CS254731B1 - 1- (2-Chloroethyl) -3- [4- (6-purinylthio) butyl] urea - Google Patents

Abstract

The solution relates to 1-(2-chloroethyl)- “3“ E4“(6-purinylthio)butyl ureas of the general formula I s(ch2)4nhconch2ch2ci (I) in which X denotes a hydrogen atom or a nitroso group and a method of their production consisting in the reaction of 6-(4-aminobutylthio)purine with 2-chloroethylisocyanate and in the subsequent nitrosation of the resulting urea to 1-(2-chloroethyl)-1-nitroso- -3-[4-(6-purinylthio)butyl]urea. Nitrosourea showed significant antineoplastic activity in animals with experimental tumors

Description

The invention relates to 1- (2-chloroethyl) -3- [4- (6-purinylthio) butyl] urea of formula I with (CH _{2) 4} nhconch ₂ CH ₂ C

Ν. X in which X represents a hydrogen atom or a nitro group and a process for their preparation.

Nitrosoureas, mainly 3-substituted 1- (2-chloroethyl) -1-nitrosoureas, are alkylating-type cytostatics, some of which, mainly 1- (2-chloroethyl) -3-cyclohexyl-1-nitrosoureas (CCNU; NSC 79 037) is widely used in clinical practice. However, more preferred carriers for the alkylating-acting 3- (2-chloroethyl) -3-nitrosoureidic residue of said cytostatics are still sought. The compounds according to the invention contain, as such, a 4- (6-purinylthio) butyl group derived from the antineoplastically active 5- (6-purinylthio) valeric acid (see U.S. Pat. No. 82,287) and have both an alkylating action and an purine nucleic acid base antimetabolites.

According to the invention, 1- (2-chloroethyl) -3- [4- (6-purinylthio) butyl] ureas of the formula I are produced by the process of 6- (4-aminobutylthio) purine of the formula II

H reacts with 2-chloroethyl isocyanate of formula (III) cich ₂ ch ₂ nco (III) and the resulting 1- (2-chloroethyl) -3- [4- (6-purinylthio) butyl] urea of formula Ia with (ch ₂ ) ₄ n-chloro ₂ ch ₂ ci

(1a) is nitrosated by treatment with nitrous acid to give 1- (2-chloroethyl) -1-nitroso-3- [4- (6-purinylthio) butyl] urea of formula 1b with (ch ₂ ) ₄ nhconch ₂ ch ₂ ci

NO (lb)

The new 6- (4-aminobutylthio) purine of formula II is used as the starting compound in the preparation of urea of formula Ia. Out! the amino compound of formula II is produced by Curtius degradation of the acid azide

5- (6-Purinylthio) Valer Formula IV S (CH ₂ ) ₄ CON ₃ (IV)

by boiling with hydrochloric acid.

The reaction of the 2-chloroethyl isocyanate of formula III with 6- (4-aminobutylthio) purine of formula II is carried out in a suitable inert solvent such as dioxane, tetrahydrofuran, dimethylformamide or dimethylsulfoxide at a temperature ranging from room temperature to 70 ° C. The desired product of formula (Ia) is isolated from the reaction mixture by conventional means, preferably by pouring the reaction mixture into water and crystallizing the filtered, relatively very pure crude material.

. The nitrosation of the urea of the formula Ia to the nitroso derivative of the formula Ib is conveniently carried out in an anhydrous medium, preferably in a solution of the compound of the formula Ia in a lower aliphatic organic acid, e.g. formic acid or acetic acid. sodium nitrite, or a lower alkyl nitrite, for example butyl nitrite. The reaction is carried out at a temperature of +5 to +20 ° C, using 1.2 to 2 mol equivalents of alkali metal nitrite or alkyl nitrite. The desired nitroso derivative of formula (Ib) is isolated from the reaction mixture by known methods, preferably by diluting the reaction mixture with water, filtering off the crude product and purifying it by column chromatography and / or crystallization. The nitrosoraurea of the formula Ib is a light yellow crystalline substance sensitive to heat and alkali.

The conversion of the azide of formula IV to the amine of formula II is effected by successively introducing the solid azide or slowly dropping its solution in a suitable inert solvent, such as dioxane or tetrahydrofuran, into boiling dilute, preferably 0.1-0.5 M hydrochloric acid. The rate of azide addition is governed by the intensity of the reaction of evolving nitrogen, which, upon rapid addition, may become of a vigorous nature. As a side reaction, the sulfide bond cleavage in the compound of formula II takes place under the action of hydrochloric acid at a higher temperature to form hypoxanthine; it is therefore expedient to carry out said azide degradation as quickly as possible. The desired azide of formula IV can be prepared as described above by treating sodium nitrite with a solution of 5- (6-purinylthio) valeric acid hydrazide in dilute hydrochloric acid (see U.S. Pat. No. 128,123).

The required 2-chloroethyl isocyanate is a commercially available preparation or can be prepared by the methods described (see, for example, Siefken W., Ann. Chem. 562, 103 (1949)).

The nitrosourea of formula Ib, when tested in experimental mouse and rat tumors, had an antitumor effect compared to control untreated animals, either by decreasing the average tumor weight value or the prolonged average survival time, or favorably affecting both. A useful therapeutic effect of this substance has been demonstrated, for example, in H mice with Crocker sarcoma 180, where, compared to the control group, the substance is 200 mg / kg p.o. reduced tumor weight to 39% and concurrently increased survival time to 132%. In DBA / 2 mice with L1210 leukemia at the same dose, the substance prolonged the lifespan of the treated animals to 151%.

The antitumor effect, manifested by a decrease in the mean total ascitocrit value, has also been demonstrated in animals with other experimental tumors; for example after a dose of 200 mg / kg p.o. a decrease in total ascitocrit values in mice with ATE tumors has been demonstrated (73%),

Sa37 (71%), Kr2 (47%) and NK (83%). After half-dose (1 x 100 mg / kg p.o.), there was a significant reduction in these values in Sa37 (70%) and Kr2 (66%) tumor mice. At Yoshida's tumor,

Zajdel's ascitic hepatoma and solid forms of Ehrlich's tumor have not been shown to have an antitumor effect. In vitro experiments on Yoshid's tumor cells markedly predominated inhibition

-5-1 DNA biosynthesis (IC _cr . For 5-iodo-2'-deoxy / 6- H) uridine 1.8 * 10 mol.l) over inhibition for ^bU 14 -4-tumor cell theosynthesis (IC, - _n pro (U - C) amino acid mixture 6.10 mol.l, with a pre-· ^υ -7 -4 -1 protein degradation weight over proteosynthesis at a concentration interval of 10 to 10 mol.l).

For the compound of formula Ia, the antitumor effect was indicated at a dose of 8 x 100 mg / kg p.o. in mice with Crocker tumor 180 (111% survival) and Sa37 (107% survival).

The process according to the invention is illustrated in more detail by the following non-limiting examples. The melting points of the compounds are determined on a Kofler block and are given, as with other temperature data, in ° C. The percentages are given in% by weight.

Example 1

1- (2-chloroethyl) -3- [4- (6-purinylthio) butyl] urea (Ia)

To a suspension of 2.23 g (0.01 mol) of 6- (4-aminobutylthio) purine in 16 ml of anhydrous dimethylformamide was added with stirring 1.06 g (0.01 mol) of 2-chloroethyl isocyanate and the mixture was heated on a bath for 2 h. 50 to 55 ° C warm. The solution was allowed to stand overnight at room temperature, then poured into 50 ml of ice-water, acidified to pH 3 with dilute hydrochloric acid (1: 5) and the precipitated product was filtered off. 1.45 g (68% yield) of compound Ia, m.p. 142-145 ° C (dilute acetic acid).

Example 2

1- (2-chloroethyl) -1-nitroso-3- [4- (6-purinylthio) butyl] urea (Ib)

To a solution of 1.64 g (5 mmol) of 1- (2-chloroethyl) -3- [4- (6-purinylthio) butyl] urea (Ia) in 4 mL of 99.5% formic acid is stirred with stirring at + 5-7 ° C, 0.47 g (6.8 mmol) of triturated sodium nitrite are added in portions. The reaction mixture is stirred for 1 hour at this temperature, then poured into 40 ml of ice-water and the precipitated oily product which solidifies on standing is filtered off. The crude product (1.49 g) was chromatographed on a silica gel column using 9: 1 chloroform: ethanol to elute the compounds. From the combined single fractions containing the less polar material, the solvents are distilled off under reduced pressure, the residue is dissolved in formic acid, the solution is diluted with water and the precipitated substance is filtered off. 0.99 g (yield 55.3%) of the nitrosourea Ib, m.p. M.p. 142-143 ° C.

Example 3

6- (4-Aminobutylthio) purine (II)

To a solution of 4.0 g (15 mmol) of 5- (6-purinylthio) valeric acid hydrazide in 150 ml (30 mmol) of 0.2 M hydrochloric acid was added dropwise with stirring and cooling at 0 to +3 ° C. about 15 min. a solution of 150 mL (15 mmol) of 1 M sodium nitrite. The reaction mixture is stirred at this temperature for 1.5 h, then neutralized with 15 ml (15 mmol) of a 1 M aqueous solution of sodium bicarbonate and the precipitated azide is filtered off after 1 h and washed with water. The still wet azide (4.1 g) was dissolved in 40 ml dioxane at room temperature and the solution was added dropwise to boiling 0.2 M aqueous hydrochloric acid (75 ml, 15 mmol) over about 10 min. The mixture is heated at reflux for a further 5 min, then concentrated under reduced pressure to a volume of about 5 ml and the solution is diluted with 60 ml of hot acetone. After cooling, 2.9 g (yield 74.4%) of 6- (4-amino-butylthio) purine hydrochloride precipitated, which after recrystallization from aqueous acetone had m.p. Mp 237-238 ° C.

The base was dissolved from a solution of 2.6 g (10 mmol) of the above hydrochloride in 13 mL of water by addition of 1.05 mL (10.5 mmol) of 10 M sodium hydroxide. Base II dihydrate (1.84 g, 70.8% yield) was obtained, m.p. 94 DEG-96 DEG C., which on drying at 100 DEG C./7 mbar, loses crystalline bound water and then has a m.p. Mp 167-168 ° C.

Claims (3)

SUBJECT OF THE INVENTION 1- (2-Chloroethyl) -3- [4- (6-purinylthio) butyl] urea of formula I S (CH ₂ NH ₄ CH ₂ ) CH ₂ Cl ₂ X X in which X represents a hydrogen atom or a nitro group. (AND), 2. A process for the preparation of 1- (2-chloroethyl) -3- [4- (6-purinylthio) butyl] urea according to claim 1, which comprises 6- (4-aminobutylthio) purine of formula II (II). , reacts with 2-chloroethyl isocyanate of formula (III) cich ₂ ch ₂ nco (III) to give 1- (2-chloroethyl) -3- (4- (6-purinylthio) butyl) urea of formula Ia S (CH ₂ ) ₄ NHCONHCH ₂ CH ₂ Cl (1a), optionally nitrosated with nitrous acid to give 1- (2-chloroethyl) -1-nitroso-3- [4- (6-purinylthio) butyl] urea of formula Ib with (ch ₂ ) ₄ nhco ^ their ₂ ch ₂ ci NO (Ib) 3. Process according to claim 2, characterized in that the nitrosation is carried out in a lower aliphatic carboxylic acid medium, preferably in a formic or acetic acid medium, by treatment with an alkali metal nitrite or a lower alkyl nitrite at a temperature of +5 to +20 ° C.