of ethanol as the solvent system.

The crude product is further purified by chromatography on 20 g of Sephadex LH-20 resin. The solid material is first dissolved in a small amount of methanol. To the concentrated solution 1.5 g of Sephadex LH-20 is added and the suspension is dried under vacuum overnight. The dried residue is applied on top of the column and elution is performed with toluene/ethanol in the ratio of 19:1. Elution of the product is monitored by chromatography on silicagel thin-layer plates. The fractions containing pure material are pooled, evaporated to dryness and recrystallized from toluene/ethanol to yield colorless needles, m.p. 158-159°. 1H-NMR (DMSO-d_fi-TMS): 8.15 (t, 1H), 7.42 (d, 2H), 5.90 (t, 1H), 5.90 (t, 1H), 3.53 (d, 1H), 3.47 (d, 1H), 3.27 ppm (s, 3H)

elemental analysis (for C₁oH₁₁N₃O₃S)

% calc: % found:

To isolate the optically pure (S) conformer either the racemate can be split in a manner known per se, for example after conversation of the optical antipodes into diastereo¬ isomeres, for example by reaction with optically active acids or bases or the optically pure form can be prepared as described below in detail.

Example 6: N-methyl-2-(3'-hvdroxypyrid-2'-yl)-Δ²-thiazoline-4(S) hydroxamic acid (optically pure, zwitterionic form)

224.2 mg (1.0 mmole) 2-(3'-hydroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylic acid and 83.5Amg (1.0 mmole) N-methyl-hydroxylamine hydrochloride are placed in a 3-neck reaction vessel and purged with nitrogen gas. The reactants are dissolved in 6 ml degassed dimethylformamide (DMF). After cooling to 0°C in an ice-bath 442.3 mg (1 mmole) of BOP-reagent [benzotriazole-1-yloxy tris(dimethylamino)phoshonium hexafluorophosphate] is added. Under stirring a solution of 129.3 mg (1.0 mmole) diisopropylethylenediamine in 4 ml DMF is slowly dripped into the above solution at 0°C. After continued stirring for 20 minutes at 0°C and overnight at room temperature the solvent is evaporated under high vacuum. The resulting residue is redissolved in 30 ml ethyl acetate and washed successively with 10 ml saturated sodium bicarbonate solution, 10 ml saturated sodium chloride, 10 ml 10 % aq. citric acid solution and again with 10 ml saturated sodium chloride solution. The organic phase is dried over anhydrous sodium sulfate, filtered and evaporated to dryness on a rotatory evaporator. The crude product is purified by column chromatography on Sephadex LH 20 using a solution of 3 % of ethanol in toluene as the eluent. The fractions containing the pure desired compound are combined and evaporated to dryness leaving 120 mg (47 % yield) of a chromatographically homogeneous yellow solid. 1H-NMR (CDCI₃ and DMSO-d₆-TMS): δ 8.15 (t,lH); 7.30 (d,2H); 5.70 (t,lH); 3.53 (dd,A2H); 3.27 (s, 3H).

elemental analysis (for C₁₀H₁₁N₃θ₃S)

Example 7: Magnesium bis r2-(3'-hvdroxypyrid-2^,-yl)-Δ²-thiazoline-4(S)- carboxylatel

11.2 g (46.23 mmole) of the acid in the form of the monohydrate is suspended in 400 ml of deionized water. Magnesium hydroxide (FLUKA, > 95 %) is added in portions under pH control over a period of 2 hr. The pH value is increased from 3.0 to 5.0 after addition of a total of 1.53 g of the magnesium hydroxide (25 mmole of > 95 % pure reagent). The clear solution is lyophilized yielding 10.7 g (98.4 %) of the desired product.

elemental analysis (for C₁₈H₁₄MgN₄O₆S₂-2.75 mole of H O)

Example 8: 2- (3 ' -h ydroxy yrid-2 ' - yl)-Δ²-thiazoline-4-h ydroxamic acid (Racemic mixture)

126.35 mg (1.8 mmole) hydroxylamine hydrochloride is placed in a 3-neck reaction vessel purged with dry nitrogen. The reagent is dissolved in 4 ml dry methanol under stirring for 5 min. at 0°. To the clear solution 1.8 ml 1 M sodium methoxide in dry methanol (1.8 mmole) is added slowly over a period of 5 min. and stirring is continued for 10 min. at 0°. The resulting suspension is added dropwise to a slurry prepared from 357.6 mg (1.5 mmole) of methyl-2-(3'-hydroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylate in 33 ml of dry methanol, which has been purged with nitrogen and cooled in an ice-bath. The empty glassware is washed with 2.2 ml of dry methanol. After completion of the addition the reaction mixture is stirred during 30 min. and subsequently allowed to warm up to room temperature. The turbid solution clears up and stirring is continued for one hour at room temperature. Examination by thin-layer chromatography on silicagel (solvent system chloroform/methanol 9:1) reveals only traces of the starting material. The solvent is removed in a rotatory evaporator and the yellow residue is triturated with benzene. The crude product is purified by preparative chromatography on a column containing 20 g of silicagel. The desired product is eluted with a mixture of chloroform/methanol (9:1). Fractions containing the pure product are pooled and evaporated to dryness, yielding a light yellow solid.

m.p. 163-165°

*H-NMR (DMSO-c^): 8.15 (t, 1H), 7.43 (d, 2H), 5.27 (t, 1H), 3.52 ppm (d, 2H)

elemental analysis (for ₃H]i ₁ N₃O5S )

% calc. : C 48.60 % found :

H 3.45 N 13.08

To isolate the optically pure (S) conformer either the racemate can be split in a manner known per se, for example after conversation of the optical antipodes into diastereo¬ isomeres, for example by reaction with optically active acids or bases or the optically pure form can be prepared as described below in detail. Example 9: N-r5-(N-acetyl-N-hvdroxy-amino)-pentvI1-2-(3'-hvdroxypyrid-2'-yl)-A²-

-thiazoline-4(S)-hydroxamic acid

(a) N-(tert-Butoxycarbonyl)-O-benzylhydroxylamine (4 g, 18 mmol) is dissolved in DMF (60 ml). NaH (80 %, 0,591 g, 19,7 mmol) is added in portions at 0°, and followed by stirring at 0° for 30 min. A solution of 1,5-dichloropentane (12.8 g, 89.6 mmol) in DMF (20 ml) is slowly dripped in, and the solution is stirred at 0° for 20 min. and 70-80° overnight. The solvent is removed under high vacuum, and the residue is quenched with water (50 ml) at 0°. The aqueous layer is extracted with CH₂C1₂ (4 x 40 ml), and the organic fractions are combined and dried over Na₂SO₄. Drying agent is filtered, and the solvent is removed. The crude oil is purified by silica gel column chromatography using 1:29:70 EtOAc:CHCl₃:hexanes as eluant, to give N-(5-chloropentyl)-N-(tert- butoxycarbonyl)-O-benzylhydroxylamine as an oil.

1H-NMR (CDC1₃): δ 1.47 (s, 9 H), 1.30-1.90 (m, 6 H), 3.40 (t,2 H), 3.47 (t, 2 H), 4.80 (s, 2 H), 7.30 (s, 5 H). Anal, calcd. for C₁₇H₂₆ClNO₃ (%): C 62.28; H 7.99; N 4.27. Found: C 62.39; H 7.97; N 4.32.

(b) Trifluoroacetic acid (10 ml) is slowly dripped into a solution of N-(5-chloropentyl)-N- (tert-butoxycarbonyl)-O-benzylhydroxylamine (3.00 g, 9.15 mmol) in CH₂C1₂ (100 ml), which has been cooled to 0°. The reactants are stirred at 0° for 20 min and RT for 15 min. The volatiles are removed on a rotary evaporator, saturcd NaHCO₃ (60 ml) is added and product extracted with CH₂C1₂ (4 x 50 ml). Combined organic extracts are dried over Na₂SO , filtered, and the solvent is removed. The resulting oil is passed through a short silica gel column, eluting with CH₂C1₂, providing N-(5-chloropentyl)-O-benzylhydroxyl- amine as an oil.

*H-NMR (CDCI₃): δ 1.33-1.90 (m, 6 H), 2.87 (t,2 H), 3.43 (t, 2 H), 4.30 (br s, 1 H), 4.60 (s, 2 H), 7.18 (s, 5 H). Anal, calcd. for C₁₂H₁₈ClNO (%): C 63.29; H 7.97; N 6.15. Found: C 63.38; H 8.03; N 6.13.

(c) 1 N NaOH (25 ml) is added to a solution of N-(5-chloropentyl)-O-benzylhydroxyl- amine (2.13 g, 9.35 mmol) in CH₂C1₂ (35 ml), which has been cooled to 0°. Acetyl chloride (1.123 g, 14.02 mmol) in CH₂C1₂ (15 ml) is added dropwise at 0° to the biphasic mixture, which is efficiently stirred for 20 min at 0° and overnight at RT. The layers are separated, and the aqueous phase is further extracted with CH₂C1₂ (3 x 50 ml). The combined organic fractions are washed with brine (100 ml), dried over Na₂SO₄, and concentrated. Purification on silica gel chromatography using 80 % hexanes/EtOAc as an eluant produces N-acetyl-N-(5-chloropentyl)-O-benzylhydroxylamine as an oil.

*H-NMR (CDC1₃): δ 1.33-1.90 (m, 6 H), 2.07 (s, 3 H), 3.48 (t,2 H), 3.60 (t, 2 H), 4.80 (s, 2 H), 7.33 (s, 5 H). Anal, calcd. for C₁₄H₂₀C1NO₂ (%): C 62.33; H 7.47; N 5.19. Found: C 62.12; H 7.43; N 5.11.

(d) NaH (80 %,• 0.323 g, 10,8 mmol) is added in portions to a solution of N-(tert-butoxy- carbonyl)-O-benzylhydroxylamine (2.19 g, 9,79 mmol) in DMF (45 ml) at 0°. The mixture is stirred at 0° for 20 min, followed by cautious addition of a solution of N-acetyl-N-(5- chloropentyl)-O-benzylhydroxylamine (2.4 g, 8.9 mmol) in DMF (15 ml). Crude product is purified by silica gel column chromatography using 6:2:1 hexanes/EtOAc/CHCl₃ as eluant, to generate N-acetyl-N-[5-(N-BOC-N-benzyloxyamino)-pentyl]-O-benzyl- hydroxylamine as an oil.

*H-NMR (CDCI₃): δ 1.23-1.80 (m, 6 H), 1,47 (s, 9 H), 2.03 (s, 3 H), 3.36 (t, 2 H), 3.57 (t, 2 H), 4.76 (s, 2 H), 4.78 (s, 2 H), 7.30 (s, 5 H). Anal, calcd. for C^gN^ (%): C 68.40; H 7.95; N 6.14. Found: C 68.20; H 7.94; N 6.10.

(e) 10 % Pd-C (0.2 g) is added under nitrogen to a solution of N-acetyl-N-[5-(N-BOC-N- benzyloxyamino)-pentyl]-O-benzylhydroxylamine (1.020 g), 2.234 mmol) in distilled CH₃OH (80 ml). Hydrogenation is carried out at 1 arm for 2 h. Catalyst is filtred off and washed with CH₃OH. Solvent is removed, and the crude oil is purified by Sephadex LH-20 column chromatography using 4 % EtOH/toluene as an eluant, to give N-acetyl- N-[5-(N-BOC-N-hydroxyamino)-pentyl]-hydroxylamine as an oil.

*H-NMR (CD₃OD): δ 1.20-1.83 (m, 6 H), 1,46 (s, 9 H), 2.07 (s, 3 H), 3.35-3.70 (m, 4 H). Anal, calcd. for C₁₂H₂₄N₂O₅ (%): C 52.16; H 8.75; N 10.14. Found: C 52.07; H 8.72; N 10.05.

(f) Trifluoroacetic acid (6 ml) is slowly dripped into a solution of N-acetyl-N-[5-(N- BOC-N-hydroxyamino)-pentyl]-hydroxylamine (540 mg, 1.95 mmol) in CH₂C1₂ (20 ml) at 0°. Reactants are stirred at 0° for 20 min and RT for 15 min. The volatiles are removed on a rotary evaporator, dry benzene is added and evaporated a few times, and the resulting oil is dried in vacuo to provide N-acetyl-N-(5-hydroxyamino-pentyl)-hydroxylamine (as the trifluoroacetate) as an oil.

^-NMR (CD₃OD): δ 1.23-1.87 (m, 6 H), 2.07 (s, 9 H), 3.17 (t, 2 H), 3.60 (t, 2 H).

(g) The N-hydroxysuccinimide ester of example 4 (603.3 mg, 1.878 mmol) is added to a solution of N-acetyl-N-(5-hydroxyamino-pentyl)-hydroxylamine trifluoroacetate (492,4 mg, 1.878 mmol) in THF (40 ml) at 0°. Next a solution of triethylamine (412.6 mg, 4.078 mmol) in THF (20 ml) is slowly added, and the solution is stirred at RT for 6 h. Solvent is removed, and distilled water (30 ml) is added to the light yellow oil, followed by extraction with CHCI₃ (3 x 50 ml). Solvent removal, as usual, and purification an a Sephadex LH-20 column using 4 % EtOH/toluene as eluant gives N-[5-(N-acetyl-N- hydroxy-amino)-pentyl]-2-(3'-hydroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-hydroxamic acid as a thick oil.

-NMR (CD₃OD): δ 1.30-1.90 (m, 6 H), 2.05 (s, 3 H), 3.40-3.80 (m, 6 H), 5.93 (t, 1 H), 7.30 (d, 2 H), 8.05 (t, 1 H).

Example 10: Methyl 2-(3-'hvdroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylate 33.6 g (0.15mole) of 2-(3-'hydroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylic acid as prepared in example Al is suspended in 1.2 1 of methylene chloride. After addition of 184 ml (1.5 mole) of 2.2-dimethoxypropane ("acetone dimethylacetal", Fluka, purum) and of 34.2 g (0.18 mole) of p-toluenesulfonic acid monohydrate, (Merck, p.a.) the reaction mixture is stirred at room temperature during a period of 6 hr. The reaction mixture is extracted with three portions of 300 ml each of 1 -molar phosphate buffer pH 7.0. The organic phase is dried over anhydrous sodium sulfate and evaporated to dryness in vacuo. The residue is dissolved in 300 ml of diethyl ether and stored in the refrigerator before filtration. The slightly yellow colored crystals are filtered, washed with cold diethyl ether and dried in vacuo (yield: 32.76 g, 91,7 A%; m.p. 55-56 °C):

elemental analysis (for C₁₀H₁₀N₂O₃S • 0.05 H₂O)

% calc: C 50.41 % found: C 50.48

H 4.23 H 4.28

N 11.76 N 11.67

S 13.46 S 13.34 optical rotation (c = 2.0 % in dioxane): 546 nm = -15.47578 nm = -13.37589 nm (Na_D) = -12.6° IR and 1H-NMR spectra are compatible with the proposed structure.

Example 11: Ethyl 2-(3-^,hvdroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylate

A suspension of 33.6 g (0.15 mole) of the acid as prepared in example 1 in 1 1 of methylene chloride is stirred with 28.5 g (0.15 mole) of p-toluenesulfonic acid monohydrate and 120 ml (7.2 mole) of triethyl orthoformiate (Merck, p. synth.) at 4 °C during a period of 72 hr. The reaction mixture is extracted as in the previous example 9. The solvent is removed in vacuo and the dried residue (37.8 g) is crystallized from a 1:1 mixture of diethyl ether and heptane. After filtration of a first crop of crystals (21.14 g, m.p. 42-43 °C) a second crop of 14.07 g of a product with a purity of >95 % is obtained by concentration of the mother liquors (total yield: 35.21 g, 93 %). A sample of the vacuum-dried first crop of crystals gives the following analytical results: elemental analysis (for C_πH₁₂N₂θ₃S • 0.05 H₂O)

% calc.

optical rotation (c = 2 % in dioxane):

436 nm = -54.17546 nm = -31.1 ±0.5° /578 nm = -27.07589 nm (Na_D) = -25.9 ±0.5°

Example 12: N-f5 "-(N-hydroxy-N-acetyD-pentyll-

2-(3'-hvdroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-hydroxamic acid

80.0 mg (0.404 mmole) 5-(N-hydroxy-N-acetyl)-pentylamine hydrochlorid and 90.58 mg (0.404 mmole) 2-(3'-hydroxypyrid-2'yl)-Δ²-thiazoline-4(S) carbocylic acid are dissolved in 8 ml of degassed dimethylformamid (DMF). After cooling to 0°C 178.7 mg (0.404 mole) of benzotriazol-1-yloxy tris(dismethylamino)-phosphonium hexafluorophosphate is added to the solution. After slowly adding a solution of N,N'-diisopropylidendiamine in 2 ml DMF, the reaction mixture is stirred for 15 minutes at 0°C and over night at room temperature. The solvent is removed at reduced pressure (high vacuum) and the residue taken up in 40 ml of ethyl acetate. The organic phase is subsequently washed with 10 ml of saturated sodium bicarbonate solution, 10 ml of saturated saline, 10 ml of 10 % aqueous citric acid and again with 10 ml of saturated saline. The organic phase is dried over anhydrous sodium sulfate, filtered and evaporated to dryness in a rotatory evaporator. The oily residue is purified by column chromatography on Sephadex LH-20 using 4% ethanol in toluene as the eluent. The fractions giving a single spot on TLC are combined and evaporated to dryness, leaving 93 mg (60 %) of pure title compound as a yellow colored oil.

^-NMR (CD₃OD, δ TMS): 8.06 (t, 1H); Z33 (d, 2H); 3.40 - 3.80 (m, 6H); 2.06 (s, 3H): 1.30 - 1.90 (m, 6H)

optical rotation (c = 9.85 % in methanol):

589 nm = (Na_D, 25°C) = 16.7^C

Example 13: Pharmaceutical composition for oral administration

1000 gelatine capsules each containing 250 mg of active ingredient are manufactured as follows:

Composition:

250 g N-methyl-2- (3 ' -hydroxypyrid-2 ' -yl)-Δ²-thiazoline-4(S )-hydroxamic acid

36 g talc

24 g wheat starch

16 g magnesium stearate

4 g lactose

The pulverulent substances are forced through a sieve having a mesh width of 0.6 mm and mixed thoroughly to yield a total of 330 g. 1000 gelatine capsules are each filled with 330 mg of this mixture using a capsule filling machine.

Claims

What we claim is:

1. A compound of the formula (I)

in which R_l represents hydrogen, halogen, hydroxy, C_-C alkoxy or -C₄ alkyl; R₂ represents hydroxy or esterified hydroxy; and R₃ represents etherified hydroxy or a group of the partial formula -N(R₄,R₅) in which R₄ and R₅ independently from each other represent hydrogen or C_-C₄ alkyl or in which R₄ represents hydroxy or esterified hydroxy and R₅ represents hydrogen, -C₄ alkyl or a group -X-Rg in which X is C_-C₁₂ alkylen or oxaalkylen having 4-12 chain members and Rg represents

alkyl or a hydroxylamino group -N(OH)-R₇ in which R₇ represents -C₄ alkanoyl; and salts thereof.

2. A compound of the formula (I) according to claim 1 in which

(a) Ri represents hydrogen, halogen, hydroxy, Cj-0₄ alkoxy or C_j-0₄ alkyl; R₂ represents hydroxy or esterified hydroxy; and

R3 represents, together with the carbonyl group to which it is attached, an esterified carboxyl group that can be cleaved under physiological conditions or a group of the partial formula -N(R ,R5) in which R₄ and R5 independently from each other represent hydrogen or -C₄ alkyl or in which R₄ represents hydroxy or esterified hydroxy and R₅ represents hydrogen, C_-C alkyl or a group -X-R₆ in which X is C₂-C₁₂ alkylen or oxaalkylen having 4-12 chain members and R₆ represents -C^ alkyl or a hydroxylamino group -N(OH)-R₇ in which R₇ represents C_rC₄ alkanoyl; or

(b) R_ represents hydrogen, halogen, hydroxy, C_-C₄ alkoxy or C_-C₄ alkyl; R represents esterified hydroxy; and

R₃ represents -C₄ alkoxy; or

(c) R_ represents halogen, hydroxy or -C₄ alkoxy; R₂ represents hydroxy; and

R₃ represents C_rC alkoxy; and salts thereof.

3. A compound of the formula (I) according to any one of claims 1 to 2 in which R_ represents hydrogen, halogen, hydroxy, C_rC₄ alkoxy or C C₄ alkyl; R₂ represents hydroxy or esterified hydroxy; and R₃ represents etherified hydroxy or a group of the partial formula -N(R₄,R5) in which R₄ and R₅ independently from each other represent hydrogen or -C₄ alkyl, and salts thereof.

4. A compound of the formula (I) according to any one of claims 1 to 2 in which R_j represents hydrogen, halogen, hydroxy, Cj-C₄ alkoxy or -C₄ alkyl; R₂ represents hydroxy or esterified hydroxy; and R₃ represents a group of the partial formula -N(R₄,R₅) in which R₄ represents hydroxy or esterified hydroxy and R₅ represents hydrogen, C_j-C₄ alkyl or a group -X-Rg in which X is C₂-C₁ alkylen or oxaalkylen having 4-12 chain members and R^ represents C C₂ alkyl or a hydroxylamino group -N(OH)-R in which R represents Cj-C₄ alkanoyl, and salts thereof.

5. A compound of the formula (I) according to any one of claims 1 to 2 in which R- represents hydrogen, halogen, hydroxy, C_rC₄ alkoxy or C_rC₄ alkyl; R₂ represents hydroxy or esterified hydroxy which is cleavable under physiological conditions; and R₃ together with the carbonyl group to which it is attached, represents esterified carboxy which is cleavable under physiological conditions, and salts thereof.

6. A compound of the formula (I) according to any one of claims 1 to 2 in which R_ represents hydrogen, halogen, hydroxy, C C₄ alkoxy or C_-C alkyl; R₂ represents hydroxy or esterified hydroxy which is cleavable under physiological conditions; and R₃ represents a group of the partial formula -N(R₄,R₅) in which R₄ represents hydroxy or esterified hydroxy which is cleavable under physiological conditions, and R₅ represents hydrogen, C_-C₄ alkyl or a group -X-R₆ in which X is C₂-C₁₂ alkylen and R represents a hydroxylamino group -N(OH)-R₇ in which R₇ represents C_-C₄ alkanoyl or in which X is oxaalkylen having 4-12 chain members and R_$ represents Cj-C-₂ alkyl; and salts thereof.

7. A compound of the formula (I) according to any one of claims 1 to 2 in which R_ represents hydrogen, R₂ represents hydroxy, and R₃ together with the carbonyl group to which it is attached, represents esterified carboxy which is cleavable under physiological conditions, and pharmaceutically acceptable salts thereof.

8. A compound of the formula (I) according to any one of claims 1 to 2 in which R_ represents hydrogen, R₂ represents hydroxy, and R₃ represents a group of the partial formula -N(R ,R₅) in which R₄ represents hydroxy and R₅ represents C_rC₄ alkyl, and pharmaceutically acceptable salts thereof.

9. A compound according to claim 1 selected from the group consisting of Pivaloyloxymethyl-2-(3'-hydroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-carboxylate; N-methyl-2-(3'-hydroxypyrid-2'-yl)-Δ²-thiazoline-4 (S)-hydroxamic acid and 2-(3'-hydroxypyrid-2'-yl)-Δ²-thiazoline-4(S)-hydroxamic acid.

10. An optically pure compound of the formula (I) according to any one of claims 1 to 9.

11. An alkali or an alkaline earth metal salts of 2-(3'hydroxypyrid-2'-yl)-2-thiazoline- -4(S)-carboxylic acid.

12. A pharmaceutical composition comprising a therapeutically effective amount of a compound of the formula (I) according to claim 1 or a pharmaceutically acceptable salt thereof or of an alkali or an alkaline earth metal salts of 2-(3'hydroxypyrid-2'-yl)- -2-thiazoline-4(S)-carboxylic acid according to claim 11..

13. A method of treatment of pathological conditions in a mammal that are associated with an excess of trivalent metal ions in the body, comprising administering to said mammal a therapeutically effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof according to claim 1.

14. Process for the production of a compound of the formula (I) according to claim 1 comprising

a) reacting a picolinic acid derivative of the formula (II)

in which R_ reprcsents hydrogen, halogen, hydroxy, C_rC₄ alkoxy or -C₄ alkyl; R₂ represents hydroxy, esterified or protected hydroxy and Y represents carboxy or a reactive functional derivative of a carboxy group, with a cysteine derivative of the formula (III)

in which R₃ represents etherified hydroxy or a group of the partial formula -N(R₄,R₅) in which R₄ and R₅ independently from each other represent hydrogen or C_-C alkyl or in which R₄ represents hydroxy, esterified or protected hydroxy and R₅ represents hydrogen, -C₄ alkyl or a group -X-R_& in which X is C^-C^ alkylen or oxaalkylen having 4-12 chain members and R₆ represents Cj-Cj alkyl or a hydroxylamino group -N(OH)-R₇ in which R₇ represents C C₄ alkanoyl and the hydroxy group is optionally protected, or with a reactive functional derivative of said cysteine derivative (III), or,

b) in a compound of the formula (IV)

in which Rj and R₂ have the above meanings and Z is a carboxy group or a reactive functional derivative thereof, converting the radical Z into a group of the partial formula -COR₃ in which R₃ has the above meanings,

and, if required, splitting off optionally present protecting groups, and/or, if desired, in a resulting compound of the formula (I) in which R_ and/or R₂ and/or R₄ represent hydroxy, converting said hydroxy into esterified hydroxy, and/or, if desired, converting an obtainable compound of the formula (I) in which R₃ represents etherified hydroxy into a compound of the formula (I) in which R₃ represents a group of the partial formula -N(R ,R5), and/or converting an obtainable free compound of the formula (I) into a salt thereof.