Stereoselective glycal fluorophosphorylation: Synthesis of ADP-2-fluoroheptose, an inhibitor of the LPS Biosynthesis

Article abstract of DOI:10.1002/chem.200801279

Heptosides are found in important bacterial glycolipids such as lipopolysaccharide (LPS), the biosynthesis of which is targeted for the development of novel antibacterial agents. This work describes the synthesis of a fluorinated analogue of ADP-L-glycero-β-D-manno-heptopyranose, the donor substrate of the heptosyl transferase WaaC, which catalyzes the incorporation of this carbohydrate into LPS. Synthetically, the key step for the preparation of ADP-2F-heptose is the simultaneous and stereoselective installation of both the fluorine atom at C-2 and the phosphoryl group at C-1 through a selectfluor-mediated (selectfluor= 1-chloromethyl-4-fluorodiazoniabicyclo[2.2.2] octane bis(triflate)) electrophilic addition/nucleophilic substitution involving a heptosylglycal. Therefore, we detail in this article 1) the stereoselective preparation of the key intermediates heptosylglycals, 2) the development of a new fluorophosphorylation procedure allowing an excellent β-gluco stereoselectivity with "all-equatorial" glycals, 3) the synthesis of the target ADP-2F-heptose, and 4) some comments on the contacts observed between the fluorine atom of the final molecule and the protein in the crystallographic structure of heptosyltransferase WaaC.

Full text of DOI:10.1002/chem.200801279

DOI: 10.1002/chem.200801279
Stereoselective Glycal Fluorophosphorylation: Synthesis ofADP-2-
fluoroheptose, an Inhibitor of the LPS Biosynthesis
Hirofumi Dohi,[b] RØgis PØrion,[b] Maxime Durka,[a] Michael Bosco,[b] Yvain RouØ,[b]
FranÅois Moreau,[c] Sylvestre Grizot,[d] Arnaud Ducruix,[d] Sonia Escaich,[c] and
StØphane P. Vincent*[a]
Abstract: Heptosides are found in im-
portant bacterial glycolipids such as lip-
opolysaccharide (LPS), the biosynthe-
sis of which is targeted for the develop-
ment of novel antibacterial agents. This
work describes the synthesis of a fluori-
nated analogue of ADP-l-glycero-b-d-
manno-heptopyranose, the donor sub-
strate of the heptosyl transferase
WaaC, which catalyzes the incorpora-
tion of this carbohydrate into LPS.
Synthetically, the key step for the prep-
aration of ADP-2F-heptose is the
C
fore, we detail in this article 1) the ste-
reoselective preparation of the key in-
termediates heptosylglycals, 2) the de-
velopment of
a
new fluorophos-
phorylation procedure allowing an ex-
cellent b-gluco stereoselectivity with
“all-equatorial” glycals, 3) the synthesis
of the target ADP-2F-heptose, and 4)
some comments on the contacts ob-
served between the fluorine atom of
the final molecule and the protein in
the crystallographic structure of hepto-
syltransferase WaaC.
Introduction
LPS is an amphipathic molecule that can be decomposed
into three main substructures: lipid A, the oligosaccharide
core and the O-antigen. The oligosaccharide core can be di-
vided into two parts: the inner core is formed of at least one
molecule of 3-deoxy-a-d-manno-oct-2-ulopyranosonic acid
(Kdo) and two molecules of l-glycero-a-d-manno-heptopyr-
anose (heptose), and the outer core is composed of hexoses.
Lipid A and one Kdo is the minimal structure for maintain-
ing cell viability. Gram-negative bacteria that lack heptose
display the deep-rough phenotype[3] and show a reduction in
outer membrane protein content, an increased sensitivity to-
wards detergents or hydrophobic antibiotics, and are much
more susceptible to phagocytosis by macrophages.[4] There-
fore, the heptosyltransferases implied in LPS biosynthesis
represent attractive targets, the inhibition of which could at-
tenuate the virulence of diverse bacterial strains.
Lipopolysaccharide (LPS) is a key component of the outer
membrane of Gram-negative bacteria.[1] The mortality of
many infectious diseases is closely related to the amount of
circulating LPS endotoxins found in patient sera.[2]
[a]M. Durka, Dr. S. P. Vincent
University of Namur (FUNDP)
DØpartement de Chimie
Laboratoire de Chimie Bio-Organique
rue de Bruxelles 61, 5000 Namur (Belgium)
Fax : (+32)81-724-517
E-mail: stephane.vincent@fundp.ac.be
[b]Dr. H. Dohi, Dr. R. PØrion, Dr. M. Bosco, Dr. Y. RouØ
Ecole Normale SupØrieure, DØpartement de Chimie
Institut de Chimie MolØculaire (FR 2769)
In a more general perspective, the discovery of glycosyl-
transferase (GT) inhibitors[5] as well as the understanding of
their intimate mechanism still represent challenging
tasks.[6,7] To date, one of the most general class of GT inhibi-
tors is the family of NDP-2-fluoro-sugars (NDP=nucleoside
diphosphate), which are analogues of the donor substrates
(NDP-sugars).[7–10] NDP-2-fluoro-sugars generally display
low micromolar inhibition levels in the range of the Km of
UMR 8642: CNRS-ENS-UPMC Paris 6, 24 rue Lhomond
75231 Paris Cedex 05 (France)
[c]Dr. F. Moreau, Dr. S. Escaich
Mutabilis, 102
route de Noisy F-93230 Romainville (France)
[d]Dr. S. Grizot, Prof.Dr. A. Ducruix
Laboratoire de Cristallographie et RMN Biologiques
UniversitØ Paris Descartes, UMR 8015 CNRS
4, Avenue de lꢀObservatoire F-75270 Paris cedex 06 (France)
9530
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FULL PAPER
GTꢀs donor substrates.[7] Interestingly, they are also valuable
tools for co-crystallisation experiments with GTs, since they
are both competitive inhibitors and very close analogues of
their substrates. To date, the structures of six GTs in com-
plex with NDP-2F-sugars have been resolved.[11,12] It is
worth noting that the co-crystallization of glycosyltransferas-
es with NDP-sugar analogues revealed substrate-induced
conformational changes of the protein. These results are ex-
tremely important, since they provide the binding mode and
the conformation of the donor within the catalytic pocket,
which can facilitate the design of inhibitors and the under-
standing of the mechanism.
mainly using stereoselective Grignard additions or osmium
dihydroxylation.[15] In contrast, the synthesis of glucosylhep-
toses has been much less investigated.[16,17] Thus, we first ex-
plored the stereoselective preparation of l-glycero-d-gluco-
heptoses from a key olefin intermediate 4 derived from d-
glucose. Alcohol 3 was prepared in 80% yield from com-
mercial methyl a-d-gluco-pyranoside by installation of tri-
AHCTREiUNG sopropylsilyl (TIPS) group at O-6 position, followed by a
For Gram-negative bacteria, the donor substrate of hepto-
syltransferases is ADP-l-glycero-b-d-manno-heptose 1, the
Scheme 1. Reagents and conditions: a) TIPSCl, Im, DMF, RT; BnBr,
NaH, DMF, RT; TBAF, THF RT, 80% for 3 steps; b) (COCl)2, DMSO,
NEt3, CH2Cl2, ꢀ788C!08C; Ph3CH3P+, Brꢀ, nBuLi, THF, 08C!RT,
72% for two steps; c) OsO4, NMO, acetone, H2O, 0 8C!RT, 92 %; d)
Ac2O, Py, RT, quant; e) mCPBA, CH2Cl2, 08C!RT, 87%; f) CsOAc,
[18]crown-6, DMF, 1008C; Ac2O, Py, RT, 84% for 2 steps.
anomeric configuration of which has been recently demon-
strated by Kosma et al.[13] To obtain a low-micromolar inhib-
itor that will be used to develop and calibrate a high-
throughput inhibition assay against WaaC, the first heptosyl
transferase of LPS biosynthesis, we designed and synthe-
sized molecule 2, the fluorinated analogue of the bacterial
heptosyltransferases donor substrate. Moreover, we have re-
cently reported the crystallographic structure of heptosyl-
transferase WaaC in complex with 2.[12]
per-O-benzylation and a desilylation (Scheme 1). Swern oxi-
dation of 3 afforded an intermediate aldehyde that was im-
mediately subjected to a Wittig reaction to afford the olefin
4 in 72% yield. Treatment of olefin 4 with OsO4 (2.5 mol%)
and N-methylmorpholine-N-oxide (NMO) at room tempera-
ture furnished diol 5 in 92% yield as a 9:1 mixture of two
diastereomers. Asymetric dihydroxylations were also tested
but without success: both ADmix-a and ADmix-b[18] gave
poorer yields and lower diastereoselectivities than OsO4.
The separation of the epimeric diols 5 being difficult, the
mixture was O-peracetylated then separated by standard
silica gel chromatography to afford gluco-heptoses 6d and
6l.
Synthetically, the key step for the preparation of 2 is the
simultaneous and stereoselective installation of both fluo-
rine atom at C-2 and the phosphoryl group at C-1 through a
selectfluor-mediated
fluorodiazoniabicyclo
(selectfluor=1-chloromethyl-4-
[2.2.2]octane bis(triflate)) electrophilic
A
ACHTREUNG
addition/nucleophilic substitution involving a heptosylgly-
cal.[14] Therefore, we detail in this article 1) the stereoselec-
tive preparation of the key intermediates heptosylglycals, 2)
the development of a new fluorophosphorylation procedure
allowing an excellent b-gluco stereoselectivity with “all-
equatorial” glycals, 3) the synthesis of the target ADP-2F-
heptose 2, and 4) some comments on the contacts observed
between the fluorine atom of 2 and the protein in the crys-
tallographic structure of heptosyltransferase WaaC in com-
plex with 2.
Assignment ofthe stereochemistry at C-6 : The stereochem-
istry at C-6 of each diastereomer was determined by com-
parison with analytical data of related gluco-heptosides
found in the literature.[17] Strengthening this stereochemical
assignment by standard X-ray crystallography was unfortu-
nately unsuccessful, since all attempts to obtain monocrys-
tals of heptoses 6d and 6l, or even intermediates 7 to 15,
failed. To our delight, we finally obtained suitable mono-
crystals of final-ADP-2F-heptose 2 in complex with the hep-
tosyl-transferase WaaC (Figure 1), thus demonstrating the l
Results and Discussion
Synthesis of l-heptosylglycals: Due to their involvement in
the LPS biosynthesis, several synthetic procedures for 6-d-
and 6-l-glycero-mannosylheptoses have been developed
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S. P. Vincent et al.
Scheme 2. Reagents and conditions: a) TBDMSCl, DMAP, Py, CH2Cl2,
08C!RT, 91 %; b) Tf2O, Py, CH2Cl2, ꢀ408C!RT; CsOAc, 18-crown-6,
PhMe, ultrasonication, 64%.
Figure 1. Structure of heptoside 2 in the active site of heptosyl transferase
WaaC demonstrating the l configuration at C-6 (red: oxygen; blue: nitro-
gen; light blue: fluorine). The contacts between the fluorine atom and
the protein (imidazole ring of His266 and peptidic backbone) are also
represented.
Scheme 3. Reagents and conditions: a) H2SO4, Ac2O, CHCl3, 08C!RT,
82%; b) HBr, AcOH, Ac2O, CH2Cl2, RT; Zn, CuSO4, AcONa, AcOH,
H2O, RT, 91% for 2 steps; c) Na, MeOH, RT; PivCl, DMAP, Py, RT,
82% for 2 steps; d) Na, MeOH, RT; TBDMSCl, Im, DMF, 08C!RT,
95% for 2 steps.
configuration of 2, and therefore the stereochemistry of all
intermediate molecules 6 to 15.[12]
Diastereoselective fluorophosphorylation of l-heptosyl gly-
cals: The procedure developed by Wong et al. was followed
for the first attempts of fluorophosphorylations of glycals 11
to 13 (Scheme 4 and Table 1, entries 1–3).[14] Although the
products could be detected in each case (by 31P and
19F NMR spectroscopy), they could not be isolated in pure
form due to unexpected side reactions. Even performed in a
stepwise fashion (selectfluor addition then substitution by
dibenzyl phosphate),[14] these conditions seemed too harsh
for heptosylglycals 11 to 13. The complex NMR spectra of
the crude reaction mixtures strongly suggested the forma-
tion of several diastereomers contaminated by fluorinated
side products. In addition, the fluorophosphorylations of
“all-equatorial” glycals usually suffer from low-to-moderate
diastereoselectivities at both C-2 and anomeric positions
(see discussion below): four diastereomers are therefore ex-
pected, thus complicating both the interpretation of NMR
Optimization ofthe l selectivity: Thus, the 9:1 d diastereo-
selectivity of the dihydroxylation of 5 follows Kishiꢀs
rules.[19] To obtain a better l diastereoselectivity, olefin 4
was subjected to mCPBA to afford epoxides 7 in 87% yield
as an inseparable 2.3:1 mixture. Nucleophilic opening of 7
with cesium acetate in presence of acetic anhydride yielded
6 with a 1:2.3 diastereoselectivity in favor of the l diastereo-
isomer.
To improve the overall yield in l-glycero-heptose 6l, we
then developed an epimerization procedure of diol
5
(Scheme 2). The mixture of diols 5 was first selectively pro-
tected as a silylated ether 8 in 91% yield, which was treated
with trifluoromethanesulfonic anhydride followed by a SN2
substitution with cesium acetate to afford pure silyl acetate
9l in 64% isolated yield. The two diastereoisomers 9l and
9d were independently transformed into 6l and 6d by a
simple desilylation followed by
an acetylation to demonstrate
their stereochemistry at C-6.
Synthesis ofheptosylglycals
:
One-pot deprotection of all
protective groups and O-pera-
cetylation of 9l (or 6l) with
acetic anhydride and sulfuric
acid in chloroform gave the O-
peracetylated heptopyranose 10
in 82% yield (Scheme 3). Thus,
a series of l-heptosylglycals 11–
13 could be efficiently prepared
by using a known zinc-mediated
glycal formation,[20] followed by
protective group manipulations.
Scheme 4. Fluorophosphorylation of glycals (see Table 1).
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Stereoselective Glycal Fluorophosphorylation
FULL PAPER
Table 1. Fluorophosphorylation of glycals (see Scheme 4).[a]
the reaction in the presence of 2,6-di-tert-butylpyridine
(entry 5), the temperature could be lowered to 608C result-
ing in a significant improvement of the b-gluco selectivity
compared to standard conditions (entry 4), with comparable
yields.
Glycal Phosphoryl-
ating agent
T
t
Yield Products
[%][c] a:b:c:d[d]
[8C][b] [h]
[e]
[e]
[e]
[e]
[e]
[e]
1
2
3
4
5
6
7
8
9
11
12
13
16
16
16
16
18
17
N
90
90
90
90
2
2
2
–
–
–
–
–
–
We anticipated that the temperature of the phosphoryla-
tion step could be further lowered if the nucleophilicity of
the phosphate was increased. Therefore, we employed the
sodium salt of dibenzyl phosphate in presence of [15]crown-
5 ether (15C5) and decreased the temperature of the reac-
tion. With this new procedure (entry 6), we could observe
that, starting from the same glucal 16, the yield and the ste-
reoselectivity were both improved at 608C. Lowering the
temperature to 458C (entry 7) yielded an optimized b-gluco/
a-manno 9:1 selectivity. Surprisingly, when benzylated
glucal 18[23] was used under the same conditions (entry 8),
the same global yield in fluorophosphates was obtained, but
the four diastereomers were generated. These stereoisomers
could not be separated, but their relative configurations
1.5 40
19 0:3:2:0
19 0:4:1:0
19 0:6:1:0
19 0:9:1:0
21 2:7:10:1
20 0:1:0:0
14 0:93:7:0
15 6:94:0:0
12
12
36
120
48
16
45
61
63
65
66
58
51
60
45
45
45
60
45
10 12
11 13
48
[a]Selectfluor and glycal were reacted first at room temperature; the
phosphorylating reagent was then added after disappearance of the
glycal and heated. [b]Temperature of the phosphorylation step. [c]Isolat-
ed yield. [d]Assessed by 1H, 19F and 31P NMR spectroscopy a: a-gluco b:
b-gluco c: a-manno d: b-manno. [e]Complex mixtures of non-separable
products and side products. [f]2,6-Di- tbutylpyridine. [g]In presence of
[15]crown-5.
1
could be assessed by H and 19F NMR analysis. On the other
data and the purification step. Given these unexpected diffi-
culties we decided to modify and optimize the fluorophos-
phorylation experimental procedure.
hand, silylated glucal 17 yielded the b-gluco-fluorophos-
phate 20b as a single diastereomer in 66% isolated yield
(entry 9). To our knowledge, this level of diastereoselectivity
is the highest reported to date in the literature for “all-equa-
torial” glycals. In this last case, the starting glucal 17 was to-
tally consumed. Inspection of 31P and 19F NMR spectra of
the crude reaction mixture clearly indicated that the inter-
mediate adduct between selectfluor and glycal 17 (such as
22 or 23, Scheme 5) was still present when the reaction was
stopped. From this methodological study, it can be conclud-
ed that using sterically demanding protective groups on all-
equatorial glycals and performing the phosphorylation step
at moderate temperatures give rise to good to excellent b-
gluco selectivities. In all the cases (Table 1 entries 4–9), in-
cluding the less selective ones (entries 4 and 8), the 1,2-trans
products (b-gluco or a-manno) are always produced in sig-
nificantly higher ratio than the 1,2-cis products (a-gluco and
b-manno). As illustrated in Scheme 5, the b-stereoselectivity
may be rationalized by invoking 1) a syn-addition of select-
fluor from the a-face, as demonstrated by Wong et al.,[14]
yielding intermediate adducts 22 (in a 1C4 conformation)
When glycals bear an axial or a pseudo-axial group, the
addition of selectfluor is highly diastereoselective: the mech-
anism of selectfluor attack upon the glycal in the first step
occurs through a syn-addition, from the opposite face of the
axial group, for steric reasons.[9,21] For glycals bearing only
equatorial groups, mixtures of epimers at C-2 are always
formed (manno-configured when the F is axial, gluco- when
equatorial).[8,21,22] The diastereoselectivity also depends on
the protective group pattern of the glycal: increasing the
steric hindrance of the protective groups should influence
the gluco/manno selectivity. This is the reason why we ex-
plored the fluorophosphorylation of heptosylglycals bearing
pivaloyl (Piv, 12) and tert-butyldimethylsilyl groups (TBS,
13).
Heptosylglycals belong to the family of “all-equatorial”
glycals for which the control of the manno/gluco and the a/b
selectivities remains a problem. We reasoned that better
yields and diastereoselectivities should be obtained if the re-
action could be performed at lower temperature. The fluo-
rophosphorylation of glycals re-
4
and/or 23 (in a C1 conformation), and 2) a nucleophilic sub-
quires a stepwise procedure in
which the fluorination is first
conducted at room tempera-
ture, the dialkylphosphate is
then added and heated at 908C
(entry 4). To optimize a new
procedure, we selected known
d-glucals 16–18 bearing pivalo-
yl,
tert-butyldimethylsilyl
(TBS), and benzyl protective
groups, respectively (Scheme 4).
The results are summarized in
Table 1. When the per-pivaloat-
ed d-glucal 16 was engaged in Scheme 5. Rationalization of the b-gluco stereoselectivity of the fluorophosphorylation.
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S. P. Vincent et al.
Table 2. Structural characteristics of the contacts between the fluorine
atom of 2 and heptosyltransferase WaaC.
stitution by the phosphate, implying an inversion of the
anomeric configuration.
Distances
[Š]Angles
[
8]
Given the high b-selectivity of this new procedure, we
were confident that we could efficiently complete the syn-
thesis of our target molecule 2. After optimization of the re-
action temperatures with starting heptosylglycals 12 and 13
(entries 10 and 11), we obtained results that nicely corrobo-
rate the glucal series. The pivaloylated and the silylated gly-
cals gave an excellent b-gluco selectivity. The yields are
moderate, but consistent with the literature data for this
F···N (His 266)
F···O (Thr262)
F···C=O (Thr262)
F···Ca-C=O (Thr262)
3.25
3.40
2.95
3.23
C-F···CWaaC
F···C=O
122.5
100.6
126.4
torsional angle
C-F···C=O
F···H-Ca-C=O (Thr262)
2.67
A
surprised by the short distance between the F atom and the
carbonyl group of the peptidic backbone, which is signifi-
cantly lower than the sum of the van der Waals radii of C
and F atoms.
Completion ofthe synthesis of2 : Although the most reason-
able deprotection sequence consists of deprotecting the car-
bohydrate first and then the phosphate by hydrogenoly-
On the one hand, the implication of hydrogen bonds be-
tween organofluorines and proteins has been the subject of
controversies.[26] In this structure, a hydrogen bond with the
C-H of Thr262 cannot be reasonably invoked. On the other
hand, unexpected attractive interactions between organo-
fluorines and the carbon atom of carbonyl groups have been
clearly evidenced in the recent literature.[27–29] This type of
interaction was discovered by Diederich, Müller, and collab-
orators after analyzing the X-ray crystal structure of throm-
bin in complex with a fluorinated inhibitor, followed by a
database mining of the Cambridge Structural Database.
Moreover, their attractive character has been shown by
NMR spectroscopy and measurement of free enthalpies.[28,30]
As illustrated in Table 2, the contact observed between
ADP-2-fluoro-heptose 2 and WaaC nicely corresponds to
what has been evidenced as orthogonal multipolar interac-
tions:[27] a short F···C=O distance, an orthogonal position of
the fluorine atom above the pseudotrigonal axis of the car-
sis,[7,24]
a
reverse sequence gave far better results
(Scheme 6). After screening various nucleophiles (MeLi,
Scheme 6. Reagents and conditions: a) H2, Pd/C; TBAOH, H2O, RT,
quant; b) H2, Pd/C; TBAF, THF, 55% for 2 steps; c) AMP-morpholidate,
1H-tetrazole, Py, RT (56%).
LiAlH4, diisobutylaluminum hydride (DIBAL), NaOH) for
the deprotection of the four pivaloates of 14, tetrabutyl-
ꢀ
A
bonyl group and a C F/C=O torsional angle between 100
and 1408.
could achieve cleanly this deprotection. Surprisingly, the tet-
rabutyl ammonium fluoride (TBAF) deprotection of 15b
was troublesome, especially if performed before the hydro-
genolysis. After optimization of the conditions, we could
obtain the fully deprotected fluorophosphate 25 in pure
form in quantitative and 55% yields from 14 and 15b, re-
spectively. Target molecule 2 was obtained in 56% yield by
using the tetrazole-catalyzed morpholidate coupling proce-
dure.[25]
Given these geometrical data, this C-F···C=O interaction
is not fortuitous and contributes to the binding of inhibitor 2
into the catalytic pocket of WaaC. At this stage, it is difficult
to discuss whether this interaction slightly modifies the posi-
tioning of the heptose moiety compared to the natural sub-
strate 1, since all attempts to cocrystallize 1 and WaaC
failed.[12]
Analysis ofthe contacts between the lfuorine atom and the
protein: It should be noted that final molecule 2 is a gluco-
heptoside, whereas the natural substrate of bacterial hepto-
syltransferase WaaC, molecule 1, is a manno-heptoside.
Nevertheless, due to the electron-withdrawing character of
the fluorine atom, ADP-2F-heptose 2 displayed competitive
inhibition against WaaC with an IC50 of 30 mmol.[12] Gratify-
ingly, the structure of WaaC in complex with 2 was obtained
and allowed the analysis of the interactions between the
transferase and its substrate. To our surprise, the equatorial
fluorine of the pyranose contacts the side chain of His266
and the amide group of Gly263/Thr262 peptidic bond. The
Conclusion
In a general perspective, this work contributes to the grow-
ing field of the synthesis of biologically relevant fluorinated
molecules. A survey of the recent literature data highlights
1) the need for developing new efficient and stereoselective
fluorination methodologies,[31] and 2) the very broad range
of applications exploiting fluorinated molecules, going from
drug design[29,32] to supramolecular chemistry. Fluorinated
carbohydrates themselves have found many applications
from mechanistic enzymology[7,10,33] to positron emission to-
mography (PET).[34] The work detailed in this study required
both the development of a b-stereoselective fluorophosphor-
ylation methodology and the synthesis of a challenging
ꢀ
lengths and angles of the C F bond and the neighboring
protein residues are summarized in Table 2. We were first
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Stereoselective Glycal Fluorophosphorylation
FULL PAPER
tracted with dichloromethane. The combined organic layers were washed
with 1n aq. HCl, satd aq. NaHCO3, and brine, dried over MgSO4, fil-
tered, and concentrated in vacuo. The residue was subjected to chroma-
tography on a silica gel column (cyclohexane/ethyl acetate=5:1) to
afford a mixture of diacetates 6d and 6l (ratio 3:7) as a colorless syrup
(1,26 g, 84%).
NDP-sugar analogue of an important intermediate of the
LPS biosynthesis. To the best of our knowledge, this mole-
cule is the best inhibitor of heptosyl transferase reported to
date[35] and its co-crystallization with the target bacterial
enzyme will allow us to rationally design a new generation
of inhibitors of the LPS biosynthetic pathway.
Data for 6d: 1H NMR (400 MHz, CDCl3, 258C): d=7.40 (m, 15H;
ArH), 5.51 (ddd, J5,6 =2.2 J6,7a =3.1 J6,7b =8.4 Hz, 1H; H-6), 4.68–5.08 (m,
6H; ArCH2), 4.59 (d, J1,2 =3.6 Hz, 1H; H-1), 4.28 (dd, J6,7a =3.1 J7a,7b
12.1 Hz, 1H; H-7a), 4.15 (dd, J6,7b =8.4 J7a,7b =12.1 Hz, 1H; H-7b),4.03 (t,
2,3 =J3,4 =9.4 Hz, 1H; H-3), 3.86 (dd, J5,6 =2.2 J4,5 =10.3 Hz, 1H; H-5),
3.53 (t, J3,4 9.4 Hz, J4,5 9.8 Hz, 1H; H-4), 3.51 (dd, J1,2 =3.6 Hz, J2,3
=
J
Experimental Section
=
9.4 Hz, 1H; H-2), 3.42 (s, 3H; OMe), 2.08 (s, 3H; Ac), 2.05 ppm (s, 3H;
Ac); 13C NMR (101 MHz, CDCl3, 258C): d=170.6, 169.9, 138.5, 138.0,
137.8, 128.4, 128.3, 128.2, 128.0”2, 127.9, 127.7, 127.6, 97.7, 82.1, 79.7,
General techniques: All reactions were carried out under an argon
ACHTREUNG
ACHTREUNG
77.7, 75.8, 74.7, 73.4, 70.5, 70.3, 62.5, 55.1, 20.9, 20.8 ppm; MSCAHTRE(UNG DCI): m/z:
freshly dried over sodium benzophenone, dichloromethane over P2O5,
and acetonitrile and nitromethane over CaH2. Reagents were purchased
at the highest commercial quality from Sigma-Aldrich or Acros, and used
without further purification. All reactions were monitored by thin-layer
chromatography (TLC) carried out on Merck aluminum roll silica gel 60-
F254 using UV light and ethanoic phosphomolybdic acid or ethanoic sulfu-
596 [M+NH4]+.
1
Data for 6l: H NMR (400 MHz, CDCl3, 258C): d=7.40 (m, 15H; ArH),
5.51 (ddd, J5,6 =2.0 HzJ6,7a =7.3 J6,7b =6.3 Hz, 1H; H-6), 4.68–5.08 (m,
6H; ArCH2), 4.70 (d, J1,2 =3.0 Hz, 1H; H-1), 4.31 (dd, J6,7a =7.3 J7a,7b
11.1 Hz, 1H; H-7a), 4.26 (dd, J6,7b =6.3 J7a,7b =11.1 Hz, 1H; H-7b), 4.08 (t,
2,3 =J3,4 =9.7 Hz, 1H; H-3), 3.90 (dd, J4,5 =10.3 HzJ5,6 =2.0 Hz, 1H; H-5),
3.59 (dd, J1,2 =3.4 Hz, J2,3 =9.7 Hz, 1H; H-2), 3.46 (dd, J3,4 =10.0 HzJ4,5
=
1
ric acid for visualization. H, 13C, 19F, and 31P NMR spectra were recorded
J
with a Bruker AC-250 and AMX-400 spectrometer. All compounds were
characterized by 1H, 13C, 19F, and 31P NMR as well as by 1H–1H correla-
tion experiment. The following abbreviations were used to describe the
multiplicities: s=singlet, d=doublet, t=triplet, m=multiplet, br=broad,
brs=broad singlet. Merck silica gel (60, particle size 0.040–0.063 mm)
was employed for flash column chromatography using cyclohexane-ethyl
acetate as eluting solvents. Size-exclusion chromatography was per-
formed with a Pharmacia Biotech ¾kta FPLC apparatus on Sephadex
G15 column (2.5”60 cm), and the fractions containing adenine deriva-
tives were detected by UV light. Purifications of nucleotide sugars were
realized by semipreparative HPLC using a Waters Delta prep 4000 chro-
matography system equipped with a NovaPack C18 column (eluent: tri-
=
10.3 Hz, 1H; H-4), 3.39 (s, 3H; OMe), 2.16 (s, 3H; Ac), 2.08 ppm (s, 3H;
Ac); 13C NMR (101 MHz, CDCl3, 258C): d=170.4, 170.0, 138.3, 137.8,
137.5, 128.5, 128.48, 128.41, 128.37, 128.1, 128.0, 127.9, 127.8, 98.1, 82.1,
79.5, 76.7, 75.9, 75.3, 73.4, 68.4, 68.0, 62.1, 55.3, 20.9, 20.7 ppm; MSACHTREUNG(DCI):
m/z: 596 [M+NH4]+.
Methyl 6,7-anhydro-2,3,4-tri-O-benzyl-d/l-glycero-d-gluco-heptopyrano-
side (7): mCPBA (7.53 g, 30.6 mmol) was added to a solution of olefin 4
(4.69 g, 10.2 mmol) in dichloromethane (10 mL) at 08C. The reaction
mixture was then stirred for 12 h at room temperature. After addition of
potassium carbonate, the solution was poured into water and extracted
by dichloromethane three times. The combined organic layers were
washed with saturated aqueous solution of NaHCO3 and brine, dried
over MgSO4, and concentrated in vacuo. The residue was purified by
silica gel chromatography (cyclohexane/ethyl acetate 3:1 then 1:1) to give
epoxide 7 (7:3 diastereomeric mixture) as a colorless syrup (4.21 g,
8.8 mmol, 87%). 1H NMR (400 MHz, CDCl3, 258C): d=7.60–7.35 (m,
15H; ArH), 4.68–5.04 (m, ArCH2L,D), 4.61 (d, J1,2 =3.6 Hz, 0.7H; H-1L),
4.58 (d, J1,2 =3.6 Hz, 0.3H; H-1D), 4.01–4.07 (m, H-3L,D), 3.72 (dd, J=4.0,
ACHTREUNGethylammonium acetate 50 mm, pH 6.8).
Methyl 2,3,4-tri-O-benzyl-d/l-glycero-a-d-gluco-heptopyranoside (5):
OsO4 (2.5% in tBuOH, 1.82 mL) was added to a solution of olefin 4[36]
(2.18 g, 4.72 mmol) and NMO (1.27 g, 9.44 mmol) in acetone (25 mL)
and water (3 mL). After 13 h at room temperature, the reaction mixture
was poured into aq. Na2S2O3 (5%, 20 mL) and stirred for 30 min. The
aqueous phase was extracted three times with dichloromethane. The
combined organic layers were washed with a saturated aqueous solution
of NaHCO3 then brine, dried over MgSO4, and concentrated in vacuo.
The residue was purified by silica gel chromatography (cyclohexane/ethyl
acetate 3:1) to give diol 5 as a colorless syrup (2.15 g, 92%, diastereo-
meric mixture d/l=9:1). This molecule has been previously described in
the literature.[16]
9.9 Hz, 0.3H; H-5D), 3.45–3.58 (m, H-2L,D, H-4L, H-5L), 3.47 (dd, J4,5
8.9 Hz J4,3 =9.6 Hz, 0.3H; H-4D), 3.40 (s, 3H; OMeL), 3.39 (s, 3H;
OMeD), 3.16 (m, H-6L,D), 2.81 and 2.87 (ABX, 6,7a =2.8 Hz, J6,7b
4.3 HzHz, J7a,7b =5.4 Hz, 1.4H; H-7L), 2.67–2.75 ppm (ABX, J6,7a =2.7 Hz,
6,7b =4.0 HzJ7a,7b =5.4 Hz, 0.3H; H-7D); 13C NMR (101 MHz, CDCl3,
=
J
=
J
258C): d=138.7, 138.1, 138.0, 137.8, 133.4, 130.1, 130.0, 128.4, 128.3,
128.2, 128.0, 127.9, 127.7, 127.6, 98.1 (l), 97.8 (d), 81.9 (l), 81.8 (d), 80.3
(d), 79.9 (d), 79.7 (l), 79.5 (l), 75.9 (l), 75.5 (d), 75.0 (d), 73.5 (l), 70.3
(l), 68.7 (d), 55.5 (l), 55.3 (d), 52.1 (d), 51.6 (l), 44.5 (l), 43.9 ppm (d);
MS (DCI-NH3): m/z: 494 [M+NH4]+; HRMS calcd for C29H36O6N
[M+NH4]+: 494.2543; found: 494.2549.
Methyl 6,7-di-O-acetyl-2,3,4-tri-O-benzyl-d-glycero-a-d-gluco-heptopyra-
noside (6d) and methyl 6,7-di-O-acetyl-2,3,4-tri-O-benzyl-l-glycero-a-d-
gluco-heptopyranoside (6l)
Peracetylation procedure: Acetic anhydride (3 equiv) and
a catalytic
amount of DMAP was added to a solution of diol 5 (950 mg, 1.92 mmol)
in anhydrous pyridine (9.0 mL). After stirring overnight at room temper-
ature, the reaction mixture was poured into ice water and extracted with
dichloromethane. The combined organic layers were washed with 1n aq.
HCl, satd aq. NaHCO3, and brine, dried over MgSO4, filtered, and con-
centrated in vacuo. The residue was subjected to chromatography on a
silica gel column (cyclohexane/ethyl acetate=5:1) to afforded a mixture
of diacetates 6d and 6l (ratio 9:1) as a colorless syrup (quantitative).
Methyl 6-O-acetyl-2,3,4-tri-O-benzyl-7-O-tert-butyldimethylsilyl-l-glyc-
ero-a-d-gluco-heptopyranoside (9l): TBDMSCl (94 mg, 0.607 mmol) was
gradually added to a solution of diol 5 (200 mg, 0.404 mmol), DMAP
(4.9 mg, 0.040 mmol), and triethylamine (165 mL, 1.21 mmol) in pyridine
(35 mL) at 08C. After stirring 13 h at room temperature, the reaction
mixture was poured into saturated aqueous solution of NaHCO3 and the
aqueous phase was extracted by dichloromethane. The combined organic
layers were washed with saturated aqueous solution of NaHCO3 then
brine, dried over MgSO4, and concentrated in vacuo. The residue was pu-
rified by silica gel chromatography (cyclohexane/ethyl acetate 5:1) to fur-
nish intermediate silyl ether 8[37] as a colorless syrup (224 mg, 91%). Tri-
fluoromethanesulfonic anhydride (188 mL, 1.15 mmol) was added drop-
wise to a solution of silyl ether 8 (234 mg, 0.384 mmol) in pyridine
(10 mL) at ꢀ408C, then the reaction mixture was allowed to warm to
08C and stirred for 1 h. After concentration in vacuo, the residue was
subjected to chromatography on silica gel (cyclohexane/ethyl acetate
From methyl 6,7-anhydro-2,3,4-tri-O-benzyl-d/l-glycero-d-gluco-hepto-
pyranoside (7): A solution of epoxide 7 (1.24 g, 2.60 mmol), cesium ace-
tate (2.49 g, 13.0 mmol), and [18]crown-6 (3.44 g, 13.0 mmol) in DMF
(20 mL) was stirred vigorously at 1008C for 3 h. The reaction mixture
was poured into brine, and the organic layer was extracted with ethyl
acetate. The organic layer was dried over MgSO4, filtered, and concen-
trated in vacuo. The residue was dissolved into pyridine (15 mL), and the
mixture was added acetic anhydride (10 mL). After stirring at room tem-
perature for 13 h, the reaction mixture was poured into ice water and ex-
Chem. Eur. J. 2008, 14, 9530 – 9539
ꢁ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
9535

S. P. Vincent et al.
5:1), and all the fractions were successively concentrated and dried in
vacuo. The resulting triflate was dissolved into anhydrous toluene
(10 mL), and cesium acetate (223 mg, 1.16 mmol) and 18-crown-6
(305 mg, 1.16 mmol) were added. The reaction mixture was sonicated for
6 h at room temperature, and diluted into ethyl acetate. The organic
layer was washed with brine, dried over MgSO4, and concentrated in
vacuo. The residue was purified by silica gel chromatography (cyclohex-
ane/ethyl acetate 8:1) to give acetate 9l as a colorless syrup (160 mg,
2 h. The solution was concentrated in vacuo, and the residue was dis-
solved in pyridine (20 mL). Pivaloyl chloride (2.10 mL, 17.0 mmol) was
added dropwise to this solution at 08C, and the mixture was allowed to
warm to room temperature. After 12 h at room temperature under
argon, cold saturated aq. NaHCO3 was added, and the mixture was ex-
tracted twice with dichloromethane. The combined organic layers were
washed with brine, dried over MgSO4, and concentrated in vacuo. The
residue was purified by silica gel chromatography (hexane/ethyl acetate
10:1) to afford pivaloate 12 as a white powder (598 mg, 82%): [a]2D3
=
1
64%): [a]D23 =ꢀ4.0 (c=0.5 in CHCl3); H NMR (400 MHz, CDCl3, 258C):
ꢀ17.6 (c=0.5 in CHCl3); 1H NMR (400 MHz, CDCl3, 258C): d=6.46 (d,
d=7.40 (m, 15H; ArH), 5.43 (t, J5,6 =J6,7 =7.1 Hz, 1H; H-6), 4.71–5.09
(m, 5H; ArCH2), 4.74 (d, J1,2 =3.6 Hz, 1H; H-1), 4.54 (d, J=10 Hz, 1H;
CH2-Ar), 4.11 (t, J2,3 =J3,4 =9.2 Hz, 1H; H-3), 4.04 (brd, J4,5 =10.1 Hz,
1H; H-5), 3.80 (m, 2H; H-7), 3.62 (dd, J1,2 =3.5 Hz, J2,3 =9.7 Hz, 1H; H-
2), 3.49 (dd, J3,4 =9.6 Hz, J4,5 =10 Hz, 1H; H-4), 3.46 (s, 3H; OMe), 2.15
(s, 3H; Ac), 0.94 (s, 9H; SitBu), 0.11 and 0.13 ppm (s”2, 6H; SiMe);
13C NMR (101 MHz, CDCl3, 258C): d=170.0, 138.5, 138.0, 137.8, 128.4,
128.3, 128.2, 128.0”2, 127.9, 127.7, 127.6, 97.9, 82.3, 79.6, 76.9, 75.8, 75.1,
J
J
1,2 =6.0 Hz, J1,3 =1.4 Hz, 1H; H-1), 5.44 (ddd, J1,3 =1.6 Hz, J2,3 =2.3 Hz,
3,4 =7.0 Hz, 1H; H-3), 5.40 (ddd, J5,6 =2.9 Hz, J6,7 =4.3, 7.4 Hz, 1H; H-
6), 5.28 (dd, J3,4 =7.0 Hz, J4,5 =9.5 Hz, 1H; H-4), 4.79 (dd, J1,2 =6.0 Hz,
2,3 =2.5 Hz, 1H; H-2), 4.38 (dd, J6,7 =4.4 Hz, Jgem =11.7 Hz, 1H; H-7),
4.23 (dd, J4,5 =9.6 Hz, J5,6 =2.9 Hz, 1H;H-5), 4.20 (dd, J6,7 =7.4 Hz, Jgem
J
=
11.6 Hz, 1H; H-7), 1.26, 1.20, 1.19 and 1.18 ppm (4s, 36H; tBu);
13C NMR (101 MHz, CDCl3, 258C): d=178.0, 177.9, 177.0, 176.2, 145.5,
99.9, 75.2, 69.2, 66.2, 65.5, 62.9, 38.7”2, 27.1, 27.0”2, 26.9 ppm; MS-
73.1, 70.7, 67.2, 60.0, 55.1, 25.7, 20.9, 18.0, ꢀ5.4, ꢀ5.6 ppm; MS
ACHTRE(UNG DCI):
AHCTREUNG
(DCI): m/z: 530 [M+NH4]+; HRMS calcd for C27H48O9N [M+NH4]+:
m/z: 668 [M+NH4]+; HRMS calcd for C37H54O8NSi [M+NH4]+:
530.3329; found: 530.3336; elemental analysis calcd (%) for C27H44O9: C
63.26, H 8.65; found: C 63.13, H 8.81.
668.3619; found: 668.3628.
1,2,3,4,6,7-Hexa-O-acetyl-l-glycero-d-gluco-heptopyranose (10): Conc.
H2SO4 (2.93 mL) was added dropwise to a solution of silyl ether 9l
(3.91 g, 5.99 mmol) and acetic anhydride (7.53 mL) in chloroform
(4.89 mL) at 08C. The reaction mixture was allowed to warm to room
temperature and stirred for 12 h. After addition of potassium carbonate,
the solution was poured into water and extracted by dichloromethane
three times. The combined organic layers were washed with saturated
aqueous solution of NaHCO3 then brine, dried over MgSO4, and concen-
trated in vacuo. The residue was purified by silica gel chromatography
(cyclohexane/ethyl acetate 3:1 then 1:1) to give acetate 10 as a colorless
syrup (2.27 g, 82%, a/b=88:12): 1H NMR (400 MHz, CDCl3, 258C): d=
6.34 (d, J1,2 =3.8 Hz, 1 H; H-1a), 5.66 (d, J1,2 =8.3 Hz, 0.14 H; H-1b), 5.46
1,5-Anhydro-2-deoxy-3,4,6,7-tetra-O-tert-butyldimethylsilyl-l-galacto-
hept-1-enitol (13): Sodium (10 mg) was added to a suspension of acetate
11 (894 mg, 2.6 mmol) in MeOH (5 mL), and the reaction mixture was
stirred for 2 h. The solution was concentrated in vacuo, and the residue
was dissolved in anhydrous N,N-dimethylformamide (20 mL). imidazole
(2.83 g, 41.6 mmol) then TBDMSCl (4.70 g, 31.1 mmol) was added to this
suspension at 08C. After stirring 12 h at room temperature, the solution
was poured into brine and the aqueous phase was extracted by ethyl ace-
tate three times. The combined organic layers were washed with saturat-
ed aqueous solution of NaHCO3 then brine, dried over MgSO4, and con-
centrated in vacuo. Purification of the residue by silica gel chromatogra-
phy (cyclohexane/ethyl acetate 3:1 then 1:1) gave glycal 13 as a white
powder (1.56 g, 2,47 mmol, 95%). [a]D23 =ꢀ21.1 (c=0.5 in CHCl3);
1H NMR (400 MHz, CDCl3, 258C): d=6.37 (d, J1,2 =6.4 Hz, 1H; H-1),
4.75 (ddd, J1,2 =6.4 Hz, J=1.6, 5.0 Hz, 1H; H-2), 4.22 (m, 2H; H-5 and
(d,
J2,3 =J3,4 =10.0 Hz, 1 H; H-3a), 5.25 (ddd, J5,6 =2.1 Hz, J6,7 =5.2,
7.2 Hz, 1 H; H-6a), 5.12 (dd, J1,2 =3.6 Hz, J2,3 =9.1 Hz, 1 H; H-2a), 5.10
(t, J3,4 =J4,5 =9.8 Hz, 1 H; H-4a), 4.27 (dd, J6,7 =5.0 Hz, Jgem =11.7 Hz,
1 H; H-7a), 4.19 (dd, J4,5 =10.2 Hz, J5,6 =2.1 Hz, 1 H; H-5a), 4.15 (dd,
H-6), 4.03 (dd, J=1.8, 4.0 Hz, 1H; H-4), 3.71 and 3.96 (2dd, J6,7b
=
J
6,7 =7.6 Hz, Jgem =11.7 Hz, 1 H; H-7a), 2.02–2.19 ppm (m, 20 H;
2.0 Hz, J6,7a =2.1 Hz, Jgem =8.6 Hz, 2H; H-7), 3.87 (m, 1H; H-3), 0.94 (s,
18H; SitBu), 0.91 (s, 9H; SitBu), 0.90 (s, 9H; SitBu), 0.06–0.14 ppm (7s,
24H; SiMe); 13C NMR (101 MHz, CDCl3, 258C): d=143.4, 100.5, 79.4,
69.4, 69.3, 66.4, 65.9, 26.9, 26.2, 26.0, 25.8, 25.78, 18.6, 18.2, 18.0, 17.9,
COCH3); 13C NMR (101 MHz, CDCl3, 258C): d=170.4, 170.2, 170.1,
169.6, 169.3, 168.5, 92.0 (C-1b), 88.7 (C-1a), 70.0, 69.9, 69.0, 66.9, 66.5,
(DCI): m/z: 480 [M+NH4]+;
62.1, 20.7, 20.6”3, 20.4, 20.3 ppm; MSACHTREUNG
HRMS calcd for C19H30O13N [M+NH4]+: 480.1717; found: 480.1711.
ꢀ4.3, ꢀ4.4”3, ꢀ4.6”2, ꢀ5.1, ꢀ5.5 ppm; MS
(DCI): m/z: 650 [M+NH4]+;
ACHTREUNG
HRMS calcd for C31H68O5Si4Na [M+Na]+: 655.4041; found: 655.4057; el-
emental analysis calcd (%) for C31H68O5Si4: C 58.80, H 10.82; found: C
58.77, H 10.97.
1,5-Anhydro-2-deoxy-3,4,6,7-tetra-O-acetyl-l-galacto-hept-1-enitol (11):
HBr-AcOH (9.68 mL, 56.3 mmol) was added to a solution of heptose 10
(2.17 g, 4.69 mmol), acetic anhydride (1.32 mL), and acetic acid
(1.12 mL) in dichloromethane (4 mL), and the reaction mixture was
stirred for 12 h at room temperature. The reaction was quenched by addi-
tion of sodium acetate (4.61 g, 56.3 mmol). The suspension was trans-
ferred into a suspension of CuSO4 (186 mg, 1.17 mmol), zinc powder
(11.7 g, 178 mmol), and sodium acetate (8.78 g, 113 mmol) in water
(9.2 mL) and acetic acid (13.8 mL). The mixture was vigorously stirred
for 4 h at room temperature then filtered through a pad of Celite, which
was washed with ethyl acetate and water. The organic layer of the filtrate
was washed with saturated aqueous solution of NaHCO3 then brine,
dried over MgSO4, and concentrated in vacuo. The residue was purified
by silica gel chromatography (cyclohexane/ethyl acetate 3:1) to furnish
glycal 11 as a colorless syrup (1.47 g, 91%): [a]D23 =ꢀ13.8 (c=0.5 in
CHCl3); 1H NMR (400 MHz, CDCl3, 258C): d=6.44 (dd, J1,2 =6.2 Hz,
2-Deoxy-1-O-dibenzylphosphoryl-2-fluoro-3,4,6,7-tetra-O-pivaloyl-l-glyc-
ero-b-d-gluco-heptopyranose (14): A mixture of pivaloate 12 (543 mg,
1.06 mmol) and MS 4 Š (200 mg) in anhydrous nitromethane (15 mL)
was stirred for 2 h at room temperature under argon atmosphere. Select-
fluor-(TfO)2 (761 mg, 1.59 mmol) was added very quickly at 08C, and the
reaction mixture was allowed to warm to room temperature. After 12 h
of stirring, sodium dibenzylphosphate (955 mg, 3.18 mmol) and
[15]crown-5 (700 mg, 3.18 mmol) was added with flowing argon gas, and
the mixture was heated to 608C and stirred for 16 h. The suspension was
filtered through a pad of Celite, and the pad was washed with dichloro-
methane. The filtrate was concentrated in vacuo, and the residue was
subjected to chromatography on silica gel (hexane/ethyl acetate 5:1) to
give fluorophosphate 14 (497 mg, 58%) as a colorless syrup. [a]D23 =ꢀ1.7
(c=0.5 in CHCl3); 1H NMR (400 MHz, CDCl3, 258C): d=7.38 (m, 10H;
J
1,3 =1.6 Hz, 1H; H-1), 5.48 (ddd, J1,3 =1.8 Hz, J2,3 =2.4 Hz, J3,4 =7.2 Hz,
1H; H-3), 5.38 (m, 1H; H-6), 5.25 (dd, J3,4 =7.3 Hz, J4,5 =9.9 Hz, 1H; H-
4), 4.79 (dd, J1,2 =6.2 Hz, J2,3 =2.4 Hz, 1H; H-2), 4.35 (dd, J6,7 =4.8 Hz,
ArH), 5.43 (ddd, J1,2 =7.7 Hz, J1,F =2.8 Hz, 1H; H-1), 5.38 (dt, J2,3 =J3,4
=
9.3 Hz, J3,F =13.3 Hz, 1H; H-3), 5.26 (ddd, J5,6 =1.9 Hz, J6,7 =4.6, 8.0 Hz,
1H; H-6), 5.06–5.18 (m, 4H; ArCH2), 5.11 (t, J3,4 =J4,5 =9.8 Hz, 1H; H-
4), 4.45 (ddd, J1,2 =7.8 Hz, J2,3 =9.0 Hz, J2,F =50.6 Hz, 1 H; H-2), 4.28 (dd,
J
gem =11.7 Hz, 1H; H-7a), 4.19 (m, 2H; H-5, H-7b), 2.03–2.09 ppm (4s,
12H; COCH3); 13C NMR (101 MHz, CDCl3, 258C): d=170.6, 170.4,
170.2, 169.6, 145.5, 100.0, 74.6, 69.4, 66.6, 66.1, 62.3, 20.9, 20.6 ppm; MS-
J
6,7 =4.7 Hz, Jgem =11.7 Hz, 1H; H-7), 4.04 (dd, J6,7 =8.1 Hz, Jgem =
ACHTREUNG
(DCI): m/z: 362 [M+NH4]+; elemental analysis calcd (%) for C15H20O9:
11.6 Hz, 2 H; H-7), 3.91 (dd, J4.5 =10.1 Hz, J5,6 =2.0 Hz, 1H; H-5), 1.18–
1.25 ppm (4s, 12H; tBu); 13C NMR (101 MHz, CDCl3, 258C): d=177.7,
177.0, 176.7, 176.0, 135.2 (d), 135.1 (d), 128.6”2, 128.0, 127.9, 96.2 (dd,
C 52.32, H 5.85; found: C 52.32, H 5.84.
1,5-Anhydro-2-deoxy-3,4,6,7-tetra-O-pivaloyl-l-galacto-hept-1-enitol
(12): Sodium (10 mg) was added to a suspension of acetate 11 (488 mg,
1.42 mmol) in MeOH (5 mL), and the reaction mixture was stirred for
J
1,F =4.9 Hz, J1,P =24.3 Hz), 89.6 (dd, J2,F =193 Hz, J1,P =9.0 Hz), 73.6,
72.0 (d, J3,F =19 Hz)„ 69.7? (d), 69.6(d), 65.8, 65.6 (d, J4,F =7 Hz), 62.7,
9536
www.chemeurj.org
ꢁ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2008, 14, 9530 – 9539

Stereoselective Glycal Fluorophosphorylation
FULL PAPER
38.8, 38.74, 38.65, 38.6, 30.1, 27.1, 26.95, 26.92, 26.85 ppm; 19F NMR
19.4 Hz, C-3), 69.62 (d, J=5.7 Hz, CH2Ph), 69.54 (d, J=5.5 Hz, CH2Ph),
(235 MHz, D2O, 25 8C): d=ꢀ199.2 ppm (dd, J2,F =51.7 Hz, J3,F =14.1 Hz);
66.6 (d, JF,4 =7.4 Hz, C-4), 61.17 (C-6), 38.80, 38.76 (C
26.98 ppm (C
ACHTRE(UGN CH3)3), 27.02,
31P NMR (101 MHz, D2O, 25 8C): d=ꢀ2.93 ppm (s); MS
(DCI): m/z: 826
G
[M+NH4]+; HRMS calcd for C41H59O13FP [M+H]+: 809.3677; found:
809.3682.
(d, JP, 1 =7.6 Hz); 19F NMR (235 MHz, CDCl3, 258C); d=ꢀ201.20 ppm
(ddd, JF,2 =50.8 Hz, JF,3 =13.7 Hz, JF,1 =3.0 Hz); MS-CI: m/z (%): 712
(100) [M+NH4]+; elemental analysis calcd (%) for C35H48FO11P (%): C
60.51, H 6.96; found: C 60.37, H 7.14.
2-Deoxy-1-O-dibenzylphosphoryl-2-fluoro-3,4,6,7-tetra-O-tert-butyldime-
thylsilyl-l-glycero-b-d-gluco-heptopyranose (15b) and 2-deoxy-1-O-di-
benzylphosphoryl-2-fluoro-3,4,6,7-tetra-O-tert-butyldimethylsilyl-l-glyc-
ero-a-d-gluco-heptopyranose (15a): The procedure described for the
preparation of 14 was applied to glycal 13 (342 mg, 0.540 mmol). The
final residue was subjected to chromatography on silica gel (toluene then
cyclohexane/ethyl acetate 10:1) to give fluorophosphates 15b (256 mg,
51%) and 15a (15 mg, 3%) as colorless syrups.
Data for 19c: White solid, m.p. 788C; [a]D20 =+788 (c=0.8 in CHCl3);
1H NMR (400 MHz, CDCl3, 258C): d=7.42–7.30 (m, 10H; C6H5), 5.76
(td, J1,2 =1.9 Hz, J1,P =J1,F =5.2 Hz, 1H; H-1), 5.50 (dd, J3,4 =10.1 Hz,
J4,5 =10.1 Hz, 1 H; H-4), 5.16 (ddd, J3,4 =10.3 Hz, J3,F =28.5 Hz, J2,3
2.5 Hz, 1H; H-3), 5.15–5.08 (m, 4H; OCH2Ph), 4.54 (ddd, J2,3 =J1,2
=
=
2.2 Hz, J2,F =49.0 Hz, 1H; H-2), 4.08–3.96 (m, 3H; H5, H-6), 1.23 (s, 9H;
CH3), 1.22 (s, 9H; CH3), 1.18 ppm (s, 9H; CH3); 13C NMR (100 MHz,
CDCl3, 258C): d=177.9, 177.4, 176.1 (CO), 135.2, 135.17 (Cipso), 128.84–
127.94 (m, C6H5), 94.50 (dd, JP, 1 =31.7 Hz, JF,1 =5.4 Hz, C-1), 86.00 (dd,
Data for 15b: [a]D23 =+2.6 (c=0.5 in CHCl3); 1H NMR (400 MHz,
CDCl3, 258C): d=7.37 (m, 10H; ArH), 5.41 (td, J1,2 =J1,P =7.7 Hz, J1,F
3.2 Hz, 1H; H-1), 5.01–5.17 (m, 4H; ArCH2), 4.21 (td, J1,2 =J2,3 =7.7 Hz,
2,F =50.7 Hz, 1H; H-2), 4.06 (ddd, J5,6 =1.6 Hz, J6,7 =5.5, 7.4 Hz, 1H; H-
6), 3.95 (td, J2,3 =7.7 Hz, J3,4 =8.0 Hz, J3,F =16.0 Hz, 1H; H-3), 3.89 (t,
3,4 =J4,5 =8.0 Hz, 1H; H-4), 3.72 (dd, J6,7 =7.7 Hz, Jgem =9.7 Hz, 1H; H-
=
J
F,2 =180.4 Hz, JP, 2 =9.0 Hz, C-2), 70.60 (C-5), 70.1, (d, J=5.5 Hz,
J
CH2Ph), 69.9 (d, J=5.6 Hz, CH2Ph), 68.8 (d, JF,3 =16.5 Hz, C-3), 63.77
(C-4), 60.74 (C-6), 38.8, 38.7, 27.0, 26.9 ppm; 31P NMR (101 MHz, CDCl3,
J
258C): d=ꢀ2.99 ppm (d,
J
P, 1 =5.2 Hz); 19F NMR (235 MHz, CDCl3,
258C); d=ꢀ204.90 ppm (ddd, JF,2 =49.0 Hz, JF,3 =28.5 Hz, JF,1 =4.3 Hz);
MS-CI: m/z (%): 712 (100) [M+NH4]+; elemental analysis calcd (%) for
C35H48FO11P: C 60.51, H 6.96; found: C 60.41, H 7.11.
7), 3.59 (m, 2H; H-5, H-7), 0.96 (s, 9H; SitBu), 0.92 (s, 9H; SitBu), 0.91
(s, 9H; SitBu), 0.90 (s, 9H; SitBu), 0.04–0.19 ppm (7s, 24H; SiMe);
13C NMR (101 MHz, CDCl3): d=135.6, 135.5, 128.5, 128.4”2, 127.9,
127.8, 96.4? (dd, J1,F =4.8 Hz, J1,P =26.2 Hz), 92.5 (dd, J2,F =189 Hz, J1,P
=
8 Hz), 77.1 (d, J3,F =17 Hz), 76.7, 72.0 (d, J4,F =7 Hz), 71.3, 69.4 (d),
69.3(d), 26.2, 26.0, 25.91, 25.89, 18.6, 18.3, 18.27, 18.1, ꢀ2.5, ꢀ3.2, ꢀ3.3,
ꢀ3.35, ꢀ3.4, ꢀ3.5, ꢀ3.7, ꢀ4.0 ppm; 19F NMR (235 MHz, CDCl3, 258C):
Dibenzyl(2-deoxy-2-fluoro-3,4,6-tri-O-tert-butyldimethylsilyl-b-d-gluco-
pyranosyl)phosphate (20b): Compound 17[38] (600 mg, 1.23 mmol) was
solubilized in nitromethane (24 mL) and stirred with 4 Š molecular
sieves (1 g) under argon for 15 min. Selectfluor (500 mg, 1.04 mmol) was
added at 08C and the reaction mixture was stirred for 4 h at ambient
temperature. [15]Crown-5 (736 mL, 3.68 mmol) and dibenzylphosphate
(sodium salt, 1.0 g, 3.33 mmol) were then added and warmed to 458C for
48 h. The mixture was diluted with EtOAc (100 mL), filtered, and con-
centrated under low pressure. The residue was finally purified by flash
chromatography (hexane/EtOAc, 5.5:1) to yield 20b (607 mg, 66%) as a
white syrup. [a]D20 =1.48 (c=0.2 in CHCl3); 1H NMR (400 MHz, CDCl3,
d=191.5 ppm (dd,
J2,F =50.0 Hz, J
3,F =14.0 Hz); 31P NMR (101 MHz,
CDCl3, 258C): d=ꢀ2.79 ppm (s); MS
(DCI): m/z: 946 [M+NH4]+;
ACHTREUNG
HRMS calcd for C45H86O9NFSi4P [M+NH4]+: 946.5101; found: 946.5095.
Data for 15a: [a]D22 =+16.2 (c=0.43 in CHCl3); 1H NMR (400 MHz,
CDCl3, 258C): d=7.37 (m, 10H; ArH), 5.94 (dd, J1,2 =2.7 Hz, J1,P
7.0 Hz, 1H; H-1), 5.04–5.17 (m, 4H; ArCH2), 4.25 (dddd, J1,2 =2.4 Hz,
2,3 =9.1 Hz, J2,F =47.8 Hz, J2,P =3.3 Hz, 1H; H-2), 4.18 (m, 1H; H-3),
4.09 (t, J6,7 =6.5 Hz, 1H; H-6), 3.86 (s, 1H; H-5), 3.82 (t, J3,4 =J4,5
=
J
=
258C): d=7.42–7.27 (m, 10H; C6H5), 5.50 (td, J1,2 =J1,P 7.3 Hz, J1,F
4.0 Hz, 1H; H-1), 5.17–5.05 (m, 4H; OCH2Ph), 4.20 (ddd, J2,F =49.7 Hz,
2,3 =7.1 Hz, 1H; H-2), 3.90 (ddd, J3,F =16.0 Hz, J2,3 =J3,4 =7.1 Hz, 1H; H-
3), 3.88 (dd, J5,6a =4.0 Hz, J6a,6b =11.1 Hz, 1H; H-6a), 3.78 (dd, J5,6b
4.8 Hz, 1H; H-6b), 3.73 (dd, J3,4 =J4,5 =7.1 Hz, 1H; H-4), 3.51 (ddd, J=
4.0 Hz, J=4.8 Hz, J=7.1 Hz, 1H; H-5), 0.98 (s, 9H; tBu), 0.94 (s, 9H;
tBu), 0.90 (s, 9H; tBu), 0.19–0.04 ppm (6s, 18H; CH3Si); 13C NMR
(100 MHz, CDCl3, 258C): d=135.66, 135.58 (Cipso), 128.44–127.88 (m,
C6H5), 95.90 (dd, JP, 1 =27.6 Hz, JF,1 =4.7 Hz, C-1), 92.8 (dd, JF,2 =187.1 Hz,
=
10.0 Hz, 1H; H-4), 3.61 (d, J6,7 =6.5 Hz, 2H; H-7), 0.90–0.96 (4s, 36H;
SitBu), 0.04–0.19 ppm (7s, 24H; SiMe). 13C NMR (101 MHz, CDCl3,
J
258C): d=135.6, 128.5, 128.4”2, 127.9, 127.8, 94.8 (dd, J1,F =5.2 Hz, J1,P
=
=
24.2 Hz), 89.5 (dd, J2,F =191 Hz, J1,P =6.7 Hz), 73.7, 73.6 (d, J3,F =17 Hz),
71.7, 71.5 (d, J4,F =7 Hz), 69.3, 69.2, 64.31, 26.3, 26.2, 26.0, 25.9, 18.6, 18.5,
18.3, 18.2, ꢀ2.5, ꢀ2.7, ꢀ2.8, ꢀ3.3, ꢀ3.4, ꢀ3.8, ꢀ5.4, ꢀ5.5 ppm; 19F NMR
(235 MHz, CDCl3, 258C): d=ꢀ193.9 ppm (dd,
J2,F =44.7 Hz, J3,F =
14.0 Hz); 31P NMR (101 MHz, CDCl3, 258C): d=ꢀ2.64 ppm (s). MS-
ACHTREUNG
(DCI): m/z: 946 [M+NH4]+; HRMS calcd for C45H83O9FSi4P [M+H]+:
J
J
P, 2 =8.3 Hz, C-2), 79.13 (C-5), 76.34 (d, JF,3 =18.3 Hz, C-3), 70.38 (d,
F,4 =5.5 Hz, C-4), 69.36 (d, J=5.6 Hz, CH2Ph), 69.27 (d, J=5.5 Hz,
929.4836; found: 929.4844.
Dibenzyl(2-deoxy-2-fluoro-3,4,6-tri-O-pivaloyl-b-d-gluco-pyranosyl)phos-
phate (19b) and dibenzyl(2-deoxy-2-fluoro-3,4,6-tri-O-pivaloyl-a-d-
manno-pyranosyl)phosphate (19c):
CH2Ph), 62.03 (C6), 18.53, 18.28, 17.97, 18.53, 18.28, 17.97, ꢀ3.11, ꢀ3.14,
ꢀ3.39, ꢀ3.97, ꢀ4.03, ꢀ4.43, ꢀ5.18, ꢀ5.40 ppm; 31P NMR (101 MHz,
CDCl3, 258C): d=ꢀ2.64 ppm (d, JP, 1 7.3 Hz); 19F NMR (235 MHz,
A solution of tri-pivaloyl-d-glucal
16[14] (1 g, 2.50 mmol) in nitromethane (35 mL) was stirred with 4 Š mo-
lecular sieves (2 g) under argon during 15 minutes. Selectfluor (1.8 g,
3.70 mmol) was added at 08C and the reaction mixture was stirred for
20 h at ambient temperature. [15]Crown-5 (1.5 mL, 7.50 mmol) and di-
benzylphosphate (sodium salt, 2.25 g, 7.50 mmol) were then added and
the resulting solution was warmed to 458C for 36 h. The mixture was di-
luted with EtOAc (200 mL), filtered, and concentrated under low pres-
sure. The residue was finally purified by flash chromatography (hexane/
EtOAc, 3:1, 3:2) to yield 19b (990 mg, 57%) and 19c (110 mg, 6%) as
white solids.
CDCl3, 258C): d=ꢀ190.39 ppm (ddd, JF,2 =49.7 Hz, JF,3 =16.0 Hz, JF,1
=
4.0 Hz); elemental analysis calcd (%) for C38H66FO8PSi3: C 58.13, H 8.47;
found C 57.64, H 9.06.
2-Deoxy-1-O-phosphoryl-2-fluoro-l-glycero-b-d-gluco-heptopyranose
(24): Triethylamine (42 mL, 0.309 mmol) was added to a suspension of flu-
orophosphate 14 (125 mg, 0.155 mmol) and Pd/C (10%, 62 mg) in ethyl
acetate (1 mL) and ethanol (2 mL). The mixture was hydrogenated under
H2 atmosphere (1 bar) for 12 h, and filtered through a pad of Celite. The
filtrate was concentrated in vacuo to afford a triethylammonium salt,
which was dissolved in water (1 mL). Tetrabutylammonium hydroxide
(40% in H2O, 1.34 mL, 2.07 mmol) was added to this solution, and the
mixture was stirred at room temperature for 26 h. After neutralization by
IR-120 A (H+) resin, the solution was filtered and concentrated in vacuo.
The residue was dissolved in ethanol (4 mL), and tributylamine (74 mL,
0.310 mmol) was added. Concentration of the mixture in vacuo afforded
a monophosphate 24 (112 mg, quantitative yield) as a syrup.
Data for 19b: White solid, m.p. 1768C; [a]D20 =+238 (c=1.0 in CHCl3);
1H NMR (400 MHz, CDCl3, 258C): d=7.42–7.30 (m, 10H; C6H5), 5.48
(td, J1,2 =J1,P =7.6 Hz, J1,F =3.0 Hz, 1H; H-1), 5.43 (ddd, J3,F =13.7 Hz,
J
3,4 =9.4 Hz, J2,3 =9.1 Hz, 1H; H-3), 5.20–5.08 (m, 5H; OCH2Ph, H-4),
4.47 (ddd, J2,F =50.8 Hz, J1,2 =7.6 Hz, J2,3 =9.1 Hz, 1H; H-2), 4.25 (dd,
5,6a =2.0 Hz, J6a,6b =13.0 Hz, 1H; H-6a), 4.11 (dd, J5,6b =5.0 Hz, 1H; H-
J
6b), 3.90 (ddd, J4,5 =10.0 Hz, J5,6a =2.0 Hz, J5,6b =5.0 Hz, 1H; H-5), 1.22 (s,
9H; CH3), 1.21 (s, 9H; CH3), 1.20 ppm (s, 9H; CH3); 13C NMR
(100 MHz, CDCl3, 258C): d=177.8, 177.0, 176.4 (CO), 135.3, 135.2
(Cipso), 128.6–127.5 (m, C6H5), 95.9 (dd, JP1 =23.7 Hz, JF,1 =4.8 Hz, C-1),
Alternatively, compound 24 was prepared from 15b: Triethylamine
(43 mL, 0.312 mmol) was added to a suspension of fluorophosphate 15b
(145 mg, 0.156 mmol) and Pd/C (10%, 20 mg) in ethyl acetate (1 mL)
and ethanol (2 mL). The mixture was hydrogenated under H2 atmosphere
89.7 (dd, JF,2 =191 Hz, JP, 2 =9.0 Hz, C-2), 73.2 (C-5) ; 71.8 (d, JF,3
=
Chem. Eur. J. 2008, 14, 9530 – 9539
ꢁ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
9537

S. P. Vincent et al.
for 12 h, and filtered through a pad of Celite. The filtrate was concentrat-
ed in vacuo to afford a triethylammonium salt that was dissolved in tetra-
hydrofuran (5 mL). Tetrabutylammonium fluoride (236 mg, 0.90 mmol)
was added to this solution, and the mixture was stirred at room tempera-
ture for 3 h. After neutralization by IR-120 A (H+) resin, the solution
was filtered and concentrated in vacuo. The residue was dissolved in eth-
anol (4 mL), and tributylamine (74 mL, 0.312 mmol) was added. Concen-
tration of the mixture in vacuo afforded a monophosphate 24 (57 mg,
55%) as a bis(tributylammonium) salt. [a]D23 =ꢀ1.78 (c=0.5 in H2O);
dridge, P. A. Corris, C. M. A. Khan, R. Lanzetta, M. Parrilli, Chem.
Eur. J. 2007, 13, 3501–3511.
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1H NMR (400 MHz, D2O, 25 8C): d=5.14 (td, J1,2 =J1,P =7.7 Hz, J1,F
=
2.6 Hz, 1H; H-1), 4.18 (ddd, J1,2 =7.7 HzJ2,3 =8.0 Hz, J2,F =51.0 Hz, 1H;
H-2), 3.98 (td, J6,7a =J6,7b =6.8 Hz, J5,6 =1.5 Hz, 1H; H-6), 3.85 (td, J2,3
8.0 Hz, J3,4 9.2 Hz, J3,F =24.9 Hz, 1H; H-3), 3.72 (m, 2H; H-7), 3.66 (t,
J
3,4 =J4,5 =9.5 Hz, 1H; H-4), 3.53 ppm (dd, J4,5 =9.5 Hz, J5,6 =1.5 Hz, 1H;
H-5); 13C NMR (100 MHz, D2O, 25 8C): d 95.3 (dd, J1,F =4.7 Hz, J1,P
=
23.9 Hz), 92.8 (dd, J2,F =186 Hz, J1,P =8.1 Hz), 75.0, 74.5 (d, J3,F =17 Hz),
68.8 (d, J4,F =7.8 Hz), 68.6, 62.5, 53.1, 25.6, 19.6, 13.1 ppm; 19F NMR
(235 MHz, D2O, 25 8C): d=ꢀ199.2 ppm (dd, J2,F =51.7 Hz, J3,F =14.1 Hz);
31P NMR (101 MHz, D2O, 25 8C): d=0.83 ppm (s); MS (FABꢀ): m/z: 291
[MꢀH]+; HRMS (FABꢀ) calcd for C7H13O9FP [MꢀH]+: 291.0281;
found: 291.0283.
[8]M. D. Burkart, S. P. Vincent, C.-H. Wong, Chem. Commun. 1999,
1525–1526.
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Adenosine 5’-diphospho-2-deoxy-2-fluoro-l-glycero-b-d-gluco-heptopyra-
noside (2): Monophosphate 24 (51 mg, 0.077 mmol) was dissolved in an-
hydrous pyridine under argon atmosphere and concentrated under
vacuum. This azeotropic removal of residual water was repeated three
times. AMP-morpholidate (214 mg, 0.302 mmol) and 1H-tetrazole
(42 mg, 0.603 mmol) was added to the dried monophosphate 24, and the
mixture was left under high vacuum for 24 h. Anhydrous pyridine (2 mL)
was added, and the mixture was stirred under argon atmosphere for 52 h.
After concentration, the residue was precipitated and washed with ethyl
acetate. The resulting solid was purified by preparative HPLC (RP-C18,
isocratic elution: triethylammonium acetate buffer (pH 6.8)/2% acetoni-
trile) to give a mixture of sugar nucleotide 2 and AMP dimer. The mix-
ture was separated by size exclusion chromatography (Sephadex G-15,
elution: water) to furnish sugar nucleotide 2 as a syrup. Repeated lyophi-
lizations of the syrupy product afforded pure sugar nucleotide 2 as a
white solid (31 mg, 56%). 1H NMR (400 MHz, D2O, 25 8C): d=8.25 (s,
1H; adenine), 8.49 (s, 1H; adenine), 6.13 (d, J1’,2’ =6.0 Hz, 1H; H-1’),
5.21 (td, J1,2 =J1,P =7.8 Hz, J1,F =2.6 Hz, 1H; H-1), 4.75 (m, 1H; H-2’),
4.52 (dd, J2’,3’ =5.1 Hz, J3’,4’ =3.5 Hz, 1H; H-3’), 4.39 (t, J3’,4’ =J4’,5’ =3.1 Hz,
1H; H-4’), 4.21 (dd, J4’,5’ =3.2 Hz, Jgem =5.2 Hz, 1H; H-5’), 4.15 (ddd,
[11]L. S. Ni, H. A. Chokhawala, H. Z. Cao, R. Henning, L. Ng, S. S.
Huang, H. Yu, X. Chen, A. J. Fisher, Biochemistry 2007, 46, 6288–
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A. G. Watts, L. L. Lairson, M. Gilbert, D. Lim, W. W. Wakarchuk,
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163–170.
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2000, 39, 4150–4153.
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[15]H. Paulsen, M. Schuller, M. A. Nashed, A. Heitmann, H. Redlich,
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15005.
J
J
1,2 =7.9 Hz, J2,3 =8.7 Hz, J2,F =50.7 Hz, 1H; H-2), 3.91 (dt, J5,6 =1.3 Hz,
6,7a =J6,7b =6.9 Hz, 1H; H-6), 3.78 (dd, J2,3 =J3,4 =9.2 Hz, J3,F =15.0 Hz,
1H; H-3’), 3.69 (dd, J6,7a =7.1 Hz, Jgem =11.6 Hz, 1H; H-7a), 3.68 (dd,
6,7 =7.1 Hz, Jgem =11.6 Hz, 1H; H-7b), 3.63 (t, J3,4 =J4,5 =9.5 Hz, 1H; H-
4), 3.48 ppm (dd, 4,5 =9.8 Hz,
5,6 =1.5 Hz, 1H; H-5); 13C NMR
(101 MHz, D2O, 25 8C): d=181.9, 156.0, 153.4, 153.3, 95.6 (dd, JP1
J
J
J
=
22.6 Hz, JF1 =4.4 Hz, C1), 92.4 (dd, JF2 =184 Hz, JP2 =8.8 Hz, C2), 87.2,
84.3 (d, J=9.4 Hz,), 75.1, 74.6, 74.3 (d, JF3 =17.3 Hz, C3), 70.8, 68.7 (d,
J
F4 =7.8 Hz, C4), 68.5, 65.6 (d, J=5.6 Hz, C5’), 62.4; 19F NMR (235 MHz,
D2O, 25 8C): d ꢀ199.9 ppm (dd, J2,F =50.8 Hz, J3,F =13.9 Hz); 31P NMR
(101 MHz, D2O, 25 8C): d=ꢀ11.3 (d, J=22.2 Hz), ꢀ13.3 ppm (d, J=
22.2 Hz); MS-ESI: m/z: 620 [MꢀH]+; ESI-HRMS calcd for
C17H25N5O15FP2 [MꢀH]+: 620.0806; found: 620.0817.
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Acknowledgement
This program was supported by Start-up funds Mutabilis S.A. (post-doc
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Received: June 26, 2008
Published online: October 2, 2008
Chem. Eur. J. 2008, 14, 9530 – 9539
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9539