# Patent

## Title
3,5-dichloro,4-(3,4-(cyclo-)alkoxyphenyl)- 2-carbonyloxy)ethyl)pyridine derivatives as PDE-4 inhibitors

## Abstract

The invention relates to novel 3,5-dichloro,4-(3,4-(cyclo-) alkoxyphenyl)-2-carbonyloxy)ethyl)pyridine compounds which are both inhibitors of the phosphodiesterase 4 (PDE4) enzyme and muscarinic M3 receptor antagonists, methods of preparing such compounds, compositions containing them and therapeutic use thereof.

## Background
FIELD OF THE INVENTION
The present invention relates to novel compounds which are both inhibitors of the phosphodiesterase 4 (PDE4) enzyme and muscarinic M3 receptor antagonists. More particularly, the invention relates to compounds of formula (I) as below described, methods of preparing such compounds, compositions containing them and therapeutic use thereof.
BACKGROUND OF THE INVENTION
Chronic obstructive pulmonary disease (COPD) is a respiratory disorder characterized by progressive, not fully reversible, airflow limitation associated with an abnormal pulmonary inflammatory response to noxious particles or gases.
For this reason, bronchial relaxation and inflammatory response suppression represent a mechanistic approach to the treatment of COPD that might improve symptoms such as dyspnea, wheezing, chest tightness, cough and mucus secretion, improve health status and reduce exacerbations.
Nowadays, the drug therapy options for COPD fall into 2 general classes: bronchodilators, (β2-adrenoceptor agonists, antimuscarinic agents and methylxanthines) and antiinflammatory agents (glucocorticosteroids and selective phosphodiesterase-4 (PDE4) inhibitors).
Bronchodilator drugs are the current mainstay of treatment for symptoms' relief.
As anticholinergic bronchodilators, the efficacy of muscarinic M3 antagonists is based on the fact that the major reversible component of airflow narrowing in COPD patients is the increase of acetylcholine (ACh) released to airway smooth muscle, by the bronchial postganglionic vagal efferent in some pathological conditions. Therefore, compounds that antagonize the action of ACh at muscarinic receptors are able to counteract the bronchoconstriction and thus improve lung function in these patients.
Muscarinic antagonists block the effects of ACh at muscarinic receptors. Currently, there are five known muscarinic receptor subtypes (M1-M5); human airway smooth muscle contains M1, M2 and M3 receptors. M1 receptors facilitate neurotransmission through parasympathetic ganglia and are weakly expressed on submucosal glands in human airways. The M2 receptors are located on the smooth-muscle fibers. Some studies have suggested a small role of M2 mediating the inhibition of airway smooth-muscle relaxation caused by adenylyl cyclase activation by compounds such as beta agonists. In addition, presynaptic M2 receptors are found on postganglionic parasympathetic nerves that project to airway smooth muscle and mucus-producing cells. These presynaptic M2 autoreceptors provide a negative feedback mechanism, which, when stimulated, inhibit further release of ACh. Postsynaptic M3 receptors are known to mediate both contraction of smooth muscle in the respiratory tract and mucus secretion, making them a major target for symptomatic relief of COPD. Consequently, in the airways, the major effects of muscarinic antagonists are bronchodilation and reduction of mucus secretion via blockage of ACh-induced effects in the parasympathetic nervous system.
Given the distribution of muscarinic receptors, systemically available agents that bind to muscarinic receptors outside of the respiratory tract have the potential to produce unwanted side effects such as tachycardia, dry mouth, urinary retention and constipation. Whereas dry mouth is the most common systemic anticholinergic side effect associated with the use of antimuscarinic antagonists as a result of the systemic blockade of M1 and M3 receptors the most potentially serious systemic effect is tachycardia, which results from the blockade of cardiac M2 receptors.
Inhaled anticholinergic antimuscarinic drugs approved for the treatment of COPD include ipratropium bromide (Atrovent®), oxitropium bromide (Oxivent®) and tiotropium bromide (Spiriva®). Both ipratropium and oxitropium are short-acting agents. In contrast, tiotropium bromide is the only long-acting antimuscarinic agent (LAMA) currently marketed for COPD, proved to be suitable for once-daily administration as a dry powder. Several others newer LAMAs are newly registered for the treatment of COPD, including aclidinium bromide and glycopyrrolate bromide, or are currently in phase III development, including umeclidinium.
Although bronchodilators are quite effective to improve symptoms, they do not address the underlying chronic inflammation or the changes in airway structure.
Standard treatment with glucocorticosteroids as antiinflammatory agents has demonstrated limited efficacy. However, among the antiinflammatory agents currently being developed, PDE4 inhibitors proved to be effective in attenuating the responses of various inflammatory cells, through their ability to elevate cAMP levels.
PDE4 is the predominant PDE expressed in neutrophils and T cells, suggesting that PDE4 inhibitors would be effective in controlling inflammation in COPD. Inhibition of PDE4 in inflammatory cells influences various specific responses, such as the production and/or release of pro-inflammatory mediators including cytokines and reactive oxygen species, with a well-documented efficacy in animal models mimicking certain aspects of asthma and COPD, as well as inflammatory bowel disease, atopic dermatitis, psoriasis and rheumatoid arthritis.
The selective PDE4 inhibitor, roflumilast (Daxas®) is an approved phosphodiesterase-4 inhibitor for the treatment of COPD associated with chronic bronchitis and a history of exacerbations. Roflumilast inhibits lung inflammation and emphysema in a smoking model of COPD in mice. In COPD patients, oral roflumilast given over 4 weeks significantly reduces the numbers of neutrophils (by 36%) and CXCL8 concentrations in sputum. In clinical trials roflumilast (500 mg once daily) given over 12 months improved lung function in COPD patients to a small extent but had little effect in reducing exacerbations or improving quality of life. More recently roflumilast has been shown to significantly improve FEV 1 (by approximately 50 mL) and reduce exacerbation (by about 15%) in patients with severe disease who have frequent exacerbations and mucus hypersecretion. Roflumilast provides clinical benefit when added to salmeterol or tiotropium and so may be used as an additional treatment in patients with severe disease.
However, the clinical utility of PDE4 inhibitors has so far been compromised by the occurrence of mechanism-associated side effects, including headache, nausea and emesis, which often limited the maximally tolerated dose. This problem could be overcome by inhaled delivery and designing compounds with a potentially more advantageous therapeutic window.
Since bronchial relaxation and inflammatory response suppression represent a mechanistic approach to the treatment of COPD, the combination of muscarinic M3 antagonism with selective PDE4 inhibition may lead to a new class of drugs, combining both bronchodilating and antiinflammatory properties in one molecule, which may open new perspectives in the management of COPD.
Our co-pending application n. PCT/EP2013/075520 and the present invention address the above mentioned need.
SUMMARY OF THE INVENTION
The present invention is directed to compounds acting both as inhibitors of the phosphodiesterase 4 (PDE4) enzyme and as muscarinic M3 receptor antagonists falling within the scope of formula (I) of our co-pending application n. PCT/EP2013/075520 but not disclosed therein. The invention is also directed to methods of preparing said compounds, compositions containing them and therapeutic use thereof.
In particular the invention is directed to compounds of formula (I),




R1 is hydrogen;
R2 is phenyl optionally substituted by a halogen atom selected from fluorine, and chlorine;
Z is a —(CH2)m— group wherein m is an integer ranging from 1 to 3;
L1 is selected from a bond and a group —(CH2)p— wherein p is 1;
R3 is hydrogen or a hydroxyl group;
R4 is selected from the group consisting of methyl, iso-propyl and cyclopropylmethyl;
R5 is selected from the group consisting of methyl and difluoromethyl;
A is a group represented by the formula (i):




their N-oxides on the pyridine ring, deuterated derivative wherein at least one hydrogen atom is substituted by corresponding atoms of deuterium, and pharmaceutically acceptable salts, and/or solvates thereof.
The term “pharmaceutically acceptable salts”, refers to derivatives of compounds of formula (I) or of their corresponding N-oxides on the pyridine ring wherein the parent compound is suitably modified by converting any of the free acid or basic group, if present, into the corresponding addition salt with any base or acid conventionally intended as being pharmaceutically acceptable.
Suitable examples of said salts may thus include mineral or organic acid addition salts of basic residues such as amino groups, as well as mineral or organic acid residues such as carboxylic groups.
Cations of inorganic bases which can be suitably used to prepare salts comprise ions of alkali or alkaline earth metals such as potassium, sodium, calcium or magnesium.
Those obtained by reacting the main compound, functioning as a base, with an inorganic or organic acid to form a salt comprise, for example, salts of hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, acetic acid, methane sulfonic acid, camphor sulfonic acid, oxalic acid, maleic acid, fumaric acid, succinic acid and citric acid.
The skilled persons will appreciate that many organic compounds can form complexes with solvents in which they are reacted or from which they are precipitated or crystallized. These complexes are known as “solvates”, which are also an object of the invention.
The invention also concerns polymorphs and crystalline forms of compounds of formula (I), of their N-oxides on the pyridine ring, pharmaceutically acceptable salts, or solvates thereof.
Hereinafter, compounds of formula (I), (I)′, (IA), (Ia), (Ib), (Ic) and (Id), corresponding N-oxides on the pyridine ring, enantiomers, diastereoisomers and mixtures thereof, their pharmaceutically acceptable salts and solvates, and polymorphs or crystalline forms thereof defined in any aspect of the invention (except intermediate compounds described in the chemical processes) are referred to as “compounds of the invention”.
The invention further comprises a process for the preparation of compounds of the invention.
The invention also provides pharmaceutical compositions of compounds of the invention either alone or in combination, in admixture with one or more pharmaceutically acceptable carriers.
In a further aspect the invention provides the use of the compounds of the invention as a medicament.
In one aspect the invention provides the use of the compounds of the invention for the manufacture of a medicament.
In particular the invention provides the use of the compounds of the invention for the prevention and/or treatment of any disease wherein an inhibition of PDE4 activity along with muscarinic M3 receptor antagonism is desirable.
In particular the compounds of the invention alone or combined with other active ingredients may be administered for the prevention and/or treatment of a disease the respiratory tract characterized by airway obstruction such as asthma and COPD. In one embodiment, the compounds of the invention may be administered for the prevention and/or treatment of COPD.
In a further aspect the present invention provides the use of compounds of the invention for the preparation of a medicament for the prevention and/or treatment of any disease wherein an inhibition of PDE4 activity along with muscarinic M3 receptor antagonism is desirable.
Moreover the present invention provides a method for prevention and/or treatment of any disease wherein an inhibition of PDE4 activity along with muscarinic M3 receptor antagonism is desirable, said method comprises administering to a patient in need of such treatment a therapeutically effective amount of a compound of the invention.
A further aspect of the invention provides a suitable inhalation device, comprising a pharmaceutical composition of a compound of the invention, which may be respectively selected from a single- or multi-dose dry powder inhaler, a pressurized metered dosed inhaler or a nebulizer and in particular a soft mist nebulizer.
A further aspect of the invention provides a kit comprising the pharmaceutical compositions of a compound of the invention either alone or in combination with one or more active ingredient and a device which may be a single- or multi-dose dry powder inhaler, a metered dose inhaler or a nebulizer.


DETAILED DESCRIPTION OF THE INVENTION
The invention is directed to a class of compounds acting both as inhibitors of the phosphodiesterase 4 (PDE4) enzyme and as muscarinic M3 receptor antagonists.
The present invention relates to derivatives of general formula (I), N-oxides on the pyridine ring, deuterated derivatives and pharmaceutically acceptable salts or solvates thereof,




wherein R1, R2, R3, R4, R5, A, L1 and Z are as above defined.

It will be apparent to those skilled in the art that compounds of general formula (I) at least contain one stereogenic center, namely represented by the carbon atom (1), and therefore exist as optical stereoisomers.
It will be apparent to the skilled person that compounds according to the invention have at least two stereogenic centers (carbon atoms (1) and (2)), thus they may accordingly exist at least as four diastereoisomers. Where the compounds according to the invention possess more than two stereogenic centers, they will exist as 2n diastereoisomers (wherein n here refers to the number of stereogenic centers). It is to be understood that all such isomers and mixtures thereof in any proportion are encompassed within the scope of the present invention.
In a preferred embodiment, the present invention is directed to compounds of formula (I)′, which are compounds of formula (I) as above defined where the absolute configuration of carbon (1) is that shown herebelow:




The absolute configuration for carbon (1) is assigned on the basis of Cahn-Ingold-Prelog nomenclature based on groups' priorities.
In one preferred embodiment, for compounds of formula (I), absolute configuration at carbon (1) is (S).
In one embodiment, when A is a group of formula (i) as above defined, compounds of formula (I) may exist as at least four diastereoisomers couples (Ia), (Ib), (Ic) and (Id) herebelow reported, which are comprised within the scope of the present invention; each couple of diastereoisomers (Ia), (Ib), (Ic), (Id) is constituted by a mixture of corresponding epimers at stereogenic centre identified as (2).







It will be apparent to the skilled person that compounds of formula (Ia), (Ib), (Ic), (Id) may be also obtained as single diastereoisomers wherein stereogenic centre at carbon atom identified as (2) is defined as R or S.
In one embodiment, compounds of formula (Ia) are provided as above reported, or single diastereoisomers thereof.
It is to be understood that all preferred groups or embodiments described herebelow and hereabove for compounds of formula (I) may be combined among each other and apply to compounds of formula (IA), (Ia), (Ib), (Ic), (Id) and (I)′ as well mutatis mutandis.
In a preferred embodiment, the invention provides compounds of formula (IA), which are N-oxides on the pyridine ring of compounds of formula (I), deuterated derivatives and pharmaceutically acceptable salts and solvates thereof:




wherein R1, R2, R3, R4, R5, A, L1 and Z are as above defined.

According to the present invention there is provided a compound selected from the group consisting of:

    [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
    [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl]3-[2-[[1-(2-fluorophenyl)-2-oxo-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate;
    [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl]3-[2-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate;
    [(3R)-quinuclidin-3-yl] 2-[[4-[2-[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethoxy]-2-oxo-ethyl]phenyl]methylamino]-2-(2-fluorophenyl)acetate;
    Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
    Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
    Single diastereoisomer of [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl] 2-hydroxy-3-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
    Single diastereoisomer of [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl] 2-hydroxy-3-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
    Single diastereoisomer of [(3R)-quinuclidin-3-yl]2-[[4-[2-[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethoxy]-2-oxo-ethyl]phenyl]methylamino]-2-(2-fluorophenyl)acetate;
    Single diastereoisomer of [(3R)-quinuclidin-3-yl]2-[[4-[2-[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethoxy]-2-oxo-ethyl]phenyl]methylamino]-2-(2-fluorophenyl)acetate;
    Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[2-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate;
    Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[2-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate;
    Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[3-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]propyl]benzoate; and
    Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[3-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]propyl]benzoate


and pharmaceutically acceptable salts and solvates thereof.
The sentence “single diastereoisomer” was reported near the chemical name of each compound isolated as single diastereoisomer whose absolute configuration at stereogenic center (2) (see general formula (I) below) was not determined.




In one aspect of the present invention, a process for the preparation of compounds of the invention is provided.
Processes of preparation described below and reported in the following Schemes should not be viewed as limiting the scope of the synthetic methods available for the preparation of the compounds of the invention.
Compounds of formula (I) may be prepared according to schemes and procedures described in the co-pending international application n. PCT/EP2013/075520.
N-oxides of compounds of formula (I), represented by the formula (IA), can be obtained according to general synthetic routes reported in Scheme A, or following slightly modified procedures that the skilled person can easily apply. Some intermediates described in the following Scheme A may also be commercially available.
In the following Schemes, for compounds of formula (II) to (XV), unless otherwise indicated, the groups R1, R2, R3, R4, R5, A, L1 and Z have the same meanings as described for compounds of formula (I) above. The group Y is part of the group Z above described for compounds of formula (I), and is a group —(CH2)m-1—, wherein m is an integer ranging from 1 to 3. The group X may be a leaving group such as I, Br or triflate (CF3SO3—).
In the Scheme A only compounds of formula (IA) are prepared starting from the pyridine N-oxides (V) described in the co-pending international application n. PCT/EP2013/075520. Any corresponding compound of formula (I) which are not N-oxides on the pyridine ring may be similarly obtained starting from the non-oxidized pyridines, analogues of compounds (V), described in the co-pending international application n. PCT/EP2013/075520.
In Scheme A herebelow reference is made to specific synthetic schemes which are better detailed in the following paragraphs.











Typical reaction conditions comprise reacting a compound of formula (III) with a compound of formula (II) in a suitable solvent, such as acetonitrile in the presence of an acid, such as acetic acid, and a reducing agent, such as NaB(OAc)3H, at an appropriate temperature, such as room (or ambient) temperature or 0° C. or 40° C.
Compounds of formula (III) may be prepared according to Scheme S2 below by reaction of a compound of formula (V) as below reported, with an appropriate compound of formula (IV) as below reported.




Typical reaction conditions comprise reacting a compound of formula (V) with a compound of formula (IV) in a suitable solvent, such as DCM or DMF in the presence of a coupling agent, such as EDC/DMAP or HATU, at an appropriate temperature, such as room (or ambient) temperature.
Compounds of formula IV may be prepared according to scheme S8.
Compounds of formula V were prepared as described in the co-pending international application n. PCT/EP2013/075520.
Compounds of formula (II) may be prepared according to Scheme S3 below by reaction of a compound of formula (VI) as below reported.




Typical reaction conditions comprise reacting a compound of formula (VI) with an acid such as HCl or TFA in a suitable solvent, such as dioxane or DCM at an appropriate temperature, such as room (or ambient) temperature or 0° C.
Compounds of formula (VI) may be prepared according to Scheme S4 below by reaction of a compound of formula (VIII) as below reported, with an appropriate compound of formula (VII).




Typical reaction conditions comprise reacting a compound of formula (VIII) with a compound of formula (VII) in a suitable solvent, such as THF or DMF in the presence of a coupling agent, such as DCC/HOBt or HATU, at an appropriate temperature, such as room (or ambient) temperature.
Compounds of formula (VIII) may be prepared according to Scheme S5 below by reaction of a compound of formula (IX) as below reported.




Typical reaction conditions comprise reacting a compound of formula (IX) with di-tert butyl dicarbonate in a suitable solvent, such as dioxane and water in the presence of sodium hydroxide at an appropriate temperature, such as room (or ambient) temperature or 0° C.




Typical reaction conditions comprise reacting a compound of formula (X) with an acid such as HCl in a suitable solvent, such as THF at an appropriate temperature, such as room (or ambient) temperature or 0° C. or 40° C.
Compounds of formula (X) may be prepared according to Scheme S7 below by reaction of a compound of formula (XI) as below reported.




Typical reaction conditions comprise reacting a compound of formula (XI) with a compound of formula (V) in a suitable solvent, such as DCM or DMF in the presence of a coupling agent, such as EDC/DMAP or HATU, at an appropriate temperature, such as room (or ambient) temperature.
Compounds of formula (IV) may be prepared according to Scheme S8 below by reaction of a compound of formula (XII) as below reported.




Typical reaction conditions comprise reacting a compound of formula (XII) with hexamethylenetetramine in a suitable solvent, such as ethanol and water, at an appropriate temperature, such as room (or ambient) temperature to 80° C.
Compounds of formula (III) may be prepared according to Scheme S9 below by reaction of a compound of formula (XIII) as below reported.




Typical reaction conditions comprise reacting a compound of formula (XIV) with a compound of formula (XIII) in a suitable solvent, such as DMF, in the presence of a base, such as sodium bicarbonate or potassium carbonate, and in the presence of a palladium catalyst, such as Pd(OAc)2, at an appropriate temperature, such as room (or ambient) temperature.
Compounds of formula (XIV) may be prepared according to Scheme S10 below by reaction of a compound of formula (XV) as below reported.




Typical reaction conditions comprise reacting a compound of formula (XV) with a compound of formula (V) in a suitable solvent, such as DCM or DMF in the presence of a coupling agent, such as EDC/DMAP or HATU, at an appropriate temperature, such as room (or ambient) temperature.
Compounds of formula (V) were prepared as described in the co-pending international application n. PCT/EP2013/075520.
The process described is particularly advantageous as it is susceptible of being properly modulated, through any proper variant known to the skilled person, so as to obtain any of the desired compounds of the invention. Such variants are a further object of the invention.
From all of the above, it should be clear to the skilled person that any of the described groups may be present as such or in any properly protected form.
In particular, functional groups present in the compounds of formula (II) to (XV) and which could generate unwanted side reactions and by-products, need to be properly protected before the alkylation, acylation, coupling, oxidation or sulfonylation takes place. Likewise, subsequent deprotection of those same protected groups may follow upon completion of the said reactions.
In the invention, unless otherwise indicated, the term “protecting group” designates a protective group adapted to preserve the function of the group it is bound to. Typically, protective groups are used to preserve amino, hydroxy, or carboxyl functions. Appropriate protecting groups may thus include, for example, benzyl, benzyloxycarbonyl, t-butoxycarbonyl, alkyl or benzyl esters or the like, which are well known [see, T. W. Green; Protective Groups in Organic Synthesis (Wiley, N.Y. 1999)].
Likewise, selective protection and deprotection of any of the said groups, for instance including carbonyl, hydroxy or amino groups, may be accomplished according to known methods.
The N-oxides on the 4-pyridinyl ring of the compounds of formula (I) and embodiments thereof may be prepared according to known methods. For instance they may be prepared by dissolving the compound of formula (I) or embodiments thereof in CH2Cl2 or CHCl3, then adding an oxidizing agent such as m-chloro perbenzoic acid (mCPBA) to the resulting solution. Other oxidizing agents which may be used are hydrogen peroxide, perbenzoic acid, peracetic acid or potassium peroxymonosulfate (also known as Oxone).
Alternatively, in particular for those compounds comprising functional groups sensitive to oxidation, the corresponding N-oxides are prepared by carrying out the oxidation step before further functional groups are introduced, for example on compounds of formula (XIII) as above reported.
Preferably, the process for preparation of compounds of formula (I) or embodiments thereof is performed starting from N-oxide on the pyridine ring of compound of formula (VIII), thus allowing the preparation of compound of formula (I) or embodiments thereof in the form of N-oxides on the pyridine ring.
Optional salification of the compounds of formula (I) or N-oxides on the pyridine ring thereof may be carried out by properly converting any of the free acidic or amino groups into the corresponding pharmaceutically acceptable salts. In this case too, the operative conditions being employed for the optional salification of the compounds of the invention are all within the ordinary knowledge of the skilled person.
From all of the above, it should be clear to the skilled person that the above process, comprehensive of any variant thereof for the preparation of suitable compounds of the invention, may be conveniently modified so that to adapt the reaction conditions to the specific needs, for instance by choosing appropriate condensing agents, solvents and protective groups, as the case may be.
The invention also provides pharmaceutical compositions of compounds of the invention in admixture with one or more pharmaceutically acceptable carriers, for example those described in Remington's Pharmaceutical Sciences Handbook, XVII Ed., Mack Pub., N.Y., U.S.A.
Administration of the compounds of the invention or may be accomplished according to patient needs, for example, orally, nasally, parenterally (subcutaneously, intravenously, intramuscularly, intrasternally and by infusion), by inhalation, rectally, vaginally, topically, locally, transdermally, and by ocular administration. Various solid oral dosage forms may be used for administering compounds of the invention including such solid forms as tablets, gelcaps, capsules, caplets, granules, lozenges and bulk powders. The compounds of the invention may be administered alone or combined with various pharmaceutically acceptable carriers, diluents (such as sucrose, mannitol, lactose, starches) and excipients known in the art, including but not limited to suspending agents, solubilizers, buffering agents, binders, disintegrants, preservatives, colorants, flavorants, lubricants and the like. Time release capsules, tablets and gels are also advantageous in administering the compounds of the present invention.
Various liquid oral dosage forms may also be used for administering compounds of the invention, including aqueous and non-aqueous solutions, emulsions, suspensions, syrups, and elixirs. Such dosage forms can also contain suitable inert diluents known in the art such as water and suitable excipients known in the art such as preservatives, wetting agents, sweeteners, flavorants, as well as agents for emulsifying and/or suspending the compounds of the invention. The compounds of the invention may be injected, for example, intravenously, in the form of an isotonic sterile solution. Other preparations are also possible.
Suppositories for rectal administration of the compounds of the invention may be prepared by mixing the compound with a suitable excipient such as cocoa butter, salicylates and polyethylene glycols.
Formulations for vaginal administration may be in the form of cream, gel, paste, foam, or spray formula containing, in addition to the active ingredient, such suitable carriers as are known in the art.
For topical administration the pharmaceutical composition may be in the form of creams, ointments, liniments, lotions, emulsions, suspensions, gels, solutions, pastes, powders, sprays, and drops suitable for administration to the skin, eye, ear or nose. Topical administration may also involve transdermal administration via means such as transdermal patches.
For the treatment of the diseases of the respiratory tract, the compounds according to the invention are preferably administered by inhalation.
Inhalable preparations include inhalable powders, propellant-containing metered aerosols or propellant-free inhalable formulations and may be administered through a suitable inhalation device which may be respectively selected from dry powder inhaler, pressurized metered dosed inhaler, or a nebulizer.
For administration as a dry powder, single- or multi-dose inhalers known from the prior art may be utilized. In that case the powder may be filled in gelatine, plastic or other capsules, cartridges or blister packs or in a reservoir.
A diluent or carrier, generally non-toxic and chemically inert to the compounds of the invention, e.g. lactose or any other additive suitable for improving the respirable fraction may be added to the powdered compounds of the invention.
Inhalation aerosols containing propellant gas such as hydrofluoroalkanes may contain the compounds of the invention either in solution or in dispersed form. The propellant-driven formulations may also contain other ingredients such as co-solvents, stabilizers and optionally other excipients.
The propellant-free inhalable formulations comprising the compounds of the invention may be in form of solutions or suspensions in an aqueous, alcoholic or hydroalcoholic medium and they may be delivered by jet or ultrasonic nebulizers known from the prior art or by soft-mist nebulizers such as Respimat®.
The compounds of the invention may be administered as the sole active agent or in combination with other pharmaceutical active ingredients including those currently used in the treatment of respiratory disorders, e.g. beta2-agonists, antimuscarinic agents, corticosteroids, mitogen-activated protein kinases (P38 MAP kinase) inhibitors, nuclear factor kappa-B kinase subunit beta (IKK2) inhibitors, human neutrophil elastase (HNE) inhibitors, phosphodiesterase 4 (PDE4) inhibitors, leukotriene modulators, non-steroidal anti-inflammatory agents (NSAIDs) and mucus regulators.
The invention also provides combinations of a compound of the invention with a β2-agonist selected from carmoterol, vilanterol (GSK-642444), indacaterol, milveterol, arformoterol, formoterol, salbutamol, levalbuterol, terbutaline, AZD-3199, olodaterol (BI-1744-CL), abediterol (LAS-100977), bambuterol, isoproterenol, procaterol, clenbuterol, reproterol, fenoterol and ASF-1020 and salts thereof.
The invention also provides combinations of a compound of the invention with a corticosteroid selected from fluticasone propionate, fluticasone furoate, mometasone furoate, beclometasone dipropionate, ciclesonide, budesonide, GSK 685698, GSK 870086.
The invention also provides combinations of a compound of the invention with an antimuscarinic agent selected from the group consisting of aclidinium, tiotropium, ipratropium, trospium, glycopyrronium and oxitropium salts.
The invention also provides combinations of a compound of the invention with a PDE4 inhibitor selected from AN-2728, AN-2898, CBS-3595, apremilast, ELB-353, KF-66490, K-34, LAS-37779, IBFB-211913, AWD-12-281, cipamfylline, cilomilast, roflumilast, BAY19-8004 and SCH-351591, AN-6415, indus-82010, TPI-PD3, ELB-353, CC-11050, GSK-256066, oglemilast, OX-914, tetomilast, MEM-1414 and RPL-554.
The invention also provides combinations of a compound of the invention with a P38 MAP kinase inhibitor selected from the group consisting of semapimod, talmapimod, pirfenidone, PH-797804, GSK-725, minokine and losmapimod and salts thereof.
In a preferred embodiment, the invention provides combinations of a compound of the invention with an IKK2 inhibitor.
The invention also provides combinations of a compound of the invention with a HNE inhibitor selected from AAT, ADC-7828, Aeriva, TAPI, AE-3763, KRP-109, AX-9657, POL-6014, AER-002, AGTC-0106, respriva, AZD-9668, zemaira, AAT IV, PGX-100, elafin, SPHD-400, prolastin C and prolastin inhaled.
The invention also provides combinations of a compound of the invention with a leukotriene modulator selected from montelukast, zafirlukast and pranlukast.
The invention also provides combinations of a compound of the invention with a NSAID selected from the group consisting of ibuprofen and ketoprofen.
The invention also provides combinations of a compound of the invention with a mucus regulator selected from the group consisting of INS-37217, diquafosol, sibenadet, CS-003, talnetant, DNK-333, MSI-1956 and gefitinib.
The dosages of the compounds of the invention depend upon a variety of factors including the particular disease to be treated, the severity of the symptoms, the route of administration, the frequency of the dosage interval, the particular compound utilized, the efficacy, toxicology profile, and pharmacokinetic profile of the compound.
Advantageously, the compounds of the invention may be administered for example, at a dosage comprised between 0.001 and 1000 mg/day, preferably between 0.1 and 500 mg/day.
When they are administered by inhalation route, the dosage is advantageously comprised between 0.01 and 20 mg/day, preferably between 0.1 and 10 mg/day.
Preferably, the compounds of the invention alone or combined with other active ingredients may be administered for the prevention and/or treatment of any obstructive respiratory disease such as asthma, chronic bronchitis and chronic obstructive pulmonary disease (COPD).
However the compounds of the invention may be administered for the prevention and/or treatment of any disease wherein PDE4 inhibition or M3 antagonism is required. Said disease include: allergic disease states such as atopic dermatitis, urticaria, allergic rhinitis, allergic conjunctivitis, vernal conjunctivitis, eosinophilic granuloma, psoriasis, inflammatory arthritis, rheumatoid arthritis, septic shock, ulcerative colitis, Crohn's disease, reperfusion injury of the myocardium and brain, chronic glomerulonephritis, endotoxic shock, cystic fibrosis, arterial restenosis, atherosclerosis, keratosis, rheumatoid spondylitis, osteoarthritis, pyresis, diabetes mellitus, pneumoconiosis, toxic and allergic contact eczema, atopic eczema, seborrheic eczema, lichen simplex, sunburn, pruritus in the anogenital area, alopecia areata, hypertrophic scars, discoid lupus erythematosus, systemic lupus erythematosus, follicular and wide-area pyodermias, endogenous and exogenous acne, acne rosacea, Behçet's disease, anaphylactoid purpura nephritis, inflammatory bowel disease, leukemia, multiple sclerosis, gastrointestinal diseases, autoimmune diseases and the like.
They also include neurological and psychiatric disorders such as Alzheimer's disease, multiple sclerosis, amylolaterosclerosis (ALS), multiple systems atrophy (MSA), schizophrenia, Parkinson's disease, Huntington's disease, Pick's disease, depression, stroke, and spinal cord injury.
The invention will now be further described by way of the following examples.
EXAMPLES
Abbreviations
DCC=N,N′-Dicyclohexylcarbodiimide; HOBt=Hydroxybenzotriazole; HATU=(Dimethylamino)-N,N-dimethyl(3H-[1,2,3]triazolo [4,5-b]pyridin-3-yloxy) methaniminium hexafluorophosphate; EDC=1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride; DMAP=4-dimethylaminopyridine; DMF=dimethylformamide; DMSO=dimethylsulfoxide; EtOAc=Ethyl acetate; RT=room temperature; THF=tetrahydrofuran; DCM=dichloromethane; MeOH=methyl alcohol; EtOH=ethylic alcohol; LHMDS=Lithium bis(trimethylsilyl)amide; m-CPBA=meta-Chloroperoxybenzoic acid; TFA=Trifluoroacetic acid; LC-MS=Liquid Chromatography/Mass Spectrometry; HPLC=high pressure liquid chromatography; MPLC=medium pressure liquid chromatography; SFC=Supercritical Fluid Chromatography
General Experimental Details
Analytical Methods
Liquid Chromatography-Mass Spectrometry
Method 1
LC-MS was performed on a Waters 2795 Alliance HT HPLC with Waters 2996 Diode Array Detector coupled to a Micromass ZQ, single quadrupole mass spectrometer using a Phenomenex Luna C18 (2) column (5 μm, 100×4.6 mm plus guard cartridge) with a linear gradient of 5-95% acetonitrile/water (with 0.1% formic acid in each mobile phase) within 3.5 minutes and held at 95% for 2.0 minutes.
Method 2
LC-MS was performed on a Waters 2795 Alliance HT HPLC with Waters 2996 Diode Array Detector coupled to a Micromass ZQ, single quadrupole mass spectrometer using a Waters Xterra MS C18 column (5 m, 100×4.6 mm plus guard cartridge) being initially held at 5% acetonitrile/water (with 10 mM ammonium bicarbonate in the aqueous mobile phase) for 0.5 minutes, followed by a linear gradient of 5-95% within 3.5 minutes and then held at 95% for 1.5 minutes.
NMR
1H Nuclear magnetic resonance (NMR) spectroscopy was carried out using a Bruker instrument operating at 400 MHz using the stated solvent at around room temperature unless otherwise stated. In all cases, NMR data were consistent with the proposed structures. Characteristic chemical shifts (6) are given in parts-per-million using conventional abbreviations for designation of major peaks: e.g. s, singlet; d, doublet; t, triplet; q, quartet; dd, doublet of doublets; dt, doublet of triplets; m, multiplet; br, broad.
Preparative Reverse-Phase HPLC Conditions
Preparative HPLC purification was performed by reverse phase HPLC using a Waters Fractionlynx preparative HPLC system (2525 pump, 2996/2998 UV/VIS detector, 2767 liquid handler) or an equivalent HPLC system such as a Gilson Trilution UV directed system. The Waters 2767 liquid handler acted as both auto-sampler and fraction collector.
The columns used for the preparative purification of the compounds were a Waters Sunfire OBD Phenomenex Luna Phenyl Hexyl or Waters Xbridge Phenyl at 10 μm 19×150 mm or Waters CSH Phenyl Hexyl, 19×150, 5 μm column.
Appropriate focused gradients were selected based on acetonitrile and methanol solvent systems under either acidic or basic conditions.
The modifiers used under acidic/basic conditions were formic acid or trifluoroacetic acid (0.1% V/V) and ammonium bicarbonate (10 mM) respectively.
The purification was controlled by Waters Fractionlynx software through monitoring at 210-400 nm, and triggered a threshold collection value at 260 nm and, when using the Fractionlynx, the presence of target molecular ion as observed under APi conditions. Collected fractions were analysed by LCMS (Waters Acquity systems with Waters SQD).
Compound Preparation
Where the preparation of starting materials is not described, these are commercially available, known in the literature, or readily obtainable by those skilled in the art using standard procedures. Where it is stated that compounds were prepared “analogously” or “similarly” to earlier examples or intermediates, it will be appreciated that the reaction time, number of equivalents of reagents and temperature can be modified for each specific reaction and that it may be necessary or desirable to employ different work-up or purification techniques.
Flash chromatography refers to silica gel chromatography and is carried out using an Isolera MPLC system (manufactured by Biotage); pre-packed silica gel cartridges (supplied by Biotage); or using conventional glass column chromatography.
In the procedures that follow, after each starting material, reference to a compound number may be provided. This is provided merely for assistance to the skilled chemist. The starting material may not necessarily have been prepared from the batch referred to.
Many of the Compounds described in the following Examples have been prepared from stereochemically pure starting materials, for example 95% enantiomeric excess (ee).
The stereochemistry of the compounds in the Examples, where indicated, has been assigned on the assumption that absolute configuration at resolved stereogenic centers of staring materials is maintained throughout any subsequent reaction conditions.
Compounds isolated as single diastereoisomers whose absolute configuration at stereogenic center (2) was not determined, are herebelow referred to as Single Diastereoisomers without mention in their chemical name of absolute configuration for the unknown stereogenic centre.




Diastereomeric Separation
The diastereomeric separation of compounds was achieved either by chiral High Performance Liquid Chromatography (HPLC) using a Gilson Trilution preparative HPLC system (322 pump, 155 UV/VIS, GX281 liquid handler and fraction collector) or by Supercritical Fluid Chromatography (SFC) using a Waters Thar Prep 100 preparative SFC system (P200 CO2 pump, 2545 modifier pump, 2998 UV/VIS detector, 2767 liquid handler with Stacked Injection Module). The Waters 2767 liquid handler acted as both auto-sampler and fraction collector.
Intermediate 1
[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-formylbenzoate




A solution of (1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethanol (compound I-1/L described in the international application PCT/EP2013/075520, prepared as detailed below) (0.280 g, 0.69 mmol), 4-formylbenzoic acid (0.108 g, 0.72 mmol), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (0.263 g, 1.37 mmol) and 4-(dimethylamino)pyridine (0.041 g, 0.34 mmol) in DCM (15 mL) was stirred at room temperature for 18 hours. The reaction mixture was partitioned between saturated aqueous NaHCO3 (20 mL) and DCM (10 mL) and filtered through a phase separator. The solvent was removed in vacuo and the crude material was purified by silica gel column chromatography eluting with 1:1 DCM:EtOAc to afford the title compound as a colourless gum (0.280 g, 76%).
LCMS (Method 2): [MH+]=540 at 4.04 min.
The following intermediates were synthesised via the same method to Intermediate 1, starting from compound I-1/A, described in the international application PCT/EP2013/075520, prepared as detailed below:













Intermediate



Structure
number
Analytical Data











Intermediate 2
1H NMR (400 MHz, CDCl3): δ 10.08 (s, 1 H), 8.54 (t, J = 1.7 Hz, 1 H), 8.27 (dt, J = 7.8, 1.5 Hz, 1 H), 8.14 (s, 2 H), 8.09 (dt, J = 7.7, 1.5 Hz, 1 H), 7.63 (t, J =  7.7 Hz, 1 H), 7.05 (dd, J = 8.2, 2.1 Hz, 1 H), 7.00 (d, J = 2.1 Hz, 1 H), 6.87 (d, J = 8.3 Hz, 1 H), 6.33 (dd, J =  9.7, 4.6 Hz, 1 H), 3.92 (s, 3 H), 3.88 (s, 3 H), 3.76 (dd, J = 14.0, 9.8 Hz, 1 H), 3.39 (dd, J = 14.0, 4.6 Hz, 1 H). LCMS (Method 1): [MH+] = 476 at 3.55 min.


 






Intermediate 3
1H NMR (400 MHz, CDCl3): δ 10.10 (s, 1 H), 8.18 (d, J = 8.0 Hz, 2 H), 8.13 (s, 2 H), 7.95 (d, J = 8.0 Hz, 2 H), 7.05- 6.99 (m, 2 H), 6.87 (d, J = 8.4 Hz, 1 H), 6.33 (dd, J = 4.4, 9.6 Hz, 1 H), 3.91 (s, 3 H), 3.88 (s, 3 H), 3.75 (dd, J = 9.6, 14.0 Hz, 1 H), 3.38 (dd, J = 4.4, 14.0 Hz, 1 H). LCMS (method 1): [MH+] = 476 at 3.65 min.









Intermediate 4
Preparation of (R)-quinuclidin-3-yl 2-((tert-butoxycarbonyl)amino)-2-phenylacetate




2-((tert-Butoxycarbonyl)amino)-2-phenylacetic acid (3.14 g, 12.51 mmol), (R)-quinuclidin-3-ol (1.91 g, 15.01 mmol), N,N′-Dicyclohexylcarbodiimide (3.10 g, 15.01 mmol) and 1-hydroxybenzotriazole hydrate (2.02 g, 15.01 mmol) where mixed together in THF (50 mL) and stirred at ambient temperature for 20 hours. After this time the reaction mixture was filtered through a pad of Celite® and concentrated in vacuo. The resulting crude was partitioned between ethyl acetate (50 mL) and 2M aqueous sodium carbonate solution (2×30 mL), the organic phase was washed with saturated sodium chloride solution (50 mL), separated and filtered through a phase separator and the solvent was removed in vacuo to give the title compound as a white foam (3.48 g, 77%) as a diastereoisomeric mixture.
1H NMR (400 MHz, DMSO) 7.78 (1H, d, J=8.1 Hz), 7.45-7.40 (2H, m), 7.40-7.30 (3H, m), 5.22-5.16 (1H, m), 4.73-4.64 (1H, m), 3.10-2.95 (1H, m), 2.66-2.52 (3H, m), 2.46-2.37 (1H, m), 2.21-2.12 (1H, m), 1.88† (1H, d, J=2.8 Hz), 1.75* (1H, s), 1.68-1.45 (2H, m), 1.40 (9H, d, J=26.6 Hz), 1.36-1.23 (2H, m); † and * refer to different isomers.
The following intermediates were synthesised via the same method to Intermediate 4, starting from the suitable acid:













Intermediate



Structure
number
Analytical Data











Intermediate 5
1H NMR (400 MHz, DMSO): δ 10.81 (br s, 1 H), 9.32 (br s, 3 H), 7.78-7.72 (m, 1 H), 7.62-7.55 (m, 1 H), 7.44-7.34 (m, 2 H), 5.52 (s, 1 H), 5.23-5.17 (m, 1 H), 3.66 (dd, J = 14.0, 8.5 Hz, 1 H), 3.32-3.10 (m, 5 H), 2.36-2.29 (m, 1 H), 2.12-2.00 (m, 1 H), 1.99-1.90 (m, 1 H), 1.90-1 79 (m, 1 H), 1.79-1.71 (m, 1 H). LCMS (Method 2): [MH+] = 279 at 2.59 min.









Intermediate 6
Preparation of [(3R)-quinuclidin-3-yl] 2-amino-2-phenyl-acetate hydrochloride salt




(R)-Quinuclidin-3-yl 2-((tert-butoxycarbonyl)amino)-2-phenylacetate (Intermediate 4) (3.48 g, 9.67 mmol) was added with 4M HCl in dioxane (12 mL, 48.3 mmol) and the reaction mixture was stirred at room temperature for 1 hour. The solvent was removed in vacuo co-evaporated with diethyl ether, dried in vacuo to afford the title compound as a white solid (3.10 g, quantitative yield).
1H NMR (400 MHz, DMSO): δ 10.56 (br s, 1H), 9.24 (br s, 3H), 7.65-7.59 (m, 2 H), 7.49-7.47 (m, 3H), 5.34 (s, 1H), 5.20-5.15 (m, 1H), 3.69-3.60 (m, 1H), 3.32-3.10 (m, 5H), 2.37-2.30 (m, 1H), 2.18-2.04 (m, 1H), 1.99-1.65 (m, 3H).
The following intermediates were synthesised via a similar method:













Intermediate



Structure
number
Analytical Data











Intermediate 7
1H NMR (400 MHz, DMSO): δ 10.81 (br s, 1 H), 9.32 (br s, 3 H), 7.78-7.72 (m, 1 H), 7.62-7.55 (m, 1 H), 7.44-7.34 (m, 2 H), 5.52 (s, 1 H), 5.23-5.17 (m, 1 H), 3.66 (dd, J = 14.0, 8.5 Hz, 1 H), 3.32-3.10 (m, 5 H), 2.36-2.29 (m, 1 H), 2.12-2.00 (m, 1 H), 1.99-1.90 (m, 1 H), 1.90-1 79 (m, 1 H), 1.79-1.71 (m, 1 H). LCMS (Method 2): [MH+] = 279 at




2.59 min.









Intermediate 1/A (I-1/A)
(S)-3,5-Dichloro-4-(2-(3,4-dimethoxyphenyl)-2-hydroxyethyl)pyridine 1-oxide




Step 1: Preparation of (R,S)-2-(3,5-dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethanol (I-1/Aa)
3,5-Dichloro-4-methylpyridine (54 g, 331 mmol) was dissolved in dry THF (480 mL) under Argon atmosphere and cooled at −78° C. in dry-ice/acetone bath. LHMDS 1N THF solution (331 mL, 331 mmol) was added drop-wise keeping the temperature at −78°. The mixture was stirred at −78° for 1 h. Thereafter, a solution of 3,4-dimethoxybenzaldehyde (50 g, 301 mmol) in dry THF (120 mL) was added drop-wise keeping the temperature at −78° C. When the addition was completed, the mixture was allowed to warm at RT.
The reaction was poured into ice and water (1 L) and the mixture was stirred until a copious precipitate formed. The solid was filtered, and dissolved in ethyl acetate (500 mL), dried over Na2SO4 and the solvent evaporated under vacuum. The crude was crystallized in CHCl3/Hexane. The precipitate was filtered, washed with hexane and dried under vacuum at 40° C. for 8 h to give 55 g of the title compound (45% yield). The mother liquor solution was evaporated under vacuum at 40° C., dissolved in ethyl acetate (200 mL) and extracted with 200 ml of water. The organic solution was dried over Na2SO4 and the solvent evaporated under vacuum at 40° C. The crude was crystallized in CHCl3/Hexane, and additional 15 g of the title product were obtained (70% overall yield).
Step 2: Preparation of (R,S)-2-(3,5-dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethyl (R)-2-(6-methoxynaphthalen-2-yl)propanoate (I-1/AB)
(R,S)-2-(3,5-dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethanol (50 g, 152 mmol), (R)-2-(6-methoxynaphthalen-2-yl)propanoic acid (38.6 g, 168 mmol), DMAP (20.5 g, 168 mmol) and EDC (43.8 g, 229 mmol) were dissolved in DMF (300 mL) and the reaction mixture was stirred at RT for 2 h. Thereafter, water (500 mL) was added, and the solution stirred till complete precipitation occurs. The solid was filtered and dissolved in DCM (500 mL). The organic solution was washed with aqueous HCl 1N (2×500 mL), saturated aqueous NaHCO3 solution (500 mL) and dried over Na2SO4. The solvent was evaporated under vacuum and the solid residue sonicated in EtOH (300 mL) and triturated for 1 h. The resulting precipitate was collected by filtration and dried under vacuum at 40° C. for 4 h to give 79 g (99% yield) of the title compound, as diastereoisomeric mixture.
Step 3: Preparation of (S)-2-(3,5-dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethyl) (R)-(2-(6-methoxynaphthalen-2-yl)propanoate (I-1/Ac)
(R,S)-2-(3,5-dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethyl) (R)-(6-methoxynaphthalen-2-yl)propanoate (diastereoisomeric mixture, 79 g, 146 mmol) was dissolved in CHCl3 (100 mL) and MeOH (30 mL) was slowly added up to persistent opalescence and the mixture left at RT for 2 h. The solid formed was collected by filtration and re-crystallized by CHCl3/MeOH (70 mL/20 mL) solvent system to obtain 35 g of the desired compound (yield 88%, ee 98%). Chiral HPLC analysis: Chiralcel OD column, 10 μm, 250×4.6 mm; Flow=0.8 ml/min; eluent=hexane:isopropanol 97/3; Rt=42.33 min;
1H NMR (600 MHz, CHLOROFORM-d) δ ppm 8.04 (s, 2H), 7.67 (d, J=8.79 Hz, 1H), 7.58 (d, J=8.52 Hz, 1H), 7.53 (m, 1H), 7.12-7.20 (m, 3H), 6.95 (dd, J=8.24, 1.92 Hz, 1H), 6.78-6.88 (m, 2H), 6.14 (dd, J=10.44, 4.12 Hz, 1H), 3.95 (s, 3H), 3.88 (s, 3H), 3.78-3.81 (m, 4H), 3.55 (dd, J=13.73, 10.44 Hz, 1H), 3.14 (dd, J=13.60, 4.26 Hz, 1H), 1.44 (d, J=7.14 Hz, 3H).
Step 4: Preparation of (S)-2-(3,5-dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethanol, (I-1/Ad)
(S)-2-(3,5-dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethyl) (R)-2-(6-methoxynaphthalen-2-yl)propanoate (30 g, 56 mmol) was dissolved in MeOH, and toluene was slowly added. Potassium tert-butoxide was slowly added to the suspension. The mixture was stirred for 24 h at RT. The reaction was diluted with water (500 mL) and the aqueous mixture was extracted with CHCl3 (500 mL). The organic layer was dried over Na2SO4 and the solvent was evaporated under vacuum. The residue was crystallized from CHCl3 (100 mL) and hexane (20 mL). The mother liquor was concentrated and recrystallized with an analogous procedure giving a second crop of desired compound. In total, 16 g of the title compound (87% yield) were obtained. Chiral HPLC analysis: Chiralcel OD column, 10 μm, 250×4.6 mm; flow=0.8 ml/mi eluent=hexane:isopropanol 95/5; Rt=58.03 min; [α]D20=+10.21 (c=0.506, Methanol); 1H NMR (400 MHz, acetone) 6 ppm 8.47 (s, 2H), 6.96-7.15 (m, 1H), 6.87 (m, 2H), 4.93-5.21 (m, 1H), 4.50 (d, J=3.97 Hz, 1H), 3.78 (s, 6H), 3.44 (dd, J=12.79, 8.38 Hz, 1H), 3.22 (dd, J=13.01, 5.51 Hz, 1H). MS/ESI+[MH]+: 328.19
Step 5: Preparation of (S)-3,5-dichloro-4-(2-(3,4-dimethoxyphenyl)-2-hydroxyethyl)pyridine 1-oxide (I-1/A)
(S)-2-(3,5-Dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethanol (4 g, 12 mmol) was dissolved in ethyl Acetate, and m-CPB acid was added to the solution. The mixture was stirred at RT for 5 h. The formed solid was collected by filtration, washed with ethyl acetate and dried under vacuum to give 1.72 g of (S)-2-(3,5-Dichloropyridin-4-yl)-1-(3,4-dimethoxyphenyl)ethanol (41% yield). Chiral HPLC analysis: Chiralcel OD column, 10 μm, 250×4.6 mm; Flow=0.8 ml/min; eluent=hexane:isopropanol 60/40; Rt=22.16 min; [α]D20=+68.91 (c=0.253, Methanol/CHCl3 1:1); 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 8.15 (s, 2H), 6.99 (m, 1H), 6.79-6.88 (m, 2H), 5.03 (dd, J=8.50, 5.32 Hz, 1H), 3.75-3.98 (m, 6H), 3.42 (dd, J=13.57, 8.56 Hz, 1H), 3.19 (dd, J=13.51, 5.32 Hz, 1H), 2.06-2.15 (m, 1H); MS/ESI+[MH]+: 344.19
Intermediates I-1/L
The intermediate I-1/L may be obtained following the procedure described above for intermediate 1/H, by reacting intermediate 1/I with a suitable alkylating agent.













Structure
Name
Intermediate
Analytical data











(S)-3,5-dichloro-4-(2-(4- (difluoromethoxy)-3- isopropoxyphenyl)-2- hydroxyethyl)pyridine oxide
I-1/L
1H NMR (400 MHz, DMSO-d6): δ ppm 8.52 (s, 2 H), 7.04- 7.13 (m, 2 H), 6.97 (t, J = 75.00 Hz, 1 H), 6.86 (dd, J = 7.94, 1.76 Hz, 1 H), 5.63 (d, J = 3.53





Hz, 1 H), 4.81-





4.90 (m, 1 H), 4.46-





4.65 (m, 1 H),





3.16 (d, J = 7.94 Hz,





1 H), 3.04 (d,





J = 6.17 Hz, 1 H),





1.26 (dd, J = 13.67,





6.17 Hz, 6 H)





MS/ESI+





[MH]+: 408









Intermediate 1/H (I-1/H)
(S)-3,5-dichloro-4-(2-(4-(difluoromethoxy)-3-methoxyphenyl)-2-hydroxyethyl)pyridine 1-oxide




Step 1: (S)-3,5-dichloro-4-(2-(4-(difluoromethoxy)-3-hydroxyphenyl)-2-hydroxyethyl)pyridine 1-oxide (I-1/I)
(S)-3,5-Dichloro-4-(2-(3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl)-2-hydroxyethyl)pyridine 1-oxide (5 g, 11.90 mmol) was added to 100 mL of 37% HCl and stirred at room temperature for about 3 min., obtaining a yellow solution. After stirring for further 3 min. the solution was poured into a solution of NaOH (48 g) in water (500 mL). The red solution was added with 1 M HCl to pH 1. The brown solid was filtered, washed with water and triturated with hot EtOH (50 mL). After stirring at r.t. for 1 h the solid was filtered, washed with EtOH and dried under vacuum at 40 C yielding 2.4 of the title compound. MS/ESI+[MH]+:366
Step 2: S)-3,5-dichloro-4-(2-(4-(difluoromethoxy)-3-methoxyphenyl)-2-hydroxyethyl)pyridine 1-oxide (I-1/H)
(S)-3,5-Dichloro-4-(2-(4-(difluoromethoxy)-3-hydroxyphenyl)-2-hydroxyethyl)pyridine 1-oxide (2 g, 5.46 mmol) was dissolved in DMF (16 mL) then K2CO3 (2 g, 14.47 mmol) and iodomethane (1.72 g, 12.12 mmol) were added and the mixture was stirred at r.t, for 4 h. The mixture was poured into 200 mL of water, filtered, washed with water and dried under vacuum at 40° C. 1.98 g of whitish solid was obtained.
1H NMR (400 MHz, DMSO-d6): δ ppm 8.53 (s, 2H), 7.08-7.13 (m, 2H), 7.01 (t, J=75.00 Hz, 1H), 6.88 (dd, J=7.94, 1.76 Hz, 1H), 5.64 (d, J=4.41 Hz, 1H), 4.77-4.94 (m, 1H), 3.81 (s, 3H), 3.17 (d, J=8.38 Hz, 1H), 3.05 (d, J=5.73 Hz, 1H) MS/ESI+[MH]+:380
Intermediate 1/G (I-1/G)
(S)-3,5-dichloro-4-(2-(3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl)-2-hydroxyethyl)pyridine 1-oxide




The intermediate I-1/G may be obtained following the procedure described in WO2010/089107.
Example 86 of PCT/EP2013/075520
[(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl] 2-hydroxy-3-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate formate salt
Step 1: Preparation of methyl 2-(benzyloxy)-3-formylbenzoate




A slurry of methyl 3-formyl-2-hydroxybenzoate (640 mg, 3.56 mmol), K2CO3 (982 mg, 7.12 mmol) and benzyl bromide (0.63 mL, 5.34 mmol) in DMF (3 mL) was stirred at room temperature for 16 h and diluted with EtOAc (100 mL) and water (40 mL). The layers were separated and the organic phase dried over MgSO4. After filtration and concentration in vacuo, the residue was purified via silica gel chromatography, eluting with 0-15% EtOAc in isohexane, to give the title compound as a white solid (598 mg, 62%).
1H NMR (400 MHz, CDCl3): δ 10.22 (s, 1H), 8.11 (dd, J=7.7, 1.9 Hz, 1H), 7.98 (dd, J=7.7, 1.9 Hz, 1H), 7.41-7.30 (m, 5H), 7.29-7.22 (m, 1H), 5.11 (s, 2H), 3.90 (s, 3H).
LCMS (Method 1): [MH+]=271 at 4.19 min.
Step 2: Preparation of [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)-phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl] 2-benzyloxy-3-formyl-benzoate




A solution of methyl 2-(benzyloxy)-3-formylbenzoate (598 mg, 2.21 mmol) in THF (4 mL) and MeOH (2 mL) and a solution of 4 N NaOH (1.10 mL, 4.43 mmol) was added at 0° C. and the reaction mixture stirred for 30 min. 2N HCl was then added at 0° C. to adjust the pH to  ̃2. After concentration in vacuo, the residue was azeotroped with toluene to dryness. The crude solid was dissolved in DMF (4.4 mL). To half of this solution (2.2 mL, 1.1 mmol) was added (S)-3,5-dichloro-4-(2-(3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl)-2-hydroxyethyl)pyridine 1-oxide (553 mg, 1.32 mmol), 4-(dimethylamino)-pyridine (67 mg, 0.55 mmol) and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (422 mg, 2.2 mmol and the resulting mixture was stirred at room temperature for 4 h. The reaction mixture was diluted with DCM (100 mL), the organic phase washed with sat. NaHCO3 (2×50 mL). The phases were separated over a hydrophobic frit and concentrated in vacuo. The residue was purified via silica gel chromatography, eluting with 0-100% EtOAc in isohexane to give the title compound as a white solid (784 mg, 54% over two steps).
1H NMR (400 MHz, CDCl3): δ 10.16 (s, 1H), 8.13 (s, 2H), 8.07 (dd, J=7.9, 1.6 Hz, 1H), 8.02-7.99 (m, 2H), 7.35-7.28 (m, 3H), 7.26-7.21 (m, 2H), 7.15 (d, J=8.4 Hz, 1H), 7.05-6.99 (m, 2H), 6.60 (t, J=75.3 Hz, 1H), 6.31 (dd, J=9.2, 5.0 Hz, 1H), 4.98-4.90 (m, 2H), 3.89-3.80 (m, 2H), 3.66 (dd, J=14.1, 9.2 Hz, 1H), 3.35 (dd, J=13.9, 5.1 Hz, 1H), 0.92-0.82 (m, 1H), 0.66-0.58 (m, 2H), 0.37-0.30 (m, 2H).
LCMS (Method 2): [MH+]=657 at 4.33 min.
Step 3: Preparation of [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)-phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl] 3-formyl-2-hydroxy-benzoate




TFA (0.4 mL) was carefully added to a solution of [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl] 2-benzyloxy-3-formyl-benzoate (116 mg, 0.18 mmol) in toluene (0.8 mL) at 0° C. The resulting mixture was stirred at 0° C. for 50 min. The solution was diluted with DCM (20 mL) and sat. NaHCO3 (20 mL). The layers were separated over a hydrophobic frit and the organic phase concentrated in vacuo, the residue azeotroped with toluene to dryness. The yellow gum (120 mg) was used in the next step without further purification.
1H NMR (400 MHz, CDCl3): δ 11.20 (s, 1H), 10.38 (s, 1H), 8.15 (s, 2H), 8.00 (d, J=7.4 Hz, 1H), 7.29-7.22 (m, 2H), 7.24-6.98 (m, 3H), 6.60 (t, J=75.3 Hz, 1H), 6.30 (dd, J=9.8, 4.3 Hz, 1H), 3.90 (d, J=7.0 Hz, 2H), 3.72 (dd, J=14.2, 9.9 Hz, 1H), 3.35 (dd, J=14.2, 4.3 Hz, 1H), 1.35-1.23 (m, 1H), 0.69-0.62 (m, 2H), 0.40-0.34 (m, 2H). LCMS (Method 2): [MH+]=568 at 4.08 min.
Step 4: Preparation of [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl] 2-hydroxy-3-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate formate salt




The title compound was synthesized from [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl] 3-formyl-2-hydroxy-benzoate and Intermediate 8 via the same method described for Example 1.
1H NMR (400 MHz, DMSO): δ 8.57 (s, 2H), 7.87 (d, J=8.0 Hz, 1H), 7.56 (d, J=7.4 Hz, 1H), 7.45-7.36 (m, 2H), 7.37-7.19 (m, 4H), 7.09 (dd, J=9.9, 0.4 Hz, 1H), 7.08 (t, J=75 Hz, 1H), 6.96 (t, J=7.7 Hz, 1H), 6.22 (dd, J=9.3, 4.5 Hz, 1H), 4.67-4.62 (m, 1H), 4.39 (d, J=7.1 Hz, 1H), 3.93 (d, J=6.9 Hz, 2H), 3.70-3.67 (m, 2H), 3.64 (dd, J=14.1, 9.5 Hz, 1H), 3.36 (dd, J=14.3, 5.0 Hz, 3H), 3.04 (dd, J=14.6, 8.2 Hz, 1H) †, 2.97 (dd, J=14.6, 8.2 Hz, 1H)*, 2.61-2.52 (m, 4H), 2.43 (d, J=15.7 Hz, 1H) †, 2.14 (d, J=14.7 Hz, 1H)*, 1.84-1.82 (m, 1H)*, 1.73-1.66 (m, 1H) †, 1.54-1.45 (m, 1H), 1.46-1.35 (m, 1H), 1.28-1.15 (m, 2H), 1.15-1.07 (m, 1H), 0.58-0.53 (m, 2H), 0.38-0.32 (m, 2H), † and * refer to different isomers.
LCMS (Method 1): [MH+]=812 at 2.72 min.
Example 87 of PCT/EP2013/075520
[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)-ethyl] 4-[2-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate formate salt




The title compound was obtained as a mixture of diastereoisomers following the procedure described in Example 32, starting from the appropriate amine.
1H NMR (400 MHz, CDCl3): δ 8.37 (s, 1H), 8.13 (s, 2H), 7.94 (dd, J=8.1, 2.1 Hz, 2H), 7.37-7.20 (m, 7H), 7.04-6.95 (m, 2H), 6.85 (d, J=8.2 Hz, 1H), 6.29 (dd, J=9.7, 4.6 Hz, 1H), 5.01-4.95 (m, 1H), 4.95-4.89 (m, 1H), 4.39 (s, 1H), 3.92-3.83 (m, 6H), 3.71 (dd, J=14.1, 9.7 Hz, 1H), 3.40-3.23 (m, 2H), 3.03-2.52 (m, 9H), 2.21 (s, 1H), 2.06 (s, 1H), 1.98-1.34 (m, 5H).
LCMS (Method 1): [MH+]=734 at 2.36 min.
N.B.: N-oxides Acohols and non N-oxides Alcohols are mentioned in the general schemes as described in the applicationPCT/EP2013/075520.
Example 1
[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate




A suspension of (R)-quinuclidin-3-yl 2-amino-2-phenylacetate bis hydrochloride salt (Intermediate 6 herein described) (0.189 g, 0.57 mmol) in EtOAc (10 mL) was added with Et3N (0.170 mL, 1.25 mmol). The reaction mixture was stirred at room temperature for 2 hours. The precipitate obtained was filtered, washed with EtOAc ( ̃5 mL) and the solvent was removed in vacuo. This residue was dissolved in CH3CN (10 mL) and to the solution was added [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-formylbenzoate (Intermediate 1 herein described) (0.280 g, 0.52 mmol) followed by acetic acid (0.030 mL, 0.52 mmol). The reaction mixture was stirred at room temperature for 20 hours. NaBH(OAc)3 (0.250 g, 1.18 mmol) was added and the reaction mixture was stirred at room temperature for a further 24 hours. The excess solvent was removed in vacuo and the residue was partitioned between EtOAc (50 mL) and saturated aqueous NaHCO3 solution (50 mL). The organic layer was washed with saturated brine (2×15 mL), separated and filtered through a phase separator and the solvent was removed in vacuo. Purification by preparative HPLC gave the title compound (1:1 mixture of diastereoisomers) as a light brown foam (0.209 g, 51%).
1H NMR (400 MHz, DMSO-d6): δ 8.57 (s, 2H); 7.95 (d, J=7.92 Hz, 2H); 7.47-7.24 (m, 7H); 7.32-6.90 (m, 4H); 6.20 (dd, J=9.20, 4.62 Hz, 1H); 4.73-4.62 (m, 2H); 4.35 (d, J=7.40 Hz, 1H); 3.74 (s, 2H); 3.61 (dd, J=14.21, 9.36 Hz, 1H); 3.01 (ddd, J=31.96, 14.62, 8.24 Hz, 1H); 2.62-2.53 (m, 3H); 2.53-2.11 (m, 2H); 1.78 (d, J=52.04 Hz, 1H); 1.60-1.40 (m, 2H); 1.05 (dd, J=24.46, 5.99 Hz, 8H).
LCMS (Method 1): [MH+]=784 at 2.77 min.
Example 2
[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 3-[2-[[1-(2-fluorophenyl)-2-oxo-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate
Step 1: Preparation of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 3-(1,3-dioxolan-2-ylmethyl)benzoate




A solution of 3-(1,3-dioxolan-2-ylmethyl)benzoic acid (500 mg, 2.4 mmol) and (1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethano 1 (compound I-1/A, described in the international application PCT/EP2013/075520) (826 mg, 2.4 mmol) in DCM (5 mL) was added with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (930 mg, 4.8 mmol) and 4-(dimethylamino)pyridine (147 mg, 1.2 mmol) and the mixture was stirred at room temperature for 18 hours. DCM (10 mL) and saturated aqueous sodium bicarbonate solution (10 mL) were added and the organic phase was passed through a hydrophobic frit and the solvent was removed in vacuo. The residue was purified by silica gel column chromatography eluting with 0-100% of 1:10 methanol:DCM in ethyl acetate to afford the title compound as a white solid (1.28 g, quant.).
1H NMR (400 MHz, CDCl3): 8.13 (s, 2H), 7.94 (s, 1H), 7.91 (d, J=7.8 Hz, 1H), 7.48 (d, J=7.7 Hz, 1H), 7.37 (t, J=7.7 Hz, 1H), 7.04-6.99 (m, 2H), 6.86 (d, J=8.2 Hz, 1H), 6.29 (dd, J=9.8, 4.5 Hz, 1H), 5.07 (t, J=4.6 Hz, 1H), 3.94-3.81 (m, 4H), 3.91 (s, 3H), 3.87 (s, 3H), 3.72 (dd, J=14.0, 9.8 Hz, 1H), 3.35 (dd, J=14.0, 4.6 Hz, 1H), 3.01 (d, J=4.6 Hz, 2H).
LCMS (Method 2): [MH+]=534 at 3.58 min.
Step 2: Preparation of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 3-(2-oxoethyl)benzoate




A solution of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 3-(1,3-dioxolan-2-ylmethyl)benzoate (134 mg, 1 mmol) in THF (18 mL) was added with 2 M aqueous hydrochloric acid solution (18 mL) and the mixture was heated to 40° C. for 5 hours. The solvent was removed in vacuo and the residue was purified by silica gel column chromatography eluting with 0-100% ethyl acetate in iso-hexane to afford the title compound as a yellow gum (492 mg, quant.).
1H NMR (400 MHz, CDCl3): 9.77 (t, J=2.0 Hz, 1H), 8.14 (s, 2H), 7.98 (d, J=7.3 Hz, 1H), 7.88 (s, 1H), 7.49-7.41 (m, 2H), 7.06-6.97 (m, 2H), 6.87 (d, J=8.2 Hz, 1H), 6.30 (dd, J=9.8, 4.5 Hz, 1H), 3.91 (s, 3H), 3.88 (s, 3H), 3.77 (d, J=2.0 Hz, 2H), 3.73 (dd, J=14.0, 9.8 Hz, 1H), 3.36 (dd, J=14.0, 4.5 Hz, 1H).
LCMS (Method 2): [MH+]=490 at 3.43 min.
Step 3: Preparation of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 3-[2-[[1-(2-fluorophenyl)-2-oxo-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate




A mixture of [(3R)-quinuclidin-3-yl] 2-amino-2-(2-fluorophenyl)acetate dihydrochloride (Intermediate 7 herein described) (193 mg, 0.55 mmol) and [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 3-(2-oxoethyl)benzoate (132 mg, 0.27 mmol) in ethanol (10 mL) was added with triethylamine (0.15 mL, 1.0 mmol) and acetic acid (0.03 mL, 0.55 mmol) and the mixture was stirred at room temperature for 10 minutes. Sodium cyanoborohydride (117 mg, 0.55 mmol) was added and the mixture was stirred at room temperature for 18 hours. The solvent was removed in vacuo and the residue was taken up in water (10 mL) and ethyl acetate (20 mL). The layers were separated and the aqueous phase was extracted with ethyl acetate (2×20 mL). The combined organic fractions were extracted with 0.2 M aqueous hydrochloric acid (40 mL) and water (30 mL). The aqueous extracts were combined and sodium chloride (6.5 g) was added. The mixture was extracted with chloroform (3×30 mL) and the combined organic extracts were passed through a hydrophobic frit and the solvent was removed in vacuo. Purification of the crude material by preparative HPLC afforded the title compound as an off-white solid (25 mg, 12%). 1H NMR (400 MHz, CD3CN): δ 8.16 (d, J=1.8 Hz, 2H), 7.92-7.85 (m, 2H), 7.49-7.27 (m, 4H), 7.18-7.01 (m, 4H), 6.93 (d, J=8.3 Hz, 1H), 6.22 (dd, J=4.5, 9.6 Hz, 1H), 4.78-4.70 (m, 1H), 4.70 (d, J=3.2 Hz, 1H), 3.82 (s, 3H), 3.81 (s, 3H), 3.69 (dd, J=9.6, 14.1 Hz, 1H), 3.35 (dd, J=4.5, 14.1 Hz, 1H), 3.12-2.98 (m, 1H), 2.94-2.19 (m, 9H), 1.88-1.69 (m, 1H), 1.64-1.07 (m, 4H). LCMS (Method 1): [MH+]=752 at 2.44 min.
The following Example was synthesised via a similar method to that used for Example 2, starting from Intermediate 6, herein described












Structure
Example
Analytical Data







[(1S)-2-(3,5-dichloro-1-oxido- pyridin-1-ium-4-yl)-1-(3,4- dimethoxyphenyl)ethyl]3-[2- [[2-oxo-1-phenyl-2-[(3R)- quinuclidin-3-yl]oxy- ethyl]amino]ethyl]benzoate   



Example 3
1H NMR (400 MHz, CD3CN): δ 8.15 (d, J = 2.3 Hz, 2 H), 7.92-7.85 (m, 2 H), 7.49-7.26 (m, 7 H), 7.09- 7.01 (m, 2 H), 6.92 (d, J = 8.1 Hz, 1 H), 6.22 (dd, J = 4.5, 9.6 Hz, 1 H), 4.75-4.66 (m, 1 H), 4.40 (s, 1 H), 3.81 (s, 3 H), 3.80 (s, 3 H), 3.69 (dd, J = 9.6, 14.1 Hz, 1 H), 3.35 (dd, J = 4.5, 13.9 Hz, 1 H), 3.12- 2.96 (m, 1 H), 2.90-2.19 (m, 9 H), 1.89-1.68 (m, 1 H), 1.64-1.06 (m, 4 H). Note: NH not visible. LCMS (Method 1): [MH+] = 734 at 2.39 min.









Example 4
[(3R)-quinuclidin-3-yl] 2-[[4-[2-[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethoxy]-2-oxo-ethyl]phenyl]methylamino]-2-(2-fluorophenyl)acetate
Step 1: Preparation of 2-(4-Formylphenyl)acetic acid




A solution of 2-[4-(bromomethyl)phenyl]acetic acid (770 mg, 3.36 mmol) in ethanol (6 mL) and water (6 mL) was added with hexamethylenetetramine (1.26 g, 9.0 mmol) and the mixture was heated to reflux for 4 hours. Concentrated HCl (1.5 mL) was added cautiously to the mixture at reflux. The mixture was heated to reflux for 30 minutes and then allowed to cool. Water (20 mL) and DCM (20 mL) were added and the organic phase was passed through a hydrophobic frit and the solvent was removed in vacuo to afford the title compound as an off-white solid (479 mg, 87%).
1H NMR (400 MHz, CDCl3): δ 10.01 (s, 1H), 7.86 (d, J=7.9 Hz, 2H), 7.47 (d, J=7.9 Hz, 2H), 3.75 (s, 2H). Note: OH not visible. LCMS (Method 1): [MH+]=165 at 2.80 min.
Step 2: Preparation of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 2-(4-formylphenyl)acetate




A solution of 2-(4-formylphenyl)acetic acid (1.97 g, 12 mmol) and (1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethanol (compound I-1/A described in the international application PCT/EP2013/075520) (4.13 g, 12 mmol) in DCM (40 mL) was added with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (1.97 g, 12 mmol) and 4-(dimethylamino)pyridine (734 mg, 6 mmol) and the mixture was stirred at room temperature for 24 hours. Saturated aqueous sodium bicarbonate solution (40 mL) was added and the organic phase was passed through a hydrophobic frit and the solvent was removed in vacuo. The residue was purified by silica gel column chromatography eluting with 0-10% methanol in DCM to afford the title compound as a yellow solid (385 mg, 7%).
1H NMR (400 MHz, CDCl3): δ 10.01 (s, 1H), 8.05 (s, 2H), 7.83 (d, J=8.1 Hz, 2H), 7.35 (d, J=8.1 Hz, 2H), 6.88-6.79 (m, 3H), 6.07 (dd, J=5.3, 9.7 Hz, 1H), 3.88 (s, 3H), 3.83 (s, 3H), 3.67 (d, J=4.0 Hz, 2H), 3.52 (dd, J=9.7, 14.0 Hz, 1H), 3.21 (dd, J=4.6, 14.3 Hz, 1H).
LCMS (Method 1): [MH+]=490 at 3.52 min.
Step 3: Preparation of [(3R)-quinuclidin-3-yl] 2-[[4-[2-[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethoxy]-2-oxo-ethyl]phenyl]methylamino]-2-(2-fluorophenyl)acetate




A mixture of [(3R)-quinuclidin-3-yl] 2-amino-2-(2-fluorophenyl)acetate dihydrochloride (Intermediate 7 herein described) (193 mg, 0.55 mmol) and [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 2-(4-formylphenyl)acetate (123 mg, 0.25 mmol) in ethanol (10 mL) was added with triethylamine (0.15 mL, 1.0 mmol) and acetic acid (0.03 mL, 0.55 mmol) and the mixture was stirred at room temperature for 30 minutes. Sodium cyanoborohydride (117 mg, 0.55 mmol) was added and the mixture was stirred at room temperature for 18 hours. The solvent was removed in vacuo and the residue was taken up in water (10 mL) and ethyl acetate (20 mL). The layers were separated and the organic phase was extracted with 0.2 M aqueous hydrochloric acid (40 mL) and water (30 mL). The aqueous extracts were combined and sodium chloride (6.5 g) was added. The mixture was extracted with chloroform (3×30 mL) and the combined organic extracts were passed through a hydrophobic frit and the solvent was removed in vacuo. Purification of the crude material by preparative HPLC afforded the title compound as an off-white solid (82 mg, 44%).
1H NMR (400 MHz, CD3CN): 8.10* (s, 2H), 8.09† (s, 2H), 7.57-7.50 (m, 1H), 7.42-7.33 (m, 1H), 7.28-7.20 (m, 3H), 7.19-7.10 (m, 3H), 6.91 (app s, 3H), 6.01 (ddd, J=2.0, 4.5, 9.9 Hz, 1H), 4.82-4.72 (m, 1H), 4.71 (s, 1H), 3.81 (s, 3H), 3.78 (s, 3H), 3.74 (s, 2H), 3.57 (dd, J=16.0, 22.2 Hz, 2H), 3.50 (dd, J=11.3, 14.9 Hz, 1H), 3.19 (dd, J=4.5, 13.9 Hz, 1H), 3.18-3.02 (m, 1H), 2.88-2.20 (m, 5H), 1.94-1.75 (m, 1H), 1.65-1.12 (m, 4H). * and † refer to different isomers.
LCMS (Method 1): [MH+]=752 at 2.43 min.
Example 5 and Example 6
Single diastereoisomers of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate (Ex. 5, diast 1 and Ex. 6, diast 2)




Purification of the 1:1 mixture of diastereoisomers of Example 1 by chiral preparative SFC afforded the single diastereoisomers. The absolute configurations of these were not determined.
Title compound (Example 5, single diastereoisomer 1) was obtained as a white solid (18 mg, 10%).
1H NMR (400 MHz, DMSO) δ 8.57 (s, 2H), 7.95 (d, J=8.3 Hz, 2H), 7.47 (d, J=8.1 Hz, 2H), 7.42 (d, J=7.1 Hz, 2H), 7.39-7.30 (m, 3H), 7.24-7.18 (m, 2H), 7.08 (dd, J=1.8, 8.3 Hz, 1H), 7.02 (t, J=73.6 Hz, 1H), 6.20 (dd, J=4.5, 9.3 Hz, 1H), 4.72-4.65 (m, 2H), 4.34 (d, J=3.8 Hz, 1H), 3.73 (s, 2H), 3.61 (dd, J=9.3, 13.9 Hz, 1H), 3.24-3.23 (m, 1H), 3.09-3.00 (m, 1H), 2.71-2.53 (m, 3H), 2.47-2.33 (m, 1H), 1.71 (dd, J=3.0, 3.0 Hz, 1H), 1.55-1.36 (m, 2H), 1.26 (dd, J=6.1, 24.5 Hz, 9H), 1.15-1.08 (m, 1H). LCMS (Method 1): [MH+]=784 at 2.77 min.
Title compound (Example 6, Single diastereoisomer 2) was obtained as a light brown solid (15.5 mg, 12%).
1H NMR (400 MHz, DMSO) δ 8.57 (s, 2H), 7.95 (d, J=8.1 Hz, 2H), 7.49-7.41 (m, 4H), 7.37 (dd, J=7.2, 7.2 Hz, 2H), 7.35-7.29 (m, 1H), 7.24-7.18 (m, 2H), 7.08 (dd, J=2.0, 8.3 Hz, 1H), 7.03 (t, J=74.9 Hz, 1H), 6.20 (dd, J=4.5, 9.3 Hz, 1H), 4.72-4.63 (m, 2H), 4.35 (s, 1H), 3.74 (s, 2H), 3.61 (dd, J=9.3, 14.1 Hz, 1H), 3.44 (d, J=20.0 Hz, 1H), 2.97 (ddd, J=1.8, 8.1, 14.6 Hz, 1H), 2.70-2.53 (m, 2H), 2.40-2.32 (m, 1H), 2.13 (d, J=33.2 Hz, 1H), 1.91-1.83 (m, 1H), 1.58-1.40 (m, 3H), 1.26 (dd, J=6.1, 24.5 Hz, 9H). LCMS (Method 1): [MH+]=784 at 2.78 min.
Compounds reported in the table herebelow were made according to the analogous procedures as that described in Example 5 and Example 6. Chiral preparative SFC or chiral preparative HPLC afforded the single diastereoisomers. Example 7 and Example 8 were obtained from the corresponding 1:1 diastereomeric mixture, described in the international application PCT/EP2013/075520 as Example 86 integrally reported below. Example 9 and Example 10 were obtained from the corresponding 1:1 diastereomeric mixture herein described as Example 6. Example 11 and Example 12 were obtained from the corresponding 1:1 diastereomeric mixture, described in the international application n. PCT/EP2013/075520 as Example 87, integrally reported below.












Structure
Reference
Analytical Data







[(1S)-1-[3- (cyclopropylmethoxy)-4- (difluoromethoxy)phenyl]-2- (3,5-dichloro-1-oxido-pyridin- 1-ium-4-yl)ethyl] 2-hydroxy- 3-[[[2-oxo-1-phenyl-2-[(3R)- quinuclidin-3-yl]oxy- ethyl]amino]methyl]benzoate   



Example 7 (Diastereomer 1)
1H NMR (400 MHz, CD3CN): δ 8.20 (s, 2 H), 7.99 (dd, J = 1.6, 8.0 Hz, 1 H), 7.54 (dd, J = 1.5, 7.3 Hz, 1 H), 7.45-7.32 (m, 5 H), 7.19 (d, J = 8.1 Hz, 2 H), 7.12-7.08 (m, 1 H), 6.96 (t, J = 7.9 Hz, 1 H), 6.79 (t, J = 75.4 Hz, 1 H), 6.26 (dd, J = 4.8, 9.3 Hz, 1 H), 4.73-4.67 (m, 1 H), 4.41 (s, 1 H), 3.94 (dd, J = 5.6, 9.1 Hz, 1 H), 3.90 (dd, J = 7.2, 7.2 Hz, 1 H), 3.80-3.66 (m, 3 H), 3.39 (dd, J = 4.7, 14.3 Hz, 1 H), 3.10-3.00 (m, 1 H), 2.72-2.62 (m, 3 H), 2.50-2.48 (m, 2 H), 1.94-1.87 (m, 1 H), 1.68- 1.60 (m, 2 H), 1.54-1.45 (m, 1 H), 1.40-1.20 (m, 2 H), 0.64-0.59 (m, 2 H), 0.39-0.34 (m, 2 H), OH and NH are not visible. LCMS (Method 1): [MH+] = 812 at 2.72 min


 


[(1S)-1-[3- (cyclopropylmethoxy)-4- (difluoromethoxy)phenyl]-2- (3,5-dichloro-1-oxido-pyridin- 1-ium-4-yl)ethyl]2-hydroxy- 3-[[[2-oxo-1-phenyl-2-[(3R)- quinuclidin-3-yl]oxy- ethyl]amino]methyl]benzoate   



Example 8 (Diastereomer 2)
1H NMR (400 MHz, CD3CN): δ 8.21 (s, 2 H), 8.00 (dd, J = 1.5, 8.1 Hz, 1 H), 7.54-7.51 (m, 1 H), 7.42- 7.31 (m, 5 H), 7.21-7.17 (m, 2 H), 7.10 (dd, J = 1.8, 8.3 Hz, 1 H), 6.96 (t, J = 7.4 Hz, 1 H), 6.79 (t, J = 75.5 Hz, 1 H), 6.26 (dd, J = 4.5, 9.3 Hz, 1 H), 4.74-4.70 (m, 1 H), 4.44-4.35 (m, 1 H), 3.95 (dd, J = 6.9, 6.9 Hz, 1 H), 3.90 (dd, J = 5.4, 8.3 Hz, 1 H), 3.82-3.66 (m, 4 H), 3.39 (dd, J = 4.7, 14.3 Hz, 1 H), 3.14-3.09 (m, 1 H), 2.78-2.72 (m, 4 H), 2.64-2.51 (m, 1 H), 1.85-1.77 (m, 1 H), 1.71-1.61 (n, 1 H), 1.53-1.50 (m, 1 H), 1.42- 1.35 (m, 1 H), 1.30-1.19 (m, 2 H), 0.65-0.59 (m, 2 H), 0.39-0.34 (m, 2 H), OH not visible. LCMS (Method 1): [MH+] = 812 at 2.71 min.


 


[(3R)-quinuclidin-3-yl] 2-[[4- [2-[(1S)-2-(3,5-dichloro-1- oxido-pyridin-1-ium-4-yl)-1- (3,4- dimethoxyphenyl)ethoxy]-2- oxo- ethyl]phenyl]methylamino]-2- (2-fluorophenyl)acetate   



Example 9 (Diastereomer 1)
1H NMR (400 MHz, CD3CN): δ 8.09 (s, 2 H), 7.54 (dt, J = 1.6, 7.5 Hz, 1 H), 7.41-7.33 (m, 1 H), 7.28- 7.19 (m, 3 H), 7.18-7.10 (m, 3 H), 6.91 (app s, 3 H), 6.02 (dd, J = 4.5, 9.9 Hz, 1 H), 4.82-4.76 (m, 1 H), 4.72 (s, 1 H), 3.81 (s, 3 H), 3.78 (s, 3 H), 3.75 (s, 2 H), 3.58 (dd, J =  15.1, 20.7 Hz, 2 H), 3.50 (dd, J =  9.7, 13.9 Hz, 1 H), 3.20 (dd, J = 4.7, 14.1 Hz, 1 H), 3.17-3.09 (m, 1 H), 2.75-2.55 (m, 5 H), 1.83-1.77 (m, 1 H), 1.65-1.44 (m, 2 H), 1.43-1.33 (m, 1 H), 1.26-1.16 (m, 1 H). LCMS (Method 1): [MH+] = 752 at 2.47 MM.


 


[(3R)-quinuclidin-3-yl] 2-[[4- [2-[(1S)-2-(3,5-dichloro-1- oxido-pyridin-1-ium-4-yl)-1- (3,4- dimethoxyphenyl)ethoxy]-2- oxo- ethyl]phenyl]methylamino]-2- (2-fluorophenyl)acetate   



Example 10 (Diastereomer 2)
1H NMR (400 MHz, CD3CN): δ 8.09 (s, 2 H), 7.54 (dt, J = 1.5, 7.6 Hz, 1 H), 7.42-7.35 (m, 1 H), 7.28- 7.22 (m, 3 H), 7.19-7.11 (m, 3 H), 6.91 (app s, 3 H), 6.02 (dd, J = 4.5, 10.1 Hz, 1 H), 4.79-4.74 (m, 1 H), 4.72 (s, 1 H), 3.81 (s, 3 H), 3.78 (s, 3 H), 3.75 (s, 2 H), 3.58 (dd, J =  14.8, 20.5 Hz, 2 H), 3.49 (dd, J =  10.1, 14.4 Hz, 1 H), 3.20 (dd, J =  4.7, 14.0 Hz, 1 H), 3.07 (ddd, J =  2.1, 8.1, 14.8 Hz, 1 H), 2.72-2.40 (m, 4 H), 2.32 (d, J = 14.6 Hz, 1 H), 1.94-1.89 (m, 1 H), 1.68-1.45 (m, 3 H), 1.35-1.25 (m, 1 H). LCMS (Method 1): [MH+] = 752 at 2.46 min.


 


[(1S)-2-(3,5-dichloro-1-oxido- pyridin-1-ium-4-yl)-1-(3,4- dimethoxyphenyl)ethyl] 4-[2- [[2-oxo-1-phenyl-2-[(3R)- quinuclidin-3-yl]oxy- ethyl]amino]ethyl]benzoate   



Example 11 (Diastereomer 
1H NMR (400 MHz, CD3CN): δ 8.18 (s, 2 H), 7.97 (d, J = 8.3 Hz, 2 1) H), 7.38-7.30 (m, 7 H), 7.10-7.03 (m, 2 H), 6.94 (d, J = 8.3 Hz, 1 H), 6.25 (dd, J = 4.5, 9.6 Hz, 1 H), 4.75- 4.70 (m, 1 H), 4.40 (s, 1 H), 3.83 (s, 3 H), 3.82 (s, 3 H), 3.71 (dd, J = 9.6, 14.1 Hz, 1 H), 3.36 (dd, J = 4.5, 14.1 Hz, 1 H), 3.14-3.06 (m, 1 H), 2.89-2.57 (m, 8 H), 2.52 (td, J = 2.6, 14.4 Hz, 1 H), 1.75-1.72 (m, 1 H), 1.62-1.42 (m, 2 H), 1.38-1.25 (m, 1 H), 1.20-1.10 (m, 1 H). LCMS (Method 2): [MH+] = 734 at 3.10


 


[(1S)-2-(3,5-dichloro-1-oxido- pyridin-1-ium-4-yl)-1-(3,4- dimethoxyphenyl)ethyl] 4-[2- [[2-oxo-1-phenyl-2-[(3R)- quinuclidin-3-yl]oxy- ethyl]amino]ethyl]benzoate   



Example 12 (Diastereomer 2)
1H NMR (400 MHz, CD3CN): δ 8.17 (s, 2 H), 7.97 (d, J = 8.3 Hz, 2 H), 7.40-7.27 (m, 7 H), 7.10-7.01 (m, 2 H), 6.93 (d, J = 8.3 Hz, 1 H), 6.24 (dd, J = 4.4, 9.5 Hz, 1 H), 4.74- 4.68 (m, 1 H), 4.40 (s, 1 H), 3.84 (s, 3 H), 3.82 (s, 3 H), 3.69 (dd, J = 9.6, 13.9 Hz, 1 H), 3.35 (dd, J = 4.5, 14.1 Hz, 1 H), 3.13-2.21 (m, 10 H), 1.92-1.85 (m, 1 H), 1.67-1.23 (m, 4 H). LCMS (Method 2): [MH+] =  734 at 3.11 min.









Example 13 and Example 14
Single diastereoisomers of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[3-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]propyl]benzoate (Ex. 13, diast 1 and Ex. 14, diast 2)
Step 1: Preparation of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-iodobenzoate




A solution of (S)-3,5-dichloro-4-(2-(3,4-dimethoxyphenyl)-2-hydroxyethyl)pyridine 1-oxide (compound I-1/A described in the co-pending international application n. PCT/EP2013/075520) (4.97 g, 14.5 mmol) in DCM (50 mL) was added with 4-iodobenzoic acid (3.00 g, 12.1 mmol), 4-(dimethylamino)-pyridine (744 mg, 6.1 mmol) and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (4.58 g, 24.2 mmol). The resulting solution was left to stir at room temperature for 18 hours. The reaction mixture was washed with saturated aqueous NaHCO3 (2×30 mL) and the organic phase was dried (MgSO4), filtered and concentrated in vacuo. The residue was purified by silica gel chromatography, eluting with 0-100% EtOAc in DCM to give the title compound as a white solid (5.61 g, 82% yield).
1H NMR (400 MHz, CDCl3): δ 8.12 (s, 2H), 7.83-7.78 (m, 2H), 7.74-7.70 (m, 2H), 7.01 (dd, J=1.9, 8.2 Hz, 1H), 6.96 (d, J=2.2 Hz, 1H), 6.86 (d, J=8.5 Hz, 1H), 6.29 (dd, J=4.4, 10.3 Hz, 1H), 3.90 (s, 3H), 3.88 (s, 3H), 3.70 (dd, J=9.8, 14.2 Hz, 1H), 3.35 (dd, J=4.4, 13.6 Hz, 1H). LCMS (Method 2): [MH+]=574 at 3.57 min
Step 2: Preparation of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-(3-oxopropyl)benzoate




A solution of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-iodobenzoate (5.61 g, 9.79 mmol), allyl alcohol (1.00 mL, 14.69 mmol), tetrabutyl ammonium bromide (3.16 g, 9.79 mmol), sodium bicarbonate (2.06 g, 24.48 mmol) and 4 Å molecular sieves (3.00 g) in DMF (50 mL) was degassed with N2 for 10 minutes. Palladium acetate (65 mg, 0.29 mmol) was then added and the resultant solution was stirred at room temperature under nitrogen atmosphere for 72 hours. The reaction mixture was filtered through a pad of Celite®, poured onto H2O (50 mL) and extracted with EtOAc (3×50 mL). The combined organic extracts were dried (Na2SO4) and concentrated in vacuo. The residue was purified by silica gel chromatography eluting with 0-100% EtOAc in iso-hexane to give [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-(3-oxopropyl)benzoate as a black oil (3.50 g, 71% yield).
1H NMR (400 MHz, CDCl3): δ 9.82 (t, J=1.1 Hz, 1H), 8.12 (s, 2H), 7.95 (d, J=8.1 Hz, 2H), 7.26 (d, J=8.6 Hz, 2H), 7.01 (dd, J=2.2, 8.0 Hz, 1H), 6.98 (d, J=2.4 Hz, 1H), 6.85 (d, J=8.1 Hz, 1H), 6.30 (dd, J=4.8, 9.8 Hz, 1H), 3.90 (s, 3H), 3.87 (s, 3H), 3.71 (dd, J=9.8, 13.6 Hz, 1H), 3.34 (dd, J=4.7, 13.8 Hz, 1H), 3.01 (t, J=7.6 Hz, 2H), 2.81 (t, J=7.3 Hz, 2H). LCMS (Method 2): [MH+]=504 at 2.86 min
Step 3: [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[3-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]propyl]benzoate




A solution of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-(3-oxopropyl)benzoate (500 mg, 0.99 mmol) in EtOH (50 mL) was added with [(3R)-quinuclidin-3-yl] 2-amino-2-phenyl-acetate hydrochloride salt (495 mg, 1.98 mmol), triethylamine (0.55 mL, 3.96 mmol), acetic acid (0.11 mL, 1.98 mmol) and the resultant mixture was stirred at room temperature for 10 minutes. Sodium cyanoborohydride (124 mg, 1.98 mmol) was added and the mixture was stirred at room temperature for 18 hours. The solvent was removed in vacuo and the residue taken up in H2O (20 mL) and EtOAc (20 mL). The layers were separated and the aqueous phase was extracted with EtOAc (2×20 mL). The combined organic phases were extracted with 0.2N aqueous hydrochloric acid (40 mL) and water (40 mL), sodium chloride (6.5 g) was added and the aqueous phase was extracted with chloroform (3×30 mL). The combined organic extracts were passed through a hydrophobic frit and the solvent was removed in vacuo. Purification of the crude material by preparative HPLC gave the diastereomeric mixture of the title compound as a light brown solid (200 mg, 27%).
1H NMR (400 MHz, CD3CN): δ 8.18 (s, 2H), 7.96 (d, J=8.3 Hz, 2H), 7.43-7.30 (m, 7H), 7.09 (d, J=2.8 Hz, 1H), 7.05 (dd, J=1.7, 8.0 Hz, 1H), 6.95 (d, J=8.3 Hz, 1H), 6.24 (dd, J=4.4, 9.6 Hz, 1H), 4.76-4.70 (m, 1H), 3.84 (s, 3H), 3.82 (s, 3H), 3.71 (dd, J=10.0, 15.3 Hz, 1H), 3.37 (dd, J=4.4, 13.7 Hz, 1H), 3.16-3.08† (m, 1H), 3.07-3.00* (m, 1H), 2.77-2.45 (m, 9H), 2.30-2.24 (m, 1H), 1.91-1.88 (m, 1H), 1.81 (t, J=7.4 Hz, 2H), 1.68-1.56 (m, 2H), 1.51-1.43 (m, 1H)†, 1.43-1.39* (m, 1H), 1.35-1.26 (m, 1H), 1.24-1.14 (m, 1H), † and * refer to different isomers. LCMS (Method 1): [MH+]=748 at 2.36 min.
Single diastereoisomers of the title compound were separated by preparative SFC to give:
Example 13 (Diastereomer 1)
1H NMR (400 MHz, DMSO): δ 8.60 (s, 2H), 7.93 (d, J=7.7 Hz, 2H), 7.47-7.43 (m, 2H), 7.42-7.31 (m, 5H), 7.11-7.00 (m, 3H), 6.26 (dd, J=4.0, 9.9 Hz, 1H), 4.75-4.69 (m, 1H), 4.41 (s, 1H), 3.83 (s, 3H), 3.80 (s, 3H), 3.68 (dd, J=9.0, 14.9 Hz, 1H), 3.42-3.36 (m, 2H), 3.14-3.07 (m, 1H), 2.73 (t, J=7.4 Hz, 2H), 2.68-2.58 (m, 5H), 2.52-2.43 (m, 2H), 1.79 (t, J=6.9 Hz, 2H), 1.75-1.71 (m, 1H), 1.58-1.40 (m, 2H), 1.38-1.29 (m, 1H), 1.19-1.11 (m, 1H). LCMS (Method 1): [MH+]=748 at 2.38 min.
Example 14 (Diastereomer 2)
1H NMR (400 MHz, DMSO): δ 8.61 (s, 2H), 7.93 (d, J=7.8 Hz, 2H), 7.47-7.44 (m, 2H), 7.42-7.31 (m, 5H), 7.11-7.01 (m, 3H), 6.26 (dd, J=4.8, 9.6 Hz, 1H), 4.72-4.67 (m, 1H), 4.41 (s, 1H), 3.83 (s, 3H), 3.80 (s, 3H), 3.68 (dd, J=9.1, 14.0 Hz, 1H), 3.38 (dd, J=4.7, 14.0 Hz, 1H), 3.05-2.97 (m, 1H), 2.73 (t, J=7.9 Hz, 2H), 2.68-2.58 (m, 3H), 2.54-2.37 (m, 4H), 2.18 (d, J=15.0 Hz, 1H), 1.91-1.86 (m, 1H), 1.80 (t, J=7.2 Hz, 2H), 1.64-1.53 (m, 2H), 1.52-1.43 (m, 1H), 1.33-1.22 (m, 1H). LCMS (Method 1): [MH+]=748 at 2.36 min.
Pharmacological Activity of the Compounds of the Invention
In Vitro Determination of PDE4 Inhibitory Activity
In vitro determination of PDE4 inhibitory activity for compounds of the invention may be determined according to one of the protocols herebelow reported:
PDE4B2 HTRF Assay:
PDE4B2 activity is detected using the LANCE Ultra cAMP homogeneous time resolved fluorescence resonance energy transfer (TR-FRET) assay from Perkin Elmer. The assay is based on the competition between the europium (Eu) chelate-labeled cAMP tracer and sample cAMP for binding sites on cAMP-specific monoclonal antibodies (mAb) labelled with the ULightTM dye. The assay is carried out in 384-well low volume plates in a volume of 10 μl. Human recombinant PDE4B2 (80 pM) is incubated for 2 h with 3 nM cAMP in buffer containing 1×HBSS, 5 mM HEPES, 3 mM MgCl2, 0.1% BSA, pH 7.4 with or without test compounds. The enzymatic reactions are efficiently stopped by the addition of 500 μM IBMX present in the combined Stop/Detection buffer containing europium (Eu) chelate-labeled cAMP tracer and cAMP-specific monoclonal antibodies (mAb) labelled with the ULightTM dye. Samples are then further incubated for 1 h before plates are read at ex 340 nm and em at 665 nm and 615 nm on an EnVision reader. IC50 values are determined from competition curves using a non-linear curve fitting program.
PDE4 Cell Free Assay Protocol
PDE4 activity is determined in U937 human monocytic supernatants cells lysate. Cells are cultured, harvested and supernatant fraction prepared essentially as described in Torphy T J et al J. Pharmacol. Exp. Ther. 1992; 263:1195-1205.
U937 cells are grown at 37° C., 5% CO2 in RPMI 1640 with GlutaMAXTM-I medium supplemented with 10% fetal bovine serum and 100 μg/mL Pen-strep (Gibco).
Cells are harvested and washed twice by centrifugation (150×g, 8 min) in cold PBS. Washed cells are re-suspended in cold Krebs-Ringer-Henseleit buffer at a final concentration 20×106 cells/mL and sonicated. After centrifugation at 15000×g for 20 min, the supernatants are pooled, divided in aliquots and stored at −80° C.
PDE4 activity is determined in cells supernatants by assaying cAMP disappearance from the incubation mixtures.
The concentration of the test compounds ranges between 10−12 M and 10−6 M. Reactions are stopped by enzyme heat inactivation (2.5 minutes at 100° C.) and residual cAMP content is determined using the ‘LANCE cAMP Assay’ from PerkinElmer following the provider instructions.
The results, expressed as mean±standard deviation of the molar concentration of the test compound producing 50% inhibition of cAMP disappearance (IC50).
Percentage of inhibition of PDE4 activity is calculated, assuming cAMP disappearance in the absence of inhibitors as 100% and cAMP disappearance in heat inactivated samples as 0%.
Representative compounds of the invention, when tested in one of the above reported protocols, displayed an IC50 lower than 100 nM.
In Vitro Determination of M3 Antagonism
In vitro determination of M3 antagonism for compounds of the invention may be determined according to one of the protocols herebelow reported:
M3 Receptor Radioligand Binding Assay:
Human M3 receptor membranes (15 μg/well) from Perkin Elmer are incubated with 0.52 nM Scopolamine Methyl Chloride, [N-methyl-3H] with or without test compounds, or a saturating concentration of Atropine (5 μM) for the determination of non-specific binding. The assay is carried out in 96-well polypropylene plates in a volume of 250 μl. The assay buffer used is 50 mM Tris-HCl, 154 mM NaCl (pH 7.4). The final assay concentration of DMSO is 0.5% (v/v). The plates are sealed and incubated for 2 h at room temperature on an orbital shaker (slow speed). Membranes are harvested onto 96-well unifilter GF/C filter plates pre-treated with 0.5% polyethyleneimine (v/v), using a filter manifold, washed four times with 200 μl of assay buffer. The plates are dried before addition of 50 μl of microscint-0, sealed then read in a Trilux Microbeta scintillation counter. IC50 values are determined from competition curves using a non-linear curve fitting program. Ki values are calculated from IC50 values by the Cheng and Prusoff equation.
M3 Binding Assay:
CHO-K1 clone cells expressing the human M3-receptor (Swissprot P20309) were harvested in Ca++/Mg++ free phosphate-buffered saline and collected by centrifugation at 1500 rpm for 3 min. The pellets were resuspended in ice cold buffer A (15 mM Tris-HCl pH 7.4, 2 mM MgCl2, 0.3 mM EDTA, 1 mM EGTA) and homogenized by a PBI politron (setting 5 for 15 s). The crude membrane fraction was collected by two consecutive centrifugation steps at 40000 g for 20 min at 4° C., separated by a washing step in buffer A. The pellets obtained were finally resuspended in buffer B (75 mM Tris HCl pH 7.4, 12.5 mM MgCl2, 0.3 mM EDTA, 1 mM EGTA, 250 mM sucrose), and aliquots were stored at −80° C.
The day of experiment, frozen membranes were resuspended in buffer C (50 mM Tris-HCl pH 7.4, 2.5 mM MgCl2, 1 mM EDTA). The non selective muscarinic radioligand [3H]-N-methyl scopolamine (Mol. Pharmacol. 45:899-907) was used to label the M3 binding sites. Binding experiments were performed in duplicate (ten point concentrations curves) in 96 well plates at radioligand concentration of 0.1-0.3 nM. The non specific binding was determined in the presence of cold N-methyl scopolamine 10 μM. Samples (final volume 0.75 mL) were incubated at room temperature for 90 min. The reaction was terminated by rapid filtration through GF/B Unifilter plates and two washes (0.75 mL) with cold buffer C using a Packard Filtermate Harvester. Radioactivity on the filters was measured by a microplate scintillation counter TriCarb 2500 (PerkinElmer).
Representative compounds of the invention, when tested in one of the above reported protocols, displayed an IC50 lower than 100 nM.
Representative compounds of the invention displayed an IC50 lower than 100 nM in both PDE4 cell free and M3 binding assays.

## Claims

1. A compound of general formula (I)



wherein:
R1 is hydrogen;
R2 is phenyl optionally substituted by a halogen atom selected from fluorine and chlorine;
Z is a —(CH2)m— group wherein m is an integer ranging from 1 to 3;
L1 is selected from a bond and a group —(CH2)p— wherein p is 1;
R3 is hydrogen or a hydroxyl group;
R4 is selected from the group consisting of methyl, iso-propyl and cyclopropylmethyl;
R5 is selected from the group consisting of methyl and difluoromethyl;
A is a group represented by the formula (i):





a N-oxide on the pyridine ring, a deuterated derivative or a pharmaceutically acceptable salt thereof.

2. A compound according to claim 1 which is a N-oxide represented by formula (IA)



wherein:
R1 is hydrogen;
R2 is phenyl optionally substituted by a halogen atom selected from fluorine and chlorine;
Z is a —(CH2)m— group wherein m is an integer ranging from 1 to 3;
L1 is selected from a bond and a group —(CH2)p— wherein p is 1;
R3 is hydrogen or a hydroxyl group;
R4 is selected from the group consisting of methyl, iso-propyl and cyclopropylmethyl;
R5 is selected from the group consisting of methyl and difluoromethyl;
A is a group represented by the formula (i):





a deuterated derivative or a pharmaceutically acceptable salt thereof.

3. A compound according to claim 2 which is selected from the group consisting of:
[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 3-[2-[[1-(2-fluorophenyl)-2-oxo-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate;
[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 3-[2-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate;
[(3R)-quinuclidin-3-yl] 2-[[4-[2-[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethoxy]-2-oxo-ethyl]phenyl]methylamino]-2-(2-fluorophenyl)acetate;
Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-[4-(difluoromethoxy)-3-isopropoxy-phenyl]ethyl] 4-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
Single diastereoisomer of [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl]2-hydroxy-3-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
Single diastereoisomer of [(1S)-1-[3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl]-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)ethyl]2-hydroxy-3-[[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]methyl]benzoate;
Single diastereoisomer of [(3R)-quinuclidin-3-yl]2-[[4-[2-[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethoxy]-2-oxo-ethyl]phenyl]methylamino]-2-(2-fluorophenyl)acetate;
Single diastereoisomer of [(3R)-quinuclidin-3-yl]2-[[4-[2-[(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethoxy]-2-oxo-ethyl]phenyl]methylamino]-2-(2-fluorophenyl)acetate;
Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[2-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate;
Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[2-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]ethyl]benzoate;
Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[3-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]propyl]benzoate; and
Single diastereoisomer of [(1S)-2-(3,5-dichloro-1-oxido-pyridin-1-ium-4-yl)-1-(3,4-dimethoxyphenyl)ethyl] 4-[3-[[2-oxo-1-phenyl-2-[(3R)-quinuclidin-3-yl]oxy-ethyl]amino]propyl]benzoate,
or a pharmaceutically acceptable salt thereof.

4. A pharmaceutical composition comprising a compound of claim 1, either alone or in combination with another active ingredient, in admixture with one or more pharmaceutically acceptable carrier.

5. A method of treating a disease of the respiratory tract characterized by airway obstruction, comprising administering the compound according to claim 1 to a subject in need thereof.

6. A method according to claim 5 wherein the disease of the respiratory tract is selected from asthma and COPD.

7. An inhalation device comprising a pharmaceutical composition according to claim 4.

8. A kit comprising the pharmaceutical composition of claim 4 and a device which may be a single- or multi-dose dry powder inhaler, a metered dose inhaler or a nebulizer.