De novo synthesis of novel bacterial monosaccharide fusaminic acid

Article abstract of DOI:10.1038/s41429-019-0170-3

Fusobacterium nucleatum is an oral bacteria related to various types of diseases. As Gram-negative bacteria, lipopolysaccharide (LPS) of Fusobacterium nucleatum could be a potential virulence factor. Recently, the structure of O-antigen in LPS of Fusobact

Full text of DOI:10.1038/s41429-019-0170-3

The Journal of Antibiotics
https://doi.org/10.1038/s41429-019-0170-3
SPECIAL FEATURE: ARTICLE
De novo synthesis of novel bacterial monosaccharide fusaminic acid
Ruohan Wei1 Han Liu Xuechen Li1
1 ●
●
Received: 18 December 2018 / Revised: 19 February 2019 / Accepted: 23 February 2019
©
The Author(s), under exclusive licence to the Japan Antibiotics Research Association 2019
Abstract
Fusobacterium nucleatum is an oral bacteria related to various types of diseases. As Gram-negative bacteria,
lipopolysaccharide (LPS) of Fusobacterium nucleatum could be a potential virulence factor. Recently, the structure of O-
antigen in LPS of Fusobacterium nucleatum strain 25586 was elucidated to contain a trisaccharide repeating unit -(4-β-
Nonp5Am-4-α-L-6dAltpNAc3PCho-3-β-D-QuipNAc)-. The nonulosonic acid characterized as 5-acetamidino-3,5,9-
trideoxy-L-glycero-L-gluco-non-2-ulosonic acid (named as fusaminic acid), and 2-acetamido-2,6-dideoxy-L-altrose are the
novel monosaccharides isolated. Herein we report the de novo synthesis of 5-N-acetyl fusaminic acid and the thioglycoside
derivative in order to further investigate the biological significance of nonulosonic acids for bacterial pathogenesis.
Introduction
to fetus thus causes term stillbirth in human pregnancies
14].
Although F. nucleatum infection results in numerous
[
Fusobacterium nucleatum is a Gram-negative anaerobic
bacterium found in human mouth [1]. It is one of the most
prevalent species in oral environment and regarded as a
dental pathogen to cause serious periodontal diseases
including periodontitis [2–6], gingivitis [2, 5, 7–9], and
endodontic infections [10–12]. Besides periodontal disease,
F. nucleatum is notorious for dissemination to cause a wide
spectrum of diseases, some of which are lethal [1, 13]. It
was reported that F. nucleatum causes diseases including
adverse pregnancy outcomes [14–17], GI disorders [18–20],
rheumatoid arthritis [21], respiratory tract infections [22],
Lemierre’s syndrome [22, 23], and Alzheimer’s diseases
serious diseases, little is known about the virulence factor.
So far, only one protein, FadA, was identified to be crucial
in colonization and infection of the bacteria [1, 13, 20].
FadA is not only an adhesin but also an invasin that binds to
cadhesin, which is widely distributed in tissues and cells,
and this might be the reason of migration of F. Nucleatum
[20, 25, 26]. LPS of the bacteria is also thought to be a
virulence factor participating in the infection. It was shown
that serum antibody levels to F. nucleatum LPS did corre-
late to poor oral health and the degree of periodontitis [27].
Recently, the structure of O-antigen of F. nucleatum
strain 25586 was identified and two novel sugars, 5-acet-
amidino-3,5,9-trideoxy-L-glycero-L-gluco-non-2-ulosonic
acid (fusaminic acid), and 2-acetamido-2,6-dideoxy-L-
altrose (6dAlt2NAc), were isolated and found as compo-
nents of the O-antigen (structures are shown in Fig. 1) [28].
Fusaminic acid attracts our interests due to its structural
similarity to pseudaminic acid and legionaminic acid. These
nonulosonic acids are unique to bacteria species, as the
congener of sialic acids, and considered as an important
virulence factor, although their precise roles in evasion of
the bacteria have not been elucidated yet [29]. Moreover,
being of crucial importance to Gram-negative bacteria, LPS
containing these molecules could be candidate targets for
developing new antimicrobial agents. However, the major
difficulty in investigating the biological significance of the
related nonulosonic acid is the inaccessibility of the target
molecules in homogeneous form as well as sufficient
[
24]. For instances, it was reported that the bacteria origi-
nating from mother’s subgingival plague could translocate
Dedication: This is dedicated to Professor Samuel. J. Danishefsky for
his great scientific contribution to total synthesis of highly complex
and biologically important natural products.
Supplementary information The online version of this article (https://
doi.org/10.1038/s41429-019-0170-3) contains supplementary
material, which is available to authorized users.
*
Xuechen Li
xuechenl@hku.hk
1
Department of Chemistry, State Key Laboratory of Synthetic
Chemistry, The University of Hong Kong, Hong Kong, P. R.
China

R. Wei et al.
amount. Herein we report a de novo total synthesis of
fusaminic acid based on the strategies applied in our
pseudaminic acid total synthesis reported recently [30].
corresponding aldehyde by indium-mediated Barbier type
allylation. The aldehyde can be derived via the Fukuyama
reduction from thioester 7, which can be constructed via the
aldol-type reaction of thioester derived isonitrile 8 [31] and
aldehyde 9. Aldehyde 9 can be prepared from commercial
available (S)-(-)-ethyl lactate via Weinreb-Nahm ketone
synthesis followed by 1,2-anti selective reduction and
ozonolysis. Our planned synthesis involves 3 chain elon-
gation steps with four new chiral centers formed during this
process. The absolute configuration of the chiral centers
generated has to be carefully determined. Armed with the
experience from our former synthesis of pseudaminic acid,
we anticipated that the stereoselectivity of the key trans-
formations could be modulated through utilization of dif-
ferent protecting groups with different electronic and steric
hindrance effect and optimization of reaction parameters.
To choose suitable protecting groups for the inter-
mediates, we first analyzed the stereoselectivity model of
the addition of aldehyde 9. In our recent total synthesis of
pseudaminic acid, the selectivity in the aldol-type addition
was achieved by lithium chelation of the protected β-
hydroxyl group and the aldehyde carbonyl group [30]. Less-
hindered protection of β-hydroxy group and bulky protec-
tion of α-hydroxyl group of aldehyde 9 were expected to
attribute to the diastereoselectivity. Taking these into con-
sideration, we chose p-methoxybenzyl (PMB) and t-butyl-
diphenylsilyl (TBDPS) ether, respectively (shown in
Scheme 2). The synthesis commenced with (S)-(-)-ethyl
lactate PMB ether protection, followed by saponification
and coupling with N, O-dimethylhydroxylamine to obtain
the Weinreb amide 13 in good yield. The latter was trans-
formed to vinyl ketone 15 via vinylmagnesium bromide
addition, and the corresponding diol 17 was obtained by
stereoselective reduction of the ketone via zinc borohydride
Results and discussion
Although the isolated fusaminic acid contains an amidine
group, we planned to synthesize the general N-acetyl deri-
vative, Fus5Ac 1. The retrosynthesis of Fus5Ac is shown in
Scheme 1. The α-keto acid structure can be obtained by
ozonolysis of the acrylate 6, which can be prepared from the
[
32, 33]. Chelation of zinc ion resulted in 1,2-anti selec-
tivity and the ratio of the diastereomers 17a/17b was around
0:1. The resultant diastereomeric mixture was inseparable
and then directly silylated with TBDPSCl followed by
1
Fig. 1 Structures of Fus5Ac, 6dAltNAc, Pse5Ac7Ac, Leg5Ac7Ac, and
polysaccharide in Fusobacterium nucleatum 25586 O-antigen
Scheme 1 Retrosynthesis of fusaminic acid 1

De novo synthesis of novel bacterial monosaccharide fusaminic acid
a
a
o
o
Scheme 2 Synthesis of key intermediate thioester 19 . Reagents and
−10 C, 1 h, 87% for 15 and 16. e Zn(BH4)2, diethyl ether, −20 C,
1 h.; f TBDPSCl, imidazole, DMF, ovn, 89% for 17, dr 10 : 1, 87% for
o
conditions: a NaH, PMBCl for 11, BnBr for 12, DMF/THF, 0 C to rt,
h, 81% for 11, 83% for 12. b LiOH, THF-MeOH-H2O, 2 h, quant. c
PivCl, Et N, 0 C, 1 h, then N,O-dimethylhydroxyamine, DCM, 0 C
o
2
18, dr 5 : 1, over 2 steps. g O3, DCM, −78 C, 0.5 h, then Ph3P.
h CNCH COSEt (8), LiOTf, DIPEA, DCE-DMF, 2 h. i 80% HOAc
o
o
3
2
to rt, 3 h, 92% for 13, 93% for 14. d vinylmagnesium bromide, THF,
(aq), 8 h, 45% over three steps
a
a
o
Scheme 3 Synthesis of hexosamine derivative . Reagents and con-
dition: aPd/C, Et3SiH, THF, 1 h. b Ph3P=COOtBu, DCM, 0.5 h. c
TBAF, HOAc, THF, 2 h, 62% over three steps. d 3% HCl in MeOH,
0 C to rt, 6 h. e Ac2O, Et3N, 86% over two steps. f BzCl, pyridine,
DMAP, DCM, ovn, 92%. g OsO4, NMO, THF-H2O, ovn. h Pd/C, H2,
MeOH, 3 h. i NaIO , DCM-H O, 6 h, 67% over three steps
4
2
ozonolysis to give aldehyde 9. With the key aldehyde in
hand, we tried to convert it to the thioester 19a by treating
the aldehyde with the isonitrile thioester in the presence of
lithium triflate and diisopropylethylamine, followed by
acidolysis of the 4,5-trans oxazoline intermediate in aqu-
eous acetic acid [30, 34–40]. Fortunately, we succeeded in
getting target diastereomers in good to moderate yield, but
the difficult separation remained a problem. Considering the
significance of confirming the chiral centers generated, and
the plausible complexity in the generation of the new chiral
center in the following Barbier allylation step, it would be
necessary to obtain the uniform diastereomer. To our
delight, we found that changing PMB ether to benzyl ether
simplified the purification without seriously impacting the
stereoselectivity, and more importantly, prevented partially
decomposition of PMB ether in ozonolysis and acidolysis.
We planned to convert the thioester to the corresponding
hexosamine derivative, 2-acetamido-2,6-dideoxy-L-altrose,
to confirm the absolute configuration. It is noted that the
altrose derivative, 6dAlt2NAc, is also the novel rare
monosaccharide found in the LPS of Fusobacterium
nucleatum strain 25586 [28].
Our initial attempts to directly convert the thioester to the
altrose hemiacetal failed due to the difficulty in removing
the benzyl ether. Catalytic hydrogenation or oxidation with
sodium bromate combined with sodium dithionite [41]
could not free the hydroxyl group without affecting the
thioester. While deprotecting the benzyl ether after the
Fukuyama reduction [42] was also challenging due to
the difficulty in manipulating the corresponding α-N-formyl
aldehyde. Thus, we firstly converted the thioester to the
aldehyde and trapped the resultant aldehyde with ylide to
give the α,β-unsaturated ester (shown in Scheme 3). With
this stable olefin as the surrogate to the aldehyde, we had
the chance to manipulate the protecting groups. Different
solvents such as DCM, acetone, THF were tried to prevent
partially triethylsilyl (TES) installation in the Fukuyama
reduction, while the silylation seemed to be inevitable [43].
Therefore, we directly removed all silyl ethers by tetra-
butylammonium fluoride (TBAF) to give product 20. The
formamide 20 was converted to acetamide 21 by acidolysis
with methanolic hydrochloride followed by acetylation with
acetic anhydride and trimethylamine in 86% yield [44]. The
hydroxyl groups were masked by benzoyl chloride in order

R. Wei et al.
to prevent side reactions in the following dihydroxylation
and vicinal diol cleavage steps. Osmium tetraoxide was
used for dihydroxylation, and benzyl ether could be
removed by catalytic hydrogenation without affecting any
other functional groups at this step. Finally, the hemiacetal
The indium-mediated Barbier type allylation is the key
step for carbon chain elongation due to its compatibility
with various functional groups [45]. Successful conversion
of the aldehyde to the desired acrylate was achieved by
mixing the aldehyde generated via the Fukuyama reduction
with organoindium species generated beforehand in situ in
the mixture of ethanol and aqueous ammonium chloride
[46]. After simple aqueous work-up, the reaction mixture
was subjected to TBAF in THF solution buffered with
acetic acid to remove the TBDPS group. Two diastereomers
2
5 was formed by converting the diol 24 to aldehyde via the
Malaprade reaction. With the altrose derivative 25 in hand,
we carefully examined the configuration of the chiral cen-
ters newly generated.
As the 1,2-anti selective reduction of α-hydroxyl ketone
via zinc borohydride was an established method, the abso-
lute configuration of C-4 obtained from enantiopure starting
material (S)-(-)-ethyl lactate could be settled [33]. Moreover,
the isonitrile addition to the aldehyde would form 4,5-trans
oxazoline in the presence of base and the following acid-
olysis did not affect the chiral center, thus the relative con-
figuration of C-2 was also determined [34–40]. Although
starting with a 5:1 mixture of the diastereomers of the vinyl
alcohol, we could get the major diastereomer of the thioester
in 45% yield in pure form, which excluded the contribution
of the minor syn diol from the reduction step to the isolated
thioester. Therefore, the thioester could only be 19a or 19b.
Compound 19a is the precursor of 2-acetamido-2,6-dideoxy-
L-altrose while 19b derives to 2-acetamido-2,6-dideoxy-L-
glucose, also known as N-acetyl-L-quinovosamine (shown in
1
were formed with ratio of 5.5:1 as shown in H NMR
spectrum, which were readily separated by silica gel column
chromatography to give the major diastereomer 26a in 59
yield%. Regarding the previous experience in pseudaminic
acid synthesis and similar compounds in the Seeberger’s
[46] and Ito’s [47] syntheses, we proposed that the major
diastereomer 26a should possess the desired configuration
at the newly formed chiral center [30, 40, 41]. The for-
mamide was converted to acetamide as described above
with partially intramolecular lactonization (27/27a), and the
five-membered ring lactone could be hydrolyzed in 1 M
NaOH solution to provide free acid 28 after careful neu-
tralization. However, direct ozonolysis of the acid 28 gave
unsuccessful result, while numerous byproducts including
glycal were generated. To our delight, we found that pro-
tection of the carboxylic acid as benzyl ester 27 could
significantly suppress side reactions, and the following
ozonolysis gave hemiketal 29 in good yield. After final
hydrogenation to remove benzyl groups, we successfully
obtained the target molecule, Fus5Ac 1 (Shown in
Scheme 4).
In order to further confirm the configuration of Fus5Ac
synthesized, we derived 29 to thioglycoside 31 via thio-
glycosylation of acetate 30. Relatively large JC1, H3a value
(~6.4 Hz) indicates the equatorial orientation of the thiol
aglycone (β). The small vicinal proton coupling constants of
JH3a,H4, JH3e,H4, JH4,H5, and JH5,H6 (3.5, 2.0, < 0.1, 2.0 Hz,
respectively) indicate the equatorial orientation of both H-4
and H-5. Combining with relatively large JH6, H7 (7.5 Hz),
we identified C4-C7 as gluco configuration [48]. Moreover,
the spin system of the synthetic fusaminic acid 1 was highly
consistent with the isolated sample as well as 5,7-
1
Fig. 2). Peaks of this N-acetyl quinovosamine in H-NMR
spectrum should fit well to N-acetyl glucosamine pattern, of
which peaks have large vicinal coupling constant as all
protons in have axial orientation. On the contrary, for the
altrose derivative in which protons orient both axially and
equatorially, small vicinal coupling constants should be. We
assigned protons of 24 and found several small coupling
constant values such as JH4,H5 (3 Hz, see Experimental sec-
tion). Although some of the small coupling constants may
come from the deviation from the typical chair-like con-
formation, the observed coupling patterns significantly dif-
ferent from the quinovosamine derivatives excluded the
possibility of the structure 19b. We decided to use the major
diastereomer 19a to continue the synthesis of fusaminic acid
and planned to further confirm the configurations by com-
paring the splitting pattern of the synthetic final product with
the isolated one.
Fig. 2 Elucidation of the configurations of isonitrile adducts via derivatization to hexosamine

De novo synthesis of novel bacterial monosaccharide fusaminic acid
a
a
Scheme 4 De novo synthesis of fusaminic acid . Reagents and con-
ditions: a Pd/C, Et3SiH, THF, 1h. b Benzyl bromomethacrylate, indium
powder, NH4Cl, EtOH, 2 h. c TBAF, HOAc, THF, 2 h, 59% over three
steps; f 1M NaOH aqueous solution, 1 h, 87%.; g K2CO3, BnBr, DMF,
5 h, 79%.; h O3, −78 C, DCM-MeOH, 0.5 h, then Me2S, 75%.; i Pd
o
(OH)2/C, H2, MeOH-H2O, 12 h, 89%.; j Ac2O, pyridine, DMAP, 3 h,
o
.
steps. d 3% HCl in MeOH, 0 C to rt, 6 h. e Ac2O, Et3N, 89% over two
83%.; k p-TolSH, BF3 Et2O, dry DCM, ovn, 62%
diacetamido-3,5,7,9-tetradeoxy-L-glycero-L-gluco-non-2-
ulosonic acid (compound 42 in ref. [48]) [28].
was performed on silica gel 60-F254 precoated on glass
plate (E. Merck), with detection by fluorescence and/or or
by staining with acidic ceric ammonium molybdate. The
normal phase column chromatography was performed on
silica gel (230–400 mesh, Merck), while the reverse phase
chromatography was performed on C18 silica gel (Davisil
In summary, we have developed the de novo total
synthesis of a newly discovered nonulosonic acid unique to
bacteria, fusaminic acid. The synthesis started with com-
mercial available (S)-(-)-ethyl lactate, involving 18 steps to
give Fus5Ac in 8% overall yield. The key steps include the
diastereoselective addition of the thioester derived isonitrile
to aldehyde and indium-mediated diastereoselective
Barbier-type allylation. We derived the key thioester inter-
mediate to 6dAltNAc and synthesized fusaminic acid thio-
glycoside donor for structure confirmation. The success in
generating the thioglycoside broadens the application of the
synthesis as it provides the opportunity to assembly com-
plex fusaminylated glycan and glycoconjugates.
1
13
633NC18E, Grace Materials Technologies). The H and
C
NMR spectra were recorded on Advance DRX Bruker 400/
o
500 MHz spectrometers at 25 C. The 2D NMR spectra
were recorded on Advance DRX Bruker 500 MHz spec-
o
trometers at 25 C. The high-resolution mass spectrometry
was performed on a Waters Micromass Q-TOF Premier
Mass Spectrometer.
Ethyl (S)-2-(benzyloxy)propanoate (12)
To a mixture of anhydrous THF (20 mL) and DMF (20 mL)
in round bottle flask was added sodium hydride (1.76 g, 44
mmol, 1.1 equiv, 60% suspension in mineral oil) followed
Experimental section
General
by (S)-(−)-ethyl lactate (4.63 mL, 40 mmol, 1.0 equiv) at
o
0
C. After strring for 10 min, benzyl bromide (7.13 mL,
Commercially available reagents were used without further
purification, unless otherwise stated. The anhydrous sol-
vents were either prepared from AR grade solvents via
standard methods (DCM, THF, etc.), or purchased in
anhydrous form (DMF, pyridine, etc.). The analytical TLC
60 mmol, 1.5 equiv) was added. The reaction mixture was
warmed to room temperature and monitored by TLC. After
full conversion (about 2 h) of the starting material, the
reaction was quenched by sat. NH Cl (aq), then diluted with
4
ethyl acetate (500 mL) and water (100 mL). The organic

R. Wei et al.
layer was separated and washed sequentially with 1 M HCl
aq, 100 mL), sat. NaHCO (aq, 100 mL), and brine (100
(S)-4-(benzyloxy)pent-1-en-3-one (16)
(
3
mL). The organic layer was dried over anhydrous Na SO ,
and concentrated under vacuum. The residue was purified
by silica gel flash chromatography using n-hexane: ethyl
To a solution of Weinreb amide 14 (7.20 g, 30.9 mmol) in
anhydrous THF (100 mL) was added vinylmagnesium
bromide (1.0 M solution in THF, 46.3 mL, 1.5 equiv)
2
4
o
acetate 12: 1 v/v as eluent to obtain compound 12 as col-
dropwise at −20 C. The reaction mixture was gradually
1
orless oil (6.90 g, 83%). H NMR (500 MHz, CDCl ) δ
warmed to r.t. and kept stirring for 2 h. After full conversion
achieved, the reaction mixture was poured into a cold 1 M
HCl aqueous solution. The mixture was extracted with ethyl
acetate (500 mL) and washed with sat. NaHCO3 (aq,
100 mL) and brine (100 mL). The solvent was removed
under vacuum and the residue obtained was purified by
silica gel flash chromatography using n-hexane: ethyl
3
7
.28–7.40 (5 H, m), 4.72 (1 H, d, J = 11.5 Hz), 4.47 (1 H, d,
J = 11.5 Hz), 4.19–4.28 (2 H, m), 4.07 (1 H q, J = 7.0 Hz),
1
3
1
.46 (3 H, d, J = 6.5 Hz), 1.31 (3 H, t, J = 7.0 Hz);
C
NMR (125 MHz, CDCl ) δ 173.2, 137.6, 128.4, 14.2,
3
1
28.0, 127.8, 74.1, 72.0, 60.8, 18.7; HR-ESI-MS (m/z):
+
+
calcd for C H O Na (M + Na ): 231.0992, found 231.
1
2
16
3
0
998.
acetate 15: 1 v/v as eluent to obtain compound 14 as col-
1
orless oil (5.10 g, 87%). H NMR (500 MHz, CDCl ) δ
3
(
S)-2-(benzyloxy)-N-methoxy-N-methylpropanamide
7.34–7.38 (4 H, m), 7.28–7.33 (1 H, m), 6.81 (1 H, dd, J =
17.5, 11.0 Hz), 6.45 (1 H, dd, J = 17.5, 1.5 Hz), 5.80 (1 H,
dd, J = 10.5, 1.5 Hz), 4.58 (1 H, d, J = 12.0 Hz), 4.46 (1 H,
d, J = 11.5 Hz), 4.13 (1 H, q, J = 7.0 Hz), 1.39 (3 H, d, J =
(14)
To a stirred solution of 12 (6.90 g, 33.2 mmol, 1.0 equiv) in
MeOH (15 mL) and THF (60 mL), the solution of LiOH
1
3
7.0 Hz); C NMR (125 MHz, CDCl ) δ 201.0, 137.5,
3
(
2.0 eq in 15 mL H O) was added. The mixture was stirred
130.93, 129.68, 128.39, 127.81, 127.76, 79.7, 71.7, 17.6;
2
+
+
at r.t. for 2 h. After the full conversion was achieved, the
mixture was acidified by 1 M HCl (aq). The mixture was
diluted with ethyl acetate (500 mL), and the organic layer
was separated. The aqueous layer was extract with ethyl
acetate (200 mL) again, and the organic layer was com-
bined. The organic layer was washed with brine (2 × 100
mL) and dried over anhydrous Na SO . The solvent was
removed under vacuum and the residue was further dried
under oil pump for 3 h. The residue above was used in the
next step without purification.
HR-ESI-MS (m/z): calcd for C H O Na (M + Na ):
12 14 2
213.0886, found 246. 0894.
(((R)-4-(benzyloxy)pent-1-en-3-yl)oxy)(tert-butyl)
diphenylsilane (18a/b)
To a solution of the vinyl ketone 16 (5.10 g, 26.8 mmol, 1.0
equiv) in anhydrous diethyl ether (200 mL) was added zinc
borohydride (0.2 M solution in diethyl ether, 135 mL, 1.0
2
4
o
equiv) dropwise at −20 C. The reaction was kept stirring at
The saponification product was dissolved in anhydrous
DCM (200 mL) and cooled to 0 C. Triethylamine
11.6 mL, 82.9 mmol, 2.5 equiv) was added to the solution
the temperature for 3 h. When full conversion was achieved,
the reaction was quenched by carefully adding 1 M HCl
(aq), then diluted with ethyl acetate (200 mL) and water
(100 mL). The organic phase was separated and washed
o
(
above followed by PivCl (4.49 mL, 36.5 mmol, 1.1 eq) was
o
added dropwise and the solution was kept stirring at 0 C
with sat. NaHCO (aq, 100 mL) and brine (100 mL). The
3
for 1 h. Then N, O-dimethyl hydroxylamine hydrochloride
solvent was removed under vacuum and the residue was
purified by silica gel flash chromatography using n-hexane:
ethyl acetate 5: 1 v/v as eluent to obtain (4 S)-4-(benzyloxy)
(
3.88 g, 39.8 mmol, 1.2 equiv) was added and the reaction
mixture was warmed to r.t. and kept stirring for another 3 h.
After full conversion (monitored by TLC), the mixture was
diluted with ethyl acetate (500 mL) and washed with 1 M
pent-1-en-3-ol as colorless oil (5 (anti): 1 (syn) mixture of
1
diastereomers, 4.75 g, 92%). H NMR (500 MHz, CDCl ) δ
3
HCl (aq, 100 mL), sat. NaHCO (aq, 100 mL) and brine
7.36–7.41 (4 H, m), 7.30–7.35 (1 H. m), 5.90 (1 H, ddd,
J = 17.5, 11.0, 6.0 Hz), 5.36 (1 H, dt, J = 17.0, 1.5 Hz),
5.25 (1 H, dt, J = 11.0, 1.5 Hz), 4.66 (1 H, d, J = 12.0 Hz),
4.57 (1 H, d, J = 12.0 Hz), 4.25–4.29 (1 H, m), 3.64 (1 H,
3
(
100 mL) subsequently. The solvent was removed under
vacuum and the residue obtained was purified by silica gel
flash chromatography using n-hexane: ethyl acetate 3:1 v/v
as eluent to obtain compound 14 as slightly yellow oil
ddd, J = 12.5, 6.5, 3.5 Hz), 2.61 (1 H, d, J = 4.0 Hz), 1.20
1
13
(
7.20 g, 93%). H NMR (500 MHz, CDCl ) δ 7.24–7.36 (5
(3 H, d, J = 6.5 Hz); C NMR (125 MHz, CDCl ) δ 138.4,
3
3
H, m), 4.64 (1 H, d, J = 12.0 Hz), 4.36–4.41 (2 H, m), 4.07
1 H, q, J = 7.0 Hz,), 3.55 (3 H, s), 3.18 (3 H, s), 1.38 (3 H,
136.7, 128.5, 127.7, 116.4, 77.5, 74.6, 70.8, 14.0; HR-ESI-
+
+
(
MS (m/z): calcd for C H O Na (M + Na ): 215.1043,
12 16 2
1
3
d, J = 6.5 Hz,); C NMR (125 MHz, CDCl ) δ 137.8,
found 245. 1050.
3
1
28.3, 127.9, 127.7, 71.1, 61.2, 17.9; HR-ESI-MS (m/z):
To a solution of the alcohol above (4.75 g, 24.7 mmol)
in DMF solution (30 mL) was added imidazole (3.36 g,
43.4 mmol, 2.0 equiv) and TBDPSCl (9.63 mL, 37.0 mmol,
+
+
calcd for C H NO Na (M + Na ): 246.1101, found
2
1
2
17
3
46. 1109.

De novo synthesis of novel bacterial monosaccharide fusaminic acid
1
.5 equiv). The mixture was kept stirring for 8 h and
solvent was removed under vacuum and the residue was
monitored by TLC. After full conversion, the mixture was
diluted with ethyl acetate (500 mL) and washed with 1 M
purified by silica gel flash chromatography using n-hexane:
ethyl acetate 3: 1 v/v as eluent to obtain 19a as white solid.
1
HCl (aq, 100 mL), sat. NaHCO (aq, 100 mL) and brine
(6.44 g, 45%). H NMR (500 MHz, CDCl 3: 1 mixture of
3
3,
(
100 mL) subsequently. The solvent was removed under
two rotamers) δ 7.66–7.71 (4 H, m, major), 7.60–7.65 (1.33
H, m, minor), 7.19–7.47 (14.6 H, m, major and minor), 6.27
(1 H, d, J = 8.5 Hz, major), 6.05 (0.33 H, t, J = 11.0 Hz,
minor), 4.98 (1 H, d, J = 9.0 Hz, major), 4.51–4.56 (1.66 H,
m, major and minor), 4.44 (1 H, d, J = 11.5 Hz, major),
4.42 (0.33 H, d, J = 12.5 Hz, minor), 4.30 (1 H, d, J = 12.5
Hz, major), 4.19 (0.33 H, d, J = 10.0 Hz, minor), 3.72 (1 H,
qd, J = 6.5, 2.0 Hz, major), 3.81 (0.33 H, qd, J = 6.5, 1.5
Hz, minor), 3.67 (0.33 H, dd, J = 8.5, 1.5 Hz, minor), 3.58
(1 H, dd, J = 8.0, 1.5 Hz, major), 3.21 (1 H, d, J = 3.5 Hz,
major), 3.05 (0.33 H, d, J = 4.0 Hz, minor), 2.88–2.95
(2.66 H, m, major and minor), 1.26 (3 H, t, J = 7.5 Hz,
major), 1.25 (1 H, t, J = 7.5 Hz, minor), 1.06 (9 H, s,
major), 1.05 (3 H, s, minor), 1.02 (1 H, d, J = 7.0 Hz,
vacuum and the residue obtained was purified by silica
gel flash chromatography using n-hexane: ethyl acetate 40:
1
v/v as eluent to obtain compound 18a/b as colorless oil
5 (anti): 1 (syn) mixture of diastereomers, 10.63 g, 97%).
(
1
H NMR (500 MHz, CDCl ) δ 7.85–7.88 (2 H, m),
3
7
.79–7.84 (2 H, m), 7.35–7.55 (11 H, m), 6.03 (1 H, ddd,
J = 17.0, 10.0, 7.0 Hz), 5.16 (1 H, dt, J = 10.5, 1.0 Hz),
5
4
.07 (1 H, dt, J = 17.0, 1.0 Hz), 4.73 (1 H, d, J = 12.0 Hz),
.66 (1 H, d, J = 12.0 Hz), 4.33–4.36 (1 H, m), 3.66 (1 H,
13
ddd, J = 13.0, 6.5, 3.0 Hz), 1.23–1.28 (12 H, m); C NMR
125 MHz, CDCl ) δ 139.2, 137.5, 136.25, 136.21, 134.23,
(
1
1
3
34.13, 129.65, 129.59, 128.3, 127.61, 127.53, 127.42,
27.34, 116.7, 78.8, 78.2, 71.5, 27.2, 19.6, 15.8; HR-ESI-
+
+
13
MS (m/z): calcd for C H O SiNa (M + Na ): 453.2220,
minor), 0.92 (3 H, d, J = 7.0 Hz, major); C NMR (125
28
34
2
found 453.2231.
MHz, CDCl ) δ 199.7 (major), 164.3 (minor), 161.3
3
(major), 138.2 (major), 138.1(minor), 136.3 (major), 136.14
S-Ethyl (2 R,3 R,4 R,5 S)-5-(benzyloxy)-4-((tert-
butyldiphenylsilyl)oxy)-2-formamido-3-
hydroxyhexanethioate (19a)
(major), 136.09 (minor), 133.9 (major), 133.1 (minor),
132.9 (minor), 132.5 (major), 130.5 (minor), 130.3 (minor),
130.2 (major), 129.8 (major), 128.64 (minor), 128.58
(major), 128.2 (minor), 128.0 (major), 127.9 (minor), 127.8
The solution of 18a/b (10.6 g, 24.7 mmol) in DCM
(major), 127.7 (major and minor), 127.5 (major and minor),
79.3 (minor), 78.9 (major), 76.3 (major), 75.5 (minor), 74.0
(major), 73.9 (minor), 71.7 (minor), 71.4 (major), 62.5
(minor), 59.4 (major), 24.0 (minor), 23.7 (major), 19.6
(major and minor), 17.5 (minor), 17.2 (major), 14,37
(major), 14.35 (minor); HR-ESI-MS (m/z): calcd for
o
(
150 mL) was cooled to −78 C. The O (generated from O
3
2
and carried by the flow of O ) was bubbled through this
2
solution. The color of the solution truned purple, which
indicated the saturation of O in DCM. The excess amount
3
of O was blown off by the flow of O and the purple color
3
2
+
+
disappeared. To this solution, Me S (2 mL) was added to
C H NO SiSNa (M + Na ): 602.2367, found 602.2376.
32 41 5
2
reduce the peroxide intermediate. After 1 h reduction at r.t.,
the solution was diluted with DCM (500 mL) and washed
with water (100 mL) to remove DMSO (generated from
tert-Butyl (4 S,5 R,6 R,7 S,E)-7-(benzyloxy)-4-
formamido-5,6-dihydroxyoct-2-enoate (21)
Me S). The solvent was removed under vacuum and the
2
residue was used in the next step without further
purification.
To a 50 mL round bottle flask, thioester 19a (579 mg, 1.0
mmol, 1.0 equiv) and Pd/C (10% Pd on activated carbon,
100 mg, 0.1 equiv based on Pd) were added. After agron
protection of the flask, anhydrous DCM (5 mL) was added,
To the solution of the above aldehyde in DCE (125 mL),
isonitrile 8 (3.83 g, 29.6 mmol, 1.2 equiv) was added, fol-
lowed by the solution of LiOTf (4.62 g, 29.6 mmol, 1.2
equiv) in anhydrous DMF (25 ml). The final concentration
of the aldehyde was controlled at 0.2 M. To this mixture,
DIPEA (0.86 ml, 4.94 mmol, 0.2 equiv) was added to
initiate the reaction. The mixture was stirred at r.t. for 2 h,
then was diluted with DCM (500 ml) and thoroughly
washed with water and brine. The organic phase was con-
centrated under vacuum. The residue was dissolved in 80%
acetic acid aqueous solution (30 mL) and kept stirring for
and the mixture was stirred mildly. Et SiH (0.60 mL, 3.8
3
mmol, 3.8 equiv) was added dropwise during 20 min, then
the mixture was mildly stirred at r.t. for 2 h. When full
conversion achieved, the mixture was filtered through celite.
To the filtrate was added (tert-butoxycarbonylmethylene)
triphenylphosphorane (451 mg, 1.2 mmol, 1.2 eq), and the
mixture was kept stirring for 1 h. After full conversion as
indicated by TLC, the solvent was removed under vacuum.
The residue was re-dissolved in THF (10 mL) and a mixture
of TBAF (1.0 M solution in THF, 3.0 mL, 3.0 equiv) and
acetic acid (90 μL, 1.5 mmol, 1.5 equiv) were added. The
mixture was then kept stirring for 2 h and monitored by
TLC. After full conversion, the reaction mixture was diluted
8
h. The acetic acid was removed under vacuum and the
residue was diluted with ethyl acetate (500 mL). The mix-
ture was washed with sat. NaHCO (aq, 3 × 100 mL) and
3
brine (100 mL), and dried over anhydrous Na SO . The
2
4

R. Wei et al.
with ethyl acetate (200 mL), washed with brine (2 × 50 mL),
and dried over anhydrous Na SO . The solvent was
removed under vacuum and the residue was purified by by
silica gel flash chromatography using DCM: ethyl acetate
DMAP (4 mg, 0.03 mmol, 0.05 eq). The reaction was kept
stirring for 16 h. When full conversion was achieved, the
mixture was diluted with ethyl acetate (200 mL), and
2
4
washed with 1 M HCl (aq, 3 × 50 mL), sat. NaHCO (aq,
3
3
:1 v/v as eluent to obtain 21 as white foam. (235 mg, 62%).
50 mL) and brine (50 mL) and dried over anhydrous
Na SO . The solvent was removed under vacuum and the
1
H NMR (500 MHz, CDCl ) δ 8.26–8.28 (1 H, m),
3
2
4
7
(
(
.29–7.37 (5 H, m), 6.89 (1 H, dd, J = 15.5, 4.5 Hz), 6.25
1 H, d, J = 9.0 Hz), 5.94 (1 H, dd, J = 16.0, 2.0 Hz), 5.09
1 H, q, J = 4.5 Hz), 4.70 (1 H, d, J = 11.0 Hz), 4.43 (1 H,
residue was purified by silica gel flash chromatography
using n-hexane: ethyl acetate 3: 1 v/v as eluent to obtain 23
as white foam (318.2 mg, 92%). H NMR (500 MHz,
1
d, J = 11.5 Hz), 3.77 (1 H, dd, J = 8.5, 1.0 Hz), 3.71 (1 H,
dd, J = 8.0, 6.0 Hz), 3.17 (1 H, t, J = 8.5 Hz), 1.48 (9 H, s),
CDCl ) δ 8.00 (2 H, d, J = 7.5 Hz), 7.93 (2 H, d, J = 7.5
3
Hz), 7.59 (2 H, t, J = 7.0 Hz), 7.40–7.47 (4 H, m),
7.25–7.36 (10 H, m), 6.84 (1 H, dd, J = 16.0, 5.0 Hz), 6.20
(1 H, d, J = 9.0 Hz), 5.78 (1 H, d, J = 15.5 Hz), 5.69 (1 H, t,
J = 5.0 Hz), 5.60 (1 H, t, J = 5.0 Hz), 5.21–5.28 (1 H, m),
4.63 (1 H, d, J = 11.0 Hz), 4.58 (1 H, d, J = 11.0 Hz),
3.92–3.99 (1 H, m), 1.86 (3 H, s), 1.42 (9 H, s), 1.34 (3 H, d,
13
1
1
8
.38 (3 H, d, J = 6.0 Hz); C NMR (125 MHz, CDCl ) δ
65.2, 162.4, 143.7, 137.3, 128.85, 128.35, 128.19, 124.8,
3
1.0, 79.6, 72.3, 71.0, 50.0, 28.3, 16.8; HR-ESI-MS (m/z):
+
+
calcd for C H NO Na (M + Na ): 402.1887, found
2
0
29
6
4
02.1896.
1
3
J = 6.0 Hz); C NMR (125 MHz, CDCl ) δ 169.4, 165.53,
3
tert-Butyl (4 S,5 R,6 R,7 S,E)-4-acetamido-7-
benzyloxy)-5,6-dihydroxyoct-2-enoate (22)
165.51, 165.1, 142.8, 137.7, 133.68, 133.53, 129.90,
129.65, 129.32, 128.71, 128.70, 128.63, 128.22, 128.02,
(
1
24.6, 80.8, 74.00, 73.92, 73.0, 71.4, 50.5, 28.2, 23.3, 16.1;
+
+
To a 50 mL round bottle flask containing compound 21
235 mg, 0.62 mmol, 1.0 equiv), a solution of HCl (aq) in
HR-ESI-MS (m/z): calcd for C H NO Na (M + Na ):
35 39 8
(
624.2568, found 624.2580.
MeOH (3%, 12.0 mL prepared from conc. HCl 1.0 mL and
o
MeOH 11.0 mL) cooled to 0 C was added. The reaction
2-Acetamido-3,4-di-O-benzoyl-2,6-dideoxy-L-altrose
(25)
mixture was gradually warmed to r.t. and kept stirring for
6
h. After full conversion as indicated by TLC, the mixture
o
was cooled to 0 C again and triethylamine was added until
the solution turned basic. Acetic anhydride (120 μL, 1.24
mmol, 2.0 equiv) was added and the solution was kept
stirring for 1 h in basic environment. After full conversion,
the reaction was diluted with ethyl acetate (200 mL),
To a mixture of compound 23 (318 mg, 0.53 mmol,
1.0equiv) in THF (6 mL) and H O (2 mL) was added OsO4
2
(0.04 M solution in H O, 265 μL, 0.02 equiv) and 4-
2
methylmorpholine 4-oxide (NMO, 4.8 M solution in H O,
2
550 μL, 5.0 equiv). The mixture was kept stirring for 8 h.
When full conversion was achieved, the mixture was
quenched with sat. Na S O (aq), then diluted with ethyl
washed with1 M HCl (aq, 50 mL), sat. NaHCO (aq, 50
3
mL) and brine (50 mL), and dried over anhydrous Na SO .
2
4
2
2
3
The solvent was removed under vacuum and the residue
was purified by silica gel flash chromatography using DCM:
acetate (200 mL), and washed with brine (50 mL). The
organic solvent was dried over Na SO and concentrated
2
4
ethyl acetate 3:1 v/v as eluent to obtain 22 as white foam
under vacuum. The residue was purified by silica gel flash
chromatography using n-hexane: ethyl acetate 2: 3 v/v to
obtain 24 as white foam. (286.4 mg, 85%)
1
(
(
209.6 mg, 86%). H NMR (500 MHz, CDCl ) δ 7.27–7.37
5 H, m), 6.88 (1 H, dd, J = 16.0, 4.5 Hz), 6.01 (1 H, d, J =
3
9
4
.0 Hz), 5.91 (1 H, d, J = 16.0 Hz), 4.96–5.01 (1 H, m),
.71 (1 H, d, J = 11.0 Hz), 4.42 (1 H, d, J = 11.0 Hz), 3.75
To a round bottom flask containing compound 24
(143.2 mg, 0.225 mmol), Pd/C (10% Pd on activated carbon,
50 mg) was added. The flask was filled with argon and
methanol (10 mL) was added. The mixture was kept stirring
(
8
1 H, d, J = 8.5 Hz), 3.66–3.73 (1 H, m), 3.08 (1 H, t, J =
.5 Hz), 2.10 (3 H, s), 1.48 (9 H, s), 1.39 (3 H, d, J = 6.0
1
3
Hz); C NMR (125 MHz, CDCl ) δ 172.1, 165.2, 144.4,
under 1 atm H atmosphere and monitored by TLC. After full
3
2
1
5
37.3, 128.8, 128.3, 128.2, 124.5, 81.0, 80.0, 72.4, 71.1,
conversion, the mixture was filtered through celite to remove
the catalyst. The filtrate was concentrated under vacuum and
used in the next step without further purification.
1.2, 28.2, 23.2, 17.1; HR-ESI-MS (m/z): calcd for
+
+
C H NO Na (M + Na ): 416.2044, found 416.2058.
2
1
31
6
To the solution of the above residue in DCM (10 mL)
(2 S,3 S,4 R,5 S,E)-5-acetamido-2-(benzyloxy)-8-(tert-
was added a solution of NaIO (241 mg, 1.13 mmol, 5.0
4
butoxy)-8-oxooct-6-ene-3,4-diyl dibenzoate (23)
equiv) in H O (5 mL). The reaction mixture was kept vig-
2
orous stirring for 6 h. After full conversion, the mixture was
diluted with ethyl acetate (200 mL), and washed with brine
(50 mL). The organic solvent was dried over Na SO and
To a solution of compound 22 (235 mg, 0.53 mmol, 1.0 eq)
in anhydrous pyridine (10 mL) was added benzoyl chloride
2
4
(
173 μL, 1.32 mmol, 2.5 equiv) dropwise, followed by
concentrated under vacuum. The residue was purified by

De novo synthesis of novel bacterial monosaccharide fusaminic acid
silica gel flash chromatography using DCM: methanol 40:
chromatography using DCM: ethyl acetate 3: 2 v/v as eluent
to obtain compound 26a/b as white foam. (6 (4 R): 1 (4 S)
mixture of diastereomers, 1.35 g for the major diastereomer,
1
v/v as eluent to obtain 25 as white foam (76.2 mg, 82%).
1
H NMR (500 MHz, CDCl ) δ 7.60 (2 H, t, J = 7.5 Hz,
3
ArH), 7.52 (2 H, t, J = 7.5 Hz, ArH), 7.47 (3 H, t, J =
59% over 3 steps). For major diastereomer 26a: [α] + 27.25
1
7
.5 Hz, ArH), 7.37 (3 H, t, J = 7.5 Hz, ArH), 6.60 (1 H, d,
J = 8.0 Hz, NH), 5.66 (1 H, qd, J = 6.5, 3.0 Hz, H-5), 5.50
1 H, dd, J = 9.5, 3.0 Hz, H-4), 4.65 (1 H, d, J = 9.0 Hz, H-
(c 0.6, DCM); H NMR (500 MHz, CDCl ) δ 8.32 (1 H, s),
3
7.28–7.37 (10 H, m), 6.54 (1 H, d, J = 9.0 Hz), 6.31 (1 H,
s), 5.66 (1 H, s), 5.20 (1 H, d, J = 12.5 Hz), 5.18 (1 H, d,
J = 12.5 Hz), 4.94 (1 H, s), 4.74 (1 H, s), 4.70 (1 H, d, J =
11.5 Hz), 4.41 (1 H, d, J = 11.5 Hz), 4.27 (1 H, t, J = 8.5
Hz), 4.15 (1 H, d, J = 9.0 Hz), 3.88 (1 H, s), 3.81 (1 H, d,
J = 9.0 Hz), 3.63–3.70 (1 H, m), 3.10 (1 H, t, J = 8.0 Hz),
(
3
2
), 4.44 (1 H, dd, J = 8.0, 2.0 Hz, H-2), 4.10 (1 H, s, OH),
.05 (3 H, s, CH CO), 1.52 (3 H, d, J = 6.5 Hz, H-6); HR-
3
+
+
ESI-MS (m/z): calcd for C H NO Na (M + Na ):
22
23
7
4
36.1367, found 436.1375.
2
.56 (1 H, dd, J = 14.0, 7.5 Hz), 2.41 (1 H, dd, J = 14.0,
1
3
Benzyl (4 R/S,5 S,6 R,7 R,8 S)-8-(benzyloxy)-5-
formamido-4,6,7-trihydroxy-2-methylenenonanoate
6.0 Hz), 1.38 (3 H, d, J = 6.0 Hz); C NMR (125 MHz,
CDCl ) δ 166.93, 163.34, 137.21, 136.38, 136.01, 128.88,
3
(26a/b)
128.82, 128.73, 128.40, 128.39, 128.28, 128.19, 80.34,
8
0.28, 72.7, 71.8, 71.0, 66.8, 49.9, 37.0, 17.2; HR-ESI-MS
+
+
To a 100 mL round bottom flask, thioester 19a (2.89 g,
.0 mmol, 1.0 equiv) and Pd/C (10% Pd on activated car-
bon, 500 mg, 0.1 equiv based on Pd) were added. After
(m/z): calcd for C H NO Na (M + Na ): 480.1993,
25 31 7
5
found 480.2002. For minor diastereomer 26b: [α] + 17.3 (c
1
0.3, DCM); H NMR (500 MHz, CDCl ) δ 8.21 (1 H, s),
3
agron protection of the flask, anhydrous DCM (25 mL) was
7.27–7.42 (10 H, m), 6.66 (1 H, d, J = 8.5 Hz), 6.34 (1 H,
s), 5.73 (1 H, s), 5.20 (2 H, s), 4.84 (1 H, s), 4.71 (1 H, d,
J = 11.5 Hz), 4.64 (1 H, s), 4.42 (1 H, d, J = 11.0 Hz), 4.15
(1 H, dd, J = 9.0, 4.5 Hz), 3.99 (1 H, d, J = 9.0 Hz),
3.85–3.92 (1 H, m), 3.65–3.73 (1 H, m), 3.46 (1 H, d, J =
added, and the mixture was stirred mildly. Et SiH (3.0 mL,
3
1
9 mmol, 3.8 equiv) was added dropwise during 20 min,
then the mixture was mildly stirred at r.t. for 2 h. When full
conversion was achieved, the mixture was filtered through
celite and the filtrate was concentrated under vacuum to
give crude aldehyde 20. The aldehyde was used in the next
step without further purification.
9.0 Hz), 3.15 (1 H, t, J = 8.5 Hz), 2.65 (1 H, dd, J =
1
14.0 Hz, J = 3.5 Hz), 2.54 (1 H, dd, J = 14.0 Hz, J = 9.0
2
1
2
1
3
Hz), 1.39 (3 H, d, J = 6.0 Hz); C NMR (125 MHz,
To a 50 mL round bottom flask, indium power (1.72 g,
CDCl ) δ 167.12, 162.69, 137.36, 136.74, 135.91, 128.84,
3
1
5 mmol, 3.0 equiv) was added, followed by EtOH (20
128.75, 128.58, 128.44, 128.35, 128.28, 128.19, 80.1, 75.1,
mL), benzyl bromomethylacrylate (5.15 g, 22.5 mmol, 4.5
72.8, 71.6, 70.9, 66.9, 50.9, 37.7, 17.0; HR-ESI-MS (m/z):
+
+
equiv) and sat. NH Cl solution (3 mL). The mixture was
calcd for C H NO Na (M + Na ): 480.1993, found
4
25 31 7
o
sonicated for 20 min at 50 C to generate the corresponding
480.2003.
indium reagent. This so-obtained solution of indium reagent
was added into the solution of the above crude aldehyde 20
in EtOH (10 mL) in one portion, and the mixture was stirred
at r.t. for 2 h. The reaction was quenched by sat. NaHCO3,
then dilute with ethyl acetate (500 mL). The organic layer
was separated and the aqueous layer was extract with
another 500 mL ethyl acetate. The organic layer was com-
bined and washed with 1 M HCl (aq, 200 mL), sat. NaHCO3
Benzyl (4 R,5 S,6 R,7 R,8 S)-5-acetamido-8-
(benzyloxy)-4,6,7-trihydroxy-2-
methylenenonanoate (27)
To a 50 mL round bottom flask containing compound 26a
(1.35 g, 2.95 mmol, 1.0 equiv), a cold solution of HCl (aq)
in MeOH (3%, 12.0 mL prepared from conc. HCl 1.0 mL
and MeOH 11.0 mL) was added. The reaction mixture was
(
aq, 200 mL), and brine (200 mL), and was dried over
o
anhydrous Na SO . The organic solvent was concentrated
gradually warmed from 0 C to r.t. and kept stirring for 6 h.
2
4
under vacuum and the residue was directly used in the
next step.
When full conversion was achieved as indicated by TLC,
the mixture was cooled to 0 C again and solid sodium
o
To a solution of the above residue in THF (100 mL) was
added a mixture of TBAF (1.0 M solution in THF, 15.0 mL,
bicarbonate was carefully added until the solution turned
neutral. Acetic anhydride (120 μL, 1.24 mmol, 2.0 equiv)
was added and the solution was kept stirring for 1 h. After
full conversion as indicated by TLC, the reaction was
diluted with ethyl acetate (500 mL), washed with1 M HCl
3
.0 equiv) and acetic acid (0.44 mL, 15.0 mmol, 1.5 equiv).
The reaction mixture was kept stirring for 2 h and monitored
by TLC. When full conversion was achieved, the reaction
mixture was diluted with ethyl acetate (500 mL), then was
thoroughly washed with brine (200 mL) and dried over
Na SO . The organic solvent was concentrated under
(aq, 50 mL), sat. NaHCO (aq, 50 mL), and brine (50 mL),
3
and dried over anhydrous Na SO . The organic solvent was
2
4
removed under vacuum and the residue was purified by
flash column chromatography using DCM: ethyl acetate 3:
2
4
vacuum and the residue was purified by flash column

R. Wei et al.
2
v/v as eluent to obtain compound 27 as white foam (347
166.9, 137.23, 136.5, 136.1, 128.87, 128.72, 128.61,
128.39, 128.35, 128.24, 128.20, 80.75, 80.64, 71.98, 71.89,
71.0, 66.8, 51.1, 37.0, 23.2, 17.3; HR-ESI-MS (m/z): calcd
mg, 24.5%) and DCM: ethyl acetate 1: 1 v/v as eluent to
obtain lactone 27a as white foam (686 mg, 64%). For lac-
tone 27a: [α] + 12.3 (c 0.5, DCM); H NMR (500 MHz,
1
+
+
for C H NO Na (M + Na ): 494.2149, found 494.2160.
26 33 7
CDCl ) δ 7.27–7.40 (5 H, m), 6.25 (1 H, t, J = 2.0 Hz), 6.09
3
(
1 H, d, J = 9.0 Hz), 5.67 (1 H, s), 4.69–4.75 (1 H, m), 4.70
1 H, d, J = 11.0 Hz), 4.43 (1 H, d, J = 11.0 Hz), 4.29 (1 H,
5-Acetamido-3,5,9-trideoxy-L-glycero-L-gluco-non-
2-ulosonic acid (1)
(
t, J = 7.0 Hz), 3.67–3.75 (1 H. m), 3.68 (1 H, d, J = 9.0 Hz),
3
2
.21 (1 H, t, J = 8.0 Hz), 3.06 (1 H, dt, 1 = 17.0, 2.0 Hz),
.76 (1 H, dt, J = 17.0, 3.0 Hz), 2.08 (3 H, s), 1.36 (3 H, d,
The solution of compound 27 (235 mg, 0.5 mmol) in DCM
(10 mL) and methanol (5 mL) was cooled to −78 C. The
o
1
3
J = 6.0 Hz); C NMR (125 MHz, CDCl ) δ 172.7, 169.8,
O (generated from O and carried by the flow of O ) was
3
3
2
2
1
37.5, 133.6, 128.8, 128.29, 128.15, 123.0, 79.2, 74.8,
bubbled through this solution. The color of the solution
7
2.1, 71.0, 54.1, 31.4, 23.3, 16.4; HR-ESI-MS (m/z): calcd
turned purple, which indicated the saturation of O . The
3
+
+
for C H NO Na (M + Na ): 386.1574, found 386.1581.
excess amount of O was blown off by the flow of O and
1
9
25
6
3
2
To a 50 mL round bottom flask containing lactone 27a
the purple color disappeared. To this solution, Me S (2 mL)
2
(
5
686 mg, 1.88 mmol, 1.0 equiv) was added 1 M NaOH (aq,
mL). The reaction was kept vigorous stirring for 2 h and
was added to reduce the peroxide intermediate. After 1 h
reduction at r.t., the solvent was removed under vacuum and
the residue was purified by flash column chromatography
using DCM: methanol 30: 1 v/v as eluent to obtain com-
pound 29 as white foam, which was the mixture of linear
and cyclic tautomers (177.4 mg, 75%).To a round bottom
flask containing compound 29 (109.4 mg, 0.375 mmol), Pd
monitored by TLC. When full conversion was achieved, ion
exchange resin Dowex 50 W X8 (H ) was carefully added
to neutralize the reaction. The mixture was filtered through
celite to remove the resin and a small portion of the acid 28
(
+
10 mg) was purified by HPLC for characterization. To the
aqueous solution of acid 28 was added K CO (259 mg,
(OH) /C (20% Pd on activated carbon, 50 mg) was added.
2
3
2
1
.88 mmol, 1.0 equiv). Water was removed by oil pump and
methanol (10 mL) and water (3 mL) were added to the flask.
the residue obtained was re-dissolved in DMF (5 mL).
Benzyl bromide (446 μL, 3.76 mmol, 2.0 equiv) was added
and the reaction mixture was kept stirring for 6 h. When full
conversion was achieved as indicated by TLC, the mixture
was diluted with ethyl acetate (300 mL), washed with brine
The mixture was kept stirring under 1 atm H atmosphere
for 12 h. After filtration, the solvent was removed under
vacuum and the residue was further purified by BioGel
2
column using H O as eluent. The product 1 was obtained
2
1
after lyophilization as white foam (92.2 mg, 87%). H NMR
(
50 mL), and dried over anhydrous Na SO . The organic
(500 MHz, D O) δ 4.28 (1 H, dd, J = 9.5, 2.0 Hz, H-6),
2
4
2
solvent was removed under vacuum and the residue was
purified by flash column chromatography using DCM: ethyl
acetate 3: 2 v/v as eluent to obtain compound 27 as white
foam (761.5 mg, 86%, together with previous potion, 1.10
g, 79% from 26a). For acid 28: 1H NMR (500 MHz,
4.00–4.08 (3 H, m, H-4, H-5, H-8), 3.69 (1 H, dd, J = 9.5,
7.0 Hz, H-7), 2.05–2.11 (1 H, m, H-3e), 2.05 (3 H, s,
CH CO), 1.83–1.88 (1 H, m, H-3a), 1.15 (3 H, d, J =
3
1
3
6.5 Hz, H-9); C NMR (125 MHz, D O) δ 176.7 (CH CO),
2
3
174.3 (COOH), 96.0 (C-1), 71.5 (C-7), 67.6 (C-8), 66.3 (C-
CDCl ) δ 7.28–7.38 (5 H, m), 6.76 (1 H, d, J = 10.5 Hz),
6), 65.9 (C-4), 47.9 (C-5), 32.3 (C-3), 21.7 (CH CO), 14.6
3
3
+
6
.38 (1 H, s), 5.73 (1 H, s), 4.70 (1 H, d, J = 11.0 Hz), 4.41
(C-9); HR-ESI-MS (m/z): calcd for C H NO Na (M +
1
1
19
8
+
(
1 H, d, J = 11.0 Hz), 4.30 (1 H, t, J = 7.0 Hz), 4.12 (1 H, d,
Na ): 316.1003, found 316.1009.
J = 9.0 Hz), 3.88 (1 H, dd, J = 9.0, 1.0 Hz), 3.68–3.73 (1 H,
m), 3.10 (1 H, t, J = 9.0 Hz), 2.55 (1 H, dd, J = 14.0, 7.5
Hz), 2.43 (1 H, dd, J = 14.0, 6.0 Hz), 2.17 (3 H, s), 1.40 (3
H, d, J = 5.5 Hz). No carbon spectrum recorded due to the
unstability of the acid.
Benzyl 5-acetamido-8-O-benzyl-2,4,7-tri-O-acetyl-
3,5,9-trideoxy-L-glycero-L-gluco-2-
nonulopyranosonate (30)
1
For Benzyl ester 27: [α] + 19.96 (c 0.3, DCM); H NMR
To the solution of compound 29 (112 mg, 0.378 mmol) in
(
400 MHz, CDCl ) δ 7.27–7.40 (10 H, m), 6.38 (1 H, d, J =
pyridine (5 mL), Ac O (2 mL) and DMAP (3 mg, 0.02
3
2
9
.2 Hz), 6.30 (1 H, d, J = 0.8 Hz), 5.65 (1 H, s), 5.27 (1 H,
mmol, 0.06 equiv) were added sequentially. The mixture
was kept stirring for 3 h. The mixture was concentrated
under vacuum and the residue was dissolved in ethyl acetate
(100 mL). The solution was washed with 1 M HCl (aq,
br), 5.21 (1 H, d, J = 12.4 Hz), 5.17 (1 H, d, J = 12.4 Hz),
4.78 (1 H, s), 4.70 (1 H, d, J = 11.2 Hz), 4.40 (1 H, d, J =
11.2 Hz), 4.25 (1 H, t, J = 6.8 Hz), 4.06 (1 H, d, J = 9.2 Hz),
3.09 (1 H, s), 3.79 (1 H, dd, J = 8.8, 0.8 Hz), 3.62–3,71
20 mL), sat. NaHCO (aq, 20 mL), and brine (20 mL) and
3
(
7
(
1 H, m), 3.06 (1 H, t, J = 8.8 Hz), 2.55 (1 H, dd, J = 14.0,
.6 Hz), 2.41 (1 H, dd, J = 14.0, 6.0 Hz), 2.11 (3 H, s), 1.39
was dried over anhydrous Na SO . The organic solvent was
removed under vacuum and the residue was purified by
silica gel flash chromatography using n-hexane: ethyl
2
4
13
3 H, d, J = 6.0 Hz); C NMR (100 MHz, CDCl ) δ 172.9,
3

De novo synthesis of novel bacterial monosaccharide fusaminic acid
acetate 2.5: 1 v/v as eluent to obtain acetate 30 as white
foam (183 mg, 83%). H NMR (0.9: 1 mixture of two
(1 H, d, J = 12.0 Hz, PhCH O), 4.57 (1 H, d, J = 11.0 Hz,
2
1
PhCH O), 4.48 (1 H, d, J = 11.0 Hz, PhCH O), 4.14 (1 H,
2
2
anomers, peaks selected for the major anomer, 500 MHz,
dt, J = 7.5, 1.0 Hz, H-5), 3.89 (1 H, qd, J = 6.5, 4.5 Hz, H-
8), 2.68 (1 H, dd, J = 16.0, 2.0 Hz, H-3e), 2.32 (3 H, s,
SC H CH ), 2.20 (1 H, dd, J = 16.0, 3.5 Hz, H-3a), 2.18
CDCl ) δ 7.27–7.39 (10 H, m), 6.20 (1 H, d, J = 9.0 Hz),
3
,
5
5
.26 (1 H, dd, J = 9.0, 2.5 Hz), 5.20 (1 H, d, J = 12.0 Hz),
.13 (1 H, d, J = 12.5 Hz), 5.02 (1 H, q, J = 3.5 Hz), 4.80
6
4
3
(3 H, s, CH CO), 2.08 (3 H, s, CH CO), 1.71 (3 H, s,
3
3
1
3
(1 H, dd, J = 9.0, 2.0 Hz), 4.56 (1 H, d, J = 11.5 Hz), 4.45
(1 H, d, J = 11.5 Hz), 4.16 (1 H, dt, J = 9.0, 2.0 Hz), 3.87
(1 H, qd, J = 6.5, 3.5 Hz), 2.59 (1 H, dd, J = 15.5, 2.5 Hz),
CH CO), 1.30 (3 H, d, J = 6.5 Hz, H-9); C NMR (125
3
MHz, CDCl ) δ 170.4, 170.0, 169.8, 167.9, 139.6, 138.1,
3
135.3, 134.9, 129.7, 128.7, 128.6, 128.4, 127.9, 127.5,
89.3, 74.1, 71.9, 71.3, 68.5, 67.6, 46.1, 32.9, 27.2, 22.9,
21.7, 21.4, 21.0, 15.8; HR-ESI-MS (m/z): calcd for
2
.32 (2 H, dd, J = 15.0, 3.5 Hz), 2.09 (3 H, s), 2.03 (3 H, s),
1
1
.96 (3 H, s), 1.83 (3 H, s), 1.17 (3 H, d, J = 6.5 Hz); H
+
+
NMR (0.9: 1 mixture of two anomers, peaks selected for the
C H NO SNa (M + Na ): 686.2394, found 686.2407.
36 41 9
minor anomer, 500 MHz, CDCl ) δ 7.27–7.39 (9 H, m),
3,
Acknowledgements This work was supported by the Research Grants
Council of Hong Kong (17305615, 17309616, C5026–16G) and the
University Grants Committee of Hong Kong (Grant AoE/P-705/16).
6
5
.20 (0.9 H, d, J = 9.0 Hz), 5.22 (0.9 H, d, J = 12.5 Hz,),
.18 (0.9 H, dd, J = 9.0, 2.5 Hz), 5.13 (0.9 H, d, J = 12.5
Hz), 4.92–4.94 (0.9 H, m), 4.63 (0.9 H, dd, J = 9.0, 2.0 Hz),
4
4
.57 (0.9 H, d, J = 11.5 Hz), 4.49 (0.9 H, d, J = 11.5 Hz),
.20 (1 H, dt, J = 9.0, 2.0 Hz), 3.78 (0.9 H, qd, J = 6.5, 2.5
Compliance with ethical standards
Hz), 2.40 (0.9 H, dd, J = 16.0, 1.5 Hz), 2.11 (2.7 H, s), 2.04
Conflict of interest The authors declare that they have no conflict of
(
1
2.7 H, s), 1.99 (0.9 H, dd, J = 16.0, 4.0 Hz), 1.93 (2.7 H, s),
.92 (2.7 H, s), 1.24 (d, J = 6.5 Hz, 2.7 H); C NMR (125
interest.
13
Publisher’s note: Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional affiliations.
MHz, CDCl ) δ 170.46, 170.19, 170.06, 169.91, 169.57,
3
1
1
1
7
6
2
69.16, 168.55, 167.65, 168.42, 167.36, 138.53, 138.46,
34.87, 134.81, 128.89, 128.84, 128.80, 128.70, 128.54,
28.45, 128.44, 128.08, 128.03, 127.79, 127.67, 96.3, 95.8,
5.0, 74.1, 71.5, 71.23, 71.05, 70.7, 70.2, 68.20, 68.16,
7.8, 67.3, 45.05, 44.60, 30.88, 29.89, 23.32, 23.11, 21.49,
1.25, 21.00, 20.97, 20.73, 20.58, 15.5, 14.3; HR-ESI-MS
References
1
. Han YW. Fusobacterium nucleatum: a commensal-turned patho-
gen. Curr Opin Microbiol. 2015;23:141–7.
2. Moore WEC, Moore LVH. The bacteria of periodontal diseases.
+
+
Peridontol. 1994;5:66–7.
(
m/z): calcd for C H NO Na (M + Na ): 622.2259,
31 37 11
3
. Griffen AL, et al. Distinct and complex bacterial profiles in human
found 622.2271.
periodontitis and health revealed by 16S pyrosequencing. ISME J.
2
012;6:1176–85.
4
-Methylphenyl 7-acetamido-8-benzyl-4,7-di-O-
4. Loozen G, et al. Inter-bacterial correlations in subgingival bio-
films: a large-scale survey. J Clin Periodontol. 2014;41:1–10.
acetyl-3,5,9-trideoxy-β-thiofusaminoside (31)
5
. Saygun I, et al. Salivary infectious agents and periodontal disease
status. J Periodontal Res. 2011;46:235–9.
To a 25 mL round bottom flask, acetate 30 (183 mg, 0.31
mmol, 1.0 equiv) and 4-toluenethiol (234 mg, 1.88 mmol,
6
. Feng X, et al. Detection of eight periodontal microorganisms and
distribution of Porphyromonas gingivalis fimA genotypes in chi-
nese patients with aggressive periodontitis.
014;85:150–9.
J Periodontol.
6
.0 equiv) were added. Anhydrous DCM (6.0 mL) was
2
added under argon, and the concentration of 30 was kept at
7
8
. Liu P, et al. Detection of Fusobacterium nucleatum and fadA
adhesin gene in patients with orthodontic gingivitis and non-
orthodontic periodontal inflammation. PLoS ONE. 2014;9:
e85280.
. Yang NY, Zhang Q, Li JL, Yang SH, Shi Q. Progression of
periodontal inflammation in adolescents is associated with
increased number of Porphyromonas gingivalis, Prevotella inter-
media, Tannerella forsythensis, and Fusobacterium nucleatum. Int
J Paediatr Dent. 2014;24:226–33.
o
5
0 mM. The mixture was cooled to 0 C, then BF ·Et O
3 2
(
77 μL, 0.62 mol, 2.0 equiv) was added dropwise. The
o
mixture was then kept stirring at 0 C to r.t. for 16 h. The
reaction was quenched by sat. NaHCO3 (aq), and the
organic phase was dried over anhydrous Na SO . The sol-
vent was removed under vacuum and the residue was pur-
ified by silica gel flash chromatography using n-hexane:
ethyl acetate 4:1 v/v as eluent to obtain thioglycoside 31 as
yellow foam (127.4 mg, 62%) and characterized as β
2
4
9
. Kistler JO, Booth V, Bradshaw DJ, Wade WG. Bacterial com-
munity development in experimental gingivitis. PLoS ONE.
2
013;8:e71227.
1
anomer (JC1, H3a = 6.4 Hz). [α] + 10.85 (c 0.7, DCM); H
NMR (500 MHz, CDCl ) δ 7.26–7.35 (10 H, m, ArH),
10. Didilescu AC, et al. Investigation of six selected bacterial species
in endo-periodontal lesions. Int Endod J. 2012;45:282–93.
1. Fujii R, et al. Characterization of bacterial flora in persistent
3,
1
7
6
.15–7.20 (ArH, m, 2 H), 7.02 (2.0 H, d, J = 8.0 Hz, ArH),
.31 (1 H, d, J = 8.0 Hz, NH), 5.23 (1 H, dd, J = 7.5, 4.5
apical periodontitis lesions. Oral Microbiol Immunol. 2009;24:
5
02–5.
Hz, H-7), 5.11 (1 H, dd, J = 7.0, 2.0 Hz, H-6), 4.98–5.02
1 H, m, H-4), 4.86 (1 H, d, J = 12.0 Hz, PhCH O), 4.83
12. Siqueira JF Jr, Rocas IN, Paiva SS, Magalhaes KM, Guimar-
aesPinto T. Cultivable bacteria in infected root canals as identified
(
2

R. Wei et al.
by 16S rRNA gene sequencing. Oral Microbiol Immunol.
007;22:266–71.
synthesis of pseudaminic acid. J Am Chem Soc. 2017;139:
13420–8.
2
1
3. Han YW. Fusobacterium nucleatum infection with host cells. In:
Kolenbrander PE, editor. Oral Microbial Communities: Genomic
Inquiry and Interspecies Communication. 1st edn. Washington,
DC: ASM Press; 2011. p. 221–32.
4. Han YW, et al. Term stillbirth caused by oral Fusobacterium
nucleatum. Obstet Gynecol. 2010;115:442–5.
31. Rotstein BH, Winternheimer DJ, Yin LM, Deber CM, Yudin AK.
Thioester-isocyanides: versatile reagents for the synthesis of
cycle-tail peptides. Chem Commun. 2012;48:3775–7.
32. Nahm S, Weinreb SM. N-methoxy-N-methylamides as effective
acylating agents. Tetrahedron Lett. 1981;22:3815–8.
33. Nakata T, Tanaka T, Oishi T. Stereoselective reduction of a-
hydroxy ketones. Tetrahedron Lett. 1983;24:2653–6.
34. Hoppe D, Schollkopf U. Ethyl 2-oxazoline-5-carboxylate from
ethyl isocyanoacetate and carbonyl compounds. Angew Chem Int
Ed. 1970;9:300–1.
1
1
5. Han YW, Shen T, Chung P, Buhimschi IA, Buhimschi CS.
Uncultivated bacteria as etiologic agents of intra-amniotic
inflammation leading to preterm birth.
009;47:38–47.
J Clin Microbiol.
2
1
1
6. Bohrer JC, Kamemoto LE, Almeida PG, Ogasawara KK. Acute
chorioamnionitis at term caused by the oral pathogen Fuso-
35. Ito Y, Matasuura T, Saegusa T. ZnCl2 and CuCl promoted aldol
reactions of isocyanoacetate with α,β-unsaturated carbonyl com-
pounds. Tetrahedron Lett. 1985;26:5781–4.
36. Kisanga P, Ilankumaran P, Verkade JGP. RNCH2CH2)3N-
catalyzed diastereoselective synthesis of ozazolines. Tetrahedron
Lett. 2001;42:6263–6.
bacterium nucleatum. Hawaii
012;71:280–1.
7. Dixon NG, Ebright D, Defrancesco MA, Hawkins RE. Orogenital
contact: cause of chorioamnionitis? Obstet Gynecol.
994;84:654–5.
J
Med Public Health.
2
a
1
37. Zhang LJ, et al. Tandan Michael addition/intramolecular iso-
cyanide [3+2] cycloaddition: highly diastereoselective one pot
synthesis of fused oxazolines. Chem Commun. 2010;46:3357–9.
38. Matsumoto K, Ozaki Y, Suzuki M, Miyoshi M. A stereoselective
synthesis of threo-threonine reaction of isocyanoacetate with
acetaldehyde. Agr Biol Chem Tokyo. 1976;40:2045–50.
39. Ito Y, Sawamura M, Hayashi T. Catalytic asymmetric aldol
reaction: reaction of aldehydes with isocyanoacetate catalyzed by
a chiral ferrocenylphosphine-gold(I) complex. J Am Chem Soc.
1986;108:6405–6.
40. Evans DA, Janey JM, Magomedov N, Tedrow JS. Chiral salen-
aluminum complexes as catalyst for enantioselective aldol reac-
tions of aldehydes and 5-alkoxyozazolines: an efficient approach
to the asymmetric synthesis of syn and anti β-hydroxy-α-amino
acid derivatives. Angew Chem Int Ed. 2001;40:1884.
1
1
8. Marchesi JR, et al. Towards the human colorectal cancer micro-
biome. PLoS ONE. 2011;6:e20447.
9. Kostic AD, et al. Genomic analysis identifies association of
Fusobacterium with colorectal carcinoma. Genome Res. 2012;22:
2
92–8.
2
0. Rubinstein MR, et al. Fusobacterium nucleatum promotes color-
ectal carcinogenesis by modulating E-cadherin/β-catenin signaling
via its FadA adhesin. Cell Host Microbe. 2013;14:195–206.
1. Temoin S, et al. Identification of oral bacterial DNA in synovial
fluid of patients with arthritis with native and failed prosthetic
joints. J Clin Rheumatol. 2012;18:117–21.
2
2
2. Brook I. Fusobacterial infections in children. Curr Infect Dis Rep.
2
013;15:288–94.
2
3. Williams MD, Kerber CA, Tergin HF. Unusual presentation of
Lemierre’s syndrome due to Fusobacterium nucleatum. J Clin
Microbiol. 2003;41:3445–8.
41. Adinolfi M, Barone G, Guariniello L, Iadonisi A. Facile cleavage
of carbohydrate benzyl ethers and benzylidene acetals using the
NaBrO3 Na S O reagent under two-phase conditions. Tetra-
2
2
4. Sparks Stein P, et al. 3rd. Serum antibodies to periodontal
pathogens are a risk factor for Alzheimer’s disease. Alzheimers
Dement. 2012;8:196–203.
5. Xu M, et al. FadA from Fusobacterium nucleatum utilizes both
secreted and nonsecreted forms for functional oligomerization for
attachment and invasion of host cells. J Biol Chem. 2007;
2
2
4
hedron Lett. 1999;40:8439–41.
42. Fukuyama T, Lin SC, Li L. Facile reduction of ethyl thiol esters to
aldehydes: application to a total synthesis of (+)-neothramycin A
methyl ether. J Am Chem Soc. 1990;112:7050–1.
43. Mirza-Aghayan M, Boukherroub R, Bolourtchian M. Palladium-
catalyzed protection of alcohols and cleavage of triethylsilyl
ethers. J. Organomet. Chem. 2005;9:2372–5.
44. Sheehan JC, Yang DH. The use of N-formamide acids in peptide
synthesis. J Am Chem Soc. 1958;80:1154–8.
45. Shen ZL, Wang SY, Chok YK, Xu YH, Loh TP. Organoindium
reagents: the preparation and application in organic synthesis.
Chem Rev. 2013;113:271–401.
2
82:25000–9.
2
2
2
6. Fardini Y, et al. Fusobacterium nucleatum adhesin FadA binds
vascular endothelial cadherin and alters endothelial integrity. Mol
Microbiol. 2011;82:1468–80.
7. Onoue S, et al. Serum antibodies of periodontitis patients com-
pared to the lipopolysaccharides of Porphyromoas gingivalis and
Fusobacterium nucleatum. Microbiol Immunol. 2003;47:51–5.
8. Vinogradov E, Michael FS, Cox AD. The structure of the LPS O-
chain of Fusobacterium nucleatum strain 25586 containing two
novel monosaccharides, 2-acetamido-2,6-dideoxy-L-altrose and a
46. Matthies S, Stallforth P, Seeberger PH. Total synthesis of legio-
naminic acid as basis for serological studies. J Am Chem Soc.
2015;137:2848–51.
5
-acetimidoylamino-3,5,9-trideoxy-gluconon-2-ulosonic
acid.
47. Lee YJ, Kubota A, Ishiwata A, Ito Y. Synthesis of pseudaminic
acid, a unique nonulopyranoside derived from pathogenic bacteria
through 6-deoxy-altdiNAc. Tetrahedron Lett. 2011;19:418–21.
48. Knirel YA, Shashkov AS, Tsvetkov YE, Jasson PE, Zahringer U.
5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acid in bacteria
glycopolymers: chemistry and biology. Adv Carb Chem Biochem.
2003;58:371–417.
Carbohydr Res. 2017;440-441:10–5.
2
9. Zunk M, Kiefel MJ. The occurrence and biological significance of
the a-keto-sugars pseudaminic acid and legionaminic acid within
pathogenic bacteria. RSC Adv. 2014;4:3413–21.
0. Liu H, Zhang YF, Wei RH, Andolina G, Li XC. Total synthesis
of Pseudomonas aeruginosa 1244 pilin glycan via de novo
3