|Title of Invention||
"NEW 4-BENZYLIDENE-PIPERIDIN DERIVATIVES"
|Abstract||The present invention relates to new 4-benzylidene-piperidin derivatives of formula (I), useful as NMDA, in a par- ticular NR2B subunit containing receptor antagonists and analgesica.|
|Full Text||The invention relates to new 4-benzylidene-piperidine derivatives which axe NR2B
selective NMDA receptor antagonists with improved in vivo profile or are intermediates for
Background of the invention.
N-methyl-D-aspartate (NMDA) receptors are ligand-gated cation-channels widely
expressed in the central nervous system. NMDA receptors are involved in developmental and
plastic changes of neurons. Overactivation of NMDA receptors by glutamate, their natural
ligand, can lead to calcium overload of cells. This triggers a cascade of intracellular events that
alters the cell function and ultimately may lead to death of neurones. Antagonists of the NMDA
receptors may be used for treating many disorders that are accompanied with excess release of
glutamate or overactivation of NMDA receptor for any reason [Curr Opin Ihvestig Drugs. 2003
• 4: 826-32].
The NMDA receptors are heteromeric assemblies built up from at least one NR1 subunit
together with one or more of the four NR2 subunits (NR2A-D). Both spatial distributions in the
CNS and the pharmacological sensitivity of NMDA receptors built up from various NR2
subunits are different. Particularly interesting of these is the NR2B subunit due to its restricted
distribution (highest densities in the forebrain and substantia gelatinosa of the spinal cord)
[Neuropharmacology, 38, 611-623 (1999)]. Compounds selective for this subtype are available
and have been proved to be effective in animal models of stroke [Stroke, 28, 2244-2251 (1997)],
traumatic brain injury [Brain Res., 792, 291-298 (1998)], Parkinson's disease [Exp. Neurol., 163,
239-243 (2000)], neuropathic and inflammatory pain [Neuropharmacology, 38,; 611-623 (1999)].
Moreover, NR2B subtype selective antagonists of NMDA receptors may provide'
therapeutic advantage over non-selective antagonists of NMDA receptors. The channel blocker
type non-selective NMDA antagonists phencyclidine and ketamine induce psychotomimetic
effects, hallucinations, dysphoria, catatonia and amnesia in man. These serious adverse effects
hinder their clinical use as potential medication. Compounds belonging to this class cause
behavioural abnormalities in animals, too, e.g. stimulate motor activity, induce' amnesia and
impair motor-coordination. The severity of these effects in animals is considered to be predictive
for the intensity of clinical side effects. NR2B subtype selective antagonists are expected to lack
most of these side effects. In animal behavioural studies some NR2B selective compounds [Ro
63-1908 in J. Pharmacol. Exp. Ther., 302 (2002) 940-948 and Ro 25-6981 in Behav. Pharmacol.,
14 (2003) 477-487] were reported to increase locomotor activity while no such effect was
observed with CP-101,606, another NR2B selective antagonist, and Ro 256981 by an other group
[Neuropharmacology, 38, 611-623 (1999)]. Lack of locomotor stimulating effect of CP-101,606
up to 56 mg/kg s.c. and 100 mg/kg i.p. was confirmed by others[Soc.Neurosc.Abs'tx. 21, 439.9.
1995.]. Thus, to our best knowledge, CP-101,606 is the only NR2B selective antagonist
consistently reported to lack locomotor stimulating effect. Since CP-101,606 appears to have
poor oral efficacy and according to published information was investigated only by intravenous
route of administration in humans, moreover it has polymorph CYP2D6 mediated metabolism
[Drug Metabolism and Disposition 31: 76-87], there remains to be a great need for new NR2B
antagonists with low side effect liability (high therapeutic index) good oral efficacy
(bioavailability) and good developability for therapeutic purposes, especially for oral treatment.
Saturated analogues of the compounds of the present invention are described in patent
No. WO 2003010159 as NR2B subtype selective NMDA antagonists. However, other close
structure analogues of the 4-benzylidene-piperidine derivatives of formula (I) are unknown in the
Summary of the invention
It was found that the new 4-benzylidene-piperidine derivatives of formula (I) of the
present' invention are functionally active NMDA antagonists selective for NR2B subunit
containing receptors. We also found that benzylidene-piperidines have in vivo analgesic potency
similar to that of their saturated benzyl-piperidine analogues. Surprisingly, while the latter
molecules cause locomotor stimulation at or slightly above their maximally effective analgesic
dose, compounds of the present invention are free from locomotor stimulatory effect up to 40-60-
fold analgesic doses. This feature may provide therapeutic advantage over NR2B selective
NMDA antagonists with lower therapeutic index.
Detailed description of the invention
The present invention relates therefore first to new 4-benzylidene-piperidin derivatives of
- wherein the meaning of
X and Y independently are hydrogen or halogen atom, hydroxy, cyano, nitro, amino, C1-C4
alkylamino optionally substituted by a halogen atom or halogen atoms, arylamino
optionally substituted by a halogen atom or halogen atoms, aralkylamino optionally
substituted by a halogen atom or halogen atoms, C1-C4 aliylsulfonamido optionally
substituted by a halogen atom or halogen atoms, C1-C4 alkanoylarnido optionally
substituted by. a halogen atom or halogen atoms, arylsulfonamido, C1-C4
alkylsulfonyloxy, cafboxyl, trifluoromethyl, trifluoromethoxy, C1-C4 alJkyl-S02-NH-
CH2-, NH2-(CH2)1-4-S02-NH-, NH2-(CH2)1-4-(CO)-NH-, sulfamoyl [NH2-S02-],
formyl [-CHO], arnino-methyl [-CH2-NH2], hydroxymethyl, C1-C= alkyl, C1-C4
alkoxymethyl, halogenmethyl, tetrazolyl group, or C1-C4 ; alkoxy, .C1-C4
alkoxycarbonyl, C1-C6 alkanoyloxy, phenyl or C1-C4 alkoxy groups, optionally
substituted by amino group, or
the neighboring X and Y groups in given case together with one or more identical or different
additional hetero atom and -CH= and/or -CH2- groups can form an optionally
substituted 4-7 membered homo- or heterocyclic ring, preferably morpholine, pyrrole,
pyrrolidine, oxo- or thioxo-pyrrolidine, pyrazole, pyrazolidine, imidazole,
imidazolidine, oxo- or thioxo-imidazole or imidazolidine, l,4-oxazine, oxazole,
oxazolidine, oxo- or thioxo-oxazolidine, oxo- or thioxo-thiazolidine or 3-oxo-l,4-
Z is hydrogen or halogen atom, nitro, amino, C1-C4 alkyl, C1-C4 alkoxy, cyano,
trifluoromethyl, trifluoromethoxy group -
and optical antipodes, racemates and salts thereof.
Furthermore objects of the present invention are' the pharmaceutical compositions
containing new 4-benzylidene-piperidin derivatives of formula (I) or optical antipodes or
racemates or the salts thereof as active ingredients.
Further objects of the invention are the processes for producing new 4-benzylidene-
piperidin derivatives of formula (I), and the pharmaceutical manufacture of medicaments
containing these compounds, as well as the process of treatments with these compounds, "which
means administering to a mammal to be treated - including human - effective amount/amounts of-
new benzylidene piperidine derivatives of formula (I) of the present invention, as such' or as
According to the invention the carboxylic acid amide, compounds of formula (I) can be
prepared by the following process.
For producing compound of formula (I), where X, Y and Z are as defined for formula (I),
a secondary amine of formula (II)
- where Z has the same meaning as given for formula (I) - is reacted with ethyl oxalylchloride in
a suitable solvent in the presence of a base,
the obtained ester compound of formula (HE)
- where Z has the same meaning as given for formula (I) - is saponified with an alkali hydroxide
the obtained oxalamid acid of formula (IV)
wherein the meaning of Z is as described above for formula (I) or a reactive derivative of it is
reacted with an aniline of formula (V)
- wherein the meaning of X and Y are as given before for formula (I) -,
then the obtained 4-benzylidene-piperidin derivatives of formula (I) - wherein the
meaning of X, Y, Z are as defined for formula (I) - in given case are transformed into another
compounds of formula (1) by introducing new substituents and/or modifying or removing the
existing ones, and/of by forming salt and/or by liberating the compound from salts, and/or by
resolving the obtained racemates using optically active acids or bases by known methods;
The reaction of the carboxylic acid of formula (II) and the aniline' of formula (V), i.e. the
amide bond formation is preferably carried out by preparing an active derivative from the
carboxylic acid of formula (H) and this is reacted with the aniline of formula (V) preferably in the
presence of a base.
The transformation of a carboxylic acid into an active derivative is carried out in situ
during the amide bond formation in a solvent (for example dimethylformamide, acetdnitrile,
chlorinated hydrocarbons or hydrocarbons). The active derivatives can be acid chlorides (for
example prepared from carboxylic acid with thionyl chloride), mixed anhydrides (for example
prepared from carboxylic acid with isobutyl chloroformate in the presence of a base, e.g.
triemylamine), active esters (for example prepared from carboxylic acid with hydroxybenztriazol
and dicyclohexyl-carbodiimide or 0-benzotriazol-l-yl-N,'N,N\N'-tetramethyluronium
hexafluorophosphate (HBTU) in the presence of a base e.g. triethylamine). The active derivatives
are prepared between room temperature and 0 °C. The necessary reaction time is 6-20 h. The
reaction mixture is purified by column chromatography using Kieselgel 60 (Merck) as adsorbent
and a proper eluent. The proper fractions are concentrated to give the pure product. The quality
and the quantity of the product are determined by HPLC-MS method.
The anilines of formula (V) are either commercially available or can be synthesized by
different known methods. The syntheses of some commercially not available anilines of formula
(V) and the carboxylic acids of formula (IV) are described in the Examples.
As said, the new 4-benzylidene-piperidin derivatives of formula (I) of the present
invention are highly effective and selective antagonists of NMDA receptor, and moreover most
of the compounds are selective antagonist of NR2B subtype of NMDA' receptor. For
characterization of the NR2B selective NMDA antagonist potency of the compounds we used
cultured cortical neurones expressing predominantly NR2B subunit contammg-NMDA receptors.
To prove their selectivity HEK-293 cells transfected with NR1/NR2A subunit combinations were
used. To measure the in vivo analgesic potency and side effect liability of potent NR2B selective
antagonists we used the mouse formalin and locomotor activity tests, respectively..
Expression of recombinant NMDA receptors
To prove NR2B selectivity of the compounds, that is to investigate their effect on NR2A
containing NMDA receptors, we tested the most potent ones on cell lines stably expressing
recombinant NMDA receptors with subunit compositions of NR1/NR2A. cDNAs of human NR1
and NR2A subunits subcloned into inducible mammalian expression vectors were introduced
into HEK 293 cells lacking NMDA receptors using a cationic lipid-mediated transfection method
[Biotechniques, 22, 982-987. (1997); Neurochemistry International, 43. 19-29. (2003)].
Resistance to neomycin and hygromycin was used to screen for clones possessing both vectors
and monoclonal cell lines were established from the clones producing the highest response to
NMDA exposure. Compounds were tested for their inhibitory action on NMDA evoked cytosolic
calcium elevations in fluorescent calcium measurements. Studies were performed 48-72 h after
. addition of the inducing agent. Ketamine (500 µM) was also present during the induction in order
to prevent cytotoxicity.
Assessment of NMDA antagonist potency in vitro by measurement of intracellular calcium
concentration with a plate reader fluorimeter in rat cortical cell culture
The intracellular calcium measurements were carried' out on primary: neocortical cell "
cultures derived from 17 day old Charles River rat embryos (for the details on the preparation of
neocortical cell culture see Johnson, M.I.;Bunge, R.P. (1992):. Primary cell cultures of peripheral
and central neurons and glia. In: Protocols for Neural Cell Culture, eds: Bedoroff, S.; Richardson
A., The Humana Press Inc., 51-75.) After isolation the cells were plated onto standard 96-well
microplates and the cultures were maintained in an atmosphere of 95% air-5% CO2 at 37 °C until
the calcium measurements.
The cultures were used for the intracellular calcium measurements after 3-7 days in vitro.
The.cells at this in vitro age are believed to express predominantly NR2B containing NMDA
receptors [Mol. Pharmacol. 45 846-853. (1994)]. Before the measurement the cells were loaded
with a fluorescent Ca2+-sensitive dye, Fluo-4/AM (2uM). To stop loading the cells were washed
twice with the solution used for the measurement (140 mM NaCl, 5 mM KCl 2 mM CaCl2, -5
mM HEPES, 5 mM HEPES-Na, 20 mM glucose, 10 µM glycine, pH=7.4). After washing, the-
test compounds.were added to the cells in the above solution (90 µ]/well). Intracellular calcium
measurements were carried out with a plate reader fluorimeter: elevation of Fluo-4-fmorescence
and so, intracellular calcium concentration was induced by application of 40 µM NMDA.
Inhibitory potency of the test compounds was assessed by measuring the reduction in the calcium
elevation in the presence of different concentrations of the compounds.
Dose-response curves and IC5o-values were calculated using data derived from at least
three independent experiments. Inhibitory potency of a compound at a single concentration point
was expressed as percent inhibition of the NMDA response. Sigmoidal concentration-inhibition
curves were fit to the data and IC50 values were determined as the concentration that produces
half of the maximal inhibition caused by the compound.
In Table 1, NR2B antagonist potencies of the most effective compounds of this invention
determined in this test are listed. The results with several known selective.NR2B antagonist
reference compounds and the non-selective NMDA receptor antagonist MK-801 are given in
The reference compounds are as follows:
Co 101244: l-[2-(4-hydroxyphenoxy)ethyl]-4-hydroxy-4-(4-rnethylbenzyl)piperidine
EMD 95885: 6:[3-(4-fluorobenzyl)piperidine-l-yl]propionyl]-2,3-dihydro-benzoxazol-2-on
Ro 256981: R-(R*,S*)-l propanol.
Mouse formalin test for measurement of in vivo efficacy
Injection of diluted formalin into the hind paw of rats or mice is known to elicit a biphasic
' pain-related behaviour measured as time spent by licking/biting of the injured paw. The second
phase is generally defined as pain related events detected in the 15-60 min. time interval after-
formalin injection, with peak activity at around 30 min. It is known that NMDA receptors are
involved in the second phase of response to formalin injection and this behavioural response is
sensitive to blockade of NMD A receptors [Dickenson, A. and Besson J.-M. (Editors): Chapter 1,
pp. 6-7: Animal models of Analgesia; and Chapter 8, pp. 180-183: Mechanism of Central-
Hypersensitivity: Excitatory Amino Acid Mechanisms and Their Control - In Pharmacology of
Pain. Springer-Verlag (Berlin) 1997.] Therefore, we used the second phase of formalin test to
characterize the efficacy of compounds in vivo. Inhibition of the second phase of response is
considered to indicate an analgesic effect against chemically-induced persistent pain [Hunker, S.,
et al.: Formalin Test in. Mice, a Useful Technique for Evaluating Mild Analgesics, Journal of
Neuroscience Methods, 14 (1985) 69-76.]
Male NMRI mice (20-25 g) were used. Prior to the experiment any solid food was
withdrawn for approx. 16 hours but the animals had free access to 20 % glucose solution. The
animals were allowed 1 hour acclimatization period in a glass cylinder (cc. 15 cm in diameter),
then moved to an identical cylinder with a mirror placed behind to facilitate observation. The test
substances were suspended in 5 % tween-80 (10 ml per kg body weight), and administered orally
by gavage 15 rnin before the formalin injection (20 µl of 1 % formalin in 0.9 % saline injected
subcutaneously into the dorsal surface of the right hindpaw). The time spent by licking and biting
of the injected paw was measured from 20 to 25 min. after the formalin injection. For the
determination of ED50 value, various doses (at least five) of the test-substances were given to
groups of 5 mice and the results expressed as % inhibition of'the time spent by licking relative to
a vehicle control group observed on the same day. ED50 values (i.e. the.dose yielding 50 %
inhibition) were calculated by Boltzman's sigmoidal curve fitting.
Measurement of spontaneous locomotor activity in mice
' Male NMRI mice weighing 20-22 g were used in the experiments.
Spontaneous locomotor activity was measured in a four-channel activity monitor. The
apparatus consisted of acrylic cages (43cm x 43cm x 32cm) equipped with 2 x 16 pairs of
photocells along all the bottom axis of the cage. An additional array of photocells (16 pairs) was.
placed along two opposite sides of the cage at the height of 10 cm in order to detect rearing
Experimental groups consisted of 10 animals. Thirty minutes after the oral administration
of the test compound or vehicle (tween-80), the animals were individually placed in one of four
cages for one hour. Horizontal and vertical movements were determined as the number of beam
interruptions for one hour at 15 min intervals.
Mean ± SE of horizontal activity data of each group was calculated then percentual
changes compared to the control (vehicle-treated) group were determined. A compound was
considered to cause locomotor stimulation when its effect exceeded 50 % increase in beam
interruptions. Consequently, doses defined as free from stimulatory action (LMAfree) produced
less than 50 % increase.
Table 3 shows the results obtained with some selected compounds of the present
invention (upper table) and their close benzyl-piperidine analogues (lower table) in the analgesic
and locomotor activity tests. [A = 2-(4-benzyl-piperidin-l-yl)-2-oxo-N-(2-oxo-2>3-dihydro-
benzoxazol-6-yl)-acetamide and B = 2-[4-[4-methyl-benzyl)-piperidin-l-yl]-2-oxo-N-(2-oxo-2,3-
dihydro-lH-indol-5-yl)-acetamide] Thus, pairs 1 - A and 24 - B differ only-in the presence of
double instead of single bound.
Analgesic and motor activity data for the non-selective NMDA receptor antagonist MK-
801 and the selective NR2B antagonists CI-1041 (Soc Neurosci Abst 2000, 26(Part 2):Abst
527.4.), CP-101,606 andRo-256981 are given in Table 4.
* CP-101,606 and Ro-256981 resulted in only 38% and 12% inhibition of formalin response,
respectively, at 20 mg/kg.
It can be seen that the non-selective antagonist of the NMDA receptor, MK-801 increases
locomotor activity in the pharmacologically active dose range. This LMA stimulatory effect is an
untoward side effect. Certain selective NR2B antagonist compounds like the reference molecule
CI-1041 or benzyl-piperidine compounds [A = 2-(4-benzyl-piperidin-l-yl)-2-oxo-N-(2-oxo-2,3-
dihydro-benzoxazol-6-yl)-acetamide and B = 2-[4-[4-methyl-benzyl)-piperidin-l-yl]-2-oxo-N-(2-
oxo-2,3-dihydro-1H-iadol-5-yl)-acetamide] described in patent application WO 2003010159 also
show little separation between the doses causing analgesia and those stimulating locomotor
activity. Surprisingly, the benzylidene-piperidine variants of the latter molecules, that is,
compounds of the present invention do not cause hyperactivity up to very high doses (Table 3).
While TIs of the tested benzylpiperidines with high in vivo potency range from 1 to 8, TIs of their
benzylidenpiperidine counterparts are in a considerably higher range, between 46 and 64 or
higher. This strikingly different profile was not expected after the seemingly minor structural
NR2B antagonists with large TI may be particularly advantageous for pharmacotherapy of
diseases that might be treated with NR2B antagonists. Among benzylidenpiperidines there are
compounds with high efficacy in persistent pain model and with high therapeutic index.
Compounds of the present invention possess much more favourable profile regarding possible
therapeutic use than previously patented compounds.
Disorders which may be beneficially treated with NMDA antagonists acting at NR2B site,
as reviewed recently by Loftis [Pharmacology & Therapeutics, 97 55-85(2003)] include
schizophrenia, Parkinson's disease, Huntington's disease, excitotoxicity evoked by hypoxia and
ischemia, seizure disorders, drug abuse, and pain, especially neuropathic, inflammatory and
visceral pain of any origin [Eur. J. Pharmacol., 429:71-78(2001)].
Due to their reduced side effect liability compared to non-selective NMDA antagonists,
NR2B selective antagonists may have utility in diseases where NMDA antagonists may be
effective, such as amyotrophic lateral sclerosis [Neurol. Res., 21 309-12 (1999)], withdrawal
syndromes of e.g. alcohol, opioids or cocaine [Drug and Alcohol Depend., 59 1-15.(2000)],
muscular spasms [Neurosci. Lett., 73 143-148 (1987)], dementia of various origins [Expert
Opin. Investig. Drugs, 9 1397-406 (2000)], anxiety, depression, migraine, hypoglycemia,
degenerative disorders of the retina (e.g. CMV retinitis), glaucoma, asthma, tinnitus, hearing loss
¦ [Drug News Perspect 11 523-569 (1998) and WO 00/00197 international-patent application].
Accordingly, effective amounts of the compounds of the invention may be beneficially
used for the treatment of traumatic injury of brain or spinal cord, tolerance and/Or dependence to
opioid treatment of pain, withdrawal syndromes of drugs of abuse e.g. alcohol, opioids or
cocaine, ischemic CNS disorders, chronic neurodegenerative disorders, such as e.g. Alzheimer's
disease, Parkinson's disease, Huntington's disease, pain and chronic pain states, such as e.g.
The compounds of the invention as well as their pharmaceutically acceptable salts can be
used as such or suitably in the form of pharmaceutical compositions. These compositions (drugs)
can be in solid, liquid or semiliquid form and pharmaceutical adjuvant and auxiliary materials
can be added, which are commonly used in practice, such as carriers, excipients, diluents,
stabilizers, wetting or emulsifying agents, pH- and osmotic pressure-influencing, flavoring or
aromatizing, as-well as formulation-promoting or formulation-providing additives.
The dosage required to exert the therapeutical effect can vary within broad limits and will
be fitted to the individual requirements in each of the particular cases, depending on the stage of
the disease, the condition and the bodyweight of the patient to be treated, as well as the
sensitivity of the patient against the active ingredient, route of administration and number of
daily treatments. The actual dose of the active ingredient to be used can safely be determined by
the attending physician skilled in the art in the knowledge of the patient to be treated.
The pharmaceutical compositions containing the active ingredient according to the
present invention usually contain 0.01 to 100 mg of active ingredient in a single dosage unit It is;
of course possible that the amount of the active ingredient in some compositions exceeds, the
upper or lower limits defined above.
The solid forms of the pharmaceutical compositions can be for example tablets, dragees,
capsules, pills or lyophilized powder ampoules useful for the preparation of injections. Liquid
compositions are the injectable and infusable compositions, fluid medicines, packing fluids and
drops. Semiliquid compositions can be ointments, balsams, creams, shaking mixtures and
For the sake of a simple administration it is suitable if the pharmaceutical compositions
comprise dosage units containing-the amount of the active ingredient to be administered once, or
a few multiples or a half, third or fourth part thereof. Such dosage units are e;.g. tablets,, which
can be powdered with grooves promoting the halving or quartering -pf the tablet in order to
exactly administer the required amount of the active ingredient
Tablets can be coated with an acid-soluble layer in order to assure the release of the active
ingredient content after leaving the stomach. Such tablets are enteric-coated. A similar effect can
be achieved also by encapsulating the active ingredient.
The pharmaceutical compositions for oral administration can contain e.g. lactose or starch
as excipients, sodium carboxymethylcellulose, methylcellulose, polyvinyl pyrrolidine or starch
paste as binders or granulating agents. Potato starch or microcrystalline cellulose is added as
disintegration agents, but ultraamylopectin or formaldehyde casein can also be used. Talcum,
colloidal silicic acid, stearin,.calcium or magnesium stearate can be used as: antiadhesive and
The tablet can be manufactured for example by wet granulation, followed by pressing-.
The mixed active ingredients and excipients, as well as in given case part of the disintegrants are
granulated with an aqueous, alcoholic or aqueous alcoholic solution of the binders in an
appropriate equipment, then the granulate is dried. The other disintegrants, lubricants and
antiadhesive agents are added to the dried granulate, and the mixture is pressed to a tablet. In
given case the tablets are made with halving groove to ease the administration.
The tablets can be made directly from the mixture of the active ingredient and the proper
auxiliaries by pressing. In given case, the tablets can be coated by using additives commonly
used in the pharmaceutical practice, for example stabilizers, flavoring, coloring agents, suchas
. sugar, cellulose derivatives (methyl- or ethylcellulose, sodium carboxymethylcellulose, etc),
polyvinyl pyrroli'done, calcium phosphate, calcium carbonate, food coloring agents, food laces,
aroma agents, iron oxide pigments, etc. In the case, of capsules the mixture of the active
ingredient and the auxiliaries is filled into capsules.
Liquid oral compositions, for example suspensions, syrups, elixirs can be made by using
water, glycols, oils, alcohols, coloring and flavoring agents.
For rectal administration the composition is formulated in suppositories or clysters. The
suppository can contain beside the active ingredient a carrier, so called adeps pro suppository.
Carriers can be vegetable oils, such as hydrogenated vegetable oils, triglycerides of C12-C18 fatty
acids (preferably the carriers under the trade name Witepsol). The active ingredient is
homogeneously mixed with the melted adeps pro suppository and the suppositories are moulded. -
For parenteral administration the composition is formulated as injection solution. For
manufacturing the injection solution the active ingredients are dissolved in distilled water and/or
in different organic solvents, such as glycolethers, in given case in the. presence of solubilizers,
for example polioxyethylensorbitane-monolaurate, -monooleate, or monostearate (Tween. 20,
Tween 60, Tween 80). The injection solution can also contain different auxiliaries, such as
conserving agents, for example emylendiamine tetraacetate, as well as pH adjusting agents and
buffers and in given case local anaesthetic, e.g. lidocain. The injection solution containing the
active ingredient of the invention is filtered before it is filled into ampoules, and it is sterilized
"If the active ingredient is hygroscopic, then it can be stabilized by liophylization.
Compounds of the present invention were characterized by high performance liquid
chromatography coupled to mass selective detector (LC/MS) using HP 1100 Binary Gradient
chromatography system with Microplate Sampler (Agilent, Waldbronn), controlled by
ChemStation software. HP diode array detector was used to acquire UV spectra at 225 and 240
ran. All experiments were performed using HP MSD (Agilent, Waldbronn) single quadruple
spectrometer equipped with an electrospray ionization source to determine the structure.
The synthesized products were dissolved in 1 ml of DMSO (Aldrich, Germany). 100 ul of
each solution was diluted with DMSO to 1000 ul volume. Analytical chromatographic
experiments were performed on Discovery RP C-16 Amide, 5 cm X. 4.6 mm X 5 urn column
from Supelco (Bellefonte, Pennsylvania) with a flow rate of 1 ml/minute for Qualification. The
obtained compounds were characterized by their k' value (purity, capacity factor). K' factors are
evaluated by the following formula:
k' = (tR-to)/t0
where k'= capacity factor, tR = retention time and to = eluent retention time.
The A eluent was trifluoroacetic acid (TFA) (Sigma, Germany) containing 0.1% water,
the B eluent was 95% acetonitrile (Merck, Germany) containing 0.1% TFA and 5% A eluent.
Gradient eiution was used, starting with 100% A eluent and processing to 100% B eluent over a
period of 5 minutes.
The following examples illustrate the invention without the intention of limitation
Under argon, to a stirred solution of 133.2 g (704 mmol) of N-benzyl-4-piperidone
(Aldrich) and 161g (705 mmol) of benzyl-phosphonic acid diethyl ester (Aldrich) in 1350 ml of
dimethylformamide 40.5g (60 % , 37.5 mmol) of sodium hydride is added at 0 °C. The reaction
mixture is stirred for 2 b at 20 °C, 100 ml of ethanol is added drop wise, poured into 1500 ml of
water and extracted with diethyl ether. The organic layer is dried over sodium sulfate and
concentrated. The crude product is used in the next step. Mp.: oil.
lb) 4-benzylidene-piperidine hydrochloride
To a stirred solution of the previously obtained crude l-benzyl-4-benzylidene-piperidine
(-704 mmol) in 21 of dichloroethane 80 ml (741 rnmoi) of 1-chloroethyl-chloroformate is added
drop wise at 0 °C. The reaction mixture is stirred at 0 °C for lh. and refluxed for' 1 h, then
concentrated and the residue is dissolved in 1 1 of methanol, refluxed for Ih. The reaction
mixture is concentrated and the residue is crystallized with acetone to yield 103.25 g (70.1 %) of
the title compound. Mp.: 186 °C (acetone).
lc) (4-benzvlidene-piperidine-l-yl)-oxo-acetic acid ethyl ester
To a stirred solution of 103.25 g (0.492 mol) of 4-benzylidene-piperidihe hydrochloride
and 144.55 ml (1.039 mol) of triemylamine in 11 of chloroform 55.75 ml (0.499 mol) of ethyl
oxalyl chloride is added drop wise below 10 °C, and the reaction mixture is stirred at room
temperature for 1 h. Then 200 ml of water and 200 ml of 8 % sodium hydrogen carbonate
solution is added to the mixture, the organic layer is separated, dried over sodium sulfate and
concentrated. The crude product is used in the next step. Mp.: oil.
Id) (4-benzylidene-piperidine-l-yl)-oxo-acetic acid
To a stirred solution of the previously obtained crude (4-benzylidene-piperidine-l-yl)-
oxo-acetic acid ethyl ester (-0.492 mol) in 200 ml of ethanol a solution of 27.6 g (0.69 mol) of
sodium hydroxide in 300 ml of water and 500 ml of ethanol is added. The reaction mixture is
stirred at room temperature, for 1 h then cooled and acidified with hydrochloric acid. The
precipitated solid is collected, washed with water to yield 107.32 g (88.9: %) of the title
compound. Mp:: 125 °C (ethanol-water)
A mixture, of 49 mg (0.2 mmol) of (4-benzylidene-piperidine~l-yl)-oxo-acetic acid, 33 µl
(0.24 mmol) of triethylamine, 30 mg(0.2 mmol) of 6-amino-3H -benzoxazol-2-one [J. Chem.
Soc, 321. (1938)] 79.6 mg (0.21 .mmol) of HBTU [0-berizotriazol-l-yl-N,N,N',N'-
tetramethyluronium hexafluorophosphate (Advanced Chem. Tech.)] and 1 ml of
dimethylformamide is stirred at room temperature for 24 h. The reaction mixture is purified by
column chromatography using Kieselgel 60 (Merck) as adsorbent and toluene : methanol = 4:1
as eluent. The quality and the quantity of the product are determined by HPLC-MS method as
described above . k' = 9.66.
Using the above described procedure we prepared the following compounds of formula
0.01-50 % of active ingredient of formula (I), 15-50 % of lactose, 15-50 % of potato
starch, 5-15 % of polyvinyl pyrrolidone, 1-5 % of talc, 0.01-3 % of magnesium stearate, 1-3 % of
colloid silicon dioxide and 2-7 % of ultraamylopectin are mixed, then are granulated by wet
granulation and pressed to tablets.
b) Dragees, filmcoated tablets:
The tablets made according to the method described above are coated by a layer
consisting of entero- or gastrosolvent film, or of sugar and talc. The dragees- are polished by a
mixture of beeswax and carnuba wax.
0.01-50 % of active ingredient of formula (1), 1-5 % of sodium lauryl sulfate, 15-50 % of
starch, 15-50 % of lactose, 1-3 % of colloid silicon dioxide and 0.01-3% of magnesium stearate
are thoroughly mixed, the mixture is passed through a sieve and filled in hard gelatin capsules.
Ingredients: 0.01-15 % of active ingredient of formula (I), 0.1-2 % of sodium hydroxide,
0.1-3 % of citric acid, 0.05-0.2 % of nipagin (sodium methyl 4-hydroxybenzoate), 0.005-0.02 %
of nipasol, 0.01-0.5 % of carbopol (polyacrilic acid), 0.1-5 % of 96 % ethanol; 0.1-1 % of
flavoring agent, 20-70 % of sorbitol (70 % aqueous solution) and 30-50 % of distilled water:
To solution of nipagin and citric acid in 20 ml of distilled water, carbopol is added in
small portions under vigorous stirring, and the solution is left to stand for 10-12 h. Then the
sodium hydroxide in 1 ml of distilled water, the aqueous solution of sorbitol and finally the
ethanolic raspberry flavor are added with stirring. To this carrier the active ingredient is added in
small portions and suspended with an immersing homogenizator. Finally the suspension is filled
up to the desired final volume with distilled water and the suspension syrup is ipassed through a
colloid milling equipment.
For each suppository 0.01-15% of active ingredient of formula (I) and 1-20% of lactose
are thoroughly mixed, then 50-95% of adeps pro suppository (for example Witepsol 4) is melted,
cooled to 35 °C and the mixture of active ingredient and lactose is mixed in it with
hornogenizator. The obtained rnixture is mould in cooled forms.
f) Lyophilized powder ampoule compositions:
A 5 % solution of mannitol or lactose is made with, bidistilled water for injection use, and
the solution is filtered so as to have sterile solution. A 0.01-5 % solution of the active ingredient
of formula (I) is also made with bidistilled water for injection use, and this solution is filtered so-
as to have sterile solution. These two solutions are mixed under aseptic conditions, filled in 1 ml
portions into ampoules, the content of the ampoules is lyophilized, and the ampoules are sealed •
under nitrogen. The contents of the ampoules are dissolved in sterile water or 0.9 %
(physiological) sterile aqueous sodium chloride solution before admi+nistration.
We Claim :
1. New 4-benzylidene-piperidin derivatives of formula (I)
wherein the neighboring X and Y groups together form an optionally substituted ring
selected from pyrrolidine, oxo- or thioxo-pyrrolidine; imidazolidine, oxo- or thioxo-
imidazolidine, oxazolidine, oxo- or thioxo-oxazolidine and oxo- or thioxo-thiazolidine; Z is
hydrogen or halogen atom, nitro, amino, C.sub.l-C.sub.4 alkyl, C.sub.l-C.sub.4 alkoxy,
cyano,trifluoromethyl, trifluoromethoxy group—and optical antipodes, racemates and salts
2. A compound of the following group of 4-benzylidene-piperidin derivatives belonging to
the scope of claim 1:
2-(4-benzylidene-piperidin-1 -yl)-2-oxo-N-(2-oxo-2,3-dihydro-benzooxazol-6- -yl)-acetamide;
2-[4-(4-methoxy-benzylidene)-piperidin-1 -yl]-2-oxo-N-(2-oxo-2,3-dihydro-benzoimidazol -5-
-acetamide and optical antipodes, racemates and salts thereof.
3. A pharmaceutical composition comprising an effective amount of the a compound of
formula (I) - in claim 1 and pharmaceutically acceptable carriers, excipients, diluents, stabilizers,
wetting or emulsifying agents, pH- and osmotic pressure-influencing, flavoring or aromatizing,
formulation-promoting or formulation-providing additives.
4. Process for preparing the 4-benzylidene-piperidin derivatives of formula (I) in claim 1
comprising reacting a secondary amine of formula (II)
where Z has the same meaning as given for formula (I) - with ethyl oxalylchloride in a
suitable solvent in the presence of a base,
saponifying the obtained ester compound of formula (III)
where Z has the same meaning as given for formula (I) - with an alkali hydroxide and
reacting the obtained oxalamid acid of formula (IV)
wherein the meaning of Z is as described above for formula (I) - or a reactive derivative
of it with an aniline of formula (V)
wherein the meaning of X and Y are as given before for formula (I) - in dichloromethane,
then transforming optionally the so obtained 4-benzylidene-piperidin derivatives of formula (I) -
- in claim 1 - into other compounds of formula (I) by introducing new substituents and/or
modifying or removing the existing ones, and/or by forming salt and/or liberating the compound
of formula (I) from salts by known methods.
5. Process as claimed in claim 4, comprising by reacting an active derivative of the
carboxylic acid of formula (IV) - wherein the meaning of Z is as given in claim 1 - with the
aniline of formula (V) - wherein the meaning of X and Y are as given in claim 1 - in the presence
of a base.
6. Process as claimed in claim 4, comprising reacting the carboxylic acid of formula (IV) -
wherein the meaning of Z is as given in claim 1 - with the aniline of formula (V) - wherein the
meaning of X and Y are as given in claim 1 - in the presence of triethylamine and O-benzotriazol
-l-yl-N,N,N',N'-tetramethyluronium hexafluorophosphate (HBTU) in dimethylformamide.
7. Process for manufacturing pharmaceutical compositions having NR2B selective NMDA
receptor antagonist effect, comprising mixing a 4-benzylidene-piperidin derivative of formula (I)
in claim 1 - or optical antipodes or racemates or the pharmaceutically acceptable salts thereof as
active ingredients and auxiliary materials, carriers, excipients, diluents, stabilizers, wetting or
emulsifying agents, pH- and osmotic pressure-influencing, flavoring or aromatizing, as well as
formulation-promoting or formulation-providing additives.
The present invention relates to new 4-benzylidene-piperidin derivatives of formula (I), useful as NMDA, in a par-
ticular NR2B subunit containing receptor antagonists and analgesica.
|Indian Patent Application Number||232/KOLNP/2007|
|PG Journal Number||16/2012|
|Date of Filing||18-Jan-2007|
|Name of Patentee||RICHTER GEDEON VEGYÉSZETI GYÁR RT.|
|Applicant Address||H-1103, BUDAPEST, GYÖMRŐI ÚT 19-21|
|PCT International Classification Number||C07D401/00; C07D413/00; C07D417/00|
|PCT International Application Number||PCT/HU2005/000077|
|PCT International Filing date||2005-07-21|