Dolastatin 15 derivatives Number:7,084,110 from the United States Patent and Trademark Office (PTO) owispatent Compounds of the present invention include cell growth inhibitors which are peptides of Formula I, A-B-D-E-F-(G).sub.r-(K).sub.s-L, (I) and acid salts thereof, wherein A, B, D, E, F, G and K are .alpha.-amino acid residues, and s and r are each, independently, 0 or 1. L is a monovalent radical, such as, for example, an amino group, an N-substituted amino group, a .beta.-hydroxylamino group, a hydrazido group, an alkoxy group, a thioalkoxy group, an aminoxy group, or an oximato group. The present invention also includes a method for treating cancer in a mammal, such as a human, comprising administering to the mammal an effective amount of a compound of Formula I in a pharmaceutically acceptable composition.<H derivatives, Dolastatin, Dolastatin, 15, d, 7084110.html, Patent, pto, 7084110

Title: Dolastatin 15 derivatives

Abstract: Compounds of the present invention include cell growth inhibitors which are peptides of Formula I, A-B-D-E-F-(G).sub.r-(K).sub.s-L, (I) and acid salts thereof, wherein A, B, D, E, F, G and K are .alpha.-amino acid residues, and s and r are each, independently, 0 or 1. L is a monovalent radical, such as, for example, an amino group, an N-substituted amino group, a .beta.-hydroxylamino group, a hydrazido group, an alkoxy group, a thioalkoxy group, an aminoxy group, or an oximato group. The present invention also includes a method for treating cancer in a mammal, such as a human, comprising administering to the mammal an effective amount of a compound of Formula I in a pharmaceutically acceptable composition.

Patent Number: 7,084,110 Issued on 08/01/2006 to Janssen, et al.

Inventors: Janssen; Bernd (Marlborough, MA); Barlozzari; Teresa (Wellesley, MA); Haupt; Andreas (Northborough, MA); Zierke; Thomas (Bohl-Iggelheim, DE); Kling; Andreas (Mannheim, DE)
Assignee: Abbott GmbH & Co., KG (Wiesbaden, DE)

Appl. No.: 10/255,118

Filed: September 25, 2002

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
09618694	Jul., 2000	6458765
08896394	Jul., 1997	6143721

Current U.S. Class: 514/2 ; 514/16; 514/17; 530/328; 530/329; 530/330

Current International Class: A61K 38/00 (20060101)

Field of Search: 514/2,16,17 530/328,329,330

References Cited [Referenced By]

U.S. Patent Documents


4816444	March 1989	Pettit et al.
5502032	March 1996	Haupt et al.
5504191	April 1996	Pettit et al.
5530097	June 1996	Pettit et al.
5554725	September 1996	Pettit
5807984	September 1998	Kling et al.
5831002	November 1998	Haupt et al.
6143721	November 2000	Janssen et al.
6458765	October 2002	Janssen et al.

Foreign Patent Documents


0 398 558	Nov., 1990	EP
0 598 129	May., 1994	EP
WO93/23424	Nov., 1993	WO
WO96/18408	Jun., 1996	WO
WO 96/40751	Dec., 1996	WO
WO 96/40752	Dec., 1996	WO
WO97/17364	May., 1997	WO
WO97/22621	Jun., 1997	WO

Other References

Pettit, G.R., et al., "Isolation of Dolastatins 10-15 from the Marine Mollusc Dolabella Auricularia," Tetrahedron, 49 (42) :9151-9170 (1993). cited by other .
Pettit, G.R., et al. "The Dolastatins 20. A Convenient Synthetic Route to Dolastatin 15," Tetrahedron, 50(42):12097-12108 (1994). cited by other .
Pettit, G.R., et al., "Antineoplastic Agents 337. Synthesis of Dolastatin-10 Strtuctural Modifications," Anti-Cancer Drug Design, 10:529-544 (1995). cited by other .
Bai, R., et al., "Stucture-Activity Studies with Chiral Isomers and with Segments of the Antimitotic Marine Peptide Dolastatin 10," Biochemical Pharmacology 40 (8) :1859-1864 (1990). cited by other .
Bai, R., et al., "Dolastain 15, a potent antimitotic depsipeptide derived from Dolabella auricularia. Interaction with tubulin and effects on cellular microtubules," 1-Pharmacology, Abstract 117: 10373g, p. 41 (1992). cited by other .
Miyazaki, K. et al., "Synthesis and Antitumor Activity of Novel Dolastatin-10 Analogs," Chem. Pharm. Bull., 43 (10):1706-1718 (1995). cit- ed by other .
Pettit , G. R., et al., "The Isolation and Structure of a Remarkable Marine Animal Antineoplastic Constituent: Dolastatin 10," J. Am. Chem. Soc. 109:6883-6885 (1987). cited by other .
Pettit, G. R., et al., "Isolation and Structure of the Cytostatic Depsipeptide Dolastatin 13 from the Sea Hare Dolabella auricularia," J. Am. Chem. Soc., 111 (13) : 5015-5017 (1989). cited by other .
Pettit, G. R., et al., "Isolation and Structure of the Cytostatic Linear Depsipeptide Dolastatin 15," J. Org. Chem., 54:6005-006 (1989). cited by other .
Pettit, G. R., et al., "Antineoplastic Agents. 220. Synthesis of Natural (-)-Dolastatin 15," J. Am. Chem. Soc., 113: 6692-6693 (1991). cited by other.

Primary Examiner: Low; Christopher S. F.
Assistant Examiner: Vakili; Zohreh
Attorney, Agent or Firm: Lahive & Cockfield, LLP. DeConti, Jr., Esq.; Giulio A. Trinque; Brian C.

Parent Case Text

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 09/618,694, filed Jul. 18, 2000, now issued as U.S. Patent No. 6,458,765, which is a continuation of U.S. application Ser. No. 08/896,394, filed Jul. 18, 1997, now issued as U.S. Pat. No. 6,143,721. The contents of the aforementioned applications are hereby incorporated herein by reference.

Claims

We claim:

1. A compound of the formula A-B-D-E-F-(G).sub.r-(K).sub.s-L, wherein r and s are each independently, 0 or 1; A is a proline derivative of Formula II.sub.a, ##STR00038## wherein n.sub.a is 0 to 3; R.sub.a is hydrogen, or unsubstituted or fluorine-substituted normal, branched or cyclic C.sub.1 C.sub.3-alkyl; R.sup.1.sub.a is hydrogen, C.sub.1 C.sub.3-alkyl, phenyl, or substituted phenyl; or R.sub.a and R.sup.1.sub.a together form a propylene bridge; and R.sup.2.sub.a, R.sup.3.sub.a, R.sup.4.sub.a and R.sup.5.sub.a are each, independently, hydrogen or alkyl; or an .alpha.-amino acid derivative of Formula III.sub.a, ##STR00039## wherein R.sub.a is hydrogen or unsubstituted or fluorine-substituted C.sub.1 C.sub.3-alkyl; R.sup.1.sub.a a is C.sub.1 C.sub.4-alkyl; R.sup.6.sub.a is alkyl, substituted alkyl, alkenyl, phenyl or substituted phenyl; or R.sup.1.sub.a is an alkyl group and R.sup.6.sub.a is C.sub.1 C.sub.6-alkyl, cycloalkylmethyl, benzyl or substituted benzyl; and R.sup.7.sub.a is hydrogen or alkyl; or an .alpha.-amino acid derivative of Formula IV.sub.a, ##STR00040## wherein m.sub.a is 1 or 2; R.sup.7.sub.a is hydrogen or alkyl; R.sub.a is hydrogen, or unsubstituted or fluorine-substituted alkyl; or an .alpha.-amino acid derivative of Formula V.sub.a, ##STR00041## wherein R.sup.7.sub.a is hydrogen or alkyl and R.sub.a is hydrogen, or unsubstituted or fluorine-substituted alkyl; or an .alpha.-amino acid of Formula .sub.Via, ##STR00042## wherein R.sub.a is hydrogen, or unsubstituted or fluorine-substituted alkyl; R.sup.1.sub.a is hydrogen, alkyl, phenyl, or substituted phenyl; or R.sub.a and R.sup.1.sub.a together form a propylene bridge; and X.sub.a is hydroxy, alkoxy or fluorine; or an .alpha.-amino acid of Formula VII.sub.a, ##STR00043## wherein R.sub.a is hydrogen, or unsubstituted or fluorine-substituted alkyl; R.sup.1.sub.a is hydrogen, alkyl, phenyl, or substituted phenyl; or R.sub.a and R.sup.1.sub.a together form a propylene bridge; and R.sup.2.sub.a, R.sup.3.sub.a, R.sup.4.sub.a and R.sup.5.sub.a are each, independently, hydrogen or alkyl; or an .alpha.-amino acid residue of Formula VIII.sub.a, ##STR00044## wherein R.sub.a is hydrogen, or unsubstituted or fluorine-substituted alkyl; or a 2-azabicyclo[2.2.1]heptane-3-carboxylic acid derivative of Formula IX.sub.a, ##STR00045## wherein the 3-carbonyl moiety is in the endo or exo position, Z.sub.a is a single bond or a double bond, and R.sub.a is hydrogen or unsubstituted or fluorine-substituted alkyl; or an .alpha.-amino acid residue of Formula X.sub.a, ##STR00046## wherein n.sub.a is 1, 2 or 3, and R.sup.7.sub.a is hydrogen or alkyl and R.sub.a is hydrogen, unsubstituted alkyl or fluorine-substituted alkyl; B is a valyl, isoleucyl, allo-isoleucyl, norvalyl, 2-tert-butylglycyl or 2-ethylglycyl residue; or an .alpha.-amino acid residue of Formula II.sub.b, ##STR00047## wherein R.sup.1.sub.b is hydrogen, and R.sup.2.sub.b is alkyl or alkenyl; or R.sup.1.sub.b and R.sup.2.sub.b together form an isopropylidene group; D is an N-alkylvalyl, N-alkyl-2-ethylglycyl, N-alkyl-2-tert-butylglycyl, N-alkylnorleucyl, N-alkylisoleucyl, N-alkyl-allo-isoleucyl or N-alkylnorvalyl residue; or an .alpha.-amino acid residue of Formula II.sub.d, ##STR00048## wherein R.sub.d is hydrogen, or unsubstituted or fluorine-substituted alkyl; R.sup.1.sub.d is hydrogen; and R.sup.2.sub.d is alkyl, substituted alkyl or alkenyl; or R.sup.1.sub.d and R.sup.2.sub.d together form an isopropylidene group; or an .alpha.-amino acid residue of Formula III.sub.d, ##STR00049## wherein n.sub.d is 1 or 2; R.sup.3.sub.d is hydrogen, alkyl or fluorine-substituted alkyl; and X.sub.d is hydrogen; or n.sub.d is 1 and X.sub.d is fluorine, hydroxy, methoxy, or ethoxy; E is a prolyl, thiazolidinyl-4-carbonyl, homoprolyl, or hydroxyprolyl residue; or an .alpha.-amino acid residue of Formula II.sub.e, ##STR00050## wherein n.sub.e is 0, 1 or 2, R.sup.1.sub.e is hydrogen, or unsubstituted or fluorine-substituted alkyl; R.sup.2.sub.e and R.sup.3.sub.e are each, independently, hydrogen or alkyl; R.sup.4.sub.e is hydrogen, hydroxy or alkoxy; and R.sup.5.sub.e is hydrogen or fluorine; or n.sub.e is 1 and R.sup.3.sub.e and R.sup.4.sub.e together form a double bond; or n.sub.e is 1 and R.sup.4.sub.e and R.sup.5.sub.e together form a double-bonded oxygen diradical; or n.sub.e is 1 or 2 and R.sup.1.sub.e and R.sup.2.sub.e together form a double bond; or an aminocyclopentanecarboxylic acid residue of Formula III.sub.e, ##STR00051## wherein R.sub.e is alkyl and R.sup.1.sub.e is hydrogen, or unsubstituted or fluorine-substituted alkyl; F is a prolyl, thiazolidinyl-4-carbonyl, homoprolyl or hydroxyprolyl residue; or an .alpha.-amino acid residue of Formula II.sub.f, ##STR00052## wherein n.sub.f is 0, 1 or 2, R.sup.1.sub.f is hydrogen, or unsubstituted or fluorine-substituted alkyl; R.sup.2.sub.f and R.sup.3.sub.f are each, independently, hydrogen or methyl; R.sup.4.sub.f is hydrogen, hydroxy, alkoxy, or fluorine; R.sup.5.sub.f is hydrogen or fluorine; or n.sub.f is 1 and R.sup.3.sub.f and R.sup.4.sub.f together form a double bond; or n.sub.f is 1 and R.sup.4.sub.f and R.sup.5.sub.f together form a double-bonded oxygen diradical; or n.sub.f is 1 or 2 and R.sup.1.sub.f and R.sup.2.sub.f together form a double bond; or a 2- or 3-aminocyclopentanecarboxylic acid residue of Formula III.sub.f, ##STR00053## wherein R.sub.f is alkyl and R.sup.1.sub.f is hydrogen, or unsubstituted or fluorine-substituted alkyl; or an N-alkylglycyl or N-alkylalanyl residue; G is an .alpha.-amino acid residue of Formula II.sub.g, ##STR00054## wherein R.sup.1.sub.g is hydrogen or alkyl and R.sup.2.sub.g is hydrogen, alkyl, arylalkyl, heteroarylalkyl, phenyl or substituted phenyl; or R.sup.1.sub.g and R.sup.2.sub.g, together with the .alpha.-carbon atom, form a C.sub.5 C.sub.6 ring or a benzo-fused C.sub.5 ring; K is an .alpha.-amino acid of Formula II.sub.k, ##STR00055## wherein R.sup.1.sub.k is hydrogen or alkyl; and R.sup.2.sub.k is hydrogen, alky, arylakyl, heteroarylalkyl, phenyl or substituted phenyl; or R.sup.1.sub.g and R.sup.2.sub.g, together with the .alpha.-carbon atom, form a cyclopentane ring or a benzo-fused cyclopentane ring; and L is a substituted or unsubstituted amino, hydrazido, aminoxy or oximato group provided that when s and r are each 0, and A is formula II.sub.a where n.sub.a is 0 or 1 R.sup.1.sub.a, R.sup.2.sub.a, R.sup.3.sub.a, R.sup.4.sub.a, and R.sup.5.sub.a are each hydrogen, the L is a substituted or unsubstituted amino or hydrazido group.

Description

BACKGROUND OF THE INVENTION

A number of short peptides with significant activity as inhibitors of cell growth have been isolated from the Indian Ocean sea hare Dolabella auricularia (Bai et al., Biochem. Pharmacology,40: 1859 1864 (1990); Beckwith et al., J. Natl. Cancer Inst., 85: 483 488 (1993) and references cited therein). These include Dolastatins 1 10 (U.S. Pat. No. 4,816,444, issued to Pettit et al.) and Dolastatin-15 (European Patent Application No. 398558). Dolastatin 15, for example, markedly inhibits the growth of the National Cancer Institute's P388 lymphocytic leukemia (PS system) cell line, a strong predictor of efficacy against various types of human malignancies.

The exceedingly small amounts of the various Dolastatin peptides present in Dolabella auricularia (about 1 mg each per 100 kg sea hare) and the consequent difficulties in purifying amounts sufficient for evaluation and use, have motivated efforts toward the synthesis of these compounds (Roux et al., Tetrahedron 50: 5345 5360 (1994); Shioiri et al., Tetrahedron 49: 1913 24 (1993); Patino et al., Tetrahedron 48: 4115 4122 (1992) and references cited therein). Synthetic Dolastatin 15, however, suffers from drawbacks which include poor solubility in aqueous systems and the need for expensive starting materials for its synthesis. These, in turn, have led to the synthesis and evaluation of structurally modified Dolastatin 15 derivatives [cf.: Biorg. Med. Chem. Lett. 4: 1947 50 (1994); WO 93 03054; JP-A-06234790; WO 93 23424].

However, there is a need for synthetic compounds with the biological activity of Dolastatin 15 which have useful aqueous solubility and can be produced efficiently and economically.

SUMMARY OF THE INVENTION

Compounds of the present invention include cell growth inhibitors which are peptides of Formula I, A-B-D-E-F-(G).sub.r-(K).sub.s-L (I), and acid salts thereof, wherein A, B, D, E, F, G and K are .alpha.-amino acid residues, and s and r are each, independently, 0 or 1. L is a monovalent radical, such as, for example, an amino group, an N-substituted amino group, a .beta.-hydroxylamino group, a hydrazido group, an alkoxy group, a thioalkoxy group, an aminoxy group, or an oximato group.

Another aspect of the present invention includes pharmaceutical compositions comprising a compound of Formula I and a pharmaceutically acceptable carrier.

An additional embodiment of the present invention is a method for treating cancer in a mammal, such as a human, comprising administering to the mammal an effective amount of a compound of Formula I in a pharmaceutically acceptable composition.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to peptides having antineoplastic activity. It also includes pharmaceutical compositions comprising these compounds and methods for treating cancer in a mammal, including a human, by administration of these compositions to the mammal.

Dolastatin 15, a peptide isolated from the sea hare Dolabella auricularia, is a potent inhibitor of cell growth. This compound, however, is present in trace quantities in the sea hare, and is thus difficult to isolate. Dolastatin 15 is also expensive to synthesize and suffers from poor aqueous solubility. As shown herein, however, Dolastatin 15 can serve as a starting point for the development of compounds which overcome these disadvantages while retaining antineoplastic activity or exhibiting greater antineoplastic activity than the natural product. Applicants have discovered that certain structural modifications of Dolastatin 15 provide compounds with a surprisingly improved therapeutic potential for the treatment of neoplastic diseases as compared to Dolastatin 10 and Dolastatin 15. Furthermore, the compounds of the present invention can be conveniently synthesized, as described below in detail.

For the purposes of the present invention, the term "monovalent radical" is intended to mean an electrically neutral molecular fragment capable of forming one covalent bond with a second neutral molecular fragment. Monovalent radicals include the hydrogen atom, alkyl groups, such as methyl, ethyl and propyl groups, halogen atoms, such as fluorine, chlorine and bromine atoms, aryl groups, such as phenyl and naphthyl groups, and alkoxy groups, such as methoxy and ethoxy groups. Two monovalent radicals on adjacent sigma-bonded atoms can also together form a pi bond between the adjacent atoms. Two monovalent radicals may also be linked together, for example, by a polymethylene unit, to form a cyclic structure. For example, the unit --N(R)R', wherein R and R' are each a monovalent radical, can, together with the nitrogen atom, form a heterocyclic ring. In addition, two monovalent radicals bonded to the same atom can together form a divalent radical, such as an oxygen atom or an alkylidene group, for example, a propylidene group.

For the purposes of the present invention, the term "normal alkyl" refers to an unbranched, or straight chain, alkyl group, for example, normal propyl (n-propyl, --CH.sub.2CH.sub.2CH.sub.3).

The compounds of the present invention can be represented by Formula I, A-B-D-E-F-(G).sub.r-(K).sub.s-L (I), wherein A, B, D, E, F, G, and K are .alpha.-amino acid residues; s and r are each, independently, 0 or 1; and L is a monovalent radical such as an amino group, an N-substituted amino group, a .beta.-hydroxylamino group, a hydrazido group, an alkoxy group, a thioalkoxy group, an aminoxy group, or an oximato group.

The peptides of Formula I are generally composed of L-amino acids but they can contain one or more D-amino acids. In the following discussion, reference to a particular amino acid includes both enantiomers unless a specific enantiomer is indicated. The present compounds can also be present as salts with physiologically-compatible acids, including hydrochloric acid, citric acid, tartaric acid, lactic acid, phosphoric acid, methanesulfonic acid, acetic acid, formic acid, maleic acid, fumaric acid, malic acid, succinic acid, malonic acid, sulfuric acid, L-glutamic acid, L-aspartic acid, pyruvic acid, mucic acid, benzoic acid, glucuronic acid, oxalic acid, ascorbic acid and acetylglycine.

The following is a description of the present invention, including a detailed description of individual components and of methods of using the claimed compounds.

Compounds of the Present Invention

Identity of A

In one embodiment, A is a proline derivative of Formula II.sub.a,

##STR00001## where n.sub.a is an integer, preferably 0, 1, 2, or 3. R.sub.a is a monovalent radical, such as a hydrogen atom or an unsubstituted or fluorine-substituted alkyl group, for example a normal, branched or cyclic C.sub.1 C.sub.3-alkyl group which is, optionally, substituted by from 1 to about 3 fluorine atoms; suitable examples include methyl, ethyl, isopropyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, 1-methyl-2-fluoroethyl, 1-fluoromethyl-2-fluoroethyl or cyclopropyl; methyl, ethyl or isopropyl are preferred;

In this embodiment, R.sup.1.sub.a is a monovalent radical, such as a hydrogen atom, an alkyl group, such as a methyl, ethyl or propyl group, or a phenyl group. The phenyl group can be substituted; suitable substituents include one or more halogen atoms, with fluorine, chlorine and bromine atoms preferred, C.sub.1 C.sub.4-alkyl groups, methoxy, ethoxy, trifluoromethyl or nitro groups. R.sub.a and R.sup.1.sub.a together can also form a propylene bridge.

R.sup.2.sub.a, R.sup.3.sub.a, R.sup.4.sub.a and R.sup.5.sub.a are each, independently, a monovalent radical, such as a hydrogen atom or an alkyl, preferably, methyl, group.

In another embodiment, A is a substituted glycine derivative of Formula III.sub.a,

##STR00002## where R.sub.a has the meaning stated for R.sub.a in Formula II.sub.a and, R.sup.1.sub.a is a monovalent radical, for example, a hydrogen atom or a C.sub.1 C.sub.6-alkyl group, preferably a methyl, ethyl or propyl group.

In this embodiment, R.sup.6.sub.a is a monovalent radical, such as an alkyl, substituted alkyl, alkenyl, phenyl or substituted phenyl group. Suitable examples include methoxymethyl, 1-methoxyethyl, 1,1-dimethyl-hydroxymethyl, 1-trifluoromethylethyl, 1-trifluoromethyl-2,2,2-trifluoroethyl, vinyl, and 1-methylvinyl. Phenyl substituents can include one or more halogen atoms, preferably fluorine, chlorine or bromine atoms, and alkyl, methoxy, ethoxy, trifluoromethyl, and nitro groups.

When R.sup.1.sub.a is an alkyl group, R.sup.6.sub.a can also be a C.sub.1 C.sub.6-alkyl, cycloalkyl, unsubstituted benzyl or substituted benzyl group. Suitable benzyl substituents include one or more halogen atoms, such as fluorine, chlorine or bromine atoms, C.sub.1 C.sub.4-alkyl groups, and methoxy, ethoxy, trifluoromethyl and nitro groups.

R.sup.7.sub.a is a monovalent radical, preferably a methyl, ethyl or isopropyl group.

In another embodiment, A is an .alpha.-amino acid derivative of Formula IV.sub.a,

##STR00003## where m.sub.a is an integer, preferably 1 or 2, and R.sub.a and R.sup.7.sub.a have the meanings stated for these substituents in Formula III.sub.a.

In another embodiment, A is an .alpha.-amino acid derivative of Formula V.sub.a,

##STR00004## where R.sub.a and R.sup.7.sub.a have the meanings stated for R.sub.a and R.sup.7.sub.a in Formula III.sub.a.

In a further embodiment, A is a substituted proline derivative of Formula VI.sub.a,

##STR00005## where R.sub.a and R.sup.1.sub.a have the meanings stated for R.sub.a and R.sup.1.sub.a in Formula II.sub.a, and X.sub.a is a monovalent radical, preferably a hydroxyl, alkoxy, for example, methoxy or ethoxy, group or a fluorine atom.

In another embodiment, A is a thiaprolyl derivative of Formula VII.sub.a,

##STR00006## where R.sub.a, R.sup.1.sub.a, R.sup.2.sub.a, R.sup.3.sub.a, R.sup.4.sub.a and R.sup.5.sub.a have the meanings stated for the respective substituents in Formula II.sub.a.

In another embodiment, A is a 1,3-dihydroisoindole derivative of Formula VIII.sub.a

##STR00007## where R.sub.a has the meaning stated for R.sub.a for Formula II.sub.a.

In another embodiment, A is a 2-azabicyclo[2.2.1]heptane-3-carboxylic acid derivative of Formula IX.sub.a,

##STR00008## where Z.sub.a is a single or double bond and R.sub.a has the meaning stated for Formula II.sub.a. The 3-carbonyl substituent can have either the exo or endo orientation.

In another embodiment, A is an .alpha.-amino acid derivative of Formula X.sub.a,

##STR00009## where n.sub.a has the meaning as stated for n.sub.a for Formula II.sub.a, and R.sup.7.sub.a and R.sub.a have the meanings as stated for R.sup.7.sub.a and R.sub.a for Formula III.sub.a. Identity of B

B is a valyl, isoleucyl, allo-isoleucyl, norvalyl, 2-tert-butylglycyl or 2-ethylglycyl residue. B can also be an .alpha.-amino acid residue of Formula II.sub.b,

##STR00010## in which R.sup.1.sub.b and R.sup.2.sub.b are each a monovalent radical. R.sup.1.sub.b is, preferably, a hydrogen atom and R.sup.2.sub.b is, for example, an alkyl, alkoxyalkyl or alkenyl group. In preferred embodiments, R.sup.2.sub.b is a cyclopropyl group, a normal or branched butyl, preferably tertiary-butyl, group, a methoxymethyl group, a 1-methoxyethyl group or a 1-methylvinyl group. Additionally, R.sup.1.sub.b and R.sup.2.sub.b together can be an isopropylidene group. Identity of D

D is an N-alkylvalyl, N-alkyl-2-ethylglycyl, N-alkyl-2-tert-butylglycyl, N-alkyl-norleucyl, N-alkyl-isoleucyl, N-alkyl-allo-isoleucyl or N-alkyl-norvalyl residue, where the N-alkyl group is preferably a methyl group or an ethyl group.

In another embodiment, D is an .alpha.-amino acid residue of Formula II.sub.d,

##STR00011## where R.sub.d has the meaning stated for R.sub.a in Formula III.sub.a, R.sup.1.sub.d is a monovalent radical, preferably a hydrogen atom, and R.sup.2.sub.d is a monovalent radical, for example, an alkyl, alkoxyalkyl or alkenyl group. In preferred embodiments, R.sup.2.sub.d is a cyclopropyl group, a normal or branched butyl, preferably tertiary-butyl, group, a methoxymethyl group, a 1-methoxyethyl group or a 1-methylvinyl group, such as a cyclopropyl group, a methoxymethyl group, a 1-methoxyethyl group or a 1-methylvinyl group. Additionally, R.sup.1.sub.d and R.sup.2.sub.d together can form an isopropylidene group.

Alternatively, D can be a proline derivative of Formula III.sub.d,

##STR00012## where n.sub.d is an integer, for example, 1 or 2, and R.sup.3.sub.d has the meaning stated for R.sup.1.sub.a in Formula III.sub.a. X.sub.d is a monovalent radical, preferably a hydrogen atom, and, in the case where n.sub.d equals 1, can also be a hydroxy or alkoxy, for example, methoxy or ethoxy, group or a fluorine atom. Identity of E

E is a prolyl, thiazolidinyl-4-carbonyl, homoprolyl or hydroxyprolyl residue, or a cyclic .alpha.-amino carboxylic acid residue of Formula II.sub.e,

##STR00013## where n.sub.e is an integer, preferably 0, 1 or 2. R.sup.1.sub.e has the meaning stated for R.sup.1.sub.a in Formula III.sub.a. R.sup.2.sub.e and R.sup.3.sub.e are each a monovalent radical, and can be, independently, a hydrogen atom or an alkyl, preferably methyl, group. R.sup.4.sub.e, is a monovalent radical, preferably a hydrogen atom, a hydroxy, alkoxy, for example, methoxy or ethoxy, group or a fluorine atom. R.sup.5.sub.e is a monovalent radical, preferably a hydrogen atom or a fluorine atom. In the case where n.sub.e is 1, R.sup.3.sub.e and R.sup.4.sub.e can together form a double bond, or R.sup.4.sub.e and R.sup.5.sub.e can together be a double-bonded oxygen radical. In the case where n.sub.e has the value 1 or 2, R.sup.1.sub.e and R.sup.2.sub.e can together form a double bond.

In another embodiment, E is a 2- or 3-amino-cyclopentanecarboxylic acid residue of Formula III.sub.e,

##STR00014## where R.sub.e is an alkyl group, such as methyl or ethyl, and R.sup.1.sub.e has the meaning stated for R.sup.1.sub.a in Formula III.sub.a. Identity of F

F is a prolyl, thiazolidinyl-4-carbonyl, homoprolyl or hydroxyprolyl residue. F can also be a cyclic .alpha.-amino acid residue of Formula II.sub.f,

##STR00015## where n.sub.f is an integer, preferably 0, 1 or 2. R.sup.1.sub.f has the meaning stated for R.sup.1.sub.a in Formula III.sub.a. R.sup.2.sub.f and R.sup.3.sub.f are each a monovalent radical, and can be, independently, a hydrogen atom or an alkyl, preferably methyl, group. R.sup.4.sub.f is a monovalent radical, preferably a hydrogen atom, a hydroxy, alkoxy, for example, methoxy or ethoxy, group or a fluorine atom. R.sup.5.sub.f is a monovalent radical, preferably a hydrogen atom or a fluorine atom. In the case where n.sub.f has the value 1, R.sup.3.sub.f and R.sup.4.sub.f together can form a double bond or R.sup.4.sub.f and R.sup.5.sub.f can together be a double-bonded oxygen radical. In the case where n.sub.f has the value 1 or 2, R.sup.1.sub.f and R.sup.2.sub.f can together form a double bond.

In another embodiment, F is a 2- or 3-amino-cyclopentanecarboxylic acid residue of Formula III.sub.f

##STR00016## where R.sub.f is a monovalent radical, such as a methyl or ethyl group, and R.sup.1.sub.f has the meaning stated for R.sup.1.sub.a in Formula III.sub.a.

In another embodiment, F is an N-alkylglycyl or N-alkylalanyl residue, and the alkyl group is, preferably, a methyl group or an ethyl group.

Identity of G

G is an .alpha.-amino acid residue of Formula II.sub.g,

##STR00017## wherein R.sup.1.sub.g is a hydrogen atom, or an alkyl group, for example, methyl, ethyl or n-propyl. R.sup.2.sub.g can be, for example, a hydrogen atom, or an alkyl, arylalkyl, heteroarylalkyl or aryl group. Preferably, R.sup.2.sub.g is an ethyl, isopropyl, tert-butyl, isobutyl, 2-methylpropyl, cyclohexylmethyl, benzyl, thiazolyl-2-methyl, pyridyl-2-methyl, n-butyl, 2,2-dimethylpropyl, naphthylmethyl, or n-propyl group, or a substituted or unsubstituted phenyl group. Suitable phenyl substituents include one or more halogen, preferably fluorine, chlorine or bromine, atoms, C.sub.1 C.sub.4-alkyl groups, methoxy, ethoxy, nitro or trifluoromethyl groups or a dioxomethylene group. Alternately, R.sup.1.sub.g and R.sup.2.sub.g can, together with the .alpha.-carbon atom, form a cyclopentane or cyclohexane ring or a benzo-fused cyclopentane ring, such as, for example, the indanyl group. Identity of K

K is an .alpha.-amino acid residue of Formula II.sub.k,

##STR00018## wherein R.sup.1.sub.k has the identity stated for R.sup.1.sub.g in Formula II.sub.g, and R.sup.2.sub.k has the identity stated for R.sup.2.sub.g in Formula II.sub.g. Identity of L

In one embodiment, L is an amino or substituted amino group of Formula II.sub.l,

##STR00019## where R.sup.1.sub.l is a monovalent radical, such as a hydrogen atom, a normal or branched, saturated or unsaturated C.sub.1 C.sub.18-alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aryl-C.sub.1 C.sub.6-alkoxy group, or a substituted or unsubstituted aryloxy-C.sub.1 C.sub.6- alkoxy or heteroaryl-C.sub.1 C.sub.6-alkoxy group. The aryl group is preferably a phenyl or naphthyl group. The heteroaryl group is a 5- or 6-membered, preferably nitrogen-, oxygen- or sulfur-containing, ring system, such as, for example, a heteroaryl group derived from imidazole, isoxazole, isothiazole, thiazole, oxazole, pyrazole, thiophene, furan, pyrrole, 1,2,4- or 1,2,3-triazole, pyrazine, indole, benzofuran, benzothiophene, indole, isoindole, indazole, quinoline, pyridazine, pyrimidine, benzimidazole, benzopyran, benzothiazole, oxadiazole, thiadiazole or pyridine. Suitable aryl substituents include one or more halogen, preferably fluorine, bromine or chlorine, atoms, C.sub.1 C.sub.4-alkyl groups, methoxy, ethoxy or trifluoromethyl groups, a dioxymethylene group or nitro groups.

R.sup.2.sub.l is a monovalent radical, such as a hydrogen atom, a normal or branched, saturated or unsaturated C.sub.1 C.sub.18-alkyl group, a C.sub.3 C.sub.10-cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. The aryl group is preferably a phenyl or naphthyl group. The heteroaryl group is a 5- or 6-membered, preferably nitrogen-, oxygen- or sulfur- containing, ring system, such as, for example, a heteroaryl group derived from imidazole, isoxazole, isothiazole, thiazole, oxazole, pyrazole, thiophene, furan, pyrrole, 1,2,4- or 1,2,3-triazole, pyrazine, indole, benzofuran, benzothiophene, indole, isoindole, indazole, quinoline, pyridazine, pyrimidine, benzimidazole, benzopyran, benzothiazole, oxadiazole, thiadiazole or pyridine. Suitable aryl substituents include one or more halogen, preferably fluorine, bromine or chlorine, atoms, C.sub.1 C.sub.4-alkyl groups, methoxy, ethoxy or trifluoromethyl groups, a dioxymethylene group or nitro groups.

R.sup.2.sub.l can, alternately, be of Formula II.sub.r,

##STR00020## where a.sub.l is an integer, such as 0, 1, 2, 3, 4 or 5. R.sup.3.sub.l is a monovalent radical, preferably a lower alkyl group, such as a methyl, ethyl, propyl or isopropyl group. R.sup.4.sub.l is a monovalent radical, which can be a saturated or partially unsaturated carbocyclic system comprising from about 3 to about 10 carbon atoms, a substituted or unsubstituted aryl or heteroaryl group, with aryl and heteroaryl and preferred substituents having the meaning stated for R.sup.2.sub.l in Formula II.sub.l.

R.sup.2.sub.l can also be a substituent of Formula III.sub.r, --(CH.sub.2).sub.2--W.sub.l--R.sup.5.sub.l (III.sub.r), wherein W.sub.l is an oxygen or sulfur atom or an N--R.sup.6.sub.l group. R.sup.5.sub.l is a monovalent radical, such as a hydrogen atom, a C.sub.1 C.sub.4-alkyl or C.sub.3 C.sub.7-cycloalkyl group or a substituted or unsubstituted aryl or arylmethyl group, with aryl and its preferred substituents having the meaning stated for R.sup.2.sub.l from Formula II.sub.l. R.sup.6.sub.l is a monovalent radical, preferably a hydrogen atom, a C.sub.1 C.sub.4-alkyl group or a C.sub.3 C.sub.7-cycloalkyl group, a C.sub.1 C.sub.18-alkanoyl group, a benzoyl group or a substituted or unsubstituted aryl or arylmethyl group, with aryl and its preferred substituents having the meaning stated for R.sup.2.sub.l in Formula II.sub.l.

R.sup.2.sub.l can, alternately, be a substituent of Formula IV.sub.r, --(CH.sub.2).sub.b.sub.l--Z.sub.l (IV.sub.r), where b.sub.l is an integer, preferably 2, 3 or 4. Z.sub.l can be a monovalent radical such as a formyl, aminocarbonyl or hydrazinocarbonyl group, or a cyclic or acyclic acetal or thioacetal group.

R.sup.2.sub.l can also be a substituent of Formula V.sub.r,

##STR00021## in which b.sub.l has the above-mentioned meaning. R.sup.7.sub.l can be a monovalent radical, such as a polyglycol group of the formula --O--(CH.sub.2--CH.sub.2--O).sub.d.sub.l--CH.sub.3, where d.sub.l is an integer, preferably in the range from about 2 to about 4 or from about 40 to about 90.

R.sup.2.sub.l can further be a carbohydrate of Formula VI.sub.r,

##STR00022## where R.sup.8.sub.l is a monovalent radical, such as a hydrogen atom, a C.sub.1 C.sub.4-alkanoyl or alkyl group, a benzoyl group or a benzyl group.

L can also be a .beta.-hydroxylamino group of Formula III.sub.l,

##STR00023## where R.sup.9.sub.l is a monovalent radical such as a hydrogen atom, a C.sub.1 C.sub.6-alkyl group or a substituted or unsubstituted aryl group, with aryl and its preferred substituents having the meaning stated for R.sup.2.sub.l. R.sup.10.sub.l is a monovalent radical, preferably a hydrogen atom, alkyl, for example, methyl, or a phenyl group.

When r and/or s is 1, L can also be an amino group of Formula IV.sub.l,

##STR00024## where R.sup.2.sub.l and R.sup.4.sub.l are each a monovalent radical. R.sup.2.sub.l and R.sup.4.sub.l can also be linked by a carbon-carbon bond.

Another subclass of compounds of this invention includes peptides of Formula I wherein L is a hydrazido group of Formula V.sub.l,

##STR00025## and R.sup.11.sub.l is a monovalent radical, preferably a hydrogen atom. R.sup.12.sub.l can be a monovalent radical such as a hydrogen atom, a normal or branched C.sub.1 C.sub.8-alkyl group, a C.sub.3 C.sub.8-cycloalkyl group, a C.sub.3 C.sub.8-cycloalkyl-C.sub.1 C.sub.4-alkyl group or a substituted or unsubstituted aryl, heteroaryl, aryl-C.sub.1 C.sub.4-alkyl or heteroaryl-C.sub.1 C.sub.4-alkyl group, where aryl, heteroaryl and their preferred substituents can be selected from among the options listed for R.sup.2.sub.l.

When r and/or s is 1, R.sup.11.sub.l can also be selected from among the options listed above for R.sup.12.sub.l, and the two radicals together can additionally form a propylene or butylene bridge.

Another subclass of compounds of this invention includes peptides of Formula I wherein L is a monovalent radical of the formula --O--R.sup.13.sub.l or the formula --S--R.sup.13.sub.l, where R.sup.13.sub.l is a monovalent radical, such as a C.sub.3 C.sub.10-cycloalkyl group, a normal or branched C.sub.2 C.sub.16-alkenylmethyl group or a C.sub.1 C.sub.16-alkyl group which can be substituted by from 1 to about 5 halogen, preferably fluorine, atoms.

R.sup.13.sub.l can also be the radical --(CH.sub.2).sub.e--R.sup.14.sub.l, where e is an integer, preferably 1, 2 or 3. R.sup.14.sub.l is a monovalent radical, preferably a saturated or partially unsaturated C.sub.3 C.sub.10-carbocycle.

R.sup.13.sub.l can further be the monovalent radical --[CH.sub.2--CH.dbd.C(CH.sub.3)--CH.sub.2].sub.f--H, where f is an integer, preferably 1, 2, 3 or 4.

R.sup.13.sub.l can also be the radical --[CH.sub.2--CH.sub.2--O].sub.g--CH.sub.3, where g is an integer, preferably in the range from 1 to about 5.

R.sup.13.sub.l can also be the radical --(CH.sub.2).sub.h-aryl or --(CH.sub.2).sub.h-heteroaryl, where aryl and heteroaryl can also be substituted and, along with their preferred substituents, can be selected from the group listed for R.sup.2.sub.l. h is an integer, preferably 0, 1, 2 or 3.

R.sup.13.sub.l can further be the radical --(CH.sub.2).sub.b--W.sub.l--R.sup.5.sub.l. b, W.sub.l and R.sup.5.sub.l can each be selected from among the options described for Formula IV.sub.l.

Another subclass of compounds of this invention includes peptides of Formula I in which L is an aminoxy group of the formula --O--N(R.sup.15.sub.l)(R.sup.16.sub.l), where R.sup.15.sub.l and R.sup.16.sub.l are each a monovalent radical, which can independently be a hydrogen atom, a normal or branched C.sub.1 C.sub.8-alkyl group, which can be substituted by halogen, preferably fluorine, atoms, a C.sub.3 C.sub.8-cycloalkyl group, a C.sub.3 C.sub.8-cycloalkyl-C.sub.1 C.sub.4-alkyl group, a substituted or unsubstituted aryl or heteroaryl group or a substituted or unsubstituted aryl-C.sub.1 C.sub.4-alkyl group. Aryl and heteroaryl groups and the preferred substituents thereof can be selected from the options listed for R.sup.2.sub.l. R.sup.16.sub.l can be selected from among the options listed for R.sup.15.sub.l. Additionally, R.sup.15.sub.l and R.sup.16.sub.l can together form a 5-, 6- or 7-membered heterocycle. The compounds of the present invention further comprise the salts of the compounds described above with physiologically tolerated acids.

Another subclass of compounds of this invention includes peptides of Formula I wherein L is an oximato group of the formula --O--N.dbd.C(R.sup.15.sub.l)(R.sup.16.sub.l), R.sup.15.sub.l and R.sup.16.sub.l can be selected from among the options listed above and, additionally, can together form a cyclic system comprising, preferably, from about 3 to about 7 ring atoms. This cyclic system can additionally be fused to one or more aromatic rings. Particularly preferred cyclic systems are shown below.

##STR00026## ##STR00027##

In one embodiment, the invention provides compounds of Formula I wherein A is an amino acid derivative selected from among N-alkyl-D-prolyl, N-alkyl-L-prolyl, N-alkyl-D-piperidine-2-carbonyl, N-alkyl-L-piperidine-2-carbonyl, N,N-dialkyl-D-2-ethyl-2-phenylglycyl and N,N-dialkyl-L-2-ethyl-2-phenylglycyl, wherein alkyl is methyl, ethyl or isopropyl; and B is a valyl, isoleucyl or 2-t-butyl-L-glycyl residue.

Preferred compounds of the invention include compounds of Formula I wherein r and s are each 0. A is an amino acid derivative selected from among D-N-methyl-piperidine-2-carbonyl, L-N-methyl-piperidine-2-carbonyl, N,N-dimethylamino-iso-butyryl, N-methyl-L-prolyl, N-methyl-L-thiazolidine-4-carbonyl, N,N-dimethyl-glycyl, L-prolyl, L-piperidine-2-carbonyl, N-propyl-D-piperidine-2-carbonyl, D-piperidine-2-carbonyl, N-ethyl-D-piperidine-2-carbonyl, N-methyl-[2,2,5,5-tetramethyl]-L-thiazolidine-2-carbonyl, N-isopropyl-D-piperidine-2-carbonyl, N,N-dimethyl-2-cyclopropylglycyl, N,N-dimethyl-L-2-ethyl-2-phenylglycyl, N,N-dimethyl-D-2-ethyl-2-phenylglycyl, D-prolyl, N-methyl-D-prolyl, N,N-dimethyl-2-(2-fluorophenyl)glycyl, 1-aza-[3,3,0]bicyclooctyl-5-carbonyl, N,N-dimethyl-2-[4-fluoro]phenyl-glycyl, N-methyl-[2,2,5,5-tetramethyl]-thiazolidine-2-carbonyl, 2-(R,S)-ethyl-2-phenylglycyl, D,L-1-aminoindane-1-carbonyl, N,N-dimethyl-2-(R,S)-methyl-2-phenylglycyl, 2-[N,N-dimethylamino]indane-2-carbonyl, 5-[N,N-dimethylamino]-5,6,7,8-tetrahydro-naphthalene-5-carbonyl, N-isopropyl-2-(R,S)-ethyl-2-phenylglycyl, 1-[N,N-dimethyl-amino]indane-2-carbonyl, N,N-dimethyl-2-propyl-2-phenylglycyl, N,N-dimethyl-2-[4-methoxy]phenyl-glycyl, N-methyl-3-hydroxy-D,L-valyl, N,N-dimethyl-D,L-2-isopropyl-2-phenylglycyl, N-methylpiperidine-2-carbonyl, N-methyl-L-prolyl, N-methyl-1,2,3,4-tetrahydroisoquinoline-1-carbonyl, N-methylazetidine-2-carbonyl, N-isopropylazetidine-2-carbonyl, N,N-dimethyl-[O-methyl]seryl, N,N-dimethyl-[O-methyl]threonyl, N-methyl-1,2,3,4-tetrahydroisoquinoline-3-carbonyl, 1-[N,N-dimethylamino]cyclohexyl-1-carbonyl, 1-[N,N-dimethylamino]cyclopentyl-1-carbonyl and 1,2,3,4-tetrahydroisoquinoline-3-carbonyl. B is valyl, isoleucyl or 2-tert-butylglycyl. D is N-methylvalyl, N-methyl-2-t-butylglycyl or N-methylisoleucyl. E and F are each, independently, prolyl, thiaprolyl, homoprolyl, hydroxyprolyl, 3,4-didehydroprolyl, 4-fluoroprolyl, and 3-methylprolyl. L is an alkoxy group or an amino group of the formula R.sup.1.sub.l--N--R.sup.2.sub.l, wherein R.sup.1.sub.l and R.sup.2.sub.l are independently selected from the group consisting of hydrogen, alkoxy, hydroxy, alkyl and alkylaryl.

In a particularly preferred subset of the compounds of the invention, r and s are each 0. A is an amino acid derivative selected from among D-N-methyl-piperidine-2-carbonyl, N-ethyl-D-piperidine-2-carbonyl, N-isopropyl-D-piperidine-2-carbonyl, N,N-dimethyl-2-cyclopropyl-glycyl, N-methyl-D-prolyl, 1-aza-[3,3,0]bicyclooctyl-5-carbonyl, N-methyl-[2,2,5,5-tetramethyl]-thiazolidine-2-carbonyl, 2-(R,S)-ethyl-2-phenylglycyl, D,L-1-aminoindane-1-carbonyl, N,N-dimethyl-2-(R,S)-methyl-2-phenylglycyl, 5-[N,N-dimethylamino]-5,6,7,8-tetrahydro-naphthalene-5-carbonyl, 1-[N,N-dimethylamino]indane-2-carbonyl, N,N-dimethyl-2-propyl-2-phenylglycyl, N,N-dimethyl-L-2-ethyl-2-phenylglycyl, N,N-dimethyl-D-2-ethyl-2-phenylglycyl, N-methyl-3-hydroxy-D,L-valyl, N,N-dimethyl-D,L-2-isopropyl-2-phenylglycyl, N-methyl-piperidine-2-carbonyl, N-methyl-D,L-prolyl, N-methyl-1,2,3,4-tetra-hydroisoquinoline-1-carbonyl, N-methylazetidine-2-carbonyl, N-isopropylazetidine-2-carbonyl, N,N-dimethyl-[O-methyl]seryl, 1-[N,N-dimethylamino]cyclohexyl-1-carbonyl and 1-[N,N-dimethylamino]cyclopentyl-1-carbonyl. B is valyl; D is N-methylvalyl; and E and F are each prolyl. L is a C.sub.1 C.sub.6-alkoxy group or an amino group of the formula R.sup.1.sub.l--N--R.sup.2.sub.l, wherein R.sup.1.sub.l and R.sup.2.sub.l are each independently selected from the group consisting of hydrogen, C.sub.1 C.sub.6-alkoxy, hydroxy, normal, cyclic or branched C.sub.1 C.sub.12-alkyl, and phenylalkyl.

Synthetic Methods

The compounds of the present invention can be prepared by known methods of peptide synthesis. Thus, the peptides can be assembled sequentially from individual amino acids or by linking suitable small peptide fragments. In sequential assembly, the peptide chain is extended stepwise, starting at the C-terminus, by one amino acid per step. In fragment coupling, fragments of different lengths can be linked together, and the fragments in turn can be obtained by sequential assembly from amino acids or by fragment coupling of still shorter peptides.

In both sequential assembly and fragment coupling it is necessary to link the units by forming an amide linkage, which can be accomplished via a variety of enzymatic and chemical methods. Chemical methods for forming the amide linkage are described in detail in standard references on peptide chemistry, including Muller, Methoden der organischen Chemie Vol. XV/2, 1 364, Thieme Verlag, Stuttgart, (1974); Stewart and Young, Solid Phase Peptide Synthesis, 31 34 and 71 82, Pierce Chemical Company, Rockford, Ill.(1984); Bodanszky et al., Peptide Synthesis, 85 128, John Wiley & Sons, New York, (1976). Preferred methods include the azide method, the symmetric and mixed anhydride method, the use of in situ generated or preformed active esters, the use of urethane protected N-carboxy anhydrides of amino acids and the formation of the amide linkage using coupling reagents, such as carboxylic acid activators, especially dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC), 1-ethoxycarbonyl-2- ethoxy-1,2-dihydroquinoline (EEDQ), pivaloyl chloride, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI), n-propanephosphonic anhydride (PPA), N,N-bis(2-oxo-oxazolidinyl)amidophosphoryl chloride (BOP-Cl), bromo-tris(pyrrolidino)phosphonium hexafluorophosphate (PyBrop), diphenyl-phosphoryl azide (DPPA), Castro's reagent (BOP, PyBop), O-benzotriazolyl-N,N,N',N'-tetramethyluronium salts (HBTU), O-azabenzotriazolyl-N,N,N',N'-tetramethyluronium salts (HATU), diethylphosphoryl cyanide (DEPCN), 2,5-diphenyl-2,3- dihydro-3-oxo-4-hydroxythiophene dioxide (Steglich's reagent; HOTDO), and 1,1'-carbonyldi-imidazole (CDI). The coupling reagents can be employed alone or in combination with additives such as N,N-dimethyl-4-aminopyridine (DMAP), N-hydroxy-benzotriazole (HOBt), N-hydroxyazabenzotriazole (HOAt), N-hydroxybenzotriazine (HOOBt), N-hydroxysuccinimide (HOSu) or 2-hydroxypyridine.

Although the use of protecting groups is generally not necessary in enzymatic peptide synthesis, reversible protection of reactive groups not involved in formation of the amide linkage is necessary for both reactants in chemical synthesis. Three conventional protective group techniques are preferred for chemical peptide synthesis: the benzyloxycarbonyl (Z), the t-butoxycarbonyl (Boc) and the 9-fluorenylmethoxy-carbonyl (Fmoc) techniques. Identified in each case is the protective group on the .alpha.-amino group of the chain-extending unit. A detailed review of amino-acid protective groups is given by Muller, Methoden der organischen Chemie Vol. XV/1, pp 20 906, Thieme Verlag, Stuttgart (1974). The units employed for assembling the peptide chain can be reacted in solution, in suspension or by a method similar to that described by Merrifield, J. Am. Chem. Soc. 85: (1963) 2149.

Solvents suitable for peptide synthesis include any solvent which is inert under the reaction conditions, especially water, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, dichloromethane (DCM), 1,4-dioxane, tetrahydrofuran (THF), N-methyl-2-pyrrolidone (NMP) and mixtures of these solvents.

Peptide synthesis on the polymeric support can be carried out in a suitable inert organic solvent in which the amino acid derivatives starting materials are soluble. However, preferred solvents additionally have resin- swelling properties, such as DMF, DCM, NMP, acetonitrile and DMS0, and mixtures of these solvents. Following synthesis, the peptide is removed from the polymeric support. The conditions under which this cleavage is accomplished for various resin types are disclosed in the literature. The cleavage reactions most commonly used are acid- or palladium-catalyzed, the former being conducted in, for example, liquid anhydrous hydrogen fluoride, anhydrous trifluoromethanesulfonic acid, dilute or concentrated trifluoroacetic acid, and acetic acid/dichloromethane/trifluoroethanol mixtures. The latter can be carried out in THF or THF-DCM-mixtures in the presence of a weak base, such as morpholine. Certain protecting groups are also cleaved off under these conditions.

Partial deprotection of the peptide may also be necessary prior to certain derivatization reactions. For example, peptides dialkylated at the N-terminus can be prepared by coupling the appropriate N,N-di-alkylamino acid to the peptide in solution or on the polymeric support, by reductive alkylation of the resin-bound peptide in DMF/1% acetic acid with NaCNBH.sub.3 and the appropriate aldehyde or by hydrogenation of the peptide in solution in the presence of the appropriate aldehyde or ketone and Pd/carbon.

The various non-naturally occurring amino acids as well as the various non-amino acid moieties disclosed herein can be obtained from commercial sources or synthesized from commercially available staring materials using methods known in the art. For example, amino acid building blocks with R.sup.1 and R.sup.2 groups can be prepared according to the method described by Wuensch and Weyl, Methoden der Organischen Chemie, vol. XV, Springer Verlag: Stuttgart, p. 306 (1974) and references cited therein.

Methods of Use of the Claimed Compounds

In another embodiment, the present invention comprises a method for partially or totally inhibiting formation of, or otherwise treating (e.g., reversing or inhibiting the further development of) solid tumors (e.g., tumors of the lung, breast, colon, prostate, bladder, rectum, or endometrial tumors) or hematological malignancies (e.g., leukemias, lymphomas) in a mammal, for example, a human, by administering to the mammal a therapeutically effective amount of a compound or a combination of compounds of Formula I. The compound(s) may be administered alone or in a pharmaceutical composition comprising the compound(s) and an acceptable carrier or diluent. Administration can be by any of the means which are conventional for pharmaceutical, preferably oncological, agents, including oral and parenteral means, such as subcutaneously, intravenously, intramuscularly and intraperitoneally, nasally or rectally. The compounds may be administered alone or in the form of pharmaceutical compositions containing a compound or compounds of Formula I together with a pharmaceutically accepted carrier appropriate for the desired route of administration. Such pharmaceutical compositions may be combination products, i.e., they may also contain other therapeutically active ingredients.

The dosage to be administered to the mammal, such as a human, will contain a therapeutically effective amount of a compound described herein. As used herein, "therapeutically effective amount" is an amount sufficient to inhibit (partially or totally) formation of a tumor or a hematological malignancy or to reverse development of a solid tumor or other malignancy or prevent or reduce its further progression. For a particular condition or method of treatment, the dosage is determined empirically, using known methods, and will depend upon factors such as the biological activity of the particular compound employed; the means of administration; the age, health and body weight of the recipient; the nature and extent of the symptoms; the frequency of treatment; the administration of other therapies; and the effect desired. A typical daily dose will be from about 0.05 to about 50 milligrams per kilogram of body weight by oral administration and from about 0.01 to about 20 milligrams per kilogram of body weight by parenteral administration.

The compounds of the present invention can be administered in conventional solid or liquid pharmaceutical administration forms, for example, uncoated or (film-)coated tablets, capsules, powders, granules, suppositories or solutions. These are produced in a conventional manner. The active substances can for this purpose be processed with conventional pharmaceutical aids such as tablet binders, fillers, preservatives, tablet disintegrants, flow regulators, plasticizers, wetting agents, dispersants, emulsifiers, solvents, sustained release compositions, antioxidants and/or propellant gases (cf. H. Sucker et al.: Pharmazeutische Technologie, Thieme-Verlag, Stuttgart, 1978). The administration forms obtained in this way typically contain from about 1 to about 90% by weight of the active substance.

The present invention will now be illustrated by the following examples, which are not limiting.

EXAMPLES

The proteinogenous amino acids are abbreviated in the examples using the known three-letter code. Other abbreviations employed are: TFA=trifluoroacetic acid, Ac=acetic acid, DCM=dichloromethane, DMSO=dimethylsulfoxide, Bu=butyl, Et=ethyl, Me=methyl, Bzl=benzyl. In the compounds listed, all proteinogenous amino acids are L-amino acids unless otherwise noted. Other abbreviations used: Me.sub.2Val=N,N-dimethylvaline, MeVal=N-methylvaline, Bn=benzyl, Me.sub.2Aib=[2-N,N-dimethylamino]-isobutyric acid.

General Procedures

The peptides of the invention are synthesized either by classical solution synthesis using standard Z- and Boc-methodology as described above or by standard methods of solid-phase synthesis using Boc and Fmoc protective group techniques.

In the case of solid phase synthesis, the N,N-dialkyl-penta- or hexapeptide acids are liberated from the solid support and further coupled with the corresponding C-terminal amines in solution. BOP-Cl and PyBrop were used as reagents for coupling of the amino acid following the N-methylamino acids. The reaction times were correspondingly increased. For reductive alkylation of the N-terminus, the peptide-resin was deprotected at the N terminus and then reacted with a 3-fold molar excess of aldehyde or ketone in DMF/1% acetic acid with addition of 3 equivalents of NaCNBH.sub.3. After the reaction was complete (negative Kaiser test) the resin was washed several times with water, isopropanol, DMF and dichloromethane.

In solution synthesis, the use of either Boc-protected amino acid NCAs (N-tert-butyloxycarbonyl-amino acid-N-carboxy-anhydrides), Z-protected amino acid NCAs (N-benzyloxycarbonyl-amino acid-N-carboxy-anhydrides), or the use of pivaloyl chloride as condensing agent respectively is most advantageous for coupling of the amino acid following the N-methylamino acids. Reductive alkylation of the N terminus can e.g. be achieved by reaction of the N-terminally deprotected peptides or amino acids with the corresponding aldehydes or ketones using NaCNBH.sub.3 or hydrogen-Pd/C.

Valyl-N-methylvalyl-prolyl-prolylbenzylamide hydrochloride for example was prepared according to methods disclosed in German Patent Application No. DE 19527575 A1.

Purification and Characterization of the Peptides

Peptide purification was carried out by gel chromatography (SEPHADEX G-10, G-15/10% HOAc, SEPHADEX LH.sub.20/MeOH), medium pressure chromatography (stationary phase: HD-SIL C-18, 20 45 micron, 100 Angstrom; mobile phase: gradient with A=0.1% TFA/MeOH, B=0.1% TFA/water), preparative HPLC (stationary phase: Waters Delta-Pak C-18, 15 micron, 100 Angstrom; mobile phase: gradient with A=0.1% TFA/MeOH, B=0.1% TFA/water), or by crystallization.

The purity of the resulting products was determined by analytical HPLC (stationary phase: 100 2.1 mm VYDAC C-18, 5 micron, 300 A; mobile phase: acetonitrile-water gradient, buffered with 0.1% TFA, 40.degree. C.; or 3.9 mm VYDAC C-18, 30.degree. C.). Characterization was by fast atom bombardment mass spectroscopy and NMR-spectroscopy.

Example 1

Synthesis of [N-Methyl-L-piperidine-2-carbonyl]-Val-MeVal-Pro-Pro-NHBn (Compound 1) and [N-Methyl-D-piperidine-2-carbonyl]-Val-MeVal-Pro-Pro-NHBn (Compound 2)

Preparation of N-methyl-piperidine-2-carboxylic acid

N-Methyl-piperidine-2-carboxylic acid ethyl ester (5.1 g) was dissolved in a mixture of 100 ml methanol and 10 ml water. NaOH (8 g) was added and the reaction mixture was stirred at room temperature overnight. The solution was then neutralized with hydrochloric acid, evaporated to dryness, and evaporated four times with toluene. The resulting powdery residue was used directly in the next step.

Preparation of [N-Methyl-piperidine-2-carbonyl]-Val-MeVal-Pro-Pro-NHBn

The residue prepared as described above (5.05 g) and H-Val-MeVal-Pro-Pro-NHBn.times.HCl (4.88 g) were dissolved in 50 ml dry DMF. After cooling the solution in an ice bath, 1.52 g DEPCN and 2.66 ml triethylamine were added. The reaction mixture was stirred at 0.degree. C. for 2 h and then at room temperature overnight. The DMF was removed by evaporation under reduced pressure. The residue was diluted with dichloromethane and the organic phase was washed with aqueous hydrochloric acid (pH 2) and water, dried over sodium sulfate and evaporated to dryness. The diastereomeric mixture was then separated by flash chromatography with a gradient using heptane/ethyl acetate and dichloromethane/methanol. Under the HPLC conditions described in the previous section (C-18 reverse phase) isomer 1 has a retention time of 14.9 minutes, and isomer 2 has a retention time of 15.8 minutes. Both isomers were characterized by fast atom bombardment mass spectrometry ([M+H]+=639).

Example 2

Preparation of Me.sub.2Aib-Val-MeVal-Pro-Pro-NHBn (Compound 3)

Preparation of 2-[N,N-dimethylamino]-isobutyric acid

2-Amino-isobutyric acid (10.3 g) was dissolved in 200 ml methanol. After addition of 25 ml aqueous formaldehyde and 1 g 10% Pd/C, the reaction mixture was hydrogenated overnight at room temperature. The catalyst was filtered, and the filtrate was evaporated to dryness. The residue was crystallized from isopropanol to give 4.8 g of the desired product.

Preparation of Me.sub.2Aib-Val-MeVal-Pro-Pro-NHBn.times.HCl

2-[N,N-Dimethylamino]-isobutyric acid (1.3 g, 10 mmol) and 5.5 g (10 mmol) H-Val-MeVal-Pro-Pro-NHBn.times.HCl were dissolved in 50 ml dry DMF. After cooling to 0.degree. C., 1.6 g DEPCN (10 mmol) and 2.9 ml triethylamine were added to the reaction mixture. The resulting mixture was stirred at 0.degree. C. for 2 h and at room temperature overnight. Ice water (50 mL) was then added, and the resulting mixture was extracted twice with diethyl ether. The ether extracts were washed with 1 N NaOH (1.times.) and aqueous NaCl (3.times.), then dried over sodium sulfate and evaporated to dryness under reduced pressure. The product was crystallized from 100 ml diethyl ether with HCl/ether, and recrystallized from acetone to give 1.2 g of the desired product, which was characterized by fast atom bombardment mass spectrometry ([M+H]+=627).

Example 3

Preparation of [N,N-dimethyl-2-ethyl-2-phenylglycyl]-Val-MeVal-Pro-Pro-NHBn.times.HCl (Compound 4)

Preparation of [N,N-dimethyl-2-ethyl-2-phenylglycyl]-Val-MeVal-Pro-Pro-NHBn.times.HCl

2.07 g (10 mmol) N,N-Dimethyl-2-ethyl-2-phenylglycine and 5.5 g (10 mmol) H-Val-MeVal-Pro-Pro-NHBn.times.HCl were dissolved in 100 ml dry DMF. After cooling to 0.degree. C., 1.6 g DEPCN (10 mmol) and 2.9 ml triethylamine were added. The reaction mixture was stirred at 0.degree. C. for 2 h and at room temperature overnight, then worked up as described above. The crude product was crystallized from diethyl ether with HCl/ether to give 4 g of the desired product, which was characterized by fast atom bombardment mass spectrometry ([M+H]+=703).

Example 4

Preparation of [N-Methyl-D-Pro]-Val-MeVal-Pro-Pro-NHBn (Compound 5)

Preparation of Z-D-Pro-Val-MeVal-Pro-Pro-NHBn

3.74 g Z-D-Pro-OH (15 mmol, BACHEM) and 8.25 g H-Val-MeVal-Pro-Pro-NHBn.times.HCl (15 mmol) were dissolved in 80 ml dry DMF. After cooling to 0.degree. C., 2.4 g DEPCN (2.25 ml, 15 mmol) and 4.2 ml triethylamine (30 mmol) were added. The reaction mixture was stirred at 0.degree. C. for several hours and room temperature overnight, then the DMF was evaporated under reduced pressure. The residue was diluted with ethyl acetate and thoroughly washed with dilute aqueous HCl (pH 2), water, dilute aqueous NaOH (pH 9 10), and water. The organic phase was dried over sodium sulfate and evaporated to dryness to yield 9.2 g of the desired protected pentapeptide.

Preparation of D-Pro-Val-MeVal-Pro-Pro-NHBn.times.HCl

8.2 g (11 mmol) Z-D-Pro-Val-MeVal-Pro-Pro-NHBn was dissolved in 70 ml methanol. After addition of 0.7 ml concentrated hydrochloric acid and 0.3 g 10% Palladium/charcoal to the solution, the resulting mixture was hydrogenated. Filtration and evaporation of the solvent gave a residue which was dissolved in water, adjusted to pH 2 and extracted twice with ethyl acetate. The aqueous phase was adjusted to pH 9 10 and extracted twice with dichloromethane. The organic extracts were evaporated and the residue was redissolved in diethylether and crystallized by addition of HCl/ether as the hydrochloride salt to give 6.5 g of the desired product.

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