α-Halogenated oxaphosphinanes: Synthesis, unexpected reactions and evaluation as inhibitors of cancer cell proliferation

Article abstract of DOI:10.1016/j.ejmech.2015.09.027

This paper describes the preparation and the biological evaluation of α-halogenated oxaphosphinanes. These halogen derivatives were synthetized from a short and stereoselective synthetic sequence starting by previously described hydroxy-precursors 1 and 2 with respectively a glucose and mannose-like configuration. The in vitro biological tests of these unnatural halogenated phosphinosugars, on several cell lines, highlighted, for some of them, their antiproliferative and anti migration and invasion properties at nanomolar concentration.α-Halogenated (I, Br, Cl) oxaphosphinanes were obtained stereoselectively from a two-step sequence, via a phase transfer catalyzed reaction.An unusual rearrangement was observed leading to furanosylphosphinic acid.In vitro biological tests on several cell lines, highlighted their antiproliferative properties at nanomolar concentration.

Full text of DOI:10.1016/j.ejmech.2015.09.027

European Journal of Medicinal Chemistry 104 (2015) 33e41
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Research paper
a-Halogenated oxaphosphinanes: Synthesis, unexpected reactions
and evaluation as inhibitors of cancer cell proliferation
,
Rachida Babouri a b, Marc Rolland e, Odile Sainte-Catherine c, Zahia Kabouche b,
,
***
d
a
,
, *
Marc Lecouvey c , Norbert Bakalara , Jean-Noel Volle **, David Virieux a
,
€
Jean-Luc Pirat a
a ICG MontpelliereUMR 5253, Equipe AM2N, ENSCM, 8, Rue de l'Ecole Normale, 34296 Montpellier CEDEX 5, France
Universite Mentouri-Constantine, Departement de chimie, Laboratoire d’Obtention de Substances Therapeutiques (LOST), Campus Chaabet Ersas, 25000
b
ꢀ
ꢀ
ꢀ
Constantine, Algeria
c
ꢀ
ꢀ
Universite Paris 13, Sorbonne Paris Cite, CSPBAT, CNRS UMR 7244, 74, Rue Marcel Cachin, F-93017 Bobigny, France
d INSERM U-1051, Institut des Neurosciences de Montpellier, 80 Rue Augustin Fliche, 34091 Montpellier, France
e
ꢀ
ꢀ
Institut Europeen des Membranes, cc047 Universite de Montpellier 2, 34095 Montpellier, France
a r t i c l e i n f o
a b s t r a c t
Article history:
This paper describes the preparation and the biological evaluation of a-halogenated oxaphosphinanes.
Received 14 June 2015
Received in revised form
19 September 2015
Accepted 21 September 2015
Available online 28 September 2015
These halogen derivatives were synthetized from a short and stereoselective synthetic sequence starting
by previously described hydroxy-precursors 1 and 2 with respectively a glucose and mannose-like
configuration. The in vitro biological tests of these unnatural halogenated phosphinosugars, on several
cell lines, highlighted, for some of them, their antiproliferative and anti migration and invasion prop-
erties at nanomolar concentration.
© 2015 Elsevier Masson SAS. All rights reserved.
Keywords:
a
-Halogenated oxaphosphinanes
Phosphinosugars
Phase-transfer catalysis
Triflate halogen exchange
Sigmatropic rearrangement
Antiproliferative properties
1. Introduction
primary cultures, some of them exhibited antimigratory properties
on C6 and SNB75 cell lines as well as on Gli 4 and Gli 7 brain cancer
Glioblastoma are the most frequent brain tumors in humans [1].
The traditional treatments of these cancers, i.e. resection, followed
by radiotherapy and chemotherapy with Temozolomide, have a
limited efficacy and the median survival rarely exceeds 15 months
[2]. A family of phosphorus glycomimetics, has been described by
our groups for antiproliferative, anti-migratory and anti-invasive
effects on several glioblastoma cell lines [3,4]. The discovery of
these original structures may afford a timely therapeutic response
for patients. Indeed if the antiproliferative efficiency of these
primary cultures in nanomolar range [4].
Thousands of natural halogenated organic molecules were
already discovered, mainly are organochlorines [5e7] and/or bro-
mines [6e8], and to a lesser extent natural compounds incorpo-
rating iodine [9], or fluorine atoms [10,11]. All of them exhibit
interesting and noteworthy biological properties and cytotoxicity is
commonly reported. Njardarson highlighted the preeminence of
halogen elements featured in commercial drugs approved by the
FDA [12]. In this context, the contribution of fluorine is typically
well documented. This relatively small and highly electronegative
element has generally a high impact on pharmacological parame-
ters, modifying pKa, lipophilicity and even conformation [13,14].
Consequently, metabolic stability and increased binding affinity by
direct interaction of fluorine atom with the protein or by modifi-
cation of the polar surface of other groups are often observed.
In order to complete the [1,2]-oxaphosphinane structure-activ-
ity relationship (SAR), we investigated the stereoselective
phosphinosugars are in the mM ranges on brain cancer cell lines and
* Corresponding author.
** Corresponding author.
*** Corresponding author.
E-mail addresses: marc.lecouvey@univ-paris13.fr (M. Lecouvey), jean-noel.
volle@enscm.fr (J.-N. Volle), david.virieux@enscm.fr (D. Virieux).
http://dx.doi.org/10.1016/j.ejmech.2015.09.027
0223-5234/© 2015 Elsevier Masson SAS. All rights reserved.

34
R. Babouri et al. / European Journal of Medicinal Chemistry 104 (2015) 33e41
preparation of halogenated analogues 3 and 4 starting from the
enantiopure oxaphosphinane 1 and 2 respectively considered as
having a glucose-like and a mannose-like configuration. Besides,
the preparation of fluorine analogues to study the in vivo bio-
distribution of oxaphosphinanes 1 and 2 was very attractive, due to
the possibility to introduce 18F isotope for imagery by positron
emission tomography (PET) [14] Fig. 1.
2. Chemistry
The synthesis of the 3-hydroxyoxaphosphinanes 1 and 2 was
previously described using a one-step additionecyclization reac-
tion of ethyl phenylphosphinate to 2,3,5-tri-O-benzyl-D-arabino-
Fig. 2. Stereocontrolled approach for preparation of halogenated oxaphosphinane
3aed and 4aed.
furanose under basic activation [3,15]. Stereoselective preparation
of halogenated-derivatives 3aed and 4aed from glucose-like and
mannose-like oxaphosphinanes 1 and 2, may be accomplished by a
modified version of the Finkelstein reaction. The formation of tri-
flate derivatives 5 and 6 which generally occurs with retention of
configuration could be followed by halogen-triflate exchange. This
reaction proceeds generally through a SN2 process with inversion of
configuration Fig. 2.
Introduction of triflate on
a-hydroxy-phosphonate is already
referred, and can be achieved in presence of triflic anhydride with
pyridine [16,17], or 2,6-lutidine [18,19] as base. However, a rapid
screening of literature did not allow to find any procedure where
stereocontrol is required or where the leaving group is a substitu-
ent of a phosphorus heterocycle. We already published the prepa-
ration of a diastereomeric mixture of triflate derivatives 5 and 6
from a 60:40 ratio of phosphinosugars 1 and 2 using a large excess
of triflic anhydride and pyridine [3]. Nevertheless, the purification
of each diastereoisomer 5 and 6 by chromatography on silica
revealed very intricate. Therefore all triflate derivatives were pre-
pared preferentially from the enantiopure precursors 1 and 2.
Starting from glucose-like oxaphosphinane 1, triflate derivative 5
was obtained quantitatively (98%). By contrast, the mannose-like
diastereomer 2 gave, in the same conditions, moderate yield of
the expected triflate 6 (44%). Surprisingly 2,6-lutidine has a dra-
matic effect on stereoselectivity. Indeed, inversion of configuration
was observed affording exclusively triflate 5 (96% from 31P-NMR
and 53% isolated yield). This unexpected stereoselectivity might be
explained by the difference of ion pair interactions between pyr-
idinium/triflate and lutidinium/triflate. Indeed, the sterically hin-
dered lutidinium cation would prevent an intimate electrostatic
interaction with its counter anion, allowing to the free triflate anion
a nucleophilic displacement of the preformed derivative 6 favoring
finally the thermodynamic triflate 5 (Scheme 1).
Scheme 1. Preparation of triflates 5 and 6 from oxaphosphinanes 1 and 2.
Similarly, the diastereomer 4b was isolated in 67% yield from the
reaction of epimer 6 (entry 5). Monocrystals of brominated 4b have
been obtained by crystallization from a mixture of acetone and
hexanes. X-ray data showed that bromide derivative 4b adopted a
chair conformation with the bromine atom laying in equatorial
position confirming that the reaction occurred through a clean SN2
pathway (Fig. 3). Chlorinated oxaphosphinanes 3c and 4c were
obtained respectively in 62% and 35% yields by reaction of the tri-
flates 5 and 6 with stoichiometric quantity of tetraethylammonium
chloride in acetonitrile (entries 6 and 7).
This methodology was consecutively applied for the synthesis of
the fluoride derivative 3d from glucose-like oxaphosphinane 5
using potassium fluoride (entry 8). Instead of the expected triflate-
fluorine exchange, a rearrangement occurred giving two different
compounds (Scheme 2). They were characterized by two doublets
respectively at 46.2 ppm and 46.0 ppm and strong 31Pe19F coupling
constants in 31P-NMR. With values of 1058 and 1048 Hz, coupling
Each diastereomeric triflates 5 and 6 were converted into the
corresponding iodides 3a and 4a in good yields, respectively 62%
and 70% by treatment with 4 equivalents of potassium iodide in
acetonitrile at 80 ꢀC (Table 1, entries 1 and 2) [20].
1
constants were unambiguously attributed to a JPF. These PeF in-
termediates were rapidly hydrolyzed by addition of water in the
reaction mixture giving only one signal centered at 21.4 ppm in 31P-
NMR. Fluorine derivatives were identified as the diastereomeric
mixture of 2-fluorophosphino tetrahydrofurans 7a and 7b. The
action of water led to the corresponding furanosylphosphinic acid 8
as a single enantiomer consecutively to the loss of asymmetric
phosphorus center. Mechanistically, the chemoselectivity observed
during the process can be rationalized using the hard-soft-acid-
base theory (HSAB). Fluoride anion considered as a “hard” nucle-
ophile interacted preferentially with the “hardest” electrophilic
site, i.e. phosphinolactone group. We excluded the nucleophilic
substitution of fluoride to the phosphorus atom. If the reaction
proceeded by this SN(P) reaction only one stereoisomer would be
obtained. An alternate mechanism might be the formation of the
pentacoordinated phosphorane (Scheme 2). Configurational
Bromination of triflate 5 was accomplished in low yield from the
reaction of potassium bromide and tetraethylammonium bromide
(10 mol %) as phase-transfer agent [21]. Under these conditions
only 21% of the bromide derivative 3b was isolated after 24 h at
80 ꢀC (entry 3). After optimization using stoichiometric amounts of
tetraethylammonium bromide (entry 4), yield of 52% was obtained.
Fig. 1. Oxaphosphinane 1e2 and targeted halogenated analogues 3 and 4.

R. Babouri et al. / European Journal of Medicinal Chemistry 104 (2015) 33e41
35
Table 1
Formation of halogenated oxaphosphinanes 3, 4 and compounds 8 and 9.
Entry
Precursor
Reaction conditions
Product
Yield %
1
2
3
4
5
6
7
8
9
10
5
6
5
5
6
5
6
5
6
KI (4 eq.), MeCN, 80 ꢀC, 2 h
3a
4a
3b
3b
4b
3c
4c
8
62b
70b
21b
52b
67b
62b
35.5b
KI (4 eq.), MeCN, 80 ꢀC, 1.5 h
KBr (4 eq.), Et4NBr (0.1 eq.), MeCN, 80 ꢀC, 24 h
Et4NBr (1 eq.), MeCN, 80 ꢀC, 3 h
Et4NBr (1 eq.), MeCN, 80 ꢀC, 2 h
Et4NCl (1 eq.), MeCN, 80 ꢀC, 1 h
Et4NCl (1 eq.), MeCN, 80 ꢀC, 3 h
KF (4 eq.), MeCN, 80 ꢀC, 5 h
84b (95a)
41a
KF (6 eq.), DMSO, 100e115 ꢀC, 4 h
CsF (4 eq.), DMSO, 95 ꢀC, 1 h 15
9
9
3a
80b (95a)
a
Estimated by 31P NMR from the crude mixture with a sealed capillary tube containing DMSO-d6 as lock solvent.
Isolated yield after purification on silica column.
b
(Scheme 2, Pathway A), 2) or by sigmatropic rearrangement
affording diastereomers 7a and 7b (Scheme 2, Pathway B).
The other diastereomeric triflate 6 also gave an unexpected
product on treatment with potassium fluoride in dimethylsulfoxide
(entry 9) which was clearly identified as the oxaphosphinene 9. The
formation of this structure can be explained by the basic character
of fluoride, leading preferentially to an elimination process rather
than a nucleophilic displacement of iodide atom. Suitable mono-
crystals for X-ray studies were obtained from slow crystallization in
ethyl acetate and hexane confirming the presence of the enol ether
functional group (Scheme 3). Formation of oxaphosphinene 9 was
deeply improved in yield up to 80% by employing cesium fluoride as
fluorine source and iodooxaphosphinane 3a rather than triflate 6
(entry 10).
A common reagent used for transformation of alcohols into
fluorides is diethyl amino sulfur trifluoride (DAST) [17,23]. Direct
fluorination of glucose and mannose-like oxaphosphinanes 1 and 2
were tested using DAST in dichloromethane. Compound 1 failed to
give the fluorine derivative 3d whatever the conditions. Never-
theless, the glucose-like fluorooxaphosphinane 4d was isolated by
column chromatography on silica in 3% yield (Scheme 4).
Fig. 3. X-ray diffraction diagram of bromooxaphosphinane 4b.
flexibility in pentavalent compounds, through stereomutation
mechanism is well established and could explain the epimerization
of the phosphorus atom [22]. At this level, the resulting phos-
phoranes could collapse following two pathways: 1) by cleavage of
oxygen-phosphorus bond and oxaphosphinane ring-opening. Then
the resulting alkoxide attacked the electrophilic carbon through a
SN2 reaction, leading to both diastereomers 7a and 7b, which upon
hydrolysis furnished the enantiopure furanosylphosphinic acid 8
Scheme 2. Attempt of nucleophilic fluorination of triflate 5.

36
R. Babouri et al. / European Journal of Medicinal Chemistry 104 (2015) 33e41
Scheme 3. Synthesis and X-ray structure of oxaphosphinene 9.
3. Biological evaluation
MDAMB435 cell lines on matrix made of fibronectin, vitronectin or
laminin in the nM range. The compound 4c and 4a displayed
moderate anti-migratory activity of B16F10 and MDAMB435 cells
respectively on vitronectin but these compounds cause cell cyto-
toxicity. Best migration inhibition of B16F10 cells by 3b on laminin
gave Ki value of 10 nM.
In the presence of HGF in the lower part of the Boyden migration
chamber, the B16F10 and MDAMB435 cells invaded the Matrigel
and were visualized at lower surface of the membrane. a-haloge-
3.1.
a
-Halogenated oxaphosphinanes effects on cell viability
The -halogenated oxaphosphinanes were screened on a panel
a
of six cancer cell lines. The panel comprised human breast adeno-
carcinoma (pleural metastasis) cell line (MDAMB231), human
melanoma cell lines (MDAMB435) and mouse melanoma cell lines
(B16F10), human colorectal carcinoma cell line (CaCo2), human
hepatocarcinoma cell line (HuH7), prostatic carcinoma cell line
(DU145). To evaluate the antiproliferative activity of these a-halo-
genated oxaphosphinanes and related analogues, we have used a
MTT test. Interestingly, among the six cancer lines tested only the
nated oxaphosphinanes reduced the invasion of the cells at nano-
molar range but the maximum of inhibition did not exceed 70% for
B16F10 cells and 50% for MDAMB435 cells.
human colorectal adenocarcinoma does not respond to the
a-
4. Conclusion
halogenated oxaphosphinanes (Table 2). Human (MDAMB435) and
mouse (B16F10), melanoma cell lines proliferation inhibition
reached 70% inhibition at the highest concentration tested. DU145
and HuH7 cell lines proliferations were only inhibited by 50%.
MDAMB231 cell line proliferation was inhibited by 30%. It has to be
noticed that for a given cell line the maximum inhibition of pro-
liferation was almost the same for seven of the eight a-halogenated
oxaphosphinanes but with different IC50 values. Only the fluori-
nated one 4d was not active against MDAMB231 and DU145 cell
In conclusion, we succeeded to obtain stereoselectively the
desired halogen-based oxaphosphinanes from
a
two-step
sequence. In contrast to the other halogens, introduction of fluo-
rine failed when performed by this triflate/halogen exchange and
the reaction was deeply affected by the stereochemistry of the
triflate group: when triflate layed in equatorial position, an unusual
rearrangement was observed leading to furanosylphosphinic acid 8
whereas the formation of the enol ether 9 was observed from the
other epimer both in high yields. The glucose-like fluorinated
oxaphosphinane 4d was obtained by direct fluorination using DAST.
We consecutively demonstrated that these oxaphosphinanes
were active against melanoma, epidermoid car, hepatocarcinoma,
prostatic carcinoma and breast adenocarcinoma cell lines. Activities
on these cancer cell lines did not depend on the nature of the
halogen atom. By contrast with our previous results on the hy-
droxyl derivatives 1 and 2, no stereoselectivity was observed.
lines. The other
a-halogenated oxaphosphinanes and the non-
halogenated one (compound 9) exhibited IC50's in the 15e500 nM
range.
3.2.
a-Halogenated oxaphosphinanes effects on cell migration and
invasion
To study the impact of compounds 3 aec and 4 aed on B16F10
Although
a-halogenated oxaphosphinanes exhibited anti-
and MDAMB435 cell lines migration according to the matrix
context, we performed all comparisons of compoundematrix
context and measured the serum motility response using a 2D-
migration assay over the course of 24 h in presence and absence of
the glycoside mimetics (Table 3).
proliferative activity in the nM range for MDAMB231, MDAMB435,
B16F10, HuH7, DU145 cell lines, inhibition did not reach 100% of cell
viability at the highest concentration tested (100
pothesis could be that -halogenated oxaphosphinanes are more
cytostatic than cytotoxic. Alternatively, this observation may reflect
cell heterogeneity concerning either the expression of the -halo-
genated oxaphosphinanes targets or the impact of the -haloge-
mM). One hy-
a
As shown in Table 3, most of the synthetic a-halogenated oxa-
phosphinanes strongly inhibited the migration of B16F10 and
a
a
nated oxaphosphinanes on these targets. In a second screening
step, we tested the selected phostines 3aec and 4aed for their
migration inhibition activity against B16F10 and MDAMB435 cell
lines. As the cytotoxicity, the position of halogen on the carbon 2
didn't change Ki values. We observed for the two epimers the same
range for the migration inhibition. The nature of halogen is not a
determining parameter because variations of Ki values between 16
and 50 nM on fibronectin, 10 and 42 nM on laminin are not sig-
nificant. In contrast, the nature of halogen plays a more important
role on vitronectin migration inhibition. Ki value (380 nM)
decreased drastically for B16F10 migration inhibition if the halogen
is a chlorine (compound 4c). This effect was also observed for
MDAMB435 migration inhibition with the compound 4a bearing
iodine on
a position. These experimental data suggest that a-
Scheme 4. Direct fluorination of glucose and mannose-like oxaphosphinanes 1 and 2
by DAST.
halogenated oxaphosphinanes affect proliferation, migration and

R. Babouri et al. / European Journal of Medicinal Chemistry 104 (2015) 33e41
37
Table 2
Antiproliferative Values (IC50, nM) of the oxaphosphinanes on MDAMB231, MDAMB435 (Cell Line Obtained from Breast Cancer Tissue), B16F1 (Cell Lines Obtained from Skin
Cancer Tissues), Caco2 (Cell Line Obtained from Colon Cancer Tissue), HuH7 (Cell Line Obtained from Intestine Cancer Tissue), DU145 (Cell Line Obtained from Prostate Cancer
Tissue).
IC50 values (nM)
MDAMB231a
MDAMB435b
B16F10c
Caco2
HuH7d
DU145e
Compounds
3a
4a
3b
4b
6c
4c
9
466 ( 2)
478 ( 2)
445 ( 1)
432 ( 135)
404 ( 1)
359 ( 14)
286 ( 1)
NA
0.55 ( 0.08)
0.3 ( 0.01)
0.2 ( 0.01)
0.35 ( 0.01)
1.1 ( 0.02)
1.6 ( 0.01)
0.52 ( 0.001)
1.45 ( 0.01)
7.7 ( 0.01)
4 ( 0.01)
4.6 ( 0.01)
3.8 ( 0.01)
8 ( 0.02)
7.7 ( 0.02)
4.4 ( 0.02)
1.7 ( 0.02)
20,500
28,600
24,718
29,500
26,200
24,800
28,400
NA
229 ( 1)
13 ( 0.2)
11.6 ( 0.1)
15.8 ( 0.1)
270 ( 1)
1170 ( 4)
37.5 ( 0.1)
12.1 ( 0.1)
215 ( 3)
104 ( 0.2)
102 ( 0.2)
86.5 ( 0.5)
15.5 ( 0.2)
226 ( 0.3)
116 ( 0.2)
NA
4d
a
The maximum inhibition of cell proliferation was 30% at 100
M.
The maximum inhibition of cell proliferation was 60% at 100
to 100 M.
The maximum inhibition of cell proliferation was 80% at 100
0.1 nM to 100 M.
The maximum inhibition of cell proliferation was 55% at 100
to 100 M.
The maximum inhibition of cell proliferation was 45% at 100
to 100 M. The remaining cells appeared to be resistant.
m
M. The IC50 has been calculated from 0 to 35% of inhibition for compound concentrations ranging from 10 nM
to 100
m
b
mM. The IC50 has been calculated from 0 to 60% of inhibition for compound concentrations ranging from 10 nM
m
c
mM. The IC50 has been calculated from 0 to 80% of inhibition for compound concentrations ranging from
m
d
m
M. The IC50 has been calculated from 0 to 55% of inhibition for compound concentrations ranging from 10 nM
M. The IC50 has been calculated from 0 to 55% of inhibition for compound concentrations ranging from 10 nM
m
e
m
m
point were measured on a Büchi B-540 apparatus. Spectrums 1H,
Table 3
19F, 31P and 13C were recorded on a Bruker DRX 400 MHz spec-
trometer operating respectively at frequency of 400 MHz, 188 MHz,
162 MHz and 101 MHz. All NMR experiments performed on phos-
phorus are indicated uncoupling of hydrogen. In order to facilitate
NMR description of oxaphosphinane, proton and carbon of ring was
numbered from right to left and started by adjacent position of
phosphorus atom. The spectrometer used for high resolution mass
spectra was SYNAPT G2-S of Water. Intensities reflections were
measured with an Xcalibur, Sapphire 3, Gemini diffractometer [24]
Antimigratory values (Ki) of
MDAMB435 cell lines.
a
-halogenated oxaphosphinanes on B16F10 and
Strain
Products
Kia (nM) support
FN
LN
VN
INVb
B16F10
3a
4a
3b
4b
3c
4c
4d
16
20
46
30
49
18
22
1
1
1
1
1
1
1
17
16
10
20
19
13
16
1
1
1
1
1
1
1
44
35
21
50
34
380
40
1
1
1
1
1
29
37
17
32
35
37
33
1
1
1
1
1
1
1
1
(graphite monochromated CuK
a
radiation (k ¼ 1.54184 Å), CCD-
1
detector, scanning). Data reduction was performed with CrysA-
u
Strain
Products
Ki (nM) support
lisPro [25], and an empirical absorption correction was applied.
Equivalent reflections, other than Friedel pairs were merged. The
structures were solved by direct method using the SHELXS and
refined using SHELXL [25], with full-matrix least-squares refine-
ment against F2 in anisotropic approximation for non-hydrogen
atoms. H atoms were treated by a mixture of independent and
constrained refinement. Refinement of the absolute structure Flack
parameters [26], while the Hooft analysis [27], gave absolutes pa-
rameters which confidently confirms that the refined coordinates
represent the true enantiomorph.
FN
LN
VN
INVd
MDAMB435
3a
4a
3b
4b
3c
4c
4d
29
1
1
1
1
1
1
1
25
23c
34
42
23c
32
34
1
1
1
1
1
1
1
43
101
46
1
28
35
13
30
36
35
31
1
1
1
1
1
1
1
28c
39
1
1
1
1
1
28c
28c
36
78
41c
52
28c
66
FN: fibronectin; LN: laminin; VN: vitronectin; INV: invasivity.
a
Ki estimation was determined with serf/cell and maps software using the Hill
equation.
b
c
Maximum inhibition does not exceed 70%.
Maximum inhibition does not exceed 90%.
Maximum inhibition does not exceed 50%.
5.1.2. (2Sp,3S,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-O-
d
trifluoromethane sulfonyl-2-phenyl-2-oxo-2l
5-[1,2]-
oxaphosphinane 5
Under N2 and at ꢁ70 ꢀC, trifluoromethanesulfonic anhydride
invasion. Our study provides a novel type of small molecule ther-
apeutic agents that aim to block tumor progression and the
metastasis formation.
(222 mL, 1.32 mmol) was added dropwise to a solution of 1 (0.60 g,
1.1 mmol) and pyridine (178
mL, 2.2 mmol) in dichloromethane
(3.6 mL). After 1 h at 0 ꢀC, the organic layer was washed twice with
water, dried over sodium sulfate, filtered and concentrated under
vacuum to give 5 as a white solid (0.73 g, 98%), m.p. 135.8e136.4 ꢀC.
5. Experimental
31P NMR (CDCl3):
(CDCl3):
d
28.07 (s). 19F NMR (CDCl3):
d
ꢁ75.03 (s). 1H NMR
2
3
5.1. Chemistry
d
3.78 (dd, JHH ¼ 11.2 Hz, JHH ¼ 2.0 Hz, 1H, OCH2), 3.98
(ddd, 2JHH ¼ 11.2 Hz, 4JHP ¼ 2.6 Hz, 3JHH ¼ 2.4 Hz,1H, OCH2), 4.19 (dd,
3
3
5.1.1. General considerations
3JHH ¼ 9.8 Hz, JHH ¼ 9.5 Hz, 1H, 3CH), 4.45 (ddd, JHH ¼ 10.5 Hz,
3
2
Before use, all solvents were dried to help of MBRAUN solvent
purification system or by drying according to current method, and
stored under nitrogen. Reactions were monitored by 31P NMR using
DMSOed6 as internal reference. Purifications by column chroma-
3JHH ¼ 9.5 Hz, JHP ¼ 3.1 Hz, 1H, 2CH), 4.53 (d, JHH ¼ 12.0 Hz, 1H,
OCH2), 4.62 (d, 2JHH ¼ 12.0 Hz, 1H, OCH2), 4.64 (dddd, 3JHH ¼ 9.8 Hz,
3
3
3JHP ¼ 4.2 Hz, JHH ¼ 2.4 Hz, JHH ¼ 2.0 Hz, 1H, 4CH), 4.68 (d,
2JHH ¼ 10.7 Hz,1H, OCH2), 4.89 (d, 2JHH ¼ 10.7 Hz,1H, OCH2), 4.90 (d,
2
tography were performed on silica gel (60 AC. 35e70
m
m). Melting
2JHH ¼ 10.4 Hz, 1H, OCH2), 4.98 (d, JHH ¼ 10.4 Hz, 1H, OCH2), 5.08

38
R. Babouri et al. / European Journal of Medicinal Chemistry 104 (2015) 33e41
3
(dd, 3JHH ¼ 10.5 Hz, 2JHP ¼ 1.2 Hz, 1H, 1CH), 7.15e7.17 (m, 2H, CHar),
7.29e7.37 (m, 13H, CHar), 7.56e7.61 (m, 2H, CHar), 7.70e7.74 (m, 1H,
126.61 (1 transition, Car), 127.56, 127.76 (d, JCP ¼ 13.9 Hz, CHar),
128.01, 128.03, 128.06, 128.21, 128.40, 128.45, 128.52, 133.12 (d,
2JCP ¼ 9.6 Hz, CHar), 133.46 (d, 4JCP ¼ 2.7 Hz, CHar), 137.22 (s, CarBn),
137.89 (s, CarBn), 138.18 (s, CarBn). HRMS (m/z) calcd for C32H33IO5P:
655.1110. Found: 655.1105.
CHar), 7.87e7.92 (m, 2H, CHar). 13C NMR (CDCl3):
d 67.88 (d,
2
3JCP ¼ 9.4 Hz, BnOCH2), 73.50 (s, PhCH2), 75.51 (d, JCP ¼ 5.9 Hz,
4CH), 75.64 (s, PhCH2), 76.39 (s, PhCH2), 78.48 (s, 3CH), 80.32 (d,
2JCP ¼ 4.3 Hz, 2CH), 81.42 (d, JCP ¼ 96.5 Hz, 1CH), 117.96 (q,
1
1JCF ¼ 319.6 Hz, CF3), 124.82 (d, 1JCP ¼ 145.1 Hz, Car), 127.58, 127.67,
3
127.92, 128.02, 128.37, 128.52, 129.03 (d, JCP ¼ 14.2 Hz, CHar),
5.1.5. (2Sp,3R,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-
132.42 (d, 2JCP ¼ 10.8 Hz, CHar), 134.49 (d, 4JCP ¼ 2.9 Hz, CHar), 137.01
(s, CarBn), 137.31 (s, CarBn), 137.54 (s, CarBn). HRMS (m/z) calcd for
iodo-2-phenyl-2-oxo-2l
5-[1,2]oxaphos phinane 4a
Under nitrogen, potassium iodine (0.077 g, 0.46 mmol) was
added to a solution of 6 (0.078 g, 0.12 mmol) in acetonitrile (3 mL).
The reaction mixture was stirred at 80 ꢀC for 1.5 h, and solvent was
evaporated under vacuum. A normal phase chromatography on
silica gel using a mixture of n-heptane/ethyl acetate (60:40) as
eluent, afforded compound 4a as a white solid (0.053 g, 70%), m.p.
C
33H33F3O8PS: 677.1586. Found: 677.1590.
5.1.3. (2Sp,3R,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-O-
trifluoromethane sulfonyl-2-phenyl-2-oxo-2l
5-[1,2]-
oxaphosphinane 6
On the same manner than above and after chromatography
column on silica gel using a mixture of n-heptane/ethyl acetate
(60:40) as eluent, compound 6 was obtained as a colorless oil
127e128 ꢀC. 31P NMR (CDCl3):
d
34.52 (s). 1H NMR (CDCl3):
d
3.69
2
3
(dd, JHH
¼
11.2 Hz, JHH
¼
2.0 Hz, 1H, OCH2), 3.81 (dd,
3JHH ¼ 11.5 Hz, JHP ¼ 4.2 Hz, 1H, 1CH), 3.91 (dt, JHH ¼ 11.2 Hz,
2
2
(0.33 g, 44%). 31P NMR (CDCl3):
d
29.36 (s). 19F NMR (CDCl3):
3JHH ¼ 2.6 Hz, JHP ¼ 2.6 Hz, 1H, OCH2), 3.98 (dd, JHH ¼ 9.9 Hz,
4
3
2
3
3
d
ꢁ75.21 (s). 1H NMR (CDCl3):
d
3.68 (dd, JHH ¼ 11.2 Hz,
3JHH ¼ 9.2 Hz, 1H, 3CH), 4.20 (ddd, JHH ¼ 11.5 Hz, JHH ¼ 9.2 Hz,
3JHH ¼ 2.0 Hz, 1H, OCH2), 3.83 (ddd, JHH ¼ 11.2 Hz, JHH ¼ 3.0 Hz,
3JHP ¼ 2.3 Hz, 1H, 2CH), 4.46 (d, 2JHH ¼ 12.0 Hz, 1H, OCH2), 4.55 (d,
2
3
4JHP ¼ 2.9 Hz, 1H, OCH2), 4.13 (dd, 3JHH ¼ 9.9 Hz, 3JHH ¼ 9.8 Hz, 1H,
2JHH ¼ 12.0 Hz, 1H, OCH2), 4.56 (m, JHH ¼ 9.9 Hz, JHP ¼ 4.1 Hz,
3
3
3CH), 4.38 (dd, JHH ¼ 9.8 Hz, JHH ¼ 2.4 Hz, 1H, 2CH), 4.48 (d,
2JHH ¼ 12.3 Hz, 1H, OCH2), 4.50 (d, 2JHH ¼ 11.00 Hz, 1H, OCH2), 4.51
(dddd, 3JHH ¼ 9.9 Hz, 3JHP ¼ 3.1 Hz, 3JHH ¼ 3.0 Hz, 3JHH ¼ 2.0 Hz, 1H,
4CH), 4.53 (d, 2JHH ¼ 11.4 Hz, 1H, OCH2), 4.55 (d, 2JHH ¼ 12.3 Hz, 1H,
OCH2), 4.80 (d, 2JHH ¼ 11.0 Hz, 1H, OCH2), 4.83 (d, 2JHH ¼ 11.4 Hz, 1H,
OCH2), 5.37 (dd, 2JHP ¼ 4.7 Hz, 3JHH ¼ 2.4 Hz, 1H, 1CH), 7.04e7.06 (m,
2H, CHAr), 7.14e7.30 (m, 13H, CHAr), 7.41e7.46 (m, 2H, CHAr),
3JHH ¼ 2.6 Hz, JHH ¼ 2.0 Hz, 1H, 4CH), 4.62 (d, JHH ¼ 10.9 Hz, 1H,
3
3
3
2
OCH2), 4.83 (d, 2JHH ¼ 10.9 Hz,1H, OCH2), 4.85 (d, 2JHH ¼ 10.1 Hz,1H,
2
OCH2), 4.94 (d, JHH ¼ 10.1 Hz, 1H, OCH2), 7.13e7.15 (m, 2H, CHar),
7.19e7.33 (m, 13H, CHar), 7.42e7.47 (m, 2H, CHar), 7.56e7.59 (m, 1H,
CHar), 7.81e7.86 (m, 2H, CHar). 13C NMR (CDCl3):
d 20.63 (d,
1JCP ¼ 81.2 Hz, 1CH), 68.40 (d, JCP ¼ 9.3 Hz, BnOCH2), 73.47 (s,
3
PhCH2), 75.47 (s, PhCH2), 75.53 (d, JCP ¼ 5.5 Hz, 4CH), 76.28 (s,
2
7.57e7.61 (m, 1H, CHAr), 7.79e7.84 (m, 2H, CHAr). 13C NMR (CDCl3):
PhCH2), 79.30 (s, 3CH), 82.22 (d, JCP ¼ 1.2 Hz, 2CH), 126.61 (d,
2
3
d
68.46 (d, JCP ¼ 9.0 Hz, BnOCH2), 73.12 (s, PhCH2), 73.21 (d,
1JCP ¼ 146.9 Hz, Car), 127.60, 127.61, 127.79, 127.94, 128.04, 128.09,
2JCP ¼ 1.6 Hz, 3CH), 73.37 (s, PhCH2), 75.86 (s, PhCH2), 76.55 (d,
128.45, 128.53, 128.73 (d, JCP ¼ 13.9 Hz, CHar), 132.36 (d,
3
3JCP ¼ 6.2 Hz, 4CH), 79.05 (d, JCP ¼ 3.4 Hz, 2CH), 79.73 (d,
2JCP ¼ 10.1 Hz, CHar), 133.64 (d, 4JCP ¼ 2.9 Hz, CHar), 137.48 (s, CarBn),
137.64 (s, CarBn), 137.84 (s, CarBn). HRMS (m/z) calcd for C32H33IO5P:
655.1110. Found: 655.1116.
2
1JCP ¼ 93.3 Hz, 1CH), 117.88 (q, JCF ¼ 319.6 Hz, CF3), 124.02
1
(d,1JCP ¼ 147.5 Hz, Car), 127.60, 127.83, 127.92, 128.07, 128.25, 128.42,
3
128.48, 128.52, 128.85 (d, JCP ¼ 14.2 Hz, CHar), 133.21 (d,
2JCP ¼ 10.5 Hz, CHar), 134.51 (d, 4JCP ¼ 2.9 Hz, CHar), 136.65 (s, CarBn),
137.54 (s,
C
arBn), 137.87 (s, CarBn). HRMS (m/z) calcd for
5.1.6. (2Sp,3S,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-
C
33H33F3O8PS: 677.1586. Found: 677.1592.
bromo-2-phenyl-2-oxo-2l
5-[1,2]-oxaphosphinane 3b
Under nitrogen, tetraethylammonium bromide (0.032 g,
0.15 mmol) was added to a solution of 5 (0.104 g, 0.15 mmol) in
acetonitrile (3 mL). The reaction mixture was stirred at 80 ꢀC for 3 h,
and solvent was evaporated under vacuum. A normal phase chro-
matography on silica gel using a mixture of n-heptane/ethyl acetate
(60:40) as eluent afforded compound 3b as a colorless oil (0.049 g,
5.1.4. (2Sp,3S,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-
iodo-2-phenyl-2-oxo-2
5-[1,2]-oxaphosphinane 3a
l
Under nitrogen, potassium iodine (0.068 g, 0.41 mmol) was
added to a solution of 5 (0.070 g, 0.10 mmol) in acetonitrile (3 mL).
The reaction mixture was stirred at 80 ꢀC for 2 h, and solvent was
evaporated under vacuum, Ethyl acetate (9 mL) was added to res-
idue and organic solution was washed with water (3 mL). The
organic layer was dried over sodium sulfate, filtered and solvent
was evaporated under vacuum. A normal phase chromatography on
silica gel using a mixture of n-heptane/ethyl acetate (60:40) as
52%). 31P NMR (CDCl3):
d
34.46 (s). 1H NMR (CDCl3):
d
3.72 (dd,
3
2
2JHH ¼ 11.4 Hz, JHH ¼ 1.9 Hz, 1H, OCH2), 3.91 (dt, JHH ¼ 11.4 Hz,
3JHH ¼ 3.0 Hz, JHP ¼ 3.0 Hz, 1H, OCH2), 4.25 (dd, JHH ¼ 9.9 Hz,
4
3
3JHH ¼ 9.0 Hz, 1H, 3CH), 4.37 (ddd, JHH ¼ 9.0 Hz, JHH ¼ 3.3 Hz,
3
3
3JHP ¼ 0.9 Hz, 1H, 2CH), 4.41 (dd, JHP ¼ 6.9 Hz, JHH ¼ 3.3 Hz, 1H,
1CH), 4.52 (d, 2JHH ¼ 12.1 Hz, 1H, OCH2), 4.53 (d, 2JHH ¼ 10.7 Hz, 1H,
OCH2), 4.56 (d, 2JHH ¼ 11.3 Hz, 1H, OCH2), 4.56 (dddd, 3JHH ¼ 9.9 Hz,
2
3
eluent, afforded 3a as a colorless oil (0.042 g, 62%). 31P NMR
3
(CDCl3):
d
35.87 (s). 1H NMR (CDCl3): 3.80 (ddd, JHH ¼ 8.7 Hz,
3JHH ¼ 3.7 Hz, JHP ¼ 2.3 Hz, 1H, 2CH), 3.82 (dd, JHH ¼ 11.4 Hz,
3JHP ¼ 3.2 Hz, JHH ¼ 3.0 Hz, JHH ¼ 1.9 Hz, 1H, 4CH), 4.65 (d,
2JHH ¼ 12.1 Hz, 1H, OCH2), 4.66 (d, 2JHH ¼ 11.3 Hz, 1H, OCH2), 4.85 (d,
2JHH ¼ 10.7 Hz, 1H, OCH2), 7.11e7.14 (m, 2H, CHar), 7.21e7.33 (m,
13H, CHar), 7.41e7.45 (m, 2H, CHar), 7.53e7.58 (m, 1H, CHar),
3
2
3
3
2
3
3JHH ¼ 2.0 Hz, 1H, OCH2), 3.99 (ddd, JHH ¼ 11.4 Hz, JHH ¼ 3.3 Hz,
4JHP ¼ 2.6 Hz, 1H, OCH2), 4.27 (dd, 3JHH ¼ 9.9 Hz, 3JHH ¼ 8.7 Hz, 1H,
3CH), 4.56 (dd, JHP ¼ 8.6 Hz, JHH ¼ 3.7 Hz, 1H, 1H), 4.59 (d,
2
3
2JHH ¼ 11.2 Hz, 1H, OCH2), 4.61 (d, 2JHH ¼ 10.8 Hz, 1H, OCH2), 4.62 (d,
7.84e7.90 (m, 2H, CHar). 13C NMR (CDCl3):
d
43.40 (d, 1JCP ¼ 83.9 Hz,
2JHH ¼ 12.2 Hz, 1H, OCH2), 4.68 (m, JHH ¼ 9.9 Hz, JHH ¼ 3.3 Hz,
1CH), 68.88 (d, JCP ¼ 9.2 Hz, BnOCH2), 71.62 (s, PhCH2), 73.37 (s,
3
3
3
3JHH ¼ 2.0 Hz, 1H, 4CH), 4.73 (d, JHH ¼ 11.2 Hz, 1H, OCH2), 4.76 (d,
PhCH2), 74.54 (d, JCP ¼ 1.7 Hz, 3CH), 75.63 (s, PhCH2), 76.23 (d,
2
3
2JHH ¼ 12.2 Hz, 1H, OCH2), 4.93 (d, JHH ¼ 10.8 Hz, 1H, OCH2),
2JCP
¼
5.8 Hz, 4CH), 78.71 (d, JCP
¼
1.7 Hz, 2CH), 126.24
2
2
7.21e7.23 (m, 2H, CHar), 7.28e7.44 (m, 13H, CHar), 7.50e7.54 (m, 2H,
CHar), 7.61e7.66 (m, 1H, CHar), 7.92e7.97 (m, 2H, CHar). 13C NMR
(d,1JCP ¼ 149.8 Hz, Car), 127.57, 127.71, 127.83, 127.97, 127.99, 128.03,
3
128.22 (d, JCP ¼ 14.0 Hz, CHar), 128.41, 128.45, 128.55, 133.20 (d,
1
3
(CDCl3):
d
22.60 (d, JCP ¼ 80.0 Hz, 1CH), 68.98 (d, JCP ¼ 9.1 Hz,
2JCP ¼ 9.7 Hz, CHar), 133.57 (d, 4JCP ¼ 2.9 Hz, CHar), 137.23 (s, CarBn),
137.91 (s, 1C, CarBn), 138.11 (s, CarBn). HRMS (m/z) calcd for
BnOCH2), 71.34 (s, PhCH2), 73.36 (s, PhCH2), 75.46 (s, PhCH2), 75.99
(d, JCP ¼ 1.1 Hz, 3CH), 76.25 (d, JCP ¼ 5.7 Hz, 4CH), 78.28 (s, 2CH),
C32H33BrO5P: 607.1249. Found: 607.1255.
2
2

R. Babouri et al. / European Journal of Medicinal Chemistry 104 (2015) 33e41
39
5.1.7. (2Sp,3R,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-
bromo-2-phenyl-2-oxo-2
5-[1,2]-oxaphosphinane 4b
35.5%), m.p. 127.1e129.3 ꢀC. 31P NMR (CDCl3):
d
32.37 (s). 1H NMR
2
3
l
(CDCl3):
d
3.79 (dd, JHH ¼ 11.2 Hz, JHH ¼ 2.0 Hz, 1H, OCH2),
Under nitrogen, tetraethylammonium bromide (0.031 g,
0.147 mmol) was added to a solution of 6 (0.100 g, 0.147 mmol) in
acetonitrile (3 mL). The reaction mixture was stirred at 80 ꢀC for 2 h,
and solvent was evaporated under vacuum. A normal phase chro-
matography on silica gel using a mixture of n-heptane/ethyl acetate
(60:40) as eluent afforded compound 4b as a white solid (0.060 g,
3.98e4.03 (m, 1H, OCH2), 4.00 (dd, 1H, 3JHH ¼ 10.9 Hz, 2JHP ¼ 3.1 Hz,
1CH), 4.06 (dd, JHH ¼ 10.2 Hz, JHH ¼ 9.1 Hz, 1H, 3CH), 4.30 (ddd,
3
3
3JHH ¼ 10.9 Hz, JHH ¼ 9.1 Hz, JHP ¼ 2.4 Hz, 1H, 2CH), 4.56 (d,
3
3
2JHH ¼ 12.0 Hz, 1H, OCH2), 4.65 (d, JHH ¼ 12.0 Hz, 1H, OCH2), 4.65
2
(m, 1H, 4CH), 4.70 (d, JHH
¼
10.9 Hz, 1H, OCH2), 4.92 (d,
2
2JHH ¼ 10.3 Hz,1H, OCH2), 4.94 (d, 2JHH ¼ 10.9 Hz,1H, OCH2), 5.02 (d,
2JHH ¼ 10.3 Hz, 1H, OCH2), 7.22e7.24 (m, 2H, CHar), 7.30e7.39 (m,
13H, CHar), 7.54e7.58 (m, 2H, CHar), 7.66e7.70 (m, 1H, CHar),
67%), m.p. 138.5e140.6 ꢀC. 31P NMR (CDCl3):
d
32.42 (s). 1H NMR
2
3
(CDCl3):
d
3.69 (dd, JHH ¼ 11.2 Hz, JHH ¼ 2.0 Hz, 1H, OCH2), 3.84
(dd, 3JHH ¼ 11.2 Hz, 2JHP ¼ 3.1 Hz, 1H, 1CH), 3.90 (dt, 2JHH ¼ 11.2 Hz,
7.90e7.95 (m, 2H, CHar). 13C NMR (CDCl3):
d
55.19 (d, 1JCP ¼ 88.9 Hz,
3JHH ¼ 2.6 Hz, JHP ¼ 2.6 Hz, 1H, OCH2), 3.97 (dd, JHH ¼ 10.0 Hz,
1CH), 68.36 (d, JCP ¼ 9.3 Hz, BnOCH2), 73.49 (s, PhCH2), 75.26 (d,
2JCP ¼ 5.4 Hz, 4CH), 75.64 (s, PhCH2), 77.01 (s, PhCH2), 78.89 (s, 3CH),
83.05 (d, 2JCP ¼ 2.4 Hz, 2CH), 126.25 (d, 1JCP ¼ 144.9 Hz, Car), 127.65,
127.70, 127.83, 127.94, 128.01, 128.08, 128.46, 128.47, 128.51, 128.83
4
3
3
3JHH ¼ 9.2 Hz, 1H, 3CH), 4.23 (ddd, JHH ¼ 11.2 Hz, JHH ¼ 9.2 Hz,
3
3
3JHP ¼ 2.3 Hz, 1H, 2CH), 4.45 (d, 2JHH ¼ 12.0 Hz, 1H, OCH2), 4.54 (d,
2JHH ¼ 12.0 Hz, 1H, OCH2), 4.56 (m, JHH ¼ 10.0 Hz, JHH ¼ 2.6 Hz,
3JHH ¼ 2.0 Hz, 1H, 4CH), 4.61 (d, 2JHH ¼ 10.9 Hz, 1H, OCH2), 4.83 (d,
2JHH ¼ 10.2 Hz,1H, OCH2), 4.83 (d, 2JHH ¼ 10.9 Hz,1H, OCH2), 4.93 (d,
2JHH ¼ 10.2 Hz, 1H, OCH2), 7.12e7.14 (m, 2H, CHar), 7.20e7.30 (m,
13H, CHar), 7.42e7.47 (m, 2H, CHar), 7.54e7.59 (m, 1H, CHar),
3
3
3
2
(d, JCP ¼ 13.9 Hz, CHar), 132.14 (d, JCP ¼ 10.2 Hz, CHar), 133.78 (d,
4JCP ¼ 2.8 Hz, CHar), 137.69 (s, CarBn), 137.70 (s, CarBn), 137.79 (s,
CarBn). HRMS (m/z) calcd for C32H33ClO5P: 563.1754. Found:
563.1755.
7.80e7.85 (m, 2H, CHar). 13C NMR (CDCl3):
d
44.29 (d, 1JCP ¼ 85.4 Hz,
1CH), 68.39 (d, JCP ¼ 9.3 Hz, BnOCH2), 73.50 (s, PhCH2) 75.34 (d,
2JCP ¼ 5.4 Hz, 4CH), 75.60 (s, PhCH2), 76.79 (s, PhCH2), 79.32 (s, 3CH),
82.54 (d, 2JCP ¼ 2.1 Hz, 2CH), 126.36 (d, 1JCP ¼ 146.3 Hz, Car), 127.63,
127.67, 127.82, 127.94, 128.02, 128.07, 128.46, 128.47, 128.51, 128.78
5.1.10. (2Sp,3S,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-
3
fluoro-2-phenyl-2-oxo-2l
5-[1,2]-oxaphosphinane 4d
Under nitrogen, compound 2 (0.82 g, 1.5 mmol) in DCM (6 mL),
was added slowly at ꢁ78 ꢀC to a solution of DAST (1.0 mL, 7.5 mmol)
in DCM (6 mL). The reaction mixture was stirred for 1 h at ꢁ78 ꢀC,
and overnight at 40 ꢀC. At 0 ꢀC, a saturated aqueous solution of
sodium hydrogenocarbonate was added in the reaction mixture.
The aqueous phase was extracted with dichloromethane, and the
organic phase was dried with MgSO4, and evaporated. After two
successive column chromatography using a mixture of n-heptane/
ethyl acetate (60:40) as eluent, compound 4d was obtained as a
3
(d, JCP ¼ 13.9 Hz, CHar), 132.22 (d, 2JCP ¼ 10.2 Hz, CHar), 133.73 (d,
4JCP ¼ 2.9 Hz, CHar), 137.62 (s, CarBn), 137.67 (s, CarBn), 137.81 (s,
C
arBn). HRMS (m/z) calcd for C32H33BrO5P: 607.1249. Found:
607.1246.
5.1.8. (2Sp,3S,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-
chloro-2-phenyl-2-oxo-2l
5-[1,2]-oxaphosphinane 3c
Under nitrogen, tetraethylammonium chloride (0.025 g,
0.15 mmol) was added to a solution of 5 (0.104 g, 0.15 mmol) in
acetonitrile (3 mL). The reaction mixture was stirred at 80 ꢀC for 1 h,
and solvent was evaporated under vacuum. A normal phase chro-
matography on silica gel using a mixture of n-heptane/ethyl acetate
(60:40) as eluent afforded compound 3c as a colorless oil (0.054 g,
white solid (0.022 g, 2.7%), m.p. 93.1e94.5 ꢀC. 31P NMR (CDCl3):
2
d
29.46 (d, JPF ¼ 66.0 Hz). 19F NMR (CDCl3):
d
ꢁ212.54 (d,
2JFP ¼ 66.0 Hz). 1H NMR (CDCl3):
d
3.69 (dd, JHH ¼ 11.2 Hz,
2
3JHH ¼ 2.1 Hz, 1H, OCH2), 3.89 (ddd, JHH ¼ 11.2 Hz, JHP ¼ 2.5 Hz,
3JHH ¼ 2.4 Hz, 1H, OCH2), 3.94 (dd, 3JHH ¼ 9.9 Hz, 3JHH ¼ 9.7 Hz, 1H,
2 4
3CH), 4.35 (dddd, JHF ¼ 11.8 Hz, JHH ¼ 9.7 Hz, JHH ¼ 9.7 Hz,
3
3
3
62%). 31P NMR (CDCl3):
d
34.76 (s). 1H NMR (CDCl3):
d
3.83 (dd,
3JHP ¼ 2.2 Hz, 1H, 2CH), 4.45 (d, JHH ¼ 12.0 Hz, 1H, OCH2), 4.52
2
3
2
2JHH ¼ 11.3 Hz, JHH ¼ 2.0 Hz, 1H, OCH2), 4.01 (ddd, JHH ¼ 11.3 Hz,
(dddd, 3JHH ¼ 9.9 Hz, 3JHP ¼ 4.4 Hz, 3JHH ¼ 2.4 Hz, 3JHH ¼ 2.1 Hz, 1H,
4CH), 4.54 (d, 2JHH ¼ 12.0 Hz, 1H, OCH2), 4.57 (d, 2JHH ¼ 10.8 Hz, 1H,
OCH2), 4.75 (d, 2JHH ¼ 10.8 Hz, 1H, OCH2), 4.78 (ddd, 2JHF ¼ 49.4 Hz,
4
3
3JHH ¼ 3.3 Hz, JHP ¼ 2.7 Hz, 1H, OCH2), 4.37 (dd, JHH ¼ 10.0 Hz,
3JHH ¼ 9.3 Hz, 1H, 3CH), 4.52 (dd, JHP ¼ 6.9 Hz, JHH ¼ 3.2 Hz, 1H,
2
3
1CH), 4.62 (d, 2JHH ¼ 12.6 Hz, 1H, OCH2), 4.64 (d, 2JHH ¼ 10.7 Hz, 1H,
3JHH ¼ 9.7 Hz, JHP ¼ 3.8 Hz, 1H, 1CH), 4.85 (d, JHH ¼ 10.8 Hz, 1H,
2
2
3
3
3
2
OCH2), 4.64 (ddd, JHH ¼ 9.3 Hz, JHH ¼ 3.2 Hz, JHP ¼ 0.7 Hz, 1H,
2CH), 4.65 (m, 1H, 4CH), 4.70 (d, 2JHH ¼ 11.4 Hz, 1H, OCH2), 4.75 (d,
2JHH ¼ 12.6 Hz,1H, OCH2), 4.78 (d, 2JHH ¼ 11.4 Hz,1H, OCH2), 4.97 (d,
2JHH ¼ 10.7 Hz, 1H, OCH2), 7.23e7.25 (m, 2H, CHar), 7.30e7.43 (m,
13H, CHar), 7.52e7.57 (m, 2H, CHar), 7.65e7.69 (m, 1H, CHar),
OCH2), 4.85 (d, JHH ¼ 10.8 Hz, 1H, OCH2), 7.11e7.13 (m, 2H, CHar),
7.19e7.27 (m, 13H, CHar), 7.44e7.49 (m, 2H, CHar), 7.56e7.60 (m, 1H,
CHar), 7.78e7.83 (m, 2H, CHar). 13C NMR (CDCl3):
d 68.31 (d,
3JCP ¼ 9.2 Hz, BnOCH2), 73.48 (s, PhCH2), 74.94 (d, JCP ¼ 5.3 Hz,
2
4CH), 75.73 (s, PhCH2), 76.04 (d, JCP ¼ 2.5 Hz, PhCH2), 77.10 (d,
4
7.95e8.00 (m, 2H, CHar). 13C NMR (CDCl3):
d
52.37 (d, 1JCP ¼ 87.2 Hz,
3JCF ¼ 7.1 Hz, 3CH), 82.15 (dd, JCF ¼ 15.8 Hz, JCP ¼ 4.8 Hz, 2CH),
2
2
3
1
1
1CH), 68.85 (d, JCP ¼ 9.1 Hz, BnOCH2), 71.87 (s, PhCH2), 73.39 (s,
91.35 (dd, JCF
¼
194.1 Hz, JCP
¼
101.7 Hz, 1CH), 126.70
3
PhCH2), 73.74 (d, JCP ¼ 1.8 Hz, 3CH), 75.70 (s, PhCH2), 76.21 (d,
(d,1JCP ¼ 140.1 Hz, Car), 127.65, 127.78, 127.82, 127.88, 127.91, 128.11,
2JCP ¼ 5.8 Hz, 4CH), 79.38 (d, JCP ¼ 2.0 Hz, 2CH), 125.66 (d,
128.42, 128.44, 128.45, 128.91 (d, JCP ¼ 13.7 Hz, CHar), 131.88 (d,
2
3
1JCP ¼ 148.4 Hz, Car), 127.59, 127.73, 127.84, 127.95, 127.98, 128.06,
2JCP ¼ 10.5 Hz, CHar), 133.75 (d, 4JCP ¼ 2.8 Hz, CHar), 137.76 (s, CarBn),
137.77 (s, CarBn), 137.86 (s, CarBn). HRMS (m/z) calcd for C32H33FO5P:
547.2050. Found: 547.2039.
3
128.32 (d, JCP ¼ 13.9 Hz, CHar), 128.42, 128.46, 128.57, 133.24 (d,
2JCP ¼ 9.8 Hz, CHar), 133.65 (d, 4JCP ¼ 2.9 Hz, CHar), 137.27 (s, CarBn),
137.94 (s, CarBn), 137.09 (s, CarBn). HRMS (m/z) calcd for C32H33ClO5P:
563.1754. Found: 563.1755.
5.1.11. (3,4,5-tri-O-benzyl-a-D-arabinofuranosyl) (phenyl)
phosphinic acid 8
5.1.9. (2Sp,3R,4S,5S,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-3-
Under nitrogen, potassium fluoride (0.035 g, 0.6 mmol) was
added to a solution of 5 (0.104 g, 0.15 mmol) in acetonitrile (3 mL).
The reaction mixture was stirred at 80 ꢀC for 5 h, and solvent was
evaporated. An aqueous solution of potassium hydroxide (9 mL,
1.0 M) was added to the residue and the mixture was extracted with
DCM (3 ꢂ 3 mL). The organic layer was dried over sodium sulfate,
filtered and evaporated under vacuum to give compound 8 as a pale
yellow solid (0.070 g, 84%), m.p. 74.5e77.0 ꢀC. 31P NMR (CDCl3):
chloro-2-phenyl-2-oxo-2l
5-[1,2]-oxaphosphinane 4c
Under nitrogen, tetraethylammonium chloride (0.025 g,
0.15 mmol) was added to a solution of 6 (0.088 g, 0.13 mmol) in
acetonitrile (3 mL). The reaction mixture was stirred at 80 ꢀC for 3 h,
and solvent was evaporated under vacuum. A normal phase chro-
matography on silica gel using a mixture of n-heptane/ethyl acetate
(60:40) as eluent afforded compound 4c as a white solid (0.026 g,

40
R. Babouri et al. / European Journal of Medicinal Chemistry 104 (2015) 33e41
d
21.37 (s). 1H NMR (CDCl3):
d
3.13 (dd, 2JHH ¼ 10.0 Hz, 3JHH ¼ 5.4 Hz,
(I > 2s (I)) ¼ 0.0468, wR2 (I > 2s (I)) ¼ 0.1449, R1 (all data) ¼ 0.0574,
wR2 (all data) ¼ 0.1498, S (all data) ¼ 0.916, Dr(min/max) ¼ ꢁ0.45/
0.48 eAꢁ3. Crystal data for 9: Formula ¼ C32H31PO5, T ¼ 175.00(10)
K, Mr ¼ 526.54 g molꢁ1, crystal size ¼ 0.40 ꢂ 0.40 ꢂ 0.40 mm3,
2
3
1H, OCH2), 3.21 (dd, JHH ¼ 10.0 Hz, JHH ¼ 7.4 Hz, 1H, OCH2), 3.61
(dd, JHH ¼ 3.9 Hz, JHH ¼ 2.5 Hz, 1H, 3CH), 3.82 (d, JHH ¼ 11.5 Hz,
3
3
2
2
1H, OCH2), 3.87 (d, JHH
¼
11.5 Hz, 1H, OCH2), 3.90 (dd,
3JHH ¼ 5.6 Hz, JHP ¼ 1.7 Hz, 1H, 1CH), 4.02 (ddd, JHP ¼ 11.5 Hz,
Orthorhombic, space group P212121,
a
¼
10.4652(3) Å,
2
3
3JHH ¼ 5.6 Hz, JHH ¼ 2.5 Hz, 1H, 2CH), 4.10 (m, 1H, 4CH), 4.13 (d,
b ¼ 15.0297(4) Å, c ¼ 18.0287(4) Å,
a
¼ 90ꢀ,
b
¼ 90ꢀ,
g
¼ 90ꢀ,
3
2JHH ¼ 12.4 Hz,1H, OCH2), 4.19 (d, 2JHH ¼ 12.5 Hz, 1H, OCH2), 4.22 (d,
2JHH ¼ 12.5 Hz, 1H, OCH2), 4.24 (d, 2JHH ¼ 12.4 Hz,1H, OCH2), 4.51 (s,
1H, OH), 6.78e6.80 (m, 2H, CHar), 6.99e7.16 (m, 16H, CHar),
V ¼ 2835.72(12) Å3, Z ¼ 4, rc ¼ 1.233 g/cm3,
m
(CuK
a
) ¼ 1.170 mmꢁ1
,
qmax ¼ 61.953, 8167 reflections measured, 4362 unique, 4076 with
I > 2s (I), refined parameters ¼ 343, R1 (I > 2s (I)) ¼ 0.0468, wR2
(I > 2s (I)) ¼ 0.1109, R1 (all data) ¼ 0.0498, wR2 (all data) ¼ 0.1134, S
(all data) ¼ 1.027, Dr(min/max) ¼ ꢁ0.22/0.33 eAꢁ3. Data of 4b
(CCDC 1051163) and 9 (CCDC 1061496) can be obtained free of
charge from the Cambridge Crystallographic Data Centre at www.
ccdc.cam.ac.uk/data_request/cif
7.75e7.79 (m, 2H, CHar). 13C NMR (CDCl3):
d 68.52 (s, BnOCH2), 71.16
(s, PhCH2), 71.63 (s, PhCH2), 72.90 (s, PhCH2), 81.42 (d, 3JCP ¼ 5.0 Hz,
4CH), 82.65 (d, 1JCP ¼ 110.3 Hz, 1CH), 85.06 (d, JCP ¼ 5.1 Hz, 3CH),
3
85.67 (d, JCP ¼ 5.0 Hz, 2CH), 127.29, 127.49, 127.60, 127.62, 127.77,
3
127.95, 128.06, 128.07, 128.30, 128.33, 130.19, 132.50 (d,
JCP ¼ 8.5 Hz), 137.44 (d, 1JCP ¼ 122.5 Hz, Car), 137.63 (s, CarBn), 137.98
(s, CarBn), 138.13 (s, CarBn). HRMS (m/z) calcd for C32H34O6P:
545.2093. Found: 545.2093.
5.3. Pharmacology
5.3.1. Cell lines
5.1.12. (2Rp,5R,6R)-4,5-bis-benzyloxy-6-benzyloxymethyl-2-
MDA-MB-231, MDA-MB-435, B16F10, Caco2, HuH7 and
DU145 cells were obtained from the American Type Culture
Collection. These cell lines were cultured in Dulbecco's modified
Eagle's medium (DMEM) supplemented with 10% fetal calf serum
(FCS), 2 mM
streptomycin.
phenyl-2-oxo-2l
5-[1,2]oxa phosphine-3-ene 9
Under nitrogen, cesium fluoride (0.245 g, 1.61 mmol) was added
to a solution of 3a (0.264 g, 0.40 mmol) in DMSO (8 mL). The re-
action mixture was stirred at 95 ꢀC for 75 min. The solvent was
evaporated and dichloromethane was added. The organic layer was
washed with water, dried over sodium sulfate and concentrated
under vacuum. The residue was purified by column chromatog-
raphy on silica gel with n-heptane/ethyl acetate (30/70) to give
product 9 (0.170 g, 80%). m.p. 95.8e96.6 ꢀC. 31P NMR (CDCl3):
L
-glutamine, 1 mM sodium pyruvate, 50 U mLꢁ1
5.3.2. Cell viability experiment. The compounds are solubilized in
100% DMSO and tested at 1% DMSO for the first concentration
Cell viability was evaluated using the MTT microculture tetra-
zolium assay [30]. Cells were seeded at a density of 5 ꢂ 104 cells/
well in 96-well flat-bottom plates (Falcon, Strasbourg, France) and
incubated in complete culture medium for 24 h. Then, medium was
removed and replaced by 2% FCS (Fetal Calf Serum)-medium con-
d
27.96 (s). 1H NMR (CDCl3):
d
3.72 (dd, 2JHH ¼ 11.2 Hz, 3JHH ¼ 2.1 Hz,
1H, OCH2), 3.87 (dt, 2JHH ¼ 11.2 Hz, 3JHH ¼ 2.5 Hz, 4JHP ¼ 2.5 Hz, 1H,
OCH2), 4.41 (d, 2JHH ¼ 12.0 Hz,1H, OCH2), 4.47 (d, 2JHH ¼ 10.4 Hz,1H,
OCH2), 4.54 (d, 2JHH ¼ 12.0 Hz, 1H, OCH2), 4.58 (ddd, 3JHH ¼ 9.6 Hz,
4JHP ¼ 2.0 Hz, JHH ¼ 1.2 Hz, 1H, 3CH), 4.66 (dddd, JHH ¼ 9.6 Hz,
taining increasing concentrations of a-halogenated oxaphosphi-
4
3
3JHP ¼ 4.9 Hz, JHH ¼ 2.5 Hz, JHH ¼ 2.1 Hz, 1H, 4CH), 4.74 (d,
2JHH ¼ 11.3 Hz, 1H, OCH2), 4.79 (d, 2JHH ¼ 10.4 Hz, 1H, OCH2), 4.86 (d,
2JHH ¼ 11.3 Hz, 1H, OCH2), 4.90 (dd, 2JHP ¼ 12.2 Hz, 4JHH ¼ 1.2 Hz, 1H,
1CH), 7.05e7.09 (m, 2H, CHar), 7.14e7.30 (m, 13H, CHar), 7.35e7.39
nanes. After 72 h incubation, cells were washed with phosphate
buffered saline h72 h (PBS, Life Technologies) and incubated with
0.1 mL of MTT (2 mg/mL, SigmaeAldrich) for additional 4 h at 37 ꢀC.
The insoluble product was then dissolved by addition of DMSO
(SigmaeAldrich). Optical density was measured at 570 nm using a
Labsystems Multiskan MS microplate reader. Experiments were
performed in triplicate.
3
3
(m, 2H, CHar), 7.45e7.49 (m, 1H, CHar), 7.72e7.77 (m, 2H, CHar). 13
C
3
NMR (CDCl3):
d
68.70 (d, JCP ¼ 8.6 Hz, BnOCH2), 70.43 (d,
4JCP ¼ 1.6 Hz, PhCH2), 72.25 (d, 3JCP ¼ 4.1 Hz, 3CH), 73.56 (s, PhCH2),
2
74.64 (d, JCP
¼
6.4 Hz, 4CH), 75.44 (s, PhCH2), 87.58 (d,
1JCP ¼ 133.5 Hz, 1CH), 127.74, 127.78, 127.93, 127.99, 128.33, 128.36,
5.3.3. Measurements of a-halogenated oxaphosphinanes effects on
cancer cell line cultures (B16, MDAMB435), migration and invasion
3
128.40, 128.53 (d, JCP
¼
6.5 Hz, CHar), 128.72, 131.84 (d,
2JCP ¼ 10.7 Hz, CHar), 131.86 (d,1JCP ¼ 152.3 Hz, Car), 132.39 (d,
4JCP ¼ 2.8 Hz, CHar), 134.95 (s, CarBn), 137.42 (s, CarBn), 137.97 (s,
For migration inserts of Boyden chambers were coated over-
night with 20
(human plasma, BD Biosciences) washed in PBS and blocked with
0.5% BSA for 1 h. For invasion 100 L of matrigel (BD Matrigel TM
mg/mL of either laminin), fibronectin or vitronectin
C
arBn), 169.18 (d, 2JCP ¼ 11.8 Hz, 2C). HRMS (m/z) calcd for C32H32O5P:
527.1987. Found: 527.1986.
m
Matrix, mouse EHS tumor, LDEV; BD Biosciences) diluted 33 times
in PBS was added in the insert. Cells (50 ꢂ 105) resuspended in
DMEM supplemented with 0.1% BSA were plated into the upper
compartment and incubated for 24 h with and without treatment.
The upper side of the filter was wiped off to remove non-migrating
cells, and cells attached to the lower side were fixed for 10 min with
methanol, stained with crystal violet and fully counted using a Zeiss
axiophot microscope (x200). The % of migration inhibition (% Inh)
was calculated as follows: % Inh ¼ 100 ꢁ (number of cell migrating
without treatment/number of cell migrating under treatment) x
100. Experiments were performed in triplicate.
5.2. X-ray experiments
Using Olex2 [28], the crystals structures were solved with the
ShelXT [29] structure solution program using Direct Methods and
refined with the ShelXL [26] refinement package using Least
Squares minimization. Refinement of the absolute structure Flack
parameters [27], while the Hooft analysis [28] gave absolutes
parameters ꢁ0.001(17) for 4b and ꢁ0.020(18) for 9 which confi-
dently confirms that the refined coordinates represent the true
enantiomorph.
Crystal data for 4b: Formula ¼ 0.5(C32H32BrO5P), C32H33BrO5P
T
¼
175.00(14) K, Mr
¼
607.45
g
molꢁ1
,
crystal
5.3.4. Statistical analyses
size ¼ 0.30 ꢂ 0.40 ꢂ 0.35 mm3, Monoclinic, space group P21,
The presented experiments were carried out at least in tripli-
cate. Depending on the number of independent variables Student's
or ANOVA statistical tests was applied, using serf software (bra-
m.org/serf/CellsAndMaps.php). EC50 values and Ki were calculated
using the Hill equation of the doseelog response curves.
a ¼ 5.61523(10) Å, b ¼ 23.1126(3) Å, c ¼ 22.1330(3) Å,
a
¼ 90ꢀ,
b
¼ 91.4033(15)ꢀ,
g
¼ 90ꢀ, V ¼ 2871.62(8) Å3, Z ¼ 4, rc ¼ 1.405 g/cm3,
m
(CuK
a
) ¼ 2.800 mmꢁ1
qmax ¼ 67.613, 24,229 reflections measured,
,
10,273 unique, 9002 with I > 2s (I), refined parameters ¼ 703, R1

R. Babouri et al. / European Journal of Medicinal Chemistry 104 (2015) 33e41
41
[16] X. Li, S. Zhang, P. Zhao, Z. Kovacs, A.D. Sherry, Synthesis and NMR studies of
new DOTP-like lanthanide (III) complexes containing a hydrophobic substit-
uent on one phosphonate side arm, Inorg. Chem. 40 (2001) 6572e6579.
[17] G.T. Giuffredi, L.E. Jennings, B. Bernet, V. Gouverneur, Facile synthesis of 4-
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2015.09.027.
deoxy-4-fluoro-
a
-d-talopyranoside,
4-deoxy-4-fluoro-
a-d-idopyranoside
and 2, 4-dideoxy-2, 4-difluoro-
772e778.
a-d-talopyranoside, J. Fluor. Chem. 132 (2011)
References
[18] X. Creary, T.L. Underiner, Stabilization demands of diethyl phosphonate
substituted carbocations as revealed by substituent effects, J. Org. Chem. 50
(1985) 2165e2170.
[1] J.A. Schwartzbaum, J.L. Fisher, K.D. Aldape, M. Wrensch, Epidemiology and
molecular pathology of Glioma, Nat. Clin. Pract. Neurol. 2 (2006) 494e503.
[19] Y. Xu, M.T. Flavin, Z.-Q. Xu, Preparation of new wittig reagents and their
ꢀ
[2] L. Bauchet, H. Mathieu-Daude, P. Fabbro-Peray, V. Rigau, M. Fabbro, O. Chinot,
application to the synthesis of a, b-unsaturated phosphonates, J. Org. Chem.
61 (1996) 7697e7701.
ꢀ
L. Pallusseau, C. Carnin, K. Laine, A. Schlama, A. Thiebaut, M.C. Patru,
F. Bauchet, M. Lionnet, M. Wager, T. Faillot, L. Taillandier, D. Figarella-Branger,
L. Capelle, H. Loiseau, D. Frappaz, C. Campello, C. Kerr, H. Duffau, M. Reme-
Saumon, B. Tretarre, J.-P. Daures, D. Henin, F. Labrousse, P. Menei, J. Honnorat,
[20] T.-H. Lin, P. Kovac, C.-P.-J. Glaudemains, Improved synthesis of the 2-, 3-, and
4-deoxy derivatives from methyl b-d-galactopyranoside, Carbohydr. Res. 188
(1989) 228e238.
ꢀ
Oncological patterns of care and outcome for 952 patients with newly diag-
nosed glioblastoma in 2004, Neuro Oncology 12 (2010) 725e735.
[3] L. Clarion, C. Jacquard, O. Sainte-Catherine, S. Loiseau, D. Filippini, M.-
H. Hirlemann, J.-N. Volle, D. Virieux, M. Lecouvey, J.-L. Pirat, N. Bakalara,
Oxaphosphinanes: new therapeutic perspectives for glioblastoma, J. Med.
Chem. 55 (2012) 2196e2211.
[4] L. Clarion, C. Jacquard, O. Sainte-Catherine, M. Decoux, S. Loiseau, M. Rolland,
M. Lecouvey, J.-P. Hugnot, J.-N. Volle, J.-L. Pirat, N. Bakalara, C-glycoside mi-
metics inhibit glioma stem cell proliferation, migration, and invasion, J. Med.
Chem. 57 (2014) 8293e8306.
[5] G.W. Gribble, The diversity of natural organochlorines in living organisms,
Pure Appl. Chem. 68 (1996) 1699e1712.
[6] G.W. Gribble, Recently discovered naturally occurring heterocyclic organo-
halogen compounds, Heterocycles 84 (2012) 157e207.
[7] B.-G. Wang, J.B. Gloer, N.-Y. Ji, J.-C. Zhao, halogenated organic molecules of
rhodomelaceae origin, Chem. Biol. Rev. 113 (2013) 3632e3685.
[8] G.W. Gribble, The diversity of naturally occurring organobromine compounds,
Chem. Soc. Rev. 28 (1999) 335e346.
[9] L. Wang, X. Zhou, M. Fredimoses, S. Liao, Y. Liu, Naturally occurring organo-
iodines, RSC Adv. 4 (2014) 57350e57376.
[21] J.-W. Wilt, M. Peeran, A reactive intermediate formed by triflate rearrange-
ment. A new displacement reaction for carbohydrate synthesis,, J. Org. Chem.
51 (1986) 2619e2621.
[22] E.P.A. Couzijn, J.C. Slootweg, A.W. Ehlers, K. Lammertsma, Stereomutation of
pentavalent compounds: validating the berry pseudorotation, redressing Ugi's
turnstile rotation, and revealing the two- and three-arm turnstiles, J. Am.
Chem. Soc. 132 (2010) 18127e18140.
[23] D. Crich, L. Li, 4,6-O-benzylidene-directed
b-mannopyranosylation and a-
glucopyranosylation: the 2-deoxy-2-fluoro and 3-deoxy-3-fluoro series of
donors and the importance of the O2ꢁC2ꢁC3ꢁO3 interaction, J. Org. Chem. 72
(2007) 1681e1690.
[24] CrysAlisPro, Version 1.171.35.21, Agilent Technologies, Yarnton, Oxfordshire,
England, 2012.
[25] G.M. Sheldrick, A short history of SHELX, Acta Crystallogr. Sect. A 64 (2008)
112e122.
[26] (a) H.D. Flack, G. Bernardinelli, Absolute structure and absolute configuration,
Acta Crystallogr. Sect. A 55 (1999) 908e915;
(b) H.D. Flack, G. Bernardinelli, Reporting and evaluating absolute-structure
and absolute-configuration determinations, J. Appl. Crystallogr. 33 (2000)
1143e1148.
[10] G.W. Gribble, Naturally occurring organofluorines, the handbook of environ-
mental chemistry, Ed, vol. 3, Springer-Verlag, 2002, pp. 121e136.
[11] K.K.J. Chan, D. O'Hagan, The rare fluorinated natural products and biotech-
nological prospects for fluorine enzymology methods in enzymology, Ed.
Elsevier 516 (2012) 219e235.
[12] B.R. Smith, C.M. Eastman, J.T. Njardarson, Beyond C, H, O, and N!, analysis of
the elemental composition of U.S. FDA approved drug architectures, J. Med.
Chem. 57 (2014) 9764e9773.
[13] P. Shah, A.D. Westwell, Organofluorine compounds in biology and medicine,
J. Enzyme Inh. Med. Chem. 22 (2007) 527e540.
[14] S. Purser, P.R. Moore, S. Swallow, V. Gouverneur, Fluorine in medicinal
chemistry, Chem. Soc. Rev. 37 (2008) 320e330.
[27] (a) R.W. Hooft, L.H. Straver, A.L. Spek, Determination of absolute structure
using Bayesian statistics on Bijvoet differences, J. Appl. Crystallogr. 41 (2008)
96e103;
(b) R.W. Hooft, L.H. Straver, A.L. Spek, Using the t-distribution to improve the
absolute structure assignment with likelihood calculations, J. Appl. Crys-
tallogr. 43 (2010) 665e668.
[28] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann, OLEX2:
a complete structure solution, refinement and analysis program, J. Appl.
Crystallogr. 42 (2009) 339e341.
[29] G.M. Sheldrick, Crystal structure refinement with SHELXL, Acta Crystallogr.
Sect. A 71 (2015) 3e8.
[30] T. Mosmann, Rapid colorimetric assay for cellular growth and survival:
application to proliferation and cytotoxicity assays, J. Immunol. Methods 65
(1983) 55e63.
[15] D. Filippini, S. Loiseau, N. Bakalara, Z.A. Dziuganowska, A. Van der Lee, J.-
N. Volle, D. Virieux, J.-L. Pirat, Dramatic effect of modified boranes in dia-
stereoselective reduction of chiral cyclic
a-ketophosphinates, RSC Adv. 2
(2012) 816e818.