BR112016009949B1 - NMDA ANTAGONIST PRODRUG COMPOUND, PHARMACEUTICAL COMPOSITION, AND USE OF A COMPOUND - Google Patents

Abstract

COMPOUND, PHARMACEUTICAL COMPOSITION, USE OF A COMPOUND, AND METHOD FOR TREATMENT OF DEPRESSION, PAIN AND RETT SYNDROME, SUICIDAL IDEATION, BIPOLAR DISORDER, OBSESSIVE COMPULSION DISORDER, SARINE GAS POISONING OR STATUS EPILEPTICS. Prodrugs of an NMDA antagonist, (S)-1-phenyl-2-(pyridin-2-yl)ethanamine, useful for the treatment of depression (particularly major depressive disorder) or pain; compositions comprising them and method for producing them.

Description

[001] This application claims priority to the U.S. provisional patent application. serial number 61/899,903, filed November 5, 2013, the entire description of which is incorporated herein by reference.

[002] This invention is directed to prodrugs of an NMDA antagonist, (S)-1-phenyl-2-(pyridin-2-yl)ethanamine, and their use in the treatment of depression and depressive disorders, particularly depressive disorder (MDD), and also for the treatment of pain (such as neuropathic pain). (S)-1-phenyl-2-pyridin-2-yl)ethanamine prodrugs may also be used to treat Rett Syndrome, suicidal ideation, bipolar disorder (including bipolar depression), obsessive compulsive disorder, Sarine gas and status epilepticus. The invention also relates to pharmaceutical compositions comprising prodrugs and processes for preparing them.

[003] Pain in one form or another is an acute part of human life. Wound pain and post-surgical pain is often temporary, but can be severe and may persist. Neuropathic pain, such as diabetic neuropathy and postherpetic neuralgia, severely impacts sufferers. Each year, tens of millions of people around the world, including patients at the end of their lives, suffer from pain without adequate treatment.

[001] Depression affects about 120 million people worldwide. Symptoms of depression include, but are not limited to, depressed mood or appetite, low energy and poor concentration, or any combination thereof. These problems can be chronic or recurrent and can result in a substantial impairment of an individual's ability to take care of their daily responsibilities. Depression is the leading cause of disability as measured by Years Lived with a Disability (YLDS) and the fourth leading contributor to the global burden of disease as measured by Disability Adjusted Life Years (DALYs; that is, the sum of years of potential life lost due to premature mortality and years of productive life lost due to disability) in 2000. By the year 2020, depression is projected to reach the number two ranking of DALYs calculated for all ages, in both men and women . Depression is now the second leading cause of DALYs in the 15-44 age category for both sexes combined.

[002] (S)-1-phenyl-2-(pyridin-2-yl)ethanamine dihydrochloride has been described for the treatment of MDD via intravenous infusion treatment (Gerard Sanacora et al., poster presented Dec. 2012 at the 51st Annual Meeting of the American College of Neuropsychopharmacology in Hollywood, Florida, USA. Other related descriptions include WO1993/020052, WO2000/056324 and WO2000/63175. For convenience, it will be helpful to be able to administer this medication as a oral dosage form. However, one concern with such an oral dosage form of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine dihydrochloride would be that it would be open to abuse intravenously, e.g. crushing of an oral dosage form of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine dihydrochloride, followed by immediate injection of the resulting crushed oral dosage form of (S)-1-phenyl-2 -(pyridin-2-yl)ethanamine dihydrochloride (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrugs are predicted to break down in a human body to provide (S) -1-phenyl-2-(pyridin-2-yl)ethanamine, so that when (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrugs are administered orally, they become break down to release a therapeutically effective dose of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. But, if a prodrug of the present invention is administered intravenously, the prodrug is predicted to release (S)-1-phenyl-2-(pyridin-2-yl)ethanamine to provide a lower Cmax, in a more lower rate than if the corresponding dose of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine had been administered intravenously. The use of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrugs would be predicted to improve the clinical safety profile of (S)-1-phenyl-2-(pyridin-2- yl)ethanamine (e.g., under conditions of overdose or drug abuse (e.g., pill crushing). So, in summary, putting (S)-1-phenyl-2-(pyridin-2-yl)ethanamine directly in an oral formulation could lead to abuse. The compounds of the present invention metabolize in vivo to provide (S)-1-phenyl-2-(pyridin-2-yl)ethamamine, but at a rate greater than the speed at which (S)-1-phenyl-2-(pyridin-2-yl)ethamamine is administered intravenously and therefore would not encourage potential abuse of (S)-1-phenyl-2-(pyridin-2-yl) )ethanamine.

DESCRIPTION OF THE DRAWINGS

[003] Figure 1a and 1b illustrate the prodrug conversion of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine (Example 5) to (S)-1-phenyl-2-( pyridin-2-yl)ethanamine during the incubation period in human intestinal fluid. In particular, Figure 1a illustrates prodrug concentration of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine (Example 5) (initial concentrations of 30, 100, 300 and 600 µM) when transforms into (S)-1-phenyl-2-(pyridin-2-yl)ethanamine during the incubation period in human intestinal fluid. Figure 1b illustrates the concentration of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine when it converts from the prodrug of (S)-1-phenyl-2-(pyridin-2-yl )ethanamine (Example 5, initial concentrations of 30, 100, 300 and 600 µm) during an incubation period in human intestinal fluid.

SUMMARY OF THE INVENTION

[004] The present invention provides a compound of formula (I): wherein R1 is C1-6 alkylC(O)O(C1-6 alkoxy), or AA is a peptide-linked natural amino acid or a pharmaceutically acceptable salt thereof.

[005] Alkyl is straight or branched chain and contains 1-6, eg 1-4 carbon atoms. Alkyl is, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl or tert-butyl.

[006] Alkoxy is straight or branched chain and contains 1-6, eg 1-4 carbon atoms. Alkoxy is, for example, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, sec-butoxy, iso-butoxy or tert-butoxy.

DETAILED DESCRIPTION OF THE INVENTION

[007] In one aspect, the present invention provides a compound of formula (I), wherein R1 is C1-6 alkylC(O)O(C1-6 alkoxy), for example, is C1-4 alkylC(O)O (C1-4 alkoxy). Examples include (CH3)2CHC(O)OCH2O, (CH3)2CHC(O)OCH(CH(CH3)2)O, CH3C(O)OCH(CH3)O or (CH3)2CHC(O)OCH(CH3)O .

[008] In another aspect, the present invention provides a compound of formula (I), in which R1 is

[009] In yet another aspect, the present invention provides a compound of formula (I), wherein R1 is (thus, the chiral center * has absolute configuration S).

[0010] In another aspect, the present invention provides a compound of formula (I), wherein AA is, for example, glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxylysine, arginine, histidine, phenylalanine, tyrosine, tryptophan, proline or hydroxyproline. In yet another aspect, AA is selected from the group consisting of tyrosine, tryptophan, phenylalanine, leucine, arginine, histidine, lysine and valine. In another aspect, AA is selected from the group consisting of tyrosine, arginine, histidine, lysine and valine. In yet another aspect, AA is valine.

[0011] A pharmaceutically acceptable salt is, for example, an acid addition salt such as a hydrochloride, hydrobromide, sulfate, phosphate, acetate, fumarate, maleate, tartrate, lactate, citrate, pyruvate, succinate, oxalate, methanesulfonate, p-toluenesulfonate, bisulfate, benzenesulfonate, ethanesulfonate, malonate, xinafoate, ascorbate, oleate, nicotinate, saccharinate, adipate, formate, glycolate, L-lactate, D-lactate, aspartate, malate, L-tartrate, D-tartrate, stearate, 2-furoate, 3-furoate, napadisylate (naphthalene-1,5-disulfonate or naphthalene-1-(sulfonic acid)-5-sulfonate, edisylate (ethane-1,2-disulfonate or ethane-1-(sulfonic acid)- 2-sulfonate, isethionate (2-hydroxyethylsulfonate), 2-mesitylenesulfonate, 2-naphthalenesulfonate, D-mandelate, L-mandelate, 2,5-dichlorobenzenesulfonate, cinnamate or benzoate.

[0012] A compound of formula (1), which is: (S)-(1-Phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)methyl isobutyrate; 2-Methyl-1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)propyl isobutyrate; 2-Methyl-1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)propyl isobutyrate diastereomer 1; 2-Methyl-1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)propyl isobutyrate diastereomer 2; 1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl acetate; 1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl acetate diastereomer 1; 1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl acetate diastereomer 2; 1-((S)-1-Phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl isobutyrate; 1-((S)-1-Phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl isobutyrate diastereomer 1; 1-((S)-1-Phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl isobutyrate diastereomer 2; (S)-1-((S)-2-Amino-3-methylbutanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide; (S)-1-((S)-2,6-Diaminohexanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide; (S)-1-((S)-2-Amino-3-(1H-imidazol-4-yl)propanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl )pyrrolidine-2-carboxamide; 2-((S)-2-((S)-1-((S)-2-Amino-3-(4-hydroxyphenyl)propanoyl)pyrrolidine-2-carboxamido)-2-phenylethyl)pyridine; 2-((S)-2-((S)-1-((S)-2-Amino-3-(1H-indol-3-yl)propanoyl)pyrrolidine-2-carboxamido)-2-phenylethyl)pyridine ; (S)-1-((S)-2-Amino-3-phenylpropanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide; or, (S)-1-((S)-2-Amino-4-methylpentanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide; or a pharmaceutically acceptable salt of either thereof.

[0013] The compounds of the invention can be prepared by adapting methods described in the art or by adapting methods described in the Examples. The compound (S)-1-phenyl-2-(pyridin-2-yl)ethanamine can be prepared, for example, by process methodology in EP-0633879 and the contents of that document are incorporated by reference.

[0014] The compounds of the present invention, wherein R1 is can be synthesized using a chemical process that proceeds through a 2-((S)-2-phenyl-2-((S)pyrrolid-2-incarboxamido)ethyl)pyridine intermediate.

[0015] Thus, in another aspect, the present invention provides the compound 2-((S)-2-phenyl-2-((S)-pyrrolid-2-incarboxamido)ethyl)pyridine: or a single salt, said salt being, for example, a hydrochloride, hydrobromide, sulfate, phosphate, acetate, methanesulfonate, p-toluenesulfonate, formate or benzoate salt.

[0016] In another aspect, the present invention provides the intermediate compound 2-((S)-2-phenyl-2-((S)-pyrrolidin-2-iocarboxamido)ethyl)pyridinium chloride.

[0017] A compound of formula (I), or a pharmaceutically acceptable salt thereof, may be used in the treatment of depression (such as major depressive disorder, eg treatment-resistant major depressive disorder).

[0018] A compound of formula (I), or a pharmaceutically acceptable salt thereof, can be used in the treatment of pain (such as neuropathic pain, chronic pain, phantom limb pain, nociceptive pain, psychogenic pain, incident pain or pain of penetration).

[0019] A compound of formula (I), or a pharmaceutically acceptable salt thereof, may be used in the treatment of Rett's Syndrome, suicidal ideation, bipolar disorder, obsessive compulsive disorder, sarine gas poisoning, or status epilepticus.

[0020] Thus, the present invention provides a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined herein for use in therapy. Therefore, the term "prodrug", as used herein, may refer to a compound of formula (I) in the form of a salt or in the form of a free base.

[0021] In another aspect, the present invention provides the use of a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined herein, in the manufacture of a medicament for use in therapy.

[0022] In another aspect, the present invention provides a method of administering (S)-1-phenyl-2-(pyridin-2-yl)ethanamine to a patient, said method comprising administering a compound of formula (I), of a pharmaceutically acceptable salt thereof, to a patient wherein said compound of formula (I) metabolizes in said patient to produce (S)-1-phenyl-2-(pyridin-2-yl)ethanamine.

[0023] In the context of the present specification, the term “therapy” also includes “prophylaxis”, unless there are specific indications to the contrary. The terms "therapeutically" and "therapeutically" should be interpreted in the same way.

[0024] Prophylaxis is expected to be particularly relevant to the treatment of persons who have suffered a previous episode of, or are considered to be at increased risk of, the disease or condition in question. Persons at risk of developing a particular disease or condition generally include those having a family history of the disease or condition, or those who have been identified by genetic testing or screening to be particularly susceptible to developing the disease or condition.

[0025] The invention further provides a method of treating depression, comprising administering to a patient in need thereof a therapeutically effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined herein.

[0026] The invention further provides a method of treating MDD, comprising administering to a patient in need thereof a therapeutically effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined herein.

[0027] The invention further provides a method of treating pain, comprising administering to a patient in need thereof a therapeutically effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined herein.

[0028] The invention further provides a method for treating neuropathic pain, chronic pain, phantom limb pain, nociceptive pain, psychogenic pain, incident pain or penetration pain, which comprises administering to a patient in need a therapeutically effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined herein.

[0029] The use of a compound of formula (I) or a pharmaceutically acceptable salt thereof for the treatment of depression.

[0030] The use of a compound of formula (I) or a pharmaceutically acceptable salt thereof for the treatment of pain.

[0031] For the aforementioned therapeutic uses, the dosage administered will, of course, vary with the compound employed, the mode of administration, the treatment desired, and the disorder indicated. For example, the daily dosage of the compound of the invention, if inhaled, can be in the range of 0.05 micrograms per kilogram of body weight (μg/kg) to 100 micrograms per kilogram of body weight (μg/kg). Alternatively, if the compound is administered orally, then the daily dosage of the compound of the invention can be in the range of 0.01 micrograms per kilogram of body weight (μg/kg) to 100 milligrams per kilogram of body weight (mg/kg).

[0032] The compounds of formula (I) and their pharmaceutically acceptable salts may be used as is, but will generally be administered in the form of a pharmaceutical composition, wherein the compound/salt of formula (I) (active ingredient) is in association with a pharmaceutically acceptable adjuvant, diluent or carrier. Conventional procedures for selecting and preparing suitable pharmaceutical formulations are described, for example, in "Pharmaceuticals - The Science of Dosage Form Designs", M. E. Aulton, Churchill Livingstone, 1988.

[0033] Depending on the mode of administration, the pharmaceutical composition will preferably comprise from 0.05 to 99% by weight (percent by weight), more preferably from 0.05 to 80% by weight, even more preferably from 0.10 to 70% by weight and even more preferably from 0.10 to 50% by weight of active ingredient, all percentages by weight being based on the total composition. In some embodiments, the pharmaceutical composition comprises 0.05% by weight of active ingredient. In some embodiments, the pharmaceutical composition comprises 20% by weight of active ingredient.

[0034] The present invention also provides a pharmaceutical composition comprising a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined herein, in association with a pharmaceutically acceptable adjuvant, diluent or carrier.

[0035] The invention further provides a process for preparing a pharmaceutical composition of the invention, which comprises mixing a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined herein, with a pharmaceutically acceptable adjuvant, diluent or carrier .

[0036] For oral administration, the compound of the invention may be mixed with an adjuvant or a carrier, for example, lactose, sucrose, sorbitol, mannitol; a starch, for example potato starch, corn starch or amylopectin; a cellulose derivative, a binder, for example gelatin or polyvinylpyrrolidone; and/or a lubricant, for example, magnesium stearate, calcium stearate, polyethylene glycol, a wax, a paraffin, etc., and then compressed into tablets. If coated tablets are required, the cores, prepared as described above, can be coated with a concentrated sugar solution, which may contain, for example, acacia, gelatin, talc and titanium dioxide. Alternatively, the tablet can be coated with a suitable polymer dissolved in a readily volatile organic solvent.

[0037] For the preparation of soft gelatin capsules, the compound of the invention can be mixed with, for example, a vegetable oil or polyethylene glycol. Hard gelatine capsules may contain granules of the compound employing one or other of the above mentioned excipients for tablets. Also liquid or semi-solid formulations of the compound of the invention can be filled into hard gelatine capsules.

[0038] The compounds of the invention can also be administered together with other compounds used for the treatment of the above conditions.

[0039] The following Examples illustrate the present invention. In the Examples, certain techniques were used and these are now described.

[0040] High pressure liquid chromatography (HPLC) was performed on a reverse phase (RP) column. A linear gradient was applied using for example mobile phase A (0.1% Formic Acid in MilliQ H2O or 0.1% NH3 in MilliQ H2O or 10 mM NH4OAc and 5% CH3CH in MilliQ H2O, or 0.05% trifluoric acid in MilliQ H2O, or NH4HCO3 in MilliQ H2O (10 mM)) and B (CH3OH or CH3CN). Mass spectrometer (MS) analyzes were performed in positive and/or negative ion mode using electrospray ionization (ESI ±), atmospheric pressure photo ionization (APPI ±) and/or atmospheric pressure chemical ionization (APCI ±).

[0041] Gas chromatography (GC) was performed on a GC equipped with a mass spectrometer (MS) or a flame ionization detector (FID). The MS ion source was either electron impact (EI) or a chemical ionization (CI, reagent gas: methane). For separation, a capillary column was used, eg DB-5MS (J&W Scientific). A linear temperature gradient was applied.

[0042] Supercritical Fluid Chromatography (SFC) was performed on a direct phase column. An isocratic flow was applied using mobile phase A (CO2) and, for example, mobile phase B (MeOH, EtOH or IPA).

[0043] Alternatively, high performance liquid chromatography (HPLC) was performed on a direct phase column. A linear gradient or isocratic flow was applied using, for example, mobile phase A (heptane) and B (EtOH or IPA).

[0044] NMR spectra were recorded on a 300 MHz (or higher field) NMR spectrometer equipped with a probe of suitable configuration. Spectra were recorded at room temperature unless otherwise noted. Chemical changes are given in ppm downfield and upfield from TMS (0.00 PPM). The following reference signals were used: TMS δ 0.00, or the residual solvent signal of DMSO-d6 δ 2.49, CD3OD δ 3.30, acetone d6 2.04, CDC13 δ 7.25, or D20 δ 4.79 (unless otherwise noted). Resonance multiplicities are indicated s, d, t, q, m, br and app for singlet, doublet, triplet, quartet, multiplet, broad and apparent, respectively. LIST OF ABBREVIATIONS DBU 1,8-diazabicyclo[5.4.0]undec-7-ene DCM Dichloromethane DEA Diethyl amine DIPEA Diisopropyl ethyl amine DMF Dimethylformamide DMSO Dimethylsulfoxide EtOAc Ethyl acetate HATU 2-(1H-7-Azabenzotriazol-1-yl )—1,1,3,3-tetramethyl uronium methanaminium hexafluorophosphate IPA iso-propanol MTBE Methyl tert-butyl ether rt room temperature, approximately 20 - 25 oC sat saturated T3P propane phosphonic anhydride

Example 1

[0045] (S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)methyl isoburate Step A Chloromethyl isobutyrate

[0046] To isobutyric acid (0.600 mL, 6.47 mmol) in DCM (6 mL) was added sodium bicarbonate (2092 mg, 24.91 mmol), tetrabutyl ammonium hydrogen sulfate (220 mg, 0.65 mmol) and water (6 mL). With rapid stirring, chloroethyl sulfochloridate (0.767 mL, 7.44 mmol) was added at rt and the reaction mixture was then stirred at rt overnight. The reaction mixture was then diluted with DCM (10 mL), washed with water (2 x 10 mL), dried over Na 2 SO 4 , filtered and concentrated to give chloromethyl isobutyrate (746 mg, 84%), which was used in the next step without more purification. 1H NMR (500 MHz, CDCl3) δ ppm 1.17 (m, 6H), 2.62 (m, 1H), 5.72 (s, 2H). STEP B (S)-(1-phenyl-2) -(pyridin-2-yl)ethylcarbamoyloxy)methyl isobutyrate

[0047] Cesium carbonate (1543 mg, 4.74 mmol) and tetrabutylammonium iodide (1749 mg, 4.74 mmol) were added to (S)-1-phenyl-2-pyridin-2-yl)ethanamine (313 mg , 1.58 mmol) in anhydrous DMF (8 mL) at rt. Carbon dioxide gas was bubbled into the reaction mixture for 30 min, followed by the addition of chloromethyl isobutyrate (647 mg, 4.74 mmol) in DMF (2 mL). The reaction mixture was stirred at rt with continued bubbling of CO2 gas overnight and continued stirring over the weekend without further addition of CO2 gas. The reaction mixture was diluted with water and extracted with EtOAc (3x), the combined organic layers were washed with water (2x), brine, dried over Na 2 SO 4 and concentrated. Purification was by column chromatography using a gradient of EtOAc in heptane (0 - 60%) to provide the title compound (239 mg, 44.2%). 1H NMR (500 MHz, DMSO-d6) δ ppm 1.00 (m, 6H), 2.46 (m, 1H, partially hidden in DMSO-d6), 3.09 (m, 2H), 5.04 (m, 1H), 5.52 (m, 2H), 7.17 - 7.24 (m, 3H), 7.27 - 7.34 (m, 4H), 7.65 (td, 1 H), 8.24 (d, 1H), 8.49 m, 1H) EXAMPLE 2 2-Methyl-1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)propyl isobutyrate

[0048] There are two different diastereomers of Example 2 due to the two possible configurations on the carbon atom identified with *. These are referred to as Example 2 diastereomer 1 and Example 2 diastereomer 2. Their absolute configurations have not been determined. 2-methyl-1-((4-methylsulfonyl)phenoxy)carbonyloxy)propyl isobutyrate (i) 4-(methylmercapto)phenol (8.46 g, 57.30 mmol) was taken up in DCM (60 mL) and then the reaction flask was cooled to 0 °C, followed by the addition of 1-chloro-2- methylpropyl carbonchloridate (4.27 mL, 28.65 mmol). A solution of 4-methylmorpholine (7.87 mL, 71.63 mmol) in DCM (40 mL) was added dropwise over 50 min at 0 °C and the resulting mixture was stirred at this temperature for 5 min and finally stirred at rt for 150 minutes. The reaction mixture was washed with water (2x), dried over Na2SO4, filtered and evaporated to give 1-chloro-2-methylpropyl 4-(methylthio)phenyl carbonate (13.84 g), which was used in the next step without further ado. purification. (ii) A mixture of 1-chloro-2-methylpropyl 4-(methylthio)phenyl carbonate (3.50 g, 12.74 mmol), silver(1) oxide (2.95 g, 12.74 mmol) and isobutyric acid (13.00 mL, 140.12 mmol) under an argon atmosphere was heated at 95 °C for 2 hours. The reaction mixture was cooled to rt and stirred at rt overnight, then diluted with MTBE, filtered through diatomaceous earth and washed with more MTBE. The combined filtrates were washed with water (4 x 25 mL), aq. sat. (2 x 25 mL), dried (Na 2 SO 4 ) and evaporated to give 3.56 g of 2-methyl-1-((4-(methylthio)phenoxy)carbonyloxy)propyl isobutyrate, which was used in the next step without further purification. (iii) 2-Methyl-1-((4-(methylthio)phenoxy)carbonyloxy)propyl isobutyrate (3.56 g, 10.91 mmol) was taken up in a mixture of aceton (30 mL) and water (7.50 mL), followed by addition of oxonium (13.41 g, 21.81 mmol) in portions over 5 min, then stirred at rt for 2 hours. The reaction mixture was filtered and the filtrate was washed with MTBE (2.50 mL), the volume was reduced to 50 mL (by distilling acetone) and then the resulting mixture was partitioned between MTBE and water. The aqueous layer was extracted with MTBE and the combined organics were dried over Na 2 SO 4 , filtered and evaporated to give 1.89 g of the title compound, which was used in the next step without further purification. STEP B 2-Methyl-1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)propyl isobutyrate

[0049] To a stirred mixture of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine (0.215 g, 1.08 mmol) and sodium bicarbonate (0.182 g, 2.17 mmol) in acetonitrile (3 mL) 2-methyl-1-((4-(methylsulfonyl)phenoxy)carbonyloxy)propyl isobutyrate (0.389 g, 1.08 mmol) in acetonitrile (2 mL) was added and the reaction was stirred at rt for 2 hours . Partitioned between EtOAc and sat aq NaHCO3, the organic layer was washed with sat aq NaHCO3, dried (Na2SO4) and evaporated to afford 413 mg of material, which was purified by gas chromatography using a gradient of EtOAc in heptane (0 - 50 %) to give 235 mg as a mixture of the two diastereomers of 2-methyl-1-(S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)propylisobutyrate.

[0050] Analysis and separation of diastereomers was done in Chiralpak AD-H, 4.6*250 mm; 5 µm, using 10% MeOH/90% CO2 at 3 mL/min flow and Chiralpak AD-H, 20*20 mm; 5 µm, using 10% MeOH/90% CO2 at 50 mL/min flow, respectively. Example 2, diastereomer 1

[0051] 105 mg of diastereomer 1 was obtained by chiral separation as the first diastereomer eluting at 99% optical purity. Rotamer mixture: 1H NMR (500 MHz, DMSO-d6) δ ppm 0.66 - 1.07 (m), 1.85 (m), 2.39 (m), 2.98 - 3.21 (m ), 5.01 (m), 6.31 (m), 7.10 - 7.26 (m), 7.26 - 7.37 (m), 7.56 - 7.73 (m), 8 .10 (d), 8.43 - 8.55 (m). At the. total protons in spectrum: 28. Major/minor rotamer ratio: 1/0.15. MS (ES+APCI+) m/z 385 (M+H)+ Example 2, diastereomer 2 xxx

[0052] 104 mg of diastereomer 2 was obtained as the second eluting diastereomer. Rotamer mixture: 1H NMR (500 MHz, DMSO-d6) δ ppm 0.48 - 0.69 (m), 0.75 - 0.87 (m), 0.87 - 1.07 (m), 1 .73 (m), 1.85 (m), 2.40 (m), 2.98 (m), 3.03 - 3.18 (m), 4.97 (m), 6.22 - 6 .38 (m), 7.13 - 7.26 (m), 7.26 - 7.37 (m), 7.65 (m), 7.78 (d), 8.06 (d), 8 .48 (m). At the. total spectrum protons: 28. Major/minor spin rotamers: 1/0.17. MS (ES+APCI+) m/z 385 (M+H)+. Optical purity = 99% Example 3 1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl acetate

[0053] There are two different diastereomers of Example 3 due to the two possible configurations on the carbon atom identified with *. These are referred to as Example 3 diastereomer 1 and Example 3 diastereomer 2. Their absolute configurations have not been determined. Step A: 1-((4-(methylsulfonyl)phenoxy)carbonyloxy)ethyl acetate (i) A mixture of 1-chloroethyl 4-(methylthio)phenyl carbonate (4.6 g, 18.65 mmol), silver(1) oxide (4.32 g, 18.65 mmol) and acetic acid (11 .75 mL, 205.1 mmol) under an argon atmosphere was heated at 95 °C for 2 h. The reaction mixture was cooled to rt and diluted with MTBE, filtered through diatomaceous earth and washed with more MTBE. The combined filtrates were washed with water (4 x 25 mL), aq. sat. (2 x 25 mL), dried (Na 2 SO 4 ) and evaporated to give 1.79 g of 1-((4-(methylthio)phenoxy)carbonyloxy)ethyl acetate, which was used in the next step without further purification. (ii) 1-((4-(Methylthio)phenoxy)carbonyloxy)ethyl acetate (1.79 g, 6.62 mmol) was taken up in a mixture of acetone (16 mL) and water (4.0 mL). Oxonium (8.14 g, 13.24 mmol) was added portionwise over 5 min, then stirred at rt overnight. The reaction mixture was filtered and the filtrate was washed with MTBE (2x50 mL), the volume reduced to about 50 mL (distilling acetone). The product was partitioned between MTBE and water. The aqueous layer was extracted with MTBE and the combined organics were dried (Na2SO4), filtered and evaporated to give 832 mg of the title compound and used in the next step without further purification. Step B: 1-((S)-1-phenyl-2-(pyridin-2-1)ethylcarbamoyloxy)ethyl acetate

[0054] To a stirred mixture of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine (198 mg, 1 mmol) and sodium bicarbonate (168 mg, 2.00 mmol) in acetonitrile (4 mL) 1-((4-(methylsulfonyl)phenoxy)carbonyloxy)ethyl acetate (302 mg, 1.00 mmol) in acetonitrile (1 mL) was added and the reaction was stirred at rt for 4 hours. The reaction mixture was then partitioned between EtOAc and sat. aq., the organic layer was washed with NaHCO 3 , brine, dried over Na 2 SO 4 and evaporated. This mixture was pre-purified by column chromatography using a gradient of EtOAc in heptane (0 - 50%) to provide 160 mg of the title compound as a mixture of its two diastereomers.

[0055] Analysis and separation of diastereomers were performed in Phenomenex LuxC4, 4.6*250 mm; 5 µm, using 30% MeOH+DEA/70% CO2 at 3 mL/min flow and Phenomenex LuxC4, 20*250 mm; 5 µm, using 25% MeOH+DEA/75% CO2 at 50 mL/min flow, respectively. Example 3, diastereomer 1

[0056] 29 mg of diastereomer 1 was obtained by chiral separation as the first diastereomer eluting at 99% optical purity. 1H NMR (500 MHz, DMSO-d6) δ ppm 1.31 (d, 3H), 1.92 (s, 3H), 3.00 - 3.16 (m, 2H), 5.00 (td, 1H), 6.52 (q, 1H), 7.14 - 7.25 (m, 3H), 7.30 (d, 4H) 7.65 (t, 1H), 8.13 (d, 1H), 8.50 (d, 1H). The spectrum signals were spread and the splitting of the DMSO signal could not be seen. 13C NMR (126 MHz, DMSO-d6) δ 19.6, 20.7, 44.6, 54.9, 88.7, 121.6, 123.8, 126.4, 126.9, 128.3, 136 .2, 143.0, 149.0, 153.2, 158.0, 168.6 ppm. MS (ES+) m/z 328 (M+H)+. Example 3, Diastereomer 2

[0057] 39 mg of diastereomer 2 was obtained as the second eluting diastereomer. 1H NMR (500 MHz, DMSO-d6) δ ppm 1.32 (d, 3H), 1.95 (s, 3H), 3.01 - 3.18 (m, 2H), 5.00 (td , 1H), 6.53 (q, 1h), 7.13 - 7.24 (m, 3H), 7.29 (d, 4H), 7.65 (t, 1H), 8.17 (d, 1H), 8.49d, 1H). The spectrum signals were spread and the splitting of the DMSO signal could not be seen. 13C NMR (126 MHz, DMSO-d6) δ 19.6, 20.7, 44.4, 54.9, 88.6, 121.6, 123.7, 126.4, 126.9, 128.3 , 136.2, 143.0, 149.0, 153.1, 158.0, 168.5. MS (ES+) m/z 329 (M+H)+. Optical purity 98%. Example 4 1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl isobutyrate

[0058] There are two different diastereomers of Example 4 due to the two possible configurations on the carbon atom identified with *. These are referred to as Example 4 diastereomer 1 and Example 4 diastereomer 2. Their absolute configurations have not been determined. Step A: 1-((4-(methylsulfonyl)phenoxy)carbonyloxy)ethyl isobutyrate (i) 4-(Methylmercapto)phenol (4.91 g, 35.00 mmol) was taken up in DCM (100 mL) and cooled to 0 °C. 1-Chloroethyl chloroformate (1.888 mL, 17.50 mmol) was added. A solution of 4-methylmorpholine (4.81 mL, 43.74 mmol)) in DCM (20 mL) was added dropwise over 10 min at 0 °C and the resulting mixture stirred at this temperature for 5 min. The reaction mixture was stirred at rt for 180 min, then diluted with DCM, washed with water (2x), dried over Na 2 SO 4 , filtered and evaporated to give 1-chloroethyl 4-(methylthio)phenyl carbonate (6.94 g) , which was used in the next step without further purification. (ii) A mixture of 1-chloroethyl 4-(methylthio)phenyl carbonate (2.3 g, 9.32 mmol), silver(1) oxide (2.160 g, 9.32 mmol) and isobutyric acid (9.51 ml, 102.55 mmol) under an argon atmosphere was heated at 95 °C for 2 h. The reaction mixture was cooled to rt and diluted with MTBE, filtered through diatomaceous earth, washed with more MTBE. The combined filtrates were washed with water (4 x 25 mL), sat. here (2 x 25 mL), dried (Na2SO4) and evaporated to give 1.16 g of product, which was used in the next step without further purification. (iii) 1-((4-(Methylthio)phenoxy)carbonyloxy)ethyl isobutyrate (1.16 g, 3.89 mmol) was taken up in a mixture of acetone (12 mL) and water (3.00 mL). Oxonium (4.78 g, 7.78 mmol) was added portionwise over 5 min, then stirred at rt overnight. The reaction mixture was filtered and the filtrate washed with MTBE (2 x 50 mL), the volume reduced to approximately 50 mL by distillation of acetone, then partitioned between MTBE and water. The aqueous layer was extracted with MTBE and the combined organics were dried over Na 2 SO 4 , filtered and evaporated to give 531 mg of the title compound, which was used in the next step without further purification. Step B 1-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyloxy)ethyl isobutyrate

[0059] To a stirred mixture of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine (0.300 g, 1.51 mmol) and sodium bicarbonate (0.254 g, 3.03 mmol) in acetonitrile HCl (6 mL) was added 1-((4-(methylsulfonyl)phenoxy)carbonyloxy)ethyl isobutyrate (0.500 g, 1.51 mmol) in acetonitrile (2 mL) and the reaction was stirred overnight. The mixture was partitioned between EtOAc and aq. sat., the organic layer was washed with sat. aq., brine, dried over Na2SO4 and evaporated to give 0.70 g, which was purified by column chromatography using a gradient of EtOAc in heptane (050%) to give the title compound (0.309 g, 57.2 g). %) as a mixture of the two diastereomers.

[0060] Analysis and separation of diastereomers were carried out in Phenomenex LuzC4, 4.6*250 mm; 5 µm, using 15% MeOH+DEA/85% CO2 at 3 mL/min flow and Phenomenex LuxC4, 20*250 mm; 5 µm using 15% MeOH+DEA/85% CO2 at 50 ml/min flow rate, respectively.

[0061] 25 mg of diastereomer 2 was obtained by chiral separation as the first diastereomer eluting in 99% optical purity. Rotamer mixture: 1H NMR (500 MHz, DMSO-d6) δ ppm 0.85 - 1.05 (m), 1.19 (d), 1.32 (d), 2.31 - 2.44 (m ), 2.98 - 3.20 (m), 4.94 - 5.07 (m), 6.48 (d), 6.52 (q), 7.15 - 7.25 (m), 7 .25 - 734 (m), 7.60 - 7.70 (m), 7.77 (d), 8.06 - 8.18 (m), 8.44 - 8.55 (m). At the. total protons in spectrum: 24. Major/minor ratio: 1:0.07. MS (ES+APCI+) m/z 357 (M+H)+. UV purity = 100%. Example 4, diastereomer 2

[0062] 25 mg of diastereomer 2 was obtained as second eluting isomer. Rotamer mixture: 1H NMR (500 MHz, DMSO-d6) d ppm 0.82 - 0.94 (m), 0.94 - 1.04 (m), 1.25 (d), 1.32 (d ) 2.24, - 2.32 (m), 2.34 - 2.44 (m), 3.00 - 3.17 (m), 5.02 (td), 6.48 (d), 6 .52 (q), 7.15 - 7.25 (m), 7.25 - 7.38 (m), 7.55 - 7.77 (m), 8.16 (d), 8.44 - 8.57 (m). At the. total spectrum protons: 24. Major/minor ratio: 1:0.08. MS (ES+APCI+) m/z 357 (M+H)+. UV purity = 100%. Optical purity = 99%.

[0063] Examples 5 to 12 use a common intermediate, the preparation of which is now described.

Preparation of Common Intermediate for Examples 5 to 12

[0064] 2-((S)-2-phenyl-2-((S)-pyrrolidin-2-iocarboxamido)ethyl) pyridinium dichloride (which may also be cited as; (S)-N-((S)1 -phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide dihydrochloride) STEP A 2-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidine-1-carboxylate

[0065] T3P (50% by weight in DMF, 0.86 mL, 1.47 mmol) was added dropwise to a solution of (1S)-1-phenyl-2-(pyridn-2-yl)ethan-1 - amine (200 mg, 0.737 mmol), Boc-L-proline (159 mg, 0.737 mmol) and DIPEA (0.64 Ml, 3.69 mmol) in CH 2 Cl 2 (7.4 mL) at 0 °C. The reaction was gradually warmed to rt while stirring overnight. The organic layer was washed twice with 5% aq. NaHCO 3 , once with brine, dried over Na 2 SO 4 , filtered and concentrated. The product was purified using a pressure column, eluting with a gradient of MeOH and CH2Cl2 (0% MeOH / 100% CH2CL2 ---> 10% MeOH / 90% CH2Cl2), yielding the title compound 305 mg (> 100%). 1H NMR (300 MHz, CDCl3): ppm 1.35 (s, 9H), 1.70 - 1.90 (m, 2H), 2.05 - 2.19 (m, 2H), 3, 13 (dd, 1H), 3.29 - 3.39 (m, 1H), 3.46 - 3.62 (m, 2H), 4.20 - 4.29 (m, 2H), 5, 39 (q, 1H), 6.91 (d, 1H), 7.09 - 7.14 (m, 1H), 7.16 - 7.23 (m, 5H), 7.49 (td , 1H), 8.45 - 8.59 (m, 1H). Alternative Method:

[0066] Boc-L-Pro-OH (2.0 g, 9.29 mmol) was dissolved in anhydrous DMF (15 mL), HATU 3.7 g, 9.76 mmol) and Hunig's base (5.3 mL, 30.66 mmol) were added and the mixture stirred at rt for 30 minutes. Then 2-[(2S)-2-azaniomyl-2-phenylethyl]pyridin-1-io dichloride (2.5 g, 9.29 mmol) was added to the solution and the mixture was stirred for 3 hours at rt. Water was added and the mixture was extracted 3x with EtOAc. The organic phase was washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The product was purified on a SiO4 column, eluting with a gradient (0% MeOH / 50% EtOAc / 50% heptane ---> 0% MeOH / 100% EtOAc/ 10% heptane ---> 10% MeOH / 90% EtOAc / 0% heptane) and then onto a C-18 column, eluting with a gradient of MeOH and water (0 to 100% MeOH), yielding 2.9 g (78% of the title compound. 1H NMR (300 MHz, CDCl3): ppm 1.35 (s, 9 H), 1.70 - 1.90 (m, 2 H), 2.05 - 2.19 (m, 2 H), 3.13 (dd, J = 13.8, 7.1 Hz, 1 H), 3.29 - 3.39 (m, 1 H), 3.46 - 3.62 (m, 2 H), 4.20 - 4.29 (m , 1 H), 5.39 (q, J = 6.8 Hz, 1 H), 6.91 (d, J = 7.3 Hz, 1 H), 7.09 - 7.14 (m, 1 H), 7.16 - 7.23 (m, 5 H), 7.49 (td, J = 7.63, 1.8 Hz, 1 H), 8.45 - 8.59 (m, 1 H STEP B (S)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide dihydrochloride

[0067] At 0 °C, (S)-tert-butyl 2-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidine-1-carboxylate (305 mg, 0.771 mmol) was dissolved in a solution of 4M HCl in 1,4-dioxane (7.7 mL, 30.8 mmol). The reaction was gradually warmed to rt while stirring overnight. Volatiles were removed under vacuum and the product was triturated in MTBE. The solid was recovered by filtration on a Büchner funnel, washed with MTBE and dried under vacuum, yielding 263 mg (93%) of the title compound as the dichlorohydride salt. 1H NMR (300 MHz, DMSO-d6): ppm 1.61 - 1.84 (m, 3H), 2.30 -2.36 (m, 1H), 3.05 - 3.11 (m, 2H, 3.39 - 3.47 (m, 2H), 4.05 - 4.20 (m, 2H), 5.34 (q, 1H, 7.17 - 7.41 (m, 5H) , 8.20 - 8.42 (m, 1H), 8.67 - 8.75 (m, 1H), 9.45 - 9.62 (m, 2H). Alternative Method:

[0068] tert-Butyl(2S)-2-{[(1S)-1-phenyl-2-(pyridin-2-yl)ethyl]carbamoyl}pyrrolidine-1-carboxylate (2.9 g, 7.33 mmol ) was dissolved in a solution of 4M HCl in 1,4-dioxane (73 mL, 293.31 mmol). The reaction mixture was stirred at rt for 3 h. Volatiles were removed under vacuum and the product was triturated in MTBE. The solid was recovered by filtration on a Büchner funnel, washed with MTBE and dried under vacuum, yielding 2.7 g (100%) of (2S-2-{1(1S)-1-phenyl-2-pyridin-1- io-2-yl)ethyl]carbamoyl}pyrrolidin-1-ium. 1H NMR (300 MHz, D2O): ppm 1.66 - 1.83 (m, 3H), 2.20 - 2.26 (m, 1H), 3.14 (t, J = 6.9 Hz , 2H), 3.34 (dd, J = 14.1, 8.2 Hz, 1 H), 3.51 (dd, J = 14.4, 7.3 Hz, 1 H), 4.18 (dd, J = 8.5, 6.2 Hz, 1 H), 5.11 (t, J = 7.9 Hz, 1 H), 7.06 - 7.10 (m, 2 H), 7 .15 - 7.21 (m, 3H), 7.61 - 7.70 (m, 2H), 8.23 (dt, J = 7.9, 1.5 Hz, 1H), 8, 37 (d, J = 5.8Hz, 1H). Example 5 (S)-1-((S)-2-Amino-3-methylbutanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide

[0069] The title compound was prepared as (S)-1-((S)-2-amino-3-methylbutanoyl)-N-((S)-1-phenyl-2-(pyridin) dihydrochloride -2-yl)ethyl)pyrrolidine-2-carboxamide. STEP A tert-Butyl (S)-3-methyl-1-oxo-1-((S)-2-((S)-1-phenyl-2- (pyridin-2-yl)ethylcarbamoyl (pyrroldin-1-yl)butan2-ylcarbamate

[0070] T3P (50% by weight in DMF, 0.83 mL, 1.42 mmol) was added dropwise to a solution of (S)-N-((S)-1-phenyl-2-(pyridin- 2-yl)ethyl)pyrrolidine-2-carboxamide dihydrochloride salt (263 m, 0.714 mmol), Boc-L-Valine (155 mg, 0.714 mmol) and DIPEA (0.62 mL, 3.57 mmol) in DCM (7 mL) at 0°C. The reaction was gradually heated at rt with stirring overnight. The organic layer was washed twice with 5% aqueous NaHCO 3 , once with brine, dried over Na 2 SO 4 , filtered and concentrated. The product was purified using a pressure column, eluting with a gradient of MeOH and CH2Cl2 (5% MeOH / 95% CH2Cl2 ---> 10% MeOH / 90% CH2Cl2), yielding the title compound 258 mg (73 %). 1H NMR (300 MHz, CDCl3): ppm 0.91 (d, 3H), 1.00 (d, 3H), 1.43 (s, 9H), 1.85 - 1.99 (m, 2H), 2.00 - 2.16 (m, 1H), 2.17 - 2.21 (m, 1H), 3.12 - 3.27 (m, 2H), 3.47 - 3.62 (m, 1H), 3.63 - 3.78 (m, 1H), 4.32 (dd, 1H), 4.58 (d, 1H), 5.23 - 5, 35 (m, 2H), 6.97 (d, 1H), 7.10 (dd, 1H), 7.14 - 7.30 (m, 5H), 7.50 (td, 1H ), 7.84 (d, 1H), 8.48 (dd, 1H), STEP B (S)-1-((S)-2-Amino-3-methylbutanoyl)-N-((S) -1-phenyl-2-(pyridin-2-yl)ethyl)pyrrodlidin-2-carboxamide dihydrochloride

[0071] tert-Butyl (S)-3-methyl-1-oxo-1-((S)-2-((S)-1-phenyl)2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin-1 -yl)butan-2-ylcarbamate (258 mg, 0.522 mmol) was dissolved in a 4M HCl solution in 1,4-dioxane (5.2 mL, 30.8 mmol). The reaction mixture was stirred overnight. Volatiles were removed under vacuum and the product was triturated in EtOAc. The solid was recovered by filtration in a Büchner funnel, then ground in Et2O. After filtering on a Büchner funnel, the solid was dried under vacuum, yielding 200 mg (82%) of the title compound as the dihydrochloride salt. The title compound as the dihydrochloride salt was then converted to the free base by techniques known to a person skilled in the art. Alternatively, the title compound can be prepared as a fumarate salt by methods known to one of ordinary skill in the art. 1H NMR (300 MHz, CD3OD): ppm 0.97 (d, 3H), 1.04 (d , 3H), 1.68 - 1.79 (m, 1H), 1.86 - 2.05 (m, 2H), 2.13 - 2.27 (m, 2H), 3.50 - 3.61 (m, 3H), 3.68 - 3.75 (m, 1H), 4.02 (d, 1H), 4.45 (dd, 1H), 5.40 (dd , 1H), 7.31 - 7.43 (m, 5H), 7.90 (t, 1H), 8.02 (d, 1H), 8.51 (td, 1H), 8 .75 (d, 1H). [M+H] + = 395.27 Example 6 (S)-1-((S)-2,6-Diaminohexanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl) ethyl)pyrrolidine-2-carboxamide.

[0072] The title compound was prepared as the trichloride, 2[(2S)-2-{[(2S)-1-[(2S)-,5-diazanioylexanoyl]pyridin-2-yl]formamido}-2- phenylethyl]pyridin-1-ium trichloride STEP A tert-Butyl(S)-6-oxo-6((S)-2-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin -1-yl)hexane-1,5-diyldicarbamate

[0073] N-alpha, N-epsilon-bis(tert-Butoxycarbonyl)-L-lysine dicyclohexylammonium salt (287 mg, 0.54 mmol) was dissolved in anhydrous DMF (4 mL). HATU (217 mg, 0.57 mmol) and DIPEA (0.21 mL, 1.19 mmol) were added and the mixture stirred at rt for 30 minutes. Then (2S)-2-{[(1S)-1-phenyl-2-(pyridin-1-io-2-yl)ethyl]carbamoyl}pyrroidin-1-ium dichloride (200 mg, 0.54 mmol ) was added to the solution and the mixture was stirred for 18 h at rt. Water was added and the mixture was extracted 3x with EtOAc. The organic phase was washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The product was purified on a SiO2 column, eluting with a gradient (O% MeOH / 50% EtOAc / 50% heptane -- -> 0% MeOH / 100% EtOAc / 0% heptane ---> 10% MeOH / 90% EtOAc / 0% heptane) then on a C-18 column, eluting with a gradient of MeOH and water (0 to 100% MeOH), yielding 80 mg (24%) of the title compound. 1H NMR (300 MHz, CDCl3): ppm 1.34 - 1.39 (m, 2H), 1.41 (s, 9H), 1.43 (s, 9H), 1.52 - 1.64 (m, 3H), 1.68 - 2.02 ( m, 4H), 2.08 - 2.22 (m, 2H), 3.02 - 3.16 (m, 3H), 3.20 - 3.28 (m, 1H), 3.48 - 3.57 (m, 1H), 3.60 - 3.70 ( m, 1H), 4.40 - 4.51 (m, 1H), 4.54 - 4.57 (m, 1H), 4.97 - 5.08 (m, 1H), 5.29 - 5.39 (m, 2H), 7.00 ( d, 1H), 7.10 - 7.32 (m, 6H), 7.52 (td, 1H), 7.86 (d, 1H), 8.49 (d, 1H).STEP B

[0074] Synthesis of 2-[(2S)-2-{[(2S)-1-[(2S)-2,5-diazanioylexanoyl] pyrrolidin-2-yl]formamido}-phenylethyl]pyridin-1-io trichloride

[0075] tert-Butyl (S)-6-oxo-6-((S)-2-((S-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin-1-yl)hexane- 1,5-diyldicrbamate (80 mg, 0.13 mmol) was dissolved in a solution of 4M HCl in 1,4-dioxane (1.6 mL, 6.4 mmol). The reaction was stirred at rt for 18 hours. The volatiles were removed under vacuum and the product was triturated in MTBE. The solid was recovered by filtration on a Büchner funnel, washed with MTBE and dried under vacuum. The solid was dissolved in water and freeze-dried to afford 60 mg ( 88%) of the title compound 1H NMR (300 MHz, D2O): ppm 1.23 - 1.35 (m, 2H), 1.46 - 1.59 (m, 3H), 1.65 - 1.80 (m, 4H), 2.04 - 2.13 (m, 1H), 2.80 (t, 2H), 3.31 - 3.43 (m, 2H), 3.47 - 3.57 (m, 2H), 4.16 (t, 1H), 4.28 (t, 1H ), 5.11 (t, 1 H), 7.10 - 7.13 (m, 2 H), 7.16 - 7.26 (m, 3 H), 7.68 - 7.73 (m, 2 H), 8.31 (td, 1 H), 8.42 ( dd, 1H); [M+H]+ = 424.2. Example 7 (S)-1-((S)-2-Amino-3-(1H-imidazol-4-yl)propanoyl)-N- ((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide

[0076] The title compound was prepared as 2-[(2S)-2-{[(2s)-1-[(2s)-2-azaniomyl-3-(1H-imidazol-1-io-4) trichloride -yl)propanoyl]pyrrolidin-2-yl]formamid}-2-phenylethyl]pyridin-1-ium trichloride STEP A tert-butyl (S)-3-(1H-imidazol-4-yl)-1-oxo-1 -((S)-2-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin-1-yl)propan-2-ylcarbamate

[0077] Boc-His-OH (166 mg, 0.65 mmol) was dissolved in anhydrous DMF (4 mL). HATU (260 mg, 0.68 mmol) and DIPEA (0.38 mL, 2.85 mmol) were added and the mixture stirred at rt for 30 minutes. Then 2-((S)-2-phenyl-2-((S)-pyrrolidin-2-iocarboxamido)ethyl)pridinium chloride (240 mg, 0.65 mmol) was added for 66 hours at rt. Water was added and the mixture was extracted 3x with EtOAc. The organic phase was washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The product was purified on a C-18 column, eluting with a gradient of MeOH and water (0 to 100% MeOH), yielding 100 mg (29%) of the title compound. 1H NMR (300 MHz, CDCl3): ppm 1.44 (s, 9H), 1.77 - 2.00 (m, 3H), 2.05 - 2.19 (m, 1H), 3. 03 - 3.14 (m, 2H), 3.23 (dd, 1H), 3.40 (dd, 1H), 3.52 - 3.58 (m, 1H), 4.50 - 4.62 (m, 2H), 5.43 - 5.50 (m, 2H), 6.91 - 6.97 (m, 2H), 7.13 - 7.27 (m, 5H ), 7.53 (t, 1 H), 7.65 (s, 1 H), 8.53 (d, 1 H), 8.67 (d, 1 H). STEP B 2-((S)-2-((S-1-((S)-2-Ammonium-3-(1H-imidazol-1-io-4-yl)propanoyl)pyrrolidine-2-carboxamido)- 2-phenylethyl)pyridinium trichloride

[0078] tert-Butyl (S)-3-(1H-imidazol-4-yl)-1-oxo-1-((S)-2-((S)-1-phenyl-2-(pyridin-2) -yl)ethylcarbamoyl)pyrrolidin-1-yl)propan-2-ylcarbamate (100 mg, 0.19 mmol) was dissolved in a solution of 4M HCl in 1,4-dioxane (2.3 mL, 9.39 mmol) . The reaction mixture was stirred at rt for 18 h. Volatiles were removed under vacuum and the product was triturated in MTBE. The solid was recovered by filtration on a Büchner funnel, washed with MTBE and dried under vacuum. The solid was dissolved in water and freeze-dried to afford 85 mg (69%) of the title compound. 1H NMR (300 MHz, D2O): ppm 1.50 - 1.58 (m, 1H), 1.69 - 1.76 (m, 2H), 2.07 - 2.14 (m, 1H ), 3.12 - 3.21 (m, 3 H), 3.38 (dd, 7.3 Hz, 1 H), 3.48 - 3.56 (m, 2 H), 4.32 (t , 1H), 4.43 (t, 1H), 5.14 (t, 1H), 7.08 - 7.12 (m, 2H), 7.15 - 7.23 (m, 3 H), 7.26 (s, 1H), 7.65 - 7.70 (m, 2H), 8.26 (td, 1H), 8.39 (d, 1H), 8.49 (d, 1H); [M+H]+ = 433.2; [M+Na]+= 455.1. Example 8 2-((S)-2-((S)-1-((S)-2-Amino-3-(4-hydroxyphenyl)propanoyl)pyrrolidine-2-carboxamido)-2-phenylethyl)pyridine dihydrochloride

[0079] The title compound may also be cited as: 2-[(2S)-2-{[(2S)-1-[(2S)-2-azanioyl-3-(4-hydroxyphenyl)propanoyl]pyrrolidin- 2-yl]formamido}-2-phenylethylpyridin-1-ium dichloride. STEP A tert-Butyl (S)-3-(4-hydroxyphenyl)-1-oxo-1-((S)-2-((S) 1-phenyl-2-(pyridin-1-yl)ethylcarbamoyl)pyrrolidin-1-yl)propan-2-ylcarbamate

[0080] Boc-Tyr-OH (229 mg, 0.81 mmol) was dissolved in anhydrous DMF (5 mL). HATU (325 mg, 0.86 mmol) and DIPEA (0.47 mL, 2.69 mmol) were added and the mixture was stirred at rt for 30 minutes. Then 2-((S)-2-phenyl-2-((S)-pyrrolidin-2-iocarboxamido)ethyl)pyridinium chloride (300 mg, 0.81 mmol) was added to the solution and the mixture was stirred for 66 h at rt. Water was added and the mixture was extracted 3x with EtOAc. The organic phase was washed with brine, dried over Na 2 SO 4 , filtered and concentrated under reduced pressure. The product was purified on a SiO 2 column, eluting with a (0% MeOH / 50% EtOAc / 50% heptane ---> 0% MeOH / 100% EtOAc / 0% heptane ---> 15% MeOH / 85% EtOAc / 0% heptane) then on a C-18 column, eluting with a gradient of MeOH and water (0 to 100% MeOH), yielding 180 mg (40%) of the title compound.1H NMR (300 MHz, CDCl3): ppm 1.44 (s, 9H), 1.73 - 2.02 (m, 3H), 2.16 - 2.22 (m, 1H), 2.92 - 3.09 (m, 4H), 3.35 - 3.42 (m, 1H ), 3.48 - 3.51 (m, 1H), 3.53 - 3.68 (m, 1H), 4.48 - 4.51 (m, 1H), 4.65 - 4. 73 (m, 1H), 5.06 - 5.14 (m, 1H), 5.43 (d, 1H), 6.61 (d, 1H), 6.86 (d, 2 H), 6.94 - 6.99 (m, 2H), 7.08 - 7.26 (m, 6H), 7.42 (dd, 1H), 8.49 (d, 1H) , 8.63 (s, 1H). STEP B 2-((S)-2-((S)-1-((S)-2-Ammonium-3-(4-hydroxyphenyl)propanoyl)pyrrolidine-2-carboxamido)-2-phenylethyl)pyridinium dichloride

[0081] tert-Butyl (S)-3-(4-hydroxyphenyl)-1-oxo-1-((S)-2-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl )pyrrolidin-1-yl-)propan-2-ylcarbamate (180 mg, 0.32 mmol) was dissolved in a 4M HCl solution in 1,4-dioxane (3.2 mL, 12.89 mmol). The reaction was stirred at rt for 18 hours. Volatiles were removed under vacuum and the product was triturated in MTBE. The solid was recovered by filtration on a Büchner funnel, washed with MTBE and dried under vacuum. The solid was dissolved in water and freeze-dried to afford 150 mg (88%) of the title compound. 1H NMR (300 MHz, D2O): ppm 1.48 - 1.57 (m, 1H), 1.68 - 1.73 (m, 2H), 1.98 - 2.05 (m, 1H ), 2.68 - 2.76 (m, 1H), 2.93 - 3.00 (m, 1H), 3.10 - 3.19 (m, 1H), 3.40 - 3, 63 (m, 3H), 4.20 - 4.28 (m, 2H), 5.14 (t, 1H), 6.65 (d, 2H), 6.96 (d, 2H ), 7.13 - 7.22 (m, 5H), 7.63 - 7.66 (m, 2H), 8.19 - 8.22 (m, 1H), 8.40 (d, 1 H); [M+H]+ = 459.2. Example 9 2-((S)(-2-((S)-1-((S)-2-Amino-3-(1H-indol-3-yl)propanoyl)pyrrolidine-2-carboxamido)-2- phenylethyl)pyridine dihydrochloride

[0082] The title compound can also be cited: 2-[(2S)-2-{[(2S)-1-[(2S)-2-azanioyl-3-(1H-indol-3-yl)propanoyl ]pyrrolidin-2-yl]formamido{-2-phenylethyl]pyridin-2-ium dichloride.STEP A tert-Butyl (S)-3-(1H-indol-3-yl)-1-oxo-1-(( S)-2-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin-1-yl)propan-2-ylcarbamate

[0083] Boc-Trp-OH (207 mg, 0.68 mmol) was dissolved in anhydrous DMF (4 mL). HATU (271 mg, 0.71 mmol) and DIPEA (0.39 ml, 2.24 mmol) were added and the mixture was stirred at rt for 30 minutes. Then (2S)-2-{[(1S)-1-phenyl-2-(pyridin-1-io-2-yl)ethyl]carbamoyl}pyrrolidin-1-ium dichloride (250 mg, 0.68 mmol ) was added and the mixture was stirred for 38 hours at rt. Water was added and the mixture was extracted 3x with EtOAc. The organic phase was washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The product was purified on a SiO2 column, eluting with a gradient of (0% MeOH / 50% EtOAc / 50% heptane ---> 0% MeOH / 100% EtOAc / 0% heptane ---> 15% MeOH / 85 % EtOAc / 0% heptane), yielding 410 mg (Quantitative) of the title compound. 1H NMR (300 MHz, CDCl3): ppm 1.44 (s, 9H), 1.77 - 1.89 (m, 3H), 2.14 - 2.24 (m, 1H), 3, 03 - 3.24 (m, 4H), 3.28 - 3.36 (m, 2H), 3.54 - 3.65 (m, 1H), 4.52 - 4.58 (m, 1H), 4.79 - 4.88 (m, 1H), 5.12 - 5.27 (m, 1H), 5.34 - 5.41 (m, 1H), 6.63 ( d, 1H), 6.94 - 7.31 (m, 8H), 7.38 - 7.53 (m, 3H), 7.62 - 7.67 (m, 1H), 8, 59 (d, 1H), 9.87 (s, 1H), STEP B 2-((S)-2-((S)-1-((S)-2-Ammonium-3-(1H- indol-3-yl)propanoyl)pyrrolidine-2-carboxamido)-2-phenylethyl)pyridinium dichloride

[0084] tert-Butyl (S)-3-(1H-indol-3-yl)-1-oxo-1-((S)-1phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin-1- yl)propan-2-ylcarbamate (395 mg, 0.68 mmol) was dissolved in a solution of 1 M HCl in Et2O (27.0 mL, 27.20 mmol). The reaction mixture was stirred at rt for 4 h. The product was triturated in Et2O and the solid was filtered off on a Büchner funnel, washed with Et2O and dried under vacuum. The solid was dissolved in water and freeze-dried to afford 175 mg (44%) of the title compound. 1H NMR (300 MHz, D2O): ppm 1.41 - 1.53 (m, 1H), 1.63 - 1.72 (m, 2H), 1.93 - 2.04 (m, 1H ), 2.85 (dd, 1H), 2.94 - 3.55 (m, 5H), 4.19 - 4.31 (m, 2H), 5.08 (t, 1H), 6.90 - 7.31 (m, 9H), 7.38 (d, 1H), 7.55 - 7.58 (m, 2H), 8.15 (t, 1H), 8, 31 (d, 1H); [M+H]+ = 482.2, [M+Na]+ = 504.1. Example 10 (S)-1-((S)-2-Amino-3-phenylpropanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide

[0085] The title compound was prepared as 2-[(2S)-2-{[(2S)-1-[(2S)-2-azanioyl-3-phenylpropanoyl]pyrrolidin-2-yl]formamido}-2 - phenylethyl]pyridin-1-ium dichloride.STEP A tert-Butyl (S)-1-oxo-3-phenyl-1-((S)-2-((S)-1-phenyl-2-(pyridin- 2-yl)ethylcarbamoyl)pyrrolidin-1-yl)propan-2-ylcarbamate

[0086] Boc-Phe-OH (180 mg, 0.68 mmol) was dissolved in anhydrous DMF (4 mL). HATU (271 mg, 0.71 mmol) and DIPEA (0.39 ml, 224 mmol) were added and the mixture was stirred at rt for 30 minutes. Then (2S)-2-{[(1S)-1-phenyl-2-pyridin-1-io-2-yl)ethyl]carbamoyl}pyrrolidin-1-ium dichloride (250 mg, 0.68 mmol) was added to the solution and the mixture was stirred for 18 h at rt. Water was added and the mixture was extracted 3x with EtOAc. The organic phase was washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The product was purified on a SiO2 column, eluting with a gradient (0% MeOH / 50% EtOAc / 50% heptane ---> 0% MeOH / 100% EtOAc / 0% heptane ---> 15% MeOH / 85% EtOAc / 0% heptane), then on a C-18 column, eluting with a gradient of MeOH and water (0 to 100% MeOH), yielding 170 mg (46%) of the title compound. 1H NMR (300 MHz, CDCl3): ppm 1.44 (s, 9H), 1.73 - 1.91 (m, 3H), 2.10 - 2.19 (m, 1H), 3, 10 - 3.40 (m, 3H), 3.45 - 3.61 (m, 2H), 4.27 - 4.35 (m, 1H), 4.50 - 4.56 (m, 2H). 1H), 4.60 - 4.69 (m, 1H), 5.17 - 5.41 (m, 3H), 6.93 - 7.03 (m, 2H), 7.06 - 7.32 (m, 9 H), 7.47 - 7.56 (m, 1 H), 7.82 (d, 1 H), 8.48 (d, 1 H), STEP B 2-(( S)2-((S)-1-((S)-2-Ammonium-3-phenylpropanoyl)pyrrolidine-2-carboxamido)-2-phenylethyl)pyridinium dichloride

[0087] tert-Butyl (S)-1-oxo-3-phenyl-1-((S)2-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin-1- yl)propan-2-ylcarbamate (170 mg, 0.31 mmol) was dissolved in a solution of 1 M HCl in Et2O (12.5 mL, 12.53 mmol). The reaction mixture was stirred at rt for 18 hours. The product was triturated in Et2O. The solid was recovered by filtration on a Büchner funnel, washed with Et2O and dried under vacuum. The solid was dissolved in water and freeze-dried to afford 150 mg (93%) of the title compound. 1H NMR (300 MHz, D2O): ppm 1.39 - 1.48 (m, 1H), 1.58 - 1.65 (m, 2H), 1.92 - 1.99 (m, 1H ), 2.66 - 2.74 (m, 1H), 2.95 - 3.10 (m, 2H), 3.29 - 3.45 (m, 3H), 4.15 - 4, 27 (m, 2H), 5.09 (t, 1H), 6.97 - 7.17 (m, 10H), 7.59 - 7.64 (m, 2H), 8.18 ( t, 1H), 8.35 (d, 1H); [M+H]+ = 443.3, [M+Na]+ = 465.2, Example 11 (S)-1-((S)-2-Amino-4-methylpentanoyl)-N-((S) -1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide

[0088] The title compound was prepared as 2-[(2S)-2-{[(2S)-1-[(2S)-2-azanioyl-4-methylpentanoyl]pyrrolidin-2-yl]formamide} dichloride -2-phenylethyl]pyridin-1-yl dichloride. STEP A tert-butyl (S)-4-methyl-1-oxo-1-((S)-2-((S)-1phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin-1-yl) pentan-2-ylcarbamate

[0089] N-tert-Butoxycarbonyl)-L-leucine (157 mg, 0.68 mmol) was dissolved in anhydrous DMF (4 mL). HATU (271 mg, 0.71 mmol) and DIPEA (0.39 mL, 2.24 mmol) were added and the mixture was stirred at rt for 30 minutes. Then (2S)-20-{[(1S)-1-phenyl-2-(pyridin-1-io-2-1)ethyl]carbamoyl}pyrrolidin-1-ium dichloride (250 mg, 0.68 mmol ) was added to the solution and the mixture was stirred for 18 hours at rt. Water was added and the mixture was extracted 3x with EtOAc. The organic phase was washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The product was purified on a SiO2 column, eluting with a gradient (0% MeOH / 50% EtOAc / 50% heptane ---> 0% MeOH / 100% EtOAc / 0% heptane ---> 15% MeOH / 85 % EtOAc / 0% Heptane) then on a C-18 column, eluting with a gradient of MeOH and water (0 to 100% MeOH), yielding 200 mg (58%) of the title compound. 1H NMR (300 MHz, CDCl3): ppm 0.91 (d, 3H), 0.98 (d, 3H), 1.34 - 1.52 (m, 1H), 1.41 (s, 9H), 1.70 - 1.84 (m, 2H), 1.85 - 1.96 (m, 3H), 2.11 - 2.18 (m, 1H), 3.07 - 3.27 (m, 2H), 3.47 - 3.56 (m, 1H), 3.61 - 3.71 (m, 1H), 4.43 - 4.56 (m, 2H ), 5.14 - 5.18 (m, 1H), 5.26 - 5.34 (m, 1H), 6.98 (d, J = 7.7 Hz, 1H), 7.08 - 7.25 (m, 5H), 7.52 (t, 1H), 7.83 (d, 1H), 8.48 (d, 1H), STEP B 2-((S)- 2-((S)-1-((S)-2-Ammonium-4-methylpentanoyl)pyrrolidine-2-carboxamido)-2-phenylethyl)pyridinium dichloride

[0090] tert-butyl (S)-4-methyl-1-oxo-1-((S)-2-((S)-1-phenyl-2-(pyridin-2-yl)ethylcarbamoyl)pyrrolidin-1 -yl)pentan-2-ylcarbamate (200 mg, 0.39 mmol) was dissolved in a solution of 1 M HCl in Et2O (15.7 mL, 15.7 mmol). The reaction was stirred at rt for 18 h. The product was triturated in Et2O. The solid was recovered by filtration on a Büchner funnel, washed with Et2O and dried under vacuum. The solid was dissolved in water and freeze-dried to afford 130 mg (69%) of the title compound. 1H NMR (300 MHz, D2O): ppm 0.72 (d, 6H), 1.31 - 1.49 (m, 4H), 1.65 - 1.74 (m, 2H), 1. 93 - 2.02 (m, 1H), 3.23 - 3.49 (m, 4H), 3.99 - 4.04 (m, 1H), 4.16 - 4.21 (m, 1H), 5.07 (t, 1H), 7.08 - 7.20 (m, 5H), 7.63 - 7.67 (m, 2H), 8.22 (td, 1H ), 8.37 (dd, 1H); [M+H]+ = 409.2, [M+Na]+ = 431.2, Example 12 2-[(2S)-2-{[(2S)-1-[(2S)-2-Azanioyl- 5-{[Azanioyl(iminioyl)methyl]amino}pentanoyl]-pyrrolidin-1-yl]formamido}-2-phenylethyl]pyridin-1-ium tetrachloride. STEP A tert-Butyl N-[(1Z)-{[(4S)-4-{[tert-butoxy)carbonyl]amino}-5-oxo-5-[(2S)-2-{[(1S)- 1-phenyl-2-(pyridin-2-yl)ethyl]carbamoyl}pyrrolidin-1-yl]pentyl]amino }({[(tert-butoxy)carbonyl]imino})methyl]carbamate

[0091] Boc-Arg(Boc) 2 -OH (644 mg, 1.36 mmol) was dissolved in anhydrous DMF (7 mL). HATU (542 mg, 1.43 mmol) and DIPEA (0.78 mL, 4.48 mmol) were added and the mixture stirred at rt for 30 minutes. Then (2S0-2-{[(1S)-1-phenyl-2-(pyridin-1-yl-1-yl)ethyl]carbamoyl}pyrrolidin-1-yl dichloride (500 mg, 1.36 mmol) was added to the solution and the mixture was stirred for 18 h at rt. Water was added and the mixture was extracted 3x with EtOAc. The organic phase was washed with brine, dried over Na 2 SO 4 , filtered and concentrated under reduced pressure. The product was purified on a SiO2 column, eluting with a gradient (0% MeOH / 50% EtOAc / 50% heptane ---> 0% MeOH / 100% EtOAc / 0% heptane ---> 10% MeOH ] 90% EtOAc / 0 % heptane) then on a C-18 column, eluting with a gradient of MeOH and water (0 to 100% MeOH), yielding 200 mg (20%) of the title compound.1H NMR (300 MHz, CDCl3): ppm 1.43 (s, 9 H), 1.46 (s, 9 H), 1.51 (s, 9 H), 1.57 - 1.76 (m, 4 H), 1.86 - 1, 99 (m, 3H), 2.12 - 2.25 (m, 1H), 3.11 (dd, 1H), 3.23 - 3.30 (m, 1H), 3.58 - 3.95 (m, 4H), 4.42 (t, 1H), 4.56 (d, 1H), 5.31 - 5.38 (m, 2H), 6.98 (d , 1H), 7.17 - 7.33 (m, 5H), 7.54 (t, 1H), 7.93 (d, 1H), 8.56 (d, 1H), STEP B 2-[(2s)-2-{[(2s)-1-[(2S)-2-Azanioyl-5-{[azanioyl(iminioyl)methyl]amino)(pentanoyl]pyrrolidin-2-yl]formamide} -2-phenylethyl]pyridin-1-ium tetrachloride

[0092] tert-butyl N-[(1Z)-{[(4S)-4-{[(tert-butoxy)carbnoyl]amino}-5-oxo-5-[(2S)-2-{[(1S) )-1-phenyl-2-(pyridin-2-yl)ethyl]carbamoyl}pyrrolidin-1-yl]pentyl]amino}({[(tert-butoxy)carbonyl]imino})methyl]carbamate (200 mg, 0 .27 mmol) was dissolved in a solution of HCl M in Et2O (5.3 mL, 10.64 mmol). The reaction was stirred at rt for 18 hours. The product was triturated in Et2O. The solid was recovered by filtration on a Büchner funnel, washed with Et2O and dried under vacuum. The solid was dissolved in water and freeze-dried to afford 140 mg (88%) of the title compound. 1H NMR (300 MHz, D2O): ppm 1.31 - 1.57 (m, 3H), 1.66 - 1.78 (m, 4H), 2.00 - 2.10 (m, 1H ), 2.99 (t, 2H), 3.28 - 3.40 (m, 4H), 4.16 (t, 1H), 4.26 (t, 1H), 5.09 ( t, 1H), 7.10 - 7.13 (m, 2H), 7.16 - 7.21 (m, 3H), 7.67 - 7.71 (m, 2H), 8, 27 (t, 1H), 8.40 (d, 1H); [M+H]+ = 452.2.

BIOLOGICAL ACTIVITY

[0093] Prodrugs described herein are contemplated to be administered orally by those suffering from depression or pain.

Example 13

[0094] This example illustrates that different prodrugs of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine, wherein R1 is C1-6 alkylC(O)O(C1-6 alkoxy), can be used to obtain different conversion rates (i.e., slow or fast) for (S)-1-phenyl-2-(pyridin-2-yl)ethanamine to verify a suitable PK profile. As a result, varying R1 to produce different prodrugs results in different pharmacokinetic profiles of (S)-1-phenyl-2-(pyridin-2-yl))ethanamine. Furthermore, this Example illustrates that no loss in oral exposure is expected when a prodrug is converted to the free base. Conversion of a prodrug, where R1 is C1-6 alkylC(O)O(C1-6 alkoxy), to (S)-1-phenyl-2-(pyridin-2-yl)ethanamine is expected to occur via an initial enzymatic hydrolysis of a functional group, such as an ester, followed by a spontaneous conversion to (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. The enzymes involved are expected to be several high-capacity, non-specific esterases, which can be shown by inhibiting the conversion with a non-selective esterase inhibitor, but not inhibiting the conversion using selective inhibitors. Such esterases are expected to be distributed throughout the human body. Human intestinal fluid (HIF), human liver S9 fraction, and human whole blood have been used to examine the pharmacokinetic properties of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrugs as well as the rate of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine formation and extent of formation in different body compartments. The rate of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine formation of different (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrugs differs significantly in all assays tested, as shown in Table 1.Table 1

[0095] The in vitro results, shown in Table 1, show that different plasma pharmacokinetic profiles of (S)-1-phenyl-1-(pyridin-2-yl)ethanamine can be achieved using different prodrugs of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. As a result, the selection of a particular prodrug will allow different pharmacokinetic profiles of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine to be obtained, i.e. different prodrugs can be used to achieve slow or rapid conversion to (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. The Human Intestinal Fluids (HIF), Human Liver and Human Blood assays used to generate the results shown in Table 1 are described in Malmborg J & Ploeger BA, J. Pharmacol Toxicol Methods (2013) May-June 67 (3) 203-13, which is incorporated herein by reference.

Example 14

[0096] This example illustrates that different prodrugs of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine, in which R1 is can be used to obtain different conversion rates (i.e., slow or fast) for (S)-1-phenyl-2-(pyridin-2-yl)ethanamine to verify a suitable PK profile. As a result, varying R1 to produce different prodrugs results in different pharmacokinetic profiles of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. Furthermore, this Example illustrates that there is no expected loss on oral exposure when a prodrug is converted to free base.

[0097] Conversion of a prodrug into (S)-1-phenyl-2-(pyridin-2-yl)ethanamine of a compound of formula (I) in which R1 is: is expected to occur via enzymatic hydrolysis at the C-terminus of proline, releasing a dipeptide and (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. The enzyme involved is expected to be dipeptidyl peptidase IV (DPPIV), which can be shown by inhibiting the conversion with a selective inhibitor of this enzyme. DPPIV is expected to be distributed throughout the human body. Human Intestinal Fluid (HIF), human liver S9 fraction, and human whole blood were used to examine the pharmacokinetic properties of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrugs, as well as the rate of formation and extent of formation of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine in different body compartments. Caco-2 cells were used to assess the permeability and uptake potential of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrugs. The rate of formation of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine from different prodrugs of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine differed in assays tested, especially in human blood, as shown in Table 2. The different permeability exhibited by different prodrugs of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine suggests that systemic exposure of the prodrug of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine will vary depending on the prodrug chosen.Table 2

[0098] In vitro assays show that different plasma pharmacokinetic profiles of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine can be achieved using different prodrugs. As a result, different pharmacokinetic profiles of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine can be achieved by using different prodrugs.

Example 15

[0099] This example illustrates that oral doses of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrugs have a similar pharmacokinetic profile to a 1-hour IV infusion of (S)- 1-phenyl-2-(pyridin-2-yl)ethanamine.

[00100] Based on in vitro data, (S)-1-phenyl-2-(pyridin-2-yl)ethanamine (lanicemin) is projected to have good oral availability (>75%) in man, but a higher acceptable Cmax when given as an intravenous bolus (relative to its safety profile as a 1-hour infusion. A selection criterion used to assess the usefulness and suitability of a (S)-1-phenyl-2-(pyridin) prodrug -2-yl)ethanamine was the potential for the prodrug to preserve the characteristics of oral iv infusion / 1 h of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine (eg, Tmax , Cmax, AUC), while blunting Cmax of the active component when the prodrug is administered directly into the bloodstream, thereby mitigating potential misuse (eg, abusive tendencies) and/or safety concerns triggered by Cmax As a means of identifying prodrugs with appropriate pharmacokinetic profiles in man, multi-behavioral, physiologically based pharmacokinetic (PBPK) models were constructed for both (S)-1-phenyl-2-(pyridin-2-yl)ethanamine and each prodrug under consideration. The PBPK models were validated using a set of known prodrugs, for which human PK data were available (see Malmborg J & Ploeger BA, J Pharmacol Toxicol Methods (2013) May-June 203-13, which is incorporated here by reference). The rate constants used in the model were based on in vitro stability studies (ie, human intestinal fluid, human blood, etc.) conducted with both prodrugs and (S)-1-phenyl-2-(pyridin-2- yl)ethanamine (exemplary values shown in Tables 1 and 2).

[00101] Table 3 shows key pharmacokinetic predictions for Example 5 - one of the DPPIV cleaved prodrugs. As exemplified in Table 3 Cmax exposure of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine is predicted to increase by >2x when a given oral dose form is crushed and illicitly supplied as an administration of i.v. bolus. In contrast, (S)-1-phenyl-2-(pyridin-2-yl)ethanamine released from an orally administered prodrug has a PK profile similar to a 1-h infusion of (S)-1 -phenyl-2-(pyridin-2-yl)ethanamine without Cmax doubling when given as an i.v. cake. Also, because conversion to (S)-1-phenyl-2-(pyridin-2-yl)ethanamine is selectively triggered by DPPIV, a DPPIV inhibitor can be used to stop the conversion in case of deliberate or inadvertent misuse - an added safety feature built into the DPPIV prodrug design.

[00102] In Table 3 Compound 1 is (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. In Table 3, all doses are selected to contain equivalent amounts of Compound 1 [(S)-1-phenyl-2-(pyridin-2-yl)ethanamine free base], i.e., each dose contains the same amount of Compound 1. Compound 1 within it and potentially available for release in free base form ((S)-1-phenyl-2-(pyridin-2-yl)ethanamine. Thus, modeled Cmax concentrations of free base Compound 1 can be compared directly through different administrations of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine and (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrug, as shown in Table 3.Table 3

Example 16

[00103] This example illustrates that when prodrug doses of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine dihydrochloride (Example 5) and (S)-1-phenyl-2-( pyridin-2-yl)ethanamine dihydrochloride were administered to dogs, the risk of seizures, as represented by NOEL and LOEL, was lower with the prodrug.

[00104] (S)-1-phenyl-2-(pyridin-2-yl)ethanamine dihydrochloride and vehicle were administered once daily via oral gavage (water). Formulations were prepared twice, once weekly. Dosing formulations were stored and refrigerated (2-8°C) in amber glass containers until required for dosing. A range of concentrations of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine dihydrochloride in vehicle was prepared in order to maintain dose volume for all doses (1 mL/kg). Individual doses were based on the most recent body weights of dogs used in the study.

[00105] A prodrug of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine as fumarate salt (Example 5) and vehicle were administered once daily for 14 days via oral gavage at approximately the same time each day (± 1 hour), (vehicle is 0.3 M glyconic acid pH 3.0). A range of concentrations of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrug as fumarate salt in vehicle was prepared (e.g. 3, 10 and 30 mg/ml, of pro- (S)-1-phenyl-2-(pyridin-2-yl)ethanamine drug) in order to maintain dose volume for all doses (2 ml/kg). Dosage formulations were warmed to room temperature by stirring for at least 30 minutes prior to dosing and continuously throughout the administration procedure. Individual doses were based on the most recent body weights of dogs used in the study.

[00106] Compound 1 of Table 4 is (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. Table 4 illustrates the highest blood levels at which seizures did not occur (No Observed Effect Limit, NOEL) and the lowest blood levels at which seizures occur (Lowest Observed Effect Limit, LOEL) following administration of di- Compound 1 hydrochloride followed by administration of a Compound 1 fumarate salt prodrug. In each case, the highest blood concentration (Cmax) of (S)-1-phenyl-2-(pyridin) free base -2-yl)ethanamine is measured. In the first case, the free base (S)-1-phenyl-2-(pyridin-2-yl)ethanamine is generated directly from Compound 1, administered as the dihydrochloride salt. In the second case, (S)-1-phenyl-2-(pyridin-2-yl)ethanamine free base is generated via in vitro conversion of a prodrug of Compound 1, administered as the fumarate salt. The NOEL for seizures was higher when (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrug as the fumarate salt was administered compared to when (S)-1-phenyl- 2-(pyridin-2-yl)ethanamine as dihydrochloride salt was administered.Table 4

Example 17

[00107] This example illustrates that increasing the prodrug doses of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine, Example 5, produces less than proportional increases in concentration of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine in human intestinal fluid, as illustrated in Figure 1a and Figure 1b. As a consequence, it becomes more difficult to obtain high concentrations of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine by administering a prodrug of (S)-1-phenyl-2- (pyridin-2-yl)ethanamine relating to the administration of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine directly, which is sought after drug abuse. Without wishing to be bound by theory, the prodrugs of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine, where R1 is, are primarily cleaved by DPPIV. There is the potential for endogenous and/or exogenous modulation of DPPIV to impact the conversion of the prodrug to (S)-1-phenyl-2-(pyridin-2-yl)ethanamine dihydrochloride.

[00108] Prodrug stock solutions of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine (0.33, 1, 3 and 6 mmol/L) were prepared by adding a volume ( 8,25, 25, 75 and 150 μL) of 20 mmol/L prodrug solution of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine dissolved in DMSO, in FaSSIF-v2 (491 .75, 475, 425 and 350 µL). Subsequently, 10 μl of prodrug stock solution of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine was added to the supernatant (90 μL HIF) in a glass vial, mixed for 1 min, and injected into the LC-UV system. The initial concentration of the incubations were 33, 100, 300 and 600 μmol/L and samples were taken at 5, 20, 35, 65 and 125 min from the beginning of the incubation. An incubation experiment with (S)-1-phenyl-2-(pyridin-2-yl)ethanamine μmol/L was used as the standard sample (one-point calibration) to determine the formation rate and concentration of ( S)-1-phenyl-2-(pyridin-2-yl)ethanamine. Analysis was performed on a photodiode formation detector (analytical wavelength used was 261 nm) coupled to a Waters Acquiry UPLC. The column used was a BEH C-18, 1.7 µm, 2.1 x 50 mm ID maintained at 40oC and using a 0.2 µm in-line pre-filter. The mobile phases used consisted of A: 0.03% TFA in H2O (v/v) and B: 0.03 TFA in acetonitrile (v/v). Exemplary gradient: Initial 1% B rose to 95% B over 7 min and then held at 95% B for 0.4 min at a flow rate of 0.6 mL/min. The conversion rate of the prodrug to (S)-1-phenyl-2-(pyridin-2-yl)ethanamine was determined by adjusting the measured prodrug and concentrations of (S)-1-phenyl-2 -(pyridin-2-yl)ethanamine versus time.

Example 18

[00109] Consistent with the in vitro observations of Example 17, in vivo studies (Example 18 below) in rats illustrate that Cmax exposures of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine as described above, increase less than proportionally in the transition between therapeutic and supratherapeutic doses of a (S)-1-phenyl-2-(pyridin-2-yl)ethanamine prodrug. The results of these in vivo studies are tabulated in Table 5.

[00110] 52 male rats and 52 female rats were each administered (a) prodrug of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine as a fumarate salt in vehicle (0, 3M Glyconic Acid, pH 3.0) or (b) vehicle (0.3M Glyconic Acid, pH 3.0) once daily for 14 days at approximately the same time each day (0.9:26 ± 124 minutes ). Doses (30, 100 and 300 mg/kg prodrug of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine) were administered in a dose volume of 10 ml/kg. After 14 days, blood samples were collected 24 hours post-dose via the lateral tail vein in restrained animals. Blood samples were collected using 50 µl neutral Sarstedt Minivette POCT capillary tubes. Blood was then transferred to pre-chilled tubes containing ice-cold sodium citrate, shaken 5-10 times by hand and frozen in dry ice within 10 seconds of collection. Whole blood samples were shipped frozen on dry ice to Covance Laboratories Inc. for analysis. Samples were analyzed for prodrug concentrations of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine and (S)-1-phenyl-2-(pyridin-2-yl)ethanamine. All analytical work was conducted by Covance Laboratories, Inc., Madison, Wisconsin using an LC/MS/MS analytical method developed and validated by that laboratory.

[00111] Table 5 illustrates toxicokinetic parameters following the administration of therapeutic and supra-therapeutic doses of the prodrug of (S)-1-phenyl-2-(pyridin-2-yl)ethanamine in rats. Table 5 Mean Toxicocimetric Parameters for (S)-1-phenyl-2-(pyridin-2-yl)ethanamine in Rats after Oral Administration of (S)-1-((S)-2-amino-3-methylbtanoyl) -N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxoxamide fumarate (Example 5) for 14 Days.

Claims (13)

1. Compound, characterized by the fact that it has formula (I): where R1 is AA is a natural amino acid linked by a peptide bond; or a pharmaceutically acceptable salt thereof. 2. Compound according to claim 1, characterized in that it is selected from the group consisting of: (S)-1-((S)-2,6-Diaminoexanoyl)-N-((S)-1-phenyl- 2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide; (S)-1-((S)-2-Amino-3-(1H-imidazol-4-yl)propanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl )pyrrolidine-2-carboxamide; 2-((S)-2-((S)-1-((S)-2-Amino-3-(4-hydroxyphenyl)propanoyl)pyrrolidine-2-carboxamide)-2-phenylethyl)pyridine; 2-((S)-2-((S)-1-((S)-2-Amino-3-(1H-indol-3-yl)propanoyl)pyrrolidine-2-carboxamido)-2-phenylethyl)pyridine ; (S)-1-((S)-2-Amino-3-phenylpropanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide; or, (S)-1-((S)-2-Amino-4-methylpentanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl)pyrrolidine-2-carboxamide; or a pharmaceutically acceptable salt of either thereof. 3. Compound, characterized by the fact that it is (S)-1-((S)-2-amino-3-methylbutanoyl)-N-((S)-1-phenyl-2-(pyridin-2-yl)ethyl )pyrrolidine-2-carboxamide or a pharmaceutically acceptable salt thereof. 4. Pharmaceutical composition, characterized in that it comprises a compound of formula (I) or a pharmaceutically acceptable salt thereof as defined in claims 1, 2 or 3, in association with a pharmaceutically acceptable adjuvant, diluent or carrier. 5. Use of a compound of formula (1) or a pharmaceutically acceptable salt thereof as defined in claim 1, 2 or 3, characterized in that it is for the manufacture of a drug for the treatment of depression. 6. Use of a compound of formula (I) or a pharmaceutically acceptable salt thereof as defined in claim 1, 2 or 3, characterized in that it is for the treatment of depression. 7. Use according to claim 5 or 6, characterized in that the depression disorder is major depressive disorder. 8. Use of a compound of formula (I) or a pharmaceutically acceptable salt thereof as defined in claim 1, 2 or 3, characterized in that it is in the manufacture of a medicine for the treatment of pain. 9. Use of a compound of formula (I) or a pharmaceutically acceptable salt thereof, as defined in claim 1, 2 or 3, characterized in that it is for the treatment of pain. 10. Use of a compound of formula (I) or a pharmaceutically acceptable salt thereof as defined in claim 1, 2 or 3, characterized in that it is in the manufacture of a drug for the treatment of Rett Syndrome, suicidal ideation, bipolar disorder, obsessive compulsive disorder, sarine gas poisoning, or status epilepticus. 11. Use of a compound of formula (I) or a pharmaceutically acceptable salt thereof as defined in claim 1, 2 or 3, characterized in that it is for the treatment of Rett Syndrome, suicidal ideation, bipolar disorder, compulsive disorder obsessive disorder, sarine gas poisoning or status epilepticus. 12. Compound, characterized in that it is 2-((S)-2-phenyl-2-((S)-pyrrolid-2-incarboxamido)ethyl)pyridine or a salt thereof 13. Compound, characterized in that it is 2-((S)-2-phenyl-2-((S)-pyrrolidin-2-iocarboxamido)ethyl)pyridinium dichloride