Pfizer’s PF 04937319 glucokinase activators for the treatment of Type 2 diabetes

PF 04937319
N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2-carboxamide
MW 432.43

MF C₂₂ H₂₀ N₆ O₄

CAS 1245603-92-2

2-​Pyrimidinecarboxamid​e, N,​N-​dimethyl-​5-​[[2-​methyl-​6-​[[(5-​methyl-​2-​pyrazinyl)​amino]​carbonyl]​-​4-​benzofuranyl]​oxy]​-

N,N-Dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)carbamoyl)-benzofuran-4- yloxy)pyrimidine-2-carboxamide

Pfizer Inc. clinical candidate currently in Phase 2 development.

CLINICAL TRIALS

A trial to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of single doses of PF-04937319 in subjects with type 2 diabetes mellitus (NCT01044537)

Multiple dose study of PF-04937319 in patients with type 2 diabetes (NCT01272804)

Phase 2 study to evaluate safety and efficacy of investigational drug – PF04937319 in patients with type 2 diabetes (NCT01475461)

SYNTHESIS

Glucokinase is a key regulator of glucose homeostasis and small molecule activators of this enzyme represent a promising opportunity for the treatment of Type 2 diabetes. Several glucokinase activators have advanced to clinical studies and demonstrated promising efficacy; however, many of these early candidates also revealed hypoglycemia as a key risk. In an effort to mitigate this hypoglycemia risk while maintaining the promising efficacy of this mechanism, we have investigated a series of substituted 2-methylbenzofurans as “partial activators” of the glucokinase enzyme leading to the identification of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2-carboxamide as an early development candidate.


Diabetes is a major public health concern because of its increasing prevalence and associated health risks. The disease is characterized by metabolic defects in the production and utilization of carbohydrates which result in the failure to maintain appropriate blood glucose levels. Two major forms of diabetes are recognized. Type I diabetes, or insulin-dependent diabetes mellitus (IDDM), is the result of an absolute deficiency of insulin. Type Il diabetes, or non-insulin dependent diabetes mellitus (NIDDM), often occurs with normal, or even elevated levels of insulin and appears to be the result of the inability of tissues and cells to respond appropriately to insulin. Aggressive control of NIDDM with medication is essential; otherwise it can progress into IDDM. As blood glucose increases, it is transported into pancreatic beta cells via a glucose transporter. Intracellular mammalian glucokinase (GK) senses the rise in glucose and activates cellular glycolysis, i.e. the conversion of glucose to glucose-6-phosphate, and subsequent insulin release. Glucokinase is found principally in pancreatic β-cells and liver parenchymal cells. Because transfer of glucose from the blood into muscle and fatty tissue is insulin dependent, diabetics lack the ability to utilize glucose adequately which leads to undesired accumulation of blood glucose (hyperglycemia). Chronic hyperglycemia leads to decreases in insulin secretion and contributes to increased insulin resistance. Glucokinase also acts as a sensor in hepatic parenchymal cells which induces glycogen synthesis, thus preventing the release of glucose into the blood. The GK processes are thus critical for the maintenance of whole body glucose homeostasis.
It is expected that an agent that activates cellular GK will facilitate glucose-dependent secretion from pancreatic beta cells, correct postprandial hyperglycemia, increase hepatic glucose utilization and potentially inhibit hepatic glucose release. Consequently, a GK activator may provide therapeutic treatment for NIDDM and associated complications, inter alia, hyperglycemia, dyslipidemia, insulin resistance syndrome, hyperinsulinemia, hypertension, and obesity. Several drugs in five major categories, each acting by different mechanisms, are available for treating hyperglycemia and subsequently, NIDDM (Moller, D. E., “New drug targets for Type 2 diabetes and the metabolic syndrome” Nature 414; 821 -827, (2001 )): (A) Insulin secretogogues, including sulphonyl-ureas (e.g., glipizide, glimepiride, glyburide) and meglitinides (e.g., nateglidine and repaglinide) enhance secretion of insulin by acting on the pancreatic beta-cells. While this therapy can decrease blood glucose level, it has limited efficacy and tolerability, causes weight gain and often induces hypoglycemia. (B) Biguanides (e.g., metformin) are thought to act primarily by decreasing hepatic glucose production. Biguanides often cause gastrointestinal disturbances and lactic acidosis, further limiting their use. (C) Inhibitors of alpha-glucosidase (e.g., acarbose) decrease intestinal glucose absorption. These agents often cause gastrointestinal disturbances. (D) Thiazolidinediones (e.g., pioglitazone, rosiglitazone) act on a specific receptor (peroxisome proliferator-activated receptor-gamma) in the liver, muscle and fat tissues. They regulate lipid metabolism subsequently enhancing the response of these tissues to the actions of insulin. Frequent use of these drugs may lead to weight gain and may induce edema and anemia. (E) Insulin is used in more severe cases, either alone or in combination with the above agents. Ideally, an effective new treatment for NIDDM would meet the following criteria: (a) it would not have significant side effects including induction of hypoglycemia; (b) it would not cause weight gain; (c) it would at least partially replace insulin by acting via mechanism(s) that are independent from the actions of insulin; (d) it would desirably be metabolically stable to allow less frequent usage; and (e) it would be usable in combination with tolerable amounts of any of the categories of drugs listed herein.
Substituted heteroaryls, particularly pyridones, have been implicated in mediating GK and may play a significant role in the treatment of NIDDM. For example, U.S. Patent publication No. 2006/0058353 and PCT publication No’s. WO2007/043638, WO2007/043638, and WO2007/117995 recite certain heterocyclic derivatives with utility for the treatment of diabetes. Although investigations are on-going, there still exists a need for a more effective and safe therapeutic treatment for diabetes, particularly NIDDM.

Designing glucokinase activators with reduced hypoglycemia risk: discovery of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2-carboxamide as a clinical candidate for the treatment of type 2 diabetes mellitus

Jeffrey A. Pfefferkorn,*^a   et al

*Corresponding authors

^aPfizer Worldwide Research & Development, Eastern Point Road, Groton
E-mail: jeffrey.a.pfefferkorn@pfizer.com
Tel: +860 686 3421

Med. Chem. Commun., 2011,2, 828-839

DOI: 10.1039/C1MD00116G

http://pubs.rsc.org/en/content/articlelanding/2011/md/c1md00116g/unauth#!divAbstract
http://www.rsc.org/suppdata/md/c1/c1md00116g/c1md00116g.pdf

Glucokinase is a key regulator of glucose homeostasis and small molecule activators of this enzyme represent a promising opportunity for the treatment of Type 2 diabetes. Several glucokinase activators have advanced to clinical studies and demonstrated promising efficacy; however, many of these early candidates also revealed hypoglycemia as a key risk. In an effort to mitigate this hypoglycemia risk while maintaining the promising efficacy of this mechanism, we have investigated a series of substituted 2-methylbenzofurans as “partial activators” of the glucokinase enzyme leading to the identification of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2-carboxamide as an early development candidate.

N,N-Dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)carbamoyl)-benzofuran-4- yloxy)pyrimidine-2-carboxamide (28). To a solution of the 5-methyl-2-aminopyrazine (38.9 g, 356 mmol) in dimethoxyethane (315 mL) in a 3-neck flask equipped with overhead stirring and a condenser at 0 o C was added Me2AlCl (1 M solution in hexanes) (715 mL). The mixture was warmed to room temperature and stirred for 1.5 h. In a separate flask, 26 (52.6 g, 142.5 mmol) was dissolved in dimethoxyethane (210 mL). This mixture was then added to the amine mixture. A gum precipitated and upon scratching the flask it dissipated into a solid. The reaction was refluxed for 3.5 h. Aq. Rochelle’s salt (5 L) and 2-MeTHF (2 L) was added to the mixture and this was allowed to stir with overhead stirring for 14 h, after which time, a yellow solid precipitated. The solid was collected by filtration, washing with 2-MeTHF. The resulting solid was dried in a vacuum oven overnight to afford the desired material (50.0g) in 81% yield.
1 H NMR (400MHz, CDCl3) δ 9.54 (d, J = 1.56 Hz, 1H), 8.50 (s, 2H), 8.37 (s, 1H), 8.14 (d, J = 0.78 Hz, 1H), 7.88 – 7.92 (m, 1H), 7.52 (d, J = 1.37 Hz, 1H), 6.28 (t, J = 0.98 Hz, 1H), 3.14 (s, 3H), 2.98 (s, 3H), 2.55 (s, 3H), 2.49 (d, J = 1.17 Hz, 3H);
MS(ES+ ): m/z 433.4 (M+1), MS(ES- ): m/z 431.3 (M-1).

PAPER

http://pubs.rsc.org/en/content/articlelanding/2013/md/c2md20317k#!divAbstract

PAPER
Bioorganic & Medicinal Chemistry Letters (2013), 23(16), 4571-4578
http://www.sciencedirect.com/science/article/pii/S0960894X13007452

Figure 1.

Glucokinase activators 1 and 2.

PATENT

Pfizer Inc.
WO 2010103437
https://www.google.co.in/patents/WO2010103437A1?cl=en
Scheme I outlines the general procedures one could use to provide compounds of the present invention having Formula (I).

Preparations of Starting Materials and Key Intermediates
Preparation of Intermediate (E)-3-(ethoxycarbonyl)-4-(5-methylfuran-2-yl)but- 3-enoic acid (I- 1a):

(Ma) To a vigorously stirred solution of 5-methyl-2-furaldehyde (264 ml_, 2650 mmol) and diethyl succinate (840 ml_, 5050 mmol) in ethanol (1.820 L) at room temperature was added sodium ethoxide (0.93 L of a 21 weight % solution in ethanol) in one portion. The reaction mixture was then heated at reflux for 13 hours. After cooling to room temperature, the mixture was concentrated in vacuo (all batches were combined at this point). The resulting residue was partitioned between ethyl acetate (1 L) and hydrochloric acid (1 L of a 2M aqueous solution). After separation, the aqueous layer was extracted with ethyl acetate (2 x 1 L). The combined organic extracts were then extracted with sodium hydrogen carbonate (2 x 1 L of a saturated aqueous solution). These aqueous extracts were combined and adjusted to pH 2 with hydrochloric acid (2M aqueous solution) then extracted with ethyl acetate (2 x 1 L). These organic extracts were combined and concentrated in vacuo to give desired (E)-3-(ethoxycarbonyl)-4-(5-methylfuran-2-yl)but-3-enoic acid (J₁ Ia: 34.34 g, 5%). The original organic extract was extracted with sodium hydroxide (2 L of a 2M aqueous solution). This aqueous extract was adjusted to pH 2 with hydrochloric acid (2M aqueous solution) then extracted with ethyl acetate (2 x 1 L). These organic extracts were combined and concentrated in vacuo to give additional desired materials (395.2 gram, 63%) as red liquid. ¹H NMR (CDCI₃, 300 MHz) δ ppm 7.48 (s, 1 H), 6.57 (d, 1 H), 6.09 (d, 1 H), 4.24 (q, 2H), 3.87 (s, 2H), 2.32 (s, 3H), 1.31 (t, 3H).
Preparation of Intermediate ethyl 4-acetoxy-2-methylbenzofuran-6- carboxylate (1-1 b):

(M b) To a vigorously stirred solution of (E)-3-(ethoxycarbonyl)-4-(5- methylfuran-2-yl)but-3-enoic acid (1-1 a: 326.6 g, 1 .371 mol) in acetic anhydride (1 .77 L, 18.72 mol) at room temperature was added sodium acetate (193 g, 2350 mmol) in one portion. The reaction mixture was then heated at reflux for 2.5 hours. After cooling to room temperature, the mixture was concentrated in vacuo (all batches were combined at this point). The resulting residue was suspended in dichloromethane (1 .5 L) and filtered, washing the solids with dichloromethane (3 x 500 ml_). The combined filtrate and washings were then washed with sodium hydrogencarbonate (2 x 1 L of a saturated aqueous solution) and brine (2 L), then concentrated in vacuo to give desired ethyl 4-acetoxy-2-methylbenzofuran-6-carboxylate (H b: 549.03 g, quantitative). ¹H NMR (CDCI₃, 300 MHz) δ ppm 8.00-7.99 (m, 1 H), 7.64 (d, 1 H), 6.32-6.32 (m, 1 H), 4.38 (q, 2H), 2.47 (d, 3H), 2.37 (s, 3H), 1 .39 (t, 3H).
Preparation of Intermediate ethyl 4-hydroxy-2-methylbenzofuran-6- carboxylate (1- 1 c):

(He) To a stirred solution of ethyl 4-acetoxy-2-methylbenzofuran-6- carboxylate (Hb: 549.03 g, 1 .37 mol) in ethanol (4.00 L) at room temperature was added potassium carbonate (266 g, 1 .92 mol) in one portion. The reaction mixture was then heated at 60⁰C for 3 hours. Potassium carbonate (100 g, 0.720 mol) was then added in one portion and the reaction mixture was heated at 60⁰C for a further 3 hours. After cooling to room temperature the mixture was diluted with dichloromethane (2 L) and the suspension filtered, washing the solids with dichloromethane (2 x 1 L) (all batches were combined at this point). The combined filtrate and washings were then washed with citric acid (2.5 L of a 1 M aqueous solution), then concentrated in vacuo and the resulting residue purified by dry flash chromatography (hexane then 2:1 hexane:ethyl acetate). All fractions containing the desired product were combined and concentrated in vacuo. The resulting residue, which solidified on standing, was slurried with cold toluene and filtered. The solids were then stirred with hot toluene and decolourising charcoal for 1 hour, followed by filtration of the hot mixture through a pad of celite. The filtrate was allowed to cool and the resulting precipitate isolated by filtration to give desired ethyl 4-hydroxy-2- methylbenzofuran-6-carboxylate (1-1 c: 360 g, 90%) as orange powder.
¹H NMR (CDCI₃, 300 MHz) δ ppm 7.73-7.73 (m, 1 H), 7.45 (d, 1 H), 6.51 -6.50 (m, 1 H), 5.85 (s, 1 H), 4.39 (q, 2H), 2.48 (d, 3H), 1.40 (t, 3H). LCMS (liquid chromatography mass spectrometry): m/z 221.06 (96.39 % purity).


Preparation of SM-25-bromo-N,N-dimethylpyrimidine-2-carboxamide (SM-
£1:

(SM-2) Oxalyl chloride (47.4g, 369mmol) was added to a suspension of 5-
Bromo-pyrimidine-2-carboxylic acid (5Og, 250mmol) in dichloromethane (821 ml) at room temperature followed by 1 -2 drop of dimethylformamide. The reaction mixture was stirred under nitrogen for 2 hours LCMS in methanol indicated the presence of the methyl ester and some acid. Dimethylformamide (0.2ml) was added to the reaction mixture. The acid dissolved after 30 minutess. LCMS showed corresponding methyl ester and no starting material peak was observed. The solvent was removed and dried in vacuo to afford the crude 5-Bromo-pyrimidine-2-carbonyl chloride (55g, 100%). The 5-Bromo-pyrimidine-2-carbonyl chloride (55g, 250mmol) was dissolved in tetrahydrofuran (828ml) and dimethyl-amine (2M solution in tetrahydrofuran) (373ml, 745mmol) was added portionwise at room temperature. The reaction was stirred at room temperature under nitrogen for 16 hours, after which time, LCMS indicated completion. The mixture was diluted with ethyl acetate (500ml) and washed with H₂O (500ml). The water layer was further extracted with CH₂CI₂ (5x500ml), all organics combined, and dried over magnesium sulfate. The filtrate was concentrated in vacuo and then suspended in methyl-/-butylether (650ml). The solution was then heated to reflux. The hot solution was allowed to cool overnight to afford pink crystals. The crystals were filtered and washed with cold methyl-t-butylether (100ml) the solid was dried in a vacuum oven at 55⁰C for 12 hourrs to afford the title compound 5-bromo-N,N-dimethylpyhmidine-2-carboxamide (SM-2: 44g, 77%) as a pink solid.
¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 2.94 (s, 3 H) 3.13 (s, 3 H) 8.85 (s, 2 H) m/z (M+1 ) = 232.
Preparation of Intermediate Ethyl 4-(2-(dimethylcarbamoyl)Dyrimidin-5- yloxy)-2-methylbenzofuran-6-carboxylate (l-2a):

A mixture of Cs₂CO₃ (62.1 g, 191 mmol), 5-bromo-N,N- dimethylpyrimidine-2-carboxamide (SM-2: 24g, 104mmol) and ethyl 4- hydroxy-2-methylbenzofuran-6-carboxylate (1-1 c: 2Og, 91 mmol); 1 ,10- phenanthroline (1.64g, 9.07mmol) and copper iodide (864mg, 4.54mmol) in dimethylformamide (200ml) was purged with N₂ gas and then heated to 90°C using a mechanical stirrer. The heterogeneous reaction mixture was stirred at this temperature for 18 hours. HPLC indicated near completion. The reaction mixture was cooled to 35⁰C and diluted with ethyl acetate (300ml). The mixture was filtered to remove any cesium carbonate. The filtrate was then partitioned between water (500ml) and ethyl acetate (500ml); however, no separation was observed. Concentrated HCL (20ml) was added to the mixture. When the aqueous phase was about pH1 , the phases separated. The organics were separated and the aqueous layer reextracted with ethyl acetate (2x500ml). All organics were combined and back extracted with water (200ml) and brine (500ml). The organics were separated and treated with activated charcoal (10g) and magnesium sulfate. The mixture was allowed to stir for 10 minutes and then filtered through a plug of celite to afford a crude yellow solution. The filter cake was washed with ethyl acetate (100 ml_). The organics were concentrated in vacuo to afford a crude solid this was dried under high vacuum for 4 days. The dry crude solid was triturated using methanol (80 ml_). The solids were dispersed into a fine light orange crystalline powder with a red liquor. The solids were isolated by filtration and rinsed with methanol (20 ml_). The solid was dried in the vacuum oven at 55⁰C for 12 hours to afford ethyl 4-(2- (dimethylcarbamoyl)pyrimidin-5-yloxy)-2-methylbenzofuran-6-carboxylate (J₁ 2a) as a yellow solid (18.2g, 54%)
¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 1.41 (t, J=7.12 Hz, 3 H) 2.50 (d, J=0.98 Hz, 3 H) 3.00 (s, 3 H) 3.17 (s, 3 H) 4.41 (d, J=7.22 Hz, 2 H) 6.29 (s, 1 H) 7.62 (d, J=1.17 Hz, 1 H) 8.06 (s, 1 H) 8.50 (s, 2 H). m/z (M+1 ) = 370.5
Preparation of Starting material 5-bromo-N-ethyl-N-methylpyrimidine-2- carboxamide (SM-3):

(SM-3) Oxalyl chloride (1 .45g, 1 1 .1 mmol) was added to a suspension of 5-
Bromo-pyrimidine-2-carboxylic acid (1 .5g, 7.4mmol) in dichloromethane (50ml) at room temperature followed by 1 -2 drop of dimethylformamide. The reaction mixture was stirred under nitrogen for 2 hours LCMS in methanol indicated the presence of the methyl ester and some acid. Dimethylformamide (0.2ml) was added to the reaction mixture and all of the acid dissolved after 30 minutes. LCMS showed corresponding methyl ester and no starting material peak was observed. The solvent was removed and dried in vacuo to afford the crude 5-Bromo-pyrimidine-2-carbonyl chloride (1 -6g). 5-Bromo-pyrinnidine-2-carbonyl chloride (1600mg, 7.225mnnol) was dissolved in dichloromethane (25ml) and triethylamine (4.03ml, 28.9mmol) was added followed by ethyl-methyl-amine (0.68 mL, 7.92 mmol). The reaction was stirred at room temperature under nitrogen for 16 ours, after which time, LCMS indicated completion. The mixture was diluted with dichloromethane (50ml) and washed with water (50ml) followed by 10% citric acid (50ml) and brine (50ml). The organic layer was separated and dried over MgSO4, the residue was filtered and the solvent was removed in vacuo to afford the title compound 5-bromo-N-ethyl-N-methylpyrimidine-2- carboxamide (SM-3): (1.4g, 79.4%) as a brown oil.
¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 1.08 – 1.31 (m, 3 H) 2.99 (d, J=79.05 Hz, 3 H) 3.19 (q, J=7.22 Hz, 1 H) 3.59 (q, J=7.22 Hz, 1 H) 8.84 (d, J=3.12 Hz, 2 H)
Example 2
Preparation of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2- yl)carbamoyl)-benzofuran-4-yloxy)Dyrimidine-2-carboxamide (2):

(2)
To a solution of the 5-methyl-2-aminopyrazine (38.9 g, 356 mmol) in dimethylether (315 ml_) in a 3-neck flask equipped with overhead stirring and a condensor at O⁰C was added Me2AICI (1 M solution in hexanes) (715 ml_). The mixture was warmed at room temperature and stirred for 1.5 hours. In a separate flask, ethyl 4-(2-(dimethylcarbamoyl)pyrimidin-5-yloxy)-2- methylbenzofuran-6-carboxylate (l-2a: 52.6g, 142.5mmol) was dissolved in dimethylether (210 ml_). This mixture was then added to the complexed amine. A gum precipitated upon scratching the flask and dissipated into a solid. The resultant reaction was refluxed for 3.5 hours HPLC indicated 93% complete. Five liters of Rochelles salt made up in water and 2 liters of 2- methyltetrahydrofuran was added to the mixture. The reaction mixture was then poured into the biphasic system. The mixture was allowed to stir with overhead stirring for 14 hours, after which time, a yellow solid precipitated. The solid was collected through filteration. The solid retained was washed with 2-methyltetrahydrofuran. The resultant solid was dried in vacuo oven overnight to afford the title compound N,N-dimethyl-5-(2-methyl-6-((5- methylpyrazin-2-yl)carbamoyl)benzofuran-4-yloxy)pyhmidine-2-carboxamide (2): (49.98g, 81 %)
1H NMR (400 MHz, CHLOROFORM-d) d ppm 2.49 (d, J=1 .17 Hz, 3H) 2.55 (s, 3H) 2.98 (s, 3 H) 3.14 (s, 3 H) 6.28 (t, J=0.98 Hz, 1 H) 7.52 (d, J=1 .37 Hz, 1 H) 7.88 – 7.92 (m, 1 H) 8.14 (d, J=0.78 Hz, 1 H) 8.37 (s, 1 H) 8.50 (s, 2 H) 9.54 (d, J=1 .56 Hz, 1 H).
m/z (M+1 ) = 433.4, m/z (M-1 )= 431 .5

REFERENCES

Beebe, D.A.; Ross, T.T.; Rolph, T.P.; Pfefferkorn, J.A.; Esler, W.P.
The glucokinase activator PF-04937319 improves glycemic control in combination with exercise without causing hypoglycemia in diabetic rats
74th Annu Meet Sci Sess Am Diabetes Assoc (ADA) (June 13-17, San Francisco) 2014, Abst 1113-P

Amin, N.B.; Aggarwal, N.; Pall, D.; Paragh, G.; Denney, W.S.; Le, V.; Riggs, M.; Calle, R.A.
Two dose-ranging studies with PF-04937319, a systemic partial activator of glucokinase, as add-on therapy to metformin in adults with type 2 diabetes
Diabetes Obes Metab 2015, 17(8): 751

Study to compare single dose of three modified release formulations of PF-04937319 with immediate release material-sparing-tablet (IR MST) formulation previously studied in adults with type 2 diabetes mellitus (NCT02206607)
OTHERS

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