Synthesis and antibacterial evaluation of some teicoplanin pseudoaglycon derivatives containing alkyl-and arylthiosubstituted maleimides

Article abstract of DOI:10.1038/ja.2015.33

Bis-Alkylthio maleimido derivatives have been prepared from teicoplanin pseudoaglycon by reaction of its primary amino group with N-ethoxycarbonyl bis-Alkylthiomaleimides. Some of the new derivatives displayed excellent antibacterial activity against resi

Full text of DOI:10.1038/ja.2015.33

The Journal of Antibiotics (2015), 1–7
2015 Japan Antibiotics Research Association All rights reserved 0021-8820/15
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&
ORIGINAL ARTICLE
Synthesis and antibacterial evaluation of some
teicoplanin pseudoaglycon derivatives containing
alkyl- and arylthiosubstituted maleimides
Magdolna Csávás1, Adrienn Miskovics1, Zsolt Szűcs1, Erzsébet Rőth1, Zsolt L Nagy1, Ilona Bereczki1,
Mihály Herczeg1, Gyula Batta2, Éva Nemes-Nikodém3, Eszter Ostorházi3, Ferenc Rozgonyi3, Anikó Borbás1 and
Pál Herczegh1 Dedicated to the memory of Professor Maria N Preobrazhenskaya✠
Bis-alkylthio maleimido derivatives have been prepared from teicoplanin pseudoaglycon by reaction of its primary amino group
with N-ethoxycarbonyl bis-alkylthiomaleimides. Some of the new derivatives displayed excellent antibacterial activity against
resistant bacteria.
The Journal of Antibiotics advance online publication, 1 April 2015; doi:10.1038/ja.2015.33
INTRODUCTION
Recently, Caddick, Baker and coworkers18–21 reported on applica-
tions of 3,4-dibromomaleimides for site-specific protein modification
and bioconjugation. The method is based on addition–elimination
reaction of thiols to the bromomaleimides leading to regeneration of
the double bond resulting in thiomaleimide products (Scheme 1). Last
year the group of Caddick and Baker published a simple method for
the synthesis of N-functionalised bromo- and thiomaleimides through
the corresponding N-ethoxycarbonyl maleimide derivatives.22 Apply-
ing these recent results of maleimide chemistry we describe here
derivatisation of teicoplanin pseudoaglycon with thiomaleimide sub-
stituents carrying two lipophilic alkyl or aryl sulfide side chains.
Glycopeptide antibiotics exert their antibacterial activity by inhibiting
two sequential enzymatic reactions—transglycosylation and transpep-
tidation—in the bacterial cell-wall biosynthesis. The antibiotics
recognize and tightly bind to the L-Lys-D-Ala-D-Ala termini of
peptidoglycan precursors at the external side of the developing
bacterial membrane. In this way transglycosylation and transpeptida-
tion are physically prevented, arresting cell-wall elongation and cross-
linking and leading to cell lysis.1 Due to the lack of cross-resistance to
other antibacterial drugs, the glycopeptide antibiotics have become
first-line drugs for the treatment of life-threatening multi-drug
resistant infections by Gram-positive bacteria.2
The emergence and spread of glycopeptide-resistant enterococci and
glycopeptide intermediate-resistant Staphylococcus aureus, as well as
teicoplanin-resistant Staphylococcus haemolyticus3 present a serious
global challenge and have led to renewed interest in the development
of novel, effective and safe antibacterials including new derivatives of
glycopeptide antibiotics.4–6
Inspired by the high activity of the semisynthetic lipoglycopeptide
antibiotics telavancin,7 dalbavancin8 and oritavancin9 against
vancomycin-resistant bacteria, we have started a program to produce
new antibiotics by introducing lipophilic subtituents to the primary
amino function of ristocetin aglycon and of teicoplanin pseudoagly-
con. Applying various approaches including squaric acid conjugation
method, azide-alkyne cycloaddition reaction or three-component
isoindole formation, we have prepared a large set of new derivatives
exhibiting high antibacterial10–13 and, in some cases, robust anti-
influenza virus activity.14–17
RESULTS AND DISCUSSION
Dibromomaleimide (1) that can be obtained by simple bromination of
maleimide23 has been allowed to react with a range of thiols including
the 6-thio-D-galactose derivative 2a, thiophenol 2b, phenylmetha-
nethiol 2c, dodecanethiol 2d, octanethiol 2e, propanethiol 2f and
t-butyl mercaptane 2h, representing a series of substituents of different
lipophilicity.
The obtained sulfides 3a–g have been then ethoxycarbonylated with
ethyl chloroformate in the presence of potassium carbonate to provide
5a–g, ready for a reaction with a primary amino group (Scheme 2).
Direct methoxycarbonylation22 of dibromomaleimide offers an alter-
native route for the synthesis of the targeted N-functionalized
dithiomaleimide as it is illustrated by the synthesis of 6g. We tested
this route with several thiols such as 2d–2g, however, the sulfide
formation showed low efficacy in all cases.
1Department of Pharmaceutical Chemistry, University of Debrecen, Debrecen, Hungary; 2Department of Organic Chemistry, University of Debrecen, Debrecen, Hungary and
3Department of Dermatology, Venerology and Dermatooncology, Microbiology Laboratory, Semmelweis University, Budapest, Hungary
✠Deceased on 25 December 2014
Correspondence: Professor A Borbás or Professor P Herczegh, Department of Pharmaceutical Chemistry, University of Debrecen, Egyetem tér 1, P.O.Box 70, Debrecen H-4010,
Hungary.
E-mail: borbas.aniko@pharm.unideb.hu or herczeghp@gmail.com
Received 19 December 2014; revised 18 February 2015; accepted 27 February 2015

Antibacterial evaluation of teicoplanin derivatives
M Csávás et al
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Next, teicoplanin pseudoaglycon 716 has been reacted with was a weak antibacterial and the bis-propylthio compound 8f
N-ethoxycarbonyl maleimides 5a–g and 6g in the presence of displayed very high activity. It can be supposed that a correlation
triethylamine (Table 1). In these reactions bis-alkyl- or arylthiomalei-
mide 8a–f were formed in moderate yields, together with the N-
alkoxycarbonyl derivatives of the teicoplanin pseudoaglycon (9 and
10). The formation of 9 and 10 can be explained by the steric
hindrance of the amino function of 7. In the case of 5g and 6g, the
undesired carbamate derivatives 9 and 10 were dominantly formed,
probably due to the presence of bulky t-butyl substituents of the
reagents.
Antibacterial activity of maleimido-teicoplanin-pseudoaglycons was
evaluated on a panel of Gram-positive bacteria (Table 2). The D-
galactose-containing 8a, the bis-phenylthio derivative 8b and the bis-
benzylthio derivative 8c displayed similar activities than teicoplanin
pseudoaglycon 7 with one exception: the maleimido compounds 8a–c
were active against Enterococcus faecalis 15 376 having vanA resistance
gene while teicoplanin and 7 were completely inactive against this
bacterium strain.
exists between lipophilicity of the maleimide substituents and anti-
bacterial activity, and the high lipophilicity erodes the activity. To test
this hypothesis, logP (logarithm of partition coefficient between n-
octanol and water) values were calculated for N-methyl maleimide
derivatives 11a–f and the calculated logP values corroborate our
postulation (Table 3).
In conclusion we have utilized, for the first time, bis-sulfide
derivatives of N-alkoxycarbonyl maleimide for versatile derivatisation
of teicoplanin pseudoaglycon. It turned out that lipophilicity of
substituents of the maleimide ring has strong influence on the
antibacterial activity of these derivatives. Further synthetic tuning of
these chemical structures hopefully will result in even more effective
antibacterials.
EXPERIMENTAL PROCEDURE
General information
The detected antibacterial activities of 8d, 8e and 8f were related to
the length of the alkyl chain substituents of their maleimide residues.
The bis-dodecyl derivative 8d was inactive, the bis-octyl derivative 8e
Maleimide and thiols 2b–2g were purchased from Sigma-Aldrich Chemical (St
Louis, MO, USA). 2,3-Dibromomaleimide 1, 1,2:3,4-di-O-isopropylidene-6-
deoxy-6-thio-α-D-galactopyranose 2a and teicoplanin pseudoaglycon 7 were
prepared according to literature procedures. TLC analysis was performed on
Kieselgel 60 F254 (Merck, Darmstadt, Germany) silica gel plates with visualiza-
tion by immersing in ammonium-molibdate solution followed by heating or
Pauly-reagent in the case of teicoplanin derivatives. Column chromatography
was performed on silica gel 60 (Merck 0.063–0.200 mm), flash column
chromatography was performed on silica gel 60 (Merck 0.040–0 0.063 mm).
Organic solutions were dried over MgSO4 and concentrated under vacuum.
R
N
R
N
R'SH
Et3N
O
O
O
O
1
The H (400 and 500 MHz) and 13C NMR (100.28, 125.76 MHz) spectra were
recorded with Bruker DRX-400 and Bruker Avance II 500 spectrometers.
Chemical shifts are referenced to Me4Si or DSS (2,2-Dimethyl-2-silapentane-5-
sulfonate sodium salt) (0.00 p.p.m. for 1H) and to solvent signals (CDCl3:
Br
Br
R'S
SR'
Scheme 1 Reaction of thiols with 3,4-dibromomaleimide.
EtO
O
H
N
EtO
O
H
RSH (2a-g)
Cl
O
O
N
Et3N
N
O
O
O
O
abs. CH2Cl2
rt, overnight
K2CO3
abs. acetone
rt, overnight
RS
SR
RS
SR
Br
Br
1
3a-g
5a-g
MeO
O
MeO
O
MeO
O
O
Cl
RSH (2g)
Et3N
K2CO3
abs. acetone
rt, overnight
N
N
O
O
O
abs. CH2Cl2
rt, overnight
S
S
Br
Br
6g
4
SH
RSH:
SH
SH
SH
2d
2e
O
2b
SH
O
O
SH
O
O
SH
2a
2g
2f
2c
Scheme 2 Synthesis of N-alkoxycarbonylated di-alkyl/arylthio-maleimide derivatives.
The Journal of Antibiotics

Antibacterial evaluation of teicoplanin derivatives
M Csávás et al
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Table 1 Synthesis and structure of teicoplanin pseudoaglycon-maleimide conjugates
Reagent
R
Products (yield %)
5a
5b
8a (15)
8b (21)
9a
9 (41)
Ph
5c
5d
5e
5f
Bn
8c (16)
8d (44)
8e (22)
8f (66)
8gb
9 (44)
9a
9a
n-dodecyl
n-octyl
n-propyl
t-butyl
t-butyl
9a
5g
6g
9 (59)
10 (48)
8gb
aFormation was observed (based on TLC), but it was not isolated.
bIdentified by MS method but it could not be isolated in pure form.
77.00 p.p.m., DMSO-d6: 39.51 p.p.m. for 13C). MALDI-TOF MS analyses for General method A for preparation maleimide bis-sulfides (3a–3g)
To a stirred solution of 2,3-dibromomaleimide23 (1.0 mmol) in CH2Cl2 (20 ml)
Et3N (2.0 mmol) and thiol (2.1 mmol) were added under argon atmosphere
and stirred for 3 h at room temperature. The reaction mixture was evaporated,
and the crude product was purified by flash chromatography to give the desired
compound.
the compounds 8b, 8c, 8e, 9 and 10 were carried out in positive reflectron
mode using a BIFLEX III mass spectrometer (Bruker, Bremen, Germany)
equipped with delayed-ion extraction. In the case of 8a, 8d and 8f, Matrix-
Assisted Laser Desorption/Ionization Time-of-flight (MALDI-TOF) MS spectra
were recorded by a Voyager-DE STR MALDI-TOF Biospectrometry Work-
station (Applied Biosystems, Budapest, Hungary). 2,5-Dihydroxybenzoic acid
was used as matrix and CF3COONa as cationising agent in DMF. Elemental
analysis (C, H, S) was performed on an Elementar Vario MicroCube
instrument. The antibacterial activity of 8a–f, 9 and 10 was tested against a
panel of Gram-positive bacteria using broth microdilution method as described
earlier.24
General method B for preparation N-ethoxycarbonyl maleimide
bis-sulfides (5a–5g)
To a stirred solution of maleimide bis-sulfide (1.0 mmol) in dry acetone
(20 ml) K2CO3 (1.2 mmol) and ethyl chloroformate (1.2 mmol) were added
The Journal of Antibiotics

Antibacterial evaluation of teicoplanin derivatives
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Table 2 Antibacterial activity of compounds 7–10
Teicoplanin
7
8a
8b
8c
8d
8e
8f
9
10
Bacillus subtilis ATCC 6633
0.5/16
0.5/2
2/16
2/32
4/256
4/256
4/256
1/256
4/256
1/256
4/256
2/256
4/32
2/16
2/16
1/8
4/32
4./32
4/32
128/256
64/256
64/256
8/256
32/256
8/64
1/256
1/256
64/256
16/128
4/64
8/64
8/64
Staphylococcus aureus MSSA ATCC 29213
Staphylococcus aureus MRSA ATCC 33591
Staphylococcus epidermidis biofilm ATCC 35984
Enterococcus faecalis ATCC 29212
Staphylococcus epidermidis mecA
0.5/2
1/16
2/16
1/256
8/64
2/32
2/32
0.5/2
0.5/64
0.5/4
0.5/32
0.5/64
1/8
0.5/256
1/256
4/32
4/64
2/64
4/32
1/64
2/16
1/256
2/64
8/256
8/256
2/16
8/256
4/32
8/256
8/64
16/32
256/256
4/256
1/32
8/256
0.5/256
1/256
Enterococcus faecalis 15376 vanA
256/256
2/32
128/256
64/256
32/256
8/128
16/256
8/128
8/256
8/128
Enterococcus faecalis ATCC 51299 vanB
1/256
Abbreviations: ATCC, American type culture collection; mecA, mecA gene expression in Staphylococcus; MRSA, methicillin resistant Staphylococcus aureus; MSSA, methicillin sensitive
Staphylococcus aureus; vanA +, vanA gene positive; vanB +, vanB gene positive.
Table 3 Calculated logP for N-methyl maleimide derivatives 11a–f
3.57–3.36 (4H, m, 2 × H-6a,b), 1.48, 1.44, 1.33, 1.32 (24H, 4 × s, 8 × CH3-ip);
13C NMR (100 MHz, CDCl3) δ 165.8 (2C, 2 × C = O), 137.2, 136.9 (2C, C = C),
109.5, 108.7 (4C, 4 × Cq-ip), 96.5 (2C, 2 × C-1), 71.5, 70.9, 70.4, 67.9 (8C,
skeleton carbons), 31.6 (2C, 2 × C-6), 25.9, 24.9, 24.4 (8C, 8 ×CH3); analysis
calculated for C28H39NO12S2 C 52.08, H 6.09, N 2.17, O 29.73, S 9.93. Found:
C 51.99, H 6.08, S 9.90.
Compound 3b. 2,3-Dibromomaleimide (255 mg, 1.0 mmol) was reacted
with thiophenol 2b (215 μl, 2.1 mmol) according to general method A.
The crude product was purified by silica gel chromatography in n-hexane:
acetone = 8:2, to give 3b (310 mg, 98%) as a yellow sirup. 1H NMR
(400 MHz, CDCl3) δ 7.83 (1H, s, NH), 7.29–7.17 (10H, m, arom); 13C
NMR (100 MHz, CDCl3) δ 166.5 (2C, 2 × C = O), 136.8 (2C, C = C), 131.9,
129.1, 128.6 (10C, arom), 128.9 (2C, Cq arom); analysis calculated for
C16H11NO2S2 C 61.32, H 3.54, N 4.47, O 10.21, S 20.46. Found: C 61.15,
H 3.53, S 20.39.
Compound
R
LogP
11a
0.54
Compound 3c. 2,3-Dibromomaleimide (510 mg, 2.0 mmol) was reacted with
benzyl mercaptan 2c (490 μl, 4.2 mmol) according to general method A. The
crude product was purified by silica gel chromatography in n-hexane:acetone =
8:2, to give 3c (460 mg, 67%) as a yellow sirup. 1H NMR (400 MHz, CDCl3) δ
7.78 (1H, s, NH), 7.29–7.26 (10H, m, arom), 4.42 (4H, s, 2 × SCH2); 13C NMR
(100 MHz, CDCl3) δ 175.3, 166.3 (2C, 2 × C = O), 136.5 (2C, C = C), 128.9,
128.8, 128.7, 127.7 (10C, arom), 36.2 (2C, 2 × SCH2); analysis calculated for
C18H15NO2S2 C 63.32, H 4.43, N 4.10, O 9.37, S 18.78. Found: C 63.19, H 4.45,
S 18.69.
11b
11c
11d
11e
11f
Ph
2.65
2.78
8.48
5.14
0.97
Bn
n-dodecyl
n-octyl
n-propyl
Compound 3d. 2,3-Dibromomaleimide (510 mg, 2.0 mmol) was reacted with
dodecyl mercaptan 2d (950 μl, 4.2 mmol) according to general method A. The
crude product was purified by silica gel chromatography in n-hexane:ethyl
under argon atmosphere and stirred for 3 h at room temperature. The
reaction mixture was diluted with CH2Cl2, filtered through a pad of Celite
and evaporated. The crude product was used for further step without
purification.
1
acetate = 9:1, to give 3d (670 mg, 67%) as a yellow sirup. H NMR (400 MHz,
CDCl3) δ 7.55 (1H, s, NH), 3.29–3.25 (4H, m, 2 × SCH2), 1.64–1.25 (40H, m,
20× CH2), 0.89–0.86 (6H, m, 2 × CH3); 13C NMR (100 MHz, CDCl3) δ 165.8
(2C, 2 × C = O), 136.4 (2C, C = C), 31.5, 31.4, 30.2, 29.3, 29.1, 28.9, 28.7, 28.1
(20C, 20 × CH2), 22.3 (2C, 2 × SCH2), 13.7 (2C, 2 × CH3). Analysis calculated
for C28H51NO2S2 C 67.55, H 10.33, N 2.81, O 6.43, S 12.88. Found: C 66.59, H
10.23, S 12.03.
General method C for the synthesis of teicoplanin pseudoaglycon
derivatives (8a–8f)
To a stirred solution of teicoplanin pseudoaglycon16 (0.1 mmol) in dry DMF
(5 ml) N-ethoxycarbonyl maleimide bis-sulfides (0.14 mmol) and Et3N (0.1
mmol) were added under argon atmosphere and stirred for overnight at room
temperature. The reaction mixture was evaporated, and the crude product was
purified by flash chromatography to give the desired compound.
Compound 3e. 2,3-Dibromomaleimide (255 mg, 1.0 mmol) was reacted with
octyl mercaptan 2e (364 μl, 2.1 mmol) according to general method A. The
crude product was purified by silica gel chromatography in n-hexane:acetone =
8:2, to give 3e (317 mg, 82%) as a yellow sirup. 1H NMR (400 MHz, CDCl3) δ
7.71 (1H, s, NH), 3.28 (4H, t, J = 7.5 Hz, 2 × SCH2), 1.69–1.60 (8H, m,
Compound 3a. 2,3-Dibromomaleimide (255 mg, 1.0 mmol) was reacted with
thiol 2a25 (580.4 mg, 2.1 mmol) according to general method A. The crude
product was purified by silica gel chromatography in n-hexane:acetone = 8:2, to
4 × CH2), 1.43–1.27 (20H, m, 10× CH2), 0.88 (6H, t, J = 6.8 Hz, 2 × CH3); 13
C
NMR (100 MHz, CDCl3) δ 166.3 (2C, 2 × C = O), 136.7 (2C, C = C), 31.8,
30.5, 29.0, 28.5 (12C, 12 × CH2), 22.6 (2C, 2 × SCH2), 14.0 (2C, 2 × CH3);
analysis calculated for C20H35NO2S2 C 62.29, H 9.15, N 3.63, O 8.30, S 16.63.
Found: C 61.03, H 9.08, S 16.08.
1
give 3a (550 mg, 85%) as a yellow sirup. H NMR (400 MHz, CDCl3) δ 7.58
(1H, s, NH), 5.51 (2H, d, J1,2 = 0.3 Hz, 2 × H-1), 4.62 (2H, d, J2,3 = 8.0 Hz,
2 × H-2), 4.32–4.30 (4H, m, 2 × H-3, 2 × H-4), 3.98–3.95 (2H, m, 2 × H-5),
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Antibacterial evaluation of teicoplanin derivatives
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Compound 3f. 2,3-Dibromomaleimide (510 mg, 2.0 mmol) was reacted
with propyl mercaptane 2f (380 μl, 4.2 mmol) according to general
method A. The crude product was purified by silica gel chromatography in
8:2, to give 8a (30 mg, 15%) as a yellow powder. MALDI-TOF MS: [M+Na]
+ = 2051.39 m/z. Calcd for C94H94Cl2N8O35S2Na 2051.45 m/z.
Compound 8b. Teicoplanin pseudoaglycon (140 mg 0.1 mmol) was reacted
with compound 5b (58 mg, 0.14 mmol) according to general method C. The
crude product was purified by silica gel chromatography in toluene:methanol=
8:2, to give 8a (35 mg, 21%) as a yellow powder. MALDI-TOF MS: [M+Na]
+ = 1719.41 m/z. Calcd for C82H66Cl2N8O25S2Na 1719.29 m/z.
n-hexane:ethyl acetate=9:1, to give 3f (430 mg, 87%) as
a yellow
sirup. 1H NMR (400 MHz, CDCl3) δ 7.77 (1H, s, NH), 3.28–3.25 (4H, m,
2 × SCH2), 1.73–1.66 (4H, m, 2 × CH2), 1.06–1.02 (6H, m, 2 × CH3);
13C NMR (100 MHz, CDCl3) δ 166.3 (2C, 2 × C = O), 137.2 (2C, C =C),
33.6 (2C, 2 × CH2), 23.8 (2C, 2 × SCH2), 13.1 (2C, 2 × CH3); analysis calculated
for C10H15NO2S2 C 48.95, H 6.16, N 5.71, O 13.04, S 26.14. Found: C 48.18, H
5.70, S 26.01.
Compound 8c. Teicoplanin pseudoaglycon (140 mg, 0.1 mmol) was reacted
with compound 5c (41 mg, 0.14 mmol) according to general method C. The
crude product was purified by silica gel chromatography in toluene:methanol=
7:3, to give 8c (27 mg, 16%) as a yellow powder. MALDI-TOF MS: [M+Na]
+ = 1747.47 m/z. Calcd for C84H70Cl2N8O25S2Na 1747.32 m/z.
Compound 3g. 2,3-Dibromomaleimide (510 mg, 2.0 mmol) was reacted with
t-butyl mercaptane 2g (473 μl, 4.2 mmol) according to general method A. The
crude product was purified by silica gel chromatography in n-hexane:ethyl
1
Compound 8d. Teicoplanin pseudoaglycon (140 mg, 0.1 mmol) was reacted
with compound 5d (74 mg, 0.14 mmol) according to general method C. The
crude product was purified by silica gel chromatography in toluene:methanol=
9:1, to give 8d (85 mg, 44%) as a yellow powder. MALDI-TOF MS: [M+Na]
+ = 1903.66 m/z. Calcd for C94H106Cl2N8O25S2Na 1903.60 m/z.
acetate = 9:1, to give 3g (432 mg, 80%) as a yellow sirup. H NMR (400 MHz,
CDCl3) δ 8.09 (1H, s, NH), 1.54 (18H, s, 6 × CH3); 13C NMR (100 MHz,
CDCl3) δ 166.9 (2C, 2 × C = O), 145.3 (2C, C = C), 51.9 (2C, 2 × SCq), 32.2
(6C, 6 × CH3); analysis calculated for C12H19NO2S2 C 52.71, H 7.00, N 5.12, O
11.70, S 23.46. Found: C 51.66, H 6.93, S 22.89.
Compound 8e. Teicoplanin pseudoaglycon (140 mg, 0.1 mmol) was reacted
with compound 5e (69 mg, 0.14 mmol) according to general method C. The
crude product was purified by silica gel chromatography in toluene:methanol=
8:2, to give 8d (38 mg, 22%) as a yellow powder. MALDI-TOF MS: [M+Na]
+ = 1791.64 m/z. Calcd for C86H90Cl2N8O25S2Na 1791.47 m/z.
Compound 6g. To a stirred solution of 2,3-dibromomaleimide (0.255 g, 1.0
mmol) in tetrahydrofuran (4 ml) N-methylmorpholine (76 μl, 1.1 mmol) and
methyl chloroformate (85 μl, 1.1 mmol) were added at 0 °C. When TLC (n-
hexane:acetone = 8:2) showed complete conversion of the starting material
(3 h), the reaction mixture was diluted with CH2Cl2, filtered through a pad of
Celite and evaporated. The obtained crude 4 (0.308 g) was reacted, without
purification, with t-butyl mercaptan 2g (237 μl, 2.1 mmol) according to general
method A to give compound 6g (0.150 g). The crude product was used for
further step without purification.
Compound 8f. Teicoplanin pseudoaglycon (140 mg, 0.1 mmol) was reacted
with compound 5f (40 mg, 0.14 mmol) according to general method C. The
crude product was purified by silica gel chromatography in toluene:methanol=
9:1, to give 8d (110 mg, 66%) as a yellow powder. MALDI-TOF MS: [M+Na]
+ = 1651.02 m/z. Calcd for C76H70Cl2N8O25S2Na 1651.32 m/z.
Compound 8a. Teicoplanin pseudoaglycon (140 mg, 0.1 mmol) was reacted
with compound 5a (100 mg, 0.14 mmol) according to general method C. The
Compound 9. Teicoplanin pseudoaglycon (140 mg, 0.1 mmol) was reacted
crude product was purified by silica gel chromatography in toluene:methanol= with compound 5g (49 mg, 0.14 mmol) according to general method C. The
Table 4 1H and 13C NMR data for compounds 8a, 8b, 8c and 8d (chemical shifts in ppm)
Assignment
8a 13C
8a 1H
8b 13C
8b 1H
8c 13C
8c 1H
8d 13C
8d 1H
x1
64.8
55.6
7.05
4.98
5.32
5.59
5.40
7.68
6.32
5.57
5.07
7.09
4.40
64.8
55.9
7.07
4.98
5.29
5.58
5.45
7.67
6.28
5.53
5.06
7.09
4.39
64.9
55.9
7.06
4.99
5.33
5.59
5.42
7.65
6.32
5.55
5.07
7.09
4.36
64.6
55.5
7.05
4.98
5.36
5.64
5.42
7.69
6.39
5.55
5.06
7.11
4.39
x2
x3
59.2
59.1
59.2
59.1
x4
54.8
54.8
54.9
54.8
z6
76.8
76.2
76.7
76.3
2f
131.5
109.7
107.9
104.6
136.3
98.4
131.6
109.7
108.2
104.8
136.6
98.8
131.5
110.2
108.3
104.9
136.6
99.0
131.8
110.0
108.2
104.9
136.5
99.0
3b
4b
4f
5b
GlcNAc 1
Maleimide 2
Maleimide 3
Maleimide 4
Maleimide 5
SCH2
165.3
135.3
135.3
165.3
165.4
135.3
135.3
165.4
165.4
136.8
136.8
165.4
35.5
165.5
134.2
134.2
165.5
31.5
4.42–4.37
3.33–3.21
α-Galp 1
α-Galp 2
α-Galp 3
α-Galp 4
α-Galp 5
α-Galp 6
iP-Cq
95.7
69.7
5.41
4.30
70.2
4.60
70.9
4.22
67.2
3.82
31.2
3.37–3.27
108.8; 108.6
31.5–24.2
iP-CH3
Ph
1.40–1.23
131.0–128.18
7.29–7.15
The Journal of Antibiotics

Antibacterial evaluation of teicoplanin derivatives
M CsáAvábsstreatcatsl
67
Table 5 1H and 13C NMR data for compounds 8e, 8f, 9 and 10 (chemical shifts in p.p.m.)
Assignment
8e 13C
8e 1H
8f 13C
8f 1H
9
13C
9
1H
10 13C
10 1H
x1
64.8
56.0
7.05
4.99
5.42
5.57
5.42
7.64
6.32
5.57
5.08
7.09
4.38
64.8
55.7
7.05
4.99
5.42
5.58
5.42
7.64
6.32
5.54
5.08
7.09
4.38
64.8
55.7
7.05
4.98
5.34
5.62
5.42
7.63
6.32
5.53
5.09
7.2
64.8
56.0
7.06
4.98
5.42
5.59
5.42
7.66
6.33
5.51
5.08
7.09
4.38
x2
x3
59.4
59.2
58.9
59.3
x4
54.9
54.8
54.8
54.8
z6
76.0
76.2
76.8
76.3
2f
131.3
110.0
108.3
104.8
136.6
99.3
131.0
110.0
108.1
104.7
136.3
99.4
131.8
110.0
107.6
104.8
136.2
99.8
131.5
109.9
108.0
104.8
136.1
98.6
3b
4b
4f
5b
GlcNAc 1
Maleimide 2
Maleimide 3
Maleimide 4
Maleimide 5
SCH2
CH2
4.36
165.5
138.5
138.5
165.5
31.0
165.4
135.4
135.4
165.4
32.9
3.25–3.17
1.56–1.14
0.86–0.82
3.28–3.15
1.60–1.55
0.95–0.93
29.9–21.9
13.8
23.4
CH3
12.8
NH 1
CO 2
7.96
169.9
169.5
51.5
7.86
3.56
OCH3
OCH2
CH3
60.1
14.8
4.05–4.01
1.18–1.15
Figure 1 Structure and numbering for compounds 8a–f, 9 and 10. A full color version of this figure is available at The Journal of Antibiotics journal online.
crude product was purified by silica gel chromatography in toluene:methanol= Compound 10. Teicoplanin pseudoaglycon (210 mg, 0.15 mmol) was
reacted with compound 6g (70 mg, 0.21 mmol) according to general
9:1, to give 9 (87 mg, 59%) as a yellow powder. MALDI-TOF MS: [M+Na]
+ = 1495.34 m/z. Calcd for C69H62Cl2N8O25Na 1495.31 m/z.
method C. The crude product was purified by silica gel chromatography
The Journal of Antibiotics

Antibacterial evaluation of teicoplanin derivatives
M Csávás et al
7
in toluene:methanol = 8:2, to give 10 (120 mg, 48%) as a yellow powder.
MALDI-TOF MS: [M+Na]+ = 1481.51 m/z. Calcd for C68H60Cl2N8O25Na
1481.29 m/z.
8
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NMR analysis
The 1H and 13C NMR data of the teicoplanin derivatives 8a–f, 9 and 10 are
collected in Tables 4 and 5. The spectra were recorded at 500.13/125.76 MHz
frequencies, respectively, at 300 K, using DMSO-d6, as solvent. Numbering
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mixing time) experiments.
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This research was supported by the European Union and the State of Hungary,
co-financed by the European Social Fund in the framework of TÁMOP 4.2.4.A/
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by the Hungarian Research Fund (OTKA K 109208 and ANN 110821) and by
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The Journal of Antibiotics