CZ2007681A3 - Process for preparing reactive isothiocyanate form of DTPA benzyl derivatives - Google Patents

Abstract

The 4-isothiocyanatobenzyl derivatives of DTPA of the general formula I wherein one of the substituents Y.sup.1.n. to Y.sup.2.n. is 4-isothiocyanatobenzyl, R is NCS, wherein the second adequate substituent is hydrogen, where one of the substituents Y.sup.3.n. to Y.sup.4.n. it is methyl, the second adequate substituent being hydrogen, where Z is independently hydrogen, a monovalent, divalent or trivalent cation, is prepared from an adequate 4-aminobenzyl derivative of DTPA of the formula I wherein one of the substituents Y.sup.1.n. to Y.sup.2.n. is 4-aminobenzyl, R is NH2, wherein the second adequate substituent is hydrogen, where one of the substituents Y.sup.3.n. to Y.sup.4.n. it is methyl, the second adequate substituent being hydrogen, where Z is independently hydrogen, a monovalent, divalent or trivalent cation, by reacting the thiouhlic acid derivatives.

Description

Process for the preparation of the reactive isothiocyanate form of the DTPA benzyl derivatives

Technical field

The invention relates to a process for the preparation of 4-isothiocyanate-benzyl derivatives of DTPA of the general formula (I), in which exactly one of the substituents Y ¹ to Y ² is 4-isothiocyanatobenzyl (R is NCS). wherein the second adequate substituent is hydrogen, wherein just one of Y ³ to Y ⁴ is methyl, the other adequate substituent is hydrogen, wherein Z is independently hydrogen, a monovalent, divalent or trivalent cation, of the 4-aminobenzyl derivatives of DTPA of formula (I) wherein exactly one of Y ¹ to Y ² is 4-aminobenzyl (R is NH ₂ ), the other corresponding substituent is hydrogen, wherein just one of Y ³ to Y ⁴ is methyl, the other adequate substituent is hydrogen, wherein Z is independently hydrogen, monovalent, divalent or trivalent cation, on a laboratory or technological scale.

BACKGROUND OF THE INVENTION

The 4-isothiocyanate-benzyl derivatives of DTPA of formula (I) wherein R is NCS are a reactive form of a valuable DTPA ligand for conjugation with specific amino groups of biologically active supramolecules, for example monoclonal antibodies. Therefore, the main direction of use is the area of targeted diagnostics and therapy (so-called targeted drugs) of carcinomas or other pathological conditions of the human organism.

In the literature, the method for the preparation of said 4-aminobenzyl derivative of DTPA of formula (I) wherein R is NH _{2 is} not yet explicitly described.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The subject of the invention is a one-step synthesis of 4-isothiocyanate-benzyl derivatives

DTPA of formula (I), wherein R is NCS, by selective N-thiocarbonylation of amines of formula (I), wherein R is NH 2, which consists in the action of thiophosgene (II) derivatives

y

II (II) where X forms chlorine, bromine, fluorine, or thiocarbonates (III)

(III) wherein Y forms the so-called active thiocarbonate, preferably the heterocyclic thiocarbonates of group (IV), preferably generated in situ or prior to reaction from the reagents of group (II)

(IV)

and or preferably aliphatic thiocarbonates of group (V), preferably generated in situ or prior to reaction from the reagents of group (II)

Q ¹

Q ³

(V) wherein Q, Q ¹ , Q ² , Q ³ are independently bromo, fluoro, chloro, optionally with the aromatic thiocarbonates of group (VI), preferably generated in situ, or prior to reaction from the reagents of group (II)

wherein W ¹ , W ² , W ³ , W ⁴ , W ⁵ independently form hydrogen, fluoro, chloro, bromo, nitro, sulfo, sulfonyl, azo, diazonium, triazene, amido, imido, carboxyl, alkoxycarbonyl, aryloxycarbonyl, nitrile, alkoxy , oxonium, ammonium, or thiocarbondiamides (VII)

(VII)

wherein G ¹ , G ² , G ³ , G ⁴ are independently hydrogen, acyl, alkylsulfonyl, acylsulfonyl, sulfonyl, preferably from (VIIIa)

(Vlil)

or preferably cyclic thiocarbondiamide (IX)

(IX) or by the action of carbondisulfide (carbon disulfide, CS2), through the in situ generated dithiocarbamate of formula (X)

(X)

wherein XXX is an amine and M is an alkali metal or ammonium, optionally a tertiary amine associate with an adequate dithiocarbamic acid, or by the action of carbondisulfide (carbon disulfide, CS ₂ ), via in situ generated tetraalkylthiuram disulfide of formula (XI)

(XI) wherein XX is N, N-dialkylamine, or by the action of Ν, Ν, Ν ', Ν'-tetraalkylthiuram disulphide of formula (XI), wherein XX is N, N-dialkylamine, or carbonyl sulfide (COS), on 4-aminobenzyl derivatives of the formula (I) wherein exactly one of Y ¹ to Y ² is 4-aminobenzyl (R is NH ₂ ), wherein the other adequate substituent is hydrogen, wherein just one of Y ³ to Y * is methyl, the other adequate the substituent is hydrogen, wherein Z is independently hydrogen, a monovalent, divalent or trivalent cation.

The reaction is carried out at temperatures within a wide range of -30 to 135 ° C, in single and biphasic systems (liquid-liquid, liquid-solid phase), preferably in a micellar environment, optionally in a biphasic arrangement of two immiscible liquids, optionally in another preferred Embodiments in a two-phase system wherein one of the reactants is sorbed onto a solid support (substrate). The stoichiometric ratio of the reactants is chosen within a wide range of 0.05 to 20.

The reaction medium is constituted by at least one liquid, preferably using the effect of soluble or insoluble pH buffers to shift the reaction equilibrium. Inorganic carbonates, bicarbonates, hydroxides, phosphates and hydrogen phosphates, tetraborates, acetates, formates, ammonia, aliphatic tertiary amines, liquid or solid anion exchangers, or mixtures thereof, are preferably used for pH buffering.

When the reaction is carried out to give intermediates (X) and (XI), triethylamine, ammonia or dimethylamine is preferably used as the auxiliary amine.

When the reaction is carried out to give intermediates (X) and (XI), metal or transition metal salts, preferably ferric, copper, lead, mercury, salts are used to convert them to the corresponding isothiocyanates (formula (I), R is NCS). , or Lewis acids (BF3, AlCl3), or triphenylphosphine, optionally substituted triphenylphosphine or trialkylphosphite based systems, in the absence or presence of CCl4, respectively. CBr ₄ , or systems based on dialkyl chlorophosphites, optionally dialkyl chlorodithiophosphites, or alkyl chloroformates, or hexachlorodimethyl carbonate, or dicyclohexylcarbodiimide and dialkylcarbodiimides in general, preferably in the presence of activators, for example 4-N, N-dimethylaminopyridine.

When the reaction is carried out under the action of carbonyl sulphide (COS), Lewis acids, preferably POCl 3, POCl 3 + ZnCL, 2-sulphobenzoic anhydride, and the like, are used as reagents. mixtures thereof, or by the action of dicyclohexylcarbodiimide and dialkylcarbodiimides in general, preferably in the presence of activators, for example 4-N, N-dimethylaminopyridine.

The method is used in the preparation of enantiomerically pure 4-isothiocyanate-benzyl derivatives of DTPA (I) of the absolute configuration (R, R), (R, S), (S, R), (S, S) as well as mixtures of enantiomers, diastereoisomers and crude racemic mixtures. (AND).

It is a versatile, widely applicable and highly effective method of preparing 4-isothiocyanate-benzyl derivatives of DTPA of formula (I), wherein one of Y ¹ to Y ² is 4-isothiocyanatobenzyl (R is NCS), the other corresponding substituent being hydrogen, just one of Y ³ to Y ⁴ is methyl, the other corresponding substituent being hydrogen, wherein Z is independently hydrogen, a monovalent, divalent or trivalent cation. The products of formula I (R is NCS) are used to prepare chemically and biologically active substrates.

DETAILED DESCRIPTION OF THE INVENTION

Example 1: (2R) - (4-Isothiocyanatobenzyl) - (3S) -methyl DTPA

A solution of 1.5 g of thiophosgene (at least 91% content) in 50 ml of dry dichloromethane is added at room temperature with stirring to a solution of 5.1 g of (2R) - (4-aminobenzyl) - (3S) -methyl DTPA (at least 96%). %, HPLC), 7.5 g NaHCO3 and 105 mL water. The mixture was stirred vigorously for 12 hours at room temperature, then the organic layer was separated, washed with water and the aqueous fractions were combined. Carefully acidify at 0 ° C with 15 wt. phosphoric acid and extracted with five 75 ml portions of dichloromethane. Evaporation of dichloromethane, trituration with aqueous methanol and drying in a lyophilizer gave a total of 3.8 g (69.1%) of (2R) - (4-isothiocyanatobenzyl) - (3S) -methyl DTPA as a beige microcrystalline species.

Example 2: (2S) - (4-Isothiocyanatobenzyl) - (3S) -methyl DTPA

A solution of 1.45 g of thiophosgene (at least 90% content) in 60 ml of dry dichloromethane is added to the solution of 5.1 g of (2S) - (4-aminobenzyl) - (3S) -methyl DTPA (at least 97%) at room temperature with stirring. %, HPLC), 13 g of Na 2 HPO 4 and 130 ml of water. The mixture was stirred vigorously for 16 hours at room temperature, then the organic layer was separated, washed with water, the aqueous fractions were combined and evaporated at -55 ° C in a lyophilizer. The lyophilisate was triturated with 75 mL of methanol-acetone (1: 2, v / v) and the insoluble material was discarded. The product solution was evaporated at 20 ° C under vacuum and purified on a cation exchange column. A total of 2.3 g (53%) of (2S) - (4-isothiocyanatobenzyl) - (3S) -methyl DTPA was obtained as a yellowish microcrystalline species.

Example 3: 2- (4-isothiocyanatobenzyl) -3-methyl DTPA (crude enantiomeric mixture)

52.5 g of 2- (4-aminobenzyl) -3-methyl DTPA, 480 ml of water, 36 g of potassium bicarbonate and 17 g of potassium dihydrogen phosphate are charged to a 2 L reaction kettle equipped with a cooling apparatus and mechanical stirrer and mixed thoroughly. and then cooled to 0 ° C. A total of 19 g of thiophosgene dissolved in 60 ml of chloroform is then added so that the addition is not less than 25 minutes. The progress of the reaction was monitored by TLC. After stirring for 8 hours, the temperature is allowed to rise slowly to room temperature and stirred for an additional 180 minutes. The organic phase was removed, the mixture was cooled again to 0 ° C and acidified to pH 5.5 with phosphoric acid.

Extraction with ten 75 ml portions of dichloromethane and evaporation gave a total of 41.3 g (74.5%) of 2- (4-isothiocyanatobenzyl) -3-methyl DTPA as the original enantiomeric mixture.

Example 4: (2R) - (4-Isothiocyanatobenzyl) - (3S) -methyl DTPA

It is obtained in 69% yield according to the methodology described in Example 1, except that a vinylpyridine copolymer anion exchange slurry is used as the base.

Example 5: (2R) - (4-Isothiocyanatobenzyl) - (3R) -methyl DTPA

It is obtained in a yield of 88% according to the methodology described in Example 1 except that lithium carbonate in excess of 250 mol% is used as the base and the separation is carried out on a cation exchanger based on a sulphonated styrene-divinylbenzene copolymer.

Example 6: 2- (4-isothiocyatobenzyl) -3-methyl DTPA (racemic mixture)

It was obtained in 93% yield according to the methodology described in Example 3 except that an aqueous 4 wt. triethylamine-phosphoric acid system (pH 9.3).

Example 7: (2R) - (4-Isothiocyanatobenzyl) - (3R) -methyl DTPA

It is obtained in 84% yield according to the methodology described in Example 1 except that potassium bicarbonate is used as the base and the reaction is carried out in a micellar medium of 0.4% by weight. sodium lauryl sulfate. The separation is carried out on a cation exchanger.

Example 8: (2S) - (4-Isothiocyanatobenzyl) - (3R) -methyl DTPA

While stirring at room temperature, a solution of 3.8 g of thiophosgene (at least 91% content) in 30 ml of dry dichloromethane is added to a solution of 1.25 g of N-hydroxysuccinimide in 50 ml of dry dichloromethane and 2.2 g of triethylamine. The mixture was stirred under a chloro-calcium cap for an additional 8 hours and then a total of 5.08 g of (2S) - (4-aminobenzyl) (3R) -methyl DTPA (minimum 97% content, HPLC) was added to the mixture and stirred for an additional 8 hours . After working up as in Example 2, 4.33 g (78%) of isothiocyanate is obtained.

Example 9: (2S) - (4-Isothiocyanatobenzyl) - (3S) -methyl DTPA

It is obtained in a yield of 74% analogous to Example 8 except that N-hydroxybenztriazole is used as the mediator.

Example 10: (2S) - (4-Isothiocyanatobenzyl) - (3S) -methyl DTPA

It is obtained in a yield of 51% analogous to Example 8, except that bis- (pentachlorophenyl) thiocarbonate is used as the mediator.

Example 11: (2R) - (4-Isothiocyanatobenzyl) - (3R) -methyl DTPA 1

and

It is obtained in a yield of 93% analogous to Example 8, except that the reaction product of the sodium salt of 4-toluenesulfonamide and trifluoromethanesulfonyl chloride subsequently treated with thiophosgene, which is prepared before the reaction in the same vessel, is used as the mediator.

Example 12: (2R) - (4-Isothiocyanatobenzyl) - (3R) -methyl DTPA

To a solution of 9.6 g of methanesulfonic acid in 120 ml of dimethylformamide was added with stirring 1.1 g of sodium methoxide. Subsequently, 3.6 g of trifluoromethanesulfonyl chloride in 25 ml of dichloromethane are added dropwise. The crude imide mixture is cooled to -10 ° C and 1.08 g of sodium methoxide (min. 98% content) and 1.2 g of thiophosgene in 15 ml of dichloromethane are gradually added. To the resulting dark mediator solution was added 5.08 g of (2R) - (4-aminobenzyl) - (3R) -methyl DTPA without separation, and the resulting mixture was stirred under a nitrogen atmosphere for 48 hours. It was worked up analogously to Example 2. The yield was 70

Example 13: (2R) - (4-Isophthiocyanatobenzyl) - (3S) -methyl DTPA

10.2 g of (2R) - (4-aminobenzyl) - (3S) -methyl DTPA are dissolved in 420 ml of dry acetonitrile and 18 g of triethylamine, and after addition of 1.5 g of carbon disulfide, they are stirred at 5 ° C for 3 hours. The temperature was then allowed to slowly rise to 20 ° C and stirring was continued for another 8 hours. The reaction mixture was cooled to -8 ° C and a total of 2.6 ethyl chloroformate in 10 mL of dichloromethane was added over 15 minutes. The product was isolated analogously to Example 2 to give 81% isothiocyanate.

Example 14: (2R) - (4-Isothiocyanatobenzyl) - (3R) -methyl DTPA

It is obtained in a yield of 59% analogous to Example 13 except that the triphenylphosphine-tetrachloromethane system in acetonitrile is used to decompose the dithiocarbamate.

Example 15: (2S) - (4-Isothiocyanatobenzyl) - (3S) -methyl DTPA

It is obtained in a yield of 54% analogous to Example 14.

Example 16: (2S) - (4-Isothiocyanatobenzyl) - (3R) -methyl DTPA

It is obtained in a yield of 17% analogous to Example 13, except that sodium hydroxide is used as the base and the reaction is carried out in aqueous ethanol at 35 ° C.

Example 17: (2S) - (4-Isothiocyanatobenzyl) - (3S) -methyl DTPA

It was obtained in a yield of 66% analogous to Example 13 except that dicyclohexylcarbondiimide in acetonitrile was used to decompose the dithiocarbamate. !

Claims (16)

A process for the preparation of N-carboxymethylated amines of formula (XII): Y ¹ oz (ΧΠ) wherein exactly one of Y ¹ to Y ² is 4-isothiocyanatobenzyl, the other of which is hydrogen, where one of Y ³ to Y ⁴ is methyl, the other of which is hydrogen, wherein Z is independently hydrogen, a monovalent, divalent or trivalent cation, characterized in that the amines of the general formula (XIII), Y ¹ oz (xni) wherein just one of Y ¹ to Y ² is 4-aminobenzyl, wherein the other adequate substituent is hydrogen, wherein just one of Y ³ to Y ⁴ is methyl, the other adequate substituent is hydrogen, wherein Z is independently hydrogen, a monovalent, divalent or trivalent cation, acts with an agent from the group of thiocarbonic acid derivatives (XIV) (XIV) and 1: The method according to claim 1, characterized in that the thio-carbonic acid derivative is a thiophosgene analogue ((XIV), wherein X is chlorine, bromine, fluorine), preferably thiophosgene itself. The method according to claim 1, characterized in that the thiocarbon derivative is an agent of the group of thiocarbonates (XV) (XV), wherein Y forms the so-called active thiocarbonate, preferably a heterocyclic thiocarbonate of group (XVI), of x (xvi). ) or or in another preferred embodiment aliphatic thiocarbonates of group (XVII); 4 » Λ 4 4 r »i / Q 9 « 4 «t * • 4 * • wherein Q, Q ¹ , Q ² , Q ³ are independently bromo, fluoro, chloro, optionally in another preferred embodiment aromatic thiocarbonates of (XVIII), (XVIII) wherein W ¹ , W ² , W ³ , W ⁴ , W ⁵ independently form hydrogen, fluoro, chloro, bromo, nitro, sulfo, sulfonyl, azo, diazonium, triazene, amido, imido, carboxyl, alkoxycarbonyl, aryloxycarbonyl, nitrile, alkoxy, oxonium, ammonium, The method of claim 1, wherein the thiocarbonic acid derivative is a thiocarbondiamide (XIX) agent with a (XIX) wherein G ¹ , G ² , G ³ , G ^{4 are} independently hydrogen, acyl, alkylsulfonyl, acylsulfonyl, sulfonyl, preferably group (XX) SO-SO ₂ CH ₃ CF ₃ (XX) and / or in another preferred embodiment the cyclic thiokarbondiamid (XXI) (XXI) A process according to claim 1, characterized in that the thiocarbonic acid derivative is carbondisulfide (carbon disulphide, CS2), by means of an in situ generated dithiocarbamate of formula (XXII) φ φ * wherein ΖΖΖ is an amine and Μ is an alkali metal or ammonium, optionally a tertiary amine associate with an adequate dithiocarbamic acid, or via an in situ generated tetraalkylthiuram disulfide of formula (XXIII) (XXIII) wherein Z 2 is Ν, Ν-dialkylamine, A process according to claim 1, characterized in that the thiocarbonic acid derivative is Ν, Ν, Ν ', Ν'-tetraalkylthiuram disulfide of the general formula (XXIII), wherein Z 2 is N, N dialkylamine. The method of claim 1, wherein the thiocarbonic acid derivative is carbonyl sulfide (COS). Process according to claim 1, characterized in that the reaction is carried out at temperatures within a wide range of -30 to 135 ° C, preferably at room temperature. Method according to claim 1, characterized in that the reaction is carried out in both single-phase and two-phase systems (liquid-liquid, liquid-solid phase), preferably in a micellar environment, optionally in a two-phase arrangement of two immiscible liquids, optionally in another preferred Embodiments in a two-phase system wherein one of the reactants is sorbed on a solid support (substrate). The process of claim 1 wherein the molar ratio of the reactants is selected within a wide range of 0.05 to 20. Method according to claim 9, characterized in that the reaction medium is constituted by at least one liquid, preferably using the effect of soluble or insoluble pH buffer (s) to shift the reaction equilibrium. Inorganic carbonates, bicarbonates, hydroxides, phosphates and hydrogen phosphates, tetraborates, acetates, formates, ammonia, aliphatic tertiary amines, liquid or solid anion exchangers, or mixtures thereof, are preferably used for pH buffering. Process according to claim 5, characterized in that the reaction is preferably carried out with an amine selected from the group: triethylamine, ammonia or dimethylamine. 4 · 4 ·············· Process according to claim 5, characterized in that metal or transition metal salts, preferably salts of ferric, cupric, lead, mercuric or Lewis acids () are used for the conversion of the intermediates (XXII) and (XXIII) to the corresponding isothiocyanates (XII). BF ₃ , AlCl 3), or systems based on triphenylphosphine, optionally substituted triphenylphosphine, optionally trialkylphosphites, in the presence or absence of CCl ₄ or CBr ₄ , or systems based on dialkylchlorophosphites, optionally dialkylchlorodithiophosphites, or alkylchloroformates, or hexachlorodimethylcarbodiocarbide, , in the presence of activators, for example 4-N, N-dimethylaminopyridine. Method according to claim 7, characterized in that Lewis acids, preferably of the POCl 3, POCl 3 + ZrCl 2, 2-sulfobenzoic anhydride or POCl 3 system are used as reagents. mixtures thereof, or by the action of dicyclohexylcarbodiimide and dialkylcarbodiimides in general, preferably in the presence of activators, for example 4-N, N-dimethylaminopyridine. Process according to claims 4 and 5, characterized in that the reaction is preferably carried out by reacting intermediates (XV) and (XIX) in situ or prior to reaction from the reagents of group (XIV), wherein X is chlorine, bromine, fluorine. The process according to claim 1, characterized in that the reaction is carried out with enantiomerically pure 4-aminobenzyl derivatives of DTPA (XIII) of the absolute configuration (R, R) or (R, S) or (S, R) or (S, S). as well as mixtures of enantiomers, diastereoisomers, or racemic mixtures.