Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D487/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00
  • C07D487/12—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00 in which the condensed system contains three hetero rings
  • C07D487/14—Ortho-condensed systems
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
  • C07D401/14—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing three or more hetero rings
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P35/00—Antineoplastic agents
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D471/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00
  • C07D471/12—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00 in which the condensed system contains three hetero rings
  • C07D471/14—Ortho-condensed systems
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/30—Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change

Definitions

• the present invention relates to antitumoural compounds, and in particular to new antitumoural analogs of variolin B and deoxyvariolin B.
• the present invention also relates to synthetic processes, and in particular to synthetic processes for producing both the new compounds of the invention and the known compounds variolin B and deoxyvariolin B, including novel intermediates which form a part of such synthetic processes.
• the present invention relates to novel, previously undisclosed indications of known variolin compounds.
• the variolins are a new class of marine alkaloids isolated from the rare, difficult to access Antarctic sponge Kirkpatricka varialosa, with Variolin B (1) being a typical example.
• the variolins all contain a fused pyrido [3 ',2': 4,5] pyrrolo [1,2-c] pyrimidine core (2), with either a heterocyclic aromatic ring or an ester group attached at C5, as in Variolin B (l) and Variolin D (3).
• the variolins are disclosed to have antitumour activity and other useful properties.
• the complete structure, and antitumour activity, of these and related compounds is described by N.B. Perry et al. Tetrahedron, 1994, 50, 3987-92, and G. Trimurtulu et al, Tetrahedron, 1994, 50, 3993-4000.
• the variolins described in these documents have hitherto only been demonstrated to exhibit a limited range of antitumour activity.
• deoxyvariolin B The route to deoxyvariolin B described in this reference involves a total of at least fourteen steps, in which the fused tricyclic pyridopyrrolopyrimidine core is constructed from a 7-azaindole and a heteroaryl coupling reaction is then used to introduce the fourth aromatic ring to give intermediate (5). Substitution of the derived sulphone group (6) for an amino group gave deoxyvariolin B (4):
• the synthetic methods of the present invention provide the first method for preparation of variolin B (1) and provide short, rapid entry to deoxyvariolin B (4) and intermediates such as (5) and (6). These intermediates have been used in the preparation of new antitumour compounds containing the fused tricyclic pyridopyrrolopyrimidine core of the variolins.
• the invention provides a compound of formula (I):
• R 3 is selected from the group consisting of H, OH and OMe
• R' is independently selected from the group consisting of OH, C1-C 12 alkyl, C ⁇ -C 1 haloalkyl, C 2 -C 12 alkenyl, C 2 -C 12 alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted aralkyl, substituted or unsubstituted arylalkenyl and substituted or unsubstituted heteroaromatic,
• each of the R' groups may be the same or different, or the two R' groups, together with the nitrogen atom to which they are attached, may form a 5-14 membered heterocyclic ring;
• the aryl group and the aryl moiety of the aralkyl and arylalkenyl group is a carbocyclic aryl group having from 6 to 14 carbon atoms in a carbocyclic ring or two or more fused rings;
• the aralkyl group is a CpC 6 alkyl group which is substituted by an aryl group as defined above;
• the arylalkenyl group is a C 2 -C 6 alkenyl group which is substituted by an aryl group as defined above;
• the heteroaromatic group is a heterocyclic aromatic group having from 5 to 14 ring atoms in one ring or two or more fused rings of which at least one ring atom is selected from the group consisting of nitrogen, oxygen and sulphur, and such a heterocyclic aromatic group fused with an aryl group as defined above;
• the substituents on the aryl and heteroaromatic groups and the aryl moiety of the aralkyl and arylalkenyl groups are selected from the group consisting of -C12 alkyl, -C12 haloalkyl, C1-Q 2 alkoxy, -C12 alkylthio, NH2, C C 4 alkylamino, di(C 1 -C 4 alkyl)amino, C ⁇ -C 4 alkanoylamino, di(CpC 4 alkanoyl)amino, NO 2 , CN and halogen;
• Ri is amino, thiomethyl, methylsulfinyl or methylsulfonyl, R 2 is amino and R 3 is hydrogen; or
• Ri and R 2 are amino and R 3 is hydroxy.
• the invention also provides a synthetic process for producing both the new variolin derivatives of formula (I) described above and known variolin derivatives such as those described in the prior art.
• the invention provides a process for producing a compound of formula (I):
• R 3 is selected from the group consisting of H, OH and OMe
• R' is independently selected from the group consisting of OH, C1-C 12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl, C 2 -C 12 alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted aralkyl, substituted or unsubstituted arylalkenyl and substituted or unsubstituted heteroaromatic,
• each of the R' groups may be the same or different, or the two R' groups, together with the nitrogen atom to which they are attached, may form a 5-14 membered heterocyclic ring;
• the aryl group and the aryl moiety of the aralkyl and arylalkenyl group is a carbocyclic aryl group having from 6 to 14 carbon atoms in a carbocyclic ring or two or more fused rings;
• the aralkyl group is a C]-C 6 alkyl group which is substituted by an aryl group as defined above;
• the arylalkenyl group is a C2-C6 alkenyl group which is substituted by an aryl group as defined above;
• the heteroaromatic group is a heterocyclic aromatic group having from 5 to 14 ring atoms in one ring or two or more fused rings of which at least one ring atom is selected from the group consisting of nitrogen, oxygen and sulphur, and such a heterocyclic aromatic group fused with an aryl group as defined above;
• the substituents on the aryl and heteroaromatic groups and the aryl moiety of the aralkyl and arylalkenyl groups are selected from the group consisting of C ⁇ -C 1 alkyl, C ⁇ -C 12 haloalkyl, C ⁇ -Cn alkoxy, C ⁇ -C 12 alkylthio, NH2, C C 4 alkylamino, di(Cj-C 4 alkyl)amino, C ⁇ -C 4 alkanoylamino, di(Cj-C 4 alkanoyl)amino, NO 2 , CN and halogen;
• R la , R2 a and R 3a represent any of the groups represented by R l5 R 2 and R 3 respectively, and all such groups where reactive functional groups are protected; and Y1 and Y2 are groups capable of being eliminated to produce a fused tricyclic pyridopyrrolopyrimidine ring structure.
• the new compounds of formula (I) demonstrate biological activity against mammalian cancer cell lines. Antitumoural activities of these compounds include leukaemias, lung cancer, colon cancer, kidney cancer, prostate cancer, ovarian cancer, breast cancer, sarcomas and melanomas. Further, the known compounds of formula (I) exhibit previously undisclosed activity against a wide range of cancers.
• the invention provides a method for the treatment or prophylaxis of cancer in a mammal, which comprises administering to a mammal in need of such treatment an effective amount of a new compound of the invention.
• the invention provides a method for the treatment or prophylaxis of cancers selected from ovarian cancer, kidney cancer, prostate cancer, breast cancer and melanoma in a mammal, which comprises administering to a mammal in need of such treatment an effective amount of either a new compound of the invention or a variolin compound of the prior art.
• the invention provides synthetic steps to certain preferred compounds, described in more detail later, and to intermediate compounds, especially those of formula (II) above.
• alkyl groups may be straight or branched chain groups and preferably have from 1 to about 12 carbon atoms, more preferably 1 to about 8 carbon atoms, still more preferably 1 to about 6 carbon atoms, and most preferably 1, 2, 3 or 4 carbon atoms.
• Methyl, ethyl and propyl including isopropyl are particularly preferred alkyl groups in the compounds of the present invention.
• the term alkyl unless otherwise modified, refers to both cyclic and noncyclic groups, although cyclic groups will comprise at least three carbon ring members.
• Haloalkyl groups are alkyl groups (including cycloalkyl groups) as defined above which are substituted with one or more halogen atoms (preferably fluorine, chlorine, bromine or iodine) and preferably have from 1 to about 12 carbon atoms, more preferably 1 to about 8 carbon atoms, still more preferably 1 to about 6 carbon atoms, and most preferably 1, 2, 3 or 4 carbon atoms.
• halogen atoms preferably fluorine, chlorine, bromine or iodine
• alkenyl and alkynyl groups in the compounds of the present invention have one or more unsaturated linkages and from 2 to about 12 carbon atoms, more preferably 2 to about 8 carbon atoms, still more preferably 2 to about 6 carbon atoms, even more prefereably 2, 3 or 4 carbon atoms.
• alkenyl and alkynyl as used herein refer to both cyclic and noncyclic groups, although straight or branched noncyclic groups are generally more preferred.
• Preferred alkoxy groups in the compounds of the present invention include groups having one or more (but preferably only one) oxygen linkages and from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms, and most preferably 1, 2, 3 or 4 carbon atoms.
• Preferred alkylthio groups in the compounds of the present invention have one or more (but preferably only one) thioether linkages and from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.
• Alkylthio groups having 1, 2, 3 or 4 carbon atoms are particularly preferred.
• Preferred alkylsulfmyl groups in the compounds of the present invention include those groups having one or more sulfoxide (SO) groups and from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.
• Alkylsulfmyl groups having 1, 2, 3 or 4 carbon atoms are particularly preferred.
• Preferred alkylsulfonyl groups in the compounds of the present invention include those groups having one or more sulfonyl (SO 2 ) groups and from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms. Alkylsulfonyl groups having 1, 2, 3 or 4 carbon atoms are particularly preferred.
• Preferred alkanoyl groups in the compounds of the present invention include those groups having one or more carbonyl (CO) groups and from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms (including the carbonyl carbon).
• Preferred alkylamino groups in the compounds of the present invention have one or more (but preferably only one) NH linkages and from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.
• Preferred dialkylamino groups in the compounds of the present invention have one or more (but preferably only one) nitrogen atom bonded to two alkyl groups, each of which may from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.
• the alkyl groups may be the same or different.
• Preferred alkanoylamino groups in the compounds of the present invention have one NH-CO- linkage bonded to an alkyl group having from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.
• the acetylamino group is especially preferred.
• Preferred dialkanoylamino groups in the compounds of the present invention have one ' nitrogen atom bonded to two alkanoyl groups as defined above, each of which may be the same or different and has from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.
• the diacetylamino group is especially preferred.
• Preferred alkylsulfonylamino groups in the compounds of the present invention have one NH-SO2- linkage bonded to an alkyl group having from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.
• each group R' being independently selected from the group consisting of OH, d- C ⁇ alkyl, C1-Q2 haloalkyl, aryl (which may optionally be substituted with a group selected from d-C 6 alkyl, d-C 6 alkoxy, C ⁇ -C 6 alkylthio, NH 2 , d-C 6 alkylamino, di(C C6 alkyl)amino, NO2, CN and halogen), aralkyl or arylalkenyl (the aryl moiety of which may optionally be substituted with a group selected from Cj-C 6 alkyl, C1-C 6 alkoxy, C ⁇ -C 6 alkylthio, NH 2 , d-C 6 alkylamino, di(C ⁇ -C 6 alkyl)amino, NO 2 , CN and halogen), and wherein the group Rj is a group of formula N(R') 2 or N(COR') 2
• Ri is selected from the group consisting of OR', SR', SOR', NH 2 , NHR', N(R') 2 , NHCOR', N(COR') 2 and NHSO 2 R', the or each group R' being independently selected from the group consisting of Cj-C 6 alkyl, Cj-C 6 haloalkyl, aryl (which may optionally be substituted with a group selected from Ci-C ⁇ alkyl, d-C 6 alkoxy and halogen), aralkyl (the aryl moiety of which may optionally be substituted with a group selected from C ⁇ -C 6 alkyl, Cj-C 6 alkoxy and halogen), aralkenyl (the aryl moiety of which may optionally be substituted with a group selected from C ⁇ -C 6 alkyl, Cj-C alkoxy and halogen), and wherein the group is a group of formula N(R') 2 or N(COR') 2
• Rj is selected from the group consisting of d-C 4 alkoxy, C 1 -C 4 alkylthio, C1-C 4 alkylsulfmyl, amino, C1-C4 alkylamino, di(Cj-C 4 alkyl)amino, Cj-C 4 alkanoylamino, di(d-C 4 alkanoyl)amino, C1-C4 haloalkanoylamino, arylamino (wherein the aryl moiety may optionally be substituted with a C 1 -C 4 alkoxy group), benzylamino (wherein the phenyl part of the benzyl moiety may optionally be substituted with a C1-C4 alkoxy group), cinnamoylamino or dicinnamoylamino (wherein the phenyl part of the or each cinammoyl moiety may optionally be substituted with a C1-C4 alk
• Ri is selected from methoxy, thiomethyl, methylsulfinyl, amino, methylamino, ethylamino, benzylamino, acetylamino, trifluoroacetylamino, diacetylamino, cinnamoylamino, dicinnamoylamino, p-methoxybenzylamino and piperidino.
• R] is selected from amino, benzylamino, acetylamino, trifluoroacetylamino, diacetylamino, cinnamoylamino, dicinnamoylamino and p- methoxybenzylamino .
• R 2 is selected from the group consisting of OR', SR', SOR', NH 2 , NHR', N(R') 2 , NHCOR', N(COR') 2 and NHSO 2 R', the or each group R' being independently selected from the group consisting of Cj-C 6 alkyl, C ⁇ -C 6 haloalkyl, aryl (which may optionally be substituted with a group selected from C ⁇ -C 6 alkyl, C ⁇ -C 6 alkoxy and halogen), aralkyl (the aryl moiety of which may optionally be substituted with a group selected from d-C 6 alkyl, C ⁇ -C 6 alkoxy and halogen), aralkenyl (the aryl moiety of which may optionally be substituted with a group selected from d-C 6 alkyl, C ⁇ -C 6 alkoxy and halogen), and wherein the group R 2 is a group of formula N(R') 2 or N(
• R 2 is selected from the group consisting of d-C 4 alkoxy, d-C 4 alkylthio, C1-C 4 alkylsulfmyl, amino, C1-C 4 alkylamino, di(C ⁇ -C 4 alkyl)amino, C1-C 4 alkanoylamino, di(d-C4 alkanoyl)amino, C1-C4 haloalkanoylamino, arylamino (wherein the aryl moiety may optionally be substituted with a C 1 -C 4 alkoxy group), benzylamino (wherein the phenyl part of the benzyl moiety may optionally be substituted with a C 1 -C 4 alkoxy group), cinnamoylamino or dicinnamoylamino (wherein the phenyl part of the or each cinammoyl moiety may optionally be substituted with a C1-C 4 alk
• R 2 is selected from thiomethyl, methylsulfinyl, amino, methylamino, ethylamino, acetylamino, diacetylamino, cinnamoylamino, and p- methoxybenzylamino. Most preferably, R 2 is selected from amino, acetylamino, diacetylamino and p-methoxybenzylamino.
• R 3 is H.
• Ri, R 2 and R 3 above may be combined in various ways, and the compounds covered by such combinations of the above preferred definitions are to be considered as being part of this invention. A combination of two of these definitions is preferred, and a combination of all three preferred definitions is especially preferred.
• the compounds of formula (I) contain a basic group, and may therefore form a salt.
• the nature of such salts is not critical to the present invention, provided that, when the compound is used for therapeutic purposes, the salts are pharmaceutically acceptable, ie more biologically active, about as biologically active or not unduly less biologically active than the free base compound, and less toxic, about as toxic or not unduly more toxic than the free base compound. This can easily be ascertained by simple tests readily apparent to those skilled in the art. However, when the compound is used for other purposes (for example, as an intermediate in the preparation of another compound) even this restriction does not apply.
• suitable salts include inorganic acid salts such as hydrochloride, hydrobromide, sulfate and phosphate; organic acid salts such as acetate, benzoate, oxalate, maleate, fumarate, tartrate, citrate and succinate; and sulfonic acid salts such as methanesulfonate, benzenesulfonate and p-toluenesulfonate.
• Preferred salts include hydrochloride, hydrobromide, tartrate and succinate.
• esters may therefore form an ester.
• the nature of such esters is not critical to the present invention, provided that, when the compound is used for therapeutic purposes, the esters are pharmaceutically acceptable, ie more biologically active, about as biologically active or not unduly less biologically active than the free acid compound, and less toxic, about as toxic or not unduly more toxic than the free acid compound.
• the ester group is physiologically removable, ie the ester can be readily converted in vivo to the free acid. This can easily be ascertained by simple tests readily apparent to those skilled in the art.
• the compounds of the present invention contain at least four tertiary amine groups, of which one or more (but preferably only one) may be quaternised to form a quaternary ammonium salt.
• a counter ion is also present; examples of suitable counter ions are defined above with reference to salts.
• the procedure for quaternising the nitrogen atom(s) is readily apparent to those skilled in the art. It is preferred that the group attached to the tertiary amino group to form a quaternary ammonium species is a C ⁇ -C 6 alkyl group, most preferably a methyl group.
• variolin derivatives of formula (I), including the known variolin compounds, are produced by a novel process which forms part of the present invention.
• R la , R 2a and R 3a represent any of the groups represented by R l5 R2 and R 3 respectively, and all such groups where reactive functional groups are protected; and Yi and Y2 are groups capable of being eliminated to produce a fused tricyclic pyridopyrrolopyrimidine ring structure.
• the intermediates of formula (II) are novel compounds and also form part of the present invention.
• any groups capable of being eliminated to produce a fused tricyclic pyridopyrrolopyrimidine ring structure may be used as the groups Yi and Y2.
• the group Yj is a hydroxy group or a labile ester group such as acetate, methanesulfonate, p- toluenesulfonate or trifluoromethanesulfonate, more preferably a hydroxy group.
• the group Y 2 is a halogen atom, more preferably a chlorine atom.
• the intermediate of formula (II) is symmetrical, ie R la and R 2a are the same: as described below, this allows the intermediate to be made by addition of two equivalents of reagent to a precursor; this in turn shortens the synthesis. More preferably, R la and R 2a are both methylthio groups.
• the intermediate of formula (II) can be made by a number of methods.
• One preferred method is by reacting an intermediate compound of formula (IV):
• the nature of the metal atom M is not particularly critical, provided that the compound is sufficiently reactive to undergo addition to the compound of formula (V).
• suitable metallated species include those where M is Li, Na, K, Mg or Zn; in the case of metallated species with divalent metal ions, a further counterion such as halogen may also be present, or the compound may be in the form of a diorganometallic species.
• M is Li.
• the compound of formula (IV) is typically produced in situ by metallating the corresponding halo compound.
• Suitable reagents are well known in the art, and examples include the metal itself or another more active metallating compound such as an alkylmetal derivative. Alkyllithium derivatives are preferred and butyllithium is especially preferred.
• the compound of formula (V) is preferably produced by reacting an intermediate compound of formula (VI):
• the nature of the metal atom M is not particularly critical, provided that the compound is sufficiently reactive to undergo addition to the compound of formula L 1 -CO-L 2 .
• suitable metallated species include those defined and exemplified above in relation to the compound of formula (IV). We prefer that M is Li.
• the compound of formula (VI) is typically produced in situ by metallating the corresponding halo compound, ie a compound of formula (VIII):
• R la is as defined above and X is a halogen atom, preferably bromine or iodine.
• Suitable reagents and procedures for metallating the compound of formula (VIII) to produce the compound of formula (VI) are known in the art. Examples include the metal itself or another more active metallating compound such as an alkylmetal derivative. Alkyllithium derivatives are preferred and butyllithium is especially preferred.
• Li and L2 may be the same or different and each represents a leaving group, the precise nature of which is not especially critical. Non- limiting examples of suitable leaving groups include halogen, C ⁇ -C 6 alkoxy, di(Cj-C 6 alkyl)amino, nitrogen-containing heterocyclic (especially imidazole) or a labile ester group such as those defined above in relation to Yi. Diethyl carbonate is a particularly preferred example of a compound of formula L1-CO-L 2 .
• the compound of formula (II) is produced by reacting an intermediate compound of formula (VI), described above, with an intermediate compound of formula (VII):
• the group Z is a leaving group, examples of which are defined above with reference to Y ⁇ , L[ and L 2 . It is particularly preferred that Z is a halogen atom, especially chlorine, as two equivalents of the metallated compound of formula (VI) can add cleanly to the compound of formula (VII).
• the elimination of the groups Yi and Y 2 is preferably carried out by reacting the intermediate of formula (II) with a trialkylsilane of formula R a R D R c SiH wherein R a , R b and R e may be the same or different and each represents a C ⁇ -C 12 alkyl group.
• a trialkylsilane of formula R a R D R c SiH wherein R a , R b and R e may be the same or different and each represents a C ⁇ -C 12 alkyl group.
• triethylsilane is used as the reagent.
• reaction is preferably carried out in the presence of acid, the precise nature of which is not particularly critical.
• a strong organic acid such as p-toluenesulfonic acid or trifluoroacetic acid is preferred and trifluoroacetic acid is especially preferred.
• the intermediate compound of formula (III) may then be converted to a compound of formula (I) by functional group interconversions, the general nature of which is known to those skilled in the art.
• the amine groups of the known compound deoxyvariolin B (4), prepared by the process of the present invention may readily be converted into a variety of functionalised derivatives as shown in Scheme I and exemplified below.
• a further group of analogs may be generated by functionalisation of the C5 heteroaromatic ring of the variolins. This can be readily achieved from intermediate (5) by oxidation to the sulphone (6) or sulphoxide (22) followed by nucleophilic substitution reactions, as shown in Scheme II.
• the invention provides a process for producing a compound of formula (I) wherein Ri and R 2 are amino groups and R 3 is as defined above, said process comprising:
• the protecting group is a substituted or unsubstituted benzyl group or a phthalimide group, especially a p-methoxybenzyl (PMB) group.
• the group may be removed by any conventional route, such as under acid conditions (especially a strong organic acid, for example trifluoromethanesulfonic acid or trifluoroacetic acid), under oxidising conditions, for example dichlorodicyanobenzoquinone (DDQ) or reductive conditions, for example with hydrogen and a palladium catalyst.
• acid conditions especially a strong organic acid, for example trifluoromethanesulfonic acid or trifluoroacetic acid
• oxidising conditions for example dichlorodicyanobenzoquinone (DDQ) or reductive conditions, for example with hydrogen and a palladium catalyst.
• DDQ dichlorodicyanobenzoquinone
• reductive conditions for example with hydrogen and a palladium catalyst.
• the invention provides a process for producing a compound of formula (I) wherein R is a methylthio or amino group, R 2 is an amino group and R 3 is as defined in claim 1 , from a compound of formula (III), wherein R la and R 2a are methylthio and R 3a is as defined in claim 19, said process comprising: a) optionally, oxidising the compound of formula (III) wherein R la and R 2a are methylthio to a compound of formula (III) wherein R la andJ .
• oxidising agent capable of oxidising thioethers to sulfoxides may be used to achieve the optional oxidation step a) of the above process.
• suitable oxidising agents include hydrogen peroxide, sodium periodate, t-BuOCl, sodium perborate, and peracids such as peracetic acid, m-chloroperbenzoic acid (mCPBA) or magnesium monoperoxyphthalate (MMPP), of which peracids are preferred and mCPBA is especially preferred.
• the novel methodology employed to construct the core variolin skeleton allows the synthesis of deoxyvariolin B (4) to be completed in a total of only five steps from the simple monoheteroaromatic starting material (7). This synthesis is significantly shorter than the sequence to deoxyvariolin B described in the prior art.
• the novel synthetic approach of the present invention allows construction of the core variolin skeleton, consisting of the fused pyridopyrrolopyrimidine core bearing a heterocyclic aromatic ring at C5, as in (13), in only four steps from the simple monoheteroaromatic starting material (7).
• this invention provides new compounds that can be made from intermediates prepared by a new process that is part of this invention.
• the synthetic routes of the invention each comprise a number of transformation steps to arrive at the desired product.
• Each step in itself is a process in accordance with this invention.
• the invention is not limited to the routes that are exemplified, and alternative routes may be provided by, for example, changing the order of the transformation steps, as appropriate.
• variolin B in more detail, the synthesis of variolin B according to an especially preferred embodiment of the current invention involves the following eight steps.
• starting material (7) is transformed into deoxyvariolin B involving the following five further steps.
• compositions include any solid (tablets, pills, capsules, granules, etc.) or liquid (solutions, suspensions or emulsions) with suitable composition or oral, topical or parenteral administration, and they may contain the pure compound or in combination with any carrier or other pharmacologically active compounds. These compositions may need to be sterile when administered parenterally.
• the correct dosage of the compounds will vary according to the particular formulation, the mode of application, and the particular situs, host and tumour being treated. Other factors like age, body weight, sex, diet, time of administration, rate of excretion, condition of the host, drug combinations, reaction sensitivities and severity of the disease shall be taken into account. Administration can be carried out continuously or periodically within the maximum tolerated dose.
• Administration of the compounds or compositions of the present invention may be by any suitable method, such as intravenous infusion, oral preparations, intraperitoneal and intravenous administration.
• a colorimetric type of assay, using sulforhodamine B (SRB) reaction has been adapted for a quantitative measurement of cell growth and viability: see Skehan, P.A. et al. J. Natl. Cancer Inst, 1990, 82, 1107-1112.
• This form of the assay employs 96 well cell culture microplates of 9 mm diameter (Faircloth, G.T.; Stewart, D. and Clement, J.J., Journal of Tissue and Culture Methods, 1983, 11, 201-205; Mosmann, T. Journal of Immunological Methods, 1983, 65, 55-63.). Most of the cell lines are obtained from American Type Culture Collection (ATCC) derived from different human cancer types.
• ATCC American Type Culture Collection
• Cells are maintained in RPMI 1640 10% FBS, supplemented with 0.1 g/1 penicillin and 0.1 g/1 streptomycin sulfate and then incubated at 37°C, 5% CO2 and 98% humidity. For the experiments, cells were harvested from subconfluent cultures using trypsin and resuspended in fresh medium before plating.
• Cells are seeded in 96 well microtiter plates, at 5 x 103 cells per well in aliquots of 195 ⁇ l medium, and they are allowed to attach to the plate surface by growing in drug free medium for 18 hours. Afterward, samples are in aliquots of 5 ⁇ l in a ranging from 10 to 10-8 ⁇ g/ml dissolved in DMSO/EtOH (0.2% in PS buffer). After 48 hours exposure, the antitumour effect are measured by the SRB methodology: cells are fixed by adding 50 ⁇ l of cold 50% (w/v) trichloroacetic acid (TCA) and incubating for 60 minutes at 4°C. Plates are washed with deionized water and dried.
• TCA trichloroacetic acid
• GI growth inhibition
• TGI total growth inhibition (cytostatic effect)
• LC cell killing (cytotoxic effect).
• Tumor Type I NSCLColon Melanoma
• COMPOUND Cell line A-549 HT-29 SW-620 MEL-28
• Tumor Type Ovary Kidney Prostate Breast
• COMPOUND Cell line OVCAR-3 A498 DU-I45 MCF-7 MB-231
• Processes for producing the compounds and intermediates of the present invention are described in the Examples below. In the Process Examples are described processes according to the present invention for producing known compounds. The production of intermediate compounds not part of the present invention is described in the Reference Examples.
• Bis-sulfide 13 (37 mg, 0.10 mmol) was dissolved in CHC1 3 (5 mL) under atmospheric conditions and cooled in a -40°C bath. A pre-cooled (-40°C) solution of m- chloroperbenzoic acid in CHC1 3 (10 mg/mL) was added dropwise to the solution until TLC analysis indicated the complete consumption of starting material (approx. 2 equiv of m-CPBA was used). The solution was warmed to room temperature and neutralised with saturated NaHCO 3 solution. This was repeatedly extracted with CH 2 CI 2 and after the standard work-up, a yellow solid was obtained, which was predominantly a mixture of diastereomeric bis-sulfoxides. The crude mixture was used without purification, however the bis-sulfoxides 14 had the following spectroscopic characteristics:
• the crude oxidised material was heated with an excess of/?-methoxybenzylamine (0.15 mL, 1.1 mmol) at 85 °C for 15 h.
• the crude red paste was purified by flash chromatography on silica gel using gradient elution (2.5-4% MeOH/CH 2 Cl 2 ).
• the yellow fractions were re-chromatographed using gradient elution (50% EtOAc/CH 2 Cl 2 to 100% EtOAc) to give bis-amine 15 as a yellow solid (43 mg, 78% over two steps).
• the red residue was purified by flash chromatography using ethyl acetate:hexane 1 :4 to ethyl acetate :hexane 1 :3 as eluent to afford the pyridopyrrolopyrimidine 19 (0.3 g, 33%) as a pale yellow solid.
• Butylmethylamine (0.029 ml, 0.24 mmol) was added to a solution of sulfinyldeoxyvariolin 22 (prepared as described in Process Example 5 below) (8 mg, 2.4x10 "5 mol) in THF (2 ml). The yellow solution was stirred at 70°C overnight and evaporated at reduced pressure. The yellow residue was purified by flash chromatography using DCM/MeOH (2%) to DCM/MeOH (4%) as eluent to afford N'- butylmethyldeoxyvariolin 28c (2 mg, 62 % based on recovered starting material) as a yellow oil.
• Benzylamine (0.050 ml, 0.45 mmol) was added to a solution of sulfinyldeoxyvariolin 22 (4 mg, 1.2xl0 "5 mol) in THF (1.5 ml). The yellow solution was stirred at 70°C overnight and evaporated at reduced pressure. The yellow residue was purified by flash chromatography using DCM/MeOH (2%) to DCM/MeOH (4%) as eluent to afford N'- benzyldeoxyvariolin 28d (2.1 mg, 47 %) as a yellow oil.
• Trifluoroacetic anhydride (6 ⁇ l, 4.3x10 "" mol) was added to a solution of deoxyvariolin 4 (4 mg, 1.4xl0 "5 mol) in THF (1.5 ml). The yellow solution was stirred at 24°C overnight and evaporated at reduced pressure. The yellow residue was dissolved in DCM (5 ml) and washed with a saturated solution of NaHCO 3 (4 ml). The organic layer was dried, filtered and evaporated under reduced pressure.
• Cinnamoyl chloride (9 ⁇ l, 5.4x10 "5 mol) was added to a solution of deoxyvariolin 4 (5 mg, 1.8xl0 "5 mol) (prepared as described in Process Example 2 or 4 below) and Et 3 N (12 ⁇ l, 5.4xl0 "5 mol) in THF (2 ml).
• DMAP (1 mg, 0.9xl0 "5 mol) was added in one portion, the yellow solution was stirred at 24°C overnight and evaporated at reduced pressure.
• the yellow residue was dissolved in DCM (5 ml) and washed with a saturated solution of NaHCO 3 (4 ml). The organic layer was dried, filtered and evaporated under reduced pressure.
• N'- biscinnamoyldeoxyvariolin 24a 1.1 mg, 21% based on recovered starting material
• N'-biscinnamoyl-N-cinnamoyldeoxyvariolin 24b 0.6 mg, 9 % based on recovered starting material
• Example 14 Compounds 23a, 23b and 23c
• Acetyl chloride (3.5 ⁇ l, 4.8xl0 "5 mol) was added to a solution of deoxyvariolin 4 (9 mg, 3.2xl0 "5 mol) (prepared as described in Process Example 2 or 4 below) and Et 3 N (9 ⁇ l, 6.5x10 "5 mol) in THF (2 ml). The orange slurry was stirred at 24°C overnight and evaporated at reduced pressure. The yellow residue was dissolved in DCM (5 ml) and washed with a saturated solution of NaHCO 3 (4 ml). The organic layer was dried, filtered and evaporated under reduced pressure.
• N'-bisacetyldeoxyvariolin 23a (1 mg, 26 % based on recovered starting material
• N'- bisacetyl-N-acetyldeoxyvariolin 23b (1 mg, 23 % based on recovered starting material
• N'-bisacetyl-N-bisacetyldeoxyvariolin 23c 0.5 mg, 10 % based on recovered starting material
• Acetyl chloride (1.5 ⁇ l, 1.8xl0 "5 mol) was added to a solution of deoxyvariolin 4 (prepared as described in Process Example 2 or 4 below) (5 mg, 1.8xl0 "5 mol) and Et 3 N (4 ⁇ l, 2.7xl0 "5 mol) in THF (1.5 ml) at -78°C. The orange slurry was stirred overnight increasing the temperature very slowly until room temperature and afterwards evaporated at reduced pressure. The yellow residue was dissolved in DCM (5 ml) and washed with a saturated solution of NaHCO 3 (4 ml). The organic layer was dried, filtered and evaporated under reduced pressure.
• deoxyvariolin 4 prepared as described in Process Example 2 or 4 below
• the reaction mixture was re-cooled to below -90 °C and a solution of ketone (9) (1.14 g, 4.09 mmol) in THF (10 mL) was added over 11 min, keeping the temperature below -90 °C.
• the dark mixture was stirred at -78 °C for 3.5 h, then quenched with methanol and allowed to warm to room temperature.
• the reaction mixture was shaken with aqueous NFLjCl solution, extracted with ethyl acetate (x 3) and subjected to standard workup.
• Alcohol 16 (prepared as described in Example 3 above) (33 mg, 0.062 mmol) was dissolved in neat triflic acid (0.4 mL) under atmospheric conditions. The flask was sealed and the deep red solution was left at room temperature for 5 h. The flask was cooled in ice and MeOH (2 mL) was added dropwise. Addition of concentrated aqueous ammonia (2 mL) produced a bright yellow precipitate. The suspension was applied to the top of a chromatography column containing reverse-phase silica, which had been equilibrated with 50% MeOH/water. The yellow suspension was applied to the column with 20% MeOH/water (50 mL).
• the polarity of the eluting solvent system was decreased to 80% MeOH/water (50 mL), and then to 85% MeOH/water containing 0.1% TFA, whereupon the yellow product began to elute.
• the bright yellow fractions were combined and concentrated in vacuo to give variolin B as its trifluoroacetate salt.
• MeOH (10 mL) was added, followed by concentrated aqueous ammonia (1-2 mL) to give the free base. Removal of the solvents under reduced pressure, followed by drying (35 °C, 0.03 mm Hg) overnight gave variolin B (1) (10 mg, 55%), which was identical in all aspects with the natural material.
• N', N-bis(p-methoxybenzyl)deoxyvariolin 29 (Example 5) (15 mg, 2.9xl0 "5 mol) was treated with neat triflic acid (1.5 ml) and stirred for 17 h at 24°C. The black solution was evaporated at reduced pressure and the black slurry was dissolved in DCM (4 ml) and washed with a saturated solution of NaHCO 3 (5 ml). The aqueous layer was extracted with DCM (3 x 5 ml) and the combined organic layers were dried, filtered and evaporated.
• Iodopyrimidine 8 was prepared following the experimental procedure described in the literature: Majeed, A.J.; Antonsen. O.; Benneche, T.; Undheim, K. Tetrahedron 1989, 45, 993.
• Reference Example 2 Compound 9

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