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D. M. Springer et al. / Bioorg. Med. Chem. 11 (2003) 281–291
TFA (6 mL) is added and the mixture is stirred for 2 h.
The mixture is concentrated, and the reaction is found
to be incomplete. The material is redissolved in 60 mL
methylene chloride and treated with TFA (8 mL) for
another 1.5 h. The mixture is concentrated, and tritu-
rated with ether. The solids are collected and dissolved
in DMF, then re-precipitated with ether. The solids are
collected to afford the expected cephem diacid (1.60 g,
Synthesis of cephem 50. Cephem amine 2 (3.17 g, 7.64
mmol) is dissolved in 13 mL THF. Dicyclohexyl-
carbodiimide (1.58 g, 7.66 mmol) is added, followed by
acid 23 (2.58 g, 7.64 mmol). The mixture is stirred for
1.5 h at room temperature, and then filtered to remove
dicyclohexylurea. The filtrate is evaporated to afford the
expected chloromethyl cephem diester (5.52 g, 7.52
1
mmol; 98%) as an orange foam. H NMR (300 MHz,
1
2.80 mmol; 65%) as a tan solid. H NMR (300 MHz,
DMSO): d 9.36 (d, 1H, J=8 Hz, NH), 7.79 (d, 1H, J=1
Hz, ArH), 7.54 (d, 1H, J=1 Hz, ArH), 7.53–7.26 (m,
10H, ArH), 5.80 (dd, 1H, J=5, 8 Hz, R1R2CHNR3),
5.21 (d, 1H, J=5 Hz, CH(CNR)(SR)), 4.47–4.36 (m,
2H, CH2Cl), 4.00 (s, 2H, SCH2), 3.74 (d, 1H, J=17 Hz,
SCH), 3.56 (d, 1H, J=17 Hz, SCH), 1.54 (s, 9H,
(CH3)3).
DMSO): d 9.38 (d, 1H, J=8 Hz, NH), 7.90 (s, 1H,
ArH), 7.74 (s, 1H, ArH), 5.71 (dd, 1H, J=5, 8 Hz,
R1R2CHNR3), 5.16 (d, 1H, J=5 Hz, CH(CNR)(SR)),
4.63 (s, 2H, SO2CH2), 4.60–4.50 (m, 2H, CH2Cl), 4.09
(s, 2H, ArSCH2), 3.70 (d, 1H, J=17 Hz, RSCH2R),
3.52 (d, 1H, J=17 Hz, RSCH2R).
The above acid (0.350 g, 0.613 mmol) is dissolved in 3
mL DMF and 1-[3-(2,6-dimethyl-4-thioxo-4H-pyridin-
1-yl)-propyl]-2,3-dimethyl-3H-imidazol-1-ium; chloride
salt1 (0.180 g, 0.577 mmol) is added and the mixture
allowed to stir for 30 min at room temperature. Ether is
added to precipitate the crude product. The material is
re-dissolved in DMF (ꢀ2 mL) and triturated with
ether. The solids are collected and washed with ethyl
acetate and acetone, and then pumped dry to afford
crude cephem 34 as the dichloride salt. 1H NMR
(300 MHz, DMSO, partial): d 9.35 (d, 1H, J=8 Hz,
NH), 7.88 (s, 1H, ArH), 7.81 (s, 2H, pyrH), 7.76 (d, 1H,
J=2 Hz, imidazolium), 7.68 (s, 1H, ArH), 7.66 (d, 1H,
J=2 Hz, imidazolium), 5.66 (dd, 1H, J=5, 8 Hz,
R1R2CHNR3), 5.13 (d, 1H, J=5 Hz, CH(CNR)(SR)),
4.59 (s, 2H, SO2CH2), 3.76 (s, 3H, CH3), 2.73 (s, 6H, 2
X CH3), 2.64 (s, 3H, CH3).
The above cephem diester is dissolved in 25 mL meth-
ylene chloride, and 3 mL anisole. Trifluoroacetic acid (8
mL) is added, and a precipitate begins to form. The
suspension is stirred for 4.5 h and then filtered to afford
some of the desired diacid product. The filtrate is tritu-
rated with methylene chloride and ether, and filtered to
afford more product. The combined solids are stirred in
ethyl acetate overnight (ꢀ16 h), and then filtered and
pumped dry to afford the expected chloromethyl
cephem diacid (1.99 g, 3.89 mmol; 52%) as an off-white
solid. 1H NMR (300 MHz, DMSO): d 9.31 (d, 1H, J=8
Hz, NH), 7.84 (s, 1H, ArH), 7.54 (s, 1H, ArH), 5.71 (dd,
1H, J=5, 8 Hz, R1R2CHNR3), 5.13 (d, 1H, J=5 Hz,
CH(CNR)(SR)), 4.59–4.49 (m, 2H, CH2Cl), 3.99 (s, 2H,
SCH2), 3.71 (d, 1H, J=17 Hz, SCH), 3.52 (d, 1H, J=17
Hz, SCH).
The above chloromethyl cephem diacid (0.300 g, 0.586
mmol) is dissolved in 4 mL methanol. 1-[3-(2,6-Dime-
thyl-4-thioxo-4H-pyridin-1-yl)-propyl]-2,3-dimethyl-3H-
imidazol-1-ium; chloride salt1 (0.171 g, 0.549 mmol) is
added and the mixture allowed to stir for 1 h at room
temperature. The solvents are evaporated, and the
material is triturated with methylene chloride and ether.
The solid is collected and pumped dry to afford crude
The above dichloride salt of 34 is treated with 0.5 N
NaOH until the pH is ꢀ7.5, and the solution is then
chromatographed on C-18 silica gel, using water then
acetonitrile/water as eluants, to afford bis-zwitterion 34
(0.130 g, 0.157 mmol; 27%) as a light orange lyo-
.
phillate. Anal. (C33H35Cl2N5O8S4 3.8H2O) C, H, N.
1
Synthesis of cephem 38. Cephem diacid 4 (0.390 g, 0.701
mmol) is dissolved in 4 mL methanol and 2 mL meth-
ylene chloride, and 1-(2-hydroxy-ethyl)-1H-pyridine-4-
thione (0.101 g, 0.650 mmol) is added. After stirring at
room temperature for 1 h, the product is precipitated
with ether and collected. The material is dissolved in a
little DMF and triturated again with ether. The solid is
collected and washed with ether, ethyl acetate, and ace-
tone to afford crude cephem 38 (0.260 g) as the chloride
salt. This material is then dissolved in 0.5 N NaOH until
the pH is ꢀ7.5, and chromatographed on C-18 silica
gel, using water then acetonitrile/water as eluants, to
afford mono-sodium salt, mono-zwitterion 38 (0.170 g,
cephem 50 (0.295 g) as the dichloride salt. H NMR
(300 MHz, DMSO, partial): d 9.34 (d, 1H, J=8 Hz,
NH), 7.86 (s, 1H, ArH), 7.83 (s, 2H, pyrH), 7.80 (d, 1H,
J=2 Hz, imidazolium), 7.68 (d, 1H, J=2 Hz, imidazo-
lium), 7.56 (s, 1H, ArH), 5.70 (dd, 1H, J=5, 8 Hz,
R1R2CHNR3), 5.15 (d, 1H, J=5 Hz, CH(CNR)(SR)),
4.36–4.31 (m, 2H, CH2Cl), 4.05–3.95 (m, 2H, SCH2),
3.77 (s, 3H, CH3), 2.75 (s, 6H, 2ÂCH3), 2.66 (s, 3H,
CH3), 2.31–2.20 (m, 2H, CH2). MS (ESI) m/e 750
(MÀH)+.
The above material is dissolved in 1 N NaOH until the
pH is ꢀ8, and chromatographed on C-18 silica gel
using water and acetonitrile/water as eluants to afford
pure bis-zwitterion 50 (0.081 g, 0.108 mmol; 20%) as a tan
0.243 mmol; 37%) as a light yellow lyophillate. MS (ESI)
+
.
m/e 675 (M+H) . Anal. (C25H22Cl2N3Na1O7S4 3.0H2O)
C, H, N. 1H NMR (300 MHz, DMSO, partial): d 9.07 (d,
1H, J=8 Hz, NH), 8.63 (d, 2H, J=7 Hz, pyr), 8.35 (d,
2H, J=7 Hz, pyr), 7.45 (s, 1H, ArH), 7.35 (s, 1H, ArH),
5.38 (dd, 1H, J=5, 8 Hz, R1R2CHNR3), 4.90 (d, 1H,
J=5 Hz, CH(CNR)(SR)), 4.68 (d, 1H, J=14 Hz), 4.54–
4.42 (m, 2H), 4.30 (d, 1H, J=14 Hz), 3.78 (s, 2H), 3.82–
3.70 (m, 4H).
lyophillate. Anal. (C32H33Cl2N3O6S3 3.9H2O) C, H, N.
.
Synthesis of cephem 53. Cephem amine 2 (0.510 g, 1.24
mmol) is dissolved in 4 mL THF. DCC (0.269 g, 1.30
mmol) is added, followed by acid 31 (0.500 g, 1.24
mmol). The mixture is stirred for 1.5 h, and then filtered
to remove dicyclohexyl urea. The filtrate is evaporated,