Chemistry: natural resins or derivatives; peptides or proteins; – Peptides of 3 to 100 amino acid residues – Cyclic peptides
Reexamination Certificate
2000-09-26
2003-12-30
Low, Christopher S. F. (Department: 1653)
Chemistry: natural resins or derivatives; peptides or proteins;
Peptides of 3 to 100 amino acid residues
Cyclic peptides
C514S008100, C514S011400, C530S322000
Reexamination Certificate
active
06670446
ABSTRACT:
The present invention is directed to glycopeptides and is directed in particular to modifications of A82846B and its N
DISACC
variations. In the claimed compounds, the original N
1
amino acid, N-methyl-D-leucine, has been removed and replaced with an acyl group or with an acyl group derived from an alternate &agr;-amino acid.
The present invention is directed to compounds of the formula
where in R
1
represents
alkanoyl of C
2
-C
10
which is unsubstituted, or which is substituted by a phenyl, or which is substituted on other than the &agr;-carbon atom by an amino or protected amino group;
benzoyl or substituted benzoyl bearing one or two substituents each of which is independently halo, loweralkyl of C
1
-C
4
, loweralkoxy of C
1
-C
4
or phenyl;
an acyl derived from an &agr;-amino acid or an acyl derived from a protected &agr;-amino acid, said &agr;-amino acid being selected from the group consisting of:
alanine,
arginine,
asparagine,
aspartic acid,
cysteine,
glutamic acid,
glutamine,
glycine,
histidine,
isoleucine,
leucine,
lysine,
methionine,
3-phenylalanine,
3-(p-chlorophenyl) alanine,
proline,
serine,
threonine,
tryptophan and valine,
in either D- or L-form; or
an acyl derived from an &agr;-amino acid as defined above which bears on the amine a substituent which is alkyl of C
1
-C
10
, benzyl, phenylbenzyl, or p-chlorobenzyl, with the proviso that the acyl derived from N-methyl-D-leucine is excluded;
R
2
represents hydrogen, or epivancosaminyl of the formula
wherein R
2a
represents hydrogen or —CH
2
—R
3
; and R
3
represents hydrogen, alkyl of C
1
-C
11
, alkyl of C
1
-C
11
-R
4
, or R
4
-(linker
(0 or 1)
-R
4
)
o or
1,
wherein each R
4
is independently phenyl or phenyl substituted by one or two substituents, each of which is independently halo, loweralkyl of C
1
-C
8
, loweralkoxy of C
1
-C
8
, loweralkylthio of C
1
-C
4
, or trifluoromethyl, and “linker” is —O—, —CH
2
—, or —O—(CH
2
)
n
— wherein n is 1-3; and the pharmaceutically acceptable salts thereof.
When R
1
represents alkanoyl of C
2
-C
10
, it can be a straight-chain alkanoyl, or it can be an alkanoyl which is branched to any degree. Likewise, when R
3
represents alkyl of C
1
-C
11
, it can be straight-chain or branched.
The compounds of the present invention are prepared from the corresponding “A82846B hexapeptides” of the formula:
wherein R
2
is as defined above. These “A82846B hexapeptides” are so called because the normal N
1
amino acid N-methyl-D-leucine, has been removed, reducing the number of amino acids in the parent glycopeptide from seven to six.
The compounds of the present invention are prepared by reacting an A82846B hexapeptide with an activated ester of an alkanoic acid of the desired acyl group R
1
. By “activated ester” is meant an ester which renders the carboxyl function more reactive to coupling with the amine of the A82846B hexapeptide. The reaction of the A82846B hexapeptide and activated ester is carried out in an organic solvent, suitably a polar solvent such as dimethylformamide, dimethyl sulfoxide, or a mixture of dimethylformamide and dimethyl sulfoxide. The reaction proceeds under temperatures of a wide range, such as 250 to 100° C., but is preferably carried out at temperatures of about 25 to 35° C. Some of the desired product is produced shortly upon contacting the reactants, but higher yields are obtained with reaction times of from about 1 to about 24 hours, oftentimes from about 1 to about 5 hours. Isolation and purification are carried out under conventional procedures.
The starting A82846B hexapeptides are themselves synthesized from the parent glycopeptides:
wherein R
2a
is as defined above. This synthesis is by the “Edman degradation”, a two-step process for the cleavage of the N-terminal residue of a peptide or protein. The above parent glycopeptide is first reacted with an isothiocyanate of the formula SCN-R
5
, to obtain an intermediate N
LEU
-(thiocarbamoyl)-A82846B compound of the formula
In the foregoing formula, R
5
represents alkyl of C
1
-C
10
, phenyl, naphthyl, or phenyl substituted by one or two substituents, each of which is independently halo, loweralkyl of C
1
-C
4
, loweralkoxy of C
1
-C
4
, benzyloxy, nitro, or
wherein each R
6
is independently loweralkyl of C
1
-C
4
.
This reaction is conveniently carried out in water with pyridine, at a temperature of 25°-30° C., employing a slight excess of the isothiocyanate reactant. The N
LEU
-(thiocarbamoyl)A82846B intermediate can be separated in conventional manner or can be employed after removal of reaction solvent in the second step of the Edman degradation.
In the second step, the N
LEU-
(thiocarbamoyl)A82846B is reacted with an organic acid, preferably trifluoroacetic acid, in a non-polar solvent such a dichloromethane. The reaction proceeds at temperatures of from 0° C. to 35° C. but is preferably carried out at temperatures of from 0° C. to 25° C. The reaction is generally complete in several hours. The resulting hexapeptide product is separated and purified if desired in conventional procedures.
The second step of the Edman degradation can in some instances result in loss of the disaccharide epivancosamine. Longer reaction times can be used to obtain the desepivancosaminyl compound (R
2
=hydrogen).
Other variations at the disaccharide position of the molecule can be obtained in conventional procedures. As described above, the Edman degradation and subsequent acylation can be carried out with the naturally-occurring disaccharide (R
2
=epivancosaminyl with R
2a
=H) or with a disaccharide derivative (R
2
=epivancosaminyl with R
2a
=CH
2
—R
3
). This approach to synthesis of the present compounds is illustrated by the preparations below of Examples 12 and 26. However, it is also possible to prepare those claimed compounds with a disaccharide derivative (R
2
=epivancosaminyl with R
2a
=—CH
2
—R
3
) by first conducting the Edman degradation and subsequent acylation on A82846B, with its naturally occurring R
2
=epivancosaminyl, and thereafter introducing the desired epivancosaminyl substituent —CH
2
—R
3
. This is illustrated by Examples 34 and 35.
Whether the —CH
2
—R
3
substituent is introduced prior to Edman degradation and acylation, or after, the same conventional process is used. In this process, the substrate compound is reductively alkylated with the aldehyde suitable to introduce the desired —CH
2
—R
3
group. This process is taught in various references, see U.S. Pat. No. 5,591,714, and EPO 667,353.
The compounds of the present invention readily form salts, which can be prepared in conventional manner.
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patent: 4639433 (1987-01-01), Hunt et al.
patent: 4643987 (1987-02-01), Nagarajan et al.
patent: 4698327 (1987-10-01), Nagarajan et al.
patent: 5312738 (1994-05-01), Hamill et al.
patent: 5534420 (1996-07-01), Debono et al.
patent: 5591714 (1997-01-01), Nagarajan et al.
patent: 435503 (1991-07-01), None
patent: 435503 (1991-07-01), None
patent: 667353 (1995-08-01), None
Allen, N. et al., “Hexapeptide Derivatives of Glycopeptide Antibiotics: Tools for Mechanism of Action Studies,”Antimicrobial Agents and Chemotherapy, vol. 46, No. 8, pp. 2344-2348 (Aug. 2002).
Harris, C. et al., “The Role of the Chlorine Substituents in the Antibiotic Vancomycin: Preparation and Characterization of Mono- and Didechlorovancomycin,”J. Am. Chem. Soc., vol. 107, pp. 6652-6658 (1985).
Kannan, R. et al., “Function of the Amino Sugar and N-Terminal Amino Acid of the Antibiotic Vancomycin in Its Complexation with Cell Wall Peptides,”J. Am. Chem. Soc., vol. 110, pp. 2946-2953 (1988).
Mackay, J. et al., “Glycopeptide Antibiotic Activity and the Possible Role of Dimerization: A Model for Biological Signaling,”J. Am. Chem. Soc., vol. 116, pp. 4581-4590 (1994).
Walsh, C.T. et al., “Bacterial Resistance to Vancomycin: Five Genes and One Missing Hydrogen Bond Tell the Story,”Chemistry&Biology, vol. 3, No. 1, pp. 21-28 (Jan. 1996).
Nagarajan, J. Antibiotics, 1993, 46, 1181-1195.
Nagarajan, Schabel, J. Chem. Soc., Chem. Commun. 1988, 1306-130
Thompson Richard Craig
Wilkie Stephen Charles
Eli Lilly and Company
Low Christopher S. F.
Lukton David
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