Synthesis and structure-activity relationships of novel lincomycin derivatives. Part 4: Synthesis of novel lincomycin analogs modified at the 6- and 7-positions and their potent antibacterial activities

Article abstract of DOI:10.1038/ja.2017.54

To modify lincomycin (LCM) at the C-6 and the C-7 positions, we firstly prepared various substituted proline intermediates (7, 11-15 and 17). These proline intermediates were coupled with methyl 1-thio-α-lincosamide and tetrakis-O-trimethylsilylation followed by selective deprotection of the TMS group at the 7-position gave a wide variety of key intermediates (23-27, 47 and 50). Then, we synthesized a variety of novel LCM analogs modified at the 7-position in application of the Mitsunobu reaction, an S N 2 reaction, and a Pd-catalyzed cross-coupling reaction. Compounds 34 and 35 (1′-NH derivatives) exhibited enhanced antibacterial activities against resistant pathogens with erm gene compared with the corresponding 1′-N-methyl derivatives (3 and 37). On the basis of reported SAR, we modified the 4′-position of LCM derivatives possessing a 5-(2-nitrophenyl)-1,3,4-thiadiazol-2-yl group at the C-7 position. Compound 56 showed significantly potent antibacterial activities against S. pneumoniae and S. pyogenes with erm gene, and its activities against S. pneumoniae with erm gene were improved compared with those of 34 and 57. Although we synthesized novel analogs by transformation of a C-7 substituent focusing on the 1′-demethyl framework to prepare very potent analogs 73 and 75, it was impossible to generate novel derivatives exhibiting stronger antibacterial activities against S. pneumoniae with erm gene compared with 56.

Full text of DOI:10.1038/ja.2017.54

The Journal of Antibiotics (2017), 1–19
2017 Japan Antibiotics Research Association All rights reserved 0021-8820/17
www.nature.com/ja
&
ORIGINAL ARTICLE
Synthesis and structure–activity relationships of novel
lincomycin derivatives. Part 4: synthesis of novel
lincomycin analogs modified at the 6- and 7-positions
and their potent antibacterial activities
Yoshinari Wakiyama, Ko Kumura, Eijiro Umemura, Kazutaka Ueda, Takashi Watanabe, Keiko Yamada,
Takafumi Okutomi and Keiichi Ajito
To modify lincomycin (LCM) at the C-6 and the C-7 positions, we firstly prepared various substituted proline intermediates
(7, 11–15 and 17). These proline intermediates were coupled with methyl 1-thio-α-lincosamide and tetrakis-O-trimethylsilylation
followed by selective deprotection of the TMS group at the 7-position gave a wide variety of key intermediates (23–27, 47 and
50). Then, we synthesized a variety of novel LCM analogs modified at the 7-position in application of the Mitsunobu reaction,
an SN2 reaction, and a Pd-catalyzed cross-coupling reaction. Compounds 34 and 35 (1′-NH derivatives) exhibited enhanced
antibacterial activities against resistant pathogens with erm gene compared with the corresponding 1′-N-methyl derivatives
(3 and 37). On the basis of reported SAR, we modified the 4′-position of LCM derivatives possessing a 5-(2-nitrophenyl)-1,3,4-
thiadiazol-2-yl group at the C-7 position. Compound 56 showed significantly potent antibacterial activities against S.
pneumoniae and S. pyogenes with erm gene, and its activities against S. pneumoniae with erm gene were improved compared
with those of 34 and 57. Although we synthesized novel analogs by transformation of a C-7 substituent focusing on the
1′-demethyl framework to prepare very potent analogs 73 and 75, it was impossible to generate novel derivatives exhibiting
stronger antibacterial activities against S. pneumoniae with erm gene compared with 56.
The Journal of Antibiotics advance online publication, 31 May 2017; doi:10.1038/ja.2017.54
INTRODUCTION
(3) suppression19 of toxin production by Streptococcal strains and
(4) expected reasonable production cost of LCM/CLDM derivatives.
Thus, LCM derivatives might be more clinically valuable than
macrolide antibiotics, if they are effective against pathogens with
erm gene.
Macrolide antibiotics have been used in the clinical site for bacterial
respiratory infections so far. Recently, macrolide-resistant bacteria
with erm gene have markedly increased.1–3 Clarithromycin (CAM)4
and azithromycin5,6 are not effective enough against resistant patho-
gens such as Streptococcus pneumoniae and Streptococcus pyogenes with
Chemical modifications at the C-7 position of LCM were achieved
erm gene (Figure 1 and Table 1). Telithromycin (TEL)7 is effective by several research groups.17,18,20–32 None of them, however, showed
enough against S. pneumoniae with erm gene, but has the potential to effective antibacterial activities against resistant bacteria with erm
cause a serious liver damage8,9 and loss of consciousness.10,11 Thus, gene. On the other hand, we reported 7(S)-thiolincomycin analogs
TEL has scarcely been used in Japan. Novel azalides reported by Miura exhibiting antibacterial activities against resistant pathogens with erm
et al.12,13 are also effective against resistant pathogens, but these gene as the first example33–36 as far as we know. We recently reported
analogs are still under research process and have not been developed 7(S)-thiolincomycin analogs, such as compounds 1–3 (Table 1), as the
yet. Currently available oral antibiotics are not effective enough against first-generation derivatives in our research.37 Those compounds
resistant bacteria with erm and mef genes causing respiratory infections possessed weak antibacterial activities against resistant S. pneumoniae
and have some problems in safety or taste in clinical site.
with erm and mef genes, but compound 3 exhibited clearly improved
activities compared with clarithromycin, azithromycin, LCM and
CLDM as shown in Table 1. Recently, we also reported 7-S-substituted
novel LCM derivatives,38–41 and some of them showed stronger
activities than compound 3 did.
Lincomycin (LCM)14–17 and clindamycin (CLDM)18 are effective
against pathogens with mef gene in clinical isolates, but they are not
effective against resistant pathogens with erm gene (Figure 1 and
Table 1). As an overview, CLDM exhibits the following positive
characters: (1) availability in per os and intravenous administrations
Chemical modification of a proline moiety at the C-6 position of
(switch therapy is possible), (2) good distributions to tissue and cells, LCM and CLDM was performed by several research groups.17,24,42–48
Pharmaceutical Research Center, Meiji Seika Pharma, Yokohama, Japan
Correspondence: Dr K Ajito, Pharmaceutical Research Center, Meiji Seika Pharma, 760 Morooka-cho, Kohoku-ku, Yokohama 222-8567, Japan.
E-mail: keiichi.ajito@meiji.com
Received 18 January 2017; accepted 20 March 2017

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
2
N
N
Me
N
Me
Me
Me
O
O Me
R2
R1
O
N
Me
HO
Me
Me
N
HN
H
HO
O
N
OMe
Me
HO
OH
Me
O
R3
OH
OH
Me
Me
Me
Me
OMe
NMe2
Me
NMe2
Me
Me
SMe
Me
HO
HO
O
O
O
O
O
Me
Me
HO
OH
NMe2
Me
O
Me
O
O
O
O
O
O
OMe
Me
OMe
Me
HO
O
Me
Me
O
Lincomycin (LCM): R1 = OH, R2 = H, R3 = Me
1'-Demethyllincomycin:
1 = OH, R2 = H, R3 = H
Me
Me
OH
Me
Me
OH
O
O
O
O
R
Clindamycin (CLDM): R1 = H, R2 = Cl, R3 = Me
1'-Demethylclindamycin: R1 = H, R2 = Cl, R3 = H
Me
Telithromycin (TEL)
Clarithromycin (CAM)
Azithromycin (AZM)
Me
R2
R
4'
4'
4'
O Me
O Me
O Me
2'
2'
2'
OH
7
Cl
O
Me
7
7
1'
1'
N
1'
N
HN
H
N
HN
H
HN
H
R1
R1
Me
O
O
HO
SMe
HO
SMe
HO
SMe
HO
OH
HO
OH
HO
OH
4'-Substituted lincomycins: R = H, Me to noctyl
4'-Depropyl-4'-ethoxylincomycin: R = ethoxy
4'-Depropyl-4'-ethoxycarbonylmethyllincomycin:
R = ethoxycarbonylmethyl
4'-Depropyl-4'-npentylclindamycin:
1 = Me, R2 npentyl
1'-Demethyl-4'-depropyl-4'-npentylclindamycin:
R1 = H, R2 npentyl
VIC105403: R1 = H
VIC105404: R1 = 2-hydroxyethyl
VIC105405: R1 = 2-(R)-hydroxypropyl
VIC105446: R1 = 2-(S)-hydroxypropyl
R
=
=
4'-Depropyl-4'-p-toluenesulfonyloxylincomycin:
R = p-toluensulfonyloxy
Figure 1 Chemical structures of clarithromycin, azithromycin, telithromycin, lincomycin, clindamycin and a variety of reported analogs of lincomycin or
clindamycin.
Table 1 Anti-bacterial activities (MIC, μg ml− 1) of CAM, AZM, LCM, CLDM, and previously reported LCM derivatives (1–3)
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
3
R1
R1
On the other hand, Vicuron, which was consolidated by Pfizer,
reported the following compounds. VIC 105403 (Figure 1),24
possessing 1′-demethyl, 4′-n-pentyl and 7-methyl group, had
potent activities compared with CLDM. VIC 105404,24 possessing
1′-N-(2-hydroxyethyl), 4′-n-pentyl and 7-methyl group, was already
reported to have potent antibacterial activities as VIC 105403.
However, those did not show antibacterial activities against resistant
pathogens with erm gene. Furthermore, VIC 105405 and VIC
105446,24 having a branched side chain at the 1′-position, showed
less antibacterial activities than CLDM. Other VIC compounds
possessing a branched side chain, a 3-(pyridin-4-yl)propyl or an
n-butylthio group at the 4′-position, were already synthesized, but
their antibacterial activities were not disclosed in their patent.46
According to X-ray crystallographic analysis by Yonath et al.,47 we
hypothesized that CLDM had enough three-dimensional space around
the 1′-position and it might be able to enhance the antibacterial
activities by filling the corresponding space with other functional groups
except the Me group. On the basis of the above hypothesis, we designed
and synthesized novel 7(S)-substituted LCM derivatives modified at the
1′- and/or 4′-position(s) at the proline moiety. Anti-bacterial activities
of these novel compounds are also disclosed in this report.
O
O
a or b
N
N
OBn
OH
Boc
Boc
7: R1 = nPr
13: R1 = iBu
14: R1 = nPentyl
15: R1 =
4: R1 = allyl
5: R1 =
Me
Me
6: R1 =
Me
4
c
R2O
d or e
O
HO
O
N
OBn
Boc
N
OBn
9: R2 = TBS
10: R2 = Me
Boc
8
a
R1
R1
R2O
O
O
OR2
N
N
OH
Boc
Boc
RESULTS AND DISCUSSION
Synthesis of proline derivatives
16: R1 = allyl; R2 = Bn
17: R1 = nPr; R2 = H
11: R2 = TBS
12: R2 = Me
a
Synthesis of proline derivatives is shown in Scheme 1. Synthetic route for
modification of the proline moiety at the 4′-position was already
reported by Pedregal et al.48,49 We firstly prepared starting materials
(4–6 and 16), and compound 8 was synthesized by hydroboration of
4 followed by treatment with tert-butyldimethylsilyl chloride (TBSCl) or
methyl iodide under the basic condition to give compounds 9 and 10.
The compounds 4–6, 9, 10 and 16 were reduced with H2 in the presence
of Pd/C to give the corresponding carboxylic acids (7, 11–14 and 17),
Scheme 1 Synthesis of proline derivatives. Conditions: (a) H2, Pd/C, MeOH,
r.t., 0.5–4.5 h; (b) 1 N NaOH, MeOH, r.t., 22 h; (c) (1) 9-BBN, THF, 50 °C,
1 h, (2) 1 N NaOH, 35% H2O2, 0 °C, 2 h; (d) TBSCl, imidazole, DMF, r.t.,
30 min; (e) MeI, NaH, DMF, r.t., 30 min. 9-BBN, 9-borabicyclo[3.3.1]
nonane; DMF, dimethylformamide; Mel, methyl iodide; TBSCl, tert-
butyldimethylsilyl chloride; r.t., room temperature; THF, tetrahydrofuran.
1
respectively. Compound 15 was prepared by hydrolysis of 6. H NMR
This portion has the following features: (1) Regarding configuration spectra of compounds 7, 8, 10, 13–15 and 17 were observed as two sets
of signals because of a rotamer by the tert-butoxycarbonyl (Boc) group.
between the 2′- and 4′-positions of a proline ring, an analog with trans
configuration exhibited more potent antibacterial activity compared
with one with cis configuration. (2) 4′-Depropyl-3′-propyllincomycin
has not been synthesized, but 4′-depropyl-5′-propyllincomycin has
already been synthesized. Its antibacterial activity was weaker than that
of LCM. (3) 1′-Demethylclindamycin (Figure 1) was two times as
active in vitro against Sarcina lutea as CLDM, but 1′-demethyllinco-
mycin was about one-twentieth as active as LCM (relative potency
against S. lutea: 1′-demethylclindamycin4CLDM4LCM41′-
Synthesis of key intermediates 23–27 and transformation of 23 and 36
Synthesis of key intermediates 23–27 and transformations of 23 and 36
are shown in Scheme 2. Compounds 18–22 were synthesized by
condensation of compounds 7 and 12–15 with methyl 1-thio-α-
lincosamide (MTL), respectively. Tetra-O-trimethylsiliylation of all hydro-
xyl groups and successive regioselective deprotection of the TMS group at
the 7-position gave key intermediates (23–27). Furthermore, novel LCM
derivatives 32–35 were synthesized via two or three steps from compound
23 by the Mitsunobu reaction at the 7-position and deprotection of the
TMS groups and the Boc group at the 1′-position. On the other hand, 1′-
N-methyl analog 37 was prepared from 36 following the similar
demethyllincomycin= 8444140.05).21,42–43
1′-Demethyl-1′-N-
ethyllincomycin possessed the same activity as LCM. (4) Regarding
SAR of a chain length (H, Me to n-octyl) at the 4′-position of the
proline moiety for LCM (Figure 1), the in vitro antibacterial activities
were enhanced until reaching a maximum at the hexyl analog.21,44
A similar in vivo activity was indicated, but maximum effect was
exhibited by an n-pentyl group. Furthermore, alternative in vitro SAR
were observed by changing a chain length (Figure 1) for a 4′-alkyl-
substituent of CLDM and a 4′-alkyl-substituent of 1′-demethylclinda-
mycin (relative potency: 4′-depropyl-4′-n-pentylclindamycin4CLDM,
1′-demethyl-4′-depropyl-4′-n-pentylclindamycin41′-demethylclinda-
mycin).21 However, antibacterial activities of those compounds against
resistant pathogens with erm gene were not disclosed.
(5) 4′-Depropyl-4′-ethoxylincomycin had only ~ 2% antibacterial
activities of LCM, and 4′-depropyl-4′-ethoxycarbonylmethyllincomy-
cin and 4′-depropyl-4′-p-toluenesulfonyloxylincomycin were essen-
tially inactive in antibacterial testing.17,21,45
1
procedure as the above. H NMR spectra of compounds 18–20 and 23
were observed as two sets of signals because of a rotamer by the Boc
1
group and compounds 25–27 showed broad peaks in H NMR spectra.
Compounds 32–35 whose Boc groups were deprotected, however,
1
showed a single set of signals and sharp peaks in H NMR spectra.
Synthesis of 1′-N-modified novel LCM derivatives possessing a
substituted 1,3,4-thiadiazol-2-ylthio group at the 7-position
Synthesis of 1′-N-modified novel LCM derivatives possessing
the substituted 1,3,4-thiadiazol-2-ylthio group at the 7-position is
shown in Scheme 3. Desired 1′-N-modified derivatives 38, 39, 41 and
45 were prepared from 34 or 35 by reductive aminoalkylation.
Consequently, the TBS groups of 39 and 41 were removed by TBAF
to give compounds 40 and 42, respectively. Compound 43 was
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
4
R1
R1
4'
O Me
7
O Me
R1
OH
O
OH
O
O
N
N1'
HN
HN
a
b, c
Boc
Boc
H
H
N
OH
Me
7
Boc
TMSO
SMe
HO
SMe
OH
O
7: R1
12: R1 = MeO
13: R1 = iBu
14: R1
15: R1
=
nPr
6
H2N
HO
TMSO
nPr
OTMS
HO
OH
H
23: R1
=
18: R1
=
nPr
SMe
24: R1 = MeO
25: R1 = iBu
19: R1 = MeO
20: R1 = iBu
=
=
npentyl
HO
OH
Me
26: R1
=
npentyl
27: R1 = Me
21: R1
22: R1
=
=
npentyl
MTL
Me
N
S
N
N
nPr
nPr
4'
O Me
7
O Me
NHR
S
NH2
SR
SR
O
N
N
HN
6
HN
H 1'
R:
SMe
e, g
29: R = Boc; 33: R = H
d
28, 32
Boc
23
H
HO
O
H
N
N
TMSO
SMe
N
N
NO2
N
S
S
HO
OH
N
TMSO
OTMS
S
28-30
31 (isolated)
32-34
35
f
MeHN
30, 34
31, 35
N
S
N
nPr
nPr
O Me
O Me
S
NHMe
OH
O
S
N
HN
N
HN
H
HO
h, i
Me
TMSO
Me
H
O
SMe
SMe
TMSO
OTMS
HO
OH
36
37
Scheme 2 Synthesis of key intermediates 23–27 and transformation of 23 and 36. Conditions: (a) MTL, DCC, HOBt, DMF, r.t., 3–23 h; (b) TMSCl, HMDS,
Py, r.t., 1–7 h; (c) 6 N AcOH, MeOH, r.t., 0.5–11 h; (d) DEAD, PPh3, HSR (the corresponding heteroaromatic thiols), THF, 0 °C to r.t., 3–18 h; (e) 1 N HCl,
MeOH, r.t., 0.5–2.5 h; (f) 4 N HCl-EtOAc, MeOH, 0 °C to r.t., 4.5 h; (g) 4 N HCl-EtOAc, MeOH, r.t., 2–2.5 h; (h) DEAD, PPh3, 5-(5-(methylamino)thiazol-4-
yl)-1,3,4-thiadiazole-2-thiol, THF, r.t., 2 h, (i) 1 N HCl, MeOH, r.t., 1 h. DCC, dicyclohexylcarbodiimide; DEAD, diethyl azodicarboxylate; DMF,
dimethylformamide; HMDS, hexamethyldisilazane; HOBt, 1-hydroxybenzotriazol; MTL, methyl 1-thio-α-lincosamide; PPh3, triphenylphosphine; Py, pyridine;
THF, tetrahydrofuran; TBSCl, tert-butyldimethylsilyl chloride; r.t., room temperature.
synthesized in application of (R)-2-methyloxirane under the basic intermediates 51 and 52 partially included impurity that was not
condition from 35. Compound 44 was also prepared by acetic removed by purification steps.
anhydride from 35.
Synthesis of novel LCM derivatives with a variety of 4′-substituents
Synthesis of novel LCM derivatives 48 and 53 possessing a germinal possessing the substituted 1,3,4-thiadiazol-2-yl-thio group at the
bis-propyl moiety or a 3-(dimethylamino)propyl group at the
7-position
4′-position
Synthesis of novel LCM derivatives having a 3-methoxypropyl, an
Synthesis of novel LCM derivatives 48 and 53 possessing a germinal i-butyl or an n-pentyl group at the 4′-position, whose 7-position was
bis-propyl moiety and a 3-(dimethylamino)propyl group, respectively, the substituted 1,3,4-thiadiazol-2-yl-thio group, is shown in Scheme 5.
at the 4′-position, and having the 5-(2-nitrophenyl)-1,3,4-thiadiazol- Compounds 54–56 and 58 were prepared from key intermediates
2-ylthio group at the 7-position, is shown in Scheme 4. Key 24–26 by the similar procedure to compound 48. Reductive aminoalk-
intermediates 47 and 50 were, respectively, synthesized in the ylation of 56 and 58 afforded the desired compounds 57 and 59,
application of condensation, tetrakis-O-trimethylsilylation, and selec- respectively.
tive deprotection with the similar procedure to compound 23. Later, a
7-S-substituent was introduced to 47 by the Mitsunobu reaction, and Synthesis of proline-modified novel LCM derivatives possessing a
deprotection gave a desired derivative 48. Compound 50 was (4-morpholinocarbonyl)phenylthio group at the 7-position
transformed to 51 by the Mitsunobu reaction and desilylation. Then, Synthesis of proline-modified novel LCM derivatives possessing a
compound 51 was reacted with sodium azide, and an azide group was (4-morpholinocarbonyl)phenylthio group at the 7-position is shown
reduced to an amino group with triphenylphosphine-water. The in Scheme 6. Because LCM derivatives possessing a (4-morpholino-
afforded amino group in 52 was applied with reductive aminoalkyla- carbonyl)phenylthio group at the 7-position exhibited improved
tion followed by deprotection of the Boc group under the acidic antibacterial activities, we designed compounds 67–69. We already
condition with trifluoroacetic acid (TFA) to give the desired novel reported the methanesulfonyl (Ms) route37,38 to introduce a phenyl
1
derivative 53. H NMR spectra of compounds 47 and 50 were also group via sulfur atom at the 7-position. The Ms route was applied to
observed as broad peaks by the influence of a Boc group. Although the compounds 23 and 27 to give intermediates 60 and 61, respectively.
final product 53 could be purified as a single molecule, both 1H NMR spectra of compounds 60–62 were observed as two sets of
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
5
NO2
N
N
N
N
N
S
S
N
N
N
nPr
nPr
nPr
O
HN
HO
Me
7
S
O
HN
HO
Me
7
O
Me
7
S
S
NHMe
NHMe
S
S
S
N1'
R
N
1'
N
HN
H
HO
a or b
1'
b or d or e
f
R
34
H
O
H
O
35
O
S
N
SMe
SMe
SMe
Me
HO
38: R = iPr
OH
HO
OH
HO
OH
45
41: R = CH2CH2OTBS
42: R = CH2CH2OH
43: R = (R)-propan-2-ol
44: R = Ac
c
39: R = CH2CH2OTBS
40: R = CH2CH2OH
c
Scheme 3 Synthesis of 1′-N-modified novel LCM derivatives possessing the substituted 1,3,4-thiadiazol-2-ylthio group at the 7-position. Conditions:
(a) acetone, NaBH(OAc)3, AcOH, ClCH2CH2Cl, 0 °C to r.t., 15 h; (b) 2-(tert-butyldimethylsilyloxy)acetaldehyde, NaBH(OAc)3, AcOH, ClCH2CH2Cl, 0 °C to r.t.,
15 h for 39, r.t., 15 h for 41; (c) TBAF, THF, 0 °C to r.t., 15 h for 40, 5 h for 42; (d) (R)-2-methyloxirane, i-Pr2NEt, MeOH, 0 °C, 16 h;
(e) Ac2O, MeOH, 0 °C, 1.5 h; (f) 4-methylthiazole-5-carbaldehyde, NaBH(OAc)3, AcOH, MeOH, r.t., 15 h. LCM, lincomycin; TBAF, tetra-n-butylammonium
fluoride; THF, tetrahydrofuran; r.t., room temperature.
NO2
N
N
nPr
nPr
nPr
nPr
nPr
nPr
O Me
O Me
O Me
S
OH
O
OH
O
S
N
N
a
d, e
N
H
HN
H
HO
HN
b, c
HN
H
HO
Boc
Boc
TMSO
17
H
O
SMe
SMe
SMe
HO
OH
TMSO
OTMS
HO
OH
46
47
48
NO2
N
N
O Me
O Me
O Me
S
TBSO
b, c
TBSO
a
HO
d, f
OH
OH
O
S
N
N
HN
H
N
HN
H
HN
H
Boc
Boc
Boc
O
11
O
TMSO
SMe
HO
SMe
HO
SMe
TMSO
OTMS
HO
OH
HO
OH
51
49
50
NO2
NO2
N
N
N
S
N
S
O Me
O Me
HN
Me2N
S
S
H2N
N
HN
HO
N
i, e
H
g, h
Boc
H
O
H
O
SMe
HO
SMe
HO
OH
HO
OH
53
52
Scheme 4 Synthesis of 48 and 53. Conditions: (a) MTL, DCC, HOBt, DMF, r.t., 14 h; (b) TMSCl, HMDS, Py, r.t., 1 h from 46, 20 min from 49; (c) 6 N
AcOH, MeOH, r.t., 1–1.5 h; (d) 5-(2-nitrophenyl)-1,3,4-thiadiazole-2-thiol, DEAD, PPh3, THF, 0 °C to r.t., 6–10 h; (e) TFA, 0 °C to r.t., 30 min;
(f) TBAF, AcOH, THF, r.t., 5 h; (g) NaN3, CBr4, PPh3, DMF, r.t. to 50 °C, 2 h; (h) PPh3, H2O, THF, r.t. to 50 °C, 3 h; (i) HCHO, NaBH(OAc)3, AcOH, MeOH,
r.t., 20 min. DCC, dicyclohexylcarbodiimide; DEAD, diethyl azodicarboxylate; DMF, dimethylformamide; HMDS, hexamethyldisilazane; HOBt,
1-hydroxybenzotriazol; MTL, methyl 1-thio-α-lincosamide; PPh3, triphenylphosphine; Py, pyridine; TBAF, tetra-n-butylammonium fluoride; TFA, trifluoroacetic
acid; THF, tetrahydrofuran; r.t., room temperature.
signals because of a rotamer by the Boc group. The desired analogs 67 steps from 23, and precursors 72 and 74 were synthesized by
and 68 were prepared from 60 and 62, respectively, by (i) hydrolysis Pd-catalyzed cross-coupling reaction of 7140,50 with the corresponding
under the basic condition, (ii) condensation with morpholine and (iii) bromides. Deprotection of the Boc group afforded the desired analogs
1
deprotection of the Boc group with TFA. Compound 69 was 73 and 75. H NMR spectra of compounds 72 and 74 were observed
synthesized from 68 by reductive aminoalkylation with HCHO and as two sets of signals because of a rotamer by the Boc group, but both
NaBH(OAc)3 in an acidic condition by AcOH.
of the final compounds 73 and 75 showed a single set and sharp peaks
in NMR spectra.
Synthesis of 73 and 75
Synthesis of novel LCM derivatives 73 and 75 is shown in Scheme 7. SAR analysis of 7-S-substituted 1′-NH LCM derivatives (32–35) and
We have already reported a Pd-catalyzed cross-coupling route to 1′-N-Me analog 37
introduce an aryl group at the 7-position of 7(S)-7-deoxy-7- Antibacterial activity of LCM was reduced by 1′-N-demethylation, but
mercaptlincomycin.40 A key intermediate 71 was prepared via four that of CLDM was enhanced by 1′-N-demethylation. Thus, we were
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
6
R1
R1
Me
O Me
O Me
O Me
OH
SR
O
SR
O
N
N
H
N
HN
H
TMSO
HN
HO
HN
H
HO
c
a, b
Boc
Me
H
56, 58
O
SMe
SMe
SMe
OH
NO2
TMSO
OTMS
HO
OH
HO
N
N
N
N
N
N
NO2
24: R1
=
54: R1
=
MeO
MeO
25: R1 = iBu
55: R1 = iBu
R
R
57: R
59: R
S
S
26: R1
=
nPentyl
56: R1
=
nPentyl
N
N
S
N
S
N
S
58: R1
=
nPentyl
S
MeHN
MeHN
Scheme 5 Synthesis of novel LCM derivatives with
a variety of 4′-substituents possessing the substituted 1,3,4-thiadiazol-2-yl-thio group at the
7-position. Conditions: (a) DEAD, PPh3, HSR, THF, 0 °C to r.t., 9.5–24 h; (b) TFA, 0 °C to r.t., 15–90 min; (c) HCHO, NaBH(OAc)3, AcOH, MeOH, r.t., 1 h.
DEAD, diethyl azodicarboxylate; LCM, lincomycin; TFA, trifluoroacetic acid; THF, tetrahydrofuran; r.t., room temperature.
CO2Me
CO2H
R1
R1
R1
O Me
O Me
O Me
OH
O
S
S
N
N
N
HN
H
HN
H
HN
H
f
e
a, b, c
Boc
Boc
Boc
O
O
TMSO
SMe
HO
SMe
HO
SMe
TMSO
OTMS
HO
OH
HO
OH
63: R1
64: R1
=
=
nPr
nPentyl
23: R1
27: R1
=
=
nPr
Me
60: R1
=
=
=
nPr
Me
nPentyl
61: R1
d
62: R1
O
O
O
N
O
N
O
N
O
R1
R1
Me
h
O Me
O Me
O Me
S
S
S
N
HN
H
N
H
N
HN
H
HN
H
g
Boc
Me
O
O
O
HO
SMe
HO
SMe
HO
SMe
HO
OH
HO
OH
nPr
nPentyl
HO
OH
65: R1
66: R1
=
=
nPr
nPentyl
67: R1
68: R1
=
=
69
Scheme 6 Synthesis of proline-modified novel LCM derivatives possessing a (4-morpholinocarbonyl)phenylthio group at the 7-position. Conditions: (a) MsCl,
NEt3, CHCl3, r.t., 30 min; (b) methyl 4-mercaptobenzoate, K2CO3, DMF, 80–100 °C, 1–6 h; (c) 1 N HCl, MeOH, r.t., 20 min; (d) H2, Pd/C, MeOH, r.t.,15 h;
(e) 1 N NaOH, MeOH, r.t., 1–7 days; (f) morpholine, WSC, HOBt, DMF, r.t. 22–62 h, (g) TFA, À15 to 0 °C, 40 min and (h) HCHO, AcOH, NaBH(OAc)3,
MeOH, 30 min. DMF, dimethylformamide; HOBt, 1-hydroxybenzotriazol; LCM, lincomycin; r.t., room temperature; TFA, trifluoroacetic acid; WSC, water-
soluble carbodiimide.
interested in the potency of 1′-N-demethyl products of 7(S)-sub- SAR analysis of antibacterial activities (MIC, μg ml− 1) of 7-S-
stituted LCM derivatives 1–3 as shown in Table 1. Thus, we substituted 1′-N-modified LCM derivatives (38, 40 and 42–45)
synthesized 1′-demethyl analogs of 1–3 (32–34) and compounds 35 For the purpose of accumulating detail information of SAR at the
and 37 possessing an alternative 7-substituent. Antibacterial activities 1′-position, we synthesized novel LCM derivatives possessing various
of those are shown in Table 2. Among them, 1′-NH derivatives 32, 34 substituents at the 1′-position. At this point, the 5-(2-nitrophenyl)-
and 35 exhibited improved antibacterial activities against S. pneumo- 1,3,4-thiadiazol-2-yl group and the 4-(5-methylamino-thiazole-4-yl)-
niae with erm gene compared with the corresponding 1,3,4-thiadiazol-2-yl group were selected as a 7-substituent because of
1′-N-methyl analogs (1,3 and 37), respectively. Because 34 and 35 their SAR analysis (Tables 1 and 2). Consequently, compounds 40 and
especially showed enhanced antibacterial activities against the target 42, possessing a 2-hydroxyethyl group at the 1′-position, showed anti-
pathogens, we found that double modifications at the C-6 and C-7 bacterial activities against target pathogens as shown in Table 3, but we
positions were important to improve antibacterial activities against concluded that it was difficult to enhance antibacterial activities
S. pneumoniae with erm gene.
against S. pneumoniae with erm gene by introducing an alternative
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
7
nPr
nPr
d
group and a 4-(pyrimidin-5-yl)phenyl group, respectively, exhibited
markedly potent antibacterial activities against S. pneumoniae with erm
gene. We confirmed that combination modification at the C-6
position (the proline moiety) and the C-7 position was important to
enhance antibacterial activities against S. pneumoniae and S. pyogenes
with erm gene.
O
HN
HO
Me
O
HN
HO
Me
SAc
O
SH
O
N
N
a, b, c
Boc
Boc
H
H
23
SMe
SMe
HO
70
OH
HO
OH
71
CONCLUSION
nPr
nPr
f
To modify both the C-6 position (the proline moiety) and the C-7
position of LCM, we firstly prepared various substituted proline
intermediates. The intermediates were coupled with MTL to give a
wide variety of 1′-N-Boc-1′-demethyllincomycin derivatives. The 7-S-
substituents were introduced as follows. Key intermediates 23–26, 36,
47 and 50 were synthesized by the Mitsunobu reaction37,38 with the
corresponding thiol. Other key intermediates 23 and 27 were
transformed to 7-S-benzoate by an SN2 reaction37,38 via Ms deriva-
O
HN
HO
Me
O
Me
SR
O
SR
O
N
N
H
HN
H
HO
e
Boc
H
SMe
SMe
HO
72, 74
OH
HO
OH
73, 75
N
72, 73: R =
74, 75: R =
tives, and the benzoate moiety was finally converted to
a
4-(morpholinocarbonyl)phenyl moiety (Scheme 6). 7(S)-7-Deoxy-7-
thiolincomycin (71) was coupled with biaryl bromide under the
Pd-catalyzed cross-coupling reaction (Scheme 7).40,50 Compounds 38,
40 and 42–45 were also prepared from 34 or 35. Those methodologies
were found to be very practical to synthesize various LCM analogs
modified at the C-6 and -7 positions.
N
N
Scheme 7 Synthesis of 73 and 75. Conditions: (a) MsCl, NEt3, CH2Cl2, 0 °
C, 1 h; (b) AcSK, DMF, 60 °C, 10 h; (c) 1 N HCl, MeOH, r.t., 1 h;
(d) NaOMe, MeOH, r.t., 1.5 h; (e) 3-(4-bromophenyl)pyridine or 5-(4-
bromophenyl)pyrimidine,
Pd2(DBA)3,
Xantphos,
i-Pr2NEt,
dioxane,
By SAR analysis of combination modification at the 1′- and
7-position, we concluded that it was difficult to enhance anti-
bacterial activities against S. pneumoniae with erm gene by introducing
an alternative substituent at the 1′-position, except a hydrogen atom or
a methyl group. Then, we selected a hydrogen atom and a methyl
group at the 1′-position for further modification of the proline moiety.
We next modified the 4′-position (in the proline moiety) of LCM
derivatives possessing a 5-(2-nitrophenyl)-1,3,4-thiadiazol-2-yl group
or a 4-(5-methylamino-thiazol-4-yl)-1,3,4-thiadiazol-2-yl group at the
C-7 position (Table 4). Compounds 56 and 57, possessing an n-pentyl
group instead of an n-propyl group at the 4′-position, exhibited strong
antibacterial activities against resistant bacteria with erm gene.
Although antibacterial activities of TEL against S. pneumoniae with
erm gene were stronger than those of 56, antibacterial activities of 56
against S. pyogenes with erm gene and resistant bacteria with mef gene
were remarkably stronger than those of TEL. We found that
combination modification at the C-6 position (the proline moiety)
and the C-7 position was quite important to enhance antibacterial
activities against S. pneumoniae and S. pyogenes with erm gene. The
above SAR might be partially related to the polarity or water solubility
of a molecule, but we only have limited SAR information. Further
combination modification at the C-6 and C-7 positions of LCM
analogs is in progress.
reflux, 5–6 h; (f) TFA, CH2Cl2, − 20 °C to r.t., 3–5.5 h. DMF,
dimethylformamide; r.t., room temperature; TFA, trifluoroacetic acid;
Xantphos,
4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, Pd2(DBA)3,
tris(dibenzylideneacetone)dipalladium(0).
substituent at the 1′-position, except a hydrogen atom or a methyl
group. These results were closely related to SAR of 1′-N-alkyl-1′-
demethyllincomycin.17,21,24 Then, we selected a hydrogen atom and a
methyl group at the 1′-position for modification of the proline moiety.
SAR analysis of 7-S-substituted 1′-N- and 4′-modified LCM
derivatives (48 and 53–59) and TEL
To confirm whether 7-S-substituted LCM analogs show similar anti-
bacterial spectra to those reported previously, we synthesized
1′-demethyllincomycin derivatives possessing various substituents at
the 4′-position. Structures of 7-S-substituents followed those in
Table 3. As shown in Table 4, compounds 56 and 57, possessing an
n-pentyl group instead of an n-propyl group at the 4′-position,
exhibited strong antibacterial activities against resistant bacteria
with erm gene. Although antibacterial activities of TEL against
S. pneumoniae with erm gene were stronger than those of 56, anti-
bacterial activities of 56 against S. pyogenes with erm gene and resistant
bacteria with mef gene were remarkably stronger than those of TEL.
EXPERIMENTAL PROCEDURES
General methods
SAR analysis of 7-S-substituted 1′-N- and 4′-modified LCM
1H NMR spectra were measured with a BRUKER Ascend 400 NMR spectro-
meter (Bruker Corporation, Coventry, UK) for 400 MHz, JEOL JNM-GSX 400
NMR spectrometer (JEOL,Tokyo, Japan) for 400 MHz or a Varian Gemini 300
NMR spectrometer (Varian, Palo Alto, CA, USA) for 300 MHz in CDCl3 or
CD3OD. TMS (0 p.p.m.) in CDCl3 or CD3OD was used as an internal reference
standard. Mass spectra (MS) were obtained on a JEOL JMS-700 mass
spectrometer (JEOL) or Agilent Technologies 6530-Q-TOF LC/MS mass
spectrometer (Agilent Technologies, Santa Clara, CA, USA). The optical
rotations were recorded with Jasco P-2300 digital polarimeter (Jasco Corpora-
tion, Tokyo, Japan). Column chromatography was performed with silica gel
(Wakogel C200; Wako Pure Chemical Industries, Osaka, Japan). Preparative
thin layer chromatography was performed with silica gel (Merck, Darmstadt,
derivatives with an alternative 7-S-substituent (67–69, 73 and 75)
We have reported significant potent antibacterial activities of LCM
derivatives possessing a substituted phenyl group at the C-7 position
so far.40 This time, we transformed the proline moiety (the 1′-and 4′-
position) of 7-S-substituted phenyl derivatives as shown in Table 5,
such as 7(S)-7-{4-(morphorinocarbonyl)phenylthio}lincomycin (76),
7(S)-7-{4-(pyridin-3-yl)phenylthio}lincomycin (77) and 7(S)-7-{4-
(pyrimidin-5-yl)phenylthio}lincomycin (78). Their antibacterial
activities are shown in Table 5. The n-pentyl analogs 68 and 69 could
not exhibit improved antibacterial activities against S. pneumoniae and
S. pyogenes with erm gene compared with 56 and 57. On the other
hand, 1′-NH LCM derivatives 73 and 75 with a 4-(pyridin-3-yl)phenyl Germany; TLC plates Silica gel 60 F254). All organic extracts were dried over
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
8
Table 2 Anti-bacterial activities (MIC, μg ml− 1) of 7-S-substituted 1′-NH LCM derivatives (32–35) and 1′-N-Me analog 37
anhydrous MgSO4, and the solvent was removed with a rotary evaporator (m, 1H), 3.57–3.83 (m, 3H), 4.25–4.50 (m, 1H), 4.96–5.32 (m, 2H) and
under reduced pressure.
7.27–7.47 (m, 5H).
(2S,4R)-1-N-(tert-butoxycarbonyl)-4-n-propylpyrrolidine-2-
carboxylic acid (7)
(2S,4R)-2-Benzyl 1-tert-butyl 4-(3-(tert-butyldimethylsilyloxy)
propyl)pyrrolidine-1,2-dicarboxylate (9)
To a solution of compound 4 (1.0 g, 2.89 mmol) in MeOH (10 ml) was added
Pd/C (100 mg), and then vigorously stirred in hydrogen atmosphere at room
temperature for 2 h. The mixture was filtrated with celite, and then the solution
was concentrated under reduced pressure. The resulting residue was filtrated
with Chromatodisc (0.45 μm) (Kurabo Industries, Osaka, Japan). The filtrated
solution was concentrated under reduced pressure to obtain the title compound
(745 mg, quant) as a colorless solid. FAB-MS m/z 258 (M+H)+ as C13H23NO4;
1H NMR (400 MHz, CD3OD) ) δ 0.70–0.93 (m, 3H), 1.10–1.41 (m, 13H),
1.65–1.87 (m, 1H), 1.93–2.06 (m, 1H), 2.10–2.27 (m, 1H), 2.73–2.89 (m, 1H),
3.43–3.63 (m, 1H) and 4.00–4.25 (m, 1H).
To a solution of compound 8 (2.80 g, 7.70 mmol) in dimethylformamide
(DMF) (15 ml) were added imidazole (1.05 g, 15.4 mmol) and TBSCl (1.74 g,
11.56 mmol), and then stirred at room temperature for 30 min. The mixture
was extracted with ethyl acetate and then the organic phase was dried over
Na2SO4, filtrated and concentrated under reduced pressure. The resulting
residue was pumped up to obtain the title compound (3.50 g, crude). The total
amount of this compound was used without purification to synthesize 11.
(2S,4R)-2-benzyl 1-tert-butyl 4-(3-methoxypropyl)pyrrolidine-1,2-
dicarboxylate (10)
To a solution of compound 8 (900 mg, 2.48 mmol) in DMF (9 ml) was added
55% NaH in oil (99.2 mg, 3.72 mmol) and stirred at room temperature for
30 min. To the mixture was added methyl iodide (924 μl, 14.86 mmol) and
then stirred at room temperature for 1 h. The solution was added to the
saturated aqueous NaCl. The desired compound was extracted with ethyl
acetate and then the organic phase was dried over Na2SO4, filtrated and
concentrated under reduced pressure. The resulting residue was purified by
silica gel column chromatography (hexane/ethyl acetate= 20/1 to 4/1) to obtain
the title compound (240 mg, 26%) as a colorless oil. ESI-MS m/z 378 (M+H)+
as C21H31NO5; 1H NMR (400 MHz, CDCl3) δ 1.33, 1.45 (s x 2, 9H), 1.35–1.50
(m, 2H), 1.50–1.57 (m, 2H), 1.75–1.91 (m, 1H), 2.03–2.13 (m, 1H), 2.18–2.33
(2S,4R)-2-benzyl 1-tert-butyl 4-(3-hydroxypropyl)pyrrolidine-1,2-
dicarboxylate (8)
To a solution of compound 4 (1.03 g, 2.98 mmol) in tetrahydrofuran (THF)
(3 ml) was added 0.5 M 9-BBN in THF solution (8.95 ml, 4.47 mmol) and
stirred at 50 °C for 1 h. Then, 1N NaOH (4 ml) and 35% H2O2 (4 ml) were
added to the mixture and stirred at 0 °C for 2 h. The solution was added to the
saturated aqueous NaCl. The desired compound was extracted with ethyl
acetate, and then the organic phase was dried over Na2SO4, filtrated and
concentrated under reduced pressure. The resulting residue was purified by
silica gel column chromatography (hexane/ethyl acetate= 3/1 to 1/2) to obtain
the title compound (937 mg, 87%) as a colorless solid. EI-MS m/z 363 (M)+ as
C20H29NO5; 1H NMR (400 MHz, CDCl3) δ 1.31–1.48 (m, 11H), 1.49–1.60 (m, 1H), 2.90–3.04 (m, 1H), 3.31 (s, 3H), 3.25–3.40 (m, 2H), 3.59–3.80
(m, 2H), 1.75–1.92 (m, 1H), 2.05–2.14 (m, 1H), 2.19–2.39 (m, 1H), 2.88–3.05 (m, 1H), 4.25–4.47 (m, 1H), 5.03–5.29 (m, 2H) and 7.29–7.42 (m, 5H).
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
9
Table 3 Anti-bacterial activities (MIC, μg ml− 1) of 7-S-substituted 1′-N-modified LCM derivatives (38, 40 and 42–45)
Me
OH
N
N
N
S
S
MeHN
(2S,4R)-1-N-(tert-butoxycarbonyl)-4-(3-(tert-butyldimethylsilyloxy)
(2S,4R)-1-N-(tert-butoxycarbonyl)-4-n-pentylpyrrolidine-2-
propyl)pyrrolidine-2-carboxylic acid (11)
carboxylic acid (14)
Compound 9 (3.50 g, crude) in MeOH (50 ml) were treated for 30 min Compound 6 (1.69 g, 4.53 mmol) in MeOH (20 ml) were treated for 2 h
according to the similar procedure as described for the preparation of 7 to
afford 14 (1.16 g, 89.5%) as a colorless solid. FAB-MS m/z 286 (M+H)+ as
C15H27NO4; 1H NMR (400 MHz, CD3OD) δ 0.80–0.98 (m, 3H), 1.20–1.51
(m, 8H), 1.42, 1.46 (s x 2, 9H), 1.78–1.98 (m, 1H), 2.10 (ddd, J = 12.7, 6.2,
2.1 Hz, 1H), 2.19–2.36 (m, 1H), 2.85–3.01 (m, 1H), 3.57–3.75 (m, 1H),
4.17–4.33 (m, 1H).
according to the similar procedure as described for the preparation of 7 to
afford 11 (3.02 g, crude). The total amount of this compound was used to
synthesize 49.
(2S,4R)-1-N-(tert-butoxycarbonyl)-4-(3-methoxypropyl)
pyrrolidine-2-carboxylic acid (12)
Compound 10 (200 mg, 0.530 mmol) in MeOH (2 ml) were treated for 1 h
according to the similar procedure as described for the preparation of 7 to
afford 12 (152 mg, crude). The total amount of this compound was used
without purification to synthesize 19.
(2S,4R)-1-N-(tert-butoxycarbonyl)-4-((E)-pent-2-enyl)pyrrolidine-2-
carboxylic acid (15)
To a solution of compound 6 (2.0 g, 5.79 mmol) in MeOH (20 ml) was added
1 M aqueous NaOH (20 ml) and stirred at room temperature for 22 h. The
mixture was diluted with H2O and Et2O and washed by Et2O. Aqueous layer
was added to the saturated aqueous citric acid, extracted with ethyl acetate and
then the organic phase was washed with H2O, dried over Na2SO4, filtrated and
concentrated under reduced pressure to obtain the title compound (1.55 g,
94.5%) as a colorless solid. FAB-MS m/z 284 (M+H)+ as C15H25NO4; 1H NMR
(400 MHz, CD3OD) δ 0.89–1.05 (m, 3H), 1.41 (s, 6H), 1.45 (s, 3H), 1.85–2.15
(m, 6H), 2.23–2.39 (m, 1H), 2.92–3.09 (m, 1H), 3.52–3.68 (m, 1H), 4.18–4.31
(m, 1H), 5.30–5.44 (m, 1H) and 5.46–5.60 (m, 1H).
(2S,4R)-1-N-(tert-butoxycarbonyl)-4-i-butylpyrrolidine-2-carboxylic
acid (13)
Compound 5 (195.3 mg, 0.54 mmol) in MeOH (2 ml) were treated for
30 min according to the similar procedure as described for the
preparation of 7 to afford 13 (141.1 mg, 96%) as an off-white solid.
ESI-MS m/z 272 (M+H)+ as C14H25NO4; 1H NMR (400 MHz, CD3OD) δ
0.90 (d, J = 6.7 Hz, 3H), 0.92 (d, J = 6.7 Hz, 3H), 1.23–1.35 (m, 2H), 1.41,
2(S)-1-N-(tert-butoxycarbonyl)-4,4-di-n-propylpyrrolidine-2-
carboxylic acid (17)
Compound 16 (2.0 g, 5.19 mmol) in MeOH (23 ml) were treated for 4.5 h
according to the similar procedure as described for the preparation of 7 to
1.45 (s
x 2, 9H), 1.51–1.64 (m, 1H), 1.76–1.95 (m, 1H), 2.07–2.15
(m, 1H), 2.28–2.44 (m, 1H), 2.85–3.00 (m, 1H), 3.57–3.74 (m, 1H) and
4.18–4.32 (m, 1H).
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
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Table 4 Anti-bacterial activities (MIC, μg ml− 1) of 7-S-substituted 1′-N- and 4′-modified LCM derivatives (48 and 53–59) and TEL
afford 17 (1.55 g, quant) as an off-white oil. ESI-MS m/z 300 (M+H)+ as
C16H29NO4; 1H NMR (400 MHz, CD3OD) δ 0.91 (t, J = 6.9 Hz, 3H), 0.93 0.689 mmol) and stirred at room temperature for 4.5 h. The mixture was
′-dicyclohexylcarbodiimide (142.0 mg, 0.689 mmol) and MTL (174.0 mg,
(t, J =6.9 Hz, 3H), 1.17–1.48 (m, 8H), 1.42, 1.45 (s x 2, 9H), 1.64–1.75 (m,
1H), 2.11–2.24 (m, 1H), 3.10 (d, J = 10.6 Hz, 1H), 3.35–3.42 (m, 1H),
4.01–4.25 (m, 1H).
added to H2O and ethyl acetate. The desired compound was extracted with
ethyl acetate, and then the organic phase was washed with H2O, dried over
Na2SO4, filtrated and concentrated under reduced pressure. The resulting
residue was purified by silica gel column chromatography (hexane/ethyl
acetate = 1/1 to ethyl acetate only to ethyl acetate/MeOH = 24/1) to obtain
the title compound (245.0 mg, 88.5% in two steps from 10) as a colorless solid.
ESI-MS m/z 523 (M+H)+ as C23H42N2O9S; 1H NMR (400 MHz, CD3OD)
δ 1.15–1.29 (m, 3H), 1.44, 1.46 (s x 2, 9H), 1.36–1.66 (m, 4H), 1.73–1.88
(m, 1H), 2.06, 2.07 (s x 2, 3H), 2.09–2.17 (m, 1H), 2.33–2.50 (m, 1H), 2.93
(br t, J = 9.9 Hz, 1H), 3.32 (s, 3H), 3.40 (t, J = 6.3 Hz, 2H), 3.53–3.96 (m, 3H),
3.98–4.18 (m, 3H), 4.20–4.26 (m, 1H), 4.28–4.48 (m, 1H) and 5.24
(d, J = 5.6 Hz, 1H).
1′-N-(tert-butoxycarbonyl)-1′-demethyllincomycin (18)
To a solution of compound 7 (745.0 mg, 2.90 mmol) in DMF (27 ml) were
added 1-hydroxybenzotriazole (469.4 mg, 3.47 mmol), N,N′-dicyclohexylcar-
bodiimide (716.8 mg, 3.47 mmol) and MTL (1.10 g, 4.34 mmol) and stirred at
room temperature for 15 h. The mixture was added to H2O and ethyl acetate.
The desired compound was extracted with ethyl acetate, and then the organic
phase was washed with H2O, dried over Na2SO4, filtrated and concentrated
under reduced pressure to obtain the title compound. The total amount of this
compound was used without purification to synthesize 23. For the qualified
analytical purpose, the above crude compound 18 was purified by column
chromatography (ethyl acetate only) to obtain the title compound as a colorless
solid. FAB-MS m/z 493 (M+H)+ as C22H40N2O8S; 1H NMR (400 MHz,
CD3OD) δ 0.78–0.93 (m, 3H), 1.05–1.45 (m, 7H), 1.35, 1.38 (s x 2, 9H),
1.59–1.81 (m, 1H), 1.88–2.09 (m, 1H), 1.97 (s, 3H), 2.23–2.43 (m, 1H), 2.83
(br t, J = 10.1 Hz, 1H), 3.43–3.63 (m, 2H), 3.64–3.82 (m, 1H), 3.84–4.09
(m, 3H), 4.10–4.19 (m, 1H), 4.21–4.39 (m, 1H) and 5.14 (br d, J = 5.4 Hz, 1H).
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-i-
butyllincomycin (20)
To a solution of compound 13 (57.9 mg, 0.21 mmol) in DMF (1.0 ml) were
added 1-hydroxybenzotriazole (43.2 mg, 0.32 mmol), N,N′-dicyclohexylcarbo-
diimide (61.4 g, 0.32 mmol) and MTL (81.1 mg, 0.32 mmol) and stirred at
room temperature for 1 h. The mixture was added to the saturated aqueous
NaHCO3 and ethyl acetate. The desired compound was extracted with ethyl
acetate, and then the organic phase was dried over Na2SO4, filtrated and
concentrated under reduced pressure. The resulting residue was purified by
silica gel column chromatography (chloroform/MeOH= 10/1) to obtain the
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-(3-
methoxypropyl)lincomycin (19)
To a solution of compound 12 (152.3 mg, 0.53 mmol) in DMF (1.5 ml) title compound (100.2 mg, 92.7%) as a colorless solid. FAB-MS m/z 507
were added 1-hydroxybenzotriazole (93.0 mg, 0.689 mmol), N,N
(M+H)+ as C23H42N2O8S; 1H NMR (400 MHz, CD3OD) δ 0.87–0.98 (m, 6H),
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
11
Table 5 Anti-bacterial activities (MIC, μg ml− 1) of 7-S-substituted 1′-N- and 4′-modified LCM derivatives with an alternative 7-S-substituent
(67–69, 73 and 75)
1.16–1.32 (m, 6H), 1.44, 1.47 (s x 2, 9H), 1.51–1.66 (m, 1H), 1.70–1.86 was added to the saturated aqueous NaHCO3. The desired compound was
(m, 1H), 2.05, 2.06 (s x 2, 3H), 2.07–2.15 (m, 1H), 2.39–2.57 (m, 1H), 2.90
(t, J =10.1 Hz, 1H), 3.55–3.71 (m, 1H), 3.72–3.88 (m, 1H), 3.98–4.19 (m, 2H),
4.23 (d, J = 8.8 Hz, 1H), 4.32–4.51 (m, 1H) and 5.23 (d, J = 5.4 Hz, 1H).
extracted with ethyl acetate, washed with H2O and then the organic phase was
dried over Na2SO4, filtrated and concentrated under reduced pressure. To the
resulting residue were added methanol (16.4 ml) and 6 N acetic acid (0.87 ml),
and stirred at room temperature for 11 h. The mixture was added to the
saturated aqueous NaHCO3 and concentrated under reduced pressure to
remove MeOH. The desired compound was extracted with ethyl acetate, and
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-n-
pentyllincomycin (21)
Compound 14 (1.16 g, 4.05 mmol), 1-hydroxybenzotriazole (820 mg, then the organic phase was dried over Na2SO4, filtrated and concentrated under
6.07 mmol), N,N′-dicyclohexylcarbodiimide (1.25 g, 6.07 mmol) and MTL reduced pressure. The resulting residue was purified by silica gel column
(1.54 g, 6.07 mmol) in DMF (15.0 ml) were treated for 23 h according
to the similar procedure as described for the preparation of 18 to afford 21.
The total amount of this compound was used without purification to
synthesize 26.
chromatography (hexane/ethyl acetate= 2/1 to 1/2) to obtain the title com-
pound (1.45 g, 70.6% in three steps from 7) as a colorless solid. ESI-MS m/z
709 (M+H)+ as C31H64N2O8SSi3; 1H NMR (400 MHz, CD3OD) δ 0.12–0.26
(m, 27H), 0.85–1.00 (m, 3H), 1.07–1.25 (m, 3H), 1.26–1.41 (m, 4H), 1.44, 1.46
(s x 2, 9H), 1.66–1.93 (m, 1H), 2.03, 2.05 (s x 2, 3H), 1.98–2.42 (m, 2H),
2.88–3.02 (m, 1H), 3.54–4.40 (m, 8H) and 5.18 (d, J = 5.4 Hz, 1H).
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-{(E)-pent-2-
enyl}lincomycin (22)
Compound 15 (1.55 g, 5.47 mmol), 1-hydroxybenzotriazole (1.11 g,
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-
8.21 mmol), N,N′-dicyclohexylcarbodiimide (1.69 g, 8.21 mmol) and MTL
(2.08 mg, 8.21 mmol) in DMF (23 ml) were treated for 3 h according to the (3-methoxypropyl)-2,3,4-tris-O-(trimethylsilyl)lincomycin (24)
similar procedure as described for the preparation of 18 to afford 22. The total Compound 19 (290 mg, 0.56 mmol), trimethylchlorosilane (355 μl,
amount of this compound was used without purification to synthesize 27.
2.77 mmol) and hexamethyldisilazane (581 μl, 2.77 mmol) in pyridine
(1.0 ml) were treated for 1.0 h according to the similar procedure as described
for the preparation of 23, and then the crude compound and 6 N acetic acid
(167 μl) in methanol (3.1 ml) were treated for 30 min according to the similar
procedure as described for the preparation of 23 to afford 24 (282 mg, 68.7% in
two steps from 19) as a colorless solid. ESI-MS m/z 739 (M+H)+ as
1′-N-(tert-butoxycarbonyl)-1′-demethyl-2,3,4-tris-O-(trimethylsilyl)
lincomycin (23)
To a solution of compound 18 (crude) in pyridine (15 ml) were added
trimethylchlorosilane (1.85 ml, 14.5 mmol) and hexamethyldisilazane (3.03 ml,
14.5 mmol) and stirred at room temperature for 30 min, and then the solution C32H66N2O9SSi3.
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
12
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-i-butyl-
2,3,4-tris-O-(trimethylsilyl)lincomycin (25)
obtain 7(S)-7-(6-aminobenzothiazol-2-yl)thio-1′-N-(tert-butoxycarbonyl)-1′-
demethyl-7-deoxy-2,3,4-tris-O-(trimethylsilyl)lincomycin (197.2 mg, crude).
To the solution of this intermediate in MeOH (2 ml) was added 4 N HCl-
ethyl acetate (2.5 ml) and stirred at room temperature for 2 h. The solution was
concentrated under reduced pressure. The resulting residue was purified by
silica gel column chromatography (CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2)
to obtain the title compound (96.4 mg, 61.4% in three steps from 23) as an off-
white solid. [α]D26+92.1° (c 2.49, MeOH); ESI-MS m/z 557 (M+H)+ as
C24H36N4O5S3; TOF-ESI-HRMS (M+H)+ calcd. for C24H36N4O5S3: 557.1926,
found: 557.1920; 1H NMR (400 MHz, CD3OD) δ 0.86–0.96 (m, 3H), 1.25–1.40
(m, 4H), 1.49 (d, J = 6.9 Hz, 3H), 1.69–1.82 (m, 1H), 1.93 (s, 3H), 1.96–2.13
(m, 2H), 2.52 (dd, J = 10.4, 8.1 Hz, 1H), 3.20 (dd, J = 10.4, 6.9 Hz, 1H), 3.58
(dd, J = 10.2, 3.2 Hz, 1H), 3.80–3.87 (m, 2H), 4.11 (dd, J = 10.2, 5.6 Hz, 1H),
4.27 (dq, J = 6.9, 2.7 Hz, 1H), 4.39 (br dd, J = 10.0, 0.9 Hz, 1H), 4.57
(dd, J = 10.0, 2.7 Hz, 1H), 5.26 (d, J = 5.6 Hz, 1H), 6.85 (dd, J = 8.7, 2.1 Hz,
1H), 7.08 (d, J = 2.1 Hz, 1H) and 7.59 (d, J = 8.7 Hz, 1H).
Compound 20 (652 mg, 1.63 mmol), trimethylchlorosilane (1.02 ml,
8.02 mmol) and hexamethyldisilazane (1.68 ml, 8.02 mmol) in pyridine
(3.5 ml) were treated for 1 h according to the similar procedure as described
for the preparation of 23, and then the crude compound and 6 N acetic acid
(480 μl) in methanol (9 ml) were treated for 30 min according to the similar
procedure as described for the preparation of 23 to afford 25 (946 mg, 79.8% in
two steps from 20) as a colorless solid. FAB-MS m/z 723 (M+H)+ as
C32H66N2O8SSi3; 1H NMR (400 MHz, CDCl3) δ 0.11–0.21 (m, 27H), 0.90
(d, J = 6.6 Hz, 6H), 1.05–1.33 (m, 5H), 1.49 (s, 9H), 1.50–1.61 (m, 2H), 2.07
(s, 3H), 2.13–2.57 (m, 1H), 2.72–3.13 (m, 1H), 3.40–3.82 (m, 3H), 3.94–4.19
(m, 3H), 4.22–4.40 (m, 2H) and 5.19 (d, J = 5.6 Hz, 1H).
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-n-pentyl-
2,3,4-tris-O-(trimethylsilyl)lincomycin (26)
Compound 21 (crude), trimethylchlorosilane (2.6 ml, 20.3 mmol) and hexam-
ethyldisilazane (4.24 ml, 20.3 mmol) in pyridine (10.0 ml) were treated for 1 h
according to the similar procedure as described for the preparation of 23, and
then the crude compound and 6 N acetic acid (1.21 ml) in methanol (23 ml)
were treated for 2.0 h according to the similar procedure as described for the
preparation of 23 to afford 26 (2.21 g, 74% in three steps from 14) as a
colorless solid. FAB-MS m/z 737 (M+H)+ as C33H68N2O8SSi3; 1H NMR
(400 MHz, CDCl3) δ 0.07–0.25 (m, 27H), 0.78–0.97 (m, 3H), 1.05–1.42
(m, 11H), 1.48 (s, 9H), 2.07 (s, 3H), 2.10–3.20 (m, 4H), 3.40–3.90 (m, 3H),
3.92–4.20 (m, 3H), 4.23–4.47 (m, 2H) and 5.19 (br d, J = 5.4 Hz, 1H).
7(S)-7-(5-amino-1,3,4-thiadiazol-2-ylthio)-7-deoxy-1′-
demethyllincomycin (33)
To a solution of compound 23 (200 mg, 0.28 mmol) in THF (2 ml) at 0 °C
were added triphenylphosphine (138.0 mg, 0.53 mmol), diethylazodicarboxy-
late (96 μl, 0.53 mmol), 5-(tert-butoxycarbonylamino)-1,3,4-thiadiazole-2-thiol
(126.9 mg, 0.54 mmol) and stirred at room temperature for 3 h. To the
solution was added 1 N HCl (1 ml)–MeOH (1 ml), and stirred at room
temperature for 50 min. The solution was added to the saturated aqueous
NaHCO3. The desired compound was extracted with ethyl acetate, and then the
organic phase was dried over Na2SO4, filtrated and concentrated under reduced
pressure. The resulting residue was purified by preparative TLC (CHCl3/
MeOH/28% aq. NH4OH= 9/2/0.2) to obtain 7(S)-7-[5-{(tert-butoxycarbonyl)
amino}-1,3,4-thiadiazol-2-ylthio]-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-
deoxylincomycin as a colorless solid (146.6 mg, 73.4%). 1H NMR (400 MHz,
CD3OD) δ 0.85–0.98 (m, 3H), 1.25–1.60 (m, 25 H), 1.80–1.97 (m, 1H),
1.98–2.17 (m, 1H), 2.06, 2.10 (s x 2, 3H), 2.22–2.40 (m, 1H), 2.89–3.05
(m, 1H), 3.50–3.60 (m, 1H), 3.69–3.82 (m, 1H), 3.84–4.00 (m, 1H), 4.02–4.20
(m, 2H), 4.26–4.42 (m, 2H), 4.45–4.60 (m, 1H) and 5.27 (br d, J = 5.4 Hz, 1H).
To the solution of this intermediate (146.6 mg, 0.21 mmol) in MeOH
(1.4 ml) was added 4 N HCl-ethyl acetate (1.7 ml), and stirred at room
temperature for 2 h. The solution was concentrated under reduced pressure.
The resulting residue was purified by preparative TLC (CHCl3/MeOH/28% aq.
NH4OH= 9/2/0.2) to obtain the title compound (25.4 mg, 24.2%) as a
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-{(E)-pent-2-
enyl}-2,3,4-tris-O-(trimethylsilyl)lincomycin (27)
Compound 22 (crude), trimethylchlorosilane (3.50 ml, 27.4 mmol) and
hexamethyldisilazane (5.70 ml, 27.4 mmol) in pyridine (10 ml) were treated
for 1 h according to the similar procedure as described for the preparation of 23
and then, the crude compound and 6 N acetic acid (1.64 ml) in methanol
(31 ml) were treated for 1.0 h according to the similar procedure as described
for the preparation of 23 to afford 27 (3.29 g, 81.8% in three steps from 15) as
a colorless solid. 1H NMR (400 MHz, CDCl3) δ 0.02–0.28 (m, 27H), 0.96
(t, J =7.4 Hz, 3H), 1.08–1.25 (m, 3H), 1.48 (s, 9H), 1.89–2.51 (m, 6H), 2.02
(s, 3H), 2.66–3.26 (m, 2H), 3.40–3.64 (m, 2H), 3.68–4.19 (m, 4H), 4.22–4.50
(m, 2H), 5.19 (br d, J = 5.1 Hz, 1H), 5.26–5.39 (m, 1H) and 5.43–5.59 (m, 1H).
25
colorless solid. [α]D +101° (c 0.33, MeOH); ESI-MS m/z 508 (M+H)+ as
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-7-[5-{5-
(methylamino)thiazol-4-yl}-1,3,4-thiadiazol-2-ylthio]-2,3,4-tris-O-
(trimethylsilyl)lincomycin (31)
C19H33N5O5S3; TOF-ESI-HRMS (M+H)+ calcd. for C19H33N5O5S3: 508.1722,
found: 508.1719; 1H NMR (400 MHz, CD3OD) δ 0.89–0.98 (m, 3H), 1.33–1.45
(m, 4H), 1.37 (d, J = 7.0 Hz, 3H), 1.84–1.95 (m, 1H), 2.03–2.18 (m, 2H), 2.11
(s, 3H), 2.66 (dd, J = 10.6, 8.3 Hz, 1H), 3.30–3.36 (m, 1H), 3.56 (dd, J =10.2,
3.2 Hz, 1H), 3.81 (br dd, J = 3.2, 0.7 Hz, 1H), 3.96 (dq, J = 7.0, 2.6 Hz, 1H),
4.00 (dd, J = 9.3, 4.0 Hz, 1H), 4.09 (dd, J = 10.2, 5.6 Hz, 1H), 4.37 (br dd,
J = 10.0, 0.7 Hz, 1H), 4.52 (dd, J = 10.0, 2.6 Hz, 1H) and 5.27
(d, J = 5.6 Hz, 1H).
To a solution of compound 23 (200 mg, 0.28 mmol) in THF (2 ml) at 0 °C
were added triphenylphosphine (110.9 mg, 0.42 mmol), diethylazodicarboxy-
late (77 μl, 0.42 mmol), 5-{5-(methylamino)thiazol-4-yl}-1,3,4-thiadiazole-2-
thiol (100.7 mg, 0.44 mmol) and stirred at room temperature for 18 h. The
solution was purified by preparative TLC (hexane/ethyl acetate= 2/1) to obtain
the title compound as an off-white solid (88.8 mg, 34.2%). FAB-MS m/z 921
(M+H)+ as C37H68N6O7S4Si3; 1H NMR (400 MHz, CDCl3) δ 0.00–0.25
(m, 27H), 0.80–1.00 (m, 3H), 1.08–1.67 (m, 16H), 1.74–2.99 (m, 7H),
3.02–3.22 (m, 3H), 3.43–3.90 (m, 3H), 3.98–4.50 (m, 4H), 4.60–4.94
(m, 1H), 5.20 (br d, J = 5.4 Hz, 1H) and 7.85–8.00 (br s, 1H).
7(S)-1′-demethyl-7-deoxy-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-
ylthio}lincomycin (34)
To a solution of compound 23 (200 mg, 0.28 mmol) in THF (2 ml) at 0 °C
were added triphenylphosphine (110.9 mg, 0.42 mmol), diethylazodicarboxy-
late (77 μl, 0.42 mmol), 5-(2-nitrophenyl)-1,3,4-thiadiazole-2-thiol (104.6 mg,
0.44 mmol), and stirred at room temperature for 7 h. The solution was added
to the saturated aqueous NaHCO3. The desired compound was extracted with
ethyl acetate, and then the organic phase was dried over Na2SO4, filtrated and
concentrated under reduced pressure. To the resulting residue was added
MeOH (4 ml)–1N HCl (1 ml) and stirred at room temperature for 2.5 h. The
solution was added to the saturated aqueous NaHCO3. The desired compound
was extracted with ethyl acetate, and then the organic phase was dried over
7(S)-7-(6-aminobenzothiazol-2-ylthio)-7-deoxy-1′-
demethyllincomycin (32)
To a solution of compound 23 (200 mg, 0.28 mmol) in THF (2 ml) at 0 °C
were added triphenylphosphine (110.9 mg, 0.42 mmol), diethylazodicarboxy-
late (77 μl, 0.42 mmol), 6-aminobenzothiazole-2-thiol (79.7 mg, 0.44 mmol)
and stirred at room temperature for 4 h. To the solution was added 1 N HCl
(1 ml)–MeOH (1 ml) and stirred at room temperature for 30 min. The solution
was added to the saturated aqueous NaHCO3. The desired compound was Na2SO4, filtrated and concentrated under reduced pressure. The resulting
extracted with ethyl acetate, and then the organic phase was dried over Na2SO4,
residue was purified by preparative TLC (CHCl3/MeOH/28% aq. NH4OH= 9
filtrated and concentrated under reduced pressure. The resulting residue was /2/0.2) to obtain 7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-7-{5-
purified by preparative TLC (CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2) to (2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}lincomycin (164.9 mg as crude). To
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
13
the solution of this crude compound (63.9 mg) in MeOH (0.6 ml) was added (d, J = 6.9 Hz, 3H), 1.69–1.81 (m, 1H), 1.99 (s, 3H), 1.97–2.07 (m, 1H),
4 N HCl-ethyl acetate (0.75 ml), and stirred at room temperature for 2.5 h. The 2.07–2.20 (m, 1H), 2.20–2.31 (m, 1H), 2.76–2.90 (m, 1H), 3.26–3.34 (m, 1H),
solution was concentrated under reduced pressure. The resulting residue was
purified by preparative TLC (CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2) to
obtain the title compound (13.0 mg, 19.4% in three steps from 23) as a
3.39–3.52 (m, 1H), 3.57 (dd, J = 10.2, 3.2 Hz, 1H), 3.82 (br dd, J = 3.2, 0.8 Hz,
1H), 4.10 (dd, J = 10.2, 5.6 Hz, 1H), 4.40 (br dd, J =9.3, 0.8 Hz, 1H), 4.51
(dq, J = 6.9, 3.4 Hz, 1H), 4.59 (dd, J = 9.3, 3.4 Hz, 1H), 5.26 (d, J = 5.6 Hz, 1H),
7.74–7.86 (m, 3H) and 8.06–8.12 (m, 1H).
colorless solid. [α]D +37.1° (c 0.21, MeOH); ESI-MS m/z 614 (M+H)+ as
26
C25H35N5O7S3; TOF-ESI-HRMS (M+H)+ calcd. for C25H35N5O7S3: 614.1777,
found: 614.1778; 1H NMR (400 MHz, CD3OD) δ 0.83–0.99 (m, 3H), 1.30–1.45
(m, 4H), 1.56 (d, J = 7.0 Hz, 3H), 1.88–1.98 (m, 1H), 1.99 (s, 3H), 2.07–2.25
(m, 2H), 2.69 (br dd, J = 10.6, 8.4 Hz, 1H), 3.32–3.42 (m, 1H), 3.56
(dd, J =10.2, 3.2 Hz, 1H), 3.82–3.88 (m, 1H), 4.00–4.10 (m, 1H), 4.10
(dd, J = 10.2, 5.6 Hz, 1H), 4.36–4.46 (m, 1H), 4.47 (dq, J =7.0, 2.5 Hz, 1H),
4.66 (dd, J =10.0, 2.5 Hz, 1H), 5.28 (d, J = 5.6 Hz, 1H), 7.74–7.87 (m, 3H) and
8.05–8.15 (m, 1H).
7(S)-1′-N-{2-(tert-butyldimethylsilyloxy)ethyl}-1′-demethyl-7-deoxy-
7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}lincomycin (39)
Compound 34 (49.2 mg, 0.08 mmol), 2-(tert-butyldimethylsilyloxy)acetalde-
hyde (23 μl, 0.12 mmol), AcOH (one drop) and NaBH(OAc)3 (34.2 mg,
0.16 mmol) in 1,2-dichloroethane (1 ml) were treated at 0 °C for 15 h
according to the similar procedure as described for the preparation of 38 to
afford 39 (26.9 mg, 44.0%) as a colorless solid. FAB-MS m/z 772 (M+H)+ as
C33H53N5O8S3Si; 1H NMR (400 MHz, CD3OD) δ 0.07 (s, 3H), 0.08 (s, 3H),
0.82–0.98 (m, 12H), 1.25–1.42 (m, 4H), 1.59 (d, J = 6.8 Hz, 1H), 1.68–1.87
(m, 1H), 1.94–2.05 (m, 1H), 1.97 (s, 3H), 2.07–2.21 (m, 2H), 2.54–2.92
(m, 2H), 3.37–3.44 (m, 1H), 3.56 (dd, J = 10.2, 3.2 Hz, 1H), 3.71–3.92 (m, 4H),
4.10 (dd, J = 10.2, 5.6 Hz, 1H), 4.35–4.44 (m, 1H), 4.47–4.56 (m, 1H),
4.58–4.65 (m, 1H), 5.26 (d, J = 5.6 Hz, 1H), 7.74–7.86 (m, 3H) and
8.06–8.13 (m, 1H).
7(S)-1′-demethyl-7-deoxy-7-[5-{5-(methylamino)thiazol-4-yl}-1,3,4-
thiadiazol-2-ylthio]lincomycin (35)
To the solution of compound 31 (88.8 mg 0.096 mmol) in MeOH (0.5 ml) was
added 4 N HCl-ethyl acetate (0.79 ml), stirred at 0 °C for 1 h and then stirred at
room temperature for 3.5 h. The solution was concentrated under reduced
pressure. The resulting residue was purified by preparative TLC (CHCl3/
MeOH/28% aq. NH4OH= 9/2/0.2) to obtain the title compound (39.8 mg,
26
68.3%) as an off-white solid. [α]D +69.5° (c 0.60, MeOH); ESI-MS m/z 605
7(S)-1′-demethyl-7-deoxy-1′-N-(2-hydroxyethyl)-7-{5-(2-
nitrophenyl)-1,3,4-thiadiazol-2-ylthio}lincomycin (40)
(M+H)+ as C23H36N6O5S4; TOF-ESI-HRMS (M+H)+ calcd. for
C23H36N6O5S4: 605.1708, found: 605.1706; 1H NMR (400 MHz, CD3OD)
δ 0.86–0.95 (m, 3H), 1.29–1.41 (m, 4H), 1.49 (d, J = 6.9 Hz, 3H), 1.78–1.87
(m, 1H), 1.98–2.14 (m, 2H), 2.01 (s, 3H), 2.56 (dd, J =10.5, 8.1 Hz, 1H), 3.11
(s, 3H), 3.25 (dd, J = 10.5, 7.0 Hz, 1H), 3.56 (dd, J = 10.3, 3.2 Hz, 1H), 3.82
(br dd, J = 3.2, 0.9 Hz, 1H), 3.86 (dd, J = 9.2, 3.9 Hz, 1H), 4.09 (dd, J = 10.3,
5.6 Hz, 1H), 4.27 (dq, J = 6.9, 2.7 Hz, 1H), 4.39 (br dd, J = 10.0, 0.9 Hz, 1H),
4.59 (dd, J = 10.0, 2.7 Hz, 1H), 5.26 (d, J = 5.6 Hz, 1H) and 8.12 (s, 1H).
To a solution of compound 39 (26.9 mg, 0.035 mmol) in THF (0.5 ml) at 0 °C
were added 1M THF solution of tetra-n-butyl ammonium fluoride (100 μl,
0.10 mmol) and stirred at room temperature for 15 h. The mixture was
concentrated under reduced pressure. The resulting residue was purified by
preparative TLC (CHCl3/MeOH/28% aq NH4OH= 10/1/0.1) to obtain the title
25
compound (16.5 mg, 72%) as a colorless solid. [α]D +70.5° (c 0.22, MeOH);
ESI-MS m/z 658 (M+H)+ as C27H39N5O8S3; TOF-ESI-HRMS (M+H)+ calcd.
for C27H39N5O8S3: 658.2039, found: 658.2044; 1H NMR (400 MHz, CD3OD)
δ 0.87–0.96 (m, 3H), 1.29–1.43 (m, 4H), 1.60 (d, J = 6.9 Hz, 3H), 1.79–1.93
(m, 1H), 1.99 (s, 3H), 2.02–2.10 (m, 1H), 2.10–2.23 (m, 2H), 2.64–2.75
(m, 1H), 2.83–2.96 (m, 1H), 3.31–3.40 (m, 1H), 3.40–3.50 (m, 1H), 3.56
(dd, J = 10.3, 3.2 Hz, 1H), 3.63–3.77 (m, 2H), 3.83 (dd, J = 3.2, 0.8 Hz, 1H),
4.10 (dd, J =10.3, 5.6 Hz, 1H), 4.45 (br dd, J = 9.9, 0.8 Hz, 1H), 4.51 (dq,
J = 6.9, 2.9 Hz, 1H), 4.63 (dd, J = 9.9, 2.9 Hz, 1H), 5.26 (d, J = 5.6 Hz, 1H),
7.74–7.86 (m, 3H) and 8.06–8.12 (m, 1H).
7(S)-7-deoxy-7-[5-{5-(methylamino)thiazol-4-yl}-1,3,4-thiadiazol-2-
ylthio]lincomycin (37)
Compound 36 (240 mg, 0.39 mmol), triphenylphosphine (150.0 mg,
0.57 mmol), diethylazodicarboxylate (100 μl, 0.64 mmol) and 5-{5-(methyla-
mino)thiazol-4-yl}-1,3,4-thiadiazole-2-thiol (150.0 mg, 0.65 mmol) in THF
(5 ml) were treated for 2 h, and then to the solution was added 1N HCl
(0.5 ml)–MeOH (5 ml) and stirred at room temperature for 1 h. The solution
was then added to the saturated aqueous NaHCO3. The desired compound was
extracted with ethyl acetate, and then the organic phase was dried over Na2SO4,
filtrated and concentrated under reduced pressure. The resulting residue was
purified by preparative TLC (CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2) to
obtain the title compound 37 (88.2 mg, 37% in two steps) as an off-white solid.
7(S)-1′-N-{2-(tert-butyldimethylsilyloxy)ethyl}-1′-demethyl-7-
deoxy-7-[5-{5-(methylamino)thiazol-4-yl}-1,3,4-thiadiazol-2-ylthio]
lincomycin (41)
[α]D +125° (c 0.89, MeOH); ESI-MS m/z 619 (M+H)+ as C24H38N6O5S4;
26
Compound 35 (74.3 mg, 0.12 mmol), 2-(tert-butyldimethylsilyloxy)acetalde-
hyde (34 μl, 0.18 mmol), AcOH (one drop) and NaBH(OAc)3 (51.0 mg,
0.24 mmol) in 1,2-dichloroethane (1 ml) were treated at room temperature
according to the similar procedure as described for the preparation of 38 to
afford 41 (54.8 mg, 60%) as a colorless solid. FAB-MS m/z 763 (M+H)+ as
C31H54N6O6S4Si; 1H NMR (400 MHz, CD3OD) δ 0.05 (s, 3H), 0.06 (s, 3H),
0.78–1.00 (m, 12H), 1.23–1.42 (m, 4H), 1.54 (d, J = 7.1 Hz, 3H), 1.72–1.86
(m, 1H), 1.92–2.05 (m, 1H), 1.99 (s, 3H), 2.08–2.22 (m, 2H), 2.50–2.87
(m, 2H), 3.12 (s, 3H), 3.25–3.30 (m, 1H), 3.36–3.44 (m, 1H), 3.52–3.60
(m, 1H), 3.68–3.88 (m, 3H), 4.10 (dd, J = 10.2, 5.6 Hz, 1H), 4.30–4.44 (m, 2H),
4.54–4.62 (m, 1H), 5.26 (d, J = 5.6 Hz, 1H) and 8.13 (s, 1H).
TOF-ESI-HRMS (M+H)+ calcd. for C24H38N6O5S4: 619.1865, found: 619.1860;
1H NMR (400 MHz, CD3OD) δ 0.82–0.98 (m, 3H), 1.21–1.39 (m, 4H), 1.53
(d, J =6.9 Hz, 3H), 1.78–1.89 (m, 1H), 1.92–2.08 (m, 2H), 2.02 (s, 3H),
2.09–2.25 (m, 1H), 2.35 (s, 3H), 3.00 (dd, J = 10.5, 5.0 Hz, 1H), 3.13 (s, 3H),
3.19 (dd, J = 8.5, 6.2 Hz, 1H), 3.59 (dd, J = 10.2, 3.2 Hz, 1H), 3.77–3.85
(m, 1H), 4.11 (dd, J =10.2, 5.6 Hz, 1H), 4.27 (dq, J = 6.9, 3.0 Hz, 1H), 4.44
(br dd, J = 9.8, 0.5 Hz, 1H), 4.57 (dd, J =9.8, 3.0 Hz, 1H), 5.27 (d, J = 5.6 Hz,
1H) and 8.13 (s, 1H).
7(S)-1′-demethyl-7-deoxy-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-
yl}thio-1′-N-i-propyllincomycin (38)
7(S)-1′-demethyl-7-deoxy-1′-N-(2-hydroxylethyl)-7-[5-{5-
(methylamino)thiazol-4-yl}-1,3,4-thiadiazol-2-ylthio]lincomycin
(42)
Compound 41 (54.8 mg, 0.072 mmol) and 1 M THF solution of tetra-n-butyl
ammonium fluoride (200 μl, 0.20 mmol) in THF (1.0 ml) were treated at 0 °C
for 1 h and then treated at room temperature for 5 h according to the similar
procedure as described for the preparation of 40 to afford 42 (31.3 mg, 67.0%)
as a colorless solid. [α]D25 +51.1° (c 0.27, MeOH); ESI-MS m/z 649 (M+H)+ as
To a solution of compound 34 (30.5 mg, 0.05 mmol) in 1,2-dichloroethane
(1 ml) at 0 °C were added acetone (40 μl, 0.054 mmol), AcOH (one drop) and
NaBH(OAc)3 (21.7 mg, 0.10 mmol) and stirred at room temperature for 15 h.
The mixture was concentrated under reduced pressure. The resulting residue
was purified by preparative TLC (CHCl3/MeOH/28% aq NH4OH=10/1/0.1)
and then by LH-20 (CHCl3/MeOH =1/1) to obtain the title compound
26
(20.1 mg, 61%) as a colorless solid. [α]D +76.8° (c 0.59, MeOH); ESI-MS
m/z 656 (M+H)+ as C28H41N5O7S3; TOF-ESI-HRMS (M+H)+ calcd. for
C28H41N5O7S3: 656.2246, found: 656.2243; 1H NMR (400 MHz, CD3OD) C25H40N6O6S4; TOF-ESI-HRMS (M+H)+ calcd. for C25H40N6O6S4: 649.1970,
δ
0.86–0.98 (m, 3H), 1.06–1.16 (m, 6H), 1.28–1.42 (m, 4H), 1.58 found: 649.1973; 1H NMR (400 MHz, CD3OD) δ 0.88–0.96 (m, 3H), 1.30–1.40
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
14
(m, 4H), 1.54 (d, J = 6.9 Hz, 3H), 1.79–1.90 (m, 1H), 1.97–2.08 (m, 1H), 2.00 chromatography (ethyl acetate only) to obtain the title compound as a colorless
(s, 3H), 2.09–2.21 (m, 2H), 2.62–2.72 (m, 1H), 2.83–2.93 (m, 1H), 3.11 solid. ESI-MS m/z 535 (M+H)+ as C25H46N2O8S; 1H NMR (400 MHz,
(s, 3H), 3.30–3.37 (m, 1H), 3.39–3.45 (m, 1H), 3.56 (dd, J = 10.2, 3.2 Hz, 1H),
3.65–3.74 (m, 2H), 3.81 (br dd, J =3.2, 0.8 Hz, 1H), 4.09 (dd, J = 10.2, 5.6 Hz,
CD3OD) δ 0.76–0.90 (m, 6H), 1.04–1.32 (m, 11H), 1.35, 1.36 (s x 2, 9H),
1.57–1.72 (m, 1H), 1.97, 1.99 (s x 2, 3H), 2.00–2.15 (m, 1H), 3.03 (br t,
1H), 4.33 (dq, J = 6.9, 2.8 Hz, 1H), 4.43 (br dd, J = 9.8, 0.8 Hz, 1H), 4.59 J = 10.4 Hz, 1H), 3.29–3.56 (m, 2H), 3.67–3.90 (m, 1H), 3.91–4.36 (m, 5H)
and 5.15 (br d, J = 5.4 Hz, 1H).
(dd, J = 9.8, 2.8 Hz, 1H), 5.25 (d, J = 5.6 Hz, 1H) and 8.11 (s, 1H).
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-propyl-2,3,4-tris-O-
(trimethylsilyl)lincomycin (47)
7(S)-1′-demethyl-7-deoxy-1′-N-{2(R)-hydroxypropyl}-7-[5-{5-
(methylamino)thiazol-4-yl}-1,3,4-thiadiazol-2-ylthio]lincomycin (43)
To a solution of compound 35 (28.7 mg, 0.048 mmol) and N,N-diisopropy-
lethylamine (10.0 μl, 0.057 mmol) in MeOH (1 ml) at 0 °C was added (R)-2-
methyloxirane (0.30 ml, 4.3 mmol) and stirred at 0 °C for 96 h. The mixture
was concentrated under reduced pressure. The resulting residue was purified by
preparative TLC (CHCl3/MeOH/28% aq. NH4OH= 10/1/0.1) to obtain the
Compound 46 (crude), trimethylchlorosilane (3.32 ml, 25.9 mmol) and
hexamethyldisilazane (5.44 ml, 25.9 mmol) in pyridine (5.0 ml) were treated
for 1 h according to the similar procedure as described for the preparation of 23
and then the crude compound and 6 N acetic acid (1.55 ml) in methanol
(29.4 ml) were treated for 1 h according to the similar procedure as described
for the preparation of 23 to afford 47 (1.66 g, 41.6% in three steps from 17) as
a colorless solid. ESI-MS m/z 751 (M+H)+ as C34H70N2O8SSi3; 1H NMR
(400 MHz, CDCl3) δ 0.14 (s, 18H), 0.18 (s, 9H), 0.82–0.98 (m, 6H), 1.08–1.35
(m, 11H), 1.46 (s, 9H), 1.80–2.35 (m, 1H), 2.06 (s, 3H), 2.66–3.30 (m, 2H),
3.36–4.41 (m, 8H) and 5.13–5.24 (m, 1H).
26
title compound (10.6 mg, 33%) as a colorless solid. [α]D +29.2° (c 0.15,
MeOH); ESI-MS m/z 663 (M+H)+ as C26H42N6O6S4; TOF-ESI-HRMS (M+H)
+
calcd. for C26H42N6O6S4: 663.2127, found: 663.2127; 1H NMR (400 MHz,
CD3OD) δ 0.87–0.96 (m, 3H), 1.16 (d, J = 6.2 Hz, 3H), 1.27–1.42 (m, 4H),
1.55 (d, J = 6.9 Hz, 1H), 1.78–1.87 (m, 1H), 1.98–2.27 (m, 3H), 1.99 (s, 3H),
2.43–2.55 (m, 1H), 2.56–2.66 (m, 1H), 3.11 (s, 3H), 3.39–3.46 (m, 1H), 3.55
(dd, J = 10.3, 3.2 Hz, 1H), 3.83 (br dd, J = 3.2, 0.9 Hz, 1H), 3.86–3.97 (m, 1H),
4.10 (dd, J = 10.3, 5.7 Hz, 1H), 4.33 (dq, J = 6.9, 2.9 Hz, 1H), 4.42–4.48
(m, 1H), 4.52–4.59 (m, 1H), 4.61 (dd, J = 9.9, 2.9 Hz, 1H), 5.25 (d, J = 5.7 Hz,
1H) and 8.11 (s, 1H).
7(S)-1′-demethyl-7-deoxy-4′-n-propyl-7-{5-(2-nitrophenyl)-1,3,4-
thiadiazol-2-ylthio}lincomycin (48)
To a solution of compound 47 (400 mg, 0.53 mmol) in THF (4 ml) at 0˚C were
added triphenylphosphine (209.6 mg, 0.80 mmol), diethylazodicarboxylate
(0.15 ml, 0.80 mmol), 5-(2-nitrophenyl)-1,3,4-thiadiazole-2-thiol (296.7 mg,
1.24 mmol) and stirred at room temperature for 6 h. The solution was purified
by preparative TLC (hexane/ethyl acetate= 2/1) to obtain 7(S)-1′-N-(tert-
butoxycarbonyl)-1′-demethyl-7-deoxy-4′-n-propyl-7-{5-(2-nitrophenyl)-1,3,4-
thiadiazol-2-ylthio}-2,3,4-tris-O-(trimethylsilyl)lincomycin (235.4 mg with
unseparable impurity). To this crude compound (235.4 mg 0.24 mmol) was
added 2,2,2-trifluoroacetic acid (1 ml) at 0 °C and stirred at room temperature
for 30 min. The solution was concentrated under reduced pressure. The
resulting residue was purified by preparative TLC (CHCl3/MeOH/28% aq
NH4OH= 9/2/0.2) to obtain the title compound (57.3 mg, 36.1% in 2 steps
7(S)-1′-N-acetyl-1′-demethyl-7-deoxy-7-[5-{5-(methylamino)
thiazol-4-yl}-1,3,4-thiadiazol-2-ylthio]lincomycin (44)
To a solution of compound 35 (30.2 mg, 0.050 mmol) in MeOH (0.5 ml) at 0 °
C was added acetic anhydride (7.0 μl, 0.074 mmol) and stirred at 0 °C for 1.5 h.
The mixture was concentrated under reduced pressure. The resulting residue
was purified by preparative TLC (CHCl3/MeOH/28% aq. NH4OH= 10/1/0.1)
25
to obtain the title compound (10.8 mg, 33%) as an off-white solid. [α]D
+56.5° (c 1.25, MeOH); ESI-MS m/z 647 (M+H)+ as C25H38N6O6S4; TOF-ESI-
HRMS (M+H)+ calcd. for C25H38N6O6S4: 647.1814, found: 647.1807; 1H NMR
26
from 47) as a colorless solid. [α]D +91.0° (c 0.40, MeOH); ESI-MS m/z 656
(400 MHz, CD3OD)
δ 0.87–0.98 (m, 3H), 1.25–1.42 (m, 4H), 1.49
(M+H)+ as C28H41N5O7S3; TOF-ESI-HRMS (M+H)+ calcd. for
C28H41N5O7S3: 656.2246, found: 656.2239; 1H NMR (400 MHz, CD3OD)
δ 0.86–0.97 (m, 6H), 1.22–1.42 (m, 8H), 1.56 (d, J = 6.8 Hz, 3H), 1.63
(dd, J = 13.0, 8.2 Hz, 1H), 2.00 (s, 3H), 2.11–2.19 (m, 1H), 2.79–2.88 (m, 2H),
3.56 (dd, J = 10.2, 3.2 Hz, 1H), 3.80–3.86 (m, 1H), 3.93 (t, J = 8.4 Hz, 1H), 4.10
(dd, J = 10.2, 5.6 Hz, 1H), 4.38–4.43 (m, 1H), 4.45 (dq, J = 6.8, 2.7 Hz, 1H),
4.64 (dd, J = 10.0, 2.7 Hz, 1H), 5.27 (d, J = 5.6 Hz, 1H), 7.75–7.86 (m, 3H) and
8.07–8.13 (m, 1H).
(d, J = 7.0 Hz, 3H), 1.82–1.95 (m, 1H), 1.98 (s, 3H), 2.01–2.08 (m, 1H), 2.09
(s, 3H), 2.35–2.50 (m, 1H), 3.12 (s, 3H), 3.14–3.20 (m, 1H), 3.56 (dd, J = 10.2,
3.3 Hz, 1H), 3.79–3.87 (m, 1H), 3.99 (br dd, J = 3.3, 1.0 Hz, 1H), 4.09
(dd, J = 10.2, 5.6 Hz, 1H), 4.27 (dq, J = 7.0, 2.4 Hz, 1H), 4.36–4.43 (m, 1H),
4.48 (dd, J = 8.8, 2.7 Hz, 1H), 4.61 (dd, J =10.0, 2.4 Hz, 1H) and 8.12 (s, 1H).
7(S)-1′-demethyl-7-deoxy-7-[5-{5-(methylamino)thiazol-4-yl}-1,3,4-
thiadiazol-2-ylthio]-1′-N-(4-methylthiazol-5-ylmethyl)lincomycin (45)
Compound 35 (24.0 mg, 0.04 mmol), 4-methylthiazole-5-carbaldehyde
(16.2 mg, 0.13 mmol), AcOH (one drop) and NaBH(OAc)3 (25.5 mg,
0.12 mmol) in MeOH (0.5 ml) were treated at room temperature for 15 h
according to the similar procedure as described for the preparation of 38 to
afford 45 (6.4 mg, 22.0%) as a colorless solid. [α]D26 +26° (c 0.05, MeOH); ESI-
MS m/z 716 (M+H)+ as C28H41N7O5S5; TOF-ESI-HRMS (M+H)+ calcd. for
C28H41N7O5S5: 716.1851, found: 716.1854; 1H NMR (400 MHz, CD3OD)
δ 0.75–0.86 (m, 3H), 1.15–1.26 (m, 4H), 1.42 (d, J = 6.8 Hz, 3H), 1.68–1.78
(m, 1H), 1.89–2.15 (m, 3H), 1.94 (s, 3H), 2.27 (s, 3H), 3.00 (s, 3H), 3.09
(dd, J = 8.2, 6.2 Hz, 1H), 3.24–3.31 (m, 1H), 3.50 (dd, J =10.2, 3.2 Hz, 1H),
3.72 (d, J = 14.3 Hz, 1H), 3.79 (br dd, J = 3.2, 1.0 Hz, 1H), 3.85 (d, J = 14.3 Hz,
1H), 4.01 (dd, J = 10.2, 5.5 Hz, 1H), 4.13–4.21 (m, 1H), 4.28–4.34 (m, 1H),
4.44 (dd, J =8.8, 4.6 Hz, 1H), 5.16 (d, J =5.5 Hz, 1H, 8.03 (s, 1H) and 8.69
(s, 1H).
1′-N-(tert-butoxycarbonyl)-4′-{3-(tert-butyldimethylsilyloxy)
propyl}-1′-demethyl-4′-depropyllincomycin (49)
Compound 11 (3.02, crude), 1-hydroxybenzotriazole (1.35 g, 10.01 mmol), N,
N′-dicyclohexylcarbodiimide (2.07 g, 10.01 mmol) and MTL (2.54 g,
10.01 mmol) in DMF (15.0 ml) were treated for 13 h according to the similar
procedure as described for the preparation of 19 to afford 49 (3.0 g, 62.5% in 3
steps from 8) as a colorless solid. ESI-MS m/z 623 (M+H)+ as C28H54N2O9SSi;
1H NMR (400 MHz, CD3OD) δ 0.06 (s, 6H), 0.90 (s, 9H), 1.15–1.27 (m, 3H),
1.37–1.64 (m, 4H), 1.44, 1.47 (s x 2, 9H), 1.74–1.91 (m, 1H), 2.06, 2.07 (s x 2,
3H), 2.09–2.18 (m, 1H), 2.30–2.45 (m, 1H), 2.94 (br t, J = 10.0 Hz, 1H),
3.53–3.72 (m, 4H), 3.74–3.93 (m, 1H), 3.98–4.17 (m, 3H), 4.24 (br dd, J = 8.9,
1.3 Hz, 1H), 4.27–4.46 (m, 1H) and 5.24 (d, J = 5.4 Hz, 1H).
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depropyl-4′-{03-(tert-
butyldimethylsilyloxy)propyl}- 2,3,4-tris-O-(trimethylsilyl)
lincomycin (50)
1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-propyllincomycin (46)
Compound 17 (1.55 g, 5.19 mmol), 1-hydroxybenzotriazole (1.05 g,
7.78 mmol), N,N′-dicyclohexylcarbodiimide (1.61 g, 7.78 mmol) and MTL Compound 49 (3.0 g, 4.82 mmol), trimethylchlorosilane (3.08 ml, 24.1 mmol)
(1.97 g, 7.78 mmol) in DMF (15.0 ml) were treated for 14 h according to the and hexamethyldisilazane (5.05 ml, 24.1 mmol) in pyridine (10 ml) were
similar procedure as described for the preparation of 18 to afford 46. The total treated for 20 min according to the similar procedure as described for the
amount of this compound was used without purification to synthesize 47. For
preparation of 23 and then the crude compound and 6 N acetic acid (1.45 ml)
the qualified analytical purpose, the above crude 46 was purified by column in methanol (27 ml) were treated for 80 min according to the similar procedure
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
15
as described for the preparation of 23 to afford 50 (3.02 g, 74.8% in two steps
C27H40N6O7S3; TOF-ESI-HRMS (M+H)+ calcd. for C27H40N6O7S3: 657.2199,
from 49) as a colorless solid. ESI-MS m/z 839 (M+H)+ as C37H78N2O9SSi4; 1H found: 657.2193; 1H NMR (400 MHz, CD3OD) δ 1.34–1.44 (m, 2H), 1.48–1.64
(m, 2H), 1.57 (d, J = 7.0 Hz, 3H), 1.76–1.88 (m, 1H), 2.01 (s, 3H), 2.04–2.13
(m, 2H), 2.34 (s, 6 H), 2.46 (t, J = 7.8 Hz, 2H), 2.56 (dd, J = 10.3, 7.8 Hz, 1H),
3.24 (dd, J = 10.3, 6.8 Hz, 1H), 3.56 (dd, J = 10.2, 3.3 Hz, 1H), 3.81 (dd, J = 9.3,
3.9 Hz, 1H), 3.83 (br dd, J = 3.3, 0.8 Hz, 1H), 4.10 (dd, J = 10.2, 5.6 Hz, 1H),
4.41 (br dd, J = 9.9, 0.8 Hz, 1H), 4.46 (dq, J = 7.0, 2.8 Hz, 1H), 4.62 (dd, J = 9.9,
2.8 Hz, 1H), 5.28 (d, J = 5.6 Hz, 1H), 7.75–7.87 (m, 3H) and 8.06–8.15
(m, 1H).
NMR (400 MHz, CDCl3) δ 0.04 (s, 6H), 0.07–0.20 (m, 27H), 0.89 (s, 9H),
1.05–1.22 (m, 3H), 1.35–1.90 (m, 5H), 1.48 (s, 9H), 2.07 (s, 3H), 2.11–3.25
(m, 3H), 3.44–3.66 (m, 4H), 3.70–3.89 (m, 1H), 3.91–4.18 (m, 3H), 4.19–4.42
(m, 2H) and 5.19 (br d, J = 5.6 Hz, 1H).
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-4′-depropyl-
4′-(3-hydroxypropyl)-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}
lincomycin (51)
7(S)-1′-demethyl-7-deoxy-4′-depropyl-4′-(3-methoxypropyl)-7-{5-
(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}lincomycin (54)
To a solution of compound 50 (2.87 g, 3.41 mmol) in THF (15 ml) at 0 °C
were added triphenylphosphine (1.34 g, 5.12 mmol), diethylazodicarboxylate
(932 μl, 5.12 mmol) and 5-(2-nitrophenyl)-1,3,4-thiadiazole-2-thiol (1.26 g,
5.29 mmol) and stirred at room temperature for 10 h. The solution was
substituted by toluene, purified by silica gel column chromatography
(hexane to hexane/ethyl acetate = 4/1) to obtain 1′-N-(tert-butoxycarbonyl)-
4′-{3-(tert-butyldimethylsilyloxy)propyl}-1′-demethyl-7-deoxy-4′-depropyl-7-
{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}-2,3,4-tris-O-(trimethylsilyl)linco-
mycin (2.62 g, crude). To this crude compound (2.62 g) was added 1 M THF
solution of tetra-n-butyl ammonium fluoride (14.8 ml, 14.8 mmol) and acetic
acid (0.848 ml, 14.8 mmol) and stirred at room temperature for 5 h. The
mixture was diluted with brine and ethyl acetate, extracted with ethyl acetate,
and then the organic phase was dried over Na2SO4, filtrated and concentrated
under reduced pressure. The resulting residue was purified by silica gel column
chromatography (hexane/ethyl acetate= 1/1 to ethyl acetate only to ethyl
acetate/MeOH= 10/1) to obtain the title compound (1.74 g with unseparable
impurity (96% in two steps as reference yield)). FAB-MS m/z 752 (M+Na)+ as
C30H43N5O10S3.
Compound 24 (266.0 mg, 0.36 mmol), triphenylphosphine (142.0 mg,
0.54 mmol), diethylazodicarboxylate (98 μl, 0.54 mmol) and 5-(2-nitrophe-
nyl)-1,3,4-thiadiazole-2-thiol (132.0 mg, 0.56 mmol) in THF (2 ml) were
treated for 18 h according to the similar procedure as described for the
preparation of 31 to afford 7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-
deoxy-4′-depropyl-4′-(3-methoxypropyl)-7-{5-(2-nitrophenyl)-1,3,4-thiadia-
zol-2-ylthio}-2,3,4-tris-O-(trimethylsilyl)lincomycin (325.0 mg as crude). To
this crude compound (325.0 mg) was added 2,2,2-trifluoroacetic acid (1 ml) at
0 °C and stirred at room temperature for 15 min. The solution was concen-
trated under reduced pressure. The resulting residue was purified by preparative
TLC (CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2) to obtain the title compound
24
(112.0 mg, 48.3% in two steps from 24) as a colorless solid. [α]D +82.6°
(c 0.45, MeOH); ESI-MS m/z 644 (M+H)+ as C26H37N5O8S3; TOF-ESI-HRMS
(M+H)+ calcd. for C26H37N5O8S3: 644.1883, found: 644.1880; 1H NMR
(400 MHz,CD3OD)
δ 1.40–1.52 (m, 2H), 1.54–1.65 (m, 2H), 1.57
(d, J = 6.9 Hz, 3H), 1.89–1.97 (m, 1H), 2.01 (s, 3H), 2.09–2.23 (m, 2H), 2.68
(dd, J = 10.7, 8.0 Hz, 1H), 3.30 (s, 3H), 3.32–3.36 (m, 1H), 3.39 (t, J =6.2, 2H),
3.57 (dd, J = 10.2, 3.2 Hz, 1H), 3.85 (br dd, J = 3.2, 0.8 Hz, 1H), 4.02 (dd,
J = 9.1, 4.1 Hz, 1H), 4.11 (dd, J = 10.2, 5.6 Hz, 1H), 4.42 (br dd, J = 10.0,
0.8 Hz, 1H), 4.47 (dq, J = 6.9, 2.7 Hz, 1H), 4.66 (dd, J = 10.0, 2.7 Hz, 1H), 5.28
(d, J = 5.6 Hz, 1H), 7.76–7.87 (m, 3H) and 8.06–8.14 (m, 1H).
7(S)-4′-(3-aminopropyl)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-
deoxy-4′-depropyl-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}
lincomycin (52)
To a solution of compound 51 (500 mg, 0.685 mmol), sodium azide (223 mg,
3.43 mmol) and triphenylphosphine (359.3 mg, 1.37 mmol) in DMF (7 ml)
was added tetrabromomethane (454.3 mg, 1.37 mmol) and stirred at 50 °C for
2 h. The mixture was diluted with brine and ethyl acetate, extracted with ethyl
acetate and then the organic phase was dried over Na2SO4, filtrated and
concentrated under reduced pressure. The resulting residue was purified by
silica gel column chromatography (chloroform/MeOH=10/1) to obtain
7(S)-4′-(3-azidopropyl)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-4′-
7(S)-4′-i-butyl-1′-demethyl-7-deoxy-4′-depropyl-7-(5-(2-
nitrophenyl)-1,3,4-thiadiazol-2-yl)thiolincomycin (55)
Compound 25 (204.0 mg, 0.28 mmol), triphenylphosphine (109.1 mg,
0.42 mmol), diethylazodicarboxylate (75.8 μl, 0.42 mmol) and 5-(2-nitrophe-
nyl)-1,3,4-thiadiazole-2-thiol (103.0 mg, 0.43 mmol) in THF (2 ml) were
treated for 14.5 h according to the similar procedure as described for the
preparation of 31 to afford 7(S)-1′-N-(tert-butoxycarbonyl)-4′-i-butyl-1′-
demethyl-7-deoxy-4′-depropyl-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}-
2,3,4-tris-O-(trimethylsilyl)lincomycin (170.0 mg as crude). To this crude
compound (170.0 mg) was added 2,2,2-trifluoroacetic acid (1 ml) at 0 °C and
stirred at room temperature for 30 min. The solution was concentrated under
reduced pressure. The resulting residue was purified by preparative TLC
(CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2) to obtain the title compound
depropyl-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}lincomycin
(468 mg
with unseparable impurity (91% as reference yield)). To a solution of this
crude compound (239 mg, 0.317 mmol) in THF (3 ml) was added triphenyl-
phosphine (249.0 mg, 0.95 mmol), stirred at room temperature for 1 h, and
then H2O was added and stirred at 50 °C for 2 h. The mixture was diluted with
brine, ethyl acetate and 1 N HCl (400 μl), washed with ethyl acetate and then
the aqueous phase was added to the saturated aqueous NaHCO3, extracted with
CHCl3, dried over Na2SO4, filtrated and concentrated under reduced pressure
to obtain the title compound (229 mg with unseparable impurity (99% as
reference yield)).
24
(39.0 mg, 22.5% in two steps from 25) as a colorless solid. [α]D +85.8°
(c 0.54, MeOH); ESI-MS m/z 628 (M+H)+ as C26H37N5O7S3; TOF-ESI-HRMS
(M+H)+ calcd. for C26H37N5O7S3: 628.1933, found: 628.1936; 1H NMR
(400 MHz, CD3OD) δ 0.90 (d, J = 5.3 Hz, 3H), 0.91 (d, J =5.4 Hz, 3H),
1.23–1.34 (m, 2H), 1.53–1.64 (m, 1H), 1.57 (d, J = 6.8 Hz, 3H), 1.81–1.92
(m, 1H), 2.00 (s, 3H), 2.04–2.15 (m, 1H), 2.15–2.27 (m, 1H), 2.58 (dd, J = 10.4,
8.7 Hz, 1H), 3.26–3.30 (m, 1H), 3.56 (dd, J = 10.2, 3.2 Hz, 1H), 3.84 (br dd,
J = 3.2, 0.8 Hz, 1H), 3.92 (dd, J = 9.2, 4.3 Hz, 1H), 4.10 (dd, J =10.2, 5.6 Hz,
1H), 4.41 (br dd, J = 10.0, 0.8 Hz, 1H), 4.47 (dq, J = 6.8, 2.8 Hz, 1H), 4.65
(dd, J = 10.0, 2.8 Hz, 1H), 5.28 (d, J = 5.6 Hz, 1H), 7.76–7.87 (m, 3H) and
8.08–8.13 (m, 1H).
7(S)-1′-demethyl-7-deoxy-4′-depropyl-4′-(3-dimethylaminopropyl)-
7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}lincomycin (53)
Compound 52 (69.0 mg, 0.093 mmol), 36% aqueous formaldehyde (23.1 μl,
0.28 mmol), AcOH (79.5 μl, 1.39 mmol) and NaBH(OAc)3 (294.3 mg,
1.39 mmol) in MeOH (1 ml) were treated at room temperature for 20 min
according to the similar procedure as described for the preparation of 38 to
afford 7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-4′-depropyl-4′-(3-
dimethylaminopropyl)-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}lincomy-
cin (75.0 mg, crude). To this crude compound (75.0 mg) was added 2,2,2-
trifluoroacetic acid (1 ml) at 0 °C and stirred at room temperature for 30 min.
The solution was concentrated under reduced pressure. The resulting residue
was purified by preparative TLC (CHCl3/MeOH/28% aq. NH4OH=9/4/0.4) to
7(S)-1′-demethyl-7-deoxy-4′-depropyl-7-{5-(2-nitrophenyl)-1,3,4-
thiadiazol-2-ylthio}-4′-n-pentyllincomycin (56)
Compound 26 (400 mg, 0.54 mmol), triphenylphosphine (213.5 mg,
0.81 mmol), diethylazodicarboxylate (150 μl, 0.81 mmol) and 5-(2-nitrophe-
nyl)-1,3,4-thiadiazole-2-thiol (201.4 mg, 0.84 mmol) in THF (4 ml) were
obtain the title compound (35.0 mg, 57.6% in two steps from 52) as a colorless treated for 24 h according to the similar procedure as described for the
+83.7° (c 0.45, MeOH); ESI-MS m/z 657 (M+H)+ as preparation of 31 to afford 7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-
25
solid. [α]D
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
16
deoxy-4′-depropyl-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-ylthio}-4′-n-pentyl-
2,3,4-tris-O-(trimethylsilyl)lincomycin (374.0 mg as crude). To this crude
compound (374 mg) was added 2,2,2-trifluoroacetic acid (1 ml) at 0 °C and
stirred at room temperature for 30 min. The solution was concentrated under
reduced pressure. The resulting residue was purified by preparative TLC
(CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2) to obtain the title compound
δ 0.84–0.93 (m, 3H), 1.19–1.39 (m, 8H), 1.54 (d, J = 6.9 Hz, 3H), 1.80–1.92
(m, 1H), 2.02 (s, 3H), 1.96–2.21 (m, 3H), 2.40 (s, 3H), 3.06–3.14 (m, 1H), 3.12
(s, 3H), 3.21 (dd, J = 7.9, 5.5 Hz, 1H), 3.61 (dd, J = 10.2, 3.1 Hz, 1H), 3.84
(dd, J = 3.1, 0.6 Hz, 1H), 4.12 (dd, J = 10.2, 5.6 Hz, 1H), 4.28 (dq, J = 6.9,
2.9 Hz, 1H), 4.43–4.44 (m, 1H), 4.59 (dd, J =10.0, 2.9 Hz, 1H), 5.28
(d, J = 5.6 Hz, 1H) and 8.14 (s, 1H).
25
(72.6 mg, 20.9% in two steps from 26) as a colorless solid. [α]D +34.3°
(c 0.10, MeOH); ESI-MS m/z 642 (M+H)+ as C27H39N5O7S3; TOF-ESI-HRMS
(M+H)+ calcd. for C27H39N5O7S3: 642.2090, found: 642.2083; 1H NMR
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-7-{4-
(methoxycarbonyl)phenylthio}lincomycin (60)
(400 MHz, CD3OD)
δ 0.80–0.95 (m, 3H), 1.21–1.43 (m, 8H), 1.57
(d, J = 7.0 Hz, 3H), 1.81–1.95 (m, 1H), 2.02–2.14 (m, 2H), 2.09 (s, 3H), 2.62
(dd, J = 10.4, 7.9 Hz, 1H), 3.27 (dd, J = 10.5, 6.8 Hz, 1H), 3.61 (dd, J = 10.2,
3.2 Hz, 1H), 3.83 (br dd, J = 3.2, 0.9 Hz, 1H), 3.91 (dd, J = 9.1, 4.2 Hz, 1H),
4.14 (dd, J = 10.2, 5.6 Hz, 1H), 4.34–4.40 (m, 1H), 4.42 (dq, J = 7.0, 2.9 Hz,
1H), 4.57 (dd, J = 10.0, 2.9 Hz, 1H), 5.31 (d, J = 5.6 Hz, 1H), 7.71–7.87
(m, 3H) and 8.07–8.14 (m, 1H).
To a solution of compound 23 (5.0 g, 7.05 mmol) in CHCl3 (22 ml) were
added Et3N (2.45 ml, 17.6 mmol), methanesulfonyl chloride (1.1 ml,
14.1 mmol) and stirred at room temperature for 30 min. The mixture was
added to saturated aqueous NaHCO3, extracted with CHCl3, dried over Na2SO4
and concentrated under reduced pressure. To a solution of crude compound in
DMF (50 ml) were added K2CO3 (2.92 g, 21.2 mmol) and methyl
4-mercaptobenzoate (2.37 g, 14.1 mmol), stirred at 100 °C for 6 h and
concentrated under reduced pressure. The resulting residue in MeOH
(50 ml) was added to 1 N HCl (100 ml) and stirred at room temperature for
20 min. The mixture was added to the saturated aqueous NaHCO3, then
extracted with ethyl acetate, dried over Na2SO4, filtrated and concentrated
under reduced pressure. The resulting residue was purified by silica gel column
chromatography (CHCl3/MeOH/28% aq. NH4OH= 20/1/0.1) to obtain the
title compound as a colorless solid (1.25 g, 27.6% in three steps from 23).
ESI-MS (m/z) 643 (M+H)+ as C30H46N2O9S2; 1H NMR (400 MHz, CD3OD)
δ 0.86–1.00 (m, 3H), 1.25–1.65 (m, 16H), 1.45, 1.48 (s x 2, 9H), 1.73–1.99
(m, 1H), 1.79, 1.85 (s x 2, 3H), 2.07–2.20 (m, 1H), 2.22–2.42 (m, 1H),
2.92–3.01 (m, 1H), 3.53–3.61 (m, 1H), 3.63–3.74 (m, 1H), 3.88 (s, 3H),
3.90–4.15 (m, 3H), 4.28–4.50 (m, 2H), 4.54–4.68 (m, 1H), 5.24 (d, J = 5.4 Hz,
1H), 7.39–7.46 (m, 2H) and 7.89–7.96 (m, 2H).
7(S)-7-deoxy-4′-depropyl-7-{5-(2-nitrophenyl)-1,3,4-thiadiazol-2-
ylthio}-4′-n-pentyllincomycin (57)
Compound 56 (56.1 mg, 0.087 mmol), 36% aqueous formaldehyde (22 μl,
0.26 mmol), AcOH (30 μl, 0.52 mmol) and NaBH(OAc)3 (55.5 mg,
0.26 mmol) in MeOH (0.6 ml) were treated at room temperature for 1 h
according to the similar procedure as described for the preparation of 38 to
afford 57 (49.1 mg, 85.7%) as a colorless solid. [α]D25 +91.6° (c 1.16, MeOH);
ESI-MS m/z 656 (M+H)+ as C28H41N5O7S3; TOF-ESI-HRMS (M+H)+ calcd.
for C28H41N5O7S3: 656.2246, found: 656.2238; 1H NMR (400 MHz, CD3OD)
δ 0.83–0.92 (m, 3H), 1.21–1.42 (m, 8H), 1.57 (d, J = 7.0 Hz, 3H), 1.78–1.91
(m, 1H), 1.96–2.10 (m, 2H), 2.01 (s, 3H), 2.12–2.27 (m, 1H), 2.39 (s, 3H), 3.02
(dd, J = 10.5, 5.1 Hz, 1H), 3.23–3.29 (m, 1H), 3.57 (dd, J =10.2, 3.2 Hz, 1H),
3.81 (dd, J = 3.2, 0.7 Hz, 1H), 4.11 (dd, J = 10.2, 5.6 Hz, 1H), 4.39–4.49
(m, 1H), 4.60 (dd, J = 9.8, 3.2 Hz, 1H), 5.27 (d, J = 5.6, 1H), 7.75–7.85 (m, 3H)
and 8.06–8.11 (m, 1H).
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-4′-depropyl-7-
(4-(methoxycarbonyl)phenyl)thio-4′-{(E)-pent-2-enyl}lincomycin (61)
Compound 27 (1.45 g, 1.97 mmol), Et3N (0.69 ml, 4.93 mmol) and methane-
sulfonyl chloride (0.31 ml, 3.93 mmol) in CHCl3 (6.1 ml) were treated at room
temperature for 30 min according to the similar procedure as described for the
preparation of 60 to afford 1′-N-(tert-butoxycarbonyl)-1′-demethyl-4′-depro-
pyl-7-O-methanesulfonyl-4′-{(E)-pent-2-enyl}-2,3,4-tris-O-(trimethylsilyl)lin-
comycin. To a solution of crude compound were added K2CO3 (1.23 g,
8.87 mmol) and methyl 4-mercaptobenzoate (0.99 g, 5.91 mmol) in DMF
(13.8 ml) and treated at 80 °C for 1 h. The resulting residue and 1 N HCl
(14 ml) in MeOH (14 ml) were treated at room temperature for 20 min
according to the similar procedure as described for the preparation of 60 to
afford 61 (1.21 g, 92% in three steps from 27) as a colorless solid. EI-MS m/z
668 (M)+ as C32H48N2O9S2; 1H NMR (400 MHz, CD3OD) δ 0.95 (t, J = 7.4 Hz,
3H), 1.33–1.44 (m, 3H), 1.45, 1.48 (s x 2, 9H), 1.80, 1.85 (s x 2, 3H), 1.87–2.17
(m, 6H), 2.26–2.40 (m, 1H), 3.01–3.09 (m, 1H), 3.51–3.67 (m, 2H), 3.88
(s, 3H), 3.91–4.12 (m, 3H), 4.27–4.46 (m, 2H), 4.53–4.64 (m, 1H), 5.24
(d, J = 5.6 Hz, 1H), 5.31–5.45 (m, 1H), 5.47–5.59 (m, 1H), 7.36–7.44 (m, 2H)
and 7.86–7.95 (m, 2H).
7(S)-1′-demethyl-7-deoxy-4′-depropyl-7-[5-{5-(methylamino)
thiazol-4-yl}-1,3,4-thiadiazol-2-ylthio]-4′-n-pentyllincomycin (58)
Compound 26 (400 mg, 0.54 mmol), triphenylphosphine (213.5 mg,
0.81 mmol), diethylazodicarboxylate (150 μl, 0.81 mmol) and 5-{5-(methyla-
mino)thiazol-4-yl}-1,3,4-thiadiazole-2-thiol (193.9 mg, 0.84 mmol) in THF
(4 ml) were treated for 24 h according to the similar procedure as described
for the preparation of 31 to afford 7(S)-1′-N-(tert-butoxycarbonyl)-1′-
demethyl-7-deoxy-4′-depropyl-7-[5-{5-(methylamino)thiazol-4-yl}-1,3,4-thia-
diazol-2-ylthio]-4′-n-pentyl-2,3,4-tris-O-(trimethylsilyl)lincomycin (109.8 mg,
21.3%). To the compound (109.8 mg, 0.12 mmol) was added 2,2,2-trifluor-
oacetic acid (1 ml) at 0 °C and stirred at room temperature for 30 min. The
solution was concentrated under reduced pressure. The resulting residue was
purified by preparative TLC (CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2) to
25
obtain the title compound (59.0 mg, 80.6%) as a colorless solid. [α]D +48.5°
(c 0.22, MeOH); ESI-MS m/z 633 (M+H)+ as C25H40N6O5S4; TOF-ESI-HRMS
(M+H)+ calcd. for C25H40N6O5S4: 633.2021, found: 633.2021; 1H NMR
(400 MHz, CD3OD)
δ 0.83–0.94 (m, 3H), 1.21–1.43 (m, 8H), 1.50
(d, J = 6.8 Hz, 3H), 1.80–1.91 (m, 1H), 2.02 (s, 3H), 2.02–2.13 (m, 2H), 2.59
(dd, J = 10.5, 8.0 Hz, 1H), 3.12 (s, 3H), 3.24–3.30 (m, 1H), 3.58 (dd, J = 10.2,
3.2 Hz, 1H), 3.85 (br dd, J = 3.2, 0.7 Hz, 1H), 3.93 (dd, J = 9.1, 4.0 Hz, 1H),
4.11 (dd, J = 10.2, 5.6 Hz, 1H), 4.29 (dq, J = 6.8, 2.7 Hz, 1H), 4.37–4.44
(m, 1H), 4.61 (dd, J = 10.0, 2.7 Hz, 1H), 5.28 (d, J = 5.6 Hz, 1H) and 8.13
(s, 1H).
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-4′-depropyl-
7-{4-(methoxycarbonyl)phenylthio}-4′-n-pentyllincomycin (62)
Compound 61 (105 mg, 0.16 mmol) and Pd/C (100 mg) in MeOH (2 ml) were
treated for 15 h according to the similar procedure as described for the
preparation of 7 to afford 62 (97 mg, 92.1%) as a colorless solid. ESI-MS m/z
671 (M+H)+ as C32H50N2O9S2; 1H NMR (400 MHz, CD3OD) δ 0.18–0.92
(m, 3H), 1.15–1.52 (m, 11H), 1.44, 1.47 (s x 2, 9H), 1.71–1.93 (m, 1H), 1.78,
1.83 (s x 2, 3H), 2.05–2.18 (m, 1H), 2.20–2.36 (m, 1H), 2.95 (br t, J = 10.0 Hz,
1H), 3.52–3.61 (m, 1H), 3.61–3.73 (m, 1H), 3.87 (s, 3H), 3.91–4.03 (m, 2H),
4.03–4.15 (m, 1H), 4.28–4.47 (m, 2H), 4.53–4.65 (m, 1H), 5.25 (d, J = 5.6 Hz,
7(S)-7-deoxy-4′-depropyl-7-[5-{5-(methylamino)thiazol-4-yl}-1,3,4-
thiadiazol-2-ylthio]-4′-n-pentyllincomycin (59)
Compound 58 (35.8 mg, 0.057 mmol), 36% aqueous formaldehyde (14 μl,
0.17 mmol), AcOH (20 μl, 0.34 mmol) and NaBH(OAc)3 (36.0 mg,
0.17 mmol) in MeOH (0.5 ml) were treated at room temperature for 1 h
according to the similar procedure as described for the preparation of 38 to
afford 59 (29.4 mg, 80.3%) as an off-white solid. [α]D25 +64.5° (c 0.30, MeOH);
ESI-MS m/z 647 (M+H)+ as C26H42N6O5S4; TOF-ESI-HRMS (M+H)+ calcd.
for C26H42N6O5S4: 647.2178, found: 647.2176; 1H NMR (400 MHz, CD3OD) 1H), 7.35–7.47 (m, 2H) and 7.85–7.95 (m, 2H).
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
17
7(S)-1′-N-(tert-butoxycarbonyl)-7-{4-(carboxyl)phenylthio}-1′-
demethyl-7-deoxylincomycin (63)
(dd, J =10.2, 5.6 Hz, 1H), 4.37 (br dd, J = 9.9, 0.8 Hz, 1H), 4.54 (dd, J = 9.9,
2.7 Hz, 1H), 5.25 (d, J = 5.6 Hz, 1H), 7.35–7.41 (m, 2H) and 7.43–7.49
(m, 2H).
To a solution of compound 60 (761 mg, 1.18 mmol) in MeOH (20 ml) was
added 1 N NaOH (1.78 ml, 1.78 mmol) and stirred at room temperature for
7 days. The mixture was added 1 N HCl (pH=3), extracted with CHCl3, dried
over Na2SO4 and concentrated under reduced pressure to obtain the title
compound (705 mg, 94.7%) as an off-white solid. ESI-MS m/z 629 (M+H)+ as
C29H44N2O9S2.
7(S)-1′-demethyl-7-deoxy-4′-depropyl-7-{4-(morpholinocarbonyl)
phenylthio}-4′-n-pentyllincomycin (68)
Compound 66 (82.0 mg, 0.11 mmol) and 2,2,2-trifluoroacetic acid (1 ml) were
treated at − 15 to 0 °C for 40 min according to the similar procedure as
described for the preparation of 67 to afford 68 (57.0 mg, 80.6%) as a colorless
7(S)-1′-N-(tert-butoxycarbonyl)-7-{4-(carboxyl)phenylthio}-1′-
demethyl-7-deoxy-4′-depropyl-4′-n-pentyllincomycin (64)
+74.0° (c 0.51, MeOH); ESI-MS m/z 626 (M+H)+ as
26
solid. [α]D
C30H47N3O7S2; TOF-ESI-HRMS (M+H)+ calcd. for C30H47N3O7S2: 626.2934,
found: 626.2924; 1H NMR (400 MHz, CD3OD) δ 0.83–0.93 (m, 3H), 1.23–1.44
(m, 8H), 1.33 (d, J = 6.9 Hz, 3H), 1.77–1.88 (m, 1H), 1.90 (s, 3H), 1.99–2.15
(m, 2H), 2.61 (dd, J =10.4, 8.2 Hz, 1H), 3.24 (dd, J = 10.4, 7.0 Hz, 1H),
3.36–3.57 (m, 2H), 3.56 (dd, J = 10.2, 3.2 Hz, 1H), 3.57–3.84 (m, 6H), 3.78
(br dd, J = 3.2, 0.7 Hz, 1H), 3.88 (dd, J = 9.5, 4.0 Hz, 1H), 3.95 (dq, J = 6.9,
2.6 Hz, 1H), 4.08 (dd, J = 10.2, 5.6 Hz, 1H), 4.36 (br dd, J = 9.9, 0.7 Hz, 1H),
4.53 (dd, J = 9.9, 2.6 Hz, 1H), 5.25 (d, J = 5.6 Hz, 1H), 7.34–7.41 (m, 2H) and
7.42–7.50 (m, 2H).
Compound 62 (97 mg, 0.15 mmol) and 1 N NaOH (0.55 ml) in MeOH
(1.1 ml) were treated for 18 h according to the similar procedure as described
for the preparation of 63 to afford 64 (91.3 mg, 96.1%) as a colorless solid.
FAB-MS m/z 695 (M+K)+ as C31H48N2O9S2; 1H NMR (400 MHz, CD3OD)
δ 0.82–0.92 (m, 3H), 1.20–1.45 (m, 11H), 1.46, 1.48 (s x 2, 9H), 1.75–1.95
(m, 1H), 1.81, 1.86 (s x 2, 3H), 2.09–2.19 (m, 1H), 2.21–2.37 (m, 1H),
2.90–3.02 (m, 1H), 3.54–3.62 (m, 1H), 3.63–3.75 (m, 1H), 3.90–4.05 (m, 2H),
4.05–4.15 (m, 1H), 4.30–4.49 (m, 2H), 4.53–4.67 (m, 1H), 5.27 (d, J = 5.6 Hz,
1H), 7.37–7.45 (m, 2H) and 7.89–7.97 (m, 2H).
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-7-{4-
(morpholinocarbonyl)phenylthio}lincomycin (65)
7(S)-7-deoxy-4′-depropyl-7-{4-(morpholinocarbonyl)phenylthio}-
4′-n-pentyllincomycin (69)
To a solution of compound 63 (200 mg, 0.32 mmol), 1-hydroxybenzotriazole
(64.5 mg, 0.48 mmol) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide
HCl salt (91.5 mg, 0.48 mmol) in DMF (2 ml) was added to morpholine
(42 μl, 0.48 mmol) and stirred at room temperature for 22 h. The mixture was
added to saturated aqueous NaHCO3, extracted with ethyl acetate, dried over
Na2SO4 and concentrated under reduced pressure. The resulting residue was
purified by preparative TLC (CHCl3/MeOH/28% aq. NH4OH= 9/2/0.2) to
obtain the title compound (215.0 mg, 96.8%) as a colorless solid. ESI-MS m/z
698 (M+H)+ as C33H51N3O9S2; 1H NMR (400 MHz, CD3OD) δ 0.86–0.97
(m, 3H), 1.25–1.45 (m, 7H), 1.46, 1.48 (s x 2, 9H), 1.78–1.95 (m, 1H), 1.88,
1.91 (s x 2, 3H), 2.06–2.18 (m, 1H), 2.24–2.40 (m, 1H), 2.92–2.99 (m, 1H),
3.37–3.85 (m, 10H), 3.88–3.99 (m, 2H), 4.05–4.14 (m, 1H), 4.30–4.45 (m, 2H),
4.52–4.63 (m, 1H), 5.26 (d, J = 5.6 Hz, 1H), 7.35–7.42 (m, 2H) and 7.43–7.48
(m, 2H).
Compound 68 (31.0 mg, 0.050 mmol), 36% aqueous formaldehyde (12 μl,
0.15 mmol), AcOH (17 μl, 0.30 mmol) and NaBH(OAc)3 (31.6 mg,
0.15 mmol) in MeOH (0.5 ml) were treated at room temperature for 30 min
according to the similar procedure as described for the preparation of 38 to
26
afford 69 (31.0 mg, 97.8%) as a colorless solid. [α]D +68° (c 0.12, MeOH);
ESI-MS m/z 640 (M+H)+ as C31H49N3O7S2; TOF-ESI-HRMS (M+H)+ calcd.
for C31H49N3O7S2: 640.3090, found: 640.3080; 1H NMR (400 MHz, CD3OD)
δ 0.85–0.94 (m, 3H), 1.23–1.43 (m, 8H), 1.35 (d, J = 6.8 Hz, 3H), 1.81–1.92
(m, 1H), 1.91 (s, 3H), 2.03 (ddd, J = 13.0, 7.8, 5.0 Hz, 1H), 2.08–2.25 (m, 2H),
2.44 (s, 3H), 3.06 (dd, J = 10.5, 4.9 Hz, 1H), 3.25–3.30 (m, 1H), 3.38–3.84
(m, 9H), 3.58 (dd, J = 10.2, 3.2 Hz, 1H), 3.97 (dq, J = 6.8, 2.6 Hz, 1H), 4.10
(dd, J = 10.2, 5.6 Hz, 1H), 4.33–4.39 (m, 1H), 4.51 (dd, J = 9.7, 2.6 Hz, 1H),
5.26 (d, J = 5.6 Hz, 1H), 7.37–7.42 (m, 2H) and 7.45–7.50 (m, 2H).
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-4′-depropyl-
7-{4-(morpholinocarbonyl)phenylthio}-4′-n-pentyllincomycin (66)
Compound 64 (91.3 mg, 0.14 mmol), 1-hydroxybenzotriazole (28.1 mg,
0.21 mmol) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide HCl salt
(40.0 mg, 0.21 mmol) and morpholine (18 μl, 0.21 mmol) in DMF (1 ml)
were treated for 62 h according to the similar procedure as described for the
preparation of 65 to afford 66 (82.0 mg, 81.3%) as a colorless solid. FAB-MS
m/z 726 (M+H)+ as C35H55N3O9S2; 1H NMR (400 MHz, CD3OD) δ 0.82–0.94
(m, 3H), 1.21–1.42 (m, 11H), 1.46, 1.48 (s x 2, 9H), 1.77–1.95 (m, 1H), 1.87,
1.91 (s x 2, 3H), 2.08–2.18 (m, 1H), 2.20–2.38 (m, 1H), 2.90–3.01 (m, 1H),
3.38–3.84 (m, 10H), 3.87–4.01 (m, 2H), 4.05–4.14 (m, 1H), 4.29–4.46 (m, 2H),
4.52–4.63 (m, 1H), 5.26 (d, J = 5.6 Hz, 1H), 7.35–7.42 (m, 2H) and 7.42–7.48
(m, 2H).
7(S)-7-acetylthio-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-
deoxylincomycin (70)
To a solution of compound 23 (500.3 mg, 0.71 mmol) in CH2Cl2 (10 ml) were
added Et3N (0.25 ml, 1.77 mmol) and methanesulfonyl chloride (0.11 ml,
1.39 mmol), stirred at 0 °C for 1 h. The mixture was added to saturated
aqueous NH4Cl, extracted with ethyl acetate, washed with 25% brine, dried
over Na2SO4 and concentrated under reduced pressure. To a solution of this
crude compound in DMF (8 ml) was added AcSK (501.7 mg, 4.39 mmol),
stirred at 60˚C for 10 h. The mixture was added to the saturated aqueous
NaHCO3, then extracted with ethyl acetate, dried over Na2SO4, filtrated and
concentrated under reduced pressure. The resulting residue was purified by
silica gel column chromatography (hexane/ethyl acetate= 10/1 to 2/1) to
obtain 7(S)-7-acetylthio-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-2,3,4-
tris-O-(trimethylsilyl)lincomycin as a colorless solid (217.8 mg, 40.2% in two
steps from 23). To a solution of this intermediate in MeOH (2.2 ml) was added
1 N HCl (2.2 ml) and stirred at room temperature for 1 h. The mixture was
added to saturated aqueous NaHCO3, extracted with ethyl acetate, dried over
Na2SO4 and concentrated under reduced pressure. The resulting residue was
purified by silica gel column chromatography (chloroform/MeOH =40/1) to
obtain the title compound (137 mg, 87.6%) as a colorless solid. ESI-MS m/z 551
7(S)-1′-demethyl-7-deoxy-7-{4-(morpholinocarbonyl)phenylthio}
lincomycin (67)
To the compound 65 (215 mg, 0.32 mmol) was added 2,2,2-trifluoroacetic acid
(2 ml) at 0 °C and stirred for 40 min. The solution was concentrated under
reduced pressure. The resulting residue was purified by preparative TLC
(CHCl3/MeOH/28% aq. NH4OH=9/2/0.2) to obtain the title compound
25
(104.0 mg, 56.5%) as a colorless solid. [α]D +70.5° (c 0.42, MeOH); ESI-
(M+H)+ as C24H42N2O8S2; 1H NMR (400 MHz, CD3OD)
δ 0.86–0.98
MS m/z 598 (M+H)+ as C28H43N3O7S2; TOF-ESI-HRMS (M+H)+ calcd. for
C28H43N3O7S2: 598.2621, found: 598.2623; 1H NMR (400 MHz, CD3OD)
δ 0.88–0.97 (m, 3H), 1.30–1.44 (m, 4H), 1.33 (d, J = 7.0 Hz, 3H), 1.80–1.93
(m, 1H), 1.90 (s, 3H), 2.05–2.18 (m, 2H), 2.65 (dd, J = 10.4, 8.2 Hz, 1H),
3.26–3.32 (m, 1H), 3.35–3.56 (m, 2H), 3.56 (dd, J = 10.2, 3.3 Hz, 1H),
(m, 3H), 1.26–1.41 (m, 7H), 1.46 (s, 9H), 1.76–1.96 (m, 1H), 2.01, 2.03
(s, 3H), 1.95–2.17 (m, 1H), 2.20–2.38 (m, 1H), 2.32 (s, 3H), 2.95 (t, J =9.8 Hz,
1H), 3.51 (dd, J = 10.2, 3.3 Hz, 1H), 3.66 (dd, J = 10.0, 7.6 Hz, 1H), 3.81–4.01
(m, 2H), 4.01–4.12 (m, 1H), 4.13–4.37 (m, 2H), 4.41–4.50 (m, 1H) and 5.21
3.52–3.85 (m, 6H), 3.79 (br dd, J = 3.3, 0.8 Hz, 1 ), 3.90–3.98 (m, 2H), 4.08 (d, J =5.5 Hz, 1H).
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
Y Wakiyama et al
18
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-7-
mercaptolincomycin (71)
(d, J = 9.6 Hz, 1H), 4.54–4.67 (m, 1H), 5.28 (d, J =5.5 Hz, 1H), 7.50–7.59
(m, 2H), 7.65–7.73 (m, 2H), 9.07 (s, 2H), 9.13 (s, 1H).
To a solution of compound 70 (137 mg, 0.25 mmol) in MeOH (1.5 ml) was
added sodium methoxide (43.2 mg, 0.76 mmol) and stirred at room tempera- 7(S)-1′-demethyl-7-deoxy-7-{4-(pyrimidin-5-yl)phenylthio}
ture for 1.5 h. The mixture was diluted with 8% aqueous NaHCO3, extracted
with ethyl acetate, dried over Na2SO4 and concentrated under reduced pressure.
The resulting residue was purified by silica gel column chromatography
(CHCl3/CH3OH= 40/1 to 10/1) to obtain the title compound (120.3 mg,
95.1%) as a colorless solid. FAB-MS m/z 509 (M+H)+ as C22H40N2O7S2; 1H
NMR (400 MHz, CD3OD) δ 0.87–0.99 (m, 3H), 1.23–1.42 (m, 7H), 1.47
(s, 9H), 1.80–1.98 (m, 1H), 2.05–2.15 (m, 1H), 2.15 (s, 3H), 2.20–2.39
(m, 1H), 2.97 (br t, J = 9.6 Hz, 1H), 3.39–3.58 (m, 1H), 3.54 (dd, J = 10.2,
3.0 Hz, 1H), 3.66 (dd, J = 10.2, 7.4 Hz, 1H), 3.80–3.90 (m, 1H), 4.02–4.18
(m, 2H), 4.26–4.46 (m, 2H) and 5.25 (d, J = 5.5 Hz, 1H).
lincomycin (75)
Compound 74 (117.9 mg, 0.18 mmol) and 2,2,2-trifluoroacetic acid (0.27 ml)
in CH2Cl2 (2.5 ml) were treated at − 20 °C for 20 min, and then treated room
temperature for 5 h according to the similar procedure as described for the
25
preparation of 73 to afford 75 (82.2 mg, 82.1%) as a colorless solid. [α]D
+91.7° (c 0.33, MeOH); ESI-MS m/z 563 (M+H)+ as C27H38N4O5S2; TOF-ESI-
HRMS (M+H)+ calcd. for C27H38N4O5S2: 563.2362, found: 563.2356; 1H NMR
(400 MHz, CD3OD) δ 0.78–0.88 (m, 3H), 1.20–1.32 (m, 4H), 1.25 (d,
J = 6.9 Hz, 3H), 1.68–1.78 (m, 1H), 1.86 (s, 3H), 1.92–2.05 (m, 2H), 2.55
(dd, J = 10.2, 8.0 Hz, 1H), 3.12 (dd, J = 10.2, 6.7 Hz, 1H), 3.48 (dd, J = 10.2,
3.3 Hz, 1H), 3.69 (br dd, J = 3.3, 0.7 Hz, 1H), 3.75 (dd, J = 9.1, 3.4 Hz, 1H),
3.87 (dq, J = 6.9, 2.6 Hz, 1H), 4.01 (dd, J = 10.2, 5.5 Hz, 1H), 4.27–4.32
(m, 1H), 4.43 (dd, J = 9.9, 2.6 Hz, 1H), 5.18 (d, J = 5.5 Hz, 1H), 7.43–7.50
(m, 2H), 7.55–7.65 (m, 2H), 8.97 (s, 2H), 9.03 (s, 1H).
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-7-{(4-
(pyridin-3-yl)phenylthio}lincomycin (72)
To a solution of 3-(4-bromophenyl)pyridine (75.4 mg, 0.32 mmol), 4,5-bis
(diphenylphosphino)-9,9-dimethylxanthene (13.4 mg, 0.023 mmol) and tris
(dibenzylideneacetone)dipalladium(0) (Pd2(dba)3) (12.3 mg, 13.4 μmol) in
1,4-dioxane (1 ml) were added to compound 71 (120.3 mg, 0.24 mmol) and
N,N-diisopropylethylamine (82 μl, 0.47 mmol) and refluxed for 5 h. The
mixture was filtrated by either Chromatodisc (0.45 μm) (Kurabo Industries)
or celite, concentrated under reduced pressure. The resulting residue was
purified by silica gel column chromatography (CHCl3/MeOH/28% aq.
NH4OH= 10/1/0.1) to obtain the title compound as an off-white solid
(125.9 mg, 80.4%). FAB-MS m/z 662 (M+H)+ as C33H47N3O7S2; 1H NMR
(400 MHz, CD3OD) δ 0.87–1.00 (m, 3H), 1.21–1.43 (m, 7H), 1.48 (s, 9H),
1.77–1.95 (m, 1H), 1.94, 1.97 (s x 2, 3H), 2.05–2.21 (m, 1H), 2.22–2.44
(m, 1H), 2.97 (t, J = 9.6 Hz, 1H), 3.59 (dd, J = 10.0, 3.2 Hz, 1H), 3.68 (br dd,
J = 9.8, 8.1 Hz, 1H), 3.85–4.01 (m, 2H), 4.05–4.16 (m, 1H), 4.28–4.41 (m, 1H),
4.41–4.50 (m, 1H), 4.51–4.64 (m, 1H), 5.27 (d, J = 5.5 Hz, 1H), 7.47–7.57
(m, 3H), 7.59–7.69 (m, 2H), 8.05–8.14 (m, 1H), 8.51 (dd, J = 4.8, 1.5 Hz, 1H)
and 8.78–8.83 (m, 1H).
In vitro antibacterial activity
MIC (μg ml− 1) was determined by the agar dilution method, which was
described in Clinical and Laboratory Standards Institute (M07-06 in 2003). Test
strains of S. pneumoniae and S. pyogenes were subjected to seed culture using
brain heart infusion agar (Becton Dickinson and Company, Tokyo, Japan) and
5% defibrinated horse blood. Test strains of H. influenzae were subjected to
seed culture using sensitivity disk agar-N ‘Nissui’ (Nissui, Tokyo, Japan), 5%
defibrinated horse blood, 5 μg ml− 1 Hemin and 15 μg ml−1 nicotinamide
adenine dinucleotide. A 5 μl portion of cell suspension of the test strains having
about 106 colony-forming unit per ml was inoculated into sensitivity disk agar-
N ‘Nissui’ supplemented with 5% defibrinated horse blood, 5 μg ml− 1 Hemin
and 15 μg ml− 1 nicotinamide adenine dinucleotide, and incubated at 37 °C for
18–22 h. Then, the MIC was measured.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
7(S)-1′-demethyl-7-deoxy-7-{(4-(pyridin-3-yl)phenylthio}
lincomycin (73)
ACKNOWLEDGEMENTS
We thank A Tamura, Dr E Shitara and Dr T Yoshida for encouragement and
valuable discussion. We are grateful to Professor Emeritus Dr M Konno for
supervision through our in-house drug discovery program in lincomycin field.
We also thank M Ishii for direction in intellectual properties, T Miyara, S Miki
and K Kaneda for analytical and synthetic chemistry, Y Takayama and K
Yamada for biological studies, and M Takagi for English manuscript.
Compound 72 (125.9 mg, 0.19 mmol) and 2,2,2-trifluoroacetic acid (0.29 ml)
in CH2Cl2 (2.5 ml) were treated at −20 °C for 10 min, and then treated at 0 °C
for 3 h according to the similar procedure as described for the preparation of 67
25
to afford 73 (99.1 mg, 92.7%) as a colorless solid. [α]D +91.4° (c 0.74,
MeOH); ESI-MS m/z 562 (M+H)+ as C28H39N3O5S2; TOF-ESI-HRMS (M+H)
+
calcd. for C28H39N3O5S2: 562.2409, found: 562.2407; 1H NMR (400 MHz,
CD3OD) δ 0.86–0.97 (m, 3H), 1.30–1.42 (m, 4H), 1.33 (d, J = 6.9 Hz, 3H),
1.77–1.87 (m, 1H), 1.97 (s, 3H), 2.02–2.13 (m, 2H), 2.59 (dd, J = 10.3, 8.0 Hz,
1H), 3.22 (dd, J = 10.3, 7.0 Hz, 1H), 3.58 (dd, J = 10.2, 3.3 Hz, 1H), 3.79 (br dd,
J = 3.3, 0.9 Hz, 1H), 3.86 (dd, J = 9.3, 3.7 Hz, 1H), 3.93 (dq, J = 6.9, 2.6 Hz,
1H), 4.10 (dd, J = 10.2, 5.6 Hz, 1H), 4.36–4.42 (m, 1H), 4.51 (dd, J = 9.9,
2.6 Hz, 1H), 5.27 (d, J = 5.6 Hz, 1H), 7.51 (ddd, J = 8.0, 4.9, 0.9 Hz, 1H),
7.51–7.58 (m, 2H), 7.60–7.68 (m, 2H), 8.07 (ddd, J = 8.0, 2.4, 1.6 Hz, 1H), 8.51
(dd, J = 4.9, 1.6 Hz, 1H) and 8.79 (dd, J = 2.4, 0.9 Hz, 1H).
1
2
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3
4
7(S)-1′-N-(tert-butoxycarbonyl)-1′-demethyl-7-deoxy-7-{4-
(pyrimidin-5-yl)phenylthio}lincomycin (74)
Compound 71 (116.4 mg, 0.23 mmol), 5-(4-bromophenyl)pyrimidine
(107.3 mg, 0.46 mmol), 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene
(14.2 mg, 0.024 mmol), Pd2(dba)3 (11.8 mg, 0.013 mmol) and N,N-diisopro-
pylethylamine (79.5 μl, 0.46 mmol) in 1,4-dioxane (1.5 ml) were treated for 6 h
according to the similar procedure as described for the preparation of 72 to
afford 74 (117.9 mg, 77.7%) as a colorless solid. FAB-MS m/z 663 (M+H)+ as
5
6
7
1
C32H46N4O7S2; H NMR (400 MHz, CD3OD) δ 0.86–1.00 (m, 3H), 1.25–1.43
(m, 7H), 1.48, 1.47 (s x 2, 9H), 1.80–1.95 (m, 1H), 1.92, 1.95 (s x 2, 3H),
2.04–2.20 (m, 1H), 2.21–2.44 (m, 1H), 2.97 (t, J = 9.6 Hz, 1H), 3.56–3.75
(m, 2H), 3.88–4.03 (m, 2H), 4.06–4.19 (m, 1H), 4.29–4.42 (m, 1H), 4.46
8
9
The Journal of Antibiotics

Synthesis and SAR of novel lincomycin analogs
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