Synthesis of (1R,2R)- and (1S,2R)-1,2-epoxy-3-hydroxypropylphosphonates as analogues of fosfomycin

Article abstract of DOI:10.1002/ardp.200900044

Cyclohexylammonium (1R,2R)-1,2-epoxy-3-hydroxypropylphosphonate was conveniently synthesized from dibenzyl (1S,2R)-2,3-O-cyclohexylidene-1,2,3- trihydroxypropylphosphonate by a reaction sequence including mesylation, hydrolysis of acetal, intramolecular W

Full text of DOI:10.1002/ardp.200900044

Arch. Pharm. Chem. Life Sci. 2009, 342, 521–527
A. E. Wrꢀblewski et al.
521
Full Paper
Synthesis of (1R,2R)- and (1S,2R)-1,2-Epoxy-3-
hydroxypropylphosphonates as Analogues of Fosfomycin
1
2
1
´
Andrzej E. Wrꢀblewski , Eligia M. Szewczyk , and Irena I. Ba˛k-Sypien
1
Bioorganic Chemistry Laboratory, Faculty of Pharmacy, Medical University of Lꢀdz, Lꢀdz, Poland
Pharmaceutical Microbiology Laboratory, Faculty of Pharmacy, Medical University of Lꢀdz, Lꢀdz, Poland
2
Cyclohexylammonium (1R,2R)-1,2-epoxy-3-hydroxypropylphosphonate was conveniently synthe-
sized from dibenzyl (1S,2R)-2,3-O-cyclohexylidene-1,2,3-trihydroxypropylphosphonate by a reac-
tion sequence including mesylation, hydrolysis of acetal, intramolecular Williamson reaction,
and hydrogenation in the presence of cyclohexylamine. For dibenzyl (1S,2R)-2,3-O-cyclohexyli-
dene-1,2,3-trihydroxypropylphosphonates the same approach was not successful, since prior the
epoxide-ring closure tritylation of HO–C3 in dibenzyl (1R,2R)-2,3-dihydroxy-1-mesyloxypropyl-
phosphonate was necessary and the hydrogenolysis of dibenzyl (1S,2R)-1,2-epoxy-3-trityloxypro-
pylphosphonate yielded a complex reaction mixture.
Keywords: Antibacterial / Epoxides / Fosfomycin / Synthesis /
Received: March 4, 2009; accepted: April 29, 2009
DOI 10.1002/ardp.200900044
Introduction
A vast number of natural compounds possessing an oxir-
ane ring displays antifungal, antibacterial [1–7], and
Figure 1. Structure of (1R,2S)-1 (Fosfomycin).
anticancer activity [8–16] and also acts as enzyme inhibi-
tors [17–23]. Fosfomycin ((1R,2S)-1,2-epoxypropylphos-
phonic acid 1; Fig. 1) which was isolated in 1969 from
strains of Streptomyces fradiae is among the best recog-
nized natural epoxides pharmacologically useful in treat-
ment of urinary tract infections caused by Gram-negative
and Gram-positive bacteria [24, 25]. According to the gen-
erally accepted mode of action, fosfomycin inhibits the
biosynthesis of the bacterial cell wall by inactivation of
pyruvyl transferase [26].
We anticipated that replacement of the methyl group
in fosfomycin for the hydroxymethyl group would signif-
icantly increase the polarity of the analogue and could
introduce additional, hopefully binding, interactions
within the enzyme active site. Synthesis of all enantiom-
ers of diethyl 1,2-epoxy-3-hydroxypropylphosphonates
has already been described [27, 28]. Since hydrolytic
cleavage of phosphonate esters would destroy the epox-
ide ring, another approach was necessary and we decided
to study the feasibility of the benzyl esters hoping to
cleanly remove benzyl groups in the presence of the oxir-
ane ring by the catalytic hydrogenolysis. The synthetic
strategy is outlined in Scheme 1 and follows the method-
ology described earlier [27] except for the preparation of
the starting materials and final products.
Results and discussion
The triethylamine-catalyzed addition of dibenzyl phos-
phite to 2,3-O-cyclohexylidene-D-glyceraldehyde led to a
0.95 : 1 mixture of dibenzyl (1R,2R)- and (1S,2R)-2,3-O-
cyclohexylidene-1,2,3-trihydroxypropylphosphonates
in almost quantitative yield. Diastereoisomeric phospho-
Correspondence: Andrzej. E. Wrꢀblewski, Bioorganic Chemistry Labo-
ratory, Faculty of Pharmacy, Medical University of Lꢀdz, 90-151 Lꢀdz,
Muszynskiego 1, Poland.
3
E-mail: andrzej.wroblewski@umed.lodz.pl
nates 3 were separated chromatographically on silica gel
Fax: +48 42 678-8398
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A. E. Wrꢀblewski et al.
Arch. Pharm. Chem. Life Sci. 2009, 342, 521–527
Figure 2. Structure of compound (2S/R,3S,4R)-9.
Scheme 1. Retrosynthesis of enantiomers of 1,2-epoxy-3-
hydroxypropylphosphonate.
diethyl ether / hexane mixture. Removal of the cyclohex-
ylidene groups from (1R,2R)- and (1S,2R)-4 was accom-
plished with aqueous trifluoroacetic acid without forma-
tion of any side products to give after two hours the diols
(1R,2R)- and (1S,2R)-5, in 73 and 70% yield, respectively
(Schemes 3 and 4) [30]. When hydrochloric acid was used
to hydrolyse the acetals [27], the expected diols 5 were
produced in low yield. Furthermore, formation of several
unidentified phosphonates was observed by 31P-NMR
spectroscopy when the reaction time was extended.
According to our earlier experience, the primary
hydroxyl group had to be selectively protected by the tri-
tyl group [27] before the epoxide ring closure in phospho-
nate (1R,2R)-5. The respective 3-O-trityl derivative (1R,2R)-
6 was obtained in 60% yield only, because under the basic
conditions employed in the tritylation the formation of
by-products was noticed. Among them, based on the anal-
yses of the31P-NMR spectra of the crude reaction mixture,
P-epimeric 3,4-epoxy-1,2-oxaphospholanes 9 (d 31P: 31.09
and 29.95 ppm) were identified [27].
Reagents and conditions: a) (BnO)2P(O)H, Et3N, r.t., 24 h, 98%.
Scheme 2. Synthesis of dibenzyl (1R,2R)- and (1S,2R)-2,3-O-
cyclohexylidene-1,2,3-trihydroxypropylphosphonates 3.
to give (1R,2R)-3 (d 31P: 22.23 ppm) and (1S,2R)-3 (d 31P:
22.62 ppm) in 20 and 52% yield, respectively (Scheme 2).
The absolute configurations at C-1 in (1R,2R)- and (1S,2R)-
3 were established by comparison of their 1H and 31P spec-
tral data with those of the corresponding ethyl esters
[29].
Mesylation of the HO–C-1 groups in the enantiomeri-
cally pure phosphonates (1R,2R)- and (1S,2R)-3 was per-
formed under standard conditions [27]. Pure 1-O-mesyl
derivatives (1R,2R)- and (1S,2R)-4 were obtained after chro-
matographic purification and crystallization from a
When the 3-O-trityl phosphonate (1R,2R)-6 was treated
with potassium carbonate suspended in THF at room
Reagents and conditions: a) MsCl, Et3N, DMAP, 08C to r.t., 5 h, 83%; b) 70% CF3COOH, r.t., 2 h, 73%; c) TrCl, Et3N, DMAP,
08C to r.t., 20 h, 60%; d) K2CO3, THF, r.t., 20 h, 73%; e) H2, Pd / C, C6H11NH2, r.t., THF, 24 h.
Scheme 3. Synthesis of compound (1S,2R)-2.
Reagents and conditions: a) MsCl, Et3N, DMAP, 08C to r.t., 5 h, 79%; b) 70% CF3COOH, r.t., 2 h, 70%; c) K2CO3, THF, r.t.,
24 h, 70%; d) H2, Pd / C, C6H11NH2, r.t., THF, 24 h, 92%.
Scheme 4. Synthesis of compound (1R,2R)-2.
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Arch. Pharm. Chem. Life Sci. 2009, 342, 521–527
Synthesis of 1,2-Epoxy-3-hydroxypropylphosphonates
523
Table 1. Minimum inhibitory concentration (MIC in lg/mL) values of compounds, which presented any antibacterial activity.
Compound
S. aureus strains:
ATCC 25923
B. subtilis
ATCC 6633
E. faecalis
ATCC 29212
E. coli strains:
ATCC 8739
P. aeruginosa
ATCC 27853
ATCC 6538P
ATCC 35218
ATCC 25922
(1R,2S)-10
(1S,2S)-10
(1R,2S)-11
(1S,2S)-11
Reference compound
(fosfomycin)
N
N
N
N
500
125
N
N
N
N
N
N
N
N
N
N
N
N
N
N
15.2
62.5
31.2
500
500
500
500
31.25
N – growth not inhibited.
Figure 3. Epoxyphosphonates tested for antibacterial activity.
temperature for 20 h to execute the epoxide ring closure
The cyclohexylammonium salt (1R,2R)-2 and several
by the intramolecular Williamson reaction, the epoxy- previously synthesized, structurally related epoxyhy-
phosphonate (1S,2R)-7 was obtained as a single product droxypropylphosphonates (Fig. 1) were tested to find
in 73% yield (Scheme 3). On the other hand, the transfor- their presumable antibacterial activity against Gram-neg-
mation of the 1-O-mesyl phosphonate (1S,2R)-5 into the ative (Escherichia coli, Pseudomonas aeruginosa) and Gram-
epoxyphosphonate (1R,2R)-8 was accomplished in the positive (Staphylococcus aureus, Enterococcus faecalis, Bacil-
usual manner (potassium carbonate suspended in THF) lus subtilis) bacteria. Minimum inhibitory concentration
without involvement of protective groups (Scheme 4). To (MIC) values of all compounds were estimated in a
avoid the formation of any transesterification products, decreasing concentrations mode starting from 500 lg/
tetrahydrofuran was applied as a solvent instead of low- mL. Weak activity (MIC = 500 lg/mL) against Pseudomonas
boiling alcohols.
aeruginosa ATCC 27853 was detected for (1R,2S)- and
Several attempts to hydrogenolytically remove the tri- (1S,2S)-1,2-epoxy-3-hydroxypropylphosphonates 10 and
tyl and benzyl protective groups from phosphonates (1R,2S)- and (1S,2S)-1-benzyloxy-2,3-epoxypropylphospho-
(1S,2R)-7 and (1R,2R)-8 failed to give the epoxides (1S,2R)- nates 11, while the reference fosfomycin sodium salt
and (1R,2R)-2 in satisfactory yield and purity. Following a inhibited growth of this strain in a much lower concen-
literature report [31], the epoxyphosphonate (1R,2R)-8 tration (Table 1).
was subjected to catalytic hydrogenolysis in the presence
of cyclohexylamine in THF to provide pure (1R,2R)-2 as a
cyclohexylammonium salt in 92% yield (Scheme 4). How-
ever, under the same conditions the pure cyclohexylam-
Conclusions
monium salt (1S,2R)-2 could not be isolated from the 3-O- Enantiomerically pure dibenzyl (1R,2R)- and (1S,2R)-2,3-O-
trityl epoxyphosphonate (1S,2R)-7 (Scheme 3).
cyclohexylidene-1,2,3-trihydroxypropylphosphonates
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Arch. Pharm. Chem. Life Sci. 2009, 342, 521–527
were obtained from 2,3-O-cyclohexylidene-D-glyceralde- General procedure for the preparation of the starting
hyde and dibenzyl phosphite. After mesylation and ace- materials 3
A mixture of 2,3-O-cyclohexylidene-D-glyceraldehyde (5.00 g,
tal cleavage dibenzyl (1R,2R)- and (1S,2R)-2,3-dihydroxy-1-
29.4 mmol), dibenzyl phosphite (3.59 mL, 27.9 mmol) and tri-
mesyloxypropylphosphonates were cleanly prepared to
ethylamine (0.374 mL, 2.94 mmol) was left at room temperature
study the intramolecular Williamson reaction. Dibenzyl
for 24 h. After removal of all volatiles in vacuo, the residue was
(1R,2R)-1,2-epoxy-3-hydroxypropylphosphonate
(the
chromatographed on a silica gel column with chloroform /
methanol (100 : 1, v / v) to give (1R,2R)-3 (2.081 g, 23%) and
(1S,2R)-3 (4.80 g, 53%) both as fluffy white needles after crystalli-
zation from hexane.
trans-configured isomer) was obtained directly from
dibenzyl (1S,2R)-2,3-dihydroxy-1-mesyloxypropylphosph-
onate. However, for the synthesis of dibenzyl (1S,2R)-1,2-
epoxy-3-hydroxypropylphosphonate (isomer cis) trityla-
tion of the primary hydroxy group in dibenzyl (1R,2R)-
2,3-dihydroxy-1-mesyloxypropylphosphonate was neces-
sary because under basic conditions intramolecular
transesterification followed by hydrolysis of the already
formed 1,2-oxaphospholane ring led to complex reaction
mixtures. Catalytic hydrogenolysis of dibenzyl (1R,2R)-
1,2-epoxy-3-hydroxypropylphosphonate was successfully
accomplished in the presence of cyclohexylamine to only
give the respective cyclohexylammonium salt. Several
1,2-epoxy-3-hydroxypropylphosphonates (Table 1) exhib-
ited negligible activity against Pseudomonas aeruginosa
ATCC 27853, while cyclohexylammonium (1R,2R)-1,2-
epoxy-3-hydroxypropylphosphonate was found inactive
against this strain.
Dibenzyl (1R,2R)-2,3-O-cyclohexylidene-1,2,3-
trihydroxypropylphosphonate 3
20
M.p.: 65.5–688C; ½aꢀD = –3.5 (c = 1.2, CHCl3); IR (KBr) m [cm– 1]:
3303, 2934, 2859, 1251, 1103, 1037, 1009, 738, 697; 1H-NMR
(300 MHz, CDCl3) d [ppm]: 1.61–1.37 (m, 10H, Hcyclohex), 3.0–1.8
(brs, 1H, OH), 3.86 (dd, J = 9.9 Hz, J = 4.5 Hz, 1H, H-1), 3.90 (dd, J =
8.7 Hz, J = 6.6 Hz, 1H, H-3a), 4.03 (dd, J = 8.7 Hz, J = 6.6 Hz, 1H, H-
3b), 4.48 (ddt, J = 6.6 Hz, J = 6.6 Hz, J = 4.5 Hz, J = 3.9 Hz, 1H, H-2),
5.10 (dd, JAB = 7.5 Hz, 4H, H2COP), 7.38–7.31 (m, 10H, Ar-H); 13C-
NMR (75.5 MHz, CDCl3) d [ppm]: 24.0, 24.1, 24.2, 35.3, 36.3, 65.9
(d, J = 9.8 Hz, C-3), 68.3 and 68.6 (2d, J = 6.8 Hz, CH2OP), 68.6 (d, J =
160.7 Hz, C-1), 74.4 (d, J = 3.8 Hz, C-2), 110.7, 127.0, 128.0, 128.1,
128.5, 128.6, 128.7, 136.0 and 136.2 (2d, J = 6.0 Hz, Cipso); 31P-NMR
(121.5 MHz, CDCl3) d [ppm]: 22.24. Anal. calcd. for C23H29O6P: C,
63.88; H, 6.76. Found: C, 63.82; H, 6.74.
Dibenzyl (1S,2R)-2,3-O-cyclohexylidene-1,2,3-
trihydroxypropylphosphonate 3
20
The authors wish to express their gratitude to Mrs. Edyta Grze-
lewska for her involvement in this project. This work was sup-
ported by the Medical University of Lꢀdz internal grants (502-
13-331, 503-3014-1 and 503-3012-3).
M.p.: 88.5–908C; ½aꢀD = + 4.6 (c = 2.3, CHCl3); IR (KBr) m [cm– 1]:
3248, 2933, 2890, 1455, 1224, 1097, 1052, 997, 742, 696; 1H-NMR
(300 MHz, CDCl3) d [ppm]: 1.62–1.58 (m, 10Hcyclohex), 2.69 (brs, 1H,
OH), 4.00 (dd, J = 8.7 Hz, J = 6.6 Hz, 1H, H-3a), 4.08 (dd, J = 8.7 Hz, J
= 6.3 Hz, 1H, H-3b), 4.17 (dd, J = 8.4 Hz, J = 4.2 Hz, 1H, H-1), 4.37
(ddt, J = 6.6 Hz, J = 6.3 Hz, J = 4.2 Hz, J = 3.0 Hz, 1H, H-2), 5.08 (dd, J
= 8.4 Hz, 4H, H2COP), 7.39–7.29 (m, 10H, Ar-H); 13C-NMR
(75.5 MHz, CDCl3) d [ppm]: 24.0, 24.2, 25.4, 35.0, 36.2, 65.2 (d, J =
5.7 Hz, C-3), 68.4 and 68.5 (2d, J = 6.8 Hz, CH2OP), 68.5 (d, J =
161.2 Hz, C-1), 74.8 (d, J = 7.2 Hz, C-2), 110.0, 128.1, 128.1, 128.1,
128.6, 128.7, 128.7, 136.0 and 136.1 (2d, J = 6.0 Hz, Cipso); 31P-NMR
(121.5 MHz, CDCl3) d [ppm]: 23.33. Anal. calcd. for C23H29O6P: C,
63.88; H, 6.76. Found: C, 63.69; H, 7.10.
The authors have declared no conflict of interest.
Experimental
General procedure for the preparation of the mesylate 4
Solutions of phosphonates in CH2Cl2 containing NEt3 (three
equiv.) were cooled to 08C and mesyl chloride (two equiv.) was
added dropwise. After 5 h at room temperature, the reaction
mixtures were washed with water (3625 mL), the organic
phases were dried over MgSO4, concentrated, and the crude
products were chromatographed on a silica gel column with
chloroform / methanol (100 : 1).
Chemistry
Melting points were determined on a Boetius apparatus and are
uncorrected. Polarimetric measurements were conducted on a
Perkin Elmer 241 MC apparatus (Perkin Elmer Beaconsfield, UK).
IR spectral data were measured on an Infinity MI-60 FT-IR spec-
trometer (Mattson, Madison, WI, USA). 1H-NMR spectra were
recorded with a Varian Mercury-300 spectrometer (Varian Inc.,
Palo Alto, CA, USA) and Bruker DPX-250 (Bruker Bioscience,
USA); chemical shifts d in ppm with respect to TMS; coupling
constants J in Hz. 13C- and 31P-NMR spectra were recorded on a
Varian Mercury-300 machine at 75.5 and 121.5 MHz and Bruker
DPX-250 machine at 62.9 and 101.5 MHz, respectively. Elemental
analyses were performed by the Microanalytical Laboratory of
this Faculty on a Perkin Elmer PE 2400 CHNS analyzer. The fol-
lowing absorbents were used: column chromatography, Merck
silica gel 60 (70–230 mesh); analytical TLC, Merck TLC plastic
sheets silica gel 60 F254 (Merck, Germany).
Dibenzyl (1R,2R)-2,3-O-cyclohexylidene-1-mesyloxy-
2,3-dihydroxypropylphosphonate 4
According to the general procedure, the reaction of phospho-
nate (1R,2R)-3 (2.18 g, 5.04 mmol) with mesyl chloride (0.79 mL,
10.1 mmol) in the presence of NEt3 (2.29 mL, 15.1 mmol) in
CH2Cl2 (40 mL) afforded the mesylate (1R,2R)-4 (2.14 g, 83%) as a
white needles after crystallization from diethyl ether / hexane;
20
M.p.: 79–808C; ½aꢀD = –8.7 (c = 1.3, CHCl3); IR (KBr) m [cm– 1]: 700,
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Arch. Pharm. Chem. Life Sci. 2009, 342, 521–527
Synthesis of 1,2-Epoxy-3-hydroxypropylphosphonates
525
747, 1012, 1181, 1256, 1366, 2853, 2993, 2933; 1H-NMR
(300 MHz, CDCl3) d [ppm]: 1.65–1.38 (m, 10Hcyclohex), 3.13 (s, 3H,
CH3SO2), 3.96 (dd, J = 9.3 Hz, J = 6.6 Hz, 1H, H-3a), 4.06 (dd, J =
9.3 Hz, J = 6.0 Hz, 1H, H-3b), 4.43 (dddd, J = 7.5 Hz, J = 6.6 Hz, J =
6.0 Hz, J = 3.0 Hz, 1H, H-2), 4.88 (dd, J = 10.5 Hz, J = 7.5 Hz, 1H, H-
1), 5.19-5.01 (m, 4H, CH2OP), 7.39–7.33 (m, 10H, Ar-H); 13C-NMR
(75.5 MHz, CDCl3) d [ppm]: 24.1, 24.2, 25.3, 35.2, 36.1, 39.5, 65.6
(d, J = 3.0 Hz,C-3), 69.0 and 69.7 (2d, J = 6.8 Hz, CH2OP), 73.9 (d, J =
9.0 Hz, C-2), 77.5 (d, J = 162.2 Hz, C-1), 111.1, 128.4, 128.5, 128.8,
128.9, 128.9, 135.3 and 135.6 (2d, J = 6.0 Hz, Cipso); 31P-NMR
(121.5 MHz, CDCl3) d [ppm]: 16.30. Anal. calcd. for C24H31O8P-
S60.5 H2O: C, 55.48; H, 6.21. Found: C, 55.77; H, 6.01.
69.6 (2d, J = 6.8 Hz, CH2OP), 70.7 (d, J = 3.0 Hz, C-2), 76.1 (d, J =
166.0 Hz, C-1), 128.5, 128.8, 128.8, 129.0, 129.8, 135.2 and 135.5
(2d, J = 7.5 Hz, Cipso); 31P-NMR (121.5 MHz, CDCl3) d [ppm]: 18.83.
Anal. calcd. for C18H23O8PS60.5 H2O: C, 53.07; H, 5.94. Found: C,
53.11; H, 5.94.
Dibenzyl (1S,2R)-2,3-dihydroxy-1-
mesyloxypropylphosphonate 5
As described in general procedure, from phosphonate (1S,2R)-4
(0.891 g, 1.75 mmol) and aqueous trifluoroacetic acid (4.60 mL),
the diol (1S,2R)-5 (0.488 g, 70%) was obtained as a white amor-
phous powder after crystallization from chloroform / hexane;
20
M.p.: 52–538C; ½aꢀD = + 10.9 (c = 1.2, CHCl3); IR (KBr) m [cm– 1]: 695,
730, 979, 1129, 1176, 1226, 1349, 2927, 3337, 3397; 1H-NMR
(300 MHz, CDCl3) d [ppm]: 2.85–2.65 (brs, 2H, OH), 2.99 (s, 3H,
CH3SO2), 3.75 (dd, J = 12.1 Hz, J = 4.4 Hz, 1H, H-3a), 3.85 (dd, J =
12.1 Hz, J = 2.6 Hz, 1H, H-3b), 4.09 (dddd, J = 10.7 Hz, J = 6.6 Hz, J =
4.4 Hz, J = 2.6 Hz, 1H, H-2), 5.00 (dd, J = 9.6 Hz, J = 6.6 Hz, 1H, H-1),
5.13–5.03 (m, 4H, CH2OP), 7.40–7.27 (m, 10H, Ar-H); 13C-NMR
(75.5 MHz, CDCl3) d [ppm]: 39.0, 62.1 (d, J = 6.6 Hz, C-3), 69.2 and
69.7 (2d, J = 6.8 Hz, CH2OP), 70.8 (d, J = 3.7 Hz, C-2), 76.4 (d, J =
164.6 Hz, C-1), 128.4, 128.5, 128.8, 128.9, 129.0, 135.3 and 135.5
(2d, J = 6.0 Hz, Cipso); 31P-NMR (121.5 MHz, CDCl3): d [ppm] 19.28.
Anal. calcd. for C18H23O8PS61.5 H2O: C, 50.83; H, 6.16. Found: C,
50.60; H, 5.86.
Dibenzyl (1S,2R)-2,3-O-cyclohexylidene-1-mesyloxy-2,3-
dihydroxypropylphosphonate 4
As described in the general procedure, from phosphonate
(1S,2R)-3 (2.01 g, 4.65 mmol) and mesyl chloride (0.73 mL,
9.3 mmol) in the presence of NEt3 (1.94 mL, 13.9 mmol), the
mesylate (1S,2R)-4 (1.87 g, 79%) was obtained as white needles
after crystallization from diethyl ether / hexane; M.p.: 81–828C;
20
½aꢀD = +17.5 (c = 1.3, CHCl3); IR (KBr) m [cm– 1]: 699, 743, 1019,
1181, 1262, 1363, 2853, 2939; 1H-NMR (300 MHz, CDCl3) d [ppm]:
1.61–1.38 (m, 10Hcyclohex.), 3.08 (s, 3H, CH3SO2), 3.93 (dd, J = 8.7 Hz,
J = 7.5 Hz, 1H, H-3a), 4.01 (dd, J = 8.7 Hz, J = 6.6 Hz, 1H, H-3b), 4.44
(dddd, J = 7.5 Hz, J = 6.6 Hz, J = 3.3 Hz, J = 1.2 Hz, 1H, H-2), 5.11–
5.01 (m, 4H, CH2OP), 5.16 (dd, J = 11.4 Hz, J = 3.3 Hz, 1H, H-1),
7.38–7.32 (m, 10H, Ar-H); 13C-NMR (75.5 MHz, CDCl3) d [ppm]:
23.9, 24.1, 25.3, 34.9, 35.9, 39.5, 64.5 (d, J = 2.3 Hz, C-3), 69.0 and
69.3 (2d, J = 7.5 Hz, CH2OP), 73.3 (d, J = 9.8 Hz, C-2), 74.7 (d, J =
165.2 Hz, C-1), 110.5, 128.4, 128.5, 128.8, 129.0, 129.2, 135.3 and
135.4 (2d, J = 6.0 Hz, Cipso); 31P-NMR (121.5 MHz, CDCl3) d [ppm]:
17.15. Anal. calcd. for C24H31O8PS: C, 56.46; H, 6.12. Found: C,
56.62; H, 6.25.
Dibenzyl (1R,2R)-2-hydroxy-1-mesyloxy-3-
trityloxypropylphosphonate 6
To a solution of the diol (1R,2R)-5 (0.35 g, 0.89 mmol) in CH2Cl2
(20 mL) cooled to 08C, trityl chloride (0.298 g, 1.07 mmol) was
added, followed by NEt3 (0.20 mL, 1.4 mmol) and DMAP (0.003 g,
0.03 mmol). Then, the solution was stirred at room temperature
for 20 h and later treated with cooled saturated NH4Cl (20 mL).
The aqueous layer was extracted with CH2Cl2 (3615 mL), organic
phases were combined and dried over MgSO4. After concentra-
tion, the crude product was chromatographed on a silica gel col-
umn with chloroform / methanol / triethylamine (100 : 1 : 0.05,
v / v) to give the trityl derivative (1R,2R)-6 (0.360 g, 60%) as a col-
General procedures for the preparation of 2,3-dihydroxy-
1-mesyloxypropylphosphonate 5
Solutions of phosphonates in 70% aqueous trifluoroacetic acid
were vigorously stirred at room temperature for 2 h. The vola-
tiles were evaporated and the residues were dissolved in CH2Cl2,
neutralized with solid NaHCO3 and finally dried over MgSO4.
After removal of the solids, the solutions was concentrated and
the crude products were chromatographed on a silica gel col-
umn with chloroform / methanol (100 : 1, v / v) to give the corre-
sponding diols.
20
ourless oil; ½aꢀD = –8.0 (c = 1.6, CHCl3); IR (film) m [cm– 1]: 699, 745,
1
1008, 1156, 1217, 1363, 2889, 2936, 3033, 3061,3354; H-NMR
(300 MHz, CDCl3) d [ppm] 2.86 (s, 3H, CH3SO2), 3.05-2.90 (brs, 1H,
HO), 3.31 (dd, J = 9.6 Hz, J = 6.0 Hz, 1H, H-3a), 3.41 (dd, J = 9.6 Hz, J
= 6.0 Hz, 1H, H-3b), 4.20–4.05 (m, 1H, H-2), 5.13–4.94 (m, 4H,
CH2OP), 5.14 (dd, J = 10.8 Hz, J = 3.6 Hz, 1H, H-1), 7.40–7.20 (m,
25H, Ar-H); 13C-NMR (75.5 MHz, CDCl3) d [ppm]: 39.1, 63.4 (d, J =
9.2 Hz, C-3), 69.6 and 68.7 (2d, J = 7.0 Hz, CH2OP), 69.5 (s, C-2), 75.7
(d, J = 167.5 Hz,C-1), 87.6, 127.1, 127.4, 127.7, 128.0, 128.3, 128.4,
128.6, 128.7, 128.8, 128.8, 128.9, 135.6 and 135.9 (2d, J = 5.9 Hz,
Cipso), 143.4; 31P-NMR (121.5 MHz, CDCl3) d [ppm]: 18.85. Anal.
calcd. for C37H37O8PS6H2O: C, 64.34; H, 5.69. Found: C, 64.64; H,
5.56.
Dibenzyl (1R,2R)-2,3-dihydroxy-1-
mesyloxypropylphosphonate 5
According to the general procedure, phosphonate (1R,2R)-4
(0.668 g, 1.31 mmol) in 70% aqueous trifluoroacetic acid
(4.56 mL) was vigorously stirred at room temperature for 2 h
and the diol (1S,2R)-5 (0.383 g, 73%) was obtained as white nee-
dles after crystallization from chloroform / hexane; M.p.: 93–
20
94.58C; ½aꢀD = –10.0 (c = 1.0, CHCl3); IR (KBr) m [cm– 1]: 695, 730,
Dibenzyl (1S,2R)-1,2-epoxy-3-
trityloxypropylphosphonate 7
1000, 1105, 1178, 1224, 1361, 2887, 2932, 3322, 3395, 3462; 1H-
NMR (300 MHz, CDCl3) d [ppm]: 3.01 (s, 3H, CH3SO2), 3.71 (dd, J =
12.0 Hz, J = 6.0 Hz, 1H, H-3a), 3.83 (ddd, J = 12.0 Hz, J = 5.1 Hz, J =
1.2 Hz, 1H, H-3b), 4.10 (dddd, J = 6.0 Hz, J = 5.4 Hz, J = 5.1 Hz, J =
4.2 Hz, 1H, H-2), 5.03 (dd, J = 11.7 Hz, J = 4.2 Hz, 1H, H-1), 5.18–
5.05 (m, 4H, CH2OP), 7.38–7.32 (m, 10H, Ar-H); 13C-NMR
(75.5 MHz, CDCl3) d [ppm]: 39.0, 62.4 (d, J = 8.3 Hz, C-3), 69.1 and
To a solution of the trityl derivative (1R,2R)-6 (0.43 g, 0.64 mmol)
in THF (4 mL) anhydrous K2CO3 (0.13 g, 0.96 mmol) was added
and the suspension was vigorously stirred at room temperature
for 20 h. After removal of potassium carbonate by filtration
through a layer of Celite, the solution was concentrated and the
crude product was chromatographed on a silica gel column
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www.archpharm.com

526
A. E. Wrꢀblewski et al.
Arch. Pharm. Chem. Life Sci. 2009, 342, 521–527
with chloroform / methanol / triethylamine (100: 1 : 0.05, v / v)
dimethylsulfoxide (DMSO – analytical grade) were prepared at a
concentration of 5000 lg/mL and sterilized by filtration. Series
of twofold dilutions were prepared in Mueller–Hinton broth in
a microtiter tray. Test strains (Staphylococcus aureus (ATCC 25923,
ATCC 6538P), Escherichia coli (ATCC 8739, ATCC 35218, ATCC
25922), Pseudomonas aeruginosa ATCC 27853, Bacillus subtilis
ATCC 6633, Enterococcus faecalis ATCC 29212) were then inocu-
lated to each well to achieve a final concentration of 106 organ-
ism per 1 mL. After 24 h of incubation at 378C, the increase of
turbidity was measured. The MIC values represent the lowest
concentrations of the investigated compounds with no measura-
ble bacterial growth increase.
to give the epoxyphosphonate (1S,2R)-7 (0.270 g, 73%) as a colour-
20
less oil; ½aꢀD = –10.7 (c = 1.9, CHCl3); IR (film) m [cm– 1]: 704 745,
1019, 1073, 1216, 1264, 1449, 1492, 2854, 2926, 3032, 3059; 1H-
NMR (300 MHz, CDCl3) d [ppm]: 3.01 (dd, J = 27.6 Hz, J = 4.5 Hz,
1H, H-1), 3.34 (dddd, J = 6.9 Hz, J = 6.3 Hz, J = 4.5 Hz, J = 3.0 Hz, 1H,
H-2), 3.51 (dd, J = 11.4 Hz, J = 3.0 Hz, 1H, H-3a), 3.59 (dd, J =
11.4 Hz, J = 6.9 Hz, 1H, H-3b), 4.97–4.85 (m, 4H, CH2OP), 7.61–
7.17 (m, 25H, Ar-H); 13C-NMR (75.5 MHz, CDCl3) d [ppm]: 49.2 (d, J
= 203.8 Hz, C-1), 56.8 (s, C-3) 62.9 (s, C-2), 68.0 and 68.3 (2d, J =
6.0 Hz, PhCH2OP), 87.3, 128.0, 128.0, 128.1, 128.1, 128.7, 128.7,
128.8, 136.9, 137.0, 143.8; 31P-NMR (121.5 MHz, CDCl3) d [ppm]:
20.01. Anal. calcd. for C36H33O5P: C, 74.99; H, 5.77. Found: C,
75.29; H, 5.58.
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Dibenzyl (1R,2R)-1,2-epoxy-3-
hydroxypropylphosphonate 8
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20
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1
2954, 3034, 3065, 3392; H-NMR (300 MHz, CDCl3) d [ppm]: 3.09
(dd, J = 30.9 Hz, J = 2.4 Hz, 1H, H-1), 3.36 (dddd, J = 4.8 Hz, J =
3.3 Hz, J = 2.7 Hz, J = 2.4 Hz, 1H, H-2), 3.56 (dd, J = 12.9 Hz, J =
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A
solution of the epoxyphosphonate (1R,2R)-8 (0.11 g,
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20
needles which decomposed after heating above 2008C; ½aꢀD
=
+7.2 (c = 1.1, H2O); IR (KBr) m [cm– 1]: 879, 976, 1061, 1085, 1228,
1323, 1395, 1535, 1633, 2548, 2599, 2642, 2701, 2857, 2943,
3428; 1H-NMR (250 MHz, CDCl3) d [ppm]: 1.75–1.60 (m, 2H,),
1.80–1.76 (m, 4H), 2.10–1.90 (m, 4H), 2.75 (dd, J = 21.6 Hz, J =
3.0 Hz, 1H, H-1), 3.12–3.07 (m, 1H), 3.26 (dddd, J = 5.8 Hz, J =
3.0 Hz, J = 2.5 Hz, J = 2.2 Hz, 1H, H-2), 3.49 (dd, J = 12.9 Hz, J =
5.8 Hz, 1H, H-3a), 3.92 (dd, J = 12.9 Hz, J = 2.2 Hz, 1H, H-3b); 13C-
NMR (62.9 MHz, CDCl3) d [ppm]: 21.9, 22.4, 28.5, 48.4, 50.3 (d, J =
175.8 Hz, C-1), 60.1, 65.5; 31P-NMR (101.3 MHz, CDCl3) d [ppm]:
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