Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives

Article abstract of DOI:10.1016/j.ejmech.2016.10.065

Novel series of novel 3-O-arylalkylcarbamoyl descladinosylazithromycin derivatives with the 2′-O-acetyl and 11,12-cyclic carbonate groups, the 11,12-cyclic carbonate group and the 11-O-arylalkylcarbamoyl side chain, and 2′-O-arylalkylcarbamoyl descladinos

Full text of DOI:10.1016/j.ejmech.2016.10.065

European Journal of Medicinal Chemistry xxx (2016) 1e11
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis and antibacterial activity of novel
3-O-descladinosylazithromycin derivatives
,
*
Mi Yan a, Ruixin Ma b, Li Jia a, Henrietta Venter c, Shutao Ma a
a Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University,
44 West Culture Road, Jinan 250012, China
b The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao 266003, China
c School of Pharmacy & Medical Sciences, Sansom Institute for Health Research, University of South Australia, GPO Box 2471, Adelaide 5001, Australia
a r t i c l e i n f o
a b s t r a c t
Novel series of novel 3-O-arylalkylcarbamoyl descladinosylazithromycin derivatives with the 20-O-acetyl
and 11,12-cyclic carbonate groups, the 11,12-cyclic carbonate group and the 11-O-arylalkylcarbamoyl side
chain, and 20-O-arylalkylcarbamoyl descladinosylazithromycin with the 11,12-cyclic carbonate group
were designed, synthesized and evaluated for their antibacterial activity using broth microdilution
method. The results showed that the majority of the target compounds showed moderate to favorable
activity against six kinds of susceptible strains and almost all of them displayed significantly improved
activity compared with references against three erythromycin-resistant strains of S. pneumoniae B1
expressing the ermB gene, S. pneumoniae AB11 expressing the ermB and mefA genes, and S. pyogenes R1.
In particular, compound 6h exhibited the most potent activity against susceptible B. subtilis ATCC9372
Article history:
Received 7 September 2016
Received in revised form
14 October 2016
Accepted 31 October 2016
Available online xxx
Keywords:
Antibacterial activity
3-O-Descladinosylazithromycin
Erythromycin-resistant bacteria
Synthesis
(0.5
B1 (1
azithromycin, respectively. Additionally, compounds 6f (0.5
active against S. pneumoniae A22072, which were 8- and 16-fold better activity than azithromycin (4
mL). As for erythromycin-resistant S. pyogenes R1, compound 5a presented the most excellent activity
(8 g/mL), showing 32- and 32-fold higher activity than azithromycin (256 g/mL) and clarithromycin
(256 g/mL).
m
g/mL), penicillin-resistant S. epidermidis (0.125
g/mL) and S. pneumoniae AB11 (1 g/mL), which were 2-, 2-, 256-, 256-fold better activity than
g/mL) and 6g (0.25 g/mL) were the most
g/
mg/mL), and erythromycin-resistant S. pneumoniae
m
m
m
m
m
m
m
m
© 2016 Elsevier Masson SAS. All rights reserved.
1. Introduction
mechanisms of resistance are target modification mediated by ermB
gene and drug efflux mediated by mefA gene, respectively. A methyl
transferase encoded by the erm gene can dimethylate the nucleotide
A2058 of 23S rRNA in bacterial ribosome, thereby leading to no
interaction between the macrolide antibiotics and the ribosome
[5e7]. The ermB-positivebacterial strains showedcross resistance to
macrolides, lincosamides and streptogramin B (MLSB) antibiotics. As
for the second mechanism, an efflux transporter encoded by the mef
gene can pump the macrolides out of the bacterial cell [8].
The emergence and prevalence of resistant pathogens makes it
an urgent need to investigate new antibacterial agents. Conse-
quently, the third-generation macrolides such as ketolides are
discovered [4,9]. The C-6 side chain or the C-11,12 cyclic carbamate
side chain of ketolides (e.g., telithromycin and cethromycin) (Fig. 1)
can interact with the nucleotide A752 in domain II of 23S rRNA in
addition to binding to the nucleotide A2058 in domain V of the 23S
rRNA. These interactions result in tighter affinity for bacterial ri-
bosomes. Therefore, the ketolides can exhibit strong activity
First generation macrolide antibiotics (e.g. erythromycin A)
(Fig. 1) have been introduced for over 60 years and been used in
treating upper and lower respiratory tract infections in clinic [1,2].
However, erythromycin A (EMA) can degrade under the acidic
conditions of stomach, and the resultant 6,9-hemiketal degradation
products might result in gastrointestinal side effects and poor
bioavailability [3]. To approach the acid instability of EMA, scien-
tists developed the second generation macrolides such as azi-
thromycin and clarithromycin (Fig. 1) with improved antibacterial
activity and pharmacokinetic properties compared with EMA [4].
However, the therapeutic utility of the macrolide antibiotics has
been limited by the emergence of bacterial resistance. The two main
* Corresponding author.
E-mail address: mashutao@sdu.edu.cn (S. Ma).
http://dx.doi.org/10.1016/j.ejmech.2016.10.065
0223-5234/© 2016 Elsevier Masson SAS. All rights reserved.
Please cite this article in press as: M. Yan, et al., Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives,
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2
M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
Fig. 1. Structures of erythromycin, azithromycin, clarithromycin, telithromycin, cethromycin, TEA0929 and TEA0777.
against the ermB-positive bacterial strains whose ribosomes are
methylated [10e12].
stacking or electrostatic interactions [17e19]. In addition, 20-O-
arylalkylcarbamoyl derivatives were also designed, synthesized
and evaluated for their antibacterial activity mainly to explore their
structureeactivity relationships that have not been reported so far
[20,21].
An X-ray cocrystal structure research has revealed that macro-
lide antibiotics bind at the entrance to the peptide exit tunnel in the
23S rRNA of the 50S ribosomal subunit, and its cladinose fits tightly
over the base planes formed by G2505, C2610 and C2611 in domain
V [13]. For that reason, a new class of macrolide antibiotics called
acylides have been discovered. For instance, TEA0929 and TEA0777
(Fig. 1) hopefully shows excellent activity against efflux-resistant
S. pneumoniae in addition to MLSB-resistant S. aureus [14,15]. The
discovery of the acylides represented one of the most important
breakthroughs in the process of developing novel macrolides to
overcome the mef-mediated bacterial resistance effectively [16].
Based on the considerations detailed above, we designed and
synthesized four series of novel 3-O-arylalkylcarbamoyl descladi-
nosylazithromycin derivatives with the 20-O-acetyl and 11,12-cyclic
carbonate groups (4a-h), the 11,12-cyclic carbonate group (5a-m)
and the 11-O-arylalkylcarbamoyl side chain (6a-i), and 20-O-ary-
lalkylcarbamoyl descladinosylazithromycin with the 11,12-cyclic
carbonate group (8a-h) to prevent the erm- or mef-mediated bac-
teria and broaden their antibacterial spectra. The 3-O-ary-
2. Chemistry
2.1. Synthesis of 11,12-cyclic carbonate descladinosylazithromycin
20-O-acetyl-3-O-arylalkylcarbamoyl derivatives
The synthetic method for 11,12-cyclic carbonate descladinosy-
lazithromycin 20-O-acetyl-3-O-arylalkylcarbamoyl derivatives is
shown in Scheme 1. Selective cleavage of the 3-O-sugar moiety
from AZM with 1M aqueous hydrochloric acid (HCl) and subse-
quent protection of the 2'-hydroxyl group with acetic anhydride
(Ac2O) in the presence of triethylamine (Et3N) gave 2'-acetate
product (2) [22,23]. 11,12-Carbonate 20-O-acetyl-3-O-acylimidazo-
lide 3 was prepared in toluene at 55 ꢀC by treatment of 2 with CDI in
the presence of triethylamine. 20-O-acetyl-3-O-arylalkylcarbamoyl
derivatives (4a-h) were obtained in 62e71% yields by condensation
of 3 with the corresponding arylamines in the presence of pyridine
hydrochloride [24,25].
lalkylcarbamoyl
side
chain
attached
to
the
descladinosylazithromycin skeleton was not only to inhibit the
hydrolysis of the 3-O-acyl group on the acylides in the body, but
also was liable to interact with the binding pocket composed of
G2505, C2610 and C2611 in domain V. On the other hand, the C-
11,12 cyclic carbonate group or 11-O-arylalkylcarbamoyl side chain
introduced to the descladinosylazithromycin skeleton was excep-
2.2. Synthesis of 11,12-cyclic carbonate descladinosylazithromycin
3-O-arylalkylcarbamoyl derivatives
The synthetic method for 11,12-cyclic carbonate descladinosy-
lazithromycin 3-O-arylalkylcarbamoyl derivatives is shown in
ted to bind with A752 in domain II through hydrogen bonding, p-
Please cite this article in press as: M. Yan, et al., Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives,
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M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
3
2.3. Synthesis of 11,3-di-O-arylalkylcarbamoyl
descladinosylazithromycin derivatives
11, 3-Di-O-arylalkylcarbamoyl descladinosylazithromycin deriva-
tivesc were synthesized from compound 4 (Scheme 3). Compound 4
with an aromatic side chain at the 3-position was deprotected and
then readily converted to novel 11,3-di-O-arylalkylcarbamoyl
descladinosylazithromycin derivatives (6a-i) by reacting with the
corresponding amines in the presence of pyridine hydrochloride.
2.4. Synthesis of 11,12-cyclic carbonate descladinosylazithromycin
20-O-arylalkylcarbamoyl derivatives
Treatment of descladinosylazithromycin 1 with CDI in the
presence of trimethylamine in toluene provided 11,12-carbonate 20-
O-acylimidazolide 7. And then the reaction of 7 with the corre-
sponding amines in the presence of pyridine hydrochloride pro-
duced novel 11,12-cyclic carbonate descladinosylazithromycin 20-
Scheme 1. Synthetic route for 11,12-cyclic carbonate descladinosylazithromycin 20-O-
acetyl-3-O-arylalkylcarbamoyl derivatives 4a-h. Regents and Conditions: (a) 1M HCl,
CH3OH; (b) (CH3CO)2O, CH2Cl2, Et3N, rt, 24 h; (c) CDI, Et3N, toluene, 55 ꢀC, 72 h; (d)
R1NH2, pyridine hydrochloride, rt, 6e8 days.
Scheme 2. 11,12-Carbonate 20-O-acetyl-3-O-acylimidazolide 3 was
prepared in toluene at 55 ꢀC by treatment of 2 with CDI in the
presence of triethylamine. 3-O-Arylalkylcarbamoyl descladinosy-
lazithromycin derivatives (5a-m) were obtained in 62e71% yields
by condensation of 3 with the corresponding arylamines in the
presence of pyridine hydrochloride, followed by selective removal
of the 20-O-acetyl group by heating with methanol [26].
Scheme 3. Synthetic route for 11,3-di-O-arylalkylcarbamoyl descladinosylazi-
thromycin derivatives 6a-i. Regents and Conditions: (a) CH3OH, 55 ꢀC, 12 h; (b) R2NH2,
pyridine hydrochloride, rt, 72 h.
Scheme 2. Synthetic route for 11,12-cyclic carbonate descladinosylazithromycin 3-O-
arylalkylcarbamoyl derivatives 5a-m. Regents and Conditions: (a) R1NH2, pyridine
hydrochloride, rt, 6e8 days; (b) CH3OH, 55 ꢀC, 12 h.
Scheme 4. Synthetic route for 11,12-cyclic carbonate descladinosylazithromycin 20-O-
arylalkylcarbamoyl derivatives 8a-h. Regents and Conditions: (a) CDI, Et3N, toluene,
55 ꢀC, 72 h; (b) R1NH2, pyridine hydrochloride, rt, 6e8 days.
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4
M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
O-arylalkylcarbamoyl derivatives (8a-h) (Scheme 4).
aeruginosa ATCC27853 (penicillin-susceptible strain), S. aureus
ATCC29213 (methicillin-resistant strain), S. pneumoniae B1 (eryth-
romycin-resistant strain expressing the erm gene), S. pneumoniae
A22072 (erythromycin-resistant strain expressing the mef gene),
S. pneumoniae AB11 (erythromycin-resistant strain expressing the
erm and mef genes), S. pyogenes R1 (erythromycin-resistant strain
isolated clinically). Their MIC results are shown in Table 1.
3. Antibacterial evaluation
All the compounds synthesized above were evaluated for their
in vitro antibacterial activity by the broth microdilution method
recommended by NCCL [10]. Minimal inhibitory concentration
(MIC) values for all compounds were determined in comparison
with AZM and CLA on a panel of susceptible and resistant Gram-
positive strains that are Staphylococcus aureus ATCC25923 (eryth-
romycin-susceptible strain), Streptococcus pyogenes (erythromycin-
susceptible strain isolated clinically), Escherichia. coli ATCC25922
(penicillin-susceptible strain), Staphylococcus Epidermidis (peni-
cillin-resistant strain isolated clinically, not characterized), Bacillus
subtilis ATCC9372 (penicillin-susceptible strain), Pseudomonas
4. Results and discussion
11,12-Cyclic carbonate azithromycin 20-O-acetyl-3-O-ary-
lalkylcarbamoyl derivatives 4a-h showed slightly improved anti-
bacterial activity against S. pneumoniae expressing the ermB gene,
S. pneumoniae expressing the ermB and mefA genes, and
erythromycin-resistant S. pyogenes R1. Among them, the most
Table 1
3-O-Descladinosylazithromycin derivatives with their in vitro antibacterial activity against susceptible and resistant strains (mg/mL).
Compound S. aureus
ATCC 25923a 25922b
E. coli ATCC S. pyogenesc P. aeruginosa
B. subtilis
S. epidermidisf S. aureus
ATCC 29213g B1h
S. pneumoniae S. pneumoniae S. pneumonae S. pyogenes
ATCC 27853d
ATCC 9372e
A22072i
AB11j
R1k
3
128
32
16
32
32
64
32
16
ND
2
2
4
8
16
ND
8
32
32
64
64
8
0.25
1
4
2
8
4
4
ND
0.25
1
0.5
0.5
2
ND
0.125
0.25
0.25
2
128
64
64
128
64
128
128
128
ND
128
64
128
32
8
32
16
64
32
8
128
16
128
64
32
64
32
16
128
4
128
128
64
64
64
64
64
32
ND
128
64
32
64
64
ND
64
64
64
128
128
128
64
128
128
64
128
128
64
256
128
256
128
128
128
64
64
ND
16
64
32
64
64
ND
64
32
32
64
32
32
64
64
128
64
64
128
8
32
16
4
8
256
64
16
32
32
64
128
16
ND
16
16
1
16
16
ND
4
4
8
56
4a
4b
4c
4d
4e
4f
4g
4h
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
6a
6b
6b
6d
6e
6f
6g
6h
6i
128
256
128
128
128
128
32
ND
8
32
32
64
64
ND
128
32
64
128
64
64
64
64
64
64
32
128
32
128
32
ND
256
128
64
64
128
64
64
128
64
256
256
8
64
16
32
32
64
ND
16
8
128
128
128
ND
128
64
64
64
64
ND
128
128
128
128
128
128
64
128
64
64
64
128
64
ND
4
8
4
4
4
64
64
64
2
4
32
16
ND
8
16
16
128
64
32
4
32
8
4
8
16
4
16
16
ND
1
1
2
16
8
4
32
ND
64
0.5
64
64
0.5
0.25
8
16
32
16
4
32
0.25
0.25
0.125
ND
32
32
16
32
64
32
64
64
64
0.25
0.25
ND
128
128
128
128
128
128
64
128
64
64
64
128
64
8
32
32
16
16
4
32
32
16
8
32
8
4
4
64
2
1
1
0.125
4
2
1
4
2
16
16
8
32
8
0.5
0.25
8
ND
128
8
4
16
16
4
2
1
ND
32
8
16
2
1
1
0.03
0.03
1
ND
8
0.5
0.5
1
2
1
1
1
64
64
2
32
8
128
ND
64
64
64
64
64
32
128
128
128
64
128
ND
64
32
64
128
64
64
128
128
128
32
0.5
ND
128
32
4
32
128
8
64
128
128
1
128
ND
128
128
32
128
128
128
128
128
128
4
1
ND
64
32
4
32
32
16
16
32
32
0.25
0.25
ND
256
128
64
128
128
64
7
8a
8b
8c
8d
8e
8f
8g
8h
AZM
CLA
2
4
128
16
8
4
8
64
4
2
64
32
32
8
16
32
256
128
64
256
256
256
256
8
0.03
0.03
32
64
0.25
32
a
S. aureus ATCC25923: erythromycin-susceptible strain.
E. coli ATCC25922: penicillin-susceptible strain.
S. pyogenes: erythromycin-susceptible strain isolated clinically.
P. aeruginosa ATCC27853: penicillin-susceptible strain.
B. subtilis ATCC9372: erythromycin-susceptible strain.
S. epidermidis: penicillin-resistant strain isolated clinically, not characterized.
S. aureus ATCC29213: methicillin-resistant strain.
S. pneumoniae B1: erythromycin-resistant strain encoded by the ermB gene.
b
c
d
e
f
g
h
i
S. pneumoniae A22072: erythromycin-resistant strain encoded by the mefA gene.
S. pneumoniae AB11: erythromycin-resistant strain encoded by the ermB and mefA genes.
S. pyogenes R1: erythromycin-resistant strain isolated clinically.
j
k
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M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
5
active compound 4g showed 8-fold more potent antibacterial ac-
tivity against resistant erythromycin-resistant S. pyogenes R1 than
references. However, all of compounds 4a-h failed to show better
antibacterial activity than AZM against four susceptible strains of
S. aureus ATCC 25923, S. pyogenes, P. aeruginosa ATCC27853,
B. subtilis ATCC9372 and two resistant strains of penicillin-resistant
S. epidermidis and methicillin-resistant S. aureus.
11,12-Cyclic carbonate descladinosylazithromycin 3-O-ary-
lalkylcarbamoyl derivatives 5a-m showed obviously increased ac-
tivity against four types of resistant strains. Among them, compound
5a was the most effective against erythromycin-resistant
S. pneumoniae B1 and S. pyogenes R1, showing 16- and 32-fold bet-
ter antibacterial activity than references, respectively. In addition,
S. epidermidis, superior to references (0.25
m
g/mL) and compounds
5l, 6f and 6g also exhibited potent antibacterial activity with the
same MIC values of 0.5 g/mL against resistant S. epidermidis, com-
m
parable to the references. In remarkable contrast, none of the com-
pounds showed improved antibacterial activity against methicillin-
resistant S. aureus compared with AZM and CLA.
Surprisingly, most of the tested compounds showed significantly
improved activity compared with AZM and CLA against resistant
S. pyogenes and all the three phenotypes of resistant S. pneumoniae.
For instance, the most active compound 6h (1
S. pneumoniae expressing the ermB gene, exhibited 256-fold
enhanced activity than the references, and compounds 6f (0.5 g/
mL) and 6g (0.25 g/mL) displayed the most excellent activity
mg/mL) against
m
m
compounds 5l (0.25
m
g/mL) and 5c (32
m
g/mL) were the most active
against S. pneumoniae expressing the mefA gene, which were 8- and
16-fold better than that of azithromycin. Besides, compounds 5g-i,
5m and 8b also demonstrated strong activity against S. pneumoniae
against penicillin-resistant S. epidermidis and methicillin-resistant
S. aureus respectively, equivalent to CLA. As for other susceptible
S. aureus, E. coli, S. pyogenes, P. aeruginosa and B. subtilis, however, this
series did not show notably improved antibacterial activity
compared with references. The above results indicated that intro-
duction of the 3-O-arylalkylcarbamoyl group could result in better
binding to the ribosomes of macrolide-resistant bacteria.
In the series of 11,3-di-O-arylalkylcarbamoyl descladinosylazi-
thromycin derivatives 6a-h, some compounds showed potent anti-
bacterial activity superior or equal to that of AZM against susceptible
E. coli, S. pyogenes, and B. subtilis. For example, compounds 6f-h
demonstrated significantly improved antibacterial activity against
S. pneumoniae expressing the ermB gene, the mefA gene, and the
ermB and mefA genes, showing 8-e256-fold better activity than
references. As for susceptible S. aureus ATCC 25923 and P. aeruginosa
ATCC 27853 and resistant S. aureus ATCC 29213, this series did not
present antibacterial activity equal to AZM. The above results clearly
indicated that introduction of an arylalkylcarbamoyl group into the
11-position of the 3-O-arylalkylcarbamoyl derivatives dramatically
enhanced their antibacterial activity against the erm-resistant
S. pneumoniae and the mef-resistant S. pneumoniae.
expressing the mefA gene, with MICvalues of1e2
compounds 5c and 6h shared the identical activity with the MIC
value of 1 g/mL against S. pneumoniae expressing the ermB and
mefA genes, which was 256 and 128-fold better than that of AZM
(256 g/mL) and CLA (128 g/mL), respectively. As for erythromycin-
resistant S. pyogenes, compound 5awas effective (8 g/mL), showing
32-fold higher activity than references (256 g/mL).
mg/mL. In addition,
m
m
m
m
m
In particular, compound 6f with the C-11 arylalkylcarbamoyl
group displayed 8-, 16-fold more potent activity than its precursor
5b against erm-resistant S. pneumoniae expressing the ermB gene
and the mefA gene, respectively, and compounds 6g (0.25
mg/mL)
with the C-11 arylalkylcarbamoyl group exhibited 16-fold greater
activity than its precursor 5c (4
expressing the mefA gene.
mg/mL) against S. pneumoniae
On the basis of all of results, we speculated that the C-11-
arylalkylcarbamoyl side chain could interact with the nucleotide
A752 directly in domain II of the 23S rRNA, and the 3-O-ary-
lalkylcarbamoyl side chain could bind to the nucleotide G2505,
C2610 or C2611 in domain V in addition to the interaction of its
descladinosylazithromycin nucleus with the nucleotide A2058 in
domain V, which brought about an additional affinity for the
resistant ribosome, resulting in increased activity against the
resistant bacteria.
Moreover, we performed a molecular docking study on com-
pound 5b using the SYBYL-X 2.0to further understand the inter-
action of 3-O-carbamoyl descladinosylazithromycin derivatives
with 23S rRNA of 50S ribosomal subunit. We retrieved the crystal
structure of the 50S ribosomal subunit of Deinococcus radiodurans
in complex with azithromycin from the deposited PDB structure
1nwy. The binding mode of 5b was listed in Fig. 2. The result
indicated that a hydrogen bond was formed between the 3-O-car-
bamoyl of compound 5b and C2589 (C2610 in E. coli).
11,12-Cyclic carbonate descladinosylazithromycin 20-O-ary-
lalkylcarbamoyl derivatives 8a-h exhibited increased activity
against S. pneumoniae expressing the ermB gene, the mefA gene and
the ermB and mefA genes, and erythromycin-resistant S. pyogenes
R1, as well as medium antibacterial activity against susceptible
S. aureus ATCC 25923, S. pyogenes, B. subtilis ATCC9372 and
penicillin-resistant S. epidermidis and methicillin-resistant S. aureus
compared with references. Particularly, compounds 8e and 8a
presented the best antibacterial activity against Gram-negative
E. coli ATCC25922 and P. aeruginosa ATCC27853, respectively in all
of the 40 tested compounds. This indicated that the introduction of
20-O-arylalkylcarbamoyl group could enhance antibacterial activity
against Gram-negative bacteria.
On the whole, a majority of the target compounds showed
moderate to favorable activity against six kinds of susceptible
strains. Among them, compound 6g was found to have the most
5. Conclusion
potent antibacterial activity (1
and compounds 3, 4a and 8e were the most effective (32
against E. coli ATCC25922 comparable to CLA (32 g/mL) and AZM
(64 g/mL). Additionally, compounds 4a, 5a, 5c-5d, 5g-i, 5m, 6f-g
and 8a-b also displayed outstanding activity against susceptible
S. pyogenes, with MIC values between 0.03 and 0.5 g/mL. Com-
pound 6h was the most effective (0.5 g/mL) against B. subtilis
mg/mL) against S. aureus ATCC25923
Novel 20, 3-di-O-substituted 11,12 cyclic carbonate, 3-O-ary-
lalkylcarbamoyl 11,12 cyclic carbonate, 3,11-O-arylalkylcarbamoyl,
and 20-O-arylalkylcarbamoyl descladinosylazithromycin de-
rivatives were designed, synthesized and tested for their in vitro
antibacterial activity against various phenotypes of Gram-positive
and Gram-negative bacteria species. Generally, the majority of the
target compounds displayed moderate to favorable activity against
six kinds of susceptible strains, and significantly improved activity
against all of the four erythromycin-resistant strains, S. pneumoniae
B1, S. pneumoniae A22072, S. pneumoniae AB11 and S. pyogenes R1
compared with references. 20-O-Arylalkylcarbamoyl 11,12-cyclic
carbonate derivatives 8e and 8a presented the best antibacterial
activity against Gram-negative E. coli ATCC25922 and P. aeruginosa
ATCC27853, respectively, in all of the 40 target compounds.
m
g/mL)
m
m
m
m
ATCC9372, showing 2-fold higher activity than AZM. Unfortunately,
only compound 8a among all of the target compounds exhibited
similar activity to AZM against P. aeruginosa ATCC27853.
On the other hand, compound 6h with the 4-
methoxylphenylcarbamoylaryl group at the 3-position and the n-
hexylcarbamoyl group at the 11-position exerted the highest anti-
bacterial activity (0.125
mg/mL) against penicillin-resistant
Please cite this article in press as: M. Yan, et al., Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives,
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6
M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
Fig. 2. The stereo view of the docking poses of 5b. The gray and color moiety represents compound 5b. The dotted yellow line represents hydrogen bond. The fine lines represents
nucleotides. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Compound 5a possessed potent activity (8
erythromycin-resistant S. pyogenes, showing 32-fold higher activity
than references (256 g/mL). Compound 6h exhibited the highest
antibacterial activity against susceptible B. subtilis ATCC9372
(0.5 g/mL), penicillin-resistant S. epidermidis (0.125 g/mL), the
erm-resistant S. pneumoniae (1 g/mL), the erm and mef-resistant
S. pneumoniae (1 g/mL). Besides, 11,3-O-arylalkylcarbamoyl de-
m
g/mL) against
instrument (Applied Biosystems, Connecticut, USA). Melting points
are uncorrected and were determined on an X-6 melting point
apparatus (Beijing Tianchengwode Biotech Co. Ltd, Beijing, China).
AZM was used as starting material from Nexchem Pharmaceutical
Co. Ltd.
m
m
m
m
m
6.1. 20-O-Acetyl-3-O-descladinosylazithromycin (2)
rivatives 6f-g showed better antibacterial activity than 11,12-cyclic
carbonate 3-O-arylalkylcarbamoyl derivatives 5b-c against the
erm-resistant S. pneumoniae and the mef-resistant S. pneumoniae.
The molecular docking study indicated that the 3-O-ary-
lalkylcarbamoyl side chain in the descladinosylazithromycin nu-
cleus could interact with the cavity formed by G2505, C2610 and
C2611 in domain V, resulting in a higher affinity to bacterial ribo-
somes. The above findings demonstrated that introduction of the C-
11 arylalkylcarbamoyl side chain dramatically enhanced antibac-
terial activity against erythromycin-resistant strains.
To a solution of azithromycin (2.0 g, 2.67 mmol) in absolute
ethanol (20 mL) at room temperature was added dropwise 1 M HCl
(9 mL). The resulting solution was allowed to stir for 20 h at the
same temperature. And then, the reaction solution was neutralized
to pH value 10.5e11.0 with 1 M sodium hydroxide and stirred for
2 h at the room temperature. The resulting precipitate was filtered,
washed with cool water, dried to afford 1.1 g (69%) of 3-O-descla-
dinosylazithromycin as a white solid: mp 138e141 ꢀC, Rf ¼ 0.3
(dichloromethane/methanol, 10:1, v/v).
To
a
solution of 3-O-descladinosylazithromycin (1.0 g,
1.69 mmol) in dichloromethane (10 mL) at room temperature was
added acetic anhydride (0.33 mL, 3.50 mmol) and Et3N (1.00 mL,
7.20 mmol). The resulting solution was allowed to stir for 24 h at
the same temperature. The reaction was quenched with saturated
NaHCO3 (20 mL) and the aqueous layer was extracted with
dichloromethane (3 ꢁ 10 mL). The combined organic layers were
dried over anhydrous Na2SO4, filtered, and concentrated in vacuum,
dried to afford 0.8 g (75%) mp 143e145 ꢀC; Rf ¼ 0.41 (dichloro-
methane/methanol, 10:1).
6. Experimental
All necessary solvents were purified prior to use, unless noted
otherwise. Reactions were monitored by thin-layer chromatography
(TLC) using 0.25-mm pre-coated silica gel plates (Qingdong
Yumingyuan silica gel reagent factory, Shandong, China, YUYUAN).
Flash chromatography was performed with the indicated solvents
using silica gel 60 (particle size 0.040e0.063 mm, Qingdong
Yumingyuan silica gel reagent factory, Shandong, China, YUYUAN).
Infrared spectra were recorded on KBr pellets using Nicolet Nexus
470FT-IR spectrometer (Wisconsin, USA). 1H NMR spectra were
recorded on Bruker Avance DRX 600 spectrometer (Bruker, Swit-
zerlands) at ambient temperature (TMS as internal standard of
chemical shifts). Mass spectra were recorded on API 4000
6.2. 20-O-Acetyl-3-O-acylimidazolyl descladinosylazithromycin
11,12-cyclic carbonate (3)
To a solution of 2 (0.6 g, 0.95 mmol) in toluene (8 mL) was added
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M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
7
Et3N (0.62 mL, 4.50 mmol) and CDI (0.62 g, 3.83 mmol). The
resulting solution was heated to 55 ꢀC and stirred at the same
temperature for 72 h. The reaction was quenched with saturated
NaHCO3 (20 mL) and the aqueous layer was extracted with toluene
(3 ꢁ 10 mL). The combined organic layers were dried over anhy-
drous Na2SO4, filtered, and concentrated in vacuum. The residue
was purified by flash column chromatography (dichloromethane/
methanol, 20:1) to afford 0.7 g (75%) of 3 as a white solid: mp
149e152 ꢀC; Rf ¼ 0.45 (dichloromethane/methanol, 10:1).
descladinosylazithromycin derivatives (8a-h) by coupling with the
corresponding amines in the presence of pyridine hydrochloride at
room temperature for 6e8 days. The crude product was purified by
flash chromatography (dichloromethane/methanol, 50:1, v/v),
Rf ¼ 0.75 (dichloromethane/methanol, 10:1). The yields ranged
from 60% to 75%.
6.6.1. 11,12-Carbonate 20-O-acetyl-3-O-acylimidazolide
descladinosylazithromycin derivative (3)
White solid, yield 62%, mp 149e152 ꢀC, TLC Rf
¼
0.45
6.3. General methods for the preparation of 11,12-cyclic carbonate
descladinosylazithromycin 20-O-acetyl-3-O-arylalkylcarbamoyl
derivatives (4a-h)
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 8.23 (s, 1H),
7.52 (s, 1H), 7.19e7.15 (m, 1H), 5.71 (m,, 1H), 4.69 (m, 2H), 4.02 (m,
1H), 3.58 (m,1H), 3.28e3.07 (m,1H), 2.86 (m,1H), 2.65 (m,1H), 2.37
(m, 1H), 2.27 (s, 4H), 2.19 (s, 7H), 2.09 (s, 4H), 1.51 (m, 2H), 1.44 (s,
3H), 1.33e1.19 (m, 9H), 1.09 (m, 10H), 0.91 (s, 7H). MS (ESI) m/z
calcd. for C37H60N4O12 752.4; found [M þ H]þ 753.7.
Compound 3 were readily converted to 11,12-cyclic carbonate
descladinosylazithromycin
20-O-acetyl-3-O-arylalkylcarbamoyl
derivatives (4a-h) by coupling with the corresponding amines in
the presence of pyridine hydrochloride at room temperature for
6e8 days in yields ranging from 58% to 69%. Rf ¼ 0.7 (dichloro-
methane/methanol, 10:1).
6.6.2. 11,12-Carbonate 20-O-acetyl-3-O-(phenyl)carbamoyl
descladinosylazithromycin derivative (4a)
White solid, yield 62%, mp 120e123 ꢀC, TLC Rf
¼
0.7
(CH2Cl2:MeOH ¼ 10:1);1H NMR (400 MHz, CDCl3)
d 7.47 (s, 2H),
6.4. General methods for the preparation of 11,12-cyclic carbonate
descladinosylazithromycin 3-O-arylalkylcarbamoyl derivatives (5a-
m)
7.33 (s, 2H), 7.07 (s, 1H), 6.15 (s, 1H), 5.11e5.08 (m, 1H), 4.71 (s, 1H),
4.62 (s, 1H), 4.25 (s, 1H), 3.60e3.57 (s, 1H), 3.13 (s, 1H), 2.90 (s, 1H),
2.83 (d, J ¼ 5.9 Hz, 1H), 2.51 (s, 1H), 2.35 (s, 1H), 2.27 (s, 4H),
2.18e2.15 (m, 11H), 2.06 (s, 2H), 2.02 (s, 1H), 1.87 (s, 2H), 1.42 (s, 4H),
1.25 (d, J ¼ 5.3 Hz, 5H), 1.21 (s, 4H), 1.17 (s, 1H), 1.06 (s, 6H), 0.98 (d,
J ¼ 5.8 Hz, 3H), 0.91 (d, J ¼ 6.0 Hz, 7H). MS (ESI) m/z calcd. for
A solution of the above crude product 4 in methanol (15 mL) was
heated to 50 ꢀC and stirred for 12 h at the same temperature. After
concentrating the reaction solution in vacuo, the residue was pu-
rified by flash chromatography (dichloromethane/methanol, 40:1,
v/v) to afford the desired products 5a-m.
C
40H63N3O12 777.4; found [M þ H]þ 778.7.
6.6.3. 11,12-Carbonate 20-O-acetyl-3-O-(2-methylphenyl)
carbamoyl descladinosylazithromycin derivative (4b)
White solid, yield 78%, mp 124e126 ꢀC, TLC Rf
6.5. General methods for the preparation of 11,3-di-O-
arylalkylcarbamoyl descladinosylazithromycin derivatives (6a-i)
¼
0.7
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.24e6.21 (m,
Compound
5
were readily converted to 11,3-di-O-ary-
4H), 4.62 (s, 1H), 3.61 (s, 1H), 2.94 (s, 1H), 2.84 (s, 1H), 2.32 (s, 4H),
2.28 (s, 5H), 2.23 (s, 1H), 2.20 (s, 1H), 2.13 (s, 3H), 2.06 (s, 2H), 2.02
(s, 3H), 1.45e1.43 (m, 3H), 1.26 (s, 17H), 1.15 (s, 2H), 1.08 (s, 5H), 1.00
(s, 2H), 0.91 (s, 8H). MS (ESI) m/z calcd. for C41H65N3O12 791.5;
found [M þ H]þ 792.7.
lalkylcarbamoyl descladinosylazithromycin derivatives (6a-i) by
coupling with the corresponding amines in the presence of pyri-
dine hydrochloride at room temperature for 6e8 days. The crude
product was purified by flash chromatography (dichloromethane/
methanol, 6:1, v/v), Rf ¼ 0.2 (dichloromethane/methanol, 10:1). The
yields ranged from 45% to 54%.
6.6.4. 11,12-Carbonate 20-O-acetyl-3-O-(2-fluorophenyl)carbamoyl
descladinosylazithromycin derivative (4c)
6.6. General methods for the preparation of (8a-h)
White solid, yield 66%, mp 120e122 ꢀC, TLC Rf
¼
0.7
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 8.20e8.05 (m,
To a solution of azithromycin (2.0 g, 2.67 mmol) in absolute
ethanol (20 mL) at room temperature was added dropwise 1 M HCl
(9 mL). The resulting solution was allowed to stir for 20 h at the
same temperature. And then, the reaction solution was neutralized
to pH value 10.5e11.0 with 1 M sodium hydroxide and stirred for
2 h at the room temperature. The resulting precipitate was filtered,
washed with cool water, dried to afford 1.1 g (69%) of 3-O-descla-
dinosylazithromycin as a white solid: mp 138e141 ꢀC, Rf ¼ 0.3
(dichloromethane/methanol 10:1, v/v).
1H), 7.57e7.37 (m, 1H), 7.18e7.12 (m, 1H), 7.10e7.08 (m, 1H),
7.05e7.03 (m, 1H), 5.19e5.12 (m, 1H), 4.95e4.93 (m, 1H), 4.80e4.77
(m, 1H), 4.55e4.36 (m, 1H), 4.22e4.05 (m, 2H), 3.56e3.34 (m, 1H),
3.09e2.82 (m, 3H), 2.64e2.52 (m, 1H), 2.30e2.27 (m, 3H),
2.22e2.18 (m, 3H), 2.13e2.05 (m, 5H), 2.03e2.01 (m, 2H), 1.98e1.90
(m, 2H), 1.86e1.82 (m, 1H), 1.76e1.71 (m, 3H), 1.66e1.63 (m, 1H),
1.51e1.46 (m, 2H), 1.38e1.20 (m, 8H), 1.17e1.12 (m, 2H), 1.09e0.83
(m, 14H). HRMS (AP-ESI) m/z calcd for C40H62FN3O12 [M þ H]þ
796.4390, found 796.4448.
To
a solution of 3-O-descladinosylazithromycin (0.56 g,
0.95 mmol) in toluene (8 mL) was added Et3N (0.62 mL, 4.50 mmol)
and CDI (0.62 g, 3.83 mmol). The resulting solution was heated to
55 ꢀC and stirred at the same temperature for 48 h. The reaction
was quenched with saturated NaHCO3 (20 mL) and the aqueous
layer was extracted with toluene (3 ꢁ 10 mL). The combined
organic layers were dried over anhydrous Na2SO4, filtered, and
concentrated in vacuum. The residue was purified by flash column
chromatography (dichloromethane/methanol, 40:1) to afford 0.15 g
(75%) of 7 as a white solid: mp 148e150 ꢀC; Rf ¼ 0.6 (dichloro-
methane/methanol, 10:1).
6.6.5. 11,12-Carbonate 20-O-acetyl-3-O-(3-methoxylphenyl)
carbamoyl descladinosylazithromycin derivative (4d)
White solid, yield 56%, mp 121e123 ꢀC, TLC Rf
¼
0.7
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.23e7.15 (m,
1H), 7.10 (s, 1H), 6.95 (s, 1H), 6.63 (s, 1H), 5.10 (s, 1H), 4.62 (s, 1H),
4.24 (s,1H), 3.81 (s, 3H), 3.60 (s,1H), 2.83 (s,1H), 2.39 (s,1H), 2.34 (s,
1H), 2.27 (s, 3H), 2.20 (s, 5H), 2.15 (s, 2H), 2.06 (s, 1H), 1.87 (s, 1H),
1.47 (s, 1H), 1.42 (s, 3H), 1.25 (s, 14H), 1.21 (s, 4H), 1.10e1.06 (s, 6H),
0.97 (d, J ¼ 5.7 Hz, 2H), 0.91 (s, 8H). HRMS (AP-ESI) m/z calcd for
Compound 7 were readily converted to 20-O-arylalkylcarbamoyl
C
41H65N3O13 [M þ H]þ 808.4589, found 808.4578.
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8
M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
6.6.6. 11,12-Carbonate 20-O-acetyl-3-O-(benzyl)carbamoyl
descladinosylazithromycin derivative (4e)
CDCl3) d 177.93,174.13,153.49,153.08,139.12,138.14,129.03,123.98,
118.51, 114.98, 104.17, 86.43, 85.53, 84.80, 79.51, 75.83, 72.94, 70.68,
69.25, 68.16, 65.66, 61.89, 43.27, 42.17, 40.06, 35.82, 35.04, 28.31,
26.20, 25.86, 21.76, 21.53, 21.33, 20.98, 15.76, 13.47, 10.12, 9.45, 4.98.
MS (ESI) m/z calcd. for C39H63N3O11 749.9; found [M þ H]þ 750.6.
White solid, yield 58%, mp 122e124 ꢀC, TLC Rf
¼
0.7
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.33 (s, 3H),
7.30 (s, 2H), 4.91e4.83 (m, 1H), 4.53 (s, 1H), 4.48e4.44 (m, 2H),
4.31e4.28 (m, 1H), 4.03e4.01 (m, 1H), 3.59e3.51 (m, 1H), 3.25e3.15
(m, 1H), 3.00 (s, 1H), 2.84 (s, 1H), 2.65e2.52 (m, 3H), 2.36e2.24 (m,
7H), 2.20 (s, 2H), 2.06 (s, 2H), 2.03 (s, 2H), 1.95e1.90 (m, 2H),
1.80e1.75 (m, 2H), 1.67 (s, 1H), 1.46e1.40 (m, 3H), 1.26 (s, 10H),
1.16e1.15 (m, 3H), 1.09e1.06 (m, 5H), 0.93e0.88 (m, 7H). MS (ESI)
m/z calcd. for C41H65N3O12 791.5; found [M þ H]þ 792.9.
6.6.12. 3-O-(2-Methylphenyl)carbamoyl descladinosylazithromycin
11,12-cyclic carbonate (5c)
White solid, yield 66%, mp 115e118 ꢀC, TLC Rf
¼
0.6
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.24e6.98 (m,
4H), 5.11e5.09 (m, 1H), 4.70e4.64 (m, 1H), 4.12e4.11 (m, 1H), 3.61
(s, 1H), 3.26e3.15 (s, 2H), 2.96e2.84 (m, 2H), 2.40e2.04 (m, 19H),
1.96e1.81 (m, 3H), 1.62e1.50 (m, 2H), 1.44 (s, 2H), 1.26e1.24 (m,
6H), 1.19e1.04 (m, 12H), 0.96e0.89 (m, 7H). 13C NMR (100 MHz,
6.6.7. 11,12-Carbonate 20-O-acetyl-3-O-(n-pentyl)carbamoyl
descladinosylazithromycin derivative (4f)
White solid, yield 72%, mp 132e134 ꢀC, TLC Rf
¼
0.7
CDCl3) d 174.11, 153.34, 136.04,130.45, 130.22, 127.11, 126.62, 123.66,
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d
5.24 (s, 1H),
121.43, 104.06, 86.45, 84.84, 79.76, 75.90, 72.99, 70.48, 69.55, 69.29,
68.16, 65.83, 61.91, 43.34, 42.28, 40.09, 36.90, 36.08, 34.94, 28.36,
26.14, 25.84, 21.83, 21.33, 21.02, 17.79, 15.71, 13.55, 10.12, 9.49, 5.04.
MS (ESI) m/z calcd. for C39H63N3O11 749.4; found [M þ H]þ 750.6.
4.90e4.83 (s, 2H), 2.19 (s, 4H), 2.05 (s, 4H), 1.93 (s, 1H), 1.80 (s, 1H),
1.69 (s, 1H), 1.47 (s, 4H), 1.31 (d, J ¼ 1.0 Hz, 5H), 1.25 (s, 8H), 1.19e1.18
(m, 3H), 1.07 (s, 5H), 0.90 (s, 12H).
13C NMR (100 MHz, CDCl3)
d 181.43, 174.69, 155.95, 103.53,
99.74, 91.87, 86.34, 86.16, 85.83, 74.15, 73.48, 73.33, 70.58, 69.28,
65.97, 60.80, 60.65, 50.19, 43.66, 41.16, 40.34, 40.25, 38.46, 36.37,
29.91, 29.71, 29.00, 22.38, 22.34, 21.79, 21.19, 21.11, 20.99, 15.41,
14.99, 14.01, 12.32, 10.07, 9.65. MS (ESI) m/z calcd. for C39H69N3O12
771.5; found [M þ H]þ 773.7.
6.6.13. 3-O-(2-Fluorophenyl)carbamoyl descladinosylazithromycin
11,12-cyclic carbonate (5d)
White solid, yield 69%, mp 110e112 ꢀC, TLC Rf
¼
0.6
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.54e7.01 (m,
4H), 5.38e4.93 (m, 4H), 4.49e4.14 (m, 2H), 3.82e3.71 (m, 1H),
3.56e2.82 (m, 4H), 2.42e1.89 (m,14H),1.80e1.44 (m, 7H),1.33e1.10
(m, 10H), 1.11e0.81 (m, 13H). MS (ESI) m/z calcd. for C38H60FN3O11
753.4; found [M þ H]þ 754.7.
6.6.8. 11,12-Carbonate 20-O-acetyl-3-O-(n-hexyl)carbamoyl
descladinosylazithromycin derivative (4g)
White solid, yield 67%, mp 131e133 ꢀC, TLC Rf
¼
0.7
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d
4.91e4.83 (m,
6.6.14. 3-O-(3-Methoxyphenyl)carbamoyl
2H), 3.71e3.68 (m, 1H), 3.50e3.47 (m, 1H), 3.28e3.26 (m, 1H), 2.75
(s, 2H), 2.66e2.58 (m, 4H), 2.37 (s, 2H), 2.19 (s, 2H), 2.10 (s, 1H), 2.03
(d, J ¼ 8.1 Hz, 4H), 1.67 (s, 1H), 1.60 (s, 1H), 1.51 (s, 2H), 1.46 (s, 1H),
1.42 (s, 1H), 1.39 (s, 1H), 1.26 (s, 26H), 1.08 (s, 5H), 0.96 (s, 1H), 0.94
(s, 1H), 0.88 (s, 10H). HRMS (AP-ESI) m/z calcd for C40H71N3O12
786.5034, found [M þ H]þ 786.5107.
descladinosylazithromycin 11,12-cyclic carbonate (5e)
White solid, yield 60%, mp 111e113 ꢀC, TLC Rf
¼
0.6
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.71e7.52 (m,
1H), 7.20e7.14 (m, 1H), 7.00e6.96 (m, 1H), 6.63e6.56 (m, 1H),
5.23e5.07 (m, 2H), 4.63e4.53 (m, 1H), 4.23e4.16 (m, 1H), 3.81 (s,
3H), 3.55 (m, 1H), 3.28e3.18 (m, 2H), 2.89e2.81 (m, 2H), 2.49e2.14
(m, 10H), 2.06e1.97 (m, 2H), 1.94e1.82 (m, 2H), 1.65e1.60 (m, 1H),
1.47e1.43 (m, 3H), 1.35e1.33 (m, 1H), 1.31e1.20 (m, 10H), 1.17e0.83
(m,17H). MS (ESI) m/z calcd. for C39H63N3O12 765.4; found [M þ H]þ
766.5.
6.6.9. 11,12-Carbonate 20-O-acetyl-3-O-(benzyl)N-
methylcarbamoyl descladinosylazithromycin derivative (4h)
Black solid, yield 43%, mp 121e123 ꢀC, TLC Rf
¼
0.7
(CH2Cl2:MeOH ¼ 10:1); MS (ESI) m/z calcd. for C41H65N3O12 791.5;
found [M þ H]þ 792.8.
6.6.15. 3-O-(Benzyl)N-methylcarbamoyl descladinosylazithromycin
11,12-cyclic carbonate (5f)
6.6.10. 3-O-(Phenyl)carbamoyl descladinosylazithromycin 11,12-
White solid, yield 55%, TLC Rf ¼ 0.6 (CH2Cl2:MeOH ¼ 10:1); 1H
cyclic carbonate (5a)
NMR (400 MHz, CDCl3) d 7.513e7.510 (m, 2H), 7.51e7.10 (m, 5H),
White solid, yield 53%, mp 118e120 ꢀC, TLC Rf
¼
0.6
5.69e5.66 (m, 1H), 5.09e5.06 (m, 1H), 4.72e4.69 (m, 2H),
4.03e4.01 (m, 1H), 3.61e3.58 (m, 1H), 3.18e3.12 (m, 1H), 2.88e2.83
(m, 2H), 2.36e2.35 (m, 1H), 2.26 (s, 4H), 2.21 (s, 4H), 2.20 (s, 1H),
2.09 (s, 3H), 2.08 (s, 1H),1.51 (s, 1H),1.49 (s, 1H),1.43 (m, 3H),1.26 (s,
2H), 1.24 (s, 3H), 1.22 (s, 3H), 1.19e1.18 (m, 1H), 1.12 (s, 2H), 1.11 (s,
2H), 1.07 (s, 4H), 1.058e1.055 (m, 3H), 0.93e0.90 (m, 8H), 0.89 (s,
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.58e7.02 (m,
5H), 5.24e5.21 (m, 1H), 5.12e5.07 (m, 1H), 4.62 (s, 1H), 4.30e4.24
(m, 1H), 3.82 (s, 4H), 3.57 (s, 1H), 3.30e3.27 (m, 1H), 3.20e3.11 (m,
1H), 2.88e2.82 (m, 2H), 2.51 (s, 1H), 2.44 (s, 3H), 2.38e2.35 (m, 1H),
2.70 (s, 2H), 2.21 (s, 1H), 2.09 (s, 1H), 2.01 (s, 2H), 1.90e1.88 (m, 2H),
1.79 (s,1H),1.61 (s,1H),1.50 (s,1H),1.45e1.42 (m, 3H),1.32e1.22 (m,
8H), 1.17e1.15 (m, 2H), 1.14 (s, 1H), 1.09e1.07 (m, 4H), 1.04 (s, 1H),
0.98e0.96 (m, 1H), 0.91e0.90 (m, 6H). MS (ESI) m/z calcd. for
1H). 13C NMR (100 MHz, CDCl3)
d 174.05, 160.36, 153.31, 139.41,
129.88, 110.00, 109.07, 103.81, 86.22, 84.85, 79.59, 75.72, 72.85,
70.45, 69.04, 68.23, 65.67, 61.99, 55.33, 43.15, 42.11, 39.99, 35.90,
35.09, 31.98, 29.65, 29.38, 28.44, 26.06, 25.85, 22.67, 21.75, 21.33,
20.97, 15.78, 14.15, 13.46, 10.12, 9.46, 4.96. MS (ESI) m/z calcd. for
C
38H61N3O11 735.4; found [M þ H]þ 736.8.
6.6.11. 3-O-(3-Methylphenyl)carbamoyl descladinosylazithromycin
11,12-cyclic carbonate (5b)
C
40H65N3O11 763.5; found [M þ H]þ 764.8.
White solid, yield 57%, mp 110e112 ꢀC, TLC Rf
¼
0.6
6.6.16. 3-O-(2-Chlorophenyl)carbamoyl descladinosylazithromycin
11,12-cyclic carbonate (5g)
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.59e7.52 (m,
1H), 7.34 (s, 1H), 7.20e7.16 (m, 1H), 6.89e6.82 (m, 1H), 6.18 (s, 1H),
5.30e5.21 (m, 1H), 5.11e5.08 (s, 1H), 4.64e4.62 (m, 1H), 4.19e4.14
(m, 1H), 3.55 (s, 1H), 3.27e2.21 (m, 19H), 2.07e1.83 (m, 4H),
1.63e1.59 (m, 2H), 1.53e1.40 (m, 4H), 1.36e1.31 (m, 1H), 1.28e1.21
(m, 6H), 1.19e1.02 (m, 10H), 1.01e0.84 (m, 6H). 13C NMR (100 MHz,
White solid, yield 69%, TLC Rf ¼ 0.6 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3)
d 7.52e6.99 (m, 4H), 5.12e5.08 (m, 1H),
4.64 (s, 1H), 3.62 (s, 1H), 3.29e3.25 (s, 1H), 2.99e2.94 (s, 1H),
2.36e2.35 (m, 2H), 2.30e2.28 (m, 6H), 2.24e2.20 (m, 3H),
2.02e2.01 (m, 2H), 1.65e1.62 (m, 2H), 1.45e1.44 (m, 3H), 1.32 (s,
Please cite this article in press as: M. Yan, et al., Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives,
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M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
9
1H), 1.31e1.30 (m, 1H), 1.26e1.24 (m, 16H), 1.16 (s, 1H), 1.14 (s, 1H),
1.09e1.06 (m, 4H), 0.93e0.88 (m, 7H). MS (ESI) m/z calcd. for
C
154.72, 153.44, 130.96, 128.86, 104.98, 87.04, 76.00, 73.04, 70.26,
60.10, 37.15, 31.94, 31.45, 30.59, 30.47, 30.41, 30.38, 30.21, 29.71,
29.62, 29.37, 26.13, 25.84, 23.77, 22.99, 22.70, 22.47, 21.81, 21.39,
21.07, 21.03, 20.88, 15.85, 15.25, 14.12, 13.73, 10.08, 7.55. MS (ESI) m/
z calcd. for C39H63N3O11 749.4; found [M þ H]þ 750.6.
36H60ClN3O11 769.4; found [M þ H]þ 770.6.
6.6.17. 3-O-(3-Chlorophenyl)carbamoyl descladinosylazithromycin
11,12-cyclic carbonate (5h)
White solid, yield 72%, TLC Rf ¼ 0.6 (CH2Cl2:MeOH ¼ 10:1); 1H
6.6.23. 3-O-(4-Methylphenyl)carbamoyl-11-O-(benzyl)carbamoyl
descladinosylazithromycin (6a)
NMR (400 MHz, CDCl3) d 7.81e7.01 (m, 4H), 5.10e5.08 (m, 1H), 4.62
(s, 1H), 4.22e4.13 (m, 1H), 3.59e3.51 (m, 1H), 3.29e3.19 (m, 2H),
2.86e2.81 (m, 2H), 2.39e2.21 (m, 11H), 2.10e1.83 (m, 5H),
1.68e1.61 (m, 1H), 1.49e1.41 (m, 3H), 1.36e1.18 (m, 11H), 1.15e1.05
(m, 9H), 0.92e0.83 (m, 7H). MS (ESI) m/z calcd. for C36H60ClN3O11
769.4; found [M þ H]þ 770.6.
White solid, yield 45%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3)
d 7.77e7.03 (m, 9H), 4.97e4.90 (m, 1H),
4.66e4.62 (m, 1H), 4.52e4.50 (m, 1H), 4.22e4.15 (m, 1H), 3.83 (s,
1H), 3.41e3.33 (m, 1H), 3.25e3.17 (m, 2H), 2.94e2.85 (m, 4H),
2.45e2.44 (m, 1H), 2.38 (s, 1H), 2.33 (s, 5H), 2.28 (m, 3H), 2.21 (m,
6H), 2.07e2.06 (m, 3H), 2.02e2.01 (m, 1H), 1.95e1.93 (m, 1H),
1.82e1.79 (m, 2H), 1.70e1.63 (m, 2H), 1.49e1.47 (m, 2H), 1.25e1.21
(m, 8H), 1.15 (s, 1H), 1.13 (s, 1H), 1.09e1.06 (m, 5H), 0.93e0.91 (m,
7H). MS (ESI) m/z calcd. for C46H72N4O11 856.5; found [M þ H]þ
857.7.
6.6.18. 3-O-(4-Fluorophenyl)carbamoyl descladinosylazithromycin
11,12-cyclic carbonate (5i)
White solid, yield 66%, TLC Rf ¼ 0.6 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3) d 8.14e6.90 (m, 4H), 5.13e4.98 (m,1H), 4.54
(s, 1H), 4.17e4.16 (m, 1H), 3.48 (s, 1H), 3.24e3.19 (m, 1H), 2.77e2.65
(m, 2H), 2.40e2.10 (m, 10H), 1.99e1.92 (m, 2H), 1.54e1.50 (m, 2H),
1.35 (s, 2H), 1.18e1.10 (m, 19H), 1.05e0.99 (m, 7H), 0.85e0.78 (m,
7H). HRMS (AP-ESI) m/z calcd for C38H60FN3O11 [M þ H]þ 753.4212;
found [M þ H]þ 754.4316.
6.6.24. 3-O-(Phenyl)carbamoyl-11-O-(benzyl)carbamoyl
descladinosylazithromycin (6b)
White solid, yield 55%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3)
d 7.87e7.02 (m, 10H), 5.23e5.20 (m, 1H),
5.09e5.07 (m, 1H), 4.76e4.62 (m, 1H), 4.31e4.25 (m, 1H), 3.95 (s,
1H), 3.64e3.58 (m, 1H), 3.27e3.13 (m, 5H), 2.84e2.82 (m, 2H),
2.442e2.440 (m, 1H), 2.38 (s, 4H), 2.27 (s, 2H), 2.21 (s, 1H),
2.09e2.02 (m, 2H), 1.77e1.72 (m, 1H), 1.608e1.606 (m, 1H),
1.45e1.42 (m, 3H), 1.26e1.22 (m, 15H), 1.14 (s, 3H), 1.07 (s, 5H), 0.90
(s, 7H). MS (ESI) m/z calcd. for C45H70N4O11 842.5; found [M þ H]þ
843.6.
6.6.19. 3-O-(3-Fluorophenyl)carbamoyl descladinosylazithromycin
11,12-cyclic carbonate (5j)
White solid, yield 57%, TLC Rf ¼ 0.6 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3)
d 7.64e6.71 (m, 4H), 5.23e5.07 (m, 1H),
4.69e4.54 (m,1H), 4.26e4.20 (m,1H), 3.28e3.18 (m,1H), 2.84e2.83
(m, 1H), 2.46e2.38 (m, 3H), 2.27e2.20 (m, 3H), 2.06e2.00 (m, 4H),
1.82e1.80 (m, 1H), 1.51e1.43 (m, 3H), 1.25 (s, 15H), 1.23 (s, 2H), 1.22
(s, 1H), 1.15e1.03 (m, 9H), 0.92e0.83 (m, 9H). HRMS (AP-ESI) m/z
calcd for C38H60FN3O11 753.4212; found [M þ H]þ 754.4274.
6.6.25. 3-O-(Phenyl)carbamoyl-11-O-(n-hexyl)carbamoyl
descladinosylazithromycin (6c)
White solid, yield 55%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1); 1H
6.6.20. 3-O-(3-Trifluoromethyl phenyl)carbamoyl
NMR (400 MHz, CDCl3) d 7.87e7.01 (m, 5H), 5.03e5.00 (m, 1H),
descladinosylazithromycin 11,12-cyclic carbonate (5k)
4.25e4.23 (m, 1H), 3.64e3.61 (m, 1H), 3.38e3.36 (m, 2H),
3.150e3.146 (m, 2H), 2.84e2.81 (m, 1H), 2.43e2.37 (m, 2H), 2.26 (s,
5H), 2.22 (s, 3H), 2.13e2.08 (m, 1H), 2.02e1.95 (m, 2H), 1.85e1.83
(m, 1H), 1.72e1.60 (m, 3H), 1.26 (s, 19H), 1.21 (s, 3H), 1.17 (s, 7H),
1.08e1.07 (m, 3H), 0.99 (s, 3H), 0.88 (s, 9H). MS (ESI) m/z calcd. for
White solid, yield 61%, TLC Rf ¼ 0.6 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3)
d 8.12e7.42 (m, 2H), 7.18e6.72 (m, 2H),
5.35e5.08 (m, 1H), 4.62e4.53 (m, 1H), 4.18e4.16 (m, 1H), 3.56e3.55
(m, 2H), 3.26e3.16 (m, 1H), 2.84e2.83 (m, 1H), 2.38e2.22 (m, 7H),
2.12e2.00 (m, 2H), 1.91e1.84 (m, 2H), 1.68e1.62 (m, 3H), 1.42e1.24
(m, 19H), 1.14e1.08 (m, 5H), 0.90 (s, 10H). MS (ESI) m/z calcd. for
C
44H76N4O11 836.6; found [M þ H]þ 838.8.
C
39H60F3N3O11 803.4; found [M þ H]þ 804.7.
6.6.26. 3-O-(3-Methylphenyl)carbamoyl-11-O-(4-methylbenzyl)
carbamoyl descladinosylazithromycin (6d)
6.6.21. 3-O-(4-Trifluoromethyl phenyl)carbamoyl
White solid, yield 41%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1); 1H
descladinosylazithromycin 11,12-cyclic carbonate (5l)
NMR (400 MHz, CDCl3) d 7.67e7.14 (m, 8H), 5.21e5.08 (m, 1H),
White solid, yield 70%, TLC Rf ¼ 0.6 (CH2Cl2:MeOH ¼ 10:1); 1H
4.80e4.72 (m, 2H), 4.65e4.59 (m, 1H), 4.47e4.38 (m, 1H), 4.18e4.16
(m, 1H), 3.89 (s, 1H), 3.66e3.48 (m, 2H), 3.28e3.13 (m, 2H),
2.99e2.74 (m, 2H), 2.53e2.45 (m, 1H), 2.42e2.37 (m, 4H),
2.33e2.32 (m, 9H), 2.29e2.27 (m, 4H), 2.24e2.14 (m, 2H),
2.08e1.98 (m, 2H), 1.93e1.79 (m, 2H), 1.65e1.59 (m, 2H), 1.53e1.42
(m, 2H), 1.35e1.19 (m, 8H), 1.16e0.97 (m, 9H), 0.94e0.84 (m, 6H).
HRMS (AP-ESI) m/z calcd for C47H74N4O11 870.5354, found [M þ H]þ
871.5370.
NMR (400 MHz, CDCl3)
d 7.83e7.54 (m, 4H), 5.08e5.05 (m, 1H),
4.60 (s, 1H), 3.56 (s, 2H), 3.55 (s, 2H), 2.58 (s, 2H), 2.35 (s, 1H), 2.27
(s, 2H), 2.20 (s, 1H), 1.64 (s, 1H), 1.45 (s, 1H), 1.41 (s, 3H), 1.39 (s, 1H),
1.37 (s, 2H), 1.35 (s, 1H), 1.33 (s, 1H), 1.32 (s, 2H), 1.29 (s, 8H), 1.26 (s,
1H), 1.20 (s, 1H), 1.14 (s, 1H), 1.13 (s, 1H), 1.08 (s, 1H), 1.07 (s, 1H), 1.06
(s, 1H),1.04 (s, 1H), 0.92 (s, 2H), 0.90 (s, 8H), 0.88 (s, 3H). MS (ESI) m/
z calcd. for C39H60F3N3O11 803.4; found [M þ H]þ 804.7.
6.6.22. 3-O-(Phenyl)N-methylcarbamoyl
6.6.27. 3-O-(3-Methylphenyl)carbamoyl-11-O-(4-methoxylbenzyl)
carbamoyl descladinosylazithromycin (6e)
descladinosylazithromycin 11,12-cyclic carbonate (5m)
Black solid, yield 71%, mp 109e112 ꢀC, TLC Rf
¼
0.6
White solid, yield 39%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1); 1H
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d
7.75e7.52 (m,
NMR (400 MHz, CDCl3) d 7.47e6.79 (m, 8H), 5.13e4.92 (m, 1H),
1H), 7.37e7.32 (m, 3H), 7.21e7.11 (m, 1H), 5.12e4.78 (m, 2H),
4.36e4.29 (m, 1H), 4.23e4.17 (m, 1H), 3.76e3.67 (m, 1H), 3.35e3.25
(m, 4H), 2.91e2.81 (m, 2H), 2.40e2.31 (m, 5H), 2.23e2.20 (m, 1H),
2.13 (s, 1H), 2.07e2.02 (s, 2H), 1.95e1.92 (m, 2H), 1.76e1.68 (m, 2H),
1.47e1.41 (m, 2H), 1.33 (s, 1H), 1.29e1.18 (m, 16H), 1.08e1.01 (m,
4.71e4.56 (m, 1H), 4.34e4.18 (m, 3H), 3.97 (s, 1H), 3.77e3.71 (m,
4H), 3.58e3.50 (m, 1H), 3.40 (s, 2H), 3.22e3.14 (m, 1H), 2.89 (s, 1H),
2.81 (s, 1H), 2.38e2.09 (m, 12H), 1.97 (s, 2H), 1.83 (s, 1H), 1.36 (s, 1H),
1.18e0.96 (m, 22H), 0.81 (s, 7H), 0.60e0.59 (m, 2H). 13C NMR
(100 MHz, DMSO)
d 161.68, 160.95, 159.78, 158.66, 158.60, 138.24,
4H), 0.98e0.83 (m, 12H). 13C NMR (100 MHz, CDCl3)
d 170.43,
132.23, 130.87, 130.09, 129.99, 129.53, 129.40, 129.11, 128.92, 126.74,
Please cite this article in press as: M. Yan, et al., Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives,
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10
M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
123.58, 118.97, 115.88, 114.51, 114.37, 114.18, 114.01, 63.85, 60.18,
55.73, 55.63, 55.48, 42.22, 40.66, 40.58, 40.37, 40.16, 39.96, 39.54,
39.33, 31.76, 29.50, 29.22, 29.18, 29.06, 22.57, 21.96, 21.94, 21.72,
21.24, 14.41, 14.10, 10.99. HRMS (AP-ESI) m/z calcd for C47H74N4O12
886.5303, found [M þ H]þ 887.5386.
C
38H61N3O11 735.4; found [M þ H]þ 736.4.
6.6.34. 11,12-Cyclic carbonate 20-O-(2-methylphenyl)carbamoyl
descladinosylazithromycin derivative (8b)
White solid, yield 64%, mp 114e116 ꢀC, TLC Rf
¼
0.75
d 7.24e6.98 (m,
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
6.6.28. 3-O-(3-Methylphenyl)carbamoyl-11-O-(2-chlorobenzyl)
carbamoyl descladinosylazithromycin (6f)
4H), 5.12e5.08 (m, 1H), 4.70e4.59 (m, 1H), 4.14e4.12 (m, 1H), 3.61
(s, 1H), 3.25e3.18 (m, 2H), 2.97e2.84 (m, 2H), 2.40e2.27 (m, 6H),
2.24e2.22 (m, 2H), 2.17e2.15 (m, 5H), 2.08e2.04 (m, 1H), 1.95e1.92
(m, 1H), 1.87e1.81 (m, 1H), 1.67e1.58 (m, 2H), 1.44e1.40 (m, 3H),
1.37e1.24 (m, 10H), 1.19e1.02 (m, 11H), 0.96e0.84 (m, 8H). 13C NMR
White solid, yield 42%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3)
d 7.73e7.71 (m, 3H), 7.55e7.52 (m, 4H),
7.18e7.16 (m, 1H), 4.32e4.29 (m, 7H), 2.83e2.81 (m, 7H), 2.33 (s,
2H), 1.76e1.65 (m, 7H), 1.49e1.49 (m, 10H), 1.29e1.25 (m, 13H),
0.98e0.94 (m, 12H), 0.90e0.86 (m, 3H). HRMS (AP-ESI) m/z calcd
for C46H71ClN4O11 890.4808, found [M þ H]þ 891.4893.
(100 MHz, CDCl3)
d 174.09, 156.15, 153.51, 136.07, 130.44, 127.18,
123.72, 86.46, 84.89, 79.70, 76.50, 75.87, 72.97, 70.48, 69.33, 68.16,
65.78, 61.92, 57.97, 52.40, 43.35, 42.26, 40.08, 36.04, 35.91, 34.95,
30.65, 28.27, 26.13, 25.85, 21.81, 21.34, 21.06, 17.80, 17.36, 15.73,
13.54, 10.13, 9.47, 6.65, 5.03. HRMS (AP-ESI) m/z calcd for
6.6.29. 3-O-(2-Methylphenyl)carbamoyl-11-O-(benzyl)carbamoyl
descladinosylazithromycin (6g)
C
39H63N3O11 [M þ H]þ 749.4463, found [M þ H]þ 750.4575.
White solid, yield 48%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3)
d 7.72e7.70 (m, 1H), 7.55e7.52 (m, 1H),
6.6.35. 11,12-Cyclic carbonate 20-O-(3-methylphenyl)carbamoyl
7.38e7.32 (m, 4H), 7.20e7.14 (m, 2H), 7.05e6.99 (m, 1H), 4.39e4.37
(m, 1H), 4.26e4.14 (m, 2H), 3.69e3.14 (m, 1H), 2.68 (s, 4H),
2.61e2.60 (m, 1H), 2.452e2.446 (m, 1H), 2.33 (s, 3H), 2.04e2.02 (s,
2H), 1.70e1.65 (m, 1H), 1.45e1.44 (m, 1H), 1.43 (s, 1H), 1.41 (s, 1H),
1.39 (s, 1H), 1.33 (s, 2H), 1.32 (s, 1H), 1.30 (s, 1H), 1.29e1.8 (m, 6H),
1.25 (s, 15H), 1.18 (s, 4H), 1.04 (s, 2H), 0.94e0.92 (m, 2H),
0.902e0.896 (m, 3H), 0.88 (s, 3H), 0.86 (s, 1H). HRMS (AP-ESI) m/z
calcd for C46H72N4O11 856.5198, found [M þ H]þ 857.5291.
descladinosylazithromycin derivative (8c)
White solid, yield 60%, mp 110e112 ꢀC, TLC Rf
¼
0.75
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.35e7.02 (m,
4H), 4.65e4.46 (m, 1H), 4.15e4.13 (m, 1H), 3.84e3.70 (m, 1H),
3.56e3.50 (m, 1H), 3.24e3.20 (m, 2H), 2.88e2.85 (m, 1H),
2.38e2.33 (m, 5H), 2.26 (s, 10H), 2.22 (s, 2H), 2.16e2.13 (m, 3H),
2.07e2.01 (m, 3H), 1.63e1.59 (m, 2H), 1.48e1.43 (m, 2H), 1.26 (s,
14H), 1.15e1.14 (m, 1H), 1.11e1.07 (m, 3H), 0.92e0.89 (m, 6H). MS
(ESI) m/z calcd. for C39H63N3O11 749.4; found [M þ H]þ 750.6.
6.6.30. 3-O-(4-Methoxylphenyl)carbamoyl-11-O-(n-hexyl)
carbamoyl descladinosylazithromycin (6h)
6.6.36. 11,12-Cyclic carbonate 20-O-(3-methoxylphenyl)carbamoyl
descladinosylazithromycin derivative (8d)
White solid, yield 33%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1); 1H
NMR (400 MHz, CDCl3)
d 7.54e6.57 (m, 4H), 4.26e4.20 (m, 1H),
White solid, yield 68%,TLC Rf ¼ 0.75 (CH2Cl2:MeOH ¼ 10:1); 1H
3.80 (s, 4H), 3.59e3.55 (m, 1H), 3.49 (s, 1H), 3.21e3.18 (m, 2H),
3.14e3.08 (m, 1H), 3.01e2.97 (m, 3H), 2.72e2.63 (m, 6H), 1.82e1.69
(m, 5H), 1.44e1.43 (m, 1H), 1.42 (s, 1H), 1.40 (s, 1H), 1.31e1.28 (m,
16H), 1.25 (s, 11H), 0.94 (s, 1H), 0.88e0.83 (m, 16H). HRMS (AP-ESI)
m/z calcd for C45H78N4O12 866.5616, found [M þ H]þ 867.5670.
NMR (400 MHz, CDCl3)
d 7.72e6.97 (m, 4H), 4.83e4.71 (m, 2H),
3.72e3.59 (m, 3H), 3.35e3.34 (m, 1H), 2.70e2.64 (m, 2H),
2.53e2.50 (m, 1H), 2.40e2.30 (m, 10H), 2.14 (s, 1H), 2.07e2.06 (m,
4H), 1.92e1.89 (m, 2H), 1.33e1.32 (m, 1H), 1.30e1.23 (m, 13H),
1.14e1.12 (m, 3H), 1.07e1.06 (m, 5H), 0.92e0.88 (m, 10H). HRMS
(AP-ESI) m/z calcd for C39H63N3O12 765.4412, found [M þ H]þ
766.4465.
6.6.31. 3-O-(4-Chlorophenyl)carbamoyl-11-O-(benzyl)carbamoyl
descladinosylazithromycin (6i)
White solid, yield 30%, TLC Rf ¼ 0.2 (CH2Cl2:MeOH ¼ 10:1);
6.6.37. 11,12-Cyclic carbonate 20-O-(3-chlorophenyl)carbamoyl
HRMS (AP-ESI) m/z calcd for
[M þ H]þ 877.4705.
C45H69ClN4O11 876.4651, found
descladinosylazithromycin derivative (8e)
White solid, yield 62%, mp 113e115 ꢀC, TLC Rf
¼
0.75
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 7.75e7.00 (m,
6.6.32. 11,12-Cyclic carbonate 20-O-acylimidazolide
descladinosylazithromycin derivative (7)
4H), 5.01e4.95 (m, 1H), 4.80e4.73 (m, 1H), 4.54e4.45 (m, 1H),
3.93e3.88 (m, 1H), 3.70e3.69 (m 1H), 3.60e3.55 (m, 2H), 3.11e3.03
(m, 4H), 2.92e2.90 (m, 1H), 2.82e2.79 (m, 3H), 2.70e2.69 (m, 1H),
2.57e2.53 (m, 1H), 2.35e2.30 (m, 1H), 2.17e2.13 (m, 1H), 2.03e2.00
(m, 1H), 1.91e1.89 (m, 1H), 1.60e1.59 (m, 3H), 1.54 (s, 1H), 1.47e1.46
(m, 3H), 1.43e1.41 (m, 3H), 1.37e1.35 (m, 3H), 1.25e1.24 (m, 11H),
1.22 (s, 2H), 1.20 (s, 1H), 1.01e0.98 (m, 3H), 0.92e0.88 (m, 4H).
HRMS (AP-ESI) m/z calcd for C38H60ClN3O11 769.3916, found
[M þ H]þ 770.3960.
White solid, yield 21%, mp 148e150 ꢀC, TLC Rf
¼
0.6
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d 8.24e8.22 (m,
1H), 7.53e6.38 (m, 3H), 5.69e5.66 (m, 1H), 5.10e5.06 (m, 1H),
4.71e4.48 (m, 2H), 4.03e3.87 (m,1H), 3.70e3.49 (m,1H), 3.20e3.13
(m, 1H), 2.88e2.61 (m, 2H), 2.39e2.31 (m, 2H), 2.27e2.26 (m, 3H),
2.20e2.16 (m, 6H), 2.09e2.04 (m, 4H), 1.89e1.85 (m, 1H), 1.63e1.58
(m, 1H), 1.49 (s, 1H), 1.44e1.40 (m, 3H), 1.29e1.17 (m, 8H), 1.13e1.10
(m, 3H), 1.08e1.06 (m, 6H), 0.97e0.86 (m, 7H). MS (ESI) m/z calcd.
for C35H58N4O11 710.4; found [M þ H]þ 711.6.
6.6.38. 11,12-Cyclic carbonate 20-O-(4-fluorophenyl)carbamoyl
descladinosylazithromycin derivative (8f)
6.6.33. 11,12-Cyclic carbonate 20-O-(phenyl)carbamoyl
descladinosylazithromycin derivative (8a)
White solid, yield 68%, TLC Rf ¼ 0.75 (CH2Cl2:MeOH ¼ 10:1); 1H
White solid, yield 71%, mp 115e118 ꢀC, TLC Rf
¼
0.75
NMR (400 MHz, CDCl3) d 7.44e7.37 (m, 2H), 7.24e6.98 (m, 2H),
(CH2Cl2:MeOH ¼ 10:1); 1H NMR (400 MHz, CDCl3)
d
7.54e7.04 (m,
5.24e5.08 (m,1H), 4.70e4.47 (m, 2H), 4.26e4.13 (m,1H), 3.93e3.82
(m, 2H), 3.49e3.21 (m, 1H), 2.90e2.80 (m, 1H), 2.38e2.35 (m, 1H),
2.32e2.14 (m, 8H), 2.11e2.00 (m, 3H), 1.92e1.76 (m, 3H), 1.68 (s,
1H), 1.53e1.48 (m, 2H), 1.43 (s, 2H), 1.37e1.17 (m, 14H), 1.13e1.07
(m, 5H), 0.97e0.83 (m, 8H). MS (ESI) m/z calcd. for C38H60FN3O11
753.4; found [M þ H]þ 754.9.
5H), 5.27e5.09 (m, 2H), 4.63 (s, 1H), 4.12e4.10 (m, 1H), 3.60e3.56
(m, 1H), 3.23e3.21 (m, 1H), 2.92e2.84 (m, 2H), 2.39e2.36 (m, 1H),
2.28e2.16 (m, 11H), 2.06e2.00 (m, 2H), 1.91e1.84 (m, 3H), 1.62 (s,
1H), 1.44 (s, 3H), 1.38e1.32 (m, 2H), 1.26 (s, 7H), 1.16e1.14 (m, 3H),
1.10e1.08 (m, 6H), 0.92e0.91 (m, 6H). MS (ESI) m/z calcd. for
Please cite this article in press as: M. Yan, et al., Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives,
European Journal of Medicinal Chemistry (2016), http://dx.doi.org/10.1016/j.ejmech.2016.10.065

M. Yan et al. / European Journal of Medicinal Chemistry xxx (2016) 1e11
11
6.6.39. 11,12-Cyclic carbonate 20-O-(3-fluorophenyl)carbamoyl
dx.doi.org/10.1016/j.ejmech.2016.10.065.
descladinosylazithromycin derivative (8g)
White solid, yield 66%, TLC Rf ¼ 0.75 (CH2Cl2:MeOH ¼ 10:1); 1H
References
NMR (400 MHz, CDCl3)
d 8.03e6.67 (m, 4H), 5.18e5.02 (m, 1H),
4.62e4.42 (m, 1H), 4.25e4.08 (m, 3H), 3.79 (s, 1H), 3.60e3.42 (m,
1H), 2.80e2.74 (m, 1H), 2.31e2.12 (m, 7H), 1.97e1.92 (m, 3H), 1.61
(s, 1H), 1.53e1.49 (m, 3H), 1.36 (s, 2H), 1.18 (s, 18H), 1.05e1.00 (m,
4H), 0.88e0.84 (m, 9H). MS (ESI) m/z calcd. for C38H60FN3O11 753.4;
found [M þ H]þ 754.8.
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descladinosylazithromycin derivative (8h)
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NMR (400 MHz, CDCl3)
d 7.73e6.99 (m, 4H), 5.24e5.08 (m, 1H),
4.69e4.51 (m, 1H), 4.32e4.20 (m, 1H), 3.88 (s, 1H), 2.89e2.53 (m,
2H), 2.39e2.20 (m, 3H), 2.02e1.99 (m, 2H), 1.74e1.68 (m, 3H),
1.65e1.58 (m, 4H), 1.54e1.52 (m, 1H), 1.43 (s, 2H), 1.30e1.22 (m,
26H), 1.14e1.13 (m, 2H), 1.10e1.07 (m, 2H), 1.04e1.00 (m, 1H),
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C
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Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
Please cite this article in press as: M. Yan, et al., Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives,
European Journal of Medicinal Chemistry (2016), http://dx.doi.org/10.1016/j.ejmech.2016.10.065