IE83632B1 - 10,11-methylenedioxy-20(RS)-camptothecin and 10,11-methylenedioxy-20(S)-camptothecin analogs - Google Patents

Description

TITLE OF THE INVENTION ,11-METHYLENEDIOXY-20 (RS) — CAMPTOTHECIN AND ,11-METHYLENEDIOXY-20 (S) — CAMPTOTHECIN ANALOGS This application is a Continuation-in-Part of U.S. patent application 07/407,779 filed September 15, 1989, and a Continuation-in-Part of U.S patent application 07/511,953, a continuation of U.S. patent application 07/038,157 abandoned, both of which are incorporated—herein-by-reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to methods for making camptothecin analogs which are useful as antitumor agents. More specifically, the invention is directed to water-insoluble and water-soluble derivatives of 10,11-methylenedioxy-20(RS)- camptothecin and 10,11—methylenedioxy-20(S)—camptothecin. These compounds are collectively referred to as 10,1 1—MDOCPT below.

Discussion of the Backqround Camptothecin is a pentacyclic alkaloid initially isolated from the wood and bark of Camptotheca acuminata by Wall et al (M.E. Wall, M.C. Wani, C.E. Cook, K.I-I. Palmer, A.T. McPhaiI, and G.A. Sim, J. Am. Chem. Soc., 942388 (1966)).

Camptothecin is highly biologically active and displays strong inhibitory activity toward the biosynthesis of nucleic acids. Additionally, camptothecin exhibits potent antitumor activity against experimentally transplanted carcinoma such as leukaemia L—l2l0 in mice or Walker 256 tumor in rats.

Several methods for the synthesis of camptothecin and camptothecin analogs are known. These synthetic methods include (i) methods in which naturally occurring camptothecin is synthetically modified to produce a number of analogs and (ii) totally synthetic methods.

U.S. Patents 4,604,463; 4,545,880; and 4,473,692 as well as European Patent Application 0074256 are examples of the former type of synthetic strategy. Additional examples of this strategy can be found in Japanese Patents 84/46,284; 84/ 51,287; and 82/1 16,015. These methods require naturally occurring camptothecin which is difficult to isolate and hence these methods are not suitable for the production of large quantities of camptothecin or analogs.

Examples of a variety of totally synthetic routes to camptothecin and camptothecin analogs can be found in the following references: Sci. Sin. gEngl. Ed 1, 21 (1), 87-98 (1978); Fitoterpapia, 45(3), 87-101 (1974); Yakugaku Zashi, 92(6), 743- 6 (1972); J. Org. Chem, 40(14), 2140-1 (1975); Hua Hsueh Hsueh Pao, 39(2), 171-8 (1981); J. Chem. Soc., Perkin Trans 1, (5) 1563-8 (1981); Heterocycles, 14(7), 951-3 (1980); J. Amer. Chem. Soc., 94(10), 3631-2 (1972); J. Chem. Soc. D, (7), 404 (1970) and U.S. Patent 4,031,098.

Synthetic studies directed to camptothecin analogs have also been conducted by the present inventors and are disclosed in J. Med. Chem., 23(5), 554-560 (1980); J.

Med. Chem., 29(6), 1553-1555 (1986) and J. Med. Chem., 29(11), 2358-2363(1986) for example.

Water—solubility is an important criterion in developing potential antitumor compounds for pharmaceutical use. Most camptothecin analogs known in the art have relatively poor water-solubility. A need exists for additional camptothecin compounds showing high anti—tumor activity and for water-soluble camptothecin analogs and methods for preparing the same.

SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide methods for making camptothecin analogs containing the 10,11-methylenedioxy moiety.

A further object is to provide methods for making camptothecin analogs which exhibit high cytotoxic activity and which can be readily prepared.

These and other objects which will become apparent from the following specification have been achieved by the process of the present invention and the compounds produced thereby.

More specifically, the invention is directed to methods for making compounds which are derivatives of ,11—methylenedioxy—20(RS)—camptothecin (also called l0,l1—MDO—20(RS)—CPT) and 10,1l—methylenedioxy—20(S)— camptothecin (also called 10,11-MDO—20(S)—CPT) which are highly active camptothecin analogs. to © BRIEF DESCRIPTION OF THE DRAWING A more complete appreciation of the invention and many of the attendant advantages thereof will be obtained as the same becomes better understood by reference of the following detailed description when considered in connection with the accompanying drawing, wherein: Figure 1 shows the structure of CPT and derivatives thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS ,1l—MDO-20(S)—CPT is an extremely potent camptothecin analog and is one of the most potent inhibitors of the enzyme topoisomerase I known. 10,1 l—MDO— (S)—CPT is highly active in such mi cytotoxicity tests as the 9KB and 9PS tests and demonstrates ED50 values equal to or more potent than camptothecin itself. 10,11- MDO—20 (S)—CPT is also very potent in the L-1 210 leukemia iL\I_iv_o life prolongation assay. The synthesis of 10,1 l—MDO—20 (RS)—CPT is known and described in Wani et al, J. Med. Chem., 29 (1 1), 2358—2363 (1986) and in U.S. 4,894,456.

Analogs of camptothecin have been prepared, all of which contain the 10,] l- methylenedioxy moiety. The structures of these compounds are shown below.

In the structure shown above, R is N02, NH2, N3, hydrogen, halogen (F, Cl, Br, 1), COOH, OH, O—C1.3 alkyl, SH, S-C1.3 alkyl, CN, CHZNH2, NH—C1.3 alkyl, CH2-NH—C1_3 alkyl, N(C1.3 alkyl)z, CH2N(C1_3 alkyl)2, 0-, NH- and S—CH2CH2N(CH2CH2OH)2, CH2CH;;_CH2N(CH2CH2OI-D2, 0-, NH- and S—CH2CH2N(CH2CH2CH2OH)2, 0-, NH-and S—CH2CH2CH2N(CH2CH;CH2OH2)2, 0-, NH- and S—CHzCH2N(C1.3 alkyl)2, O—, NH- and S—CH2CH2CH2N(C1_3 alky1)g, CHO or C1.3 alkyl. Preferred compounds are those in which R is halogen, nitro or amino. The compound in which R is a chlorine atom is particularly preferred.

Z in the structure shown above is H or C1_g alkyl with the proviso that R and Z are not both hydrogen. Preferably, Z is H.

The structure shown above is understood to represent all isomers having the chemical structure indicated. The structure shown above, therefore, represents both ,1 l—MDO—20(S)-CPT and 10,1 1—MDO—20(RS)-CPT compounds.

Compounds having the structure shown above are generally prepared by first synthesizing 10,1 l—MDO—20 (S)—CPT or 10,11-MDO—20(RS)—CPT in which Z is hydrogen or C1.g alkyl. The synthesis of 10,1 1—MDO—20(RS)-CPT compounds in which Z is hydrogen or C1-g alkyl is possible by means of a Friedlander condensation reaction between an appropriately substituted tiicyclic compound representing rings C, D and E of the camptothecin structure with an ortho—amino benzaldehyde or ketone. Friedlander condensation with an ortho—amino benzaldehyde produces com- pounds in which Z is hydrogen. Condensation using corresponding oItho—amino ketones produces compounds in which Z is C1_g alkyl. Synthesis of the 10,1 1—MDO- (RS)-CPT is fully described in U 8. 4,894,456 incorporated herein by reference for a complete description of the synthesis of this starting compound. The synthesis of ,11—MDO-20(S)— CPT is described in U.S. application serial no. 07/511,953. This application is incorporated herein by reference to provide a complete description of the synthesis of the 10,11-MDO—20(S)-CPT starting compounds in which Z is hydrogen or C1_g alkyl.

The 9—substituted-10,1 1—MDO—20(RS)-CPT and 9-substitutedl0,1l—MDO— (S)—CPT compounds listed above can be synthesized from the 10,11-MDOCPT starting materials described above by preparing a diazonium salt at the 9—position. To prepare the diazonium salts, 10,1 l—MDO—20(S)—CPT or 10,1 1—MDO—20(RS)-CPT is nitrated to form the corresponding 9-nitro compound. This nitro compound is then reduced to form the corresponding 9—amino compound which is used to prepare the diazonium salt.

Using known mixtures of H2804 and HNO3 and standard nitration reaction conditions for the nitration of camptothecin (CPT) itself, one obtains a mixture of the 12-nitro and 9—nitr0—camptothecin analogs with the l2—nitro analog present in considerable excess. A structure analysis of 10,1 1—l\/fl)O—20(S)—CPT and 10,11—MDO— (RS)—CPT reveals that the 9- and 12—positi0ns are available for nitration and the ,11—methylenedioxy group appears to exhibit an analogous electronic influence on both the 9- and 12- positions. An analysis of the electronic and steric environments on the potential nitration positions of 10,11— leads to the expectation that both 10,ll—MDO—20(S)—CPT and lO—ll—MDO— O(RS)—CPT will nitrate in a manner similar to camptothecin itself and provide an excess of the l2—nitro analog.Quite unexpectedly,it was found that nitration of 10,ll—MDO—20(S)— CPT and 10,11-MDO-20(RS)-CPT gives substantially the 9—nitro—lO,11—MDO—analogs with only trace amounts of the l2—nitro—lU,ll—MDO analogs. The present method, therefore, provides a surprisingly effective procedure for preparing the 9~nitro—10,ll—MDOCPT analogs in high yield regioselectively.

The nitration reaction may be conducted using standard conditions for the nitration of aromatic compounds, and is generally conducted by dissolving/suspending the lO,1l¥ MDOCPT in concentrated sulfuric acid with cooling and stirring followed by the addition of a slight excess of concentrated nitric acid. After stirring for a period of time sufficient to substantially complete the reaction, the solution is poured into water, ice or a ice/water mixture to provide the desired 9~nitro—lO,1l—MDOCPT compound.

Purification can be effected by standard extraction and recrystallization processes.

The 9—nitro-lO,l1—MDOCPT may then by catalytically reduced using hydrogen and a hydrogenation catalyst such as platinum, or other conventional palladium, etc., hydrogenation reactions. Preferably, the hydrogenation catalyst is present on an inert support such as powdered carbon. Reduction of the 9—nitro analog to the 9—amino analog is conducted using standard hydrogenation solvents and hydrogen pressure conditions. Generally, the nitro compound is dissolved/ suspended in ethanol and contacted with a hydrogen atmosphere.

The concentration of catalyst and of the nitro compound in the solvent is not critical. Concentrations of the nitro compound from about 1 mg/ml to 3 mg/ml may be used with catalyst concentrations ranging from about 20-100 wt.%. The preferred solvent is absolute ethanol although other conventional inert solvents may be used.

The hydrogenation reaction is generally conducted at ambient temperature although temperatures above or below ambient temperature may be used so long as the camptothecin analog is not decomposed. Hydrogenation reaction times vary with the amount of nitro compound to be hydrogenated and can be easily determined by one skilled in the art. Generally, reaction times ranging from 2-30 hours are sufficient to hydrogenate 9-nitro—lO,ll—MDOCPT.

Although catalytic hydrogenation is a preferred reduction method, other known chemical reductions such as F8804/NH4OH, Sn/HCl, etc. may also be employed to reduce the nitro group to an amino group.

The formation of diazonium salts is a general reaction undergone by primary aromatic amines upon treatment with sodium nitrite in acidic solution. Accordingly, the 9—amino— lO,ll-MDOCPT can be treated with sodium nitrite in acid solution to form the corresponding diazonium salt. These diazonium salts are then reacted with nucleophiles or free (N2) The overall reaction radicals to generate nitrogen gas and the desired 9- substituted—l0,l1-MDOCPT compound. the sequence is shown in scheme 1 below. In the scheme, diazonium salt is shown as structure II where the counter anion X is derived from the acid HX.

O / \.

» I NIINO2 O \ X 03? 1 N2"? Z I II Raagant O / /N_ / _ Bmmd1na.&_,__... < y \! I I f O/’N /// /0 Scheme 1 Non—limiting examples of suitable acids and reaction conditions to prepare a variety of 9—substituted—lO,ll- MDOCPT compounds are shown in Table A.

DJ ‘J! gfixam Tehléifl Other Reagents and Conditions R in Product 11; Additional lO,1l—MDOCPT compounds can be prepared by further reactions on the compounds shown in Table A or by analogous reactions. For example, the compound in which R is ethyl (Cfifi) or propyl (Cfih> can be prepared by a reaction analogous to Example 14 using the reagent (C2Hg4Sn or (C3Hfi4Sn in place of (CHfi4Sn. The compounds in which R is CN can be readily reduced by catalytic hydrogenation to obtain the compound in which R is Cflfiflb by hydrogenation processes analogous to the hydrogenation of 9-nitro~lO,ll— MDOCPT to 9—amino-lO,ll—MDOCPT discussed above or other known reduction reactions.

Alkylation reactions of compounds in which R is OH, SH, NH3 or CH2NHg yields compounds in which R is O-C14 alkyl, S- C14 alkyl, NH‘C1g alkyl or CH2NH—C14 alkyl. Dialkylation of the nitrogen—containing substituents is also possible to yield N(C14 alkyl)2 and CH2N(Cy3 alkyl)2 substituents as R.

Alkylation may be accomplished, for example, using C1-C3 alkyl halides or tosylates (OTs). Preferred alkyl halides are the C1-C3 alkyl chlorides and bromides. If desired, a base such as a tertiary amine may be addedto facilitate the alkylation reaction.

It is possible to incorporate additional nitrogen and oxygen atoms into the substituent R by means of alkylation reactions.

For example, alkylation with a reagent having the formula (C14 alkyl)2N-CHZCHZ-X or (C14 alkyl)2N-CH2CH2CH2-X, where X is halogen or OTs yields the correspondingly alkylated products containing the di-C14 alkylaminoethyl or di—C14 alkylaminopropyl group. In a similar manner, introduction of an oxygen atom is possible using alkylating agents having the formula (HOCH2CHfl2N"(CH2)}3‘X and (HOCH2CH2CHfl2N—(CH2)}3—X to provide the corresponding diethanolaminoethyl, diethanol aminopropyl, dipropanolaminoethyl and dipropanolaminopropyl groups. It may be necessary to protect the hydroxyl group in these latter alkylating agents using standard hydroxyl protecting groups such as THPO—. These hydroxyl protecting groups can be conveniently removed or deprotected after alkylation by treatment with mild aqueous acid.

It has also been discovered that water-soluble analogs of lO,ll—MDOCPT can be prepared by opening the lactone ring of 10,1l—MbOCPT compounds to form water—soluble salts. These new derivatives exhibit substantially improved water- solubility and retain a high level of cytotoxicity.

The interaction of pharmaceutical compounds with biological systems is highly specific and intimately related to the three—dimensional structure of a compound and the chemical functionality present on the pharmaceutical compound. It is well known in the pharmaceutical art that structural changes as simple as the use of an opposite enantiomer can result in complete loss of biological activity and in some instances even opposite biological activity. Surprisingly, it has been discovered that it is possible to hydrolyze the lactone ring of 10,11-MDOCPT and yet retain~substantial biological activity while also enhancing water—solubility.

The open lactone compounds obtained using the methods of the present invention have the structure shown below where R and Z have the same definition as given above for the closed lactone compounds and further Z and R may both be hydrogen.

The water—soluble analogs obtained using the methods of the present invention are prepared by hydrolyzing the lactone ring of lO,ll—MDOCPT or a 9—substituted-10,ll-MDOCPT by utilizing one equivalent of an l\J L/I aqueous alkali metal hydroxide. The hydrolysis is preferably carried out in an aqueous solution. The resulting product is the alkali metal salt of 9~substituted~lO,11—MDOCPT in which the lactone ring has been opened to form the corresponding hydroxyl and carboxylate functional groups, as shown below, where M+ is a monovalent metal cation.

Preferred alkali metal hydroxides are potassium hydroxide and sodium hydroxide, with sodium hydroxide being particularly preferred.

Obviously, alkali metal hydroxide concentrations above or below one equivalent may be used in the present process.

Concentrations below one equivalent result in incomplete formation of the metal salt.

The incomplete formation of the camptothecin salt provides a convenient purification method. Unreacted camptothecin (closed lactone form) is only slightly soluble in water and can be filtered off from the aqueous solution containing the camptothecin sodium salt in solution. This provides a convenient method for separating and purifying camptothecin salts.

The hydrolysis reaction may be conducted at any temperature which allows adequate reaction of the 10,11- MDOCPT and alkali metal hydroxide so long as the temperature is sufficiently low to prevent decomposition of the starting materials. Suitable temperatures are from about 5—50°C with preferred temperatures being approximately room temperature.

In the hydrolysis reaction, the 10,11-MDOCPT is generally, but not necessarily suspended in a suitable solvent such as methanol or aqueous methanol and treated with aqueous alkali metal hydroxide. To increase the rate of reaction, the reaction mixture may be gently heated. After cooling, the lO,ll—MDOCPT metal salt may be isolated by standard recrystallization of chromatographic processes following removal of the methanol and water solvents. Any water miscible solvent conventionally used with camptothecin analogs may be used instead of methanol.

Alkali metal salts of 9- substituted-10,ll—MDOCPT compounds may also be prepared by (open lactone compounds) analogous reactions. For example, 9—nitro-10,ll~MDOCPT, 9- amino—10,ll—MDOCPT, 9—chloro—lO,l1—MDOCPT, 9—amino~lO,ll— MDOCPT or any other 9-substituted—10,ll—MDOCPT derivative may also be hydrolyzed by a process analogous to the process described above for l0,1l—MDOCPT to provide the corresponding monovalent metal salts of these derivatives.

Water-soluble derivatives of lO,l1—MDOCPT can also be prepared by reacting the amino group of 9—amino—lO,ll—MDOCPT with appropriately protected amino acids and peptides, C440 saturated or unsaturated carboxylic acid anhydrides, or the corresponding ester—acid halide derivatives. For example, 9- amino—lO,ll—MDOCPT may be reacted with the carboxylic acid group of an d—amino acid to give compounds having the structure shown below: in which Z is as defined above and R is the group —NHCOCHR1NR%9, where R1 is the side-chain of an d-amino acid, preferably the side chain of a D or L—isomer of one of the naturally occurring amino acids, preferably one of the commonly occurring amino acids, and R2 and R3 are, independently, hydrogen or a lower alkyl group having 1-6 carbon atoms. Additionally, R3 may be a peptide unit containing 1-3 amino acid units bonded to the nitrogen atom through a peptide bond. These water-soluble analogs, therefore, contain from 1-4 peptide units bonded to the 9- amina nitrogen atom by means of a peptide bond. Obviously, amino acids which are not naturally occurring may also be used to prepare water-soluble 9—amido-lO,1l—MDOCPT derivatives so long as the amino acid has a carboxylic acid, acid halide or other reactive acyl functionality to form the required peptide bond with the 9-amino group of 9—amino— ,ll—MDOCPT. Other, preferred side chains R1 are alkyl and aralkyl groups containing 2-20, preferably 2-10 carbon atoms.

Generally, these amino acid and peptide-containing derivatives are prepared using amino acids and peptides in which reactive functional groups such as amino groups and carboxylic acid groups are protected using standard amino acid and carboxylic protecting groups. For example, when preparing a derivative from an amino acid such as glycine, one can protect the amino group of glycine by reaction with tBOC chloride to prepare the reactive tBOC—protected amino acid. Appropriately protected amino acids are also available commercially. The protected amino acid is reacted with 9- amino—lO,1l-MDOCPT and the tBOC group is then removed to give the water—soluble salt of the 9- glycinamido derivative, for example.

If desired, free amino groups on the amino acids or peptides may be derivatized by known nitrogen alkylation reactions, i.e., reaction with alkyl halides, to provide mono or dialkylamino acid amido derivatives as shown above {R2 and/or R3: alkyl). Preferably, free amino groups are derivatized to form CL3 mono or dialkylamino groups.

Dibasic amino acids such as arginine, histidine, lysine, etc., and dicarboxylic amino acids such as aspartic acid, glutamic acid, etc., may be used for one or more of the amino acids in the amino acid or peptide derivatives described above. If desired, standard addition salts may be prepared by reacting the free amino groups of any amino acid with a mineral acid such as HCl, HBr, H3PO4 or organic acids such as malic, maleic or tartaric acids. Likewise, free carboxylic acid groups or any amino acid may be derivatized by the formation of monovalent metal cation salts, ammonium salts or quaternary ammonium salts by the addition of ammonia or amines. monovalent metal hydroxides, Quaternary ammonium salts may be formed with primary, secondary or tertiary amines in which the nitrogen atom of the amine contains 1, 2 or 3 lower alkyl or substituted lower alkyl groups.Substituted lower alkyl groups containing one or more hydroxyl groups are preferred. Sodium salts, triethylammonium and triethanol ammonium salts are particularly preferred.

Other water—soluble derivatives can also be prepared by reacting 9—amino—lO,ll—MDOCPT with a C440 saturated or unsaturated acid anhydride, the corresponding ester-acid halide or other reactive acyl derivatives to provide analogs having structure I in which R is NHCO—C24-alkylene-X and NHCO—C24—alkenylene—X where COOH. The reaction is optionally carried out in a suitable solvent and produces the corresponding half acid. For example, reaction of 9— amino—lO,ll—MDOCPT with glutaric anhydride gives the 9- glutaramide half acid.

Likewise, reaction of 9—amino—lO,ll— MDOCPT with the C14 ester-acid halide corresponding to glutaric anhydride results in the 9—glutaramide half acid ester. Conventional hydrolysis of the ester produces the half acid. Water solubility may be imparted in each case by reaction with one equivalent of any of the bases noted above.

The reaction of 9—amino—lO,ll—MDOCPT with the anhydride or other reactive acyl compound is preferably carried out in the presence of a weak base such as a tertiary amine to facilitate the formation of the product amide. Suitable amines include cyclic amines such as pyridine as well as lower alkyl tertiary amines.

The free acid group of the amide half acid may be further coupled with a suitable alkylene diamine (NHR2-(CH2)n—NR2R3) to give amino amides in which the R group in structure I is —NH—A' ~NR2—(CH2)n— NRZR3, where n = l~lO, preferably 2-6, and A’ is a Caloacyl-alkylene—acyl or C440 acyl-alkenylene—acyl group, i.e., R is NHCO—C24-alkylene—X or NHCO-C24- alkenylene—‘X where x is coon or CONR2—(CH2)n—NR2R3. For example, the reaction of 9—glutaramido-10,ll-MDOCPT with a suitable diamine such as 3—(dimethylamino)-l—propylamine gives the corresponding amino acid amide as shown below. \;xx, CH3 _ g /’ 1 04 11‘—,MQQC_}?T—-NHC0: ;CQNHCHéCH2CHzN Acid and base addition salts of these derivatives may also be prepared in a manner analogous to that described above.

In another embodiment, water—soluble urea and urethane analogs can be prepared by reacting 9—amino—lO,ll~MDOCPT with phosgene followed by reaction with an appropriate diamine or tertiary-amino alcohol to give compounds having the formula I in which R is —NHCO—B—(CHfln—NR%9, where B is oxygen or NH, and compounds in which R is (CH2).

NHCQ—N N~R2 \ / (C.IIz)Y where m + y 4 3—6 and n, R2 and R3 are as defined above.

Suitable diamines are primary and secondary straight- chain, branched or cyclic diamines containing 3-15 carbon atoms. Examples of straight—cFained and branched diamines include diaminoethane, 1,2~ and l,3—diaminopropane, l,4— diaminobutane, etc. Examples of cyclic diamines included pyrazolidine, imidazolidine, piperazine, etc. Preferred diamines are diamines in which one of the amino groups is derivatized to form a di-lower—alkyl—amino group such as, for example, NH2CHflHfiCH2N(CH2CHflg. The reaction of 9—amino— lO,ll—MDOCPT with phosgene followed by a diamine is represented below. i _ *~9—N=C=O 9~amino~10,1l—MDOCPT + C0(C12? 1°'11 "DOCP1 fit 2:: L.

/ / EL it Tertiary—amino alcohols for the preparation of urethane analogs include N,N—di—C14—alky1amino alkanols prepared from straight chain or branched amino alkanols having 2-10 carbon atoms, for example, N,N—diethyl—aminoethanol.

Water soluble standard acid and base addition salts can be prepared from the urea and urethane analogs in a manner similar to that described above for other amino and carboxylic acid group—containing analogs.

Preferred derivatives prepared using the methods of the present invention are 10,11—MDOCPT analogs having glycinamido, succinamido, glutaramido, (4—methy1piperazino) carbonylamino, N,N-dimethylaminopropylamido—glutaramido and (N,N—diethylaminoethoxy)carbonylamino substituents at the 9- position and the water soluble salts thereof.

The salts prepared using the methods of the present invention exhibit substantially improved water-solubility relative to conventional camptothecin analogs and may be formulated into solid and aqueous pharmaceutical compositions by conventional methods. The compounds of the present invention are active in standard cytotoxicity tests and are inhibitors of topoisomerase I.

The 10,11—methy1enedioxy (MDO) group confers striking and unexpected improvements on the in vitro and in vivo been shown by Jaxel et al. (loc. cit.) to be very well correlated with in vivo anti—tumor and anti—leukemic activity.

In contrast, a compound with quite similar structure, ,ll-dimethoxy—20(RS)—CPT, is totally inactive, Wani et al., J. Med. Chem., 92: 2360 (1986).

Unlike, 10,11- dimethoxy—éO(RS)-CPT, the 10,ll—MDO moiety is held rigidly in the plane of ring A of CPT (See the structure in Figure 1), and this is thought to contribute to the additional biological activity unexpectedly noted with all of these compounds.

Table B shown below shows the potent topoisomerase I inhibitory activity of CPT and some analogs. The cleavable complex assay was performed according to the method described in Hsiang, Y—H. et al., J. Biol. Chem., 260:l4873— ). The cleavable complex assay correlates well with infyiyo anti—tumor activity in animal models for camptothecin 49:4385—4389 4921465-1469 analogs.See Hsiang et al., Cancer Research, (1989) (1989). and Jaxel et al., Cancer Research, ** Ecm is the concentration of a compound which gives.50% topoisomerase I inhibition as revealed by cleavable complex formation. All ECW values represent the mean of several independent assays; all values are normalized with respect to #9, 20(S)—CPT, which was always assayed as a control.

The compounds obtained using the methods of the present invention are active against murine tumors, such as lymphocytic leukemia L—1210, RAW117—H1O lymphosarcoma and K1735—M2 melanoma. Activity in one or more of these tumor tests has been reported to be indicative of anti—tumor activity in man (A. Goldin et al., in Methods in Cancer Research, ed. V.T. DeVita Jr. and H. Busch, 16: 165, Academic Press, New York, 1979).

In tumor histioculture studies (See Table C) using human cancers obtained by surgery or biopsy, the compounds of the present invention demonstrate significant activity, measured as inhibition of tumor cell proliferation during treatment with the compounds of the present invention. As used herein, the term "cancer" is synonymous with the terms "malignant tumor" and more generally "tumor". The data shown in Table C demonstrate the activity of the present compounds against human colon cancer, which is well known to be a very resistant cancer to chemotherapy. See H.L. Davis, Chemotherapy of Large Bowel Cancer, Cancer (Phila.) 50: 2638-2646 (1982); J.R. Neefe and P.S. Schein, Chapter 43: The Management of Disseminated Large—Bowel Cancer in Principals of Cancer Treatment, page 402, ed. S.K. Carter, E. Glatstein and R.B. Livingston, McGraw—Hill Co., 1982; K Mekhail—Ishak, Cancer Research, 49: 4866 SIMILAR 3869 (1989) 49: 1148-1153 and P.J. Ferguson and Y.C. Cheng, Cancer Research, (1989).

I3fl2l£LJ£i:_lflfl1&H_£llLQN;1lHfl2RiHXSIXKZCQLTURE Inhibition of Cell Proliferation Name‘. at it I V it/"C50 (Ltsrrmli) (8)-CPT ~0_02 — in",11914131)(s):c?zi1*3*’3"l‘"l" H0 003 ,11~MDo—2o{s)~CPT, N.'a'+ saw —«0:OO5 9—NH2~1O,11-MDO-20(S)~CPT "(L002 ,;L1—MDO—20(RS)-CPT ~0 005 1o,11—1m.o—2o(Rs_)—cPT,‘Na' SALT ~0'01 so 9"NH2",10r11"MDO"‘29(‘R3)_;‘I_CBT,. «0 005 ~0.01 ~'NH2‘¥’1'o,11—MDo~«2o(R1s)‘¥4c'trp, Na‘ SALT * Abbreviations CPT = Camptothecin MDO 2 Methylenedioxy ** Icm: concentration of compound required to inhibit by [H]thymidine into DNA % the incorporation of Inhibition of tumor cell proliferation was performed in vitro on human colorectal tumors obtained from surgery or (Proc. Nat'l.4Acad. biopsy, as described by Vescio et al Sci. USA 84:5029—5033, 1987) with the following modifications: Tumors were cultured 1 day prior to drug addition; tumors were exposed to compounds for 24 hours, washed, and then exposed to [H]thymidine for 3 days.

The compounds obtained using the methods of the present invention exhibit antitumor activity against human colon cancer, which is known to exhibit de novo drug resistance, and thus be difficult to treat chemotherapeutically.

Therefore, it is believed that the compounds obtained using the methods of the present invention will be active against a wide spectrum of mammalian (including human) cancers such as cancers of the oral cavity and pharynx (lip, tongue, mouth, pharynx), esophagus, stomach, small intestine, large intestine, rectum, liver and biliary passages, pancreas, larynx, lung, bone, connective tissue, skin, breast, cervix uteri, corpus endometrium, ovary, prostate, testis, bladder, kidney and other urinary tissues, eye, brain and central nervous system, thyroid and other endocrine gland, leukemias (lymphocytic, granulocytic, monocytic), Hodgkin's disease, non—Hodgkin's lymphomas, multiple myeloma, etc. Obviously, the compounds obtained using the methods of the present invention may be used to treat other cancers not specifically named so long as antitumor activity is demonstrated by the compounds in the particular cancer.

Pharmaceutical compositions containing the camptothecin derivatives obtained using the methods of the present invention may also be prepared. There may be included as part of the composition pharmaceutically acceptable binding agents, carriers and/or adjuvant materials. The active" materials can also be mixed with other active materials which do not impair the desired action and/or supplement the desired action. The active materials obtained using the methods according to the present invention can be administered by any route, for example, orally, parenterally, intravenously, intradermally, subcutaneously, or topically, in liquid or solid form.

For the purposes of parenteral therapeutic administration, the active ingredient may be incorporated into a solution or suspension. The solutions or suspensions may also include the following components: a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl parabens; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose. The parenteral preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic.

Another mode of administration of the compounds obtained using the methods of this invention of this invention is oral. Oral compositions will generally include an inert diluent or an edible carrier. They may be enclosed in gelatin capsules or compressed into tablets. For the purpose of oral therapeutic administration, the aforesaid compounds may be incorporated with excipients and used in the form of tablets, elixirs, troches, capsules, suspensions, syrups, wafers, chewing gums and the like.

The tablets, pills, capsules, troches and the like may contain the following ingredients: a binder such as microcrystalline cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent corn starch and the like; a such as alginic acid, Primogel, K) K/I lubricant such as magnesium stearate or Sterotes; a glidant such as colloidal silicon dioxide; and a sweetening agent such as sucrose or saccharin or flavoring agent such as peppermintf methyl salicylate, or orange flavoring may be added. When the dosage unit form is a capsule, it may contain, in addition to material of the above type, a liquid carrier such as a fatty oil. Other dosage unit forms may contain other various materials which modify the physical form of the dosage unit, for example, as coatings. Thus tablets or pills may be coated with sugar, shellac, or other enteric coating agents.A syrup may contain, in addition to the active compounds, sucrose as a sweetening agent and certain preservatives, dyes and colorings and flavors.

Materials used in preparing these various compositions should be pharmaceutically pure and non—toxic in the mounts used.

As known in this art, dosage values will vary with the specific cancer to be treated, the stage of tumor development, tumor location, weight and physical condition of the patient being treated, etc. Good results should be achieved when the compounds described herein are administered to a subject requiring such treatment as an effective oral, parenteral or intravenous dose of from about O.l to about 100 mg per day per patient. It is to be understood, however, that for any particular subject, specific dosage regimens should be adjusted to the individual need in View of the patients response to treatment with the drug and the professional judgment of the person administering or supervising the administration of the aforesaid compound. It is to be further understood that the dosages set forth herein are exemplary only.

Dosages above or below the range cited above are permissible and may be administered to the individual patient if desired and necessary. The dosages may be administered at once, or may be divided into a number of smaller doses to be administered at varying intervals of time.

Other features of the invention will become apparent from the following descriptions which are given for illustration of the invention and are not intended to be limiting thereof.

EXAMPLES Example l - Synthesis of 9-Amino-10,11-MDOCPT. lO,ll-MDO-20(RS)-CPT and 10,ll-MDO—20(S)-CPT were prepared according to Wani et al., J. Med. Chem.. £2. 2358 (1986) and the process disclosed in U.S. no. O7/511,953. application serial Conversion of 10,ll—MDOCPT to 9-Nitro-10,11-MDOCPT. (332 mg, lO,11—MDOCPT 0.847 mmol) was dissolved/suspended in conc. H2504 (5 mL), stirred and cooled to OOC, and treated over 5 min with conc. HNO3 (25 drops). After 1 hr. the brown solution was poured onto ice/H20 (50 mL) to provide a yellow—orange precipitate which (292 mg). (2 x 50 mL) was collected by filtration Extraction of the filtrate with CHCl3 (83 mg) provided additional material for a total yield of 375 mg (100%).Recrystallization from MeOH/CHCl3 provided a 75% recovery of the title compound as a yellow powder: mp darkening above 2550C with no melting below 350°C: IR vmw (KBr) 3430 (br), 2920, 1741 (lactone), 1654 (pyridone), 1596 (aromatic), 1525 (N02), 1450, 1343, 1242, 1191, 1154, 1043, 928, 785 and 565 cm"5 1H NMR (DMSO-dg) 5 0.87 (t, 3, J = 7 HZ, H-18), 1.85 (m, 2, H-19), 5.21 (S, 2, H-5), 5.41 (S, 2, H-17), 6.52 (S, 2, -OCfl2O—), 7.24 (S, 1, H-14), 7.78 (S, 1, H-12), 8.96 (S, 1, H-7). gonversion of 9-Nitro—10,11-MDOCPT to 9—Amino—10,11—MDOCPT.

A suspension of the nitro compound (139 mg) prepared above and 10% Pd/C (75 mg) in abs EtOH (40 mL) was stirred at ambient temperature under 1 atm H2 for 20 hr. The mixture (Celite) MeOH/CHCl3 and HCl. was filtered and the pad washed profusely with Evaporation of the solvents afforded the crude amine as an orange-brown solid (125 mg, 97%).

Recrystallization from MeOH/CHCl3 gave the title compound as a tan—orange powder (87 mg, 67%), mp darkening above 250°C with no discreet melting below 3500c. 1H NMR (DMSO-d6) 5 0.88 Example 2 — Synthesis of 9—Bromo—10,11-MDO—20(S)—CPT (III, R=Br).

A stirred mixture of 9-amino—10,11—MDO—20(S)~CPT (10.0 mg, 25.5 umol) in 48% aq HBr (0.5 mL) at 0°C was treated with a solution of NaNO2 30.6 umol) (25 ul). (2.1 mg, in H20 cooling source was removed, and after the addition of CuBr (4.0 mg, 35 umol), the brown mixture was heated for 20 min at 80°C. The mixture was cooled and poured over ice (3 g).

The resulting suspension was extracted with several 10 mL portions of CHCI3, and the extract was dried (Na2SO4) and evaporated under reduced pressure to afford an orange-yellow solid (10 mg) containing mostly the title compound III (R=Br) and, to a lesser extent, III (R=H).Purification was effected by flask column (1 g 230-400 mesh Si02, 0.25—1% MeOH in CHCI3) to provide III (R=Br) as a pale yellow solid (3.8 mg) and III (R=H) in later fractions as a cream colored solid (2.0~mg). 300 MHZ 1H NMR (DMSO-d6) 5 0.84 (t, 3, J27 Hz, H—18), 1.82 (m, 2, H~19), 5.24 (s, 2, H-5), 5.39 (s, 2, H-17), 6.36 (s, 2, -OCHZO-), 6.49 (s, 1, 03), 7.24 (s, 1, H- 14), 7.54 (s, 1, H~12), and 8.63 (s, 1, H-7); HRMS: calcd. for CmH1@hO6Br, 470.0114; measured, 470.0115.

Example 3 — Synthesis of 9—Chloro—10,l1—MDO—20(S)—CPT (III, R=Cl).

The intermediate diazonium chloride II (X=Cl) is prepared as in Example 2 except that 39% aq HCl is used.

Similarly, the substitution of CuCl leads to the expected 9- (R:Cl) chloro compound III after chromatography.

Example 4 — Synthesis of 9—Carboxy—10,11-MDO—20(S)—CPT RZCO2 ) .

(III, The diazonium salt II (X=Cl) is prepared as in Example . After filtration of the aq HCI solution, ag HBF4 is added to give a precipitate of II (X=BF4). This salt is combined in a pressure reactor with Pd(OAc)2 and NaOAc in MeCN. Carbon monoxide (1-2 atm) is introduced and the mixture is left for 1 hr at ambient temperature. The mixture is concentrated by evaporation and reconstituted in H20. Crude III (R=CO2H) is isolated by extraction into CHCI3, and purified by further extraction into dilute ag NaHCO3 followed by precipitation with acid.

Example 5 - Synthesis of 9—Formyl-10,ll-MDO-20(S)—CPT (III, ECJQL-T.

The diazonium salt II (X=Cl) is prepared as in Example . The salt solution is treated at room temperature with an aqueous solution of formaldoxime containing CuSO4 and Na2SO} After 1 hr, conc. HCl is added and the intermediate oxime is collected and hydrolyzed to the produce aldehyde III (R=CHO) by refluxing in conc. HCl.

Exampfe 6 — Synthesis of 9—Hydroxy—lO,1l~MDO—20(S)—CPT (III, R:OH).

The intermediate diazonium salt II (X=HSO4) is prepared in a manner analogous to that of Example 2 by using ag H2504 instead of aq HBr. The mixture is then heated at 800C for 1 hr whereby hydrolysis occurred. On cooling, the product III (R=OH) is isolated by extraction into CHCI3.

Example 7 — 9—Cyano—lO,ll—MDO-20(S)—CPT (III, R=CN).

(X=Cl) Example 2 and treated at 200C with CuCN after the pH has The diazonium chloride II is prepared as in been adjusted to 7 with Na2CO3. After 2 hr, the reaction mixture is R) kll extracted with CHCI3. The CHCI3 extract is used to isolate the title compound III (R=CN) by chromatography.

Example 8 - 9-Azido-10,11-MDO—20(S)-CPT (III, R=N3).

The diazonium chloride II (X=Cl) is prepared as described In Example 2. The resulting mixture is treated with an aqueous solution of NaN3, and after 15 min at room temperature, the azide III (R:N3) results as a precipitate.

Centrifugation provides the product as a pale solid which is purified by column chromatography.

Example 9 — 9—Fluoro—lO,ll—MDO-20(8)-CPT (:11, R=%).

The diazonium chloride II (X=Cl) is prepared as before (Example 2), and after filtration the stirred solution is treated at 0°C with a slight excess of HBF4 whereupon salt II (X:BF4) precipitates. After collection and drying, this salt is pyrolized (>/= I200) over 1 hr to afford fluoro product III (R=F). Dark colored impurities can be removed by a flash column chromatography.

Example 10 — 9—Iodo—lO,ll—MDO-20(S)~CPT (III, R=I).

A solution of chloride II (X—Cl, prepared as before, Example 2) in aq HCl is treated with aq KI and heated for l hr. Upon cooling, the mixture is extracted with CHCI3, and the extract concentrated and subjected to column chromatography to provide III (R=I).

Example 11 ‘— lO,1l—MDO-20(5)-CPT (111, R=H).

The solution of diazonium sulfate II (X=HSO4), prepared as in Example 6, is maintained at -100 to O0 and treated with excess hypophosphorous acid (H3PO2). After 1 hr, the unsubstituted product Ill (R=H) can be isolated in nearly pure form by extraction with a few portions of CHCly Example 12 — 9—Mercapto-l0,l1—MDO—20(S)—CPT (III, R=SH).

A diazonium chloride ll (X=Cl) solution, prepared as in Example 2, is treated at 40° with potassium ethyl xanthate (KCS2OEt). The intermediate ethyl xanthate is extracted into CHCl3, and after evaporation of the CHCl3, the xanthate is hydrolyzed with KOH in aq MeOH. The solution is neutralized with conc. HCl and the thiol III (R=SH) isolated by extraction with CHCl3 Example 13 — 9—Methyl~l0,l1—MDO—20(S)—CPT (III, R=Me).

The diazonium tetrafluoroborate salt 11 (X=BFm, prepared as in Example 4, is added to MeCN and to the resulting stirred mixture is added Me4Sn and Pd(OAc)2 at room temperature. After 2 hr, the MeCN is evaporated and the residue partitioned between H20 and CHCI3. The CHCI3 is reserved and the aqueous portion is extracted twice more with CHCI3. From this extract, III (R=Me) is isolated.

Example 14 - 9—Ethyl—10,11—MDO—20(S)—CPT (III, R=Et).

The diazonium tetrafluoroborate salt II (X=BFm, prepared as in Example 4, is added to MeCN and to the resulting stirred mixture is added Et4Sn and Pd(OAc)2 at room temperature. After 2 hr, the MeCN is evaporated and the residue partitioned between H20 and CHCI3. The CHC13 is reserved and the aqueous portion is extracted twice more with CHCl3. From this extract, III (R=Et) is isolated.i Example 15 — Conversion of 9-Amino—10,11—MDOCPT to 9- Glycinamido—10,11—MDOCPT Hydrochloride.

A stirred mixture of the 9—amino compound (186 mg. .457 mmol) and BOC—glycine (150 mg, 0.85 mmol) in pyridine (1 mL) and pm (15 mm was chilled to 0°C and treated with DCC (200 mg, 0.971 mmol). The mixture was warmed to ambient temperature and stirred for 65 hr. The solvents were evaporated and the residue dissolved in MeOH/CHC3. Celite (3 g) was added, the mixture evaporated, and the Celite— dispersed sample placed on a silica gel column (20 g).

Elution (200 mL CHCI3, 500 mL 5% MeOH/CHCI3, 500 mL 12% MeOH/CHCl3) and evaporation of appropriate fractions gave the intermediate BOC-protected derivative (98 mg , 38%). The derivative was treated with chilled conc HCI/dioxane (1:9, 5 mL), and the resulting mixture was stirred at ambient temperature for 5 hr. The solvent was evaporated, the residue sonicated in deionized H20 (50 mL) and filtered (0.45 micron membrane).The clear yellow solution was lyophilized to give an amber gummy solid which on trituration with abs EtOH gave the glycinamide hydrochloride salt as a yellow microcrystalline solid (57 73%), mg, mp darkening above 2300C with no apparent melting below 34000, IR vma. (KBr) 3680-2300 with maxima at 3220, Example 16 — Synthesis of 9—G1utaramido-10,11—MDOCPT Triethanolamine Salt. __________i__i.._.__._ The 9—glutaramido derivative was synthesized from 9- amino—10,ll—MDOCPT by the following method: 'Glutaramido~10,11-MDOCPT.

A stirred suspension of 9—amino—10,11-MDOCPT and glutaric anhydride in pyridine under nitrogen was heated at 95°C for 2 hr. The solvent was removed from the brown solution by high vacuum distillation to give the crude amide as a brown gum. Purification was effected by chromatography through silica gel employing a solvent gradient from 5% methanol/chloroform to 50% methanol/chloroform. Evaporation of the appropriate fractions gave the 9—g1utaramide half acid.

Alternatively, the 9—glutaramido derivative can be prepared by hydrolysis of its ethyl ester which is prepared by the following general method: 9—Amino—lO,ll—MDOCPT in dry N,N-dimethylformamide containing pyridine is reacted at O- lOOC with a slight excess of ethylglutaryl chloride in N,N— dimethylformamide solution. After work—up and chromatography on silica gel, the 9—(ethyl)glutaramide derivative is obtained.

Example 17 — Synthesis of 9-(4—methylpiperazino) carbonylamino—lO,1l—MDOCPT Hydrochloride.

Kii,i,_i__i_l__,,_i__i__,_____________ The title compound was prepared from 9—amino-lO,ll—MDOCPT in the following manner: -{4—Methylpiperazino)carbonylamino—l0,ll—MDOCPT.

—Amino—lO,ll—MDOCPT was added to chloroform (treated with alumina to remove hydroxylic components) containing triethylamine. The resulting solution was treated with phosgene gas and filtered to remove solids. The filtrate containing the intermediate carbamoyl chloride was treated with N—methylpiperazine under nitrogen and left overnight.

The turbid mixture was washed several times with aqueous sodium bicarbonate solution, dried and evaporated to afford the crude title compound. Chromatography on silica gel provided 9-(4—methylpiperazino)carbonylamino-lO,ll—MDOCPT. -(4-Methylpiperazino)carbonylamino—lO,1l—MDOCPT Hydrochloride.

The free base urea obtained above was suspended in methanol and treated with one equivalent of dilute aqueous hydrochloric acid. The methanol was evaporated and the aqueous residue filtered through a membrane filter. The sample was lyophilized to provide the title compound.

Example 18 — Synthesis of 9-(N,N—Diethylaminoethoxy) carbonylamino-10,1l—MDOCPT.

The intermediate 9—carbamoyl chloride was prepared as in the preceding example. The resulting chloroform solution was treated with N,N—diethylaminoethanol under nitrogen.

After standing overnight, the mixture was washed with aqueous sodium bicarbonate solution, dried and evaporated to afford the crude carbamate. Purification by silica gel, chromatography gave the pure title carbamate as the free base.

Example 19 ~ 9—(N,N-Diethylaminoethoxy)carbonylamino—l0,11- MDOCPT Hydrochloride.

The free base from Example 5 was suspended in methanol and treated with one equivalent of dilute aqueous hydrochloric acid. The methanol was evaporated and the aqueous solution filtered (membrane). Lyophilization afforded the water soluble title carbamate.

Example 20 — 10,11—MDO-20(RS)—camptothecin Sodium Salt The title compound was prepared from 10,11—MDO—20(RS)- camptothecin (Wani et al., J. Med. Chem. g9, 2358 (1986)) by hydrolytic action of sodium hydroxide. Thus, 10,11—MDO— (RS)—CPT (77 mg, 0.194 mmol) was suspended in 90% aqueous methanol (30 mL) and treated with 0.1 N aqueous sodium hydroxide Upon heating at 50—60OC for (1.94 mL, 0.194 mmol). to Im h under nitrogen a clear solution resulted which was cooled to ambient temperature and evaporated to dryness. The residue was dissolved in distilled water (2 mL) and filtered (0.45 micron membrane), and the resulting solution evaporated.The residue was recrystallized from ethanol/ether to provide the title compound as a pale yellow solid (53 mg, 65%), mp >‘3o0°c; IR vma,,(KBr) 3400 (br), 2970, 2920, 1640, 1610, 1560-1580, 1497, 1466, 1370, 1246, 1225, 1183, 1030, 1000, 947, 855, 810, 761, 708 and 560~580; 1H NMR (DMSO-dd .85 (t, 3, J = 7 Hz, H-18), 2.09 (m, 2, H-19), 4.74 (ABq, 2, Av = 68 Hz, J = 12, 4 Hz, H-17), 5.12 (S, 2, H-5), 5.64 (dd, 1, J = 4, 7 Hz, 17-OH), 6.17 (S, 1, 20-OH), 7.47 (s, 1, H—14), 7.54 (s, 1, H-9), 7.62 (s, 1, H-12), 8.41 (s, 1, H- Example 21 — 9—Amino—10,11-MDO—20(RS)—Camptothecin Sodium .511; The title compound was prepared by an analogous alkaline hydrolysis of 9—amino—10,11—MDO—20(RS)CPT which was prepared as described above. Thus, a suspension of 9—amino— ,11—MDO-20(RS)CPT in aqueous methanol was warmed with one equivalent of aqueous sodium hydroxide to provide a clear Isolation as above provided the water soluble solution. title compound as an orange-yellow solid.

The synthesis of 10,11—MDO-20(S)—CPT, a starting material for Example 1 is disclosed in J. Med. Chem., 1987, 30: 2317.

Claims (12)

Claims

1. A method for making a 9—nitro 20(S) or 20(RS)-camptothecin which comprises nitrating a 20(8) or 20(RS) — camptothecin having the structure shown below: wherein Z is hydrogen or C1-C3 alkyl. A method for making a 9—amino 20(S) or 20(RS) camptothecin which comprises reducing a 9—nitro 20(8) or 20 (RS) camptothecin made by the method of claim 1. A method for making a 20 (S) or 20 (RS)—camptothccin having the structure shown below: wherein Z is hydrogen or C1_g alkyl, R is N3, hydrogen, halogen, COOH, OH, O—C]_3 alkyl, SH, S—C..3 alkyl, CN, CH2NH2, NH—C1—3 alkyl, CH2—NH-C;.3 alkyl, N(C1.3 alkyl)

2., CH2N(C1.

3.alkyl)2, O-, NH- or S—CH2CH2N (CH2CH2OH)2, O-, NH- or S- CH2CH2CH2N(CH2CH2OH) 2, 0-, NH— or S—CH2CH2N(CH2CH2CH2OH) 2, 0-, NH- or S—CH2CH2CH2N(CH2CH2CH2OH2) 2, 0-, NH— or S-CH2CH;N(C1_3 alkyl) 2, 0-, NH- or S-CH2CH2CH2N(C1_3 alky1)2, CHO, C1-3 alkyl or NHCOCHRINRZR3, where R1 is the side-chain of an on-amino acid and R2 and R3, independently, are hydrogen or a lower alkyl group or R3 is a peptide unit containing 1-3 amino acid units bonded to the nitrogen_ through a peptide bond; NHCO—C2.g—alkylene—X or NHCO—C2.g—alkeny1ene—X, where X is COOH; CONRZ-(CH2)n,- NRZR3, where n = 1-10 and R2 and R3 are as defined above; NHCO—B—(CH2),,,—NR2R3, where B = oxygen or NH; or where m + y = 3-6, with the proviso that R and Z are not both hydrogen which comprises any of steps (a) to (e) set out below: a) alkylating a 9—amino compound made by the method of claim 2; b) forming a diazonium salt from a 9—amino compound made by the method of claim 2 and reacting the diazonium salt with a nucleophile or free radical to form a group R; c) where the group R is CN, optionally reducing it to CHZNHZ; d) where the group R is OH, SH, or CHZNH2, optionally alkylating it; e) reacting the amino group of the 9—amino compound made by the method of claim 2 with a amino acid or peptide, a C4-10 saturated or unsaturated carboxylic acid anhydride or a corresponding ester—acid halide derivative, and optionally forming derivatives of free amino groups of the amino acids or peptides by alkylation reactions or forming derivatives of a free acid group of an amide half acid by coupling with an alkylene diamine.

4. A method for preparing a 20(S) or 20(RS)—camptothecin having the structure shown below: wherein Z is H or C1_g alkyl and R is NHCOCHRINRZR3, where R1 is the side» chain of an oc—amino acid and R2 and R3, independently, are hydrogen or a lower alkyl group or R3 is a peptide unit containing 1-3 amino acid units bonded to the nitrogen through a peptide bond; NHCO—C2.g-alky1ene—X or NHCOC2-g—a1kenylene—X, where X is COOH and n = 1-10, comprising reacting 9—amiI1o- or 9-amino—7—C1.;3 alkyl-10,11—methy1enedioxy—20(S) or 20(RS)— camptothecin made by the method of claim 2 with an amino group- protected amino acid or peptide containing 1-4 amino acid units, a C4-10 saturated or unsaturated carboxylic acid anhydride or with phosgene followed by the reaction with a primary or secondary straight—chain; branched or cyclic diamine or a tertiary-amino. .

5.A method according to any of claims 1-4, wherein the camptothecin is converted into a salt. .

6.A method for preparing a 20(S) or 20(RS)-camptothecin salt having the structure shown below l0 wherein M+ is a monovalent metal cation, R is N02, NH2 or is as defined in claim 3 and Z is as defined in claim 1, said method comprising hydrolyzing the lactone ring in a camptothecin made by the method of any of claims 1 to 4.

7. A method according to claim 1 substantially as hereinbefore described with reference to the examples and/or accompanying drawings.

8. A method according to claim 2 substantially as hereinbefore described with reference to the examples and/or accompanying drawings.

9. A method according to claim 3 substantially as hereinbefore described with reference to the examples and/or accompanying drawings.

10. A method according to claim 4 substantially as hereinbefore described with reference to the examples and/or accompanying drawings.

11.ll. A method according to claim 5 substantially as hereinbefore described with reference to the examples and/or accompanying drawings.

12. A method according to claim 6 substantially as hereinbefore described with reference to the examples and/or accompanying drawings. Tomkins & Co.