Processes for the preparation of inhibitory compounds

Abstract

The present invention relates to processes for the preparation of a compound that functions as an inhibitor of METTL3 (N6-adenosine-methyltransferase 70 kDa subunit) activity, and their synthetic intermediates.

Description

PROCESSES FOR THE PREPARATION OF INHIBITORY COMPOUNDSFIELD OF THE INVENTION

[0001] The present invention relates to a novel process for the preparation of an inhibitor of METTL3 (N6-adenosine-methyltransferase 70 kDa subunit) activity, and their synthetic intermediates.BACKGROUND OF THE INVENTION

[0002] A / 6-methyladenosine (m6A) is the most common and abundant covalent modification of messenger RNA, modulated by ‘writers’, ‘erasers’ and ‘readers’ of this mark (Meyer & Jaffrey 2014, Niu Y et al, 2013, Yue et al 2015). Approximately 0.1 to 0.5% of all mRNA adenosines are m6A modified (Li Y et al 2015). In vitro data have shown that m6A influences fundamental aspects of mRNA biology, mainly mRNA expression, splicing, stability, localisation and translation (Meyer et al, 2015; Sledz & Jinek 2016). M6A modifications are tissue specific and there is significant variability in their occurrence profiles in non-diseased tissues (e.g. brain, heart, kidney) and diseased tissues and cells (lung, renal, breast, and leukeamic cancer cells) (Meyer et al 2012).

[0003] The m6A modifications and its erasers and writers such as FTO, ALKBH5, methyltransferese like 3 (METTL3) and METTL14 are associated with major diseases such as solid organ cancers, leukaemia, type 2 diabetes, neuropsychiatric behavioural and depressive disorders (Chandola et al 2015; Koranda et al 2018).

[0004] The RNA methyltransferase, METTL3, is the major, but not the sole enzyme, that catalyses m6A modification of RNA. It exists as a hetero-trimeric complex with METTL14 (Liu et al 2014, Wang et al 2016) and Wilm’s Tumour Associated Protein (WTAP) (Ping et al 2014). Catalytic activity resides in METTL3, which transfers a methyl group from the co-factor S- adenosyl methionine to the substrate RNA and METTL14 facilitates substrate RNA binding. WTAP localises the complex in specific nuclear regions and also localises RNA substrates to the complex (Wang X et al 2016).

[0005] METTL3 has been reported to play a role in many aspects of the development of cancer (Fry et al 2018). Genetic knockdown of METTL3 in lung cancer cell lines (A549, H1299 and H1792) and HeLa cells leads to decreased growth, survival and invasion of human lung cancer cells (Lin S et al 2016). METTL3 is significantly up-regulated in human bladder cancer (Cheng et al 2019). Knockdown of METTL3 drastically reduced bladder cancer cell proliferation, invasion, and survival in vitro and tumorigenicity in vivo. AF4 / FMR2 family member 4 (AFF4), two key regulators of NF-KB pathway (IKBKB and RELA) and MYC were further identified as direct targets of METTL3-mediated m6A modification. In renal carcinomacell lines (CAK-1 , CAK-2 and ACHN), genetic knockdown reduced cell proliferation via the phosphatidinylinositol 3-kinase (PI3K) / AKT / mammalian target of rapamycin (mTOR) signalling pathway (Li X et al 2017).

[0006] Recently Barbieri et al (2017), defined a set of RNA-modifying enzymes that are necessary for AML leukaemia and identified a key leukaemic pathway for the METTL3 RNA methyltransferase. In this pathway, METTL3 is stably recruited by the CCAAT-box binding transcription factor CEBPZ to promoters of a specific set of active genes, resulting in m6A methylation of the respective mRNAs and increased translation. One important target is SP1, an oncogene in several cancers, which regulates c-MYC expression. Consistent with these findings, it has been reported that METTL3 can methylate its targets co-transcriptionally.

[0007] The pathway described by Barbieri et al., is critical for A L leukaemia, as three of its components are required for AML cell growth: (i) the m6A RNA methyltransferase METTL3; (ii) the transcription factor CEBPZ, which targets this enzyme to promoters; and (iii) SP1 , whose translation is dependent upon the m6A modification by METTL3. Together, the observations of Barbieri et al define METTL3 enzymatic activity as a new candidate target for the treatment of AML.

[0008] In separate, independent studies it has been reported that METTL3 plays an essential role in controlling myeloid differentiation of mammalian normal hematopoietic and leukemic cells (Vu et al 2017). Forced expression of wild type METTL3, but not a mutant METTL3 (with defect in catalytic activity), significantly promotes cell proliferation and inhibits cell differentiation of human cord blood-derived CD34+ haematopoietic stem / progenitor cells (HSPCs). Genetic knockdown of METTL3 has the opposite effects. METTL3 is highly expressed in AML compared to normal HSPCs or other types of cancers. Knockdown of METTL3 in human AML cell lines significantly induces cell differentiation and apoptosis and inhibits leukemia progression in mice xeno-transplanted with MOLM-13 AML cells. The biological function of METTL3 is likely attributed to the promotion of translation of its mRNA targets such as MYC, BCL-2, and PTEN in an m6A-dependent manner.

[0009] Recently, METTL3 mediated m6A modification has been demonstrated to play an important role in T cell homeostasis and signal dependent induction of mRNA degradation in CD4 positive T cell lineages (Li et al 2017). Deletion of METTL3 in mouse T cells disrupts T cell homeostasis and differentiation. In a lymphopenic mouse adoptive transfer model, naive Meff / 3-deficient T cells failed to undergo homeostatic expansion and remained in the naive state for up to 12 weeks, thereby preventing colitis. Consistent with these observations, the mRNAs of SOCS family genes encoding the STAT signalling inhibitory proteins SOCS1 , SOCS3 and CISH were marked by m6A, exhibited slower mRNA decay and showed increased mRNAs and levels of protein expression in / Wetf / 3-deficient naive T cells. This increased SOCS family activity consequently inhibited IL-7-mediated STAT5 activation and T cell homeostaticproliferation and differentiation. Thus METTL3 mediated m6A methylation has important roles for inducible degradation of Socs mRNAs in response to IL-7 signalling in order to reprogram naive T cells for proliferation and differentiation, pointing to a role in auto-immunity.

[0010] Recent studies have revealed that depletion of METTL3 leads to alterations in the propagation of diverse viruses (Winkler et al). Foil owing viral infection or stimulation of cells with an inactivated virus, deletion of the m6A ‘writer’ METTL3 led to an increase in the induction of interferon-stimulated genes. Consequently, propagation of different viruses was suppressed in an interferon-signalling-dependent manner. Significantly, the mRNA of IFNB, was m6A modified and was stabilized following repression of METTL3. m6A serves as a negative regulator of interferon response by dictating the fast turnover of interferon mRNAs and consequently facilitating viral propagation. Therefore, METTL3 inhibitors may provide a novel therapeutic approach to a range of infectious and inflammatory diseases.

[0011] Inhibitors of METTL3 are described in International Patent Publication Numbers W02020 / 050898, WO2021 / 111124 and WO2022 / 074379. A process for making certain METTL3 inhibitors is described in International Patent Publication Number WO2022 / 254218.

[0012] Improved processes for the manufacture of certain METTL3 inhibitors of interest are required. The present invention was devised with the foregoing in mind.

[0013] An object of this invention is therefore to provide an improved process for preparing certain METTL3 inhibitors.ReferencesBarbieri I, Tzelepis K, Pandolfini L, Shi J, Millan-Zambrano G, Robson SC, Aspris D, Migliori V, Bannister AJ, Han N, De Braekeleer E, Ponstingl H, Hendrick A, Vakoc CR, Vassiliou GS, Kouzarides T. Nature. 2017 Dec 7;552(7683): 126-131.Chandola U, Das R, Panda B. Brief Funct Genomics. 2015 May;14(3):169-79.Cheng M, Gao Q, Wu M, Liang Y, Zhu F, Zhang Y, Zhang X, Li Y, Sheng L, Zhang H, Xiong Q, Yuan Q, Oncogene (2019; e-publication ahead of print).Fry NJ, Law BA, llkayeva OR, Carraway KR, Holley CL, Mansfield KD. Oncotarget. 2018 Jul 27;9(58):31231-31243.Koranda JL, Dore L, Shi H, Patel MJ, Vaasjo LO, Rao MN, Chen K, Lu Z, Yi Y, Chi W, He C, Zhuang X. Neuron. 2018 July 25; 99(2): 283-292.Li HB, Tong J, Zhu S, Batista PJ, Duffy EE, Zhao J, Bailis W, Cao G, Kroehling L, Chen Y, Wang G, Broughton JP, Chen YG, Kluger Y, Simon MD, Chang HY, Yin Z, Flavell RA. Nature. 2017 Aug 17;548 (7667): 338-342Li X, Tang J, Huang W, Wang F, Li P, Qin C, Qin Z, Zou Q, Wei J, Hua L, Yang H, Wang Z. Oncotarget. 2017 Oct 10;8(56):96103-96116.Li Y, Wang Y, Zhang Z, Zamudio AV, Zhao JC. RNA. 2015 Aug;21(8):1511-8.Lin S, Choe J, Du P, Triboulet R, Gregory Rl. Mol Cell. 2016 May 5;62(3):335-345.Liu J, Yue Y, Han D, Wang X, Fu Y, Zhang L, Jia G, Yu M, Lu Z, Deng X, Dai Q, Chen W, He C. Nat Chem Biol. 2014 Feb;10(2):93-5.Meyer KD, Patil DP, Zhou J, Zinoviev A, Skabkin MA, Elemento O, Pestova TA, Qian SB, Jaffrey SR. Cell. 2015 Nov 5; 163(4): 999-1010.Meyer KD, Jaffrey SR. Nat Rev Mol Cell Biol. 2014 May; 15(5) :313-26.Meyer KD, Saletore Y, Zumbo P, Elemento O, Mason CE, Jaffrey SR. Cell. 2012 Jun 22; 149(7): 1635-46.Niu Y, Zhao X, Wu YS, Li MM, Wang XJ, Yang YG. Genomics Proteomics Bioinformatics. 2013 Feb;11(1):8-17.Ping XL, Sun BF, Wang L, Xiao W, Yang X, Wang WJ, Adhikari S, Shi Y, Lv Y, Chen YS, Zhao X, Li A, Yang Y, Dahal U, Lou XM, Liu X, Huang J, Yuan WP, Zhu XF, Cheng T, Zhao YL, Wang X, Rendtlew Danielsen JM, Liu F, Yang YG. Cell Res. 2014 Feb;24(2):177-89.Sledz P, Jinek M. Elife. 2016 Sep 14;5.Vu LP, Pickering BF, Cheng Y, Zaccara S, Nguyen D, Minuesa G, Chou T, Chow A, Saletore Y, MacKay M, Schulman J, Famulare C, Patel M, Klimek VM, Garrett-Bakelman FE, Melnick A, Carroll M, Mason CE, Jaffrey SR, Kharas MG. Nat Med. 2017 Nov;23(11):1369-1376.Wang X, Feng J, Xue Y, Guan Z, Zhang D, Liu Z, Gong Z, Wang Q, Huang J, Tang C, Zou T, Yin P. Nature. 2016 Jun 23;534(7608):575-8Wang P, Doxtader KA, Nam Y. Mol Cell. 2016 Jul 21 ;63(2):306-317.Winkler R, Gillis E, Lasman L, Safra M, Geula S, Soyris C, Nachshon A, Tai-Schmiedel J, Friedman N, Le-Trilling Vu T K, Trilling M, Mandelboim M, Hanna, J H, Schwartz S, Stern- Ginossar N. Nature Immunology (2018, e-publication ahead of print).Yue Y, Liu J, He C. Genes Dev. 2015 Jul 1 ;29( 13): 1343-55SUMMARY OF THE INVENTION

[0014] In general, the present invention provides an improved method for the synthesis of a compound of structural formula I shown below, which is a potent inhibitor of METTL3.N-[(2-{[(cyclobutylmethyl)amino]methyl}-1H-indol-6-yl)methyl]-4-oxo-4H-pyrido[1,2- a]pyrimidine-2-carboxamide

[0015] The process includes a number of steps, as outlined further below:Process for preparing Intermediate-1 C

[0016] lntermdiate-1C is a known compound and can be prepared by techniques known in the art. In a particular embodiment and aspect of the present invention, there is provided a process for preparing Intermediate-1 C having the structural formula INT-1C shown below:the process comprising the steps:(a-i) reacting a compound of the formula A1 shown below:with a compound of the formula A2:wherein Ri and R2are each independently selected from (1-4C)alkyl, and preferably Ri and R2are methyl or ethyl (more preferably Ri and R2are ethyl);to form a compound of the formula A3:(A3); and(a-ii) reducing the nitro group present in the compound of formula A3 formed in step (a-i) above and cyclising the compound to form a compound of formula SM-1:(SM-1)(a-iii) hydrolysing ester group of the compound of the formula SM-1 formed in step (a-ii) to form lntermediate-1C.

[0017] Suitably, Ri and R2 are methyl or ethyl. More suitably, R1 and R2 are ethyl.

[0018] Compound A3 may exist as a mixture of keto and enol tautomers.Process for preparing Intermediate-1 A

[0019] According to one aspect of the present invention, there is provided a process for preparing lntermediate-1A having the structural formula (I NT-1 A) shown below:(INT-1A) the process comprising the steps:(c-i) reacting Intermediate-1 C having the structural formula INT-1C shown below:with Intermediate SM-2 having the structural formula SM-2 shown below:Process for preparing Intermediate-1 B

[0020] According to another aspect of the present invention, there is provided a process for preparing lntermediate-1B having the structural formula INT-1 B shown below:(INT-1B) the process comprising the step:(d-i) reducing lntermediate-1A having the structural formula INT-1A shown below:(INT-1A) with a reducing agent to form Intermediate 1 B.Process for preparing a compound of Formula I

[0021] According to another aspect of the present invention, there is provided a process for preparing a compound of the formula I defined herein, or a pharmaceutically acceptable salt thereof, the process comprising the steps:(i-i) reacting Intermediate-1 B having the structural formula INT-1 B shown below:(INT-1B) with Intermediate 5 having the structural formula INT-5 shown below:and(i-ii) optionally forming a pharmaceutically acceptable salt of the compound of formula I formed in step (i-i).

[0022] According to another aspect of the present invention, there is provided a process for preparing a compound of the formula I defined herein, or a pharmaceutically acceptable salt thereof, the process comprising the steps:(c-i) reacting lntermediate-1C (having the structural formula INT-1C shown above) with Intermediate SM-2 (having the structural formula SM-2 shown above) to form lntermediate-1A (having the structural formula INT-1A shown above);(d-i) reducing lntermdiate-1A formed in step (c-i) with a reducing agent to form lntermediate-1 B (having the structural formula INT-1B shown above);(i-i) reacting Intermediate-1 B formed in step (d-i) with Intermediate 5 (a compound of the formula INT-5 shown above) to form a compound of formula I as defined herein; and(i-ii) optionally forming a pharmaceutically acceptable salt of the compound of formula I.

[0023] According to another aspect of the present invention, there is provided a process for preparing a compound of the formula I defined herein, or a pharmaceutically acceptable salt thereof, the process comprising the steps:(c-i) reacting lntermediate-1C (having the structural formula INT-1C shown above) with Intermediate SM-2 (having the structural formula SM-2 shown above) to form lntermediate-1A (having the structural formula INT-1A shown above);(d-i) reducing lntermdiate-1A formed in step (c-i) with a reducing agent to form lntermediate-1 B (having the structural formula INT-1B shown above);(i-i) reacting Intermediate-1 B formed in step (d-i) with Intermediate 5 (a compound of the formula INT-5 shown above) to form a compound of formula I as defined herein; and(i-ii) optionally forming a pharmaceutically acceptable salt of the compound of formula I. wherein: lntermdiate-1C is optionally prepared by a process comprising the steps:(a-i) reacting a compound of the formula A1 defined above with a compound of the formula A2 defined above to form a compound of the formula A3 defined above;(a-ii) reducing the nitro group present in the compound of formula A3 formed in step (a-i) above and cyclising the compound to form a compound of formula SM- 1 ; and(a-iii) hydrolysing the ester group of the compound of the formula SM-1 formed in step (b) to form lntermediate-1C; and / orIntermediate 5 is optionally prepared by a process comprising the step:(e-i) reacting a compound of the formula E1 defined above with a compound of the formula E2 defined above to form Intermediate-5.

[0024] In a further aspect, the present invention provides a compound of formula (I) as defined herein, wherein the compound is obtainable by, obtained by or directly obtained by any one of the processes for forming a compound of formula I defined herein.DETAILED DESCRIPTION OF THE INVENTIONDefinitions

[0025] Unless otherwise stated, the following terms used in the specification and claims have the following meanings set out below.

[0026] In this specification the term “alkyl” includes both straight and branched chain alkyl groups. References to individual alkyl groups such as “propyl” are specific for the straight chain version only and references to individual branched chain alkyl groups such as “isopropyl” are specific for the branched chain version only. For example, (1-4C)alkyl includes (1-3C)alkyl, methyl, ethyl, propyl and isopropyl.

[0027] The term "(m-nC)" or “Cm-n”, or "(m-nC) group" or “Cm-n” used alone or as a prefix, refers to any group having m to n carbon atoms.

[0028] It is to be understood that certain compounds and intermediates disclosed herein may exist in salt forms. A suitable pharmaceutically acceptable salt of a compound of Formula I is, for example, an acid-addition salt. For example, an acid addition salt with an inorganic or organic acid. Particular examples of suitable salts include hydrochloride, hydrobromide, sulphate, phosphate, acetate, trifluoroacetate, formate, fumarate, citrate, methane sulfonate, oxalate, tartate, malate, maleate, p-toluenesulfonate, benzene sulfonate, succinate, hemisuccinate or benzoate salts.

[0029] It is also to be understood that certain compounds disclosed herein may exist in solvated as well as unsolvated forms such as, for example, hydrated forms.

[0030] It is also to be understood that certain compounds disclosed herein may exist in different tautomeric forms, even though only one possible tautomeric form is depicted by the structure shown. For the avoidance of doubt, where a compound can exist in one of several tautomeric forms, and only one is specifically described or shown, all others are nevertheless embraced by formula depicted. Examples of tautomeric forms include keto-, enol- tautomers.Processes of the invention

[0031] The process of the present invention was designed to provide an improved process for the preparation of the compound of formula I defined herein. In particular, relative to prior art methods, the process provides a cost-effective synthesis (using commercially available raw materials) as well as improved yields, improved purity in the final product and a reduced number of synthetic steps.Process for preparing Intermediate SM-1

[0032] Intermediate SM-1 may be sourced commercially or prepared by any suitable process known in the art.

[0033] In a particular embodiment and aspect of the present invention, there is provided a process for preparing Intermediate SM-1 having the structural formula SM-1 shown below:wherein Ri is (1 -3C)alkyl, and preferably is methyl or ethyl, more preferably ethyl); the process comprising the steps:(a-i) reacting a compound of the formula A1 shown below:with a compound of the formula A2:wherein Ri and R2 are each independently selected from (1-4C)alkyl , and preferably Ri and R2 are methyl or ethyl; to form a compound of the formula A3:(A3); and(a-ii) reducing the nitro group present in the compound of formula A3 formed in step (a-i) above and then cyclising the compound to form a compound of formula SM-1.

[0034] Suitably, Ri and R2are methyl or ethyl. More suitably, Ri and R2are ethyl.

[0035] The synthesis of the compound SM-1 is described in, for example, J. Med. Chem. 1997, 40, 2843-2857. As such, suitable reaction conditions and solvents for steps (a-1) and (a-ii) are known in the art.Process for preparing Intermediate-5

[0036] Intermediate 5 may be prepared by processes known in the art. Suitable processes for preparing Intermediate 5 can be found in, for example, International Patent Publication Number WO2022 / 254218.

[0037] In a particular embodiment and aspect of the present invention, Intermediate 5 having the structural formula I NT-5 shown below:is prepared by a process comprising the step:(e-i) reacting a compound of the formula E1 shown below:with a compound of the formula E2:to form Intermediate 5.

[0038] Suitable reaction conditions and solvents and procedures for preparing Intermediate 5 are known in the art and described in, for example, International Patent Publication Number

[0039] An overview of the process for preparing a compound of formula I according to the present invention (also referred to as Cpd 1) is shown below:INT-5

[0040] Suitably, Ri in the scheme above is selected from methyl or ethyl. More suitably, Ri is ethyl.

[0041] The synthesis / sourcing of the known starting materials SM-1 and INT-5 are discussed above.

[0042] Each stage of the process outlined above is discussed in more detail below, and is exemplified in the accompanying example section.Process for preparing Intermediate-1 C

[0043] lntermdiate-1C is a known compound and can be prepared by techniques known in the art (e.g. Journal of the Chemical Society, Transactions (1924), 125, 2285-91 or J. Med. Chem. 1997, 40, 2843-2857).

[0044] In a particular embodiment and aspect of the present invention, Intermediate-1 C having the structural formula INT-1C shown below:(INT-1C) is prepared by a process comprising the step:(a-iii) hydrolysing ester group of the compound of the formula SM-1 (formed in step (a-ii) above)(SM-1) wherein Ri is (1-3C)alkyl; to form lntermediate-1C.

[0045] Suitably, R3is methyl or ethyl. More suitably, R3is ethyl.

[0046] Suitably the compound SM-1 is methyl 6-cyano-1 H-indole-2-carboxylate or ethyl 6- cyano-1H-indole-2-carboxylate. More suitably, SM-1 is ethyl 6-cyano-1 H-indole-2- carboxylate.

[0047] The synthesis of lntermediate-1C is described in, for example, Journal of the Chemical Society, Transactions (1924), 125, 2285-91 or J. Med. Chem. 1997, 40, 2843-2857. As such, suitable reaction conditions and solvents for step (a-iii) are known in the art.

[0048] In step (a-iii) of the process, the ester group of the compound SM-1 formed in step (a- ii) above is hydrolysed to form Intermediate-1 C. Any suitable ester hydrolysis conditions may be used in this step along with any suitable solvent.

[0049] In an embodiment of the process, the hydrolysis reaction in step (a-iii) above is conducted in alkaline conditions, e.g. in the presence a suitable aqueous metal hydroxide, e.g. aqueous sodium hydroxide.

[0050] In a particular embodiment of the process, a solution of a compound according to formula (SM-1) (e.g. ethyl 6-cyano-1H-indole-2-carboxylate) in a suitable water miscible solvent, e.g. a polar aprotic solvent, such as tetrahydrofuran (THF), is mixed with an aqueous solution of a metal hydroxide, e.g. sodium hydroxide, and the reaction is allowed to proceed. Suitably, the reaction proceeds at ambient temperature, e.g. 0-25°C or 5-25°C or 20°C, optionally for a period of 30 minutes to 10 hours, or 30 minutes to 6 hours, or 1 to 5 hours, or 2 to 4 hours. The reaction mixture may then be acidified.

[0051] In a particular embodiment of the process, a solution of a compound according to formula (SM-1) (e.g. ethyl 6-cyano-1H-indole-2-carboxylate) in a suitable water immiscible solvent, e.g. a polar aprotic solvent, such as 2-methyl tetrahydrofuran (2-MeTHF), is mixed with an aqueous solution of a metal hydroxide, e.g. sodium hydroxide, and the reaction is allowed to proceed. Suitably, the reaction proceeds at ambient or elevated temperature, e.g. 0-75°C or 25-50°C or 25°C, optionally for a period of 30 minutes to 12hours, or 30 minutes to 8 hours, or 1 to 6 hours, or 2 to 4 hours. The reaction mixture may then be acidified.

[0052] Intermediate-1 C is collected (precipitated and washed) and optionally purified using standard techniques known in the art (e.g. as described in the Example 1 of the example section herein).Process for preparing Intermediate-1 A

[0053] The present invention provides a process for preparing lntermediate-1A having the structural formula (INT-1A) shown below:(INT-1A) the process comprising the steps:(c-i) reacting Intermediate-1 C having the structural formula INT-1C shown below:with Intermediate SM-2 having the structural formula SM-2 shown below:(SM-2).

[0054] A person skilled in the art will appreciate that suitable reactions conditions and solvents may be used for the amide coupling between INT-1C and SM-2 to form INT-1A.

[0055] Suitably, lntermediate-1C is activated by an initial reaction with a suitable activating agent prior to the reaction with Intermediate SM-2. Examples of suitable activating agents include thionyl chloride, pivaloyl chloride, isobutyl chloroformate, dicyclohexylcarbodiimide (DCC), diethyl chlorophosphate, carbonyl diimidazole (CDI) and A / -(Dimethylaminopropyl)-A / '- ethyl-carbodiimide (EDCI). In an embodiment, the activating agent is thionyl chloride or EDCI.

[0056] Suitably, Intermediate- 1C is dissolved in a suitable solvent (e.g. a dichloromethane), optionally with an additional co-solvent added (e.g. dimethylformamide) and reacted with an activating agent, e.g. thionyl chloride or EDCI. This reaction is mixture may be refluxed for 1 to 8 hours or 1 to 4 hours (e.g. for 2 hours). The temperature of the reaction will vary depending on the nature of the solvent system used and the activating agent. Suitably, the reaction temperature is 35-50 degrees Celsius, and most suitably 35-45 degrees Celsius. Suitably, the reaction is conducted in an inert atmosphere, e.g. under nitrogen. The product of this reaction is then dissolved in a suitable solvent (e.g. dichloromethane) and reacted with Intermediate SM-2.

[0057] Any suitable solvent may be used for the reaction step (c-i) above. In an embodiment of the process, the solvent is selected from dichloromethane, dichloroethane, chloroform, tetrahydrofuran, 2-methyltetrahydrofuran, ethyl acetate, dimethylformamide, dimethylsulfoxide, toluene or acetone, especially dichloromethane, tetrahydrofuran, 2- methyltetrahydrofuran or toluene. Most suitably, the solvent is dichloromethane or tetrahydrofuran, especially dichloromethane.

[0058] Suitably, the reaction step (c-i) between Intermediate-1 C and SM-2 takes place in the presence of a suitable base, e.g. triethylamine, diisopropyl ethylamine (DI PEA), DMAP or tributylamine.

[0059] lntermediate-1A formed by this reaction may be collected and optionally purified using standard techniques known in the art (e.g. as described in the Example 2 of the example Section herein).Process for preparing Intermediate-1 B

[0060] According to another aspect of the present invention, there is provided a process for preparing Intermediate-IB having the structural formula INT-1 B shown below:(INT-1B) the process comprising the step:(d-i) reacting lntermediate-1A having the structural formula INT-1A shown below:(INT-1A) with a reducing agent to form Intermediate 1 B.

[0061] Suitably, intermediate-1 A is reduced to form lntermediate-1B using a suitable reducing agent in an appropriate solvent.

[0062] Suitably, the reducing agent is lithium aluminium hydride. Suitably, the reaction is carried out in the presence of trimethylsilyl chloride.

[0063] Any suitable solvent may be used for the reaction. In an embodiment of the process, the solvent is selected from ethers, tetrahydrofuran, 2-methyltetrahydrofuran or toluene. Most suitably, the solvent is tetrahydrofuran or 2-methyltetrahydrofuran.

[0064] Optionally, the reaction is conducted in an inert atmosphere, e.g. under nitrogen.

[0065] Intermediate-1 B formed by this reaction may be collected and optionally purified using standard techniques known in the art (e.g. as described in Example 3 of the example section herein). One key aspect of the process of the invention will be to remove any residual aluminium residues. Any process to remove these residues may be used, for example, Rochelle’s salt (potassium sodium tartrate) may be used to form a complex with aluminium residues, or Intermediate 1 B may be crystalised, optionally in the form of a salt. Intermediate 1B may be crystallised in the free base form.Salts of the compound of Intermediate-1 B

[0066] As noted above, Intermediate-1 B may be optionally isolated in a salt form. Examples of suitable salts include acid addition salts such as hydrochloride, hydrobromide, sulphate, phosphate, acetate, trifluoroacetate, formate, citrate, methane sulfonate, oxalate, tartate, fumarate, malate, maleate, p-toluenesulfonate, methane sulfonate, benzene sulfonate, succinate, hemi-succinate or benzoate salts. Suitably, the salt form is hydrochloride, sulphate, or p-toluenesulfonate.Process for preparing a compound of Formula I

[0067] According to another aspect of the present invention, there is provided a process for preparing a compound of the formula I defined herein, or a pharmaceutically acceptable salt thereof, the process comprising the steps:(i-i) reacting Intermediate 1B having the structural formula I NT-1 B shown below:(INT-1B) with Intermediate 5 having the structural formula I NT-5 shown below:and(i-ii) optionally forming a pharmaceutically acceptable salt of the compound of formula I formed in step (i-i).

[0068] In an embodiment of the process, the compound of formula I is not in the form of a pharmaceutically acceptable salt, in which case, step (i-ii) above is absent.

[0069] Suitably, Intermediate-1 B and Intermediate-5 are reacted together in a suitable solvent and optionally in the presence of a suitable base, e.g. triethylamine, diisopropyl ethylamine (DIPEA) or tributylamine.

[0070] Any suitable solvent may be used for the reaction. In an embodiment of the process, lntermediate-1A is suspended in a polar solvent, e.g. methanol, ethanol, "propanol, isopropanol, DMF, THF, 2-MeTHF, acetonitrile or DMSO. Suitably, the polar solvent is methanol.

[0071] Suitably, the reaction is conducted in an inert atmosphere, e.g. under nitrogen.

[0072] Suitably, the reaction is conducted under reflux conditions for the solvent concerned for up to 20 hours and most suitably for 3 to 20 hours.

[0073] The compound of formula I formed by this reaction may be collected and purified using standard techniques known in the art (e.g. as described in the Example 4A and 4B of the example section herein).

[0074] According to another aspect of the present invention, there is provided a process for preparing a compound of the formula I defined herein, or a pharmaceutically acceptable salt thereof, the process comprising the steps:(a-iii) hydrolysing ester group of the compound of the formula SM-1 formed in step (a-ii) above to form Intermediate-1 C;(c-i) reacting lntermediate-1C (having the structural formula INT-1C shown above) with Intermediate SM-2 (having the structural formula SM-2 shown above) to form lntermediate-1A (having the structural formula INT-1A shown above);(d-i) reducing lntermdiate-1A formed in step (c-i) to form lntermediate-1 B (having the structural formula INT-1B shown above);(i-i) reacting Intermediate-1 B formed in step (d-i) with Intermediate 5 (a compound of the formula INT-5 shown above) to form a compound of formula I as defined herein; and(i-ii) optionally forming a pharmaceutically acceptable salt of the compound of formula I.

[0075] According to another aspect of the present invention, there is provided a process for preparing a compound of the formula I defined herein, or a pharmaceutically acceptable salt thereof, the process comprising the steps:(c-i) reacting lntermediate-1C (having the structural formula INT-1C shown above) with Intermediate SM-2 (having the structural formula SM-2 shown above) to form lntermediate-1A (having the structural formula INT-1A shown above);(d-i) reducing lntermdiate-1A formed in step (c-i) with a reducing agent to form lntermediate-1 B (having the structural formula INT-1 B shown above);(i-i) reacting Intermediate-1 B formed in step (d-i) with Intermediate 5 (a compound of the formula INT-5 shown above) to form a compound of formula I as defined herein; and(i-ii) optionally forming a pharmaceutically acceptable salt of the compound of formula I.

[0076] According to another aspect of the present invention, there is provided a process for preparing a compound of the formula I defined herein, or a pharmaceutically acceptable salt thereof, the process comprising the steps:(c-i) reacting lntermediate-1C (having the structural formula INT-1C shown above) with Intermediate SM-2 (having the structural formula SM-2 shown above) to form lntermediate-1A (having the structural formula INT-1A shown above);(d-i) reducing lntermdiate-1A formed in step (c-i) with a reducing agent to form lntermediate-1 B (having the structural formula INT-1B shown above);(i-i) reacting Intermediate-1 B formed in step (d-i) with Intermediate 5 (a compound of the formula INT-5 shown above) to form a compound of formula I as defined herein; and(i-ii) optionally forming a pharmaceutically acceptable salt of the compound of formula I. wherein: lntermdiate-1C is optionally prepared by a process comprising the steps:(a-i) reacting a compound of the formula A1 defined above with a compound of the formula A2 defined above to form a compound of the formula A3 defined above;(a-ii) reducing the nitro group present in the compound of formula A3 formed in step (a-i) above and cyclising the compound to form a compound of formula SM-1; and(a-iii) hydrolysing the ester group of the compound of the formula SM-1 formed in step (b) to form lntermediate-1C; and / orIntermediate 5 is optionally prepared by a process comprising the step:(e-i) reacting a compound of the formula E1 defined above with a compound of the formula E2 defined above to form Intermediate-5.

[0077] In a further aspect, the present invention provides a compound of formula (I) as defined herein, wherein the compound is obtainable by, obtained by or directly obtained by any one of the processes for forming a compound of formula I defined herein.

[0078] Suitably, the compound of Formula I is purified by techniques known in the art, for example by recrystallisation.Salts of the compound of formula I

[0079] Step (i-ii) of the processes defined above is optional. In an embodiment, the compound of formula I is provided as the free base. In an embodiment, the compound of formula I may be formed into a suitable salt, for example an acid addition salt, e.g. a hydrochloride, hydrobromide, sulphate, phosphate, acetate, trifluoroacetate, formate, citrate, methane sulfonate, oxalate, tartate, fumarate, malate, maleate, p-toluenesulfonate, methane sulfonate, benzene sulfonate, succinate, hemi-succinate or benzoate salts.

[0080] In another aspect, the present invention provides a pharmaceutically acceptable salt of a compound for formula I, suitably a hydrochloride, tosylate, benzenesulfonate, maleate, hemisuccinate or benzoate salt. In a further aspect, the present invention provides a maleate or hemisuccinate salt of a compound of formula I. In a particular aspect, the present invention provides a hemisuccinate salt of a compound of formula I.BRIEF DESCRIPTION OF THE FIGURESThe following figures are referred to in the Example Section below:Figure 1 shows the XRPD pattern of crystalline Form SUC1 of the hemisuccinate salt of the compound of formula I prepared in Example 5;Figure 2 shows the1H-NMR spectrum of the hemi-succinate salt of the compound of formula I prepared in Example 5;Figure 3 shows the TGA profile (blue line); DSC profile (green line) of crystalline Form SUC1 of the hemisuccinate salt of the compound of formula I prepared in Example 5;Figure 4 shows the MultiMax and FBRM combined plots relating to the crystallization of the compound of formula I in 1-PrOH / water described in Example 6;Figure 5 shows the XRPD diffractograms of the sample prepared in Example 6 (brown trace) and a reference Form 1 of the compound of formula I (red trace);Figure 6 shows the TGA trace for the sample prepared in Example 6;Figure 7 shows optical microscopy images of the crystals formed in Example 6.EXAMPLES

[0081] The example and preparations provided below further illustrate and exemplify the compounds of the present invention and methods of preparing such compounds. It is to be understood that the scope of the present invention is not limited in any way by the scope of the following examples.Analytical methodsHPLC MethodsMethod 1 :Method 2: POS-NEG-5-95CD_2.5min: LC / MS (The column used for chromatography was X Bridge C182.1*30mm, (5 urn particles). Detection methods are diode array (DAD). MS mode was positive and negative electrospray ionization. MS range was 50-2000. Mobile phase A was 10 mM Ammonium bicarbonate in water, and mobile phase B was HPLC grade acetonitrile. Using the elution gradient 5%- 95% (solvent B) over 1.5 min and holding at 95% B for 0.50 min at a flow rate of 1.2 mL / min (0.01-2.50 min).Method 4: 30-90_AB_20min: HPLC( The gradient was 30-90% B in 16.00 min ,90-100%B in 3. OOmin, 100-30% B in 0.01 min, and then held at 30% for 1.0min(1.2ml / min flow rate). Mobile phase A was 0.04% Trifluoroacetic Acid in water, mobile phase B was 0.02% Trifluoroacetic Acid in acetonitrile. The column used for chromatography was a 4.6*150mm X bridge 018 column (3.5um particles). Detection methods are diode array (DAD).Method 5: 0-60_AB_20min: HPLC( The gradient was 0-60% B in 16.00 min ,60-80% B in 3min, 80-0% B in 0.01 min, and then held at 0% for 1.0min(1.2 ml / min flow rate). Mobile phase A was 0.04% Trifluoroacetic Acid in water, mobile phase B was 0.02% Trifluoroacetic Acid in acetonitrile. The column used for chromatography was a 4.6*150mm X bridge 018 column (3.5um particles). Detection methods are diode array (DAD).Method 6: NEG5_95CD_6min-220 : LC / MS( The gradient was 5%B in 0.40min and 5-95% B at 0.40-3.40 min .hold on 95% B for 0.45min, and then 95-5%B in O.OImin, the flow rate was 0.8 ml / min. Mobile phase A was H2O+10mM NH4HCO3, mobilephase B was Acetonitrile. The column used for chromatography was a X bridge C18 2.1*50mm column (5um particles). Detection methods are diode array (DAD) detection .MS mode was negative electrospray ionization. MS range was 100-1000. NMR Methods H-NMR Method 1:

[0082] Samples for NMR analysis were prepared by complete dissolution of an appropriate amount of material in approximately 0.75 ml of deuterated solvent (MeOD, CDCI3 or D6- DMSO).1H-NMR spectra were recorded at 25°C using either a Varian INOVA 400MHz NMR Spectrometer equipped with a Varian ATB probe or a Varian INOVA 600MHz NMR Spectrometer equipped with a Varian 5mm 1H {C13 / N15} triple resonance cold probe. Variable number of scans (16-256) was applied using standard acquisition parameters. The pre-acquisition delay was set to 10 sec whenever NMR quantification was assessed. 'H-NMR Method 2:QNMR:Instrument NMR Bruker 400MHzBalance Mettler Toledo XPR205 / A d = 0.01 mg Solvent: DMSO-d6Standard: 3,5-Dimethyl-1 H-pyrazole 99.0%Formula for calculation:WISTD is the weight of internal standard (mg); Wsamis the weight of sample (mg); MWsamis the molecular weight of sample; MWISTD is the molecular weight of internal standard;Asam / AisTD is the area ratio between sample and internal standard; HISTD and nsamare the number of nucleus in the respective functional groups; W / WISTD% is the weight percentage of internal standard. DSC:XRPD:TGA:Water Content (oven temperature) Method:ICP-MS: 1. Sample solutionsWeigh about 50 mg of sample, transfer 2 mL of HNO3 into a 18 mL digestion vessel.Conduct the digestion using microwave digestion parameters which provided insection 2, cool down to room temperature, open the lid, then transfer the solution into a disposable plastic volumetric tube and rinse the digestion vessel with purified water at least thrice, dilute with water to 50 ml_.2. Microwave Digestion System Instrument: Anton Paar Multiwave 7000 Microwave Digestion System Conditions:3. Instrument: Agilent ICPMS 7800Residual Solvents by GC:XRPDThe XRPD spectra were collected in transmission mode on a Panalytical X'pert Pro instrument with X'celerator detector using a standard Aptuit method. The data were evaluated using the HighScore Plus software. The instrumental parameters used are listed below.Polarized light microscopyPolarized light microscopy analyses were run on a Leica DM microscope equipped with a double polarizer and digital camera. The method parameters are listed below.TGA and DSCThe TGA analyses were run on a TA Q5000 instrument. The DSC analyses were run on theTA Q2000 MDSC instrument. DSC and TGA method details are listed below:H PLC QC method (code H PLC / 2886 / 1 )Chemical SynthesisExperimental ProceduresExample 1A - Stage 1: Synthesis of INT-1C (methyl ester route)

[0083] To a solution of methyl 6-cyano-1 H-indole-2-carboxylate (SM-1) (18.67 g, 93.3 mmol, 1 eq, 1 wt, 1 vol) in THF (93.35 mL, 5 vol) was added a solution sodium hydroxide (5.22 g, 0.131 mol) in Water (93.35 mL, 5 vol) at 0-5°C (maintaining Tint< 20°C). The suspension was stirred for 3h at 20°C, during which time it became a clear yellow solution. The reaction was monitored by HPLC (3 min, Method 1, 220 nm): SM-1 < 0.2% a / a (Rt=2.138’); INT-1C 99.6% a / a (Rt=1.786'). The reaction mixture was cooled down to 0-5°C and acidified with a solution of hydrochloric acid (37%, 12 mL, 0.149 mol) in Water (93.35 mL, 5 vol). The mixture was stirred at 20°C for 20 minutes (pH< 2). The mixture was concentrated to overall 180 ml (about 10 vol) under reduced pressure Qacket temperature Tj 45-50°C) to remove THF. A white solid precipitated. The suspension was stirred at 20°C for 1 h and at 0-5°C for 30'. The white solid was filtered on a fiber glass filter P3. The wet cake was washed with water and it was dried under vacuum at 50 °C for 16 hours to give 17.26 g (99% mol yield) of INT-1C as a white solid.Example 1 B - Stage 1: Synthesis of INT-1C (ethyl ester route)1. Equip a 2 L of flask with stirrer, addition funnel and thermometer;2. 2-MeTHF (750 mL, 5 Vols) and MeOH (75 mL, 0.5 vol) were added into the flask at 25°C;3. SM-1 (150 g, 700 mmol, 1 eq) was added to the flask at 25°C;4. NaOH (42.0 g, 1.05 mol, 1.4 eq) was dissolved in added into H2O (750 ml_, 5 Vols) at 25°C to give clear solution;5. The prepared NaOH solution was dropwise added into the flask at 25°C;6. The resulting mixture was stirred at 25°C for 12 hours;7. IPC-LC-MS showed SM-1 was consumed, INT-1C as one main peak was detected;8. H2O (1.5 L, 10 Vols) was added into the reaction mixture;9. The reaction mixture was back-extracted with 2-MeTHF (1 L*2);10. The combined organic phases were separated, which was detected by HPLC_organic phase-1 ;11. The aqueous phase was cooled to 0°C, then it was acidified with 0.5N HCI to pH~3. Lots of solid precipitated, which was detected by HPLC_aqueous phase-1;12. The suspension was extracted with EtOAc (4 L*1 , 1 L*3). The combined organic phases were washed with brine (2 L), dried over Na2SC>4, filtered and filtrate was concentrated under reduced pressure to give a residue;13. To remove the water, the residue was added into THF (1 L), and then the mixture was dried in vacuum to give 105 g of INT-1C (564.01mmol, 80% yield, 99.4% purity) as a white solid.1H NMR (Method 2): (400 MHz, DMSO-cfe) 6 13.57 - 13.22 (m, 1 H), 12.44 - 12.23 (m, 1 H), 7.93 - 7.79 (m, 2H), 7.38 (dd, J = 1.3, 8.3 Hz, 1 H), 7.19 (d, J = 1.4 Hz, 1 H)Example 2A - Stage 2: Synthesis of INT-1A

[0084] INT-1C (EV-OPL001 -089-001 , 17.26 g, 92.7 mmol, 1 eq, 1 vol, 1 wt) was suspended in DCM (200 mL, 11.6 vol) at 20°C under nitrogen. DMF (15 mL, 0.9 vol) was added. Thionyl chloride (8.45 mL, 115.89 mmol) was added slowly at 20°C. The mixture was stirred at reflux (Tint=40°C) for 2 hours. The mixture was concentrated to overall 80 ml under reduced pressure (Tj 45-50°C). A white precipitate was observed. DCM (200 mL, 11.6 vol) was added. The mixture was heated to reflux for a few minutes to dissolve the solid giving a yellow solution. 1-cyclobutylmethanamine hydrochloride SM-2 (15.78 g, 0.130 mol) was added under stirring at20°C. The mixture was cooled down to 5-10°C with an ice-bath. Triethylamine (52 mL, 0.371 mol) was added dropwise (maintaining T<15-20°C). A white precipitate was observed (ammonium salts). The suspension was stirred at 20°C overnight. The reaction was monitored by HPLC (3 min, Method 1 , 220 nm): INT-1A 93.8% a / a (Rt=2.317'). Water (360 mL) was added at 0-5°C and the biphasic mixture was stirred at 20°C for 1 hour. The mixture was concentrated to overall 400 ml under reduced pressure (Tj 45-50°C). The white suspension was stirred for 1 hour at 20°C and at 10°C for 30'. The solid was filtered on a fiber glass filter P3. The wet cake was washed with water and it was dried under vacuum at 50 °C for 16 hours to give 23.72 g (>99% mol yield) of INT-1A as white solid.Characterisation:HPLC (3min, Method 1) - 97.2% a / aExample 2B - Stage 2: Alternative Synthesis of INT-1A1. Equip a 2 L of flask with stirrer, addition funnel and thermometer;2. DMF (1 L, 10 Vols) was added to the flask at 20°C;3. INT-1C (100 g, 537mmol, 1 eq), Reagent B (78.4 g, 645mmol, 1.2 eq) and DMAP (144 g, 1.18mol, 2.2eq) were added to the flask at 25°C under N2atmosphere;4. The mixture was cooled down to 0-10°C with an ice-bath;5. EDCI (206 g, 1.07 mol, 2 eq) was added to the mixture with an ice-bath over 20 min;6. The resulting mixture was stirred at 25°C for 12 hours;7. IPC-HPLC showed INT-1C was consumed and INT-1A as one main peak was detected; 8. The mixture was added dropwise H2O (10 L, 100 Vols) with an ice-bath, lots of white solid precipitate;9. The solid was filtered to give a wet compound;10. To remove the water, the wet solid was added into THF (2 L), then the mixture was concentrated under reduced pressure to give 123 g of INT-1A with 93.9% purity as a white solid.1H NMR (Method 2): (400 MHz, DMSO-cfe) 6 12.15 (br s, 1 H), 8.70 (br t, J = 5.7 Hz, 1 H), 7.89 - 7.77 (m, 2H), 7.35 (dd, J = 1.2, 8.3 Hz, 1 H), 7.25 (s, 1 H), 3.33 (t, J = 6.4 Hz, 2H), 2.60- 2.51 (m, 1 H), 2.06 - 1.92 (m, 2H), 1.87 - 1.78 (m, 2H), 1.77 - 1.67 (m, 2H)Example 3 - Stage 3: Synthesis of INT-1B - 100 q scale1. Equip a 5 L of flask with stirrer, addition funnel and thermometer;2. THF (600 ml_, 10 Vols) was added into the flask at 20°C;3. Under the atmosphere of N2, INT-1A (60 g, 1 eq, 83% assay) was added into flask in portions at 20°C;4. The suspension was cooled to 0°C (with an ice-bath);5. TMSCI (47.0 g, 54.8 ml_, 2.2 eq) was dropwise added into the reaction mixture at 0°C (no obvious exothermic phenomenon);6. The suspension was stirred at 0°C for 0.5 hour under N2atmosphere;7. LiAIH4(2.5 M, 393.4 mL, 5 eq) was dropwise added into the reaction mixture at 0°C over 1.5 hours to give a yellow solution (following exothermic process and hydrogen evolution);8. Then the mixture was heated to 65°C (inner temperature) and stirred for another 12 hours under N2atmosphere (following mild hydrogen evolution);9. IPC-HPLC showed INT-1A was consumed completely, 90% of INT-1B and 3.5% of INT- 1D were detected;10. The reaction mixture was cooled to 0°C under N2atmosphere;11 . Another THF (1 L, 10.67 Vols) was added into the mixture;12. It was quenched by addition Na2SO4. 10H2O (600 g, ~10 eq) at 0°C over 1.5 hours (mild reaction) under N2atmosphere;13. The resulting mixture was stirred at 20°C for 0.5 hour under N2atmosphere;14. 2 batches were combined and filtered through a pad of celite and filter cake was washed with THF (2 L*3), the combined filtrate was concentrated under reduced pressure to give 93 g of crude INT-1B with 86% assay;15. The crude INT-1B was trituration with EtOAc (186 mL, 2 Vols) at 60°C and stirred for 2 hours;16. The mixture was cooled to 20°C and stirred for another 12 hours17. It was filtered and filter cake was washed with EtOAc (93 mL, 1 vol), and the cake was dried in vacuum to give 72 g of INT-1B (containing 0.2% of INT-1D) with 99.6% purity and 98% assay as a white solid.1H NMR (Method 2): (400 MHz, DMSO-cfe) 3 10.78 (br s, 1 H), 7.32 (d, J = 8.0 Hz, 1H), 7.25 (s, 1 H), 6.89 (d, J = 8.1 Hz, 1 H), 6.16 (s, 1 H), 3.75 (d, J = 4.5 Hz, 4H), 2.53 - 2.51 (m, 1H), 2.50 - 2.47 (m, 1 H), 2.39 (td, J = 7.5, 14.8 Hz, 1 H), 2.03 - 1.91 (m, 2H), 1.87 - 1.71 (m, 4H), 1.67 - 1.56 (m, 2H)Example 4 - Stage 4: Synthesis of Compound of formula (I) (Cpd 1) - 100 q scale1. Equip a 2 L of flask with stirrer, addition funnel and thermometer;2. MeOH (720 mL, 10 Vols) was added to the flask at 20°C;3. Under the atmosphere of N2, INT-1B (72 g, 296mmol, 1 eq) was added into flask in portions at 20°C;4. INT-5 (63.4 g, 311 mmol, 1.05 eq) was added into the solution at 20°C;5. The suspension was heated to 70°C and stirred for 12 hours under N2atmosphere (yellow clear solution to white suspension);6. IPC-HPLC-1 showed 5% of INT-1 B and 5% of INT-5 remained, and 89% of Cpd 1 was detected;7. The reaction mixture was stirred at 70°C for another 12 hours;8. IPC-HPLC-2 showed 2.2% of INT-1 B and 2.9% of INT-5 remained, and 94% of Cpd 1 were detected;9. The reaction mixture was cooled to 20°C and stirred for another 12 hours;10. The mixture was filtered and filter cake was washed with MeOH (720 mL, 10vol), then the cake was dried in vacuum to give 105 g of Cpd 1 (252mmol, 85.3% yield, 99.8% purity) as an off-white solid.1H NMR (Method 2): (400 MHz, DMSO-cfe) 6 10.88 (s, 1 H), 9.22 (t, J = 6.3 Hz, 1 H), 9.01 (d, J = 7.0 Hz, 1 H), 8.04 (ddd, J = 1 .4, 6.9, 8.7 Hz, 1 H), 7.77 (d, J = 8.8 Hz, 1 H), 7.43 (dt, J = 1.0, 6.9 Hz, 1 H), 7.38 (d, J = 8.1 Hz, 1 H), 7.32 (s, 1H), 6.97 (dd, J = 1.0, 8.1 Hz, 1 H), 6.94 - 6.89 (m, 1 H), 6.21 (s, 1 H), 4.58 (d, J = 6.3 Hz, 2H), 3.78 (s, 2H), 2.51 (br s, 2H), 2.39 (quind, J = 7.4, 14.8 Hz, 1 H), 2.02 - 1.91 (m, 2H), 1.90 - 1.86 (m, 1 H), 1.86 - 1.68 (m, 2H), 1.67 - 1.55 (m, 2H)Example 5 - Preparation of a hemi-succinate salt of the compound of formula I

[0085] The compound for formula I (free base, 1.170 g, 2.82mmol) was weighed in a 50ml_ round bottom flask and then THF (25ml_, 21.4 vol) was added under stirring. No solubilization occurred within 1h and the dark amber slurry was left stirring for 1h at 23°C. After 1 h, succinic acid (335mg, 2.83 mmol) was added solid and few seconds later it started to flocculate and aggregate. After few minutes, the solid started to dissolve and to form a sticky solid on bottom of the flask. It was left stirring overnight.

[0086] The day after a dense slurry with a white precipitate was visible with still some residue on the bottom and it was left stirring other 6hrs. Gradually the residue disappeared. It was filtered with a syringe, deliquored over 2hrs and dried in oven at 45°C overnight.Output material: 1.127g (84% th. yield)NMR: stoichiometric ratio 1 :0.6

[0087] The powder was ground in the vial with a spatula and dried 24hrs at 45°C. Due to the 0.1% molar excess of succinic acid, the powder has been washed with 4ml_ of hot 2 propanol and filtered. Deliquored for 3 hours and collected.NMR analysis: stoichiometric ratio APksuccininic acid 1 :0.5. THF not quantifiable.XRPD

[0088] The sample shows the desired crystalline Form SUC1 , without traces of residual peaks of free base, see Figure 1.Purity by HPLC QC-method

[0089] QC-method (iSILA PD / 118613): 99.8%a / aNMR analysis

[0090] The solution1H-NMR analysis (Method 1 , DMSO-c / 6) confirmed salt formation with the API: counter ion stoichiometric ratio of 1:0.5. Residual solvents not detected (see Figure 2). Thermal analyses

[0091] An overlay of the TGA and DSC traces is reported in Figure 3.

[0092] The TGA profile, blue line, showed a single-step weight loss of 1.1 % w / w from ambient to 160°C.

[0093] The DSC trace, green line, showed a single endo event with onset at ~185°C.Example 6 - preparation of a crystalline Form 1 of the compound of formula I

[0094] The compound of formula I was suspended in preformed 1-PrOH / water 80 / 20 mixture (22.5ml_, 9vol) in a 50ml_ MultiMax reactor and heated to 75°C (internal temperature). Full dissolution was achieved with little solid above rim. The temperature was increased to 80°C for ca 15min and slightly more dissolution was observed. The temperature was then adjusted to 60°C at rate 0.5°C / min. The solution remained clear for an additional 5min. Form 1 seed of the compound of formula I (A / 4797 / 59 / 1, 15mg, 0.6%wt) was added. The mixture was aged for 1 5hrs at 60°C (turbidity was clearly visible) then temperature was set to 20°C at constant rate 0.1 °C / min. The slurry was aged at 20°C for additional 12hrs.

[0095] The solid was isolated by filtration (uncomplete transfer with mother liquors recycling, fast filtration), washed with fresh solvent mix. (1x1vol) and 1-PrOH / water 50 / 50 (1x1vol), then dried in vacuum at 50°C for about 5hrs:

[0096] Yield: 1.58g (yield corrected for intermediate sampling: 63%)

[0097] Drying was continued at 50°C overnight. A sample was then taken for HPLC analysis by QC method then it was finally dried at 60°C overnight:

[0098] MultiMax reactor and FBRM Lasentec traces are combined in Figure 3.

[0099] Analytical data of obtained product are reported below:XRPD: XRPD diffractogram was consistent with Form 1 (Figure 5).HPLC QC Method: purity 98.38 %a / a1H-NMR (Method 1 , DMSO-d6): Consistent with structure, residual 1-PrOH 0.2 %wt, DMSO -0.1 %wt.TGA Analysis: TGA trace of sample A / 4441 / 44 / 4 is reported in Figure 6; 0.4% weight loss from ambient to 185°C was detected.Optical Microscopy: columnar-like particles with weak agglomerates were observed (Figure 7).

Claims

Claims1. A process for preparing a compound of the formula I shown below, or a pharmaceutically acceptable salt thereof:the process comprising the following steps:(i-i) reacting Intermediate 1B having the structural formula I NT-1 B shown below:(INT-1B) with Intermediate 5 having the structural formula I NT-5 shown below:to form a compound of formula I; and(i-ii) optionally forming a pharmaceutically acceptable salt of the compound of formula I formed in step (i-i).

2. A process according to claim 1 , wherein the process further comprises forming the compound Intermediate 1 B (INT-1 B) by step (d-i) shown below:(d-i) reacting lntermediate-1A having the structural formula INT-1A shown below:(INT-1A) with a reducing agent to form Intermediate-1 B.

3. A process according to claim 2, wherein the reducing agent is from lithium aluminium hydride and the reaction is carried out in the presence of trimethylsilyl chloride.

4. A process according to claim 2 or claim 3, wherein the process further comprises forming the compound Intermediate 1A (INT-1A) by step (c-i) shown below:(c-i) reacting Intermediate-1 C having the structural formula INT-1C shown below:with Intermediate SM-2 having the structural formula SM-2 shown below:(SM-2) to form the compound lntermediate-1A.

5. A process according to claim 4, wherein the process further comprises forming the compound lntermediate-1C (INT-1C) by step (a-iii) shown below:(a-iii) hydrolysing ester group of the compound of the formula SM-1 shown below:to form lntermediate-1C; wherein Ri is (1 -4C)alkyl, preferably Ri is methyl or ethyl, more preferably Ri is ethyl.

6. A process according to claim 5, wherein the process further comprises forming the compound lntermediate-SM-1 (SM-1) by steps (a-i) and (a-ii) shown below:(a-i) reacting a compound of the formula A1 shown below:with a compound of the formula A2:wherein Ri and R2 are each independently selected from (1-4C)alkyl, and preferably Ri and R2 are methyl or ethyl, more preferably Ri and R2 are ethyl; to form a compound of the formula A3:(A3); and(a-ii) reducing the nitro group present in the compound of formula A3 formed in step (a-i) above and cyclising the compound to form a compound of formula SM-1:

7. A process of forming a compound Intermediate 1 B having the structure (INT-1 B) shown below:(INT-1B) the process comprising the step (d-i) shown below: (d-i) reacting lntermediate-1A having the structural formula INT-1A shown below:(INT-1A) with a reducing agent to form Intermediate-1 B.

8. A process according to claim 7, wherein the reducing agent is from lithium aluminium hydride and the reaction is carried out in the presence of trimethylsilyl chloride.

9. A process of forming a compound lntermediate-1A having the structure (INT-1A) shown below:(INT-1A) the process comprising the step (c-i):(c-i) reacting Intermediate-1 C having the structural formula INT-1C shown below:(INT-1C) with Intermediate SM-2 having the structural formula SM-2 shown below:to form the compound lntermediate-1A.

10. A process of forming a compound lntermediate-1C having the structure (INT-1C) shown below:(INT-1C) the process comprising the step (a-iii):(a-iii) hydrolysing the ester group of the compound of the formula SM-1 shown below:(SM-1) to form lntermediate-1C; wherein R1 is from (1-4C)alkyl , preferably R1 is methyl or ethyl, more preferably R1 is ethyl.

11. A process according to claim 10, wherein the process further comprises forming the compound lntermediate-SM-1 (SM-1) by steps (a-i) and (a-ii) shown below:(a-i) reacting a compound of the formula A1 shown below:with a compound of the formula A2:wherein Ri and R2 are each independently selected from (1-4C)alkyl, and preferably R1 and R2 are methyl or ethyl, more preferably R1 and R2 are ethyl; to form a compound of the formula A3:(A3); and(a-ii) reducing the nitro group present in the compound of formula A3 formed in step (a-i) above and cyclising the compound to form a compound of formula SM-1:(SM-1).

12. A compound of formula I formed by any one of the processes defined in claims 1 to 6.

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