NOVEL 1-ALKYL-1-SULFONYL-2-ALKOXYCARBONYLSULFENYLHYDRAZINES HAVING ANTINEOPLASTIC ACTIVITY

Abstract: Compounds of the formula: wherein R₁ is a lower alkyl of 1-6 carbon atoms, benzyl, phenyl or phenyl substituted by halogen, alkoxy of 1 to 4 carbon atoms, alkyl of 1 to 4 carbon atoms, amino, or carbonyl substituents, or -RN(R′)₂ wherein R and R′ are each independently alkyl of 1 to 4 carbon atoms; R₂ is a heterocycle or an aromatic substituent and each A is an aromatic substitution independently selected from the group consisting of hydrogen, alkyl of 1-4 carbon atoms, alkoxy of 1-4 carbon atoms, halogen, -NO₂, -NH₂, -COOH, and -NHCOCH₃. The compounds have been found to be alkylating agents having antineoplastic activity for use in inhibiting the growth of tumors.

Description: This invention relates to novel compounds having antineoplastic activity, i.e. activity for inhibiting the growth of malignant tumors. More specifically, it relates to compounds of the class 1- alkyl-1-sulfonyl-2-alkoxycarbonylsulfenylhydrazines and their use in inhibiting malignant tumors. These novel compounds constitute a new class of alkylating agents. Alkylating agents capable of methylation of biological molecules form a useful group of antineoplastic agents, with procarbazine, streptozotocin and dacarbazine being examples of clinically active agents of this type. The assignee hereof has also discovered another class of N, N′- bis (sulfonyl)hydrazines useful for inhibiting the growth of malignant tumors. These compounds are described in EP185387 and corresponding US 4684747. See also Shyam et al. , J. Med. Chem., 28, 525 (1985). The compounds described therein are of a different structure. An object of this invention is to provide a new class of alkylating agents having antineoplastic activity. A further object is to provide compositions containing such agents in a form suitable for administration to host organisms. A still further object is to provide a method for preparing the novel alkylating agents. A still further object is to provide novel compounds which have activity against malignant tumors. This invention relates to compounds of the formula: wherein R₁ is an alkyl of 1-6 carbon atoms, benzyl, phenyl, or phenyl substituted by halogen, alkoxy of 1 to 4 carbon atoms, alkyl of 1 to 4 carbon atoms, amino or carbonyl substituents, or -RN(R')₂ wherein R and R' are each independently an alkyl of 1 to 4 carbon atoms, and R₂ is a heteroaryl substituent in which the heteroatom is sulphur, oxygen, nitrogen or a combination thereof and each A is a substituent independently selected from the group consisting of hydrogen, alkyl of 1-4 carbon atoms, alkoxy of 1-4 carbon atoms, halogen, and n is 1, 2 or 3. The compounds have been found to be alkylating agents having antineoplastic activity for use in inhibiting the growth of malignant tumors, i.e. exhibit pronounced antitumor activity. In addition, they probably have low mammalian toxicity. The compounds may suitably be administered to a host organism internally in the form of conventional pharmaceutical preparations, for example, in conventional pharmaceutically acceptable enteral or parenteral excipients. The compounds described above are a new class of antineoplastic agents. A number of them have been synthesized and tested with demonstrable effectiveness against the B16 melanoma and/or L1210 leukemia transplanted rodent tumors. These compounds possess the capacity to generate an alkylating species under physiological conditions. As indicated above, the compounds have the general formula: R₁ may be an alkyl of 1-6 carbon atoms. As used herein, the term "alkyl" represents straight or branched carbon chains. Preferably, R₁ is methyl, but may also be ethyl, isopropyl, or tert-butyl. R₁ may also be a benzyl or a phenyl substituent or a phenyl substituent substituted by halogen, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, amino or carbonyl substituents. R₁ may also be -RN(R')₂ wherein R and R' may each independently be an alkyl of 1 to 4 carbon atoms, e.g. R is -CH₂CH₂ and R' is CH₃. R₂ is heteroaryl, wherein the heteroatom is N, O and/or S, such as the unsaturated 5-member rings exemplified by and other heterocycles such as quinolinyl Each A is a substituent which may be hydrogen. When this occurs, the heteroaryl substituents are considered unsubstituted. Otherwise, the heteroaryl substituent may be substituted by an A which is an alkyl or alkoxy of 1-4 carbon atoms, including straight or branched chain hydrocarbons or halogen. The term "halogen" is meant to include all four halogens, namely chlorine, bromine, iodine and fluorine. Chlorine and bromine are the preferred halogens, n is preferably 1 or 2. The compounds of this invention may be made by the methodology shown in Scheme I: wherein R₁, R₂ and A are as previously defined. The N-methyl-N-sulfonylhydrazides were prepared by reacting the appropriate sulfonyl chloride with methylhydrazine in a 1:2 molar ratio in tetrahydrofuran, see Friedman, et al ., Org. Synth. Coll. Vol. 5, 1055 (1973), the entire disclosure of which is incorporated herein by reference. The appropriate sulfonyl chlorides may be obtained commercially. The 1-methyl-1-arylsulfonylhydrazines are prepared eg by reacting the appropriate sulfonyl chlorides with methylhydrazine in tetrahydrofuran. The reaction of these intermediates for instance in diethyl ether with about one equivalent of pyridine and one equivalent of alkoxycarbonylsulfenyl chloride produces the claimed products herein. Other solvents may be used, e.g. methylene chloride, chloroform. Furthermore, other organic bases may also be incorporated, e.g. triethylamine, lutidine. The compounds of this invention are preferably administered internally, in the form of conventional pharmaceutical preparations, for example, in conventional enteral or parenteral pharmaceutically acceptable excipients containing organic and/or inorganic inert carriers, such as water, gelatin, lactose, dimethylacetamide, starch, magnesium stearate, talc, plant oils, gums, alcohol, vaseline, or the like. The pharmaceutical preparations can be in solid forms, for example, tablets, dragees, suppositories, capsules, or the like or conventional liquid forms, such as suspensions, emulsions, or the like. If desired, they can be sterilized and/or contain conventional pharmaceutical adjuvants, such as preservatives, stabilizing agents, wetting agents, emulsifying agents, buffers, or salts used for the adjustment of osmotic pressure. The pharmaceutical preparations may also contain other therapeutically active materials. The pharmaceutical preparation should include an amount of a compound of this invention effective for antineoplastic activity. The effective dosage will depend on the antineoplastic activity and toxicity of the particular compound employed, and is thus within the ordinary skill of the art to determine for any particular host mammal or other host organism. Suitable may be, for example, in the range of about 2-15 mg/kg for man. Typical non heteroaryl compounds are described in the Journal Medicinal Chemistry, vol. 29, no. 9, September 1986 page 1777-1779. These include 1) 1-Benzenesulfonyl-2-methoxycarbonylsulfenyl-1-methylhydrazine 2) 2-Methoxycarbonylsulfenyl-1-methyl-1-(4-methylbenzenesulfonyl)hydrazine 3) 1-(4-Methoxybenzenesulfonyl)-2-methoxycarbonylsulfenyl-1-methylhydrazine 4) 1-(4-Bromobenzenesulfonyl)-2-methoxycarbonylsulfenyl-1-methylhydrazine 5) 2-Methoxycarbonylsulfenyl-1-methyl-1-( -toluenesulfonyl)hydrazine 6) 2-Methoxycarbonylsulfenyl-1-methyl-1-(2-naphthalenesulfonyl)hydrazine It has been found that the above non-heteroaryl compounds can be compared to the heteroaryl compounds of this invention. Typical compounds of the present invention include: 7) 1-(2-Thienyl)sulfonyl-1-methyl-2-methoxycarbonylsulfenylhydrazine 8) 1-(3,5-Dimethylisoxazolyl)sulfonyl-1-methyl-2-methoxycarbonylsulfenylhydrazine 9) 1-(5-Chloro-1,3-dimethylpyrazolyl)sulfonyl-1-methyl-2-methoxycarbonylsulfenylhydrazine 10) 1-(8-Quinolinyl)sulfonyl-1-methyl-2-methoxycarbonylsulfenylhydrazine The following is a theoretical mechanism by which the compounds of this invention are activated based on the examples shown herein and previous work. As previously demonstrated, a variety of 1-methyl-1,2- bis (arenesulfonyl)hydrazines (see U.S. Serial No. 06/683,852 filed on December 20, 1984 and the continuation-in-part thereof U.S. Serial No. 06/810,644, filed December 18, 1985 now U.S. Patent No. 4 684 747 and Shyam, Cosby and Sartorelli , J. Med. Chem., 28, 525 (1985)) have been shown to be effective against the L1210 leukemia and B16 melanoma in mice. These compounds have the following formula: in which Ar and Ar′ are aromatic substituents. The compounds break down under physiological conditions to generate the putative alkylating species which has the formula: ArSO₂-N=N-CH₃ III This was hypothesized to account for the observed biological activity of these compounds. Replacement of the 2-arenesulfonyl group in the compound of Formula II by methoxycarbonylsulfenyl moiety to form a 1-methyl-1-arenesulfonyl-2-alkoxycarbonylsulfenylhydrazine of the following formula (an example of the invention) provides a compound which is capable of decomposing by the same mechanism as the compounds of Formula II to give the methylating species shown below: The compounds claimed herein also possess the ability to react directly with the sulphur atom of biological nucleophiles such as glutathione or various sulphur containing proteins to give methyldiazene, the postulated alkylating species derived from procarbazine (see Reed , "Procarbazine" in Antineoplastic and Immunosuppressive Agents, Part II ed. by Sartorelli and Johns . Berlin: Springer-Verlag, 1975, pp. 747-765) which can undergo further homolytic cleavage to generate the methyl radical, hydrogen radical and nitrogen. An example is depicted in the Scheme II. EXAMPLES OF COMPOUNDS General procedure for the preparation of 1-methyl-1-sulfonyl-2-alkoxycarbonylsulfenylhydrazines. Methoxycarbonylsulfenyl chloride (6.0 mmol) was slowly added dropwise to an ice-cold suspension of the appropriate 1-methyl-1-sulfonylhydrazide (6.0 mmol) (see the aforementioned Friedman et al ) in anhydrous diethyl ether (50 ml) and pyridine (6.0 mmol) while maintaining the temperature below 10°C. After stirring at a temperature of between 0-5°C for 15 minutes, the mixture was filtered and the ethereal solution washed twice with ice-cold dilute hydrochloric acid (25 ml portions; 1:1, v/v) followed by three washings with brine (25 ml portions). The organic phase was dried (MgSO₄) and the diethyl ether evaporated in vacuo to give an oil which solidified upon trituration with light petroleum ether. Recrystallization from warm ethanol (50°C) gave the pure compound. NMR spectral data were as expected. Examples of Antitumor Activity The B16 melanoma was propagated as a solid tumor in C57B1 mice. Transplantation was carried out by removing tumor's from donor mice bearing 14-day subcutaneous tumor growths. The tissue was fragmented to make a well-dispersed cellular suspension and diluted with Fischer's medium without serum so that one gram of tissue was suspended in 5 ml of solution. A portion (0.2 ml) of the resulting cell suspension was injected intraperitoneally into each recipient animal. The ascites cell form of the L1210 leukemia was propagated in CDF-1 mice. Transplantation was carried out using donor mice bearing 7-day tumor growths; experimental details are described in Agrawal et al. , J. Med. Chem., 11, 700, 1968, incorporated herein by reference. Dosage levels of all compounds were administered over a range of 12.5 to 50 mg/kg by intraperitoneal injection, beginning 24 hours after tumor implantation, once daily for 6 consecutive days. The test compounds were injected as fine suspensions following homogenization in 2 to 3 drops of 20% aqueous Tween 80 and then made up to volume with isotonic saline. All drugs were administered intraperitoneally in a volume of 0.5 ml and for experiments animals were distributed into groups of five mice of comparable weight and maintained throughout the course of the experiment on Laboratory Chow pellets and water ad libitum . Control tumor-bearing animals given injections of comparable volumes of vehicle were included in each experiment. Mice were weighed during the course of the experiments, and the percent change in body weight from onset to termination of therapy was used as an indication of drug toxicity. Determination of the sensitivity of neoplasms to these agents was based on the prolongation of survival time afforded by the drug treatments. Tables II and III are comparative data representing results obtained using non-heteroaryl compounds. Example of Determination of Alkylating Ability of Compounds A solution of the test sample (12 micromol) in dimethylsulfoxide (1 ml), distilled water (2 ml), Tris-HCl buffer (pH 7.4; 1 ml) was incubated with 4-(4-nitrobenzyl)pyridine (148 micromol in 0.4 ml acetone) at 37°C for 1 hour. Following addition of acetone (2 ml) and 0.25 M sodium hydroxide solution (1.5 ml), the material was extracted with ethyl acetate (5 ml) and the absorbance determined at 540 nm. Discussion of Results of Examples The tumor-inhibitory properties of compounds 1-10 were determined by measuring their effects on the survival time of mice bearing the B16 melanoma. The results of tests conducted are summarized in Tables II and IV. All of the compounds synthesized displayed significant activity against the B16 melanoma, with increases in the survival time of tumor-bearing animals being between 40% and 150%. Although compound 10 was somewhat more active than the other derivatives, no clear-cut correlation was evident between the leaving group ability of the arene- or heteroarenesulfonyl substitution, i.e. -SO2R2-A, and antineoplastic activity in this system. Thus, in general terms the hetroarene derivatives are as active as the arene derivatives. The only difference between these compounds resided in the variation of the proposed leaving group and this did not appear to significantly alter their activity. Compounds 1 to 5 and 7 to 10 were also evaluated for anticancer activity against mice bearing the L1210 leukemia and the results are summarized in Tables III and V. All of these compounds were found to be inactive against this tumor with the exception of compounds 3 and 10 which displayed only limited activity. This finding contrasts with previous results with 1-methyl 1,2- bis (arenesulfonyl)hydrazines which showed significant activity against the L1210 leukemia (see U.S. Serial No. 06/683,852 filed on December 20, 1984 and the continuation-in-part thereof, U.S. Serial No. 810,644 filed December 18, 1985 now U.S. Patent No 4 684 747, as well as Shyam et al ., J. Med. Chem., 28, 525 (1985)). This suggests that these compounds decompose in vivo to form a different reactive species than that proposed for the 1-methyl-1,2 bis (arenesulfonyl)hydrazines, and that the 1-methyl-1-sulfonyl-2-alkoxycarbonylsulfenylhydrazines represent a different class of compounds with potential clinical activity. A modification of the method of Wheeler and Chumley (J.Med. Chem., 10 259 (1967) was used to examine whether aromatic derivatives of this type of compound possessed alkylating ability. This method measured the absorbance at 540 nm of the alkylated product of 4-(4-nitrobenzyl) pyridine. It was found that alkylating ability and antitumour activity against the B16 melanoma were linked so that compounds demonstrating antitumor activity against the B16 melanoma showed significant alkylating ability under the conditions employed. Compounds 7 to 10 would therefore also be expected to show alkylating properties under those conditions. Furthermore, compound C, which cannot generate reactive methylating species, showed essentially no alkylating activity in this assay and was inactive against the B16 melanoma. Table VI illustrates results for the non-heteroaryl compounds which are not part of the present invention. The data in Table VI supports the hypothetical mechanism described herein but the capacity to generate a reactive intermediate by direct attack of a nucleophile, as depicted herein, cannot be ruled out. It seems likely that the facility of these compounds to act as antineoplastic agents involves complex kinetics since two modes of activation are possible and may compete with each other. Furthermore, one cannot rule out the importance of pharmacodynamic mechanisms in the antitumor measurements.

Claims: A compound of the formula: wherein R₁ is an alkyl of 1-6 carbon atoms, benzyl, phenyl, or phenyl substituted by halogen, alkoxy of 1 to 4 carbon atoms, alkyl of 1 to 4 carbon atoms, amino or carbonyl substituents, or -RN(R')₂ wherein R and R' are each independently an alkyl of 1 to 4 carbon atoms, and R₂ is a heteroaryl substituent, in which the heteroatom is sulfur, oxygen, nitrogen, or a combination thereof; each A is a substituent independently selected from the group consisting of hydrogen, alkyl of 1-4 carbon atoms, alkoxy of 1-4 carbon atoms and halogen; and n is 1, 2 or 3. The compound of claim 1 wherein R₁ is alkyl of 1 to 6 carbon atoms; R₂ is an aromatic heterocycle and each A is a heterocycle substituent independently selected fromm the group consisting of hydrogen, alkyl of 1-4 carbon atoms and halogen; and n is 1, 2 or 3. The compound of claim 1 or claim 2, wherein R₂ is a 5-membered unsaturated ring. The compound of claim 3, wherein R₂ is selected from thienyl, isoxazolyl and pyrazolyl. The compound of claim 2, wherein R₂ is quinolinyl. The compound of any of claims 1 to 5, wherein A is an alkyl of 1-4 carbon atoms. The compound of any of claims 1 to 5, wherein n is 2, one A is halogen and the other A is alkyl of 1-4 carbon atoms. The compound of any preceding claim wherein R₁ is methyl. The compound of claim 8, wherein R₂A n is selected from 2-thienyl, 3,5-dimethylisoxazolyl, 5-chloro-1, 3-dimethylpyrazolyl and 8-quinolinyl. A process for producing a compound of the formula: wherein R₁ is an alkyl of 1-6 carbon atoms, benzyl, phenyl, or phenyl substituted by halogen, alkoxy of 1 to 4 carbon atoms, alkyl of 1 to 4 carbon atoms, amino or carbonyl substituents, or -RN(R')₂ wherein R and R' are each independently an alkyl of 1 to 4 carbon atoms, and R₂ is a heteroaryl substituent, preferably an aromatic heterocycle in which the heteroatom is sulphur, oxygen, nitrogen or a combination thereof, each A is a substituent independently selected from the group consisting of hydrogen, alkyl of 1-4 carbon atoms alkoxy of 1-4 carbon atoms and halogen and n is 1, 2 or 3 wherein an N-methyl-N-sulphonyl hydrazine of the formula wherein A, R₂ and n are as defined above, is reacted with a compound of the formula: wherein R₁ is as defined above, preferably in the presence of an organic base and a solvent, and in which the reagents are preferably reacted in about equimolar proportions. A process according to claim 10 in which the N-methyl-N-sulphonyl hydrazine is produced in a preliminary step by the reaction of a sulphonyl chloride of the formula: A n R₂SO₂Cl wherein A, R₂ and n are as defined in claim 10 with methyl hydrazine, preferably in an organic solvent, e.g. tetrahydrofuran, the sulphonyl chloride and methyl hydrazine preferably being supplied in a molar ratio of about 1:2. A process according to any of claims 10 and 11 in which the product is a compound according to any of claims 1 to 9. Use of a compound according to any of claims 1 to 9 in the manufacture of a composition for use in a method of treatment, preferably for inhibiting tumour growth. An antineoplastic composition comprising an antineoplastically effective amount of a compound according to any of claims 1 to 9 and a pharmaceutically acceptable carrier.

Inventors: HRUBIEC, ROBERT T., SARTORELLI, ALAN C., SHYAM, KRISHNAMURTHY
Applicants: YALE UNIVERSITY
Application year: 1988
Main classification: C07C311
IPC codes: A61K31, C07D261, C07D215, C07D231, C07D521, A61P35, C07D333