Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-12-11
2003-07-22
Low, Christopher S. F. (Department: 1653)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C514S019300, C530S333000, C530S338000
Reexamination Certificate
active
06596867
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the (L)-(+)-tartaric acid salt of 2-amino-N-{1-(R)-(2,4-difluoro-benzyloxymethyl)-2-oxo-2-[3-oxo-3a-(R)-pyridin-2-ylmethyl-2-(2,2,2-trifluoro-ethyl)-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl]-ethyl}-2-methyl-propionamide which is a growth hormone secretagogue.
Growth hormone (GH), which is secreted from the pituitary gland, stimulates growth of all tissues of the body that are capable of growing. In addition, growth hormone is known to have the following basic effects on the metabolic processes of the body:
1. Increased rate of protein synthesis in substantially all cells of the body;
2. Decreased rate of carbohydrate utilization in cells of the body; and
3. Increased mobilization of free fatty acids and use of fatty acids for energy.
Deficiency in growth hormone results in a variety of medical disorders. In children, it causes dwarfism. In adults, the consequences of acquired GH deficiency include profound reduction in lean body mass and concomitant increase in total body fat, particularly in the truncal region. Decreased skeletal and cardiac muscle mass and muscle strength lead to a significant reduction in exercise capacity. Bone density is also reduced. Administration of exogenous growth hormone has been shown to reverse many of the metabolic changes. Additional benefits of therapy have included reduction in LDL cholesterol and improved psychological well-being.
In cases where increased levels of growth hormone were desired, the problem was generally solved by providing exogenous growth hormone or by administering an agent which stimulated growth hormone production and/or release. In either case the peptidyl nature of the compound necessitated that it be administered by injection. Initially the source of growth hormone was the extraction of the pituitary glands of cadavers. This resulted in an expensive product, and carried with it the risk that a disease associated with the source of the pituitary gland could be transmitted to the recipient of the growth hormone (e.g., Jacob-Creutzfeld disease). Recently, recombinant growth hormone has become available which, while no longer carrying any risk of disease transmission, is still a very expensive product which must be given by injection or by a nasal spray.
Most GH deficiencies are caused by defects in GH release, not primary defects in pituitary synthesis of GH. Therefore, an alternative strategy for normalizing serum GH levels is by stimulating its release from somatotrophs. Increasing GH secretion can be achieved by stimulating or inhibiting various neurotransmitter systems in the brain and hypothalamus. As a result, the development of synthetic growth hormone-releasing agents to stimulate pituitary GH secretion are being pursued, and may have several advantages over expensive and inconvenient GH replacement therapy. By acting along physiologic regulatory pathways, the most desirable agents would stimulate pulsatile GH secretion, and excessive levels of GH that have been associated with the undesirable side effects of exogenous GH administration would be avoided by virtue of intact negative feedback loops.
Physiologic and pharmacologic stimulators of GH secretion include arginine, L-3,4-dihydroxyphenylalanine (L-DOPA), glucagon, vasopressin, and insulin induced hypoglycemia, as well as activities such as sleep and exercise, indirectly cause growth hormone to be released from the pituitary by acting in some fashion on the hypothalamus perhaps either to decrease somatostatin secretion or to increase the secretion of the known secretagogue growth hormone releasing factor (GHRF) or an unknown endogenous growth hormone-releasing hormone or all of these.
This invention also relates to a method of treating insulin resistant conditions such as Non-Insulin Dependent Diabetes (NIDD) and reduced glycemic control associated with obesity and aging in a mammal in need thereof which comprises administering to said mammal an effective amount of the L-(+)-tartrate salt of the compound of Formula I, shown below.
Other compounds have been developed which stimulate the release of endogenous growth hormone such as analogous peptidyl compounds related to GRF or the peptides of U.S. Pat. No. 4,411,890. These peptides, while considerably smaller than growth hormones are still susceptible to various proteases. As with most peptides, their potential for oral bioavailability is low.
WO 94/13696 refers to certain spiropiperidines and homologues which promote release of growth hormone. Preferred compounds are of the general structure shown below.
WO 94/11012 refers to certain dipeptides that promote release of growth hormone. These dipeptides have the general structure
where L is
The compounds of WO 94/11012 and WO 94/13696 are reported to be useful in the treatment of osteoporosis in combination with parathyroid hormone or a bisphosphonate.
A generic disclosure of pharmaceutically-acceptable salts of the compound of Formula I of the instant application is disclosed, and the free base of the compound of Formula I of the instant invention is disclosed and claimed, in co-pending PCT application Ser. No. PCT/IB 96/01353 having an international filing date of Dec. 4, 1996, assigned to the assignee hereof.
It has been found that the L-(+)-tartaric acid salt of the compound of Formula I, shown below, can be isolated in crystalline form which has advantageous properties such as ease of making a formulation, high solubility, good stability and is more easily purified than a non-crystalline form.
SUMMARY OF THE INVENTION
This invention provides the L-(+)-tartaric acid salt of the compound of Formula I
The “indicates a stereochemical center. Preferred of the compound of formula I are the stereochemical mixture or separated isomers having the configurations 3a-(S), 1-(R); 3a-(S), 1-(S); 3a-(R), 1-(S); and/or 3a-(R), 1-(R) isomers.
This invention also provides: a process for the preparation of the (D)-tararic acid or the (L)-tartaric acid salt of the compound of formula (E),
which comprises reacting the compound of formula (D),
with (D)-tartarc acid or (L)-tartaric acid in about 8:1 to about 9:1 mixture of acetone:water at a temperature between about 0° C. to room temperature. Preferred of the foregoing process is where (D)-tartaric acid is reacted with the compound of formula (D) and the compound of formula (E) has the R-configuration;
a process for the preparation of the compound of formula (J),
which comprises reacting the compound of formula (E),
with the compound of formula (X),
where Prt is an amine protecting group and X is OH, —O(C
1
-C
4
)alkyl or halo, in the presence of an organic base and a peptide coupling reagent at a temperature between about −78° C. to about −20° C. Preferred of the immediately foregoing process is where the peptide coupling reagent is 1-propane phosphonic acid cyclic anhydride and the compound of formula X has the R-configuration and the compound of formula E has the R-configuration. Even more preferred is a where Prt is tert-butyloxycarbonyl in the immediately foregoing process; and
a process for the preparation of the (L)-(+)-tartaric acid salt of the compound of formula I,
which comprises reacting the compound of formula (E),
with the compound of formula (X),
where Prt is an amine protecting group and X is OH, —O(C
1
-C
4
)alkyl or halo, in the presence of an organic base and a peptide coupling reagent at a temperature between about −78° C. to about −20° C., to yield the compound of formula (J),
deprotecting the compound of formula (J) under appropriate deprotecting conditions to yield the compound of formula (K),
reacting the compound of formula (K) with (L)-(+)-tartaric acid in a reaction inert solvent to yield the (L)-(+)-tartaric acid salt of the compound of formula I. Preferred of the immediately foregoing process is where Prt is tert-butoxycarbonyl, even more preferred of the immediately foregoing process is where the peptide coupling reagent is 1-propane p
Carpino Philip Albert
Dasilva-Jardine Paul Andrew
Lefker Bruce Allen
Murry Jerry Anthony
Benson Gregg C.
Low Christopher S. F.
Lukton David
Pfizer Inc.
Richardson Peter C.
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