Derivatives of azetidine and pyrrolidine

Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...

Reexamination Certificate

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C548S559000, C548S556000

Reexamination Certificate

active

06281243

ABSTRACT:

This application is a 371 of PCT/EP98/01282 Feb. 26, 1998.
The invention relates to derivatives of azetidine and pyrrolidine, to pharmaceutical compositions comprising the same, a process for their preparation, as well as the use of derivatives of azetidine and pyrrolidine for the preparation of a medicament which acts on the central nervous system.
In recent years the contribution of serotonergic activity to the mode of action of antidepressant drugs has been well documented and compounds which enhance activity in the serotonin system have been developed and successfully introduced as antidepressants. Serotonin reuptake inhibitors (SRI) work by increasing the amount of serotonin available at the synapse. Although the SRI's have more favourable side effect profiles than previous generations, they are not devoid of side effects and still suffer from a slow onset of action [Andrews and Nemeroff, “Contemporary management of depression”—American Journal of Medicine 97(6A): 24S-32S (1994); Leonard, “The comparative pharmacology of new antidepressants”—Journal of Clinical Psychiatry 54(Suppl): 3-15 (1993)]. Moreover, the mechanism of action of the SRI's although specific for serotonin, is not selective in that they effect activity at a multitude of different serotonin receptor subtypes. This broad spectrum of activity may lead to many of the side effects associated with the SRI's e.g. nausea from activation of 5-HT3, headache due to activation of 5-HT2B. Thus, SRI's can alter the function of several 5-HT2 receptor subtypes, however, the efficacy of these drugs may correlate most strongly with their effects on the 5-HT2C system [(Broekkamp and Berendsen “The importance of 5-HT1C receptors for anti-depressant effects”—Polish Journal of Pharmacology and Pharmacy 44(Suppl): 20 (1992); Cesana et al “Mesulergine antagonism towards the fluoxetine anti-immobility effect in the forced swimming test in mice”—Journal of Pharmacy and Pharmacology 45: 473-475 (1993); Berendsen and Broekkamp “Comparison of stimulus properties of fluoxetine and 5-HT receptor agonists in a conditioned taste aversion procedure”—European Journal of Pharmacology 253: 83-89 (1994)]. These data suggest that compounds which selectively activate the 5-HT2C receptor will be effective in the treatment of affective disorders and related conditions.
The invention relates to compounds according to the formula I
wherein A is an optionally unsaturated 5- or 6-membered ring, which may comprise a heteroatom selected from N, O and S and which may be substituted with oxo or (1-6C)alkyl; R
1
, R
2
and R
3
are independently H, (1-6C)alkyl, (1-6C)alkoxy, (1-6C)alkoxy-(1-6C)alkyl, carbo(1-6C)alkoxy or halogen; X is O or S; and n is 1 or 2; or a pharmaceutically acceptable salt thereof, with the exception of 3-(naphth-1-yl-oxy)-pyrrolidir and 3-(5,6,7,8-tetrahydro-naphth-1-yl-oxy)-pyrrolidin. The compounds have a selective effect on 5-HT2C receptors in the central nervous sytem.
In U.S. Pat. No. 4,452,809 [filed Apr. 22, 1983] 3-aryloxy-4-hydroxypyrrolidines were disclosed, wherein it was found that 3-naphthyl or 3-indenyloxy-4-hydroxypyrrolidines have antiarrhythmic activity, whereas 3-phenoxy-4-hydroxypyrrolidines were found to have antidepressant activity. Some years earlier, in DT 2,738,477 [priority date Sep. 1, 1977] also 3-aryloxy-4-hydroxypyrrolidines were disclosed, wherein the preferred compounds with antidepressant activity were also 3-phenoxy derivatives. Other 3-aryloxypyrrolidines wherein the pyrrolidine-group of all compounds is N-substituted, having an effect on the serotonin receptor, were disclosed in EP 0,338,331 [priority date Apr. 19, 1988].
Surprisingly, after many years of research, it has now been found, that the compounds of formula I, (bicyclic aryl)oxy-substituted pyrrolidines and (bicyclic aryl)oxy-substituted azetidines wherein the 5- or 4-membered heterocycle is not substituted at any position in the ring, have a selective effect on 5-HT2C receptors in the central nervous sytem. Also the compounds 3-(naphth-1-yl-oxy)-pyrrolidin and 3-(5,6,7,8-tetrahydro-naphth-1-yl-oxy)-pyrrolidin, known as intermediates but not claimed in EP 0,338,331, were found to have this effect. Therefore, also protection is sought for the use of these compounds and for pharmaceutical compositions comprising them. Thus, the invention also pertains to the first medical use of the compounds according to formula 1, i.e. including the compounds 3-(naphth-1-yl-oxy)-pyrrolidin, 3-(5,6,7,8-tetrahydro-naphth-1-yl-oxy)-pyrrolidin for use as a medicament (or, in other words, for use in therapy).
The use of a selective 5-HT2C agonist ensures that pharmacological activity occurs immediately and preferentially at the 5-HT2C receptors allowing a much quicker onset of selective pharmacological activation than can be observed with SRI's. Moreover the selectivity of the compound reduces the potential for adverse effects mediated by other serotonin receptors e.g. nausea, headache, effects which may hinder compliance and thus interfere with efficacy.
The compounds of the present invention act on the central nervous system, in particular as antidepressants, and against obsessive compulsive disorders, anxiety disorders including generalised anxiety, panic attacks, agoraphobia, eating disorders such as obesity, urinary incontinence, impotence, aggression and drug abuse such as alcohol or narcotic addiction.
Preferred compounds according to the invention have the formula I wherein the heteroatom in A, if present, is N or S; R
1
is H, (1-6C)alkyl, (1-6C)alkoxy, (1-6C)alkoxy-(1-6C)alkyl; R
2
is H, (1-6C)alkoxy, carbo(1-6C)alkoxy or halogen and R
3
is H, (1-6C)alkyl, (1-6C)alkoxy or halogen.
More preferred are compounds of the formula (Ia)
wherein A is an unsubstituted saturated 5-membered or optionally aromatic 6-membered ring, which may comprise a nitrogen atom adjacent to the position indicated with an asterisk; R
1
is H or (1-6C)alkoxy; R
2
is H, (1-6C)alkoxy or halogen; R
3
is H or halogen; and n is 1 or 2. More preferred are the compounds of formula (Ia) wherein A is an unsubstituted saturated 5-membered or optionally aromatic 6-membered ring; R
1
is (1-6C)alkoxy and R
2
and R
3
are H. Most preferrably, A in formula (Ia) is a 5-membered ring and R
1
is methoxy, in particular when n is 2.
The term (1-6C)alkyl means a branched or unbranched alkyl group having 1 to 6 carbon atoms, such as methyl, ethyl, t-butyl, isopentyl, and the like. The most preferred alkyl group is methyl.
The term (1-6C)alkoxy means an alkoxy group having 1-6 carbon atoms, the alkyl moiety of which having the meaning as previously defined. The most preferred alkoxy group is methoxy.
The term halogen means fluorine, chlorine or bromine.
The compounds according to formula I may be prepared in a manner conventional for such compounds. To that end, compounds of general formula II, wherein A, R
1
, R
2
, R
3
, X and n are as previously defined and P is any N-protecting group, stable under alkaline conditions [suitable N-protecting groups can be found in T. W. Green and P. G. M. Wuts: Protective Groups in Organic Synthesis, Second Edition (Wiley, NY, 1991)], are deprotected using the appropriate conditions such as catalytic hydrogenation or intermediate carbamate formation, followed by reaction with alcohols. Optionally at the same time, a salt may be formed.
The compounds according to general formula II may be prepared by arylether formation of suitable N-protected 3-hydroxy-azetidines or -pyrrolidines, wherein the protecting group is as hereinbefore defined, with appropriately substituted aromatic or heteroaromatic compounds bearing a suitable leaving group. Alternatively, N-protected-azetidines or -pyrrolidines bearing a suitable leaving group at the 3-position, such as halogen, triflate, tosylate or mesylate, can be reacted with appropriately substituted aromatic or heteroaromatic compounds bearing a hydroxy, or mercapto group.
The compounds of the invention, which can be in the form of a

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