Synthesis of glycosylated β-amino acids as new class of antitubercular agents

Article abstract of DOI:10.1016/S0223-5234(02)01398-3

A series of glycosylated β-amino acids was prepared and evaluated against Mycobacterium tuberculosis, M. avium, M. fortuitum and M. smegmatis. The compounds were designed to mimic the enzyme D-alanine racemase and glycosyl transferase involved in the bios

Full text of DOI:10.1016/S0223-5234(02)01398-3

European Journal of Medicinal Chemistry 37 (2002) 773Á781
/
www.elsevier.com/locate/ejmech
Preliminary communication
Synthesis of glycosylated b-amino acids as new class of antitubercular
agentsꢀ
R.P. Tripathi a,*, R. Tripathi a, V.K. Tiwari a, Laxmi Bala b, S Sinha b, A. Srivastava c,
R. Srivastava c, B.S. Srivastava c
a Division of Medicinal Chemistry, Central Drug Research Institute, Lucknow 226 001, India
b Division of Biochemistry, Central Drug Research Institute, Lucknow 226 001, India
c Division of Microbiology, Central Drug Research Institute, Lucknow 226 001, India
Received 3 January 2002; accepted 13 June 2002
Abstract
A series of glycosylated b-amino acids was prepared and evaluated against Mycobacterium tuberculosis, M. avium, M. fortuitum
and M. smegmatis. The compounds were designed to mimic the enzyme D-alanine racemase and glycosyl transferase involved in the
biosynthesis of essential cell wall peptidoglycan and arabinogalactan. Though most of the compounds exhibited little activity,
however, one showed significant activity against all the strains in cell culture and activity was confirmed by BACTEC method.
´
# 2002 Editions scientifiques et me´dicales Elsevier SAS. All rights reserved.
Keywords: Tuberculosis; Glycosyl amino acids; Conjugate addition
1. Introduction
natural
target for antitubercular drug development [8,9]. Inhi-
bitors of this enzyme such as, -cycloserine (a cyclic
analog of -alanine) and fludalanine are found to be
L- to D-alanine and has been identified as novel
Tuberculosis (T.B.) is the most prevalent infectious
disease worldwide and a leading killer caused by a single
infectious agent i.e. Mycobacterium tuberculosis [1,2]. As
a consequence of HIV epidemic and the lack of potency
of multi-drug regimens, drug resistance has become
more evident and the development of novel mechanism
based antitubercular agents has become a high priority
area globally [3,4]. The mycobacterial cell wall is an
effective barrier that contributes to drug resistance [5].
Inhibition of cell wall biosynthesis is not only a potential
antimycobacterial strategy but it also increases the
susceptibility of the bacteria to other antimycobacterial
agents [6]. The cell wall is dominated by covalently
D
D
active against M. tuberculosis both in vitro and in vivo
[10], but because of toxicity none of them found their
way to clinics [11]. Very recently, certain sugar deriva-
tives and glycofuranose analogs have been reported to
show significant anti T.B. and other biological activities
[12Á17]. Since last 40 years none of the new chemical
/
entity has been appeared against this disease. Keeping in
mind the above and the ability of sugars to offer better
stability [18], better pharmacokinetics [19], better trans-
port [20] and above all the less toxicity we were
prompted to develop novel, selective and more potent
glycosylated amino acid derivatives as antitubercular
agents.
linked mycolic acids (complimented by glycolipids),
arabinogalactan and peptidoglycan. -Amino acids are
important constituents of mycobacterial cell wall [7]. A
cytoplasmic enzyme -alanine racemase is required in
D-
D
We envisaged that such compounds might be effective
inhibitors of D-alanine racemase and D-alanylalanine
D
the initial step of peptidoglycan biosynthesis to convert
synthetase, and being glycofuranosylated at the b-
position these amino acid derivatives have chances to
interfere the glycosyltransferase activity of M. tubercu-
losis. It was further contemplated that introducing the
hydrophobic component would help in ligand binding
ꢀ CDRI communication No. 6067.
* Correspondence and reprints
E-mail address: rpt_56@yahoo.com (R.P. Tripathi).
´
0223-5234/02/$ - see front matter # 2002 Editions scientifiques et me´dicales Elsevier SAS. All rights reserved.
PII: S 0 2 2 3 - 5 2 3 4 ( 0 2 ) 0 1 3 9 8 - 3

774
R.P. Tripathi et al. / European Journal of Medicinal Chemistry 37 (2002) 773Á781
/
enoates (2) were derived from 1,2-O-isopropylidene-3-
O-benzyl(methyl)-xylofuranos-5-ulose (1) either by Wit-
tig olefination with carbethoxymethylene triphenylpho-
phorane or with triethylphosphonoacetate [20,21]. In the
former a mixture of (E) and (Z) in (90:10) ratio was
obtained, however in the latter only (E) form was
obtained in stereo-specific manner. Subsequently, 1,4-
conjugate addition of different primary amines [viz.
NH3, benzyl-, n-butyl-, n-dodecyl-, n-hexadecyl-, 1,5-
dimethyl hexyl-, 2-(carbethoxy)-ethyl- and 3-(car-
bethoxy)-propylamines] to the above esters 2 led to the
Fig. 1. Synthesis of glycosylated amino esters and acids. Reagents and
conditions: (i) carbethoxymethylenetriphenylphosphorane, dry ben-
zene, reflux, 12 h; (ii) triethylphosphonoacetate, LiOH, dry THF, r.t.,
corresponding glycosylated b-amino esters (3Á
/
18) in
excellent yield. LiOH mediated hydrolysis led to the Li
10 h; (iii) amines, ethanol, r.t., 3Á
/
10 h; (iv) triethyl amineÁ
/
waterÁ
/
salt of the corresponding acids. However, the free acids
ethanol (2:2:1), r.t., 3 days or LiOH, THFÁ
/
water (1:1), 0.5 h, r.t.
(19Á22) could be obtained by treatment of amino esters
/
(3, 4, 9 and 11) with aqueous ethanolic triethylamine.
Since compounds 9 and 11 (both as diastereoisomeric
mixture) were the most active compounds, the indivi-
dual isomers of compounds 9 and 11 were separated
using column chromatography as the major and minor
isomers.
Compounds R
NR1R2
Ratio
of major
and
minor
isomers
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
CH3
CH2Ph NH2
CH3 PhCH2NH
CH2Ph PhCH2NH
NH2
65:35
75:25
65:35
80:20
65:35
75:25
64:36
76:24
64:36
76:24
3. Results and discussion
The conjugate addition of amines to ester 2 was
diastereoselective as two diastereoisomers were obtained
1
in different ratios as evident by H-NMR spectral data
CH3
CH2Ph n-butylÃ
CH3
CH2Ph n-dodecylÃ
CH3
CH2Ph n-hexadecylÃ
CH3
1,5-dimethylhexylÃ
CH2Ph 1,5-dimethylhexylÃ
CH3
2-carbethoxyethylÃ
CH2Ph 2-carbethoxyethylÃ
CH3
CH2Ph 3-carbethoxypropylÃ
CH3 NH2
CH2Ph NH2
n-butylÃ
/
NH
/NH
n-dodecylÃ
/
NH
of glycosylated amino esters (3Á18). Explanation can be
/
/NH
rationalised in terms of Felkin-Anh like transition
states. Four transition states for the olefinic ester can
be considered as shown in Fig. 2. In conformations I
n-hexadecylÃ
/
NH
NH
/
/
NH 65:35
NH 75:25
NH 60:40
NH 70:30
NH 60:40
NH 80:20
and II, the more electronegative CÃ/O group of the
/
furanose ring, whereas in III and IV the C-3 substituent
(bezyloxy or methyl) were placed at right angles to the
double bond. In such a model it is known that
nucleophile should attack from the side opposite to
the olefinic double bond. In case of benzyloxy sub-
stituent ‘re’ face attack of nucleophile to the double
/
/
3-carbethoxypropylÃ
/
/
bond in conformer I (to give the
face attack in conformer II (to give the
D
-gluco isomer) and ‘si’
-ido isomer) is
CH3
CH3
n-dodecylÃ
n-hexadecylÃ
/NH
L
/
NH
hindered by C-3 substituent. Therefore, conformers III
and IV should be considered. It is presumed that
conformer III has preference to the IV due to favourable
and the chelating moieties (Ã
/
COOEt and Ã
/
NH) might
alkeneÁ
Whereas ‘si’ face attack of amines by chelation with
furanose ring oxygen explains the formation of -ido
/
arene interactions as per Houck’s rule [22].
be involved in co-ordination with metal ions often found
in the enzyme’s active site.
L
isomer. However, in C-3 hydroxy or with non-bulky
substituent arene p-stacking effect is absent, therefore, it
is presumed that the furanose CÃ
/
O bond will adopt the
2. Chemistry
perpendicular position favoring the conformers I and II
would then lead to product formation. Thus major
isomer has ‘S’ configuration at C-5 while minor isomer
has ‘R’ configuration.
The approach towards the synthesis of the desired
glycosylated b-amino acid derivatives is represented in
Fig. 1. Ethyl-3-[3-O-benzyl(methyl)-1,2-O-isopropyli-
Most of the compounds showed marginal antimyco-
bacterial activity in MABA and micro-dilution techni-
dene-5-deoxy-a-
D-xylofuranos-5-yl]-carbethoxyprop-2-

R.P. Tripathi et al. / European Journal of Medicinal Chemistry 37 (2002) 773Á
/781
775
Table 1
Antitubercular activities of glycosylated b-amino acid derivatives 3Á
/
23
Compounds
MABA
(mg mLꢀ1
Agar microdilu-
tion
BACTEC
)
method
3
ꢀ25
ꢀ25
ND
ꢀ100
ꢀ100
ꢀ100
50
ND
ND
ND
ND
ND
ND
ND
ND
4
5
6
ND
ꢀ25
ND
7
ꢀ50
50
50
8
9
10
ꢀ25
ꢀ25
12.5
50
6.25
50
11
12
6.25
ꢀ25
ꢀ25
ꢀ25
ꢀ25
ꢀ25
ꢀ25
ꢀ25
ꢀ100
ꢀ100
ꢀ25
ꢀ50
ꢀ50
ꢀ100
3.12
ꢀ25
ND
ND
ND
ND
ND
50
13
14
ND
25
15
16
50
50
17
18
100
50
19
20
50
ND
ND
ꢀ50
ND
ND
ND
ND
50
21
22
100
100
ꢀ100
6.25
21
22
Major isomer of
11
6.25
Fig. 2. Felkin-Anh transition state model for reaction mechanism.
Minor isomer of ꢀ100
11
ꢀ100
ꢀ100
MIC, minimum inhibitory concentration; ND, not determined; MIC
of the compounds used as control: ethambutol 1.5Á
5 mg mLꢀ1
rifampicin 0.75 mg mLꢀ1, INH 0.65 mg mLꢀ1, ethionamide 10 mg
mLꢀ1
/
,
ques (Table 1). Two compounds with long alkyl chain (9
and 11) exhibited significant activities in all the three-
test system. Compound 11 caused complete inhibition of
M. tuberculosis strain at 6.25 mg mLꢀ1. This compound
showed very good activity in all the three strains of
mycobacteria (M. avium, M. smegmatis and M. tuber-
culosis) at one or the other concentrations. The activity
in compound 11 was confirmed using the BACTEC
technique also, where the MIC was found to be 6.25
mg mLꢀ1. However, the activity in compound 11 is due
.
4. Conclusion
In conclusion, we have shown glycosylated b-amino
esters as novel class of antimycobacterial agents. The
mechanism for the activity of these compounds against
the mycobacteria is unclear. It is speculated that these
compounds might be acting either by interfering in the
cell wall biosynthesis by inhibiting the crucial enzymes
to major diastereoisomer (b-
L-ido isomer) only with
(glycosyl transferase or D-alanine racemase) or through
MIC of 6.25 mg mLꢀ1, while the minor isomer (a-
D-
some immune modulation mechanism. The exact mode
of action of these compounds is under investigation and
will be reported in future communication.
gluco isomer) was found to be inactive in BACTEC
method.
On careful examination of the biological results, it is
clear that glycosyl amino esters having long chain alkyl
groups as amine substituent are more active than the
short chain alkyl group. Conversion of glycosylated
amino esters (3, 4, 9 and 11) into corresponding acids
5. Experimental
5.1. Biological activity
(19Á22) results in drastic loss in antimycobacterial
/
activity. Replacement of 3-O-methyl (9) with 3-O-
benzyl (10) reduces the activity. Further replacement
of amino function either with short or branched chain
MICs of the test compounds were determined using
three different techniques i.e. MABA assay, agar
microdilution method and BACTEC 460-TB system.
For MABA assay M. tuberculosis, H37Ra was used
as a suitable surrogate for the virulent H37 Rv strain.
alkyl group or with b-amino ester (15Á/18) increases
antitubercular activity profile in comparison to the
corresponding amino esters.
Young (7Á8 days) cultures were diluted in liquid
/

776
R.P. Tripathi et al. / European Journal of Medicinal Chemistry 37 (2002) 773Á781
/
medium to provide, an optimal density of 0.02 at 550 nm
spectrophotometrically which gave colour change of
Alamar blue ‘oxidation reduction’ dye (blue to pink) in
5.2.1. General procedure for the preparation of
compounds 3 and 4
7Á8 days. The standard antitubercular agents Rifamy-
/
cin, isoniazid, p-aminosalicylic acid, ethambutol and
ethionamide were taken as positive controls. The screen-
ing of the compounds was carried out as reported earlier
[23].
5.2.1.1. Ethyl-[5-amino-3-O-methyl-5,6-dideoxy-1,2-O-
isopropylidene]-a-
(3). Ethyl-[3-O-methyl-5,6-dideoxy-1,2-O-isopropyli-
dene-a- -gluco]-heptfuran-5-en-uronate (3 g, 11.494
D-gluco- and b-L-ido-heptofuranurnate
D
In agar microdilution method serial twofold dilutions
of each test compound was added into 7H10 agar and
M. tuberculosis H37 Rv was used as test organism. The
test was performed as reported by Saita et al. [24]. Stock
solution of the test compounds prepared in DMSO at 1
mg mLꢀ1 was sterilised by passage through 0.22 mm
filters. Fifty microliters were added to 4 mL radiometric
7H12 Broth (BACTEC 12B; Becton Dickinson Diagnos-
tic Instrument System, US) to achieve final concentra-
tions. Controls received 50 mL DMSO. Ofloxacin,
streptomycin and rifampicin (Sigma Chemical Co., St.
Louis, MO) were included as positive drug control.
In BACTEC method, M. tuberculosis H37 Rv was
mmol) and ethanolic ammonia (25 mL) was magneti-
cally stirred in a closed vessel for 24 h. Solvent and
excess of NH3 were evaporated under reduced pressure.
The crude product, thus obtained, was chromato-
graphed over SiO2 column using CHCl3ÁMeOH (98:2)
/
as eluant to give the above compound as colourless oil
(diastereoisomeric mixture ratio 65:35).
Colourless oil (90% yield); IR (KBr, cmꢀ1): nmax 3382
(NH2), 1720 (ÈCÄ
1H-NMR (CDCl3): d 5.91 and 5.90 (each d, Jꢃ
each 1H, diastereoisomeric H-1), 4.60 (d, Jꢃ3.7 Hz,
1H, H-2), 4.10 (q, Jꢃ7 Hz, 2H, OCH2CH3), 3.98 (d,
Jꢃ2.8 Hz, 1H, H-4), 3.82 (d, Jꢃ2.8 Hz, 1H, H-3), 3.52
(m, 1H, H-5), 3.39 (s, 3H, ÃOCH3), 2.40 (m, 2H, H-6),
1.80 (bs, 2H, NH2), 1.48, 1.32 [each s, each 3H,
ÈC(CH3)2], 1.26 (t, Jꢃ7 Hz, 3H, Ã
OCH2CH3); 13C-
NMR (CDCl3): O), 111.85
172.06 (ÈCÄ
[ÈC(CH3)],105.09 and 105.03 (C-1), 84.57 (C-2), 82.22
(C-4), 81.56 (C-3), 60.73 (ÃOCH2CH3), 57.84 (ÃOCH3),
47.42 (C-5), 38.69 (C-6), 27.04 and 26.58 [ÈC(CH3),
14.49 (ÃOCH2CH3). Anal. C13H23NO6 (C, H, N).
/
O); MS (FAB): m/z 290 [Mꢂ
/
H]ꢂ;
/
3.7 Hz,
/
/
/
/
scraped from fresh LowensteinÁJensen slants resus-
/
/
pended in 3 mL diluting fluid and homogenised with
glass beads (2 mm). Homogenous supernatant was
taken, turbidity was adjusted to mcFarland 1 with
diluting fluid and 0.1 mL injected into a BACTEC 12B
vial which was used as a primary inoculum after growth
/
/
d
/
/
/
index (GI) of 0 reached to 500Á700. This suspension (0.1
/
mL) was used to inoculate 4 mL fresh BACTEC 12B
broth containing the test compounds. An additional
control vial was included which received a further 1:100
inoculum. Cultures were incubated at 37 8C and the GI
determined daily. When the GI of 1:100 control vials
reached 30, the test was read for an additional day and
then terminated. If the drug difference in the GI values
from the previous day (called DGI) in case of drug
containing vials was less than DGI of the 1:100 control,
/
5.2.1.2. Ethyl-[5-amino-3-O-benzyl-5,6-dideoxy-1,2-O-
isopropylidene]-a- -gluco- and b- -ido-heptofuranurnate
(4). It was obtained by reaction of ethyl-[3-O-benzyl-
5,6-dideoxy-1,2-O -isopropylidene-a- -gluco]-hept-
D
L
D
furan-5-en-uronate and ethanolic ammonia as described
above to give diastereoisomeric mixture ratio (75:25) of
4 as colourless oil (90% yield); IR (KBr, cmꢀ1): nmax
then the bacteria was defined as 1ꢀ
sample/GI of control)ꢁ100. Assays were completed in
5Á8 days and were carried out according to literature
/(GI of the test
/
/
3382 (NH2), 1720 (COOEt); MS (FAB): m/z 366 [Mꢂ
1]ꢂ; 1H-NMR (CDCl3): d 7.32 (bs, 5H, ArH), 5.94 and
5.92 (each d, Jꢃ3.7 Hz, each 1H, diastereoisomeric H-
1), 4.69 (d, Jꢃ11.9 Hz, 1H, ÃOCHAAr), 4.65 (d, Jꢃ3.7
Hz, 1H, H-2), 4.44 (d, Jꢃ11.9 Hz, 1H, ÃOCHBAr),
4.09 (q, Jꢃ7 Hz, 2H, OCH2CH3), 3.99 (d, Jꢃ2.9 Hz,
1H, H-4), 3.87 (d, Jꢃ2.9 Hz, 1H, H-3), 3.59 (m, 1H, H-
5), 2.26 (m, 2H, H-6), 1.70 (bs, 2H, NH2), 1.48, 1.32
[each s, each 3H, C(ÈCH3)2], 1.25 (t, Jꢃ7 Hz, 3H,
OCH2CH3); 13C-NMR (CDCl3): d 172.12 (ÈCÄ
O),
137.37, 129.09, 128.94 and 128.32 (ArÃC), 112.09
[ÈC(CH3), 105.47 and 105.20 (C-1), 83.77 (C-2), 82.58
(C-4), 81.96 (C-3), 72.03 (ÃOCH2Ar), 60.82
(ÃOCH2CH3), 47.82 (C-5), 38.65 (C-6), 27.14 and
26.69 [ÈC(CH3), 14.59 (ÃOCH2CH3). Anal.
C19H27NO6 (C, H, N).
/
procedure [25].
/
/
/
/
5.2. Chemistry
/
/
/
/
M.P.s were determined on a Buchi 510 apparatus and
are uncorrected. Elemental analysis for all new com-
pounds were performed on a Carlo Erba Model 1108
elemental analyser and data of C, H, and N is within 9
0.4% of calculated values. Thin layer chromatography
was used to monitor the reactions. IR spectra were
/
/
/
Ã
/
/
/
recorded using PerkinÁElmer 881 spectrophotometer
/
and the values are expressed as nmax cmꢀ1. Mass
spectral data were run on JEOL-300 spectrophotometer
and PMR spectra were recorded on Bruker 200 and 300
MHz spectrophotometer.
/
/
/

R.P. Tripathi et al. / European Journal of Medicinal Chemistry 37 (2002) 773Á
/781
777
5.2.2. General procedure for the preparation of
compounds 5Á18
5.2.2.2. Ethyl-[3-O-benzyl-5,6-dideoxy-5-benzylamino-
1,2-O-isopropylidene]-a- -gluco and b- -ido-
heptofurannuronate (6). Minor isomer: Colourless oil
(25% yield); IR (KBr, cmꢀ1): nmax 3350 (Ã
NH), 3020,
2980, 2920 (CH3 and CH2 stretching), 1710 (ÈCÄO);
MS (FAB): m/z 456 [Mꢂ
1]ꢂ; 1H-NMR (200 MHz,
CDCl3): d 7.26 (m, 10H, ArÃH), 5.89 (d, Jꢃ3.77 Hz,
1H, H-1), 4.67 (d, Jꢃ11.72 Hz, 1H, ÃOCHAPh), 4.59
(d, Jꢃ3.7 Hz, 1H, H-2), 4.53 (d, Jꢃ11.69 Hz, 1H,
OCHBPh), 4.23 and 4.17 (dd, Jꢃ7.0 and 2.7 Hz, 1H,
H-4), 4.12 (q, Jꢃ7.2 Hz, 2H, ÃOCH2CH3), 4.08 (d, Jꢃ
3.2 Hz, 1H, H-3), 3.85 (d, Jꢃ12.8 Hz, 1H,
NHCHAPh), 3.72 (d, Jꢃ12.8 Hz, 1H, ÃNHCHBPh),
3.52 (m, 1H, H-5), 2.85 and 2.78 (dd, Jꢃ15.6 and 4.4
Hz, 1H, H-6A), 2.62 and 2.54 (dd, Jꢃ15.6 and 6.7 Hz,
1H, H-6B), 1.68 (s, 1H, ÃNHCH2Ph), 1.47 and 1.31
[each s, each 3H, ÈC(CH3)2], 1.24 (t, Jꢃ7.14 Hz, 3H,
OCH2CH3); 13C-NMR (CDCl3): d 172.15 (ÈCÄ
O),
141.07, 137.52, 128.92, 128.73, 128.66, 128.47, 128.32
and 127.19 (each ArÃC), 112.01 [ÈC(CH3)2], 105.29 (C-
1), 82.76 (C-2), 82.26 (C-4), 82.19 (C-3), 71.91
(ÃOCH2Ph), 60.80 (ÃOCH2CH3), 54.23 (C-5), 52.02
(ÃNHCH2Ph), 36.91 (C-6), 27.19 and 26.75 [2ꢁ
ÈC(CH3)2], 14.62 (ÃOCH2CH3).
Major isomer: Yellow solid (m.p. 74 8C); IR (KBr,
cmꢀ1): nmax 3350 (Ã
NH), 3020, 2980, 2920 (CH3 and
CH2 stretching), 1710 (ÈCÄO); MS (FAB): m/z 456
[Mꢂ
H]ꢂ; 1H-NMR (200 MHz, CDCl3): d 7.25 (m,
10H, ArÃH), 5.94 (d, Jꢃ3.89 Hz, 1H, H-1), 4.69 (d,
Jꢃ11.82 Hz, 1H, ÃOCHAPh), 4.64 (d, Jꢃ3.93 Hz, 1H,
H-2), 4.44 (d, Jꢃ11.8 Hz, 1H, ÃOCHBPh), 4.25 and
4.19 (dd, Jꢃ8.8 and 3.2 Hz, 1H, H-4), 4.10 (q, Jꢃ7.14
Hz, 2H, ÃOCH2CH3), 3.94 (d, Jꢃ3.19 Hz, 1H, H-3),
3.84 (s, 2H, ÃNHCH2Ph), 3.52 (m, 1H, H-5), 2.46 and
2.40 (dd, Jꢃ15.6 and 4.7 Hz, 1H, H-6A), 2.34 and 2.28
(dd, Jꢃ15.6 and 6.6 Hz, 1H, H-6B), 1.68 (bs, 1H,
NHCH2Ph), 1.47 and, 1.31 [each s, each 3H,
ÈC(CH3)2], 1.24 (t, Jꢃ7.14 Hz, 3H, ÃOCH2CH3);
13C-NMR (CDCl3): d 172.80 (ÈCÄ
O), 141.07, 137.97,
128.86, 128.69, 128.42, 128.26, 128.12 and 127.27 (each
ArÃC), 111.98 [ÈC(CH3)2], 105.20 (C-1), 82.60 (C-2),
82.40 (C-4), 82.22 (C-3), 72.49 (ÃOCH2Ph), 60.66
(ÃOCH2CH3), 53.07 (C-5), 51.67 (ÃNHCH2Ph), 36.26
(C-6), 27.22 and 26.78 [2ꢁÈC(CH3)2], 14.57
(ÃOCH2CH3). Anal. C26H33NO6 (C, H, N).
/
D
L
/
5.2.2.1. Ethyl-[3-O-methyl-5,6-dideoxy-5-benzylamino-
1,2-O-isopropylidene]-a- -gluco and b- -ido-
/
D
L
/
heptofurannuronates (5). A solution of (1R, 2R, 3S,
4R)-ethyl-(3-O-methyl-1,2-isopropylidene-1,4-pentofur-
anose-4-yl)-hept-5-enoate (2.72 g, 10.0 mmol) dissolved
in EtOH (15 mL), was magnetically stirred with
benzylamine (1.16 mL, 10.8 mmol) at room temperature
(25 8C) for 40 h. Solvent was evaporated under reduced
pressure to get crude product. Column chromatography
/
/
/
/
/
/
Ã
/
/
/
/
/
/
Ã
/
/
/
(SiO2) of the crude product using C6H14Á
/
EtOAc (80:20)
/
as eluant afforded the diastereomeric compounds in
65:35 ratios. Over all, yield was 96%.
/
/
Minor isomer: Colourless oil (15% yield); IR (KBr,
/
cmꢀ1): nmax 3351 (Ã
/
NH), 3051, 2985, 2922 and 2848
(CH3 and CH2 stretching), 1721 (ÈCÄO); MS (FAB):
1]ꢂ; H-NMR (CDCl3): d 7.35 (m, 5H,
H), 5.90 (d, Jꢃ3.7 Hz 1H, H-1), 4.60 (d, Jꢃ3.7 Hz,
1H, H-2), 4.28 and 4.23 (dd, Jꢃ7.0 and 3.2 Hz, 1H, H-
4), 4.16 (q, Jꢃ7.14 Hz, 2H, ÃOCH2CH3), 3.89 (d, Jꢃ
12 Hz, 1H, ÃNHCHAPh), 3.80 (d, Jꢃ12 Hz, 1H,
NHCHBPh), 3.74 (d, Jꢃ3.2 Hz, 1H, H-3), 3.40 (m,
1H, H-5), 3.35 (s, 3H, ÃOCH3), 2.56 and 2.50 (dd, Jꢃ
15.6 and 4.7 Hz, 1H, H-6A), 2.47 and 2.40 (dd, Jꢃ15.6
and 4.7 Hz, 1H, H-6B), 1.88 (s, 1H, ÃNHCH2Ph), 1.49
and 1.30 [each s, each 3H, ÈC(CH3)2], 1.24 (t, Jꢃ7.14
Hz, 3H, Ã
OCH2CH3); 13C-NMR (CDCl3): d 172.76
(ÈCÄO), 141.15, 128.67, 128.51 and 127.28 (each ArÃ
C), 111.89 [ÈC(CH3)2], 105.13 (C-1), 84.17 (C-2), 82.36
(C-4), 82.26 (C-3), 60.67 (ÃOCH2CH3), 57.98 (ÃOCH3),
52.75 (C-5), 51.94 (ÃNHCH2Ph), 36.57 (C-6), 27.18 and
26.73 [2ꢁÈC(CH3)2], 14.63 (ÃOCH2CH3).
Major isomer: Colourless oil (75% yield); IR (KBr,
cmꢀ1): nmax 3355 (Ã
NH), 3048, 2978, 2923 and 2845
(CH3 and CH2 stretching), 1721 (ÈCÄO); MS (FAB):
m/z 380 [Mꢂ
1]ꢂ; 1H-NMR (400 MHz, CDCl3): d 7.32
(m, 5H, ArÃH), 5.90 (d, Jꢃ3.7 Hz, 1H, H-1), 4.57 (d,
Jꢃ3.7 Hz, 1H, H-2), 4.23 and 4.18 (dd, Jꢃ8.6 and 3.1
Hz, 1H, H-4), 4.18 (q, Jꢃ7.14 Hz, 2H, ÃOCH2CH3),
3.90 (d, Jꢃ12 Hz, 1H, ÃNHCHAPh), 3.85 (d, Jꢃ12
Hz, 1H, ÃNHCHBPh), 3.74 (d, Jꢃ3.2 Hz, 1H, H-3),
3.39 (m, 1H, H-5), 3.36 (s, 3H, ÃOCH3), 2.58 and 2.52
(dd, Jꢃ15.6 and 4.7 Hz, 1H, H-6A), 2.46 and 2.39 (dd,
Jꢃ15.6 and 6.6 Hz, 1H, H-6B), 2.02 (s, 1H,
NHCH2Ph), 1.47 and 1.30 [each s, each 3H,
ÈC(CH3)2], 1.25 (t, Jꢃ7.14 Hz, 3H, ÃOCH2CH3);
13C-NMR (CDCl3): d 172.12 (ÈCÄ
O), 140.96, 128.65,
127.18 (each ArÃC), 111.90 [ÈC(CH3)2], 105.18 (C-1),
84.55 (C-2), 82.83 (C-4), 81.59 (C-3), 60.77
(ÃOCH2CH3), 57.62 (ÃOCH3), 54.33 (C-5), 51.96
(ÃNHCH2Ph), 36.89 (C-6), 27.14 and 26.94 [2ꢁ
ÈC(CH3)2], 14.62 (ÃOCH2CH3). Anal. C20H29NO6
(C, H, N).
Ã
/
/
/
1
m/z 380 [Mꢂ
/
/
ArÃ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Ã
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Ã
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
5.2.2.3. Ethyl-[3-O-methyl-5,6-dideoxy-5-butylamino-
1,2-O-isopropylidene]-a- -gluco and b- -ido-
Ã
/
D
L
/
/
heptofurannuronate (7). Colourless oil (80% yield); IR
(KBr, cmꢀ1): nmax 2980, 2940, 2860, 2808 (CH3 and
/
/
CH2 stretching), 1720 (ÈCÄ
/
O); MS (FAB): m/z 346
1]ꢂ; H-NMR (CDCl3): d 5.91 (d, Jꢃ
3.7 Hz 1H,
H-1, major isomer), 5.87 (d, Jꢃ3.7 Hz 1H, H-1, minor
isomer), 4.60 (d, Jꢃ3.7 Hz, 1H, H-2, major isomer),
4.57 (d, Jꢃ3.7 Hz, 1H, H-2, minor isomer), 4.12 (q, Jꢃ
7.14 Hz, 2H, ÃOCH2CH3), 4.10 and 4.05 (dd, Jꢃ12
1
[Mꢂ
/
/
/
/
/
/
/
/
/
/
/
/
/

778
R.P. Tripathi et al. / European Journal of Medicinal Chemistry 37 (2002) 773Á781
/
and 8 Hz, 1H, H-4), 3.80 and 3.71 (d, Jꢃ
3), 3.38 (s, 3H, ÃOCH3), 3.32 (m, 1H, H-5), 2.67 (m, 2H,
NCH2), 2.50 and 2.45 (two dd, Jꢃ12 and 8 Hz 1H, H-
6A), 2.40 and 2.35 (two dd, Jꢃ12 and 8 Hz 1H, H-6B),
1.77 [bs, 1H, ÃNH(CH2)3CH3], 1.49 [s, 3H, ÈC(CH3)2],
1.42 [m, 2H, NH(CH2CH2)], 1.32 [m, 2H,
NH(CH2)2CH2)], 1.30 [s, 3H, ÈC(CH3)2], 1.27 (t,
Jꢃ7.14 Hz, 3H, ÃOCH2CH3), 0.90 [t, 3H, Jꢃ7.15
Hz, Ã
NH(CH2)3CH3]; 13C-NMR (CDCl3): d 172.20
(ÈCÄO), 112.16 [ÈC(CH3)2], 105.39 (C-1), 83.99 (C-2),
82.30 (C-4), 81.79 (C-3), 60.74 (ÃOCH2CH3), 54.76 (C-
5), 46.60 NHCH2), 33.24
(Ã
(ÃNHCH2CH2), 27.12 and 26.51 [2ꢁ
20.22 (ÃNHCH2CH2CH2CH3), 14.52 (Ã
13.91 [Ã
/
3.1 Hz, 1H, H-
3H, ÈC(CH3)2], 1.28 (m, 31H, methylene protons of
alkyl chain and ÃOCH2CH3), 0.90 (t, Jꢃ6.6 Hz, 3H,
alkyl CH2CH3); 13C-NMR (CDCl3): d 172.5 (ÈCÄ
O),
111.9 [ÈC(CH3)2], 104.6 (C-1), 84.8 (C-2), 81.9 (C-4),
81.4 (C-3), 60.2 (OCH2), 57.6 (OCH3), 52.5 (C-5), 47.7
(NHCH2), 36.7 (C-6), 32.3, 30.8, 30.0, 29.7, 26.7, 26.9
(alkyl CH2’s), 26.7 and 26.3 [ÈC(CH3)2], 14.2 and 14.1
(OCH2CH3 and alkyl CH2CH3).
/
/
/
Ã
/
/
/
/
/
Ã
/
Ã
/
/
/
/
/
Major isomer: Colourless oil (75% yield); IR (KBr,
/
cmꢀ1): nmax 3690 (Ã
/
NH), 2928, 2856, 2404 (CH3 and
CH2 stretching), 1724 (ester); MS (FAB): m/z 458 [Mꢂ
1]ꢂ; 1H-NMR (CDCl3): d 5.83 (d, Jꢃ
3.9 Hz, 1H, H-1),
4.51 (d, Jꢃ3.9 Hz, 1H, H-2), 4.08 (q, Jꢃ7.1 Hz, 2H,
OCH2), 4.02 (d, Jꢃ3.15 Hz, 1H, H-4), 3.65 (d, Jꢃ3.16
Hz, 1H, H-3), 3.31 (s, 3H, OCH3), 3.22 (m, 1H, H-5),
2.58 (dd, Jꢃ19.7 and 4.2 Hz, 1H, H-6A), 2.65 (m, 3H,
/
/
/
(C-6),
31.18
/
/
/
ÈC(CH3)2],
/
/
/
/
OCH2CH3),
/
/
/
NH(CH2)3CH3]. Anal. C17H31NO6 (C, H, N).
/
5.2.2.4. Ethyl-[3-O-benzyl-5,6-dideoxy-5-butylamino-
1,2-O-isopropylidene]-a- -gluco and b- -ido-
heptofurannuronate (8). Colourless oil (80% yield); IR
(KBr, cmꢀ1): nmax 3350 (Ã
NH), 3040, 2990, 2880 (CH3
and CH2 stretching), 1730 (ÈCÄO); MS (FAB): m/z
1]ꢂ; H-NMR (CDCl3): d 7.35 (m, 5H, ArÃ
H), 5.95 (d, Jꢃ3.7 Hz, 1H, H-1, major isomer), 5.87 (d,
Jꢃ3.7 Hz 1H, H-1, minor isomer), 4.72 (d, Jꢃ12 Hz,
1H, ÃOCHAPh), 4.65 (d, Jꢃ3.7 Hz, 1H, H-2, major
isomer), 4.60 (d, Jꢃ3.7 Hz, 1H, H-2, minor isomer),
4.45 (d, Jꢃ12 Hz, 1H, ÃOCHBPh), 4.14 (dd, Jꢃ12 and
8 Hz, 1H, H-4), 4.10 (q, Jꢃ7.14 Hz, 2H, ÃOCH2CH3),
3.90 (d, Jꢃ3.2 Hz, 1H, H-3), 3.40 (m, 1H, H-5), 2.65
(m, 2H, ÃNHCH2), 2.38 (dd, 1H, Jꢃ12 and 8 Hz, 1H,
H-6A), 2.25 (dd, Jꢃ12 and 7 Hz, 1H, H-6B), 1.72 [bs,
1H, ÃNH(CH2)3CH3], 1.50 [s, 3H, ÈC(CH3)2], 1.42 (m,
2H, ÃNHCH2CH2), 1.32 [s, 3H, ÈC(CH3)2], 1.30 [(m,
2H, NHCH2CH2CH2), 1.28 (t, Jꢃ7.1 Hz, 3H,
OCH2CH3), 0.88 (t, Jꢃ7.2 Hz, 3H, ÃNH(CH2)3CH3);
13C-NMR (CDCl3): d 172.20 (ÈCÄ
O), 137.51, 129.10,
128.42 and 128.14 (each ArÃC), 111.90 [ÈC(CH3)2],
105.21 (C-1), 82.63 (C-2), 82.26 (C-4), 82.12 (C-3), 71.88
(ÃOCH2Ph), 60.68 (ÃOCH2CH3), 54.44 (C-5), 47.34
(ÃNHCH2), 36.74 (C-6), 32.90 (ÃNHCH2CH2), 27.14
and 26.73 [2ꢁÈC(CH3)2], 20.81 [Ã
CH2CH3], 14.57 (ÃOCH2CH3), 14.36 [Ã
CH3]. Anal. C23H35NO6 (C, H, N).
H-6B and NHCH2), 1.57 (bs, 1H, NH), 1.41 and 1.28
[each s, each 3H, ÈC(CH3)2], 1.24 (m, 20H, alkyl
/
D
L
protons), 1.18 (t, Jꢃ
/
7.1 Hz, OCH2CH3), 0.80 (t, Jꢃ
/
6.67 Hz, alkyl CH3); 13C-NMR (CDCl3): d 172.05
(ÈCÄO), 111.76 [ÈC(CH3)2], 105.06 (C-1), 84.97 (C-
/
/
1
422 [Mꢂ
/
/
2), 82.58 (C-4), 81.53 (C-3), 60.55 (OCH2), 58.46
(OCH3), 54.56 (C-5), 47.58 (NHCH2), 36.71 (C-6),
32.2, 31.0, 30.01, 29.95, 29.71 and 27.68 (alkyl carbons),
26.70 and 26.14 [C(CH3)2], 14.50 and 14.37 (OCH2CH3
and CH2CH3). Anal. C25H47NO6 (C, H, N).
/
/
/
/
/
/
/
/
/
/
/
5.2.2.6. Ethyl-[3-O-benzyl-5,6-dideoxy-5-(dodec-1-yl)-
/
1,2-O-isopropylidene]-a-
heptofuranuronate (10). Colourless oil (91% yield); IR
(KBr, cmꢀ1): nmax 3332 (Ã
NH), 2921 and 2852 (CH3
and CH2 stretching), 1730 (ester); MS (FAB): m/z 535
D-gluco-
and
b-L-ido-
/
/
/
/
/
1
/
[Mꢂ
5.91 and 5.88 (d, Jꢃ
proton), 4.67 (d, Jꢃ11.8 Hz, 1H, Ã
Jꢃ3.7 Hz, 1H, H-2), 4.47 (d, Jꢃ
OCHBPh), 4.13 (d, Jꢃ2.8 Hz, 1H, H-4), 4.09 (q,
Jꢃ7.1 Hz, 2H, OCH2), 3.90 (d, Jꢃ2.8 Hz, 1H, H-3),
/
2]ꢂ; H-NMR (CDCl3): d 7.33 (m, 5H, ArÃ
3.7 Hz, 1H, H-1, distereomeric
OCHAPh), 4.62 (d,
11.8 Hz, 1H,
/
H),
Ã
/
/
/
Ã
/
/
/
/
/
/
/
/
/
Ã
/
/
/
/
/
/
3.26 (m, 1H, H-5), 2.60 and 2.41 (m, 4H, H-6 and
NHCH2), 1.69 (bs, 1H, NH), 1.47 and 1.31 [each s, each
3H, ÈC(CH3)2], 1.25 (m, 23H, methylene protons of
/
/
/
/
NH(CH2)2-
NH(CH2)3-
/
/
alkyl chain and Ã
CH2CH3); 13C-NMR (CDCl3): d 172.18 (ÈCÄ
137.58, 129.32, 128.36 and 128.31 (ArÃC), 112.07
[ÈC(CH3)2], 105.31 (C-1), 83.32 (C-2), 82.41 (C-4),
82.22 (C-3), 71.82 (ÃOCH2Ph), 60.64 (OCH2CH3),
/
OCH2CH3), 0.84 (t, Jꢃ
/
6.7 Hz, 3H,
/
O),
/
5.2.2.5. Ethyl-[3-O-methyl-5,6-dideoxy-5-(dodec-1-yl)-
1,2-O-isopropylidene]-a- -gluco and b- -ido-
D
L
/
heptofuranuronate (9). Minor isomer: Colourless oil
(15% yield); IR (KBr, cmꢀ1): nmax 3600 (NH), 2928,
2856, 2402, 2348 (CH3 and CH2 stretching), 1728
54.46 (C-5), 47.68 (NHCH2), 36.71 (C-6), 32.32, 30.85,
27.76 and 23.07 (alkyl carbons), 27.19 and 26.79
[C(ÈCH3)2], 14.57 and 14.43 (OCH2CH3 and
CH2CH3). Anal. C31H51NO6 (C, H, N).
(COOEt); MS (FAB): m/z 458 [Mꢂ
(CDCl3): d 5.86 (d, Jꢃ3.9 Hz, 1H, H-1), 4.56 (d, Jꢃ
3.9 Hz, 1H, H-2), 4.12 (q, Jꢃ7.1 Hz, 2H, OCH2CH3),
4.04 (d, Jꢃ2.7 Hz, 1H, H-4), 3.72 (d, Jꢃ2.7 Hz, 1H,
H-3), 3.41 (s, 3H, OCH3), 3.30 (m, 1H, H-5), 2.65 (m,
3H, H-6A and NHCH2), 2.44 (dd, Jꢃ13.6 and 5.5 Hz,
H-6B), 1.69 (bs, 1H, NH), 1.47 and 1.31 [each s, each
/
1]ꢂ; 1H-NMR
/
/
/
5.2.2.7. Ethyl-[3-O-methyl-5,6-dideoxy-5-(hexadec-1-
/
/
yl)-1,2-O-isopropylidene]-a-
heptofuranuronate (11). Minor isomer: Colourless oil
(35% yield); IR (KBr, cmꢀ1): nmax 3570 (Ã
NH), 2931,
2843, 2504 (CH3 and CH2 stretching), 1718 (ester); MS
D-gluco
and
b-L-ido-
/
/

R.P. Tripathi et al. / European Journal of Medicinal Chemistry 37 (2002) 773Á
/781
779
(FAB): m/z 514 [Mꢂ
Jꢃ3.8 Hz, 1H, H-1), 4.56 (d, Jꢃ
4.17Á4.04 (m, 3H, H-4 and OCH2), 3.79 (d, Jꢃ
1H, H-3), 3.41 (s, 3H, ÃOCH3), 3.31 (m, 1H, H-5), 2.65
(dd, Jꢃ18.3 and 4.5 Hz, 1H, H-6A), 2.46 (m, 3H, H-6B
/
1]ꢂ; 1H-NMR (CDCl3): d 5.86 (d,
3.8 Hz, 1H, H-2),
3.0 Hz,
yield); IR (KBr, cmꢀ1): nmax 3332, 2908, 2884, 1731; MS
(FAB): m/z 402 [Mꢂ
1]ꢂ; 1H-NMR (CDCl3): d 5.89 (d,
Jꢃ3.6 Hz, 1H, H-1), 4.57 (d, Jꢃ3.6 Hz, 1H, H-2), 4.16
(d, Jꢃ2.9 Hz, 1H, H-3), 4.13 (q, Jꢃ
OCH2CH3), 3.71 (dd, Jꢃ
3.42 (m, 1H, H-5), 3.40 (s, 3H, Ã
/
/
/
/
/
/
/
/
/
/
7.12 Hz, 2H,
/
Ã
/
/
4.1 and 3.4 Hz, 1H, H-4),
and NHCH2), 1.62 (bs, 1H, NH), 1.48 and 1.33 [each s,
/
OCH3), 2.50 (m, 1H,
each 3H, ÈC(CH3)2], 1.25 (m, 31H, methylene protons
NHCH), 2.39 (m, 2H, H-6), 1.58 (bs, 1H, NH), 1.36,
1.31 [each s, each 3H, ÈC(CH3)2], 1.30 (m, 9H, 3ꢁCH2
and OCH2CH3), 1.02 (d, Jꢃ6.5 Hz, 3H, CHCH3), 0.85
[d, Jꢃ6.5 Hz, 6H, CH(CH3)2]. Anal. C21H39NO6 (C, H,
N).
of alkyl chain and Ã
CH2CH3).
Major isomer: Colourless oil (65% yield); IR (KBr,
cmꢀ1): nmax 3650 (Ã
NH), 2913, 2843, 2504 (CH3 and
CH2 stretching), 1720 (ester); MS (FAB): m/z 514 [Mꢂ
1]ꢂ; 1H-NMR (CDCl3): d 5.93 (d, Jꢃ
3.8 Hz, 1H, H-1),
4.61 (d, Jꢃ3.8 Hz, 1H, H-2), 4.21 (d, Jꢃ3.07 Hz, 1H,
H-4), 4.15 (q, Jꢃ7.1 Hz, 2H, OCH2), 3.65 (d, Jꢃ3.07
Hz, 1H, H-3), 3.39 (s, 3H, OCH3), 3.31 (m, 1H, H-5),
2.66 (dd, Jꢃ19.7 and 4.2 Hz, 1H, H-6A), 2.47 (m, 3H,
/
OCH2CH3), 0.88 (t, Jꢃ/6.6 Hz, 3H,
/
/
/
/
/
/
5.2.2.10. Ethyl-[3-O-benzyl-1,5-(dimethyl
amino)-5,6-dideoxy-1,2-O-isopropylidene]-a-
and b-
yield); MS (FAB): m/z 478 [Mꢂ
hex-1-yl-
/
/
D-gluco-
/
/
L
-ido-heptofuranuronate (14). Colourless oil (90%
1]ꢂ; IR (KBr, cmꢀ1):
nmax 3334, 2949, 2869, 1733; H-NMR (CDCl3): d 7.33
(m, 5H, ArH), 5.91 (d, Jꢃ3.6 Hz, 1H, H-1), 4.68, 4.55
(two dd, each Jꢃ11.9 Hz, 2H, benzylic CH2), 4.60 (d,
Jꢃ3.6 Hz, 1H, H-2), 4.16 (d, Jꢃ2.9 Hz, 1H, H-3), 4.13
(q, Jꢃ7.12 Hz, 2H, ÃOCH2CH3), 3.71 (dd, Jꢃ4.1 Hz,
/
1
/
H-6B and NHCH2), 1.76 (bs, 1H, NH), 1.45 and 1.32
[each s, each 3H, ÈC(CH3)2], 1.28 (m, 31H, methylene
/
/
protons of alkyl chain and Ã
/
OCH2CH3), 0.87 (t, Jꢃ
/
6.6
/
/
Hz, 3H, CH2CH3); 13C-NMR (CDCl3): d 172.25 (ÈCÄ
/
/
/
/
O), 111.93 [ÈC(CH3)2], 105.14 (C-1), 84.47 (C-2), 82.69
(C-4), 81.59 (C-3), 60.75 (OCH2), 57.61 (OCH3), 54.56
(C-5), 47.58 (NHCH2), 36.71 (C-6), 32.2, 31.0, 30.01,
29.95, 29.71, 27.75, 27.68 and 23.07 (alkyl carbons),
26.70 and 26.14 [C(ÈCH3)2], 14.61 and 14.49
(OCH2CH3 and CH2CH3). Anal. C29H55NO6 (C, H,
N).
3.4 Hz, 1H, H-4), 3.42 (m, 1H, H-5), 3.40 (s, 3H, OCH3),
2.50 (m, 1H, NHCH), 2.39 (m, 2H, H-6), 1.58 (bs, 1H,
NH), 1.36 and 1.31 [each s, each 3H, C(CH3)2], 1.30 (m,
9H, 3ꢁ
CHCH3), 0.87 [d, Jꢃ
NMR (CDCl3): d 172.45 (CÄ
128.28 (ArÃC), 111.87 [C(CH3)2], 105.21 (C-1), 83.18
(C-2), 82.87 (C-4), 82.33 (C-3), 71.83 (OCH2Ph), 60.65
(ÃOCH2CH3), 51.74, 51.57, 51.04, 50.78 (diastereoiso-
/
CH2 and OCH2CH3), 1.03 (d, Jꢃ
6.5 Hz, 6H, CH(CH3)2]; 13C-
O), 137.5, 128.8, 128.4,
/
6.5 Hz, 3H,
/
/
/
5.2.2.8. Ethyl-[3-O-benzyl-5,6-dideoxy-5-(hexadec-1-
/
yl)-1,2-O-isopropylidene]-a-
heptofuranuronate (12). Colourless solid (92% yield);
IR (KBr, cmꢀ1): nmax 3332 (Ã
NH), 2921 and 2852 (CH3
and CH2 stretching), 1730 (ester); MS (FAB): m/z 591
D-gluco
and
b-
L-ido-
meric NHCHCH3 and C-5), 39.53, 38.81, 37.88, 37.49
(CH2’s), 27.13 and 26.71 [C(CH3)2], 24.40, 23.90 (CH2),
22.92, 21.7 (CH3), 20.70 [CH(CH3)2], 14.57 (CH3).
Anal. C27H43NO6 (C, H, N).
/
1
[Mꢂ
5.94 and 5.91 (d, Jꢃ
proton), 4.68 (d, Jꢃ11.8 Hz, 1H, Ã
Jꢃ3.7 Hz, 1H, H-2), 4.47 (d, Jꢃ
OCHBPh), 4.14 (d, Jꢃ2.7 Hz, 1H, H-4), 4.08 (q,
Jꢃ7.1 Hz, 2H, OCH2), 3.92 (d, Jꢃ2.7 Hz, 1H, H-3),
/
2]ꢂ; H-NMR (CDCl3): d 7.32 (m, 5H, ArÃ
3.7 Hz, 1H, H-1, distereomeric
OCHAPh), 4.64 (d,
11.8 Hz, 1H,
/H),
/
5.2.2.11. Ethyl-[5-(carbethoxy
dideoxy-1,2-O-isopropylidene-3-O-methyl]-a-D
ethyl
amino)-5,6-
-gluco
/
/
/
/
and b-L-ido-heptofuranuronate (15). Minor isomer:
Colourless oil (20% yield), IR (KBr, cmꢀ1): nmax 3648,
2982, 1730; MS (FAB): m/z 389 [M]ꢂ; 1H-NMR
Ã
/
/
/
/
3.43 (m, 1H, H-5), 2.61 and 2.34 (m, 4H, H-6 and
NHCH2), 1.68 (bs, 1H, NH), 1.47 and 1.31 [each s, each
3H, ÈC(CH3)2], 1.24 (m, 31H, methylene protons of
(CDCl3): d 5.85 (d, Jꢃ
Jꢃ3.8 Hz, 1H, H-2), 4.20 (m, 5H, H-4, 2ꢁ
3.70 (d, Jꢃ2.85 Hz, 1H, H-3), 3.42 (s, 3H, Ã
/
3.69 Hz, 1H, H-1), 4.57 (d,
OCH2CH3),
OCH3),
/
/
/
/
alkyl chain and Ã
CH2CH3); 13C-NMR (CDCl3): d 172.22 (ÈCÄ
137.53, 128.87, 128.42 and 128.26 (ArÃC), 111.97
[ÈC(CH3)2], 105.22 (C-1), 82.52 (C-2), 82.22 (C-4),
82.11 (C-3), 71.89 (ÃOCH2Ph), 60.69 (OCH2CH3),
/
OCH2CH3), 0.87 (t, Jꢃ/6.6 Hz, 3H,
3.38 (m, 1H, H-5), 2.95 and 2.50 (each m, each 3H, H-6
and NHCH2), 1.75 (bs, 1H, NH), 1.47 and 1.31 [each s,
/O),
/
each 3H, ÈC(CH3)2], 1.25 (t, Jꢃ
OCH2CH3’s); 13C-NMR (CDCl3): d 173 (CÄ
112.0 [ÈC(CH3)2], 105.2 (C-1), 84.03 (C-2), 82.23 (C-
4), 81.79 (C-3), 60.67 (ÃOCH2CH3), 57.92 (ÃOCH3),
52.78 (C-5), 42.9, 36.88, 35.81 (ÃCH2’s), 27.14, 26.6 and
14.6 (CH3’s).
/
7.13 Hz, 6H,
Ã
/
/
O),
/
54.46 (C-5), 47.75 (NHCH2), 36.79 (C-6), 32.32, 30.83,
30.09, 27.75, and 23.08 (alkyl carbons), 27.15 and 26.72
[C(ÈCH3)2], 14.58 and 14.49 (OCH2CH3 and
CH2CH3). Anal. C35H59NO6 (C, H, N).
/
/
/
Major isomer: Colourless oil (70% yield); IR (KBr,
cmꢀ1): nmax 3340, 2930, 1738; MS (FAB): m/z 389
5.2.2.9. Ethyl-[1,5-(dimethyl
dideoxy-1,2-O-isopropylidene-3-O-methyl]-a-
and b- -ido-heptofuranuronate (13). Colourless oil (90%
hex-1-yl-amino)-5,6-
[M]ꢂ; 1H-NMR (CDCl3): d 5.89 (d, Jꢃ
/
3.8 Hz, 1H, H-
3.69 Hz, 1H, H-2), 4.20 (m, 5H, H-4, 2ꢁ
OCH2CH3), 3.70 (d, Jꢃ2.96 Hz, 1H, H-3), 3.37 (s, 3H,
D-gluco-
1), 4.55 (d, Jꢃ
/
/
L
/

780
R.P. Tripathi et al. / European Journal of Medicinal Chemistry 37 (2002) 773Á781
/
Ã
/
OCH3), 3.34 (m, 1H, H-5), 2.96 (t, Jꢃ
/
6.6 Hz, 2H,
13C-NMR (CDCl3): d 175.0, 174.19 (2ꢁ
COOEt),
/
NHCH2), 2.49 (m, each 4H, H-6 and COCH2), 1.99 (bs,
1H, NH), 1.48 and 1.31 [each s, each 3H, C(CH3)2], 1.23
139.36, 130.24, 129.65, 129.51 (ArC), 113.3 (qC), 106.5
(C-1), 83.92, 83.48, 82.10 (C-2, C-4, C-3), 72.39 (benzylic
CH2), 61.52 (OCH2), 54.34 (C-5), 47.86 (NHCH2), 37.57
(C-6), 32.44 (COCH2), 26.22 (NHCH2CH2CH2), 27.17,
26.72 and 14.59 (CH3’s).
(t, Jꢃ
d 172.15 (CÄ
(C-2), 82.58 (C-4), 81.49 (C-3), 60.86 and 60.73
OCH3), 54.27 (C-5), 43.00,
/
7.13 Hz, 6H, Ã
/
OCH2CH3’s); 13C-NMR (CDCl3):
/
O), 112.0 [C(CH3)2], 105.16 (C-1), 84.49
(Ã
/
OCH2CH3), 57.66 (Ã
/
Major isomer: Colourless oil (70% yield); IR (KBr,
36.78 and 35.52 (CH2’s), 27.12, 26.67 and 14.60
(CH3’s). Anal. C18H31NO8 (C, H, N).
cmꢀ1): nmax 3400, 2928, 1730; MS (FAB): m/z 480 [Mꢂ
/
1
1]ꢂ; H-NMR (CDCl3): d 7.33 (m, 5H, ArH), 5.87 (d,
Jꢃ3.7 Hz, 1H, H-1), 4.57 (d, Jꢃ3.7 Hz, 1H, H-2), 4.60
and 4.53 (two d, Jꢃ13.3 Hz, each 1H, benzylic CH2),
4.07 (m, 6H, H-4, H-3, 2ꢁ OCH2), 3.40 (m, 1H, H-5),
2.66 (m, 4H, NHCH2, H-6), 2.28 (t, Jꢃ7.1 Hz, 2H,
COCH2), 1.79 (bs, 1H, NH), 1.66 (t, Jꢃ7.1 Hz, 2H,
NHCH2CH2CH2), 1.30, 1.28 [each s, each 3H,
C(CH3)2], 1.25 and 1.22 (each t, each Jꢃ7.1 Hz, each
3H, 2ꢁ
OCH2 CH3); 13C-NMR (CDCl3): d 172.2,
170.5 (2ꢁCOOEt), 137.5, 128.88, 128.45, 128.30 (ArC),
111.5 [C(CH3)2], 105.20 (C-1), 82.55, 82.21, 82.08 (C-2,
C-4, C-3), 71.90 (benzylic CH2), 60.71, 60.52 (2ꢁ
/
/
5.2.2.12. Ethyl-[3-O-benzyl-5-(carbethoxy
amino)-5,6-dideoxy-1,2-O-isopropylidene]-a-
ethyl
-gluco-
/
D
/
Ã
/
and b-
L
-ido-heptofuranuronate (16). Colourless oil (90%
/
yield); IR (KBr, cmꢀ1): nmax 3444, 2982, 1732; MS
/
(FAB): m/z 465 [M]ꢂ; H-NMR (CDCl3): d 7.42 (m,
1
5H, ArH), 5.92 (d, Jꢃ
3.74 Hz, 1H, H-2), 4.62 and 4.15 (two d, Jꢃ
1H, benzylic CH2), 4.07 (m, 5H, H-4, 2ꢁ OCH2), 3.91
(d, Jꢃ3.06 Hz, 1H, H-3), 3.35 (m, 1H, H-5), 2.93 (t,
Jꢃ6.78 Hz, 2H, NHCH2), 2.44 (t, Jꢃ6.7 Hz, 1H,
COCH2), 2.32 and 2.28 (each d, Jꢃ4.6 and 6.7 Hz, each
1H, H-6), 1.27 and 1.31 [each s, each 3H, C(CH3)2], 1.23
(t, Jꢃ
7.0 Hz, 6H, OCH2CH3); 13C-NMR (CDCl3): d
172.92, 172.04 (2ꢁCOOEt), 137.42 (ArC), 128.85,
/
3.74 Hz, 1H, H-1), 4.66 (d, Jꢃ
/
/
/12 Hz, each
/
Ã
/
/
Ã
/
/
/
/
/
/
Ã
/
/
OCH2), 54.19 (C-5), 46.73 (NHCH2), 36.76 (C-6),
32.52 (COCH2), 26.08 (NHCH2CH2CH3), 27.12, 26.68
and 14.58 (CH3’s). Anal. C25H37NO8 (C, H, N).
/
/
128.42, 128.28 (ArC), 111.95 [C(CH3)2], 105.20 (C-1),
82.54 and 82.13 (C-2, C-4), 71.86 (C-3), 60.76 and 60.14
5.2.3. General procedure for the preparation of
compounds 19Á22
/
(2ꢁ OCH2), 54.02 (ArCH2), 43.01, 36.65 and 35.53
/
Ã
/
(CH2’s), 27.09, 26.66 and 14.53 (CH3’s). Anal.
C24H35NO8 (C, H, N).
5.2.3.1. 5-Amino-5,6-dideoxy-1,2-O-isopropylidene-3-O-
methyl-a- -gluco- and b- -ido-heptofuranuronic acid
D
L
(19). To the magnetically stirred solution of the ethyl-
[5-amino-5,6-dideoxy-3-O-methyl-1,2-O-isopropyli-
5.2.2.13. Ethyl-[3-O-methyl-5-(carbethoxypropyl
amino)-5,6-dideoxy-1,2-O-isopropylidene]-a-
D
-gluco-
-ido-heptofuranuronate (17). Colourless oil (90%
dene]-a-
D-gluco- and b-
L-ido-heptofuranurnate (2.82 g,
and b-
L
9.757 mmol) in aq. EtOH (50%, 57 mL), Et3N (14.5 mL)
was added and the contents were stirred for 50 h.
Solvent evaporated under reduced pressure with an
azeotrop of EtOH and C6H5CH3 to give a residual
mass which was subjected to column chromatography
yield); IR (KBr, cmꢀ1): nmax 2980, 2930, 2880, 1730
1
(ester); MS (FAB): 405 [Mꢂ
5.89 (d, Jꢃ
H-2), 4.13 (m, 5H, H-4, 2ꢁ
Hz, 1H, H-3), 3.37 (s, 3H, OCH3), 3.36 (m, 1H, H-5),
2.78 (t, Jꢃ6.7 Hz, 2H, NHCH2), 2.31 (m, 4H, H-6 and
COCH2), 1.78 (m, 2H, NHCH2CH2CH2), 1.32 and 1.28
[each s, each 3H, C(CH3)2], 1.24 (t, Jꢃ7.1 Hz, 6H, 2ꢁ
OCH2 CH3). Anal. C19H33NO8 (C, H, N).
/
2]ꢂ; H-NMR (CDCl3): d
/
4.02 Hz, 1H, H-1), 4.58 (d, Jꢃ/4.02 Hz, 1H,
/
Ã
/
OCH2), 3.70 (d, Jꢃ
/
2.84
over SiO2 using CHCl3ÁMeOH (9:1) as eluant to 19 as
/
/
colourless solid, m.p. 200 8C (91% yield); IR (KBr,
cmꢀ1): nmax 2900, 2800 (CH3CH2 stretching); MS
1
/
/
(FAB): m/z 262 [Mꢂ
(d, Jꢃ
4.33 (d, Jꢃ
3.98 (m, 1H, H-5), 3.40 (Ã
1.43 and 1.33 [each s, each 3H, ÈC(CH3)]; 13C-NMR
(CDCl3): d 168.5 (ÈCÄO), 111.5 [ÈC(CH3)2], 105.19
/
1]ꢂ; H-NMR (CDCl3): d 5.89
Ã
/
/
3.2 Hz, 1H, H-1), 4.52 (d, Jꢃ
6.3 Hz, H-4), 4.08 (d, Jꢃ
OÃCH3), 2.50 (m, 2H, H-6),
/
3.2 Hz, 1H, H-2),
3.2 Hz, 1H, H-3),
/
/
5.2.2.14. Ethyl-[3-O-benzyl-5-(carbethoxypropyl
amino)-5,6-dideoxy-1,2-O-isopropylidene]-a- -gluco and
/
/
D
b-
L
-ido-heptofuranuronate (18). Minor isomer: Colour-
/
less oil (20% yield); IR (KBr, cmꢀ1): nmax 3681, 3022,
(C-1), 83.77 (C-2), 82.57 (C-4), 81.93 (C-3), 58.21 (Ã
/
1
2987, 2837, 1728; MS (FAB): m/z 480 [Mꢂ
/
1]ꢂ; H-
OCH3), 47.81 (C-5), 38.62 (C-6), 27.13 and 26.69
[ÈC(CH3)2]. Anal. C11H19NO6 (C, H, N).
NMR (CDCl3): d 7.33 (m, 5H, ArH), 5.87 (d, Jꢃ
Hz, 1H, H-1), 4.58 (d, Jꢃ3.7 Hz, 1H, H-2), 4.66 and
4.54 (two d, Jꢃ12 Hz, each 1H, benzylic CH2), 4.10 (m,
6H, H-4, H-3, 2ꢁ OCH2), 3.35 (m, 1H, H-5), 2.52 (m,
4H, H-6, NHCH2), 2.28 (t, Jꢃ7.1 Hz, 2H, COCH2),
1.66 (t, Jꢃ7.1 Hz, 2H, NHCH2CH2CH2), 1.52 (bs, 1H,
NH), 1.47 and 1.31 [each s, each 3H, ÈC(CH3)2], 1.25,
1.22 (each t, each Jꢃ7.1 Hz, each 3H, 2ꢁOCH2CH3);
/
3.7
/
/
5.2.3.2. 5-Amino-5,6-dideoxy-1,2-O-isopropylidene-3-O-
/
Ã
/
benzyl-a-D-gluco- and b-L-ido-heptofuranuronic acid
(20). Colourless solid, m.p. 164 8C (90% yield); IR
/
/
(KBr, cmꢀ1): nmax 2980, 2930, 2880, 1730; MS (FAB):
1
m/z 338 [Mꢂ
/
1]ꢂ; H-NMR (CDCl3): d 7.35 (m, 5H,
/
/
ArH), 5.89 (d, Jꢃ
/
3.18 Hz, 1H, H-1), 4.56 (d, Jꢃ3.18
/

R.P. Tripathi et al. / European Journal of Medicinal Chemistry 37 (2002) 773Á
/781
781
Hz, 1H, H-2), 4.52 (m, 3H, benzylic CH2 and H-4), 4.08
and ICMR, New Delhi for financial Assistance. Authors
are also thankful to Dr A.P.B. for his valuable
comments during the study.
(d, Jꢃ2 Hz, 1H, H-3), 3.69 (m, 1H, H-5), 2.39 (bs, 2H,
/
NH2), 1.43 and 1.33 [each s, each 3H, ÈC(CH3)2]; 13C-
NMR (CDCl3): d 171.36 (COOH), 135.84, 126.73,
126.20, (ArC), 109.58 [C(CH3)2], 102.86 (C-1), 79.51,
78.55, 77.60 (C-2, C-4 and C-3), 69.24 (Ã
/OCH2Ph),
34.68 (C-6), 46.98, 46.38 (diastereoisomeric C-5), 26.91
and 26.47 [ÈC(CH3)2]. Anal. C17H23NO6 (C, H, N).
References
[1] P. Sudre, G. ten Dam, A. Kochi, Bull.World Health Organ. 70
(1992) 149.
5.2.3.3. 5,6-Dideoxy-5-(dodecyl
isopropylidene-3-O-methyl-a- -gluco-
heptofuran-6-oic acids (21). Colourless foam (84%
yield); IR (KBr, cmꢀ1): nmax 3986.6 (Ã
OH), 2856,
2270 (CH3 and CH2 stretching), 1585 (ÈCÄO); MS
1]ꢂ; H-NMR (CDCl3): d 5.84
3.7 Hz, 1H, H-1), 4.55 (d, Jꢃ3.5 Hz,
1H, H-2), 4.22 (d, Jꢃ2.4 Hz, 1H, H-4), 3.68 (d, Jꢃ2.4
OCH3), 3.16 (m, 1H, H-5),
amino)-1,2-O-
D
and b- -ido-
L
[2] R.E. Huebner, K.G. Castro, Ann. Rev. Med. 46 (1995) 47.
[3] V. St. Georgiev, Int. J. Antimicrob. Agents 4 (1994) 157.
[4] R.F. Jacobs, Clin. Infect. Dis. 19 (1994) 1.
/
[5] J. Trias, R. Benz, Mol. Microbiol. 19 (1994) 283.
[6] N.K. Rastogi, S. Goh, H.L. David, Antimicrob. Agents Che-
mother. 34 (1990) 750.
/
1
(FAB): m/z 430 [Mꢂ
/
and 5.79 (d, Jꢃ
/
/
[7] P.J. Brennan, H. Nikaido, Ann. Rev. Biochem. 64 (1995) 63.
[8] M. Julius, C.A. Free, G.T. Barry, Methods Enzymol. Sect. A 17
(1970) 171.
/
/
Hz, 1H, H-3), 3.37 (s, 3H, Ã
/
[9] N.E. Caceres, N.B. Harris, J.F. Wellehan, Z. Feng, V. Kapur,
R.G. Baletta, J. Bacteriol. 179 (1997) 5046.
2.63 and 2.23 (each m, each 2H, H-6 and NHCH2), 1.87
(bs, 1H, NH), 1.47 and 1.29 [each s, each 3H,
[10] (a) P.R.J. Gangadharam, M.D. Iseman (Eds.), Antimicrob.
Agents Annals, vol. 2, Elsevier Science Publishers BV, Amster-
dam, 1987, p. 14;
ÈC(CH3)2], 1.24 (m, 20H, alkyl protons), 0.85 (t, Jꢃ
/
7.1 Hz, alkyl CH3); 13C-NMR (CDCl3): d 182.48 (ÈCÄ
/
(b) R. Wise, J.M. Address, Antimicrob. Agents Chemother. 25
(1984) 612.
O), 116.48 [ÈC(CH3)2], 109.78 (C-1), 88.79 (C-2), 86.31
(C-4), 83.96 (C-3), 62.46 (C-5), 59.28 (OCH3), 51.74
(NHCH2), 36.70 (C-6), 36.02, 35.50, 35.13, 33.31, 33.20
and 28.46 (alkyl carbons), 32.70 and 32.26 [ÈC(CH3)2],
[11] F.C. Neuhas, D. Gotlich, P.L. Shaw (Eds.), Antibiotics, vol. 1,
Springer-Verlag, Heidelberg, Germany, 1967, p. 40.
[12] F.C. Hammes, W.P. Hammes, Pharmacol. Ther. 14 (1981) 265.
[13] J.A. Maddry, N. Bansal, L.E. Bermudez, R.N. Comber, I.M.
Orme, W.J. Suling, L.N. Wilson, R.C. Raynolds, Biorg. Med.
Chem. Lett. 8 (1998) 237.
20.02 (Ã/CH2CH3). Anal. C23H43NO6 (C, H, N).
5.2.3.4. 5,6-Dideoxy-5-(hexadecyl
isopropylidene-3-O-methyl-a- -gluco-
heptofuran-6-oic acids (22). Colourless foam (75%
yield); IR (KBr, cmꢀ1): nmax 3876.5 (Ã
OH), 2873,
2673 (CH3 and CH2 stretching), 1585 (ÈCÄO); MS
1]ꢂ; H-NMR (CDCl3): d 5.92
3.8 Hz, 1H, H-1), 4.53 (d, Jꢃ3.8 Hz,
1H, H-2), 4.21 (d, Jꢃ2.6 Hz, 1H, H-4), 3.71 (d, Jꢃ2.6
Hz, 1H, H-3), 3.39 (s, 3H, ÃOCH3), 3.20 (m, 1H, H-5),
amino)-1,2-O-
[14] T.B. John, D. Varalakshmi, S. Todd, K. Takayama, J.B. Patrick,
G.S. Besra, Science 276 (1997) 1420.
D
and b- -ido-
L
[15] (a) G.A. Chung, Z. Aktar, S. Jackson, K. Duncan, Antimicrob.
Agents Chemother. 39 (1995) 2235;
/
(b) J.M. Dickinson, D.A. Mitchison, Tubercle 66 (1985) 109.
[16] Identification of inhibitors of DNA Topoisomerase-II from a
synthetic library of glycoconjugates, R.P. Tripathi, S.K. Rastogi,
B. Kundu, J.K. Saxena, V.J.M. Reddy, S. Srivastava, S. Chandra,
A.P. Bhaduri, Comb. Chem. High Throughput Screen. 4 (2001)
/
1
(FAB): m/z 488 [Mꢂ
/
and 5.89 (d, Jꢃ
/
/
/
/
237Á244.
/
/
[17] A. Namane, C. Goujette, M.P. Fillion, G. Fillion, T. Huynh
2.60 and 2.36 (each m, each 2H, H-6 and NHCH2), 1.85
(bs, 1H, NH), 1.52 and 1.31 [each s, each 3H,
Dinh, J. Med. Chem. 35 (1992) 3039.
[18] J.F. Fischer, A.W. Harrison, G.L. Bundy, K.F. Wilkinson, B.D.
Rush, M.J. Ruwart, J. Med. Chem. 34 (1991) 4140.
[19] E. Negre, M.L. Chance, S.Y. Hanbuta, M. Monsigny, A.C.
Roche, R.M. Mayer, Antimicrob. Agents Chemother. 35 (1992)
2228.
ÈC(CH3)2], 1.24 (m, 28H, alkyl protons), 0.85 (t, Jꢃ
/
7.0 Hz, alkyl CH3); 13C-NMR (CDCl3): d 178.78 (ÈCÄ
/
O), 112.04 [ÈC(CH3)2], 105.01 (C-1), 84.47 (C-2), 82.09
(C-4), 81.07 (C-3), 57.89 (OCH3), 54.45 (C-5), 32.29 (C-
6), 36.97, 30.12, 29.74, 27.79 and 23.05 (CH2’s), 27.12
[20] M.L. Wolform, S. Hanessian, J. Org. Chem. 27 (1962) 1800.
[21] K. Freudenberg, W. Dun, H. von Hochstetter, Ber. Dtsch. Chem.
Ges. 61 (1928) 1732.
and 26.763 [ÈC(CH3)2], 14.46 (Ã
/CH2CH3). Anal.
C27H51NO6 (C, H, N).
[22] K.N. Houk, N.M. Paddon Row, N.G. Rondon, Y.D. Wu, F.K.
Brown, C.D. Spellmeyer, J.T. Metz, Y.L. Li, R.J. Loncharich,
Science 231 (1986) 1108.
[23] L.A. Collins, S.G. Franzblan, Antimicrob. Agents Chemother. 41
(1997) 1004.
Acknowledgements
[24] H. Saita, H. Tomioka, K. Sato, T. Yamne, K. Yamashita, K.
Hosol, Antimicrob. Agents Chemother. 35 (1991) 542.
[25] C.N. Lee, L.B. Heifets, Am. Rev. Respir. Dis. 136 (1967) 349.
Authors gratefully acknowledge the financial assis-
tance from Department of Ocean Development, India