Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Reexamination Certificate
2002-05-03
2004-06-01
Bernhardt, Emily (Department: 1624)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
C544S373000, C544S392000
Reexamination Certificate
active
06743796
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the field of dopamine receptor partial agonists, and in particular to novel 4-piperazinyl-isatins, their preparation, and their therapeutic use, e.g., in the treatment of psychosis.
Dopamine antagonists have been used for years in the treatment of disorders of the dopaminergic system, such as schizophrenia. These antagonists block the D
2
receptors. Unfortunately, this causes undesirable side effects. Dopamine autoreceptor agonists, including partial agonists, can be used to induce antipsychotic activity without causing the same side effects as antagonists.
Intrinsic activity at the dopamine D
2
receptor may be predicted using the ratio of the “low-affinity agonist” (LowAg) state of the receptor and the “high-affinity agonist” (HighAg) state of the receptor, i.e. LowAg/HighAg. These ratios correlate with the agonist, partial agonist, and antagonist activities of a given compound, and these activities characterize a compound's ability to elicit an antipsychotic effect.
WO 94 13659 discloses fused benzo compounds of the general Formula I
wherein X is selected from a broad base of divalent 3-4 membered groups, including the possibility of forming imidazoles, which potently bind to the 5-HT
1A
receptor and have central serotonergic 5HT
1A
activity for the treatment of certain psychic and neurological disorders.
EP 0138280 discloses piperazinyl compounds of Formula II having a bicyclic heteroaryl radical in the 4-position and a heteroaryl-, aryl-, or alkyl substituted carbamoylethyl or carbamoylpropyl in the 1-position. These compounds are alleged to show blood pressure lowering effect through a central mechanism. When n=1, the compounds are piperazines.
WO 94 15919 (Formula III) and WO 94 21610 (Formula IV) disclose piperazine derivatives which act on the central nervous system by binding to 5-HT receptors, particularly 5-HT
1A
type, for the use in the treatment of CNS disorders, such as anxiety, depression, and cognition disorders. In both Formula III and Formula IV, Z and R
1
refer to heteroaryl groups.
R. E. Mewshaw et al (
Bloorg. & Med. Chem. Leff
. 8, 2675-2680, 1998) describe heteroarylpiperazines of Formula V which have excellent affinity for the D
2
receptor, and are potentially useful as antipsychotic agents.
E. Giovannini et al. (
Helv. Chim. Acta
40, 249, 1957) reported that 4-amino-isatin had been prepared.
Several techniques useful for forming derivatives are known in the art. G. Friedmann et al. (
J. Org. Chem
. 44, 237, 1979) described lithiation of N,N,N′,N′-tertramethyl-ortho- and para-phenylenediamine. An improvement was revealed by W. Fuhrer and H. W. Gschwend (
J. Org. Chem
. 44, 1133, 1979) which involved a combined ortho-directing effect as illustrated by lithiation of N-pivaloyl-3-methoxyaniline. P. Hewawasam and N. A. Meanwell (
Tetrahedron Letters
, 3, 7303, 1994) disclosed the conversion of several 3-(suitably substituted) anilines into corresponding 2-(&agr;-ketoesters) by means of diethyl oxalate; subsequent hydrolytic deprotection produced substituted isatins. However, the literature does not disclose the analogous lithiation of metaphenylenediamine derivatives, such as 3-(4′-R-piperazin-1′-yl)anilines. The choice of the directing and protecting groups appears to be of critical importance in lithiating different species, and such choice is by no means obvious, as is indicated by the disclosures of P. Hewawasam and N. A. Meanwell (
Tetrahedron Letters
, 35, 7303, 1994) and V. Snieckus,
Lect. Heterocylic Chem
., 95-106, 1984).
SUMMARY OF THE INVENTION
The present invention comprises novel 4-piperazinyl compounds of Formula VI
wherein
Y is hydrogen, methyl, methoxy, methylthio, or trifluoromethyl;
R is H, C
1-3
alkyl, or (CH
2
)
n
Ar;
n is 0, 1, or 2; and
Ar is phenyl or methoxyphenyl,
and pharmaceutically acceptable salts thereof.
The present invention further comprises compounds of Formula VII and Formula VIII
which are useful in making compounds of Formula VI, wherein Y and R have the same definition as in Formula VI. Ph represents a phenyl group and Et represents an ethyl group.
The present invention also includes compositions containing Formula VI compounds; methods for making compounds of Formula VI and Formula VII; and methods of treatment comprising administering a compound of Formula VI or a pharmaceutically acceptable salt thereof to a mammal to reduce dopamine synthesis, and/or to treat disorders of the dopaminergic system, such as schizophrenia, Parkinson's disease, hyperprolactinemia, depression, and Tourette's syndrome. Preferably, the compounds of the invention are those wherein R′ is a hydrogen atom and R is not a hydrogen atom; such compounds wherein Ar is phenyl, n is 1, and Y is hydrogen are more preferred.
DESCRIPTION OF INVENTION
This invention comprises novel isatins substituted in position 4 with a tertiary amino group, preferably 4-(4′-R-piperazin-1′-yl)isatins, where R is H, alkyl, or aralkyl. One highly preferred embodiment of the invention is 4-(4′-benzylpiperazin-1′-yl)isatin.
The 4-piperazinylisatins of this invention have biological activity as an antipsychotic agent. These compounds are essentially free from extrapyramidal side effects (EPS). The compounds of this invention are selective autoreceptor agonists, functioning primarily to activate only autoreceptors versus postsynaptic D
2
dopamine receptors. As such, they provide functional modulation of dopamine systems of the brain without the excessive blockade of the postsynaptic dopamine receptors, which have been observed to be responsible for the serious side effects frequently exhibited by agents found otherwise clinically effective for treatment of schizophrenia. Activation of the dopamine autoreceptors results in reduced neuronal firing as well as inhibition of dopamine synthesis and release and therefore provide a means of controlling hyperactivity of the dopaminergic systems.
More specifically, the compounds of this invention comprise those depicted by the following Formula VI:
wherein
Y is hydrogen, methyl, methoxy, methylthio, or trifluoromethyl;
R is H, C
1-3
alkyl, or (CH
2
)
n
Ar;
n is 0, 1, or 2; and
Ar is phenyl or methoxyphenyl,
and pharmaceutically acceptable salts thereof.
Those skilled in the art will be readily able to determine which salts of the compounds of this invention are pharmaceutically acceptable. The pharmaceutically acceptable salts of the compounds of this invention include those derived from such organic and inorganic acids, such as: acetic, lactic, citric, fumaric, tartaric, succinic, maleic, malonic, oxalic, hydrochloric, hydrobromic, phosphoric, nitric, sulfuric, methanesulfonic, methylbenzene sulfonic, and similarly known acceptable acids.
The term alkyl as used herein includes both straight chain and branched moieties.
A preferred embodiment of this invention is compounds of formula VI wherein Y is hydrogen, methyl, methoxy at the 5 or 7 position, methylthio at the 7 position, or trifluoromethyl at the 5 or 6 position, and R is (CH
2
)Ar. Highly preferred compounds of this invention include those compounds of Formula VI in which Y=H, n=1 and Ar=phenyl.
The compounds of this invention can be prepared from starting materials that are either commercially available or can be prepared by standard procedures known to those skilled in the art. The compounds of Formula VI can be generally prepared as shown in Reaction Scheme I, which specifically illustrates the reaction scheme for making 4-(4-benzyl-piperazin-1-yl)-1H-indole-2.3-dione.
Compound 7 may be useful in the preparation of more substituted isatins, for example by substitution on the isatin nitrogen, or removal of the piperazinyl benzyl group and subsequent substitution with alkyl or aralkyl groups.
Other compounds of this invention wherein Y is not H may be prepared in a manner analogous to Reaction Scheme I. Illustrative examples of these compounds are presented in the table below, which shows the derivatives of co
Greenblatt Lynne P.
Jirkovsky Ivo
Mewshaw Richard E.
Bernhardt Emily
Hild Kimberly R.
Mazzarese Joseph
Wyeth
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