Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07H—SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS
  • C07H19/00—Compounds containing a hetero ring sharing one ring hetero atom with a saccharide radical; Nucleosides; Mononucleotides; Anhydro-derivatives thereof
  • C07H19/02—Compounds containing a hetero ring sharing one ring hetero atom with a saccharide radical; Nucleosides; Mononucleotides; Anhydro-derivatives thereof sharing nitrogen
  • C07H19/04—Heterocyclic radicals containing only nitrogen atoms as ring hetero atom
  • C07H19/16—Purine radicals
  • C07H19/20—Purine radicals with the saccharide radical esterified by phosphoric or polyphosphoric acids
  • C07H19/213—Purine radicals with the saccharide radical esterified by phosphoric or polyphosphoric acids containing cyclic phosphate
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07H—SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS
  • C07H1/00—Processes for the preparation of sugar derivatives
  • C07H1/02—Phosphorylation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07H—SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS
  • C07H19/00—Compounds containing a hetero ring sharing one ring hetero atom with a saccharide radical; Nucleosides; Mononucleotides; Anhydro-derivatives thereof
  • C07H19/02—Compounds containing a hetero ring sharing one ring hetero atom with a saccharide radical; Nucleosides; Mononucleotides; Anhydro-derivatives thereof sharing nitrogen
  • C07H19/04—Heterocyclic radicals containing only nitrogen atoms as ring hetero atom
  • C07H19/23—Heterocyclic radicals containing two or more heterocyclic rings condensed among themselves or condensed with a common carbocyclic ring system, not provided for in groups C07H19/14 - C07H19/22
• • 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
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/55—Design of synthesis routes, e.g. reducing the use of auxiliary or protecting groups

Definitions

• the present invention relates to a method for preparing cyclic guanosine-3', 5'- monophosphate analogues.
• the invention also relates to the new cyclic guanosine-monophosphate analogues and intermediates obtained by the method.
• Retinitis pigmentosa is a group of severely disabling inherited neurodegenerative diseases.
• rod photoreceptor cells permitting vision under dim light conditions - degenerate first during the course of the disease. Subsequently, the loss of rods triggers a secondary degeneration of cone photoreceptor cells, the source of high-resolution colour vision in daylight, eventually leading to complete blindness.
• retinitis pigmentosa Genes mutated in retinitis pigmentosa are usually associated with photoreceptor function, but there are also such that relate to general cellular functions (Kennan et al. 2005, Trends Genet. 21 , 103-110).
• the molecule cGMP cyclic guanosine-monophosphate
• retinitis pigmentosa mutations lead to an excessive accumulation of cGMP in photoreceptors (Arango-Gonzalez et al. 2014 PLoS One.
• the increased cGMP can be envisaged to have at least one of four targets: 1) cGMP dependent protein kinase (protein kinase G; PKG), which when activated by cGMP, will phosphorylate specific proteins, 2) cyclic nucleotide gated ion channels (CNGC), which, when activated by cGMP, allow for a cGMP controlled influx of Na + and Ca 2+ , 3) phosphodiesterase (PDE), and 4) hyperpolarization-activated cyclic nucleotide-gated (HCN) channel.
• cGMP dependent protein kinase protein kinase G
• CNGC cyclic nucleotide gated ion channels
• PDE phosphodiesterase
• the first two cGMP targets are directly connected with photoreceptor degeneration (Paquet-Durand et al. 2009, J. Neurochem. 108, 796-810; Paquet-Durand et al. 2011 , Hum. Mol. Genet. 20, 941-947), while the others are known cGMP targets and hence potentially involved in the degenerative process. Due to their direct connection with the early events, PKG and CNGC can be regarded as disease drivers, even though the downstream mechanisms are still not understood in great detail (Trifunovic et al. 2012, Curr. Mol. Med. 12, 598-612).
• cGMP-derived PKG inhibitors also known as cGMP analogues (such as e.g.
• Rp-8-Br- cGMPS are known to offer protection of rd1 and rd2 photoreceptors both in vitro and in in vivo mouse retinitis pigmentosa models (Paquet-Durand et al., 2009).
• cGMP analogues are known in the art.
• WO2012130829 describes boranophosphate analogues of cyclic nucleotides.
• WO2018/010965 describes multimeric complexes of cGMP analogues. Butt et al.
• (Rp)-cGMPS and (Rp)-8-CI-cGMPS antagonized the activation of the cGMP-dependent protein kinase.
• (Rp)-cGMPS also antagonized the activation of cAMP-dependent protein kinase.
• (Rp)-8-CI-cGMPS was a weak inhibitor of the cAMP-dependent protein kinase.
• (Rp)-8-CI-cGMPS appears to be a rather selective inhibitor of the cGMP-dependent protein kinase.
• cGMP analogues Synthesis of cGMP analogues is known in the art, but known protocols are only viable at laboratory scale, such as those described in Sekhar et al. (1992, Mol. Pharmacol., 42: 103 - 108) and Miller et al. (1973, Biochemistry 12: 5310 - 5319). This is because synthesis often involves laborious purification steps involving chromatography. Extensive chromatography may be required to separate different stereoisomers of the cGMP analogues, which may be in either an Sp or Rp configuration, where the Rp stereoisomer is the more potent substance.
• cGMP analogues for example as described for a cAMP analogue in scheme 4 on page 18 of WO 2005/123755, involves introduction of phosphorus, followed by cyclisation. As described therein, the initial phosphorylation is thought to takes place at the 5'-OH group in the sugar, while the 2’-OH and 3’-OH group were also unprotected. This intermediate is never isolated. Instead, the products are then cyclised directly at high dilution by alkali hydroxide in aqueous acetonitrile to give the diastereoisomeric nucleosides-3',5'-cyclic phosphorothioates cAMP in roughly a 1 :1 ratio which have to be separated by chromatographic techniques.
• h is H or halogen or Q, preferably H or Br or Q, more preferably Br;
• X 1 is H and X 2 is p';
• the phosphorous oxoacid derivative of step ii) is a phosphorylating agent or a phosphonylating agent, preferably the phosphorous oxoacid derivative of step ii) is of general formula (P): wherein M is S or O or is absent; o 1 and o 2 are each independently selected from halogen, -O-Ci-shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, borano, methylborano, dimethylborano, cyanoborano, and -N(Ci-shydrocarbon)2; and o 3 is H or is as defined for o 1 ; or o 1 and o 3 together form a chiral auxiliary that is preferably a C2-i2hydrocarbon.
• P general formula
• the guanosine 5’-monophosphorous oxoacid ester analogue obtained in step ii) is of general formula (II) or a salt thereof: wherein o 1 and o 3 are each independently -OH or as defined above; and wherein M is S or O.
• the guanosine analogue of general formula (I) or salt thereof is provided by the steps of: la) providing an unprotected guanosine analogue of general formula (pl) or a salt thereof: lb) contacting the unprotected guanosine analogue with (tri)alkylsilylhalide to obtain a multiply protected guanosine analogue and optionally isolating the multiply protected guanosine analogue by crystallization; and lc) selectively deprotecting the multiply protected guanosine analogue to obtain the guanosine analogue of general formula (I) wherein X 1 is H and X 2 is p'; and ld) optionally isolating the obtained guanosine analogue of general formula (I) wherein X 1 is H and X 2 is p' by crystallization.
• the method further comprises a step: iv) cyclizing the guanosine 5’-monophosphorous oxoacid ester analogue obtained in step ii) to obtain a cyclic guanosine-3', 5'-monophosphate (cGMP) analogue, wherein said cyclisation is preferably performed in the presence of a sterically hindered base.
• cGMP cyclic guanosine-3', 5'-monophosphate
• the cGMP analogue is of general formula (III) or a salt thereof: wherein preferably X 2 is p' as defined above; and preferably o 3 is H; and the method optionally further comprises a step: v) contacting the cGMP analogue with a sulfurizing agent to obtain a thiolated cGMP analogue of general formula (III) wherein o 3 is -SH or-S-Ci-i2hydrocarbon, preferably -SH.
• the cGMP analogue of general formula (III) is of general formula (lll-Rp): wherein preferably X 2 is p' and preferably o 3 is H, optionally wherein the thiolated cGMP analogue is of general formula (lll-Rp), preferably X 2 is p'; wherein o 3 is -SH or -S-Ci- i2hydrocarbon, preferably -SH.
• X 2 is p', and the method further comprises the steps of: vi) deprotecting the hydroxyl moiety that is protected by X 2 to obtain a deprotected cGMP analogue; and vii) optionally triturating the deprotected cGMP analogue; and viii) optionally converting the deprotected cGMP analogue to a pharmaceutically acceptable salt, preferably a sodium salt.
• a compound of general formula (II) or a salt thereof wherein h, X 1 , X 2 , R 1 , and R 2 are as defined above; wherein o 1 and o 3 are each independently -OH or as defined above, wherein preferably o 3 is H or o 1 and o 3 together form a chiral auxiliary that is preferably a C2-i2hydrocarbon; wherein M is S or O; wherein preferably the compound is a salt.
• the compound is crystalline.
• o 3 is H.
• h is Br
• X 1 is H and X 2 is p'
• p' is preferably triisopropylsilyl (TIPS)
• ar is phenyl
• o 1 is OH
• o 3 is H
• M is S or O, preferably O.
• the present invention provides an improved method for synthesis of cGMP analogues.
• the inventors surprisingly found that a key intermediate, the guanosine 5’-monophosphorous oxoacid ester analogue formed after phosphorous is first introduced, which can also be referred to as the H-phosphonate monoester, could be crystallized.
• isolation of this intermediate allowed subsequent steps to yield products having such a degree of purity that chromatographic separation is not required for cGMP synthesis using the method of this invention.
• guanosine 5’-monophosphorous oxoacid ester analogue intermediate allowed more precise control over reaction conditions for subsequent cyclisation, allowing improved yield of Rp-analogues, even up to yielding Rp-analogues without requiring chromatography at any point.
• the method allowed synthesis at scales of as little as 50 mg to well over 100 gram. The method can be easily scaled owing to its homogeneous reaction steps, reactivity at room temperature, and lack of exotherms.
• the invention provides a method for producing a cyclic guanosine-3', 5'-monophosphate (cGMP) analogue or a synthetic intermediate thereof, the method comprising the steps of: i) providing a guanosine analogue of general formula (I) or a salt thereof: wherein: h is H, halogen, or Q;
• X 1 and X 2 are each independently chosen from H or p'; p' is in each instance independently chosen from a hydroxyl protective group;
• Q is -(CH 2 )n-S-(CH 2 )n-H, -S-(CH 2 )n-OH, -S-(CH 2 )n-NH 2 , -(CH 2 )n-O-(CH 2 )n-H, -O-(CH 2 )n-OH, -O-(CH 2 )n-NH 2 , -O-C(CH 3 )3, -O-CH(CH 3 )2, -(CH 2 )n-N(-[CH 2 ]nH)2, -NH-(CH 2 )nNH 2 , -NH-(CH 2 )n OH, - (CH 2 )n-Nc 1 c 2 wherein c 1 and c 2 together with the N to which they are attached form a 3 to 8 membered heterocycle or wherein c 1 is H and c 2 is a 3 to 8 membered heterocycle, -(CH2)n-H, -N3, -CF 3
• Such a method is referred to hereinafter as the method according to the invention.
• the method is for the production of cGMP analogues, but is also highly suitable for producing intermediates useful in the further production of cGMP analogues.
• the method is for producing cGMP analogues.
• the method is for producing intermediates suitable for further conversion towards cGMP analogues.
• Preferred synthetic intermediates produced by the method according to the invention are compounds of general formula II, compounds of general formula III, compounds of general formula lll-Rp, or salts thereof. Definitions for salts and for these compounds are provided later herein.
• the intermediate is of general formula II or lll-Rp.
• the intermediate is of general formula III.
• the intermediate is of general formula lll-Rp.
• Compounds of general formula II are most preferred intermediates.
• cGMP analogues produced by the method are described below. In general, they are governed by the target binding proteins that are to be modulated by application of the cGMP analogue.
• the cGMP analogue is for activation of a cyclic guanosine- 3’, 5’- monophosphate dependent protein kinase
• the preferred cGMP analogue is of general formula III wherein o 3 is OH or is of general formula lll-Sp wherein o 3 is SH, borano, methylborano, dimethylborano, or cyanoborano.
• said boron analogues are referred to as Rp-analogues due to lower priority of boron compared to oxygen within Cahn-lngold-Prelog nomenclature rules.
• the cGMP analogue is for inhibition of a cyclic guanosine- 3’, 5’- monophosphate dependent protein kinase
• the preferred cGMP analogue is of general formula lll-Rp wherein o 3 is SH, borano, methylborano, dimethylborano, cyanoborano.
• Said boron analogues are referred to as Sp-analogues due to lower priority of boron compared to oxygen within Cahn-lngold-Prelog nomenclature rules.
• the cGMP analogue is for simultaneous activation of a cyclic guanosine- 3’, 5’- monophosphate dependent protein kinase and a cyclic guanosine- 3’, 5’- monophosphate gated ion channel
• the cGMP analogue is for simultaneous inhibition of a cyclic guanosine- 3’, 5’- monophosphate dependent protein kinase and a cyclic guanosine- 3’, 5’- monophosphate gated ion channel
• cyclic guanosine- 3’, 5’- monophosphate analogues are:
• 8- Methylthio- guanosine- 3', 5'- cyclic monophosphorothioate 8-MeS-cGMPS
• 8-MeS-cGMPS 8- Methylthio- guanosine- 3', 5'- cyclic monophosphorothioate
• 8-MeS-cGMPS 8- Methylthio- guanosine- 3', 5'- cyclic monophosphorothioate
• 8-MeS-cGMPS 8- Methylthio- guanosine- 3', 5'- cyclic monophosphorothioate
• 8-MeS-cGMPS 8- Methylthio- guanosine- 3', 5'- cyclic monophosphorothioate
• 8-MeS-cGMPS 8- Methylthio- guanosine- 3', 5'- cyclic monophosphorothioate
• More preferred cGMP analogues are 8-Br- cGMP, 8-Br-PET-cGMP, and 8-Br-(2-N)ET-cGMP, 8-Br-6-1 ,N 2 -But-cGMP, 8-Br-6-1 ,N 2 -But-cGMP, 8-Br-(3-Tp)ET-cGMP, 1-Bn-8-Br-cGMP, and their phosphorothioates, preferably their phosphorothioates.
• cGMP analogues are 8-pCPT-PET-cGMP, 8-Br-PET- cGMP, 8-pHPT-PET-cGMP, 8-pCPT-PET-cGMP, PET-cGMP, 8-Br-(2-N)ET-cGMP, (2-N)ET- cGMP, 8-Br-pMe-PET-cGMP, 8-Br-(3-Tp)ET-cGMP, PET-8-PAmdMT-cGMP, 8-plPrPT-PET- cGMP, 8-oAPT-PET-cGMP, PET-8-T-cGMP, 8-MeS-PET-cGMP, 8-Phe-PET-cGMP, 8-pCP-PET- cGMP, and pMeO-PET-cGMP, and their phosphorothioates, preferably their phosphorothioates, more preferably
• cGMP analogues are p-1 ,N 2 -Ac-8-Br-cGMP and 8-Br-6-1 ,N 2 -But-cGMP and their phosphorothioates, preferably their phosphorothioates.
• a most preferred cGMP analogue is 8-Br- PET-cGMP or its phosphorothioate, preferably its phosphorothioate.
• cGMP analogues consist of 8-Br-PET-cGMP, 8-Br-pMe-PET-cGMP, 8-Br-(3-Tp)ET- cGMP, 8-PAmdMT-cGMP, PET-8-PAmdMT-cGMP, 8-plPrPT-PET-cGMP, and 8-oAPT-PET- cGMP, and phosphorothioates thereof, preferably Rp-isomers thereof, preferably phorphorothioates thereof, most preferably Rp-isomers of phosphorothioates thereof.
• cGMP analogues are preferably Rp-isomers (for ease of reference, the Rp- isomer of e.g. PET-cGMP is denoted Rp-PET-cGMP, and a corresponding phosphorothioate is denoted PET-cGMPS).
• Rp-PET-cGMP a corresponding phosphorothioate
• PET-cGMPS a corresponding phosphorothioate
• the first step of the method is the provision of a guanosine analogue.
• guanosine itself can also be considered a guanosine analogue - it is not separately mentioned for legibility.
• the guanosine analogue can be synthetically prepared as part of the method, or it can be commercially obtained or otherwise sourced from elsewhere.
• phosphorous is introduced at the 5’-position of this guanosine analogue, which is later cyclized to form the cGMP analogue. It is preferred that variable moieties, such as h, R 1 , and R 2 , as later defined herein, remain constant starting from the end of step i).
• guanosine analogue (or the guanosine, as explained above) can also be a salt.
• a salt is preferably a pharmaceutically acceptable salt.
• Pharmaceutically acceptable salts are known in the art. Preferred salts are acid addition salts. Other preferred salts are base addition salts.
• pharmaceutically acceptable salts preferably include salts derived from inorganic bases such as Li, Na, K, Ca, Mg, Fe, Cu, Zn and Mn; salts of organic bases such as N,N’-diacetylethylenediamine, glucamine, triethylamine, choline, dicyclohexylamine, benzylamine, (tri)alkylamine, thiamine, guanidine, diethanolamine, alphaphenylethylamine, piperidine, morpholine, pyridine, hydroxyethylpyrrolidine, hydroxyethylpiperidine, and the like.
• inorganic bases such as Li, Na, K, Ca, Mg, Fe, Cu, Zn and Mn
• salts of organic bases such as N,N’-diacetylethylenediamine, glucamine, triethylamine, choline, dicyclohexylamine, benzylamine, (tri)alkylamine,
• Such salts also include amino acid salts such as glycine, alanine, cystine, cysteine, lysine, arginine, phenylalanine, guanidine, etc.
• Such salts may include acid addition salts where appropriate, which are for example sulphates, nitrates, phosphates, perchlorates, borates, hydrohalides such as HCI or HBr salts, acetates, trifluoroacetates, tartrates, maleates, citrates, succinates, palmoates, methanesulphonates, tosylates, benzoates, salicylates, hydroxynaphthoates, benzenesulfonates, ascorbates, glycerophosphates, ketoglutarates and the like.
• Preferred salts are HCI salts, formic acid salts, acetic acid salts, triethylammonium (TEAH+) salts, sodium salts, and trifluoroacetic acid salts. More preferred salts are TEAH+ salts and sodium salts.
• TEAH+ salts are sodium salts.
• TEAH+ salts are sodium salts.
• phrases “pharmaceutically acceptable” refers to compounds or compositions that are physiologically tolerable and do not typically produce allergic or similar untoward reactions, including but not limited to gastric upset or dizziness when administered to mammals. A skilled person can discern what is or is not pharmaceutically acceptable.
• the guanosine analogue can also be a hydrate or a solvate.
• a hydrate refers to a solvate wherein the solvent is water.
• solvate refers to a crystal form of a substance which contains solvent.
• Solvates are preferably pharmaceutically acceptable solvates and may be hydrates or may comprise other solvents of crystallization such as alcohols, ether, and the like. Accordingly, a crystal can be a hydrate or a solvate, and crystallization can yield a hydrate or a solvate.
• the guanosine analogue is preferably of general formula (I) or a salt thereof: wherein: h is H, halogen, or Q; preferably, h is H, F, Br, Cl, or Q, more preferably it is H, Br, or Q; in highly preferred embodiments, h is H; in highly preferred embodiments, h is Br; in highly preferred embodiments, h is H or Br; in highly preferred embodiments, h is Q; in most preferred embodiments, h is H or Br or Q;
• X 1 and X 2 are each independently chosen from H or p'; preferably X 1 is H, more preferably it is H before the step wherein the cyclic phosphorous oxoacid diester is formed as described later herein; preferably, prior to formation of the 5’-phosphorous oxoacid ester, and X 2 is p'; most preferably, X 1 is H and X 2 is p'; p' is in each instance independently chosen from a hydroxyl protective group; Hydroxyl protective groups are known in the art and can protect oxygen atoms in hydroxyl moieties. Examples of suitable hydroxyl protective groups are extensively described in the art, e.g. by P.G.M. Wuts and T.W.
• Suitable protective groups are methoxymethyl (MOM), tetrahydropyranyl (THP), f-butyl (tBu), allyl (all), benzyl (Bn), (tri)alkylsilyl (such as f-butyldimethylsilyl (TBDMS), triisopropylsilyl (TIPS), or f-butyldiphenylsilyl (TBDPS), a preferred (tri)alkylsilyl is a trialkylsilyl), and acyl (such as acetyl (Ac), pivalyl (Pv), or benzoyl (Bz))., more preferably it is triisopropylsilyl (TIPS).
• Preferred groups for p' are THP, (tri)alkylsilyl, and acyl. More preferred groups for p' are THP and (tri)alkylsilyl (preferably TIPS), most preferably p' is (tri)alkylsilyl (preferably TIPS), p' is always attached to oxygen, and multiple instances p' can together form a single protective group that protects more than one hydroxyl group, as is known in the art. Examples of such multivalent protective groups are acetonides and benzylidene acetals. In preferred embodiments, when two moieties protected by p' are attached to the same carbon atom or to adjacent carbon atoms, the two instances of p' together form a single multivalent protective group.
• Heterocyclyl in the context of the invention, is an optionally unsaturated heterocycle having 3, 4, 5, 6, 7, 8, or 9 carbon atoms.
• heterocycle is optionally substituted as described for ar, and carbon atoms in the optional substitutions do not count towards C3-9.
• Heteroatoms are preferably selected from O, S, and N.
• the heterocyclyl has at most 3 heteroatoms, more preferably at most 2, most preferably at most 1 .
• Heterocyclyl preferably has at least 1 , more preferably at least 2 heteroatoms.
• Preferred examples of heterocyclyl are piperidinyl, piperazinyl, morpholinyl, tetrahydrofuranyl, pyrazollyl, and pyrrolidinyl.
• a styrylene moiety is formed, and accordingly ar is phenyl.
• ar is in each instance independently a 5- or 6-membered aromatic or heteroaromatic ring, preferably phenyl or 2-furanyl, wherein each instance of ar is individually optionally substituted with halogen, -OH, -SH, -NH 2 , -NO 2 , -OCH3, -CH 3 , -CH2CH3, -CH(CH 3 )2, or-CF 3 , and is optionally fused with a second instance of ar, preferably forming a naphthyl moiety; preferably no more than two instances of ar are comprised in such a fused moiety.
• ar is fused to a further instance of ar.
• ar is 6-membered.
• ar is unsubstituted.
• Preferred examples of ar are phenyl, furanyl, pyridinyl, imidazolyl, tetrazolyl, triazolyl, thiophenyl, benzothiazolyl, indolyl, 4-methylphenyl, 3-thiophenyl, and naphthyl.
• a higly preferred embodiment of ar is 4-methylphenyl.
• Q is -(CH 2 )n-S-(CH 2 )n-H, -S-(CH 2 )n-OH, -S-(CH 2 )n-NH 2 , -(CH 2 )n-O-(CH 2 )n-H, -O-(CH 2 )n-OH, -O-(CH 2 )n-NH 2 , -O-C(CH 3 )3, -O-CH(CH 3 )2, -(CH 2 )n-N(-[CH 2 ]nH)2, -NH-(CH 2 )nNH 2 , -NH-(CH 2 ) n OH, - (CH 2 )n-Nc 1 c 2 wherein c 1 and c 2 together with the N to which they are attached form a 3 to 8 membered heterocycle or wherein c 1 is H and c 2 is a 3 to 8 membered heterocycle, -(CH2)n-H, -N3, -CF 3
• Q is -(CH 2 )n-S-(CH 2 )n-H, -S-(CH 2 )n-OH, -S-(CH 2 )n-NH 2 , -(CH 2 )n-O-(CH 2 )n-H, -O- (CH 2 ) n -OH, -O-(CH 2 )n-NH 2 , -O-C(CH 3 )3, -O-CH(CH 3 )2, -(CH 2 )n-N(-[CH 2 ]nH)2, -NH-(CH 2 )nNH 2 , -NH- (CH 2 )nOH, -(CH 2 )n-Nc 1 c 2 wherein c 1 and c 2 together with the N to which they are attached form a 3 to 8 membered heterocycle or wherein c 1 is H and c 2 is
• -(CH 2 )n-S-(CH 2 )n-H is preferably -S-(CH 2 )n-H or -(CH 2 ) n -SH.
• n is preferably 2, 3, 4, 5, or 6.
• n is preferably 2, 3, 4, 5, or 6.
• -(CH2)n-O-(CH2)n-H is preferably -(CH2)n-OH or -O-(CH2)n-H.
• n is preferably 2, 3, 4, 5, or 6.
• -O- (CH2)n-NH2 is preferably 2, 3, 4, 5, or 6.
• -(CH2)n-N(-[CH2]nH)2 is preferably -(CH2)n-NH2 wherein n is at least 2, or -(CH2)n-N(-[CH2]nH)2-wherein each instance of n is at least 2..
• n is preferably 2, 3, 4, 5, or 6.
• n is preferably 2, 3, 4, 5, or 6.
• -(CH2)n-Nc 1 c 2 n is preferably 2, 3, 4, 5, or 6.
• c 1 and c 2 together with the N to which they are attached form a 3 to 8 membered heterocycle, more preferably a 4 to 6 membered heterocycle, most preferably a 5 or 6 membered heterocycle.
• c 1 is H and c 2 is a 3 to 8 membered heterocycle, more preferably a 4, 5, or 6 membered heterocycle, most preferably a 5 or 6 membered heterocycle.
• n is preferably 0, 1 , 2, 3, 4, 5, or 6, more preferably 1 , 2, 3, or 4, even more preferably 1 or 2, most preferably 1.
• n is preferably 0, 1 , 2, 3, 4, 5, or 6, more preferably 0, 1 , 2, or 3, even more preferably 0, 1 or 2, most preferably 0 or 2.
• n is preferably at least 2.
• n is preferably at least 2.
• at least 1 -H may be replaced by a halogen, more preferably fluorine, and preferably at most three instances of-H are replaced by halogen; optionally, all instances of H are replaced by F.
• n is not 0 when this would result in directly linked heteroatoms, more preferably it is not 0 or 1 .
• n is at most 6.
• Linkers are known in the art.
• the structure of a linker is such that the linker can be easily chemically attached to a compound used in the invention to form a linker compound, and so that the resulting linker compound can be easily conjugated to a further substance such as a polypeptide or a surface.
• the choice of linker can influence the stability of such eventual conjugates when in circulation or when on a surface.
• Linkers may be cleavable or non-cleavable.
• Cleavable linkers comprise moieties that can be cleaved e.g. when exposed to lysosomal proteases or to an environment having an acidic pH.
• Suitable cleavable linkers are known in the art and comprise e.g.
• cleavable linker may comprise a selfimmolative moiety such as an co-amino aminocarbonyl cyclization spacer, see Saari et al. J. Med. Chem., 1990, 33(1), 97-101 , or a -NH- CH2-O- moiety. Cleavage of the linker can make the compound more available to the surrounding medium. Non-cleavable linkers can still effectively release the compound according to the invention, for example after a conjugated polypeptide is degraded in the lysosome.
• Non-cleavable linkers include e.g. succinimidyl-4-(/V-maleimidomethyl(cyclohexane)-1 -carboxylate and maleimidocaproic acid and analogues thereof.
• h is H or halogen or Q, preferably H or Br or Q, more preferably Br or Q, most preferably Br;
• X 1 is H and X 2 is p'; p' is selected from the group consisting of methoxymethyl (MOM), tetrahydropyranyl (THP), f-butyl (tBu), allyl (all), benzyl (Bn), (tri)alkylsilyl (such as f-butyldimethylsilyl (TBDMS), triisopropylsilyl (TIPS), or f-butyldiphenylsilyl (TBDPS)), acyl (such as acetyl (Ac), pivaloyl (Pv), or benzoyl (Bz)), preferably from THP, (tri)alkylsilyl, and acyl;
• h is Br
• X 1 is H and X 2 is p'
• p' is triisopropylsilyl (TIPS)
• X 2 is p' and X 1 is H, because this facilitates chemoselective introduction of the 5’-monophosphorous oxoacid ester analogue.
• the inventors surprisingly found that protection at X 1 is of less influence than protection at X 2 . Accordingly, in preferred embodiments is provided the method according to the invention, wherein X 1 is H and X 2 is p', wherein the guanosine analogue of general formula (I) or salt thereof is provided by the steps of: la) providing an unprotected guanosine analogue of general formula (pl) or a salt thereof: wherein h, R 1 , and R 2 are as defined for general formula I.
• a precursor of the guanosine analogue to be converted in step ii) is provided.
• This precursor is characterized in that it has H at both X 1 and X 2 , and therefore it is referred to as an unprotected guanosine analogue.
• the unprotected guanosine analogue is protected using a (tri)alkylsilylhalide, leading to X 2 becoming a (tri)alkylsilyl protecting group, which is a preferred protecting group for p’. Additionally, the 5’-OH group can become protected during this reaction step. Surprisingly, X 1 was found to remain H.
• the 5’- and 2’-protected guanosine analogue can be conveniently isolated by crystallization, which is done in preferred embodiments.
• the reaction is preferably performed in an aprotic polar solvent such as DMF, pyridine, tetramethylurea, dimethylacetamide, or NMP, more preferably DMF or NMP.
• the reaction is preferably performed in the presence of a mild base, more preferably a mild organic base such as imidazole, pyridine, trialkylamine such as trimethylamine, N-methylmorpholine, or N-methylimidazole, more preferably imidazole.
• a mild base more preferably a mild organic base such as imidazole, pyridine, trialkylamine such as trimethylamine, N-methylmorpholine, or N-methylimidazole, more preferably imidazole.
• Progress of the reaction is preferably monitored using an analytical technique such as a chromatographic technique such as TLC or HPLC.
• TLC chromatographic technique
• After substantially all X 2 have been protected the reaction is preferably quenched, such as by addition of an excess of water, such as 10 equivalents (equiv.).
• the quenched reaction is preferably extracted into an aprotic organic solvent, preferably of low polarity such as toluene, esters such as isopropyl acetate and butyl acetate, ethers such as te/Y-butyl methyl ether, or benzene, more preferably toluene, after which it is washed with aqueous phases.
• the reaction product is preferably isolated by crystallization, preferably from an organic solvent that is not methanol, more preferably from an aprotic organic solvent, even more preferably from a polar one, such as ethyl acetate or propyl acetate, most preferably from isopropyl acetate.
• the crystallization is preferably seeded, more preferably using the desired product to be crystallized. After crystallization, which is preferably left for at least 4, more preferably at least 8, even more preferably at least 12 hours, the crystals are preferably washed and/or dried. Washing is preferably performed using the same solvent as was used for the crystallization. Drying is preferably performed in vacuum, more preferably at elevated temperature such as at about 40-80 °C, preferably at about 50-70 °C. lc) selectively deprotecting the multiply protected guanosine analogue to obtain the guanosine analogue of general formula (I) wherein X 1 is H and X 2 is p'.
• general formula (I) wherein X 1 is H and X 2 is p'.
• this step the difference in reactivity of the 2’- and 5’- protected positions is used, and by using mild reaction conditions such as aqueous TFA the protected 5’-OH is selectively deprotected.
• This step can be performed using any combination of THF and/or water with an acid, preferably TFA, but it is preferably performed in an aprotic organic solvent, preferably in a polar one such as THF or 1 ,4-dioxane.
• Deprotection is preferably done using a strong acid, preferably TFA, preferably using about 7 to 13 such as 10 volumes of the solvent, about 1 to 3 such as 2 volumes water, and about 0.2 to 1 such as 0.45 volumes TFA.
• the reaction is preferably monitored using a suitable analytical technique, such as chromatography such as HPLC. Monitoring is beneficial because it can detect overdeprotection wherein the 2’-position might also deprotect.
• a suitable analytical technique such as chromatography such as HPLC. Monitoring is beneficial because it can detect overdeprotection wherein the 2’-position might also deprotect.
• the reaction is preferably quenched by addition of a base, preferably a mild nitrogen-based base such as ammonia, or a suitable amine base such as a trialkylamine, or an inorganic base such as a carbonate or bicarbonate, more preferably ammonia or an amine base as this avoids evolution of gases, most preferably ammonia as it is volume efficient.
• the quenched crude reaction mixture is evaporated and resuspended in a mixture wherein fully deprotected side products are not soluble, such as in a mixture of dichloromethane or chloroform with a small amount of water (about 10-20 such as 15 volumes of the for example dichloromethane versus about 1 to 3 such as 2 volumes water), or such as acetone.
• the resulting thin slurry is preferentially filtered to remove possible insoluble contaminants.
• the organic phase of the filtrate is preferably separated after which it can be evaporated to obtain a residue.
• the residue is preferably triturated using a polar organic solvent, preferably an aprotic one such as acetonitrile or ethyl acetate, more preferably acetonitrile.
• a polar organic solvent preferably an aprotic one such as acetonitrile or ethyl acetate, more preferably acetonitrile.
• the remaining solids are preferably washed using the same solvent as was used for trituration, after which the product is preferably dried such as vacuum dried.
• ld) optionally isolating the obtained guanosine analogue of general formula (I) wherein X 1 is H and X 2 is p' by crystallization or preferably trituration.
• p’ is (tri)alkylsilyl, and the 2’- protected guanosine analogue is conveniently isolated by crystallization. Isolation is preferably performed as described above in step Ic).
• ar is as defined above, such as phenyl or furanyl, preferably phenyl.
• the reactant is phenacylbromide.
• a strong base is added, preferably a strong organic base such as DBU or tetramethylguanidine, more preferably DBU, preferably about 1-5 such as about 2.5 equiv., preferably over a period of time such as over about 10-60 minutes such as about 30 minutes.
• the reaction is preferably neutralized, more preferably by addition of an acid, preferably a weak acid, more preferably an organic acid such as acetic acid.
• the product is preferably precipitated from the crude reaction mixture by addition of for example water such as about 10 volumes.
• the precipitated product is preferably isolated by filtration and is preferably washed such as with aqueous DMSO or with water, after which the solids are preferably dried such as vacuum dried.
• the solid is then triturated using a suitable aprotic polar organic solvent such as acetonitrile or THF, more preferably acetonitrile, after which the product is preferably dried such as vacuum dried.
• Vacuum drying is preferably performed at elevated temperature such as at about 70 °C.
• the guanosine analogue that is provided in step i) is contacted with a phosphorous oxoacid derivative to obtain a guanosine 5’-monophosphorous oxoacid ester analogue.
• the phosphorous oxoacid derivative is preferably a phosphorylating agent or a phosphonylating agent, and the term phosphorous oxoacid derivative should not be so narrowly construed as to only encompass actual oxoacids - it is envisioned that thio-analogues and derivatives such as PCh are also encompassed. Such agents are known in the art.
• the agents are for introducing phosphorous oxoacid ester at the 5’-position of the guanosine analogue to form a GMP analogue.
• the phosphorous oxoacid derivative is a phosphorylating agent.
• the phosphorous oxoacid derivative is a phosphonylating agent.
• the phosphorous oxoacid derivative of step ii) is of general formula (P): M o 1 - P — o 2 (P) i o 3 wherein:
• M is S or O or is absent; in preferred embodiments, M is S or O, more preferably O; in other preferred embodiments, M is absent; o 1 and o 2 are each independently selected from halogen, -O-Ci-shydrocarbon, -S-Ci- shydrocarbon, -NH-Ci-shydrocarbon, borano, methylborano, dimethylborano, cyanoborano, and - N(Ci-shydrocarbon)2; and o 3 is H or is as defined for o 1 ; or o 1 and o 3 together form a chiral auxiliary that is preferably a C2-i2hydrocarbon.
• Ci-shydrocarbon in this context, preferably forms a suitable leaving group.
• a hydrocarbon can comprise heteroatoms, and can be optionally substituted with halogen, preferably with fluorine.
• o 1 represents a suitable leaving group such as halogen, -O-Ci- shydrocarbon such as -O-CeFs, -S-Ci-shydrocarbon such as -S-CsFs, -NH-Ci-shydrocarbon, and - N(Ci-shydrocarbon)2.
• o 2 represents a suitable leaving group such as halogen, -O-Ci-shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, and -N(Ci- shydrocarbon)2.
• o 1 and o 2 both represent a suitable leaving group.
• o 1 and o 2 represent the same moiety.
• suitable leaving groups are phenol, pentafluorophenol, imidazole, triazole, diisopropylamine, and halogen such as chlorine or bromine, more preferably chlorine. It is understood that for N(Ci-shydrocarbon)2 the two hydrocarbons can together form a cyclic structure comprising the nitrogen to which they are attached, such as when imidazole is formed.
• a chiral auxiliary as is known in the art (see for example Knouse et al., 2018, Science, DOI: 10.1126/science.aau3369), is a moiety that promotes eventual cyclisation in a given stereochemical configuration, because the chiral auxiliary forms a chiral cyclic structure around the central phosphorous atom of general formula (P).
• a chiral auxiliary depicted here as a biradical moiety bridging between the positions where o 1 and o 3 are attached, with underscores used to emphasize chiral centers, is -O-CH(C*)-C(C**)(CHs)-S-, wherein C* and C** together with the carbon atoms to which they are attached form a cyclic structure by representing -CH2-CH(2- propene)-CH2-CH2-.
• M is preferably S or O, more preferably S.
• Preferred compounds of general formula (P) are diphenylphosphite, dimethylphosphite, diethylphosphite, diisopropylphosphite, dihalophosphite such as dichlorophosphite, di(pentafluorophenyl)phosphite, diphenylthiophosphite, dimethylthiophosphite, diethylthiophosphite, diisopropylthiophosphite, dihalothiophosphite such as dichlorothiophosphite, di(pentafluorophenyl)thiophosphite, di(diisopropylamino)methoxiphosphite ([(iPr)2N]2P[OMe]), [(iPr) 2 N] 2 P[OEt], CI 2 P(S)(OMe), CI 2 P(S)(OEt), CI
• Preferred phosphonylating agents are diphenylphosphite, dimethylphosphite, diethylphosphite, diisopropylphosphite, dihalophosphite such as dichlorophosphite, di(pentafluorophenyl)phosphite, diphenylthiophosphite, dimethylthiophosphite, diethylthiophosphite, diisopropylthiophosphite, dihalothiophosphite such as dichlorothiophosphite, di(pentafluorophenyl)thiophosphite, [(iPr)2N]2P[OMe], and [(iPr)2N]2P[OEt], more preferred are diphenylphosphite, diphenylthiophosphite, and [(iPr)2N]2P[OMe], most preferred is di
• Contacting of the phosphorous oxoacid derivative with the guanosine analogue is preferably performed under conditions conducive to formation of a guanosine 5’-monophosphorous oxoacid ester analogue.
• the contacting is preferably performed in an aprotic solvent, more preferably in an aprotic solvent of relatively low polarity such as dichloromethane or chloroform.
• Contacting is preferably performed in the presence of a mild base, preferably a non-nucleophilic one such as pyridine, lutidine, imidazole, or other nitrogenous bases with a pKa of about 4-7, more preferably of about 5-7.
• Contacting is preferably performed using an excess of phosphorous oxoacid derivative, preferably using about 2 to about 5 equiv. such as about 3 equiv. of reactant.
• the reaction is preferably quenched using for example a basic aqueous solution, such as an aqueous (tri)alkylamine solution such as 1 volume of water and 1 volume of trimethylamine, which is then preferably left for about 10 to 60 minutes such as for about 30 minutes.
• the organic phase is preferably washed afterwards, such as with water.
• the organic phase is then preferably dried, such as by evaporation of solvent, preferably followed by coevaporation, such as co-evaporation with toluene, ethyl acetate, or isopropanol, preferably with ethyl acetate and/or isopropanol.
• the product of this contacting is a guanosine 5’-monophosphorous oxoacid ester analogue.
• definitions and preferred embodiments for h are preferably as defined for compounds of general formula (I).
• definitions and preferred embodiments for R 1 are preferably as defined for compounds of general formula (I).
• definitions and preferred embodiments for R 2 are preferably as defined for compounds of general formula (I).
• definitions and preferred embodiments for X 1 are preferably as defined for compounds of general formula (I).
• definitions and preferred embodiments for X 2 are preferably as defined for compounds of general formula (I).
• o 3 is H and o 1 is -OH, -O-Ci-shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, borano, methylborano, dimethylborano, cyanoborano, or -N(Ci- shydrocarbon)2, more preferably -O-Ci-shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, or -N(Ci-shydrocarbon)2.
• o 1 and o 3 are both -OH, -O-Ci- shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, borano, methylborano, dimethylborano, cyanoborano, or -N(Ci-shydrocarbon)2, more preferably -O-Ci-shydrocarbon, -S-Ci-shydrocarbon, - NH-Ci-shydrocarbon, or -N(Ci-shydrocarbon)2.
• o 1 and o 3 together form a chiral auxiliary as defined above. Most preferably, o 1 is -OH and O 3 is H.
• references to a compound from the above list is intended to also refer to a salt of such a compound, wherein salts are as defined elsewhere herein.
• the free base compound is referenced.
• a salt is referenced.
• the compound is selected from compounds 1-16.
• the compound is selected from compounds 17-32.
• the compounds are selected from 1 , 10, 11 , 17, 26, and 27, more preferably from 1 , 10, and 11 , alternatively more preferably from 17, 26, and 27.
• the compounds are selected from 6, 10-16, 22, and 26-32, more preferably from 6 and 10-16, alternatively more preferably from 22 and 26-32.
• the compounds are selected from 6, 10-13, 15, 16, 22, 26-29, 31 , and 32, more preferably from 6, 10-13, 15, and 16, alternatively more preferably from 22 and 26-29, 31 , and 32.
• the compounds are selected from 1-5, 7-9, 17-21 , and 23-25, more preferably from 1-5 and 7-9, alternatively more preferably from 17-21 and 23-25.
• Very highly preferred compounds are compound 10 and 26, most preferably compound 26.
• Other very highly preferred compounds are compounds 10, 35, 36, and 40-43 and their mono-H-phosphonates, more preferably their mono-H-phosphonates.
• This intermediate is never isolated in cGMP production methods known in the art, while purification of this intermediate was found to have advantageous effects, such as increase in cyclisation yield and improved control over the chirality of the cyclisation product.
• the guanosine 5’-monophosphorous oxoacid ester analogue is a salt when it is crystallized, more preferably it is a salt wherein the counterion is a hydronated organic base, most preferably wherein the counterion is a hydronated (tri)alkylamine such as TEAH+.
• the guanosine 5’-monophosphorous oxoacid ester analogue is isolated by crystallization, preferably from an aprotic organic solvent, more preferably from a polar one, such as ethyl acetate or propyl acetate or THF or te/Y-butyl methyl ether, most preferably from ethyl acetate.
• the crystallization is preferably seeded, more preferably using the desired product to be crystallized. After crystallization, which is preferably left for at least 4, more preferably at least 8, even more preferably at least 12 hours, the crystals are preferably washed and/or dried. Crystallization is preferably at room temperature.
• Washing is preferably performed using the same solvent as was used for the crystallization. Drying is preferably performed in vacuum, more preferably at elevated temperature such as at about 40-80 °C, preferably at about 50-70 °C. In preferred embodiments the obtained crystal is a solvate.
• Preferred crystals comprise substantially pure product, more preferably having a purity of at least 80, 85, 90, 91 , 92, 93, 94, 95, 96, 97, 98, 99, or 100%, even more preferably of at least 95, 96, 97, 98, 99, or 100%, most preferably of at least 97%, optionally more.
• the 5’-phosphate monoester isolated in step iii) can advantageously be used to continue synthesis of a cGMP analogue.
• preferred methods according to the invention further comprise a step: iv) cyclizing the guanosine 5’-monophosphorous oxoacid ester analogue obtained in step ii) (and crystallized in step iii) to obtain a cyclic guanosine-3', 5'-monophosphate (cGMP) analogue, wherein said cyclisation is preferably performed in the presence of a sterically hindered base. It stands to reason that if X 1 is not H, this step is preferably preceded by conversion of X 1 to H by deprotecting the corresponding protected hydroxyl moiety.
• a cGMP analogue is preferably is of general formula (III) or a salt thereof: wherein h, X 2 , R 1 , and R 2 are as defined above, preferably as defined for compounds of general formula (II).
• X 2 is p', more preferably it is (tri)alkylsilyl such as TIPS, o 3 is as defined for compounds of general formula (II), preferably o 3 is H.
• o 3 is -OH, -O-Ci-shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, borano, methylborano, dimethylborano, cyanoborano, or -N(Ci-shydrocarbon)2, most preferably -OH.
• definitions and preferred embodiments for h are preferably as defined for compounds of general formula (II).
• definitions and preferred embodiments for R 1 are preferably as defined for compounds of general formula (II).
• definitions and preferred embodiments for R 2 are preferably as defined for compounds of general formula l(l).
• definitions and preferred embodiments for X 2 are preferably as defined for compounds of general formula (II).
• Cyclisation can be performed using methods known in the art.
• cyclisation is performed in the presence of a coupling reagent.
• cyclisation is performed in the presence of a sterically hindered base or pyridine, more preferably of a sterically hindered mild base or pyridine, even more preferably of a sterically hindered mild base.
• a coupling reagent and a sterically hindered base are used.
• the cyclisation is preferably performed under dilute conditions, such as at most about 200 g/L, preferably at most about 100g/L, more preferably at most about 80g/L, even more preferably at most about 60g/L such as about 50g/L, expressed as weight of 5’-monophosphorous oxoacid ester analogue per liter of solvent.
• the solvent is preferably an aprotic solvent, more preferably a slightly polar one such as dichloromethane or chloroform or acetonitrile, even more preferably chloroform or dichloromethane.
• the base is preferably present in excess, such as at about 2-9 equiv., more preferably about 4-6 equiv., such as about 5 equiv.
• the coupling reagent is preferably present in excess, such as at about 1 .1-5 equiv., more preferably about 1 .2-3 equiv., such as about 1 .5 equiv.
• the base is added to the dilute 5’-monophosphorous oxoacid ester analogue solution first, after which the coupling reagent is added.
• the reaction is preferably allowed to proceed for at least 30 minutes, more preferably at least 1 hour, most preferably about 2 hours or more.
• suitable sterically hindered bases are lutidine, picoline, collidine, N,N-dimethylaniline, N-methyl-morpholine, and quinolone, more preferably lutidine.
• Further preferred sterically hindered bases have a pKa of about 4-7, more preferably of about 5-7.
• Suitable coupling reagents are widely known in the art.
• Preferred examples of suitable coupling reagents are aryl sulfonic acid derivatives, diester chlorophosphates, carbodiimides, and acyl halides, such as 0-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HBTU), bis(2-oxo-3-oxazolidinyl)phosphinic chloride (BOP-CI), 2-chloro-4,6-dimethoxy-1 ,3,5- triazine (CDMT), (chloromethylene)dimethyliminium chloride (Vilsmeier reagent), N- (dimethylaminopropyl)-N'-ethyl-carbodiimide (EDC), carbonyl diimidazole (CDI), propylphosphonic anhydride (T3P), diethyl chlorophosphate, dicycl
• acyl halides are used, of which acyl chlorides are most preferred, such as propyl chloride, benzoyl chloride, ethyl chloroformate, isobutyl chloroformate, and pivaloyl chloride.
• acyl chlorides are most preferred, such as propyl chloride, benzoyl chloride, ethyl chloroformate, isobutyl chloroformate, and pivaloyl chloride.
• Pivaloyl chloride is most highly preferred.
• the cGMP analogue can be isolated by washing the organic phase, preferably with water, after which it is preferably diluted with an aprotic polar solvent such as acetonitrile.
• the organic phase is evaporated.
• the obtained crude product is preferably further purified by resuspending the crude solids in an aprotic polar solvent such as acetonitrile, after which solids are filtered out.
• the filtrate is then preferably concentrated in vacuo, after which it is preferably redissolved in an aprotic polar solvent such as acetonitrile.
• a crude solution is then preferably treated by addition of an excess of an ether solvent, preferably a tert-butyl ether solvent such as tert-butyl methyl ether (TBME).
• the excess is preferably at least 5 volumes, more preferably at least 10 volumes such as about 12 volumes.
• the resulting composition is preferably left for at least about 4 hours, more preferably at least about 8 hours, after which solvent is removed, preferably by decantation and/or evaporation.
• the resulting residue can be an oil.
• the resulting residue is preferably dried in vacuo, after which it is preferably triturated using an ether solvent, preferably a tert-butyl ether solvent such as TBME.
• the cGMP analogue is not isolated prior to any further reaction steps.
• Rp- and Sp-stereoisomers of general formula (III) are shown below, and are of general formula (lll-Rp) and (lll-Sp) respectively.
• a compound of general formula (III) is of general formula (lll- Rp). Because for different applications the different diastereomers can be relevant, in other preferred embodiments a compound of general formula (III) is of general formula (lll-Sp). In compounds of general formula (lll-Rp) or (lll-Sp), h, X 2 , R 1 , and R 2 are preferably as defined above, more preferably as defined for compounds of general formula (III).
• X 2 is p', more preferably (tri)alkylsilyl, most preferably TIPS, o 3 is preferably as defined for compounds of general formula (II), more preferably it is as defined there but not -OH, even more preferably o 3 is H or SH.
• o 3 is H.
• the corresponding diastereomer is present in a diastereomeric excess of at least 2:1 , more preferably of at least 3:1 , even more preferably at least 4:1 , more preferably still at least 5:1 , even more preferably still at least 6:1 , still more preferably at least 7:1 , most preferably at least about 8:1 .
• the compound when a compound of general formula (III) and/or of general formula (lll-Rp) or (lll-Sp) is obtained after step iv), the compound has a purity of at least 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or more percent. More preferably purity is at least 70%, even more preferably at least 75%, more preferably still at least 80%, even more preferably still at least 85%, still more preferably at least 90%. Purity can be assayed using known techniques, preferably it is assayed using HPLC.
• Preferred compounds of general formula (III) are a salt thereof, more preferably a salt wherein the counterion is a hydronated organic base, most preferably wherein the counterion is a hydronated (tri)alkylamine such as TEAH+.
• Preferred compounds of general formula (lll-Rp) are a salt thereof, more preferably a salt wherein the counterion is a hydronated organic base, most preferably wherein the counterion is a hydronated (tri)alkylamine such as TEAH+.
• Preferred compounds of general formula (lll-Sp) are a salt thereof, more preferably a salt wherein the counterion is a hydronated organic base, most preferably wherein the counterion is a hydronated (tri)alkylamine such as TEAH+.
• the method according to the invention comprises a step v): v) contacting the cGMP analogue with a sulfurizing agent to obtain a thiolated cGMP analogue of general formula (III) wherein o 3 is -SH or -S-Ci-i2hydrocarbon, preferably -SH.
• the cGMP analogue is of general formula (lll-Rp).
• the cGMP analogue is of general formula (lll-Sp).
• Step v) is preferred when M is O in a guanosine 5’-monophosphorous oxoacid analogue of general formula (II).
• M is S, preferably step v) is not comprised in the method.
• Sulfurizing agents are known in the art.
• Preferred examples of sulfurizing agents are sulfur, phenylacetyldisulfide and A/-(alkyl-thio)-succinimides such as /V-methylthio-succinimide. N- ethylthio-succinimide, and /V-propylthio-succinimide. Sulfur is most preferred.
• Preferred Ci- i2hydrocarbons are Ci-shydrocarbons, more preferably Ci-4hydrocarbons.
• Suitable sulfur introduction comprises using electrophilic sulfur, preferably the use of a sulfurizing agent as described above, followed by oxidation (i.e. an increase in oxidation state), preferably using an oxidizing agent as described below. Use of nucleophilic sulfur is not preferred.
• the contacting is performed in the presence of a base, more preferably a (tri)alkylamine base such as triethylamine.
• a base more preferably a (tri)alkylamine base such as triethylamine.
• the reaction is preferably allowed to proceed for at least 30 minutes, more preferably at least 60 minutes, most preferably at least 90 minutes. Progress of the reaction is preferably assessed using known techniques such as HPLC.
• the method according to the invention comprises a step v-O): v-O) contacting the cGMP analogue with an oxidizing agent to obtain a cGMP analogue of general formula (III) wherein o 3 is -OH.
• oxo-derivatives are activators of PKG and not inhibitors thereof, such as the thiophosphates wherein o 3 comprises S.
• Oxidizing agents are known in the art.
• Step v-O) is preferably performed under anhydrous conditions.
• suitable oxidizing agents for step v-O) are peroxides such as hydrogen peroxide, bis(trimethylsilyl)peroxide, t-butyl hydroperoxide, cumene hydroperoxide, iodine, and alkylamino-oxides such as N-methylmorpholine N-oxide.
• the agent can be catalytic, such as Pd/C powder.
• phosphite oxidation to phosphates are known, for example from Hayakawa et al. (Tet. Lett.
• the compound when a compound of general formula (III) and/or of general formula (lll-Rp) or (lll-Sp) is obtained after step v) or v-O), the compound has a purity of at least 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or more percent. More preferably purity is at least 70%, even more preferably at least 75%, more preferably still at least 80%, even more preferably still at least 85%, still more preferably at least 90%. Purity can be assayed using known techniques, preferably it is assayed using HPLC.
• the cGMP analogues produced by the method of the invention are preferably deprotected, which in the context of this invention means that produced cGMP analogues of general formula (III) preferably have X 2 is H. Therefore, in preferred embodiments is provided the method according to the invention wherein X 2 is p', the method further comprising the step of: vi) deprotecting the hydroxyl moiety that is protected by X 2 to obtain a deprotected cGMP analogue.
• a deprotected cGMP analogue is a cGMP analogue of general formula (III) wherein X 2 is H.
• deprotection can be performed at acidic conditions, for example at pH ⁇ 1 , optionally at elevated temperatures.
• Deprotection can also preferably be performed in the presence of fluoride, for example using HF, (tri)alkylamine HF, or TBAF.
• fluoride for example using HF, (tri)alkylamine HF, or TBAF.
• deprotection in the presence of fluoride is preferred, more preferably using (tri)alkylamine HF such as triethylamine HF, preferably at 10-50 vol.-% of the solution, more preferably at 20-40 vol.-% such as at about 33 vol.-%.
• Deprotection is preferably performed in an aprotic solvent, more preferably a polar aprotic solvent that is a cyclic ether, such as tetrahydrofuran or 1 ,4-dioxane.
• the reaction is preferably allowed to proceed for about a day, more preferably about 2 days, even more preferably about 3 days. Standard analytical techniques such as HPLC can be used to monitor reaction progress.
• Precipitated deprotected product is preferably isolated by filtration, after which it is preferably washed, more preferably using the solvent that was used for deprotection. Afterwards the product is preferably dried, such as under vacuum. Products obtained this way are a fluoride complex of the deprotected cGMP analogue.
• a produced cGMP analogue is in a complex with fluoride.
• This cGMP analogue fluoride complex preferably has a purity, as assayed for the cGMP analogue, of at least 60, 65, 70, 75, or 80 percent. More preferably purity is at least 70%, even more preferably at least 75%, more preferably still at least 80%. Purity can be assayed using known techniques, preferably it is assayed using HPLC.
• This compound is preferably a salt, more preferably a (tri)alkylamine salt, most preferably a TEAH+ salt.
• Step vii) triturating the deprotected cGMP analogue
• the method according to the invention comprises the step viii): vii) triturating the deprotected cGMP analogue.
• a deprotected cGMP analogue is as described above.
• This trituration is preferably to remove fluoride from a cGMP analogue fluoride complex.
• the inventors also surprisingly found that the trituration revealed an improved diastereomeric excess of isolated compounds of general formula (lll-Rp), and accordingly the invention provides a method for the production of a cGMP analogue, comprising step vi), more preferably comprising steps vi) and vii), wherein features and definitions are as defined elsewhere herein; preferably this method also comprises step viii) as described below.
• the deprotected cGMP analogue can be resuspended in a polar solvent, preferably in an aprotic polar solvent such as acetonitrile. It is then preferably filtered and washed, more preferably washed using the solvent in which it was resuspended.
• the resulting cGMP analogue preferably has a purity of at least 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or more percent. More preferably purity is at least 75%, even more preferably at least 80%, more preferably still at least 85%, even more preferably still at least 90%, still more preferably at least about 95%.
• This deprotected cGMP analogue is preferably substantially free of fluoride, more preferably entirely free of fluoride. Absence of fluoride can be confirmed using 19 F NMR. Purity can be assayed using known techniques, preferably it is assayed using HPLC. This compound is preferably a salt, more preferably a (tri)alkylamine salt, most preferably a TEAH+ salt.
• the cGMP analogue is either a free base or a pharmaceutically acceptable salt, more preferably a pharmaceutically acceptable salt.
• preferred methods according to the invention comprise a step viii): viii) converting the deprotected cGMP analogue to a pharmaceutically acceptable salt, preferably a sodium salt.
• a cGMP analogue converted in step viii) is preferably a product of step vi) or of step vii), most preferably of step vi) followed by step vii).
• This compound is most preferably a salt, more preferably a (tri)alkylamine salt, most preferably a TEAH+ salt.
• the cGMP analogue is admixed with a protic solvent, more preferably a lower alcohol such as methanol. This preferably results in a suspension.
• a protic solvent more preferably a lower alcohol such as methanol.
• an alkoxide salt of which the counterion is the intended counterion for the pharmaceutically acceptable cGMP salt preferably an alkoxide salt of the solvent and an alkali metal such as potassium or sodium, more preferably sodium.
• a preferred alkoxide salt is sodium methoxide.
• the resulting solution is preferably concentrated in vacuo to obtain a pharmaceutically acceptable salt of the cGMP analogue, preferably the sodium salt.
• the resulting solids are preferably stirred with a lower alcohol, more preferably with ethanol, after which solids are separated by filtration.
• a lower alcohol more preferably with ethanol
• the invention provides a method for the production of a cGMP analogue, comprising step viii) wherein features and definitions are as defined elsewhere herein; preferably this method also comprises step vii) as described above.
• the solids are stirred with a slightly wet lower alcohol, more preferably with a slightly wet ethanol, most preferably with 96% ethanol (wherein the remaining 4%, both being vol.-%, is preferably substantially water), for at least 1 , more preferably at least 2 hours.
• the filtrate is preferably concentrated in vacuo. Purity of the resulting solids is preferably further increased by further suspension in dry lower alcohol, preferably in dry ethanol, after which the suspension is filtered and the solids are preferably washed with additional dry alcohol, preferably the same alcohol used for resuspension. Afterwards the obtained solids are preferably dried, such as vacuum dried.
• the pharmaceutically acceptable salt of a cGMP analogue comprises at most 10% of the undesired diastereomer, more preferably at most 5%, even more preferably at most 4, 3, or 2%, even more preferably at most 1 % such as at most 0.5%.
• the pharmaceutically acceptable salt of a cGMP analogue has a purity of at least 80, 85, 90, 91 , 92, 93, 94, 95, 96, 97, 98, 99, or more percent. More preferably purity is at least 90%, even more preferably at least 94%, more preferably still at least 95%, even more preferably still at least 96%, still more preferably at least about 97%. Purity can be assayed using known techniques, preferably using NMR.
• the method according to the invention wherein X 2 is p' the method further comprising the steps of: vi) deprotecting the hydroxyl moiety that is protected by X2 to obtain a deprotected cGMP analogue; and vii) optionally triturating the deprotected cGMP analogue; and viii) optionally converting the deprotected cGMP analogue to a pharmaceutically acceptable salt, preferably a sodium salt.
• the invention provides several of these compounds, preferably a compound of general formula (II) or a salt thereof, wherein h, X 1 , X 2 , R 1 , and R 2 are as defined above; wherein o 1 and o 3 are each independently -OH or as defined for compounds of general formula (P), wherein preferably o 3 is H or o 1 and o 3 together form a chiral auxiliary that is preferably a C2-i2hydrocarbon; wherein M is S or O; wherein preferably the compound is a salt.
• the products can be used in the manufacture of a medicament, preferably a medicament for the treatment of retinitis pigmentosa.
• o 3 is H and o 1 is - OH, -O-Ci-shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, borano, methylborano, dimethylborano, cyanoborano, or -N(Ci-shydrocarbon)2, more preferably -O-Ci-shydrocarbon, -S- Ci-shydrocarbon, -NH-Ci-shydrocarbon, or -N(Ci-shydrocarbon)2.
• o 1 and o 3 are both -OH, -O-Ci-shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, borano, methylborano, dimethylborano, cyanoborano, or -N(Ci-shydrocarbon)2, more preferably -O-Ci- shydrocarbon, -S-Ci-shydrocarbon, -NH-Ci-shydrocarbon, or -N(Ci-shydrocarbon)2.
• o 1 and o 3 together form a chiral auxiliary as defined above. Most preferably, o 1 is -OH and o 3 is H.
• the compounds within this aspect are crystalline.
• the intermediate can also be a hydrate or a solvate.
• the crystal is a solvate, more preferably an isopropyl acetate solvate.
• the crystal is a hydrate.
• the crystal is not a solvate or a hydrate.
• the crystal comprises fluoride.
• the crystal comprises substantially pure intermediate, more preferably having a purity of at least 80, 85, 90, 91 , 92, 93, 94, 95, 96, 97, 98, 99, or 100%, even more preferably of at least 95, 96, 97, 98, 99, or 100%, most preferably of at least 97% or optionally more.
• the invention provides a compound of general formula (II) or a salt thereof, wherein h, X 1 , X 2 , R 1 , and R 2 are as defined above; wherein o 1 is -OH or as defined for compounds of general formula (P), wherein o 3 is H; wherein M is S or O; wherein preferably the compound is a salt, more preferably a TEAH+ salt. Further features and definitions are as described in the first aspect above for compounds of general formula (II).
• the invention provides a compound of general formula (II) or a salt thereof, wherein h, X 1 , X 2 , R 1 , and R 2 are as defined above; wherein or o 1 and o 3 together form a chiral auxiliary that is preferably a C2-i2hydrocarbon; wherein M is S or O; wherein preferably the compound is a salt. Further features and definitions are as described in the first aspect above for compounds of general formula (II).
• the word “about” or “approximately” when used in association with a numerical value preferably means that the value may be the given value more or less 1 % of the value.
• An oxoacid is also known as an oxyacid and is a compound that contains hydrogen, oxygen, and at least one atom of a further element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H + cation and the anion of the acid.
• a phosphorous oxoacid is an oxoacid wherein the further element is phosphorous.
• Alkyl groups have the general formula C n H2n+i and may alternately be linear or branched.
• Unsubstituted alkyl groups may also contain a cyclic moiety, and thus have the concomitant general formula C n H2n-i.
• the alkyl groups are substituted by one or more substituents further specified in this document. Examples of alkyl groups include methyl, ethyl, propyl, 2-propyl, t-butyl, 1 -hexyl, 1 -dodecyl, etc.
• -H may optionally be substituted with one or more substituents independently selected from the group consisting of Ci - C12 alkyl groups, C2- C12 alkenyl groups, C2 - C12 alkynyl groups, C3 - C12 cycloalkyl groups, C5 - C12 cycloalkenyl groups, Cs - C12 cycloalkynyl groups, Ci - C12 alkoxy groups, C2 - C12 alkenyloxy groups, C2 - C12 alkynyloxy groups, C3 - C12 cycloalkyloxy groups, halogens, amino groups, oxo and silyl groups, wherein the silyl groups can be represented by the formula (R s )3Si-, wherein R s is independently selected from the group consisting of Ci - C12 alkyl groups, C2 - C12 alkenyl groups, C2 - C12 alkynyl groups, C3 - C
• Physiological conditions are known to a person skilled in the art, and generally comprise aqueous solvent systems, atmospheric pressure, pH-values between 6 and 8, a temperature ranging from room temperature to about 37° C (from about 20° C to about 40° C), and a suitable concentration of buffer salts or other components. It is understood that charge is often associated with equilibrium.
• a moiety that is said to carry or bear a charge is a moiety that will be found in a state where it bears or carries such a charge more often than that it does not bear or carry such a charge.
• an atom that is indicated in this disclosure to be charged could be non-charged under specific conditions, and a neutral moiety could be charged under specific conditions, as is understood by a person skilled in the art.
• a decrease or increase of a parameter to be assessed means a change of at least 5% of the value corresponding to that parameter. More preferably, a decrease or increase of the value means a change of at least 10%, even more preferably at least 20%, at least 30%, at least 40%, at least 50%, at least 70%, at least 90%, or 100%. In this latter case, it can be the case that there is no longer a detectable value associated with the parameter.
• Filtration can be performed using any method known in the art, such as preferably using a Buchner funnel or an agitated Nutsche filter.
• Fig. 1 synthetic route towards Rp-8-Br-PET-cGMPS.
• Cyclic guanosinemonophosphorothioate analogue 1a is currently showing potential as a drug for the treatment of inherited retinal neurodegenerations.
• a diastereoselective and chromatography-free synthesis for its preparation. Notable features in the synthetic sequence include a silylation step with 80% selectivity for the 2’, 5’- over the 3’,5’-hydroxyls and a ring-closure of a 5’-/7-phosphonate monoester with 90% selectivity for the Sp-diastereomer.
• Compounds were isolated via crystallization, including the final product 1a which was obtained as a EtsNI salt in 125 g yield and >99.9% HPLC purity.
• cGMPS cyclic guanosinemonophosphorothioate
• 1a cyclic guanosinemonophosphorothioate
• the compound is an 8-bromo-cGMPS derivative with a phenylethenyl (PET) group on the nucleobase and an Reconfiguration on the thiophosphate.
• Cyclic nucleotidemonophosphorothioates cNMPSs
• cNMPSs Cyclic nucleotidemonophosphorothioates
• Sp- diastereomer 1b and their phosphate equivalent 1c were both found to be PKG agonists similarly to natural cGMP (Scheme 1).
• the desired isomer is treated with a strong base and carbon disulfide (Stec reaction) to yield the cyclic thiophosphate with complete retention of configuration.
• Eckstein and coworkers used bisnitrophenylphosphorochloridothioate on unprotected nucleosides to prepare 5’- bisnitrophenylphosphorothioates. These were directly cyclized by treatment with potassium tert-butoxide.
• Genieser’s group used a similar approach by employing thiophosphorylchloride to obtain 5’-thiophosphorodichloridates as precursors for the cyclization step, and were in fact the first group to synthetize 1a as described in US5625056.
• Diphenyl phosphite (DPP, diphenyl /7-phosphonate) is a common reagent for the formation of nucleoside / -phosphonate monoesters. It readily undergoes transesterification with alcohols and nucleosides in pyridine forming mixed phenyl /7-phosphonate diesters (e.g. diester 7, scheme 3). After hydrolysis of the phenyl moiety, a nucleoside monoester is obtained in good yield. When DPP (1 equiv.
• the final sulfurized mixture contained 75-80% of the desired product (according to 31 P-NMR), the remainder being the undesired diastereomer and small amounts of impurities in the phosphite area (>110 ppm) and product area ( ⁇ 50 ppm), as well as some small amounts of starting material.
• Another commonly used coupling agent diphenylchlorophosphate (DPCP) was also tried but it gave the same diastereomer ratios and offered no benefits. Large excess of coupling agent should be avoided as some side products became more pronounced, particularly with DPCP. Using 1.3 equiv. of Pv-CI was found to be sufficient for full conversion as well as giving a reaction tolerant to adventitious water.
• 8-Bromo-p-phenyl-1 ,N2-ethenoguanosine (2) 8-Bromoguanosine (683 g, 1.86 mol) was dissolved in DMSO (3.41 L, 5 vol.) and DBU (706 g, 2.5 eq., 4.64 mol). 2-Bromoacetophenone (443 g, 1 .5 eq., 2.23 mol) was charged dropwise over 30 minutes to the reaction mixture which was kept at around 25 °C. The reaction was stirred for 1 h before addition of cone, acetic acid (334 g, 3 eq., 5.57 mol).
• T riethylammonium Rp-8-Bromo-p-phenyl-1 ,N2-ethenoguanosine-3’,5’-cyclic monophosphorothioate (1a).
• Triethylamine trishydrofluoride (620 mL, 2 vol.) was charged to a solution of the crude phosphorothiotic acid 6 in THF (1.24 L, 4 vol.). The mixture was seeded and stirred which caused a precipitate to form over three nights.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Biochemistry (AREA)
• Biotechnology (AREA)
• General Health & Medical Sciences (AREA)
• Genetics & Genomics (AREA)
• Molecular Biology (AREA)
• Saccharide Compounds (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=77640578

Family Applications (1)

Country Status (5)

Cited By (1)

Citations (7)

• 2022
  • 2022-09-06 CN CN202280060253.0A patent/CN117999269A/zh active Pending
  • 2022-09-06 WO PCT/EP2022/074740 patent/WO2023031481A1/en not_active Ceased
  • 2022-09-06 JP JP2024513779A patent/JP2024530774A/ja active Pending
  • 2022-09-06 US US18/687,856 patent/US20240352056A1/en active Pending
  • 2022-09-06 EP EP22773633.7A patent/EP4399215A1/en active Pending

Patent Citations (7)

Non-Patent Citations (29)

Also Published As

Similar Documents

Legal Events